diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5ee3479..21d9cf3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ Bug fixes from a review of 0.1.3, and live progress on a terminal. No new comman
 - **usage summary** shows the enforced monthly allowance. **status** fails when the key check cannot reach the API.
 - **mcp install / init** back up the client config to `.bak`, write through symlinks, refuse to replace a customised `spicrawl` entry without `--force`, and accept VS Code JSONC/BOM `mcp.json`.
 - **Docs:** the embedded skill, `openapi.yaml` and schemas are synced with the API (cache hits are billed, `impersonate` defaults to true, batch honours `--format`).
+- **No engine or browser names.** Customers see three rendering tiers, `fetch`, `js` and `browser`, never an engine. `sessions create --engine` and `browser url --engine` take a tier; the old engine names still work (sent as typed) with a deprecation notice on stderr that does not repeat them. On `scrape` and `batch submit`, `--engine` and the display flag next to it, which the API already ignores, are hidden from `--help` but still accepted. Human output (tables, `--meta`, warnings, errors, `logs get`) shows a tier for any engine name the API sends; `--json` and `--jsonl` stay exactly as the API sent them. The help, `openapi.yaml`, the schemas, the embedded skill and the README use tier names.
 - **install.sh** accepts `SPICRAWL_VERSION=0.1.3` as well as `v0.1.3` and explains a failed download. The npm launcher forwards Ctrl-C to the binary.
 
 ## 0.1.3 — 2026-10-05
diff --git a/DESIGN.md b/DESIGN.md
index d8cd746..a766d89 100644
--- a/DESIGN.md
+++ b/DESIGN.md
@@ -60,6 +60,17 @@ never invent a field the API does not accept (the API rejects unknown fields).
    the key) once on stdout; its connection hints on stderr use
    `$SPICRAWL_BROWSER_URL` and are suppressed by `-q`. A `ws://` URL warns on
    stderr, always, that the key travels unencrypted.
+10. **Engine routing is internal.** A customer sees three rendering tiers,
+    `fetch`, `js` and `browser`, and never an engine or browser name. The API
+    already reports tiers. `sessions create` and `browser url` take a tier with
+    `--engine`; the engine names older CLIs took (which the API still honours)
+    are sent as typed, with a deprecation notice on stderr that does not repeat
+    them. `scrape` and `batch submit` keep `--engine` and the display flag next
+    to it hidden: the API ignores both and says so (`ENGINE_IGNORED`). In human output any
+    engine name the API sends is shown as its tier (`output.Tier`,
+    `output.PublicText`). JSON and `--jsonl` are the API's data and stay exactly
+    as sent. `internal/cmd/engine_names_test.go` locks the help, the human
+    output and the embedded skill and specs.
 
 ## Configuration
 
@@ -111,11 +122,11 @@ spicrawl scrape <url|-> [flags]                   POST /v1/scrape
   --format html|markdown|text|json|pdf          response_format
   --render                                      js_render
   --stealth  --impersonate
-  --engine fetch|obscura|chromium|camoufox  --mode auto
+  --mode auto
   --premium-proxy  --country CC  --proxy URL  --proxy-verify  --sticky-key K
   --session ID
   --wait MS  --wait-for SEL  --wait-for-timeout MS
-  --block images,fonts,...  --headless=false
+  --block images,fonts,...
   --header 'Name: value' (repeatable)            custom_headers
   --extract JSON|@file  --ai PROMPT  --ai-schema JSON|@file  --autoparse  --links
   --main-content/--no-main-content  --include SEL  --exclude SEL  --no-parse-pdf
@@ -141,10 +152,10 @@ spicrawl batch cancel <id> [--yes]                           --yes required with
 spicrawl batch retry|close <id>
 spicrawl batch append <id> <file|->
 
-spicrawl sessions create [--engine E] [--ttl S] [--country CC] [--rotate-ip] [--sticky-key K]
+spicrawl sessions create [--engine fetch|js|browser] [--ttl S] [--country CC] [--rotate-ip] [--sticky-key K]
 spicrawl sessions list | get <id> | context <id> | release <id> | delete <id> [--yes]
 
-spicrawl browser url [--engine chromium|obscura] [--country CC] [--ttl S] [--headless=false]
+spicrawl browser url [--engine browser|js] [--country CC] [--ttl S]
                                                 prints the wss:// CDP URL once (stdout)
 
 spicrawl logs [--errors] [--status S] [--limit N] [--all] [--all-projects]
diff --git a/README.md b/README.md
index fb2aac5..99883f8 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@ The result is one JSON object with the page under `content`:
 `spicrawl` is a single native binary that calls the [Spicrawl](https://spicrawl.com) web scraping API:
 
 - **Five output formats.** `--format` takes `html` (the API default), `markdown`, `text`, `json` or `pdf`; Markdown keeps only the main content unless you pass `--no-main-content`.
-- **JavaScript rendering.** `--render` runs the page in a browser, `--wait-for` waits for a CSS selector, and `--engine` pins `fetch`, `obscura` or `chromium` (`camoufox` is coming soon).
+- **JavaScript rendering.** `--render` runs the page's JavaScript and `--wait-for` waits for a CSS selector. The API picks the rendering tier (`fetch`, `js` or `browser`) from what the request needs; there is no engine to choose.
 - **Batch jobs of up to 10,000 URLs.** `spicrawl batch submit` sends up to 10,000 URLs and 1 MiB per request as one server-side job, runs up to 50 items at once (server default 10) and tries each item up to 10 times (default 3).
 - **Parallel scrapes from stdin.** `spicrawl scrape -` reads one URL per line and runs 4 requests at once by default (`--concurrency`), with every scrape flag available.
 - **Structured data without a model.** `--extract` (CSS selectors), `--autoparse` (JSON-LD, OpenGraph) and `--links`.
@@ -146,8 +146,8 @@ For other clients (Gemini CLI, OpenCode, Factory Droid, Devin and more) use the
 |---|---|
 | `spicrawl scrape <url\|->` | Fetch one page, or many from stdin, as Markdown, HTML, text, JSON, PDF or extracted data |
 | `spicrawl batch` | Run up to 10,000 URLs as one server-side job: `submit`, `wait`, `get`, `list`, `results`, `content`, `retry`, `cancel`, `append`, `close` |
-| `spicrawl sessions` | Keep one engine and cookie jar across scrapes: `create`, `list`, `get`, `context`, `release`, `delete` |
-| `spicrawl browser` | Cloud browser over the Chrome DevTools Protocol (`browser url`). Coming soon |
+| `spicrawl sessions` | Keep one rendering tier and cookie jar across scrapes: `create`, `list`, `get`, `context`, `release`, `delete` |
+| `spicrawl browser` | Cloud browser over a DevTools Protocol (CDP) WebSocket (`browser url`). Coming soon |
 | `spicrawl init` | Set up AI agent clients: MCP server config and the agent skill |
 | `spicrawl mcp` | `mcp install`: add the hosted MCP server to a client's config |
 | `spicrawl skill` | `skill install`: write the agent skill (`SKILL.md`) where each client looks for it |
@@ -215,11 +215,11 @@ AI extraction with a plain-language prompt or a JSON Schema (`--ai`, `--ai-schem
 
 ### How to take a screenshot or save a page as PDF
 
-Screenshots and PDF output need the Chromium engine:
+Screenshots and PDF output are rendered in a full browser, which the API picks for you:
 
 ```sh
-spicrawl scrape https://example.com --engine chromium --screenshot --screenshot-full-page -o home.html
-spicrawl scrape https://example.com/report --engine chromium --format pdf -o report.pdf
+spicrawl scrape https://example.com --screenshot --screenshot-full-page -o home.html
+spicrawl scrape https://example.com/report --format pdf -o report.pdf
 ```
 
 Screenshots are saved next to the `-o` file as `<name>.<label>.<format>`, or into `--screenshot-dir`; `--screenshot-selector` and `--screenshot-format png|jpeg|webp` narrow them. PDF is never written to a terminal: pass `-o FILE`, or `--json` to get it base64-encoded.
@@ -239,10 +239,10 @@ Each batch item is one fetch or render, returned as `html` (the default), `markd
 
 ### How to keep cookies and logins across scrapes
 
-A session keeps one engine and one cookie jar across many scrapes, so a login or a cart survives between requests:
+A session keeps one rendering tier and one cookie jar across many scrapes, so a login or a cart survives between requests:
 
 ```sh
-SID=$(spicrawl sessions create --engine chromium --ttl 7200 --json | jq -r .id)
+SID=$(spicrawl sessions create --engine browser --ttl 7200 --json | jq -r .id)
 spicrawl scrape https://example.com/account --session "$SID" --format markdown
 spicrawl sessions release "$SID"
 ```
@@ -340,11 +340,11 @@ Up to 10,000 URLs, and 1 MiB of request body, per `spicrawl batch submit`. A job
 
 ### Does it render JavaScript?
 
-Yes: add `--render` to run the page in a browser, and `--wait-for '<css selector>'` to wait for the content. `--engine chromium` pins real Chromium, which screenshots and PDF need.
+Yes: add `--render` to run the page in a browser, and `--wait-for '<css selector>'` to wait for the content. Screenshots and PDF are rendered in a full browser automatically; you do not pick one.
 
 ### Is Spicrawl free?
 
-Spicrawl is priced in credits: each successful request draws on your organization's monthly credit allowance. The [credits page](https://docs.spicrawl.com/credits) lists 1 credit for a plain fetch, 3 with `--render` and 8 with `--engine chromium`; failed requests cost 0, and a cache hit is billed at the price of the fetch that stored it. `spicrawl usage summary` shows the current period against your allowance.
+Spicrawl is priced in credits: each successful request draws on your organization's monthly credit allowance. The [credits page](https://docs.spicrawl.com/credits) lists 1 credit for a plain fetch, 3 with `--render` and 8 for a screenshot or PDF (full-browser rendering); failed requests cost 0, and a cache hit is billed at the price of the fetch that stored it. `spicrawl usage summary` shows the current period against your allowance.
 
 ### Does it work with Claude Code, Cursor, Codex and VS Code?
 
diff --git a/internal/cmd/assets/skill.md b/internal/cmd/assets/skill.md
index e2d66c8..d91438a 100644
--- a/internal/cmd/assets/skill.md
+++ b/internal/cmd/assets/skill.md
@@ -6,7 +6,7 @@ description: Fetch, render and extract data from web pages with Spicrawl, throug
 # Spicrawl
 
 Spicrawl turns any URL into clean content or structured data. One request, one URL,
-one response; the platform picks the engine, the proxy exit and the retries.
+one response; the platform picks the rendering path, the proxy exit and the retries.
 
 | | |
 |---|---|
@@ -46,19 +46,26 @@ needs `read`. A missing scope returns `403 ERR::AUTH::INSUFFICIENT_SCOPE`, namin
 ## MCP tools
 
 Connect a client to `https://mcp.spicrawl.com/mcp` with the header
-`Authorization: Bearer $SPICRAWL_API_KEY` (or run `spicrawl mcp install`, below).
+`Authorization: Bearer $SPICRAWL_API_KEY` (or run `spicrawl mcp install`, below). `x-api-key`,
+`api-key` or the raw key as the `Authorization` value are also accepted; a key in the URL is never read.
+`initialize` and `tools/list` work without a key, so a client can list the tools first; every tool
+call needs one (`401` otherwise).
+
+Every tool returns `structuredContent` (a JSON object matching its output schema) as well as the
+text: read its fields directly instead of parsing the text. A string or array payload comes wrapped
+as `{"content": …}`.
 
 | Tool | Use it to |
 |---|---|
-| `spicrawl_scrape` | Fetch one URL. Arguments: `url`, `format` (`markdown` default, `text`, `html`, `json`), `render` (JavaScript), `proxy`, `mode`, `engine`, `wait_for`, `wait`, `main_content_only`, `include_tags`, `exclude_tags`, `links`, `autoparse`, `extract`, `ai_extract` (coming soon), `screenshot`, `actions`, `session_id`, `cache`, `max_cost` and the other `/v1/scrape` fields. Note `render`/`format` instead of the API's `js_render`/`response_format`. |
+| `spicrawl_scrape` | Fetch one URL. Arguments: `url`, `format` (`markdown` default, `text`, `html`, `json`), `render` (JavaScript), `proxy`, `mode`, `wait_for`, `wait`, `main_content_only`, `include_tags`, `exclude_tags`, `links`, `autoparse`, `extract`, `ai_extract` (coming soon), `screenshot`, `actions`, `session_id`, `cache`, `max_cost` and the other `/v1/scrape` fields. Note `render`/`format` instead of the API's `js_render`/`response_format`. `engine` and `headless` are not tool arguments; do not send them. |
 | `spicrawl_batch_submit` | Start an async job over many URLs (`urls` or `items`, plus shared settings such as `render`, `format`, `wait_for`). |
 | `spicrawl_batch_status` / `spicrawl_batch_list` | Poll one job / list jobs. |
 | `spicrawl_batch_results` | Read finished items (paged with `cursor`). |
 | `spicrawl_batch_task_content` | Get one item's full document by `job_id` and `seq`. |
 | `spicrawl_batch_add_items` / `spicrawl_batch_close` | Append to an `open` job / mark it complete. |
 | `spicrawl_batch_retry` / `spicrawl_batch_cancel` | Retry failed items / cancel a job (cannot be undone). |
-| `spicrawl_session_create` / `_list` / `_get` / `_context` / `_release` / `_delete` | Manage sessions (cookies, storage, engine). |
-| `spicrawl_browser_connect_url` | Coming soon: remote browser for Puppeteer/Playwright. Not available during the beta; do not use. |
+| `spicrawl_session_create` / `_list` / `_get` / `_context` / `_release` / `_delete` | Manage sessions (cookies, storage). |
+| `spicrawl_browser_connect_url` | Coming soon: remote browser for a CDP client. Not available during the beta; do not use. |
 | `spicrawl_requests_list` / `spicrawl_request_get` | Request history; look up a failure by request id. |
 | `spicrawl_usage` / `spicrawl_usage_summary` / `spicrawl_usage_reconciliation` | Credits and volume. Need the `read` scope. |
 | `spicrawl_docs_search` | Search Spicrawl's docs (`query`). Search an error code such as `ERR::PROXY::EXHAUSTED` to get its entry. |
@@ -141,9 +148,9 @@ Unknown fields are rejected with `400`: send only the fields below.
 | `url` | string | **Required.** The page to fetch. |
 | `response_format` | string | `markdown` (best for LLMs), `html`, `text`, `json` (envelope with metadata), `pdf`. |
 | `js_render` | bool | The content is built by JavaScript (SPA, empty HTML shell). |
-| `impersonate` | bool | Fetch tier only: present a current Chrome TLS/HTTP2 fingerprint. On by default and free; send `false` only to turn it off. |
-| `mode` | string | `auto` escalates fetch → obscura until one succeeds, billing only that rung. Not with `js_render` or `engine`. |
-| `engine` | string | Pin `fetch` / `obscura` / `chromium`. Not with `mode: auto`; `js_render` cannot pin `fetch`. |
+| `impersonate` | bool | Fetch tier only: present a current browser TLS/HTTP2 fingerprint. On by default and free; send `false` only to turn it off. |
+| `mode` | string | `auto` climbs from a plain fetch to JavaScript rendering, then full-browser rendering, then stealth rendering (coming soon), moving up only when the previous step was met by a challenge or a non-billable status, and bills only the step that served. Not with `js_render` or `stealth`. |
+| `engine` / `headless` | string / bool | **Deprecated, ignored.** Rendering is chosen automatically from `js_render`, `stealth`, `screenshot`, `actions`, `block_resources`, `response_format` and `mode`. Accepted so old clients keep working; they add `X-Warning: ENGINE_IGNORED`. Do not send them. |
 | `wait_for` / `wait_for_timeout` | string / int ms | CSS selector to wait for before capturing, and its cap. |
 | `wait` | int ms | Flat delay after load. |
 | `main_content_only` | bool | Strip nav, footer and aside (default on for markdown). |
@@ -153,7 +160,7 @@ Unknown fields are rejected with `400`: send only the fields below.
 | `extract` | object | Selector map, or a JSON Schema whose properties carry `selector`. |
 | `ai_extract` | object | `{"prompt": …}` **or** `{"schema": …}` (both is a 400). Coming soon: model-driven, +4 credits; refused with 503 `ERR::INTERNAL::UNAVAILABLE` until it launches. |
 | `network_capture` | object | Record the JSON the page itself fetched (XHR/fetch). Needs a render. |
-| `screenshot` | bool | Capture a screenshot (`screenshot_fullpage`, `screenshot_selector`, `screenshot_format`). Screenshots and `pdf` need a browser engine (`chromium`), not `mode: auto`. |
+| `screenshot` | bool | Capture a screenshot (`screenshot_fullpage`, `screenshot_selector`, `screenshot_format`). A screenshot, any `actions`, an explicit `block_resources` or `response_format: pdf` is routed to full-browser rendering for you; JavaScript rendering cannot do them. If the deployment has none: 400 `ERR::REQUEST::CAPABILITY_UNSUPPORTED`, 0 credits. |
 | `actions` | object[] | Browser workflow, at most 50 steps: `click`, `fill`, `wait_for`, `scroll`, `select`, `evaluate`, `screenshot`. |
 | `block_resources` | string[] | `images` `fonts` `media` `stylesheets` `scripts`, or `none`. |
 | `session_id` | string | Reuse a session's cookies and storage (see Sessions). Combine with `js_render` when you also send `actions` or `wait_for`. |
@@ -163,7 +170,7 @@ Unknown fields are rejected with `400`: send only the fields below.
 | `custom_headers` / `method` | object / string | Headers sent to the target (the field is `custom_headers`; `headers` is rejected). Default method `GET`. |
 | `allowed_status_codes` | int[] | Treat these target statuses as billable successes. |
 
-Coming soon, so do not send these yet: `ai_extract`, stealth mode (`stealth`, `engine: "camoufox"`), extraction presets (`extract_preset`), Spicrawl's managed proxy pool (`premium_proxy`, `proxy_country`, `sticky_key`, session `rotate_ip`/`region_pool`) and the remote browser (`/v1/browser`).
+Coming soon, so do not send these yet: `ai_extract`, stealth mode (`stealth`), extraction presets (`extract_preset`), Spicrawl's managed proxy pool (`premium_proxy`, `proxy_country`, `sticky_key`, session `rotate_ip`/`region_pool`) and the remote browser (`/v1/browser`).
 
 ### Structured extraction
 
@@ -192,7 +199,7 @@ in `empty_fields`. Extraction costs no extra credits, except `ai_extract`.
 ~~~json
 {
   "url": "https://example.com/login",
-  "engine": "chromium",
+  "js_render": true,
   "actions": [
     {"fill": {"selector": "#user", "value": "alice"}},
     {"fill": {"selector": "#pass", "value": "…", "secret": true}},
@@ -221,10 +228,10 @@ Every step accepts `label`, `timeout_ms` and `on_error` (`fail` or `skip`). `sec
 | `X-Credits-Charged` | Credits actually billed (`0` on any failure). |
 | `X-Request-Cost` | What it would have cost. |
 | `X-Credits-Remaining` | Monthly allowance left after this call (absent if the org has no limit). |
-| `X-Engine` | Engine that served it. |
+| `X-Engine` | The rendering tier that served it (informational): `fetch` (plain fetch), `js` (JavaScript rendering) or `browser` (full-browser rendering). The envelope's `engine` carries the same value. |
 | `X-Final-Url` | URL after redirects. |
 | `Cache-State` | `hit` (billed like the fetch that stored it), `miss` or `bypass`. |
-| `X-Warning` | Non-fatal decisions (a clamped `cache_ttl`, an ignored flag). |
+| `X-Warning` | Non-fatal decisions (a clamped `cache_ttl`, an ignored flag such as `ENGINE_IGNORED`, `ENGINE_SUBSTITUTED` when the deployment served the request with a different rendering tier than usual, `ESCALATED` naming each abandoned tier, its price and why). |
 | `X-RateLimit-Limit` / `-Remaining` / `-Reset` | Rate limit state. |
 
 ## Many URLs: `POST /v1/batch`
@@ -242,20 +249,24 @@ curl -sS -X POST https://api.spicrawl.com/v1/batch \
 
 Each item is one fetch or render, returned as `html`, `markdown` or `text`. Batch accepts
 the retrieval and cleaning fields (`response_format`, `js_render`, `impersonate`,
-`engine` of `fetch`/`obscura`, `proxy`,
+`proxy`,
 `proxy_verify`, `wait`, `wait_for`, `wait_for_timeout`, `block_resources`,
-`headless`, `custom_headers`, `main_content_only`, `include_tags`, `exclude_tags`, `max_cost`).
-It refuses with `400` (nothing queued, nothing charged): `extract`, `ai_extract`, `autoparse`,
-`actions`, `screenshot`, `network_capture`, `session_id`, `cache`, `links`, `mode: auto`,
-`response_format: pdf`, and `engine: chromium` (use `js_render: true`). Use `/v1/scrape` for those.
+`custom_headers`, `main_content_only`, `include_tags`, `exclude_tags`, `max_cost`).
+Items run as a plain fetch, JavaScript rendering (`js_render`) or stealth rendering (`stealth`, coming soon) only; `engine` is ignored
+and noted in the job's `warnings`. It refuses with `400` (nothing queued, nothing charged):
+`extract`, `ai_extract`, `autoparse`, `actions`, `screenshot` (a batch never uses full-browser rendering),
+`network_capture`, `session_id`, `cache`, `links`, `mode: auto` and `response_format: pdf`.
+Use `/v1/scrape` for those.
 
 1. Poll `GET /v1/batch/{id}` while `status` is `queued`, `running`, `paused` or `cancelling`
    (terminal: `completed`, `failed`, `cancelled`). Back off between polls.
 2. Read `GET /v1/batch/{id}/results?limit=100&cursor=…`. It is **JSONL** (one object per line);
    the next cursor is in the `X-Next-Cursor` header. Each line has `seq`, `url`, `status`,
    `http_status` and, once the item is done, `result` (`content`, `bytes`, `truncated`) or
-   `error` (`code`, `retryable`). `result.content` is the stored value as JSON text: decode it
-   once. For one item's full document, use `GET /v1/batch/{id}/tasks/{seq}/content`.
+   `error` (`code`, `retryable`). `result.content` is the page as plain text in the item's
+   `response_format` (for `json`, the JSON document as a string: parse it once). Do not decode it
+   again. For one item's full document, use `GET /v1/batch/{id}/tasks/{seq}/content`, which
+   returns it as a JSON string literal.
 3. Results expire after **72 hours** (`410 Gone`).
 4. Other routes: `POST /v1/batch/{id}/cancel`, `/retry` (failed items), `/items` (append to an
    `open: true` job), `/close` (finish an open job).
@@ -266,7 +277,7 @@ Keep cookies and storage across requests (log in once, then scrape).
 
 | Route | Purpose |
 |---|---|
-| `POST /v1/sessions` | Create (`engine`, `ttl_seconds`, `session_context`). |
+| `POST /v1/sessions` | Create (`ttl_seconds`, `session_context`). The session stays on the rendering path chosen for it. |
 | `GET /v1/sessions` / `GET /v1/sessions/{id}` | List / fetch. |
 | `GET /v1/sessions/{id}/context` | Captured cookies and storage. |
 | `POST /v1/sessions/{id}/release` | End it: permanently purges its cookies and storage (`409 ERR::SESSION::BUSY` while in use; `?force=true` overrides). |
@@ -277,7 +288,7 @@ a time. A concurrent request gets `ERR::SESSION::BUSY` (retryable).
 
 ## Live browser: `GET /v1/browser` (CDP)
 
-Coming soon: connect Puppeteer or Playwright to a Spicrawl-hosted browser. Not available during the beta.
+Coming soon: connect a CDP client to a Spicrawl-hosted browser. Not available during the beta.
 When it is: 8 credits per started minute, and the session's whole `session_ttl` is held against the
 allowance while it is open (24 credits for the default 3 minutes); unused minutes come back at close.
 
@@ -292,13 +303,20 @@ allowance while it is open (24 credits for the default 3 minutes); unused minute
 
 ## Credits
 
-| Engine | Credits |
-|---|---|
-| `fetch` | 1 |
-| `obscura` | 3 |
-| `chromium` | 8 |
-
-You pay for the engine that actually served (`X-Engine`). `ai_extract` adds +4. **Failures cost
+| Rendering tier | Credits (direct / datacenter / your own `proxy`) | Residential / mobile (managed premium exits, coming soon) |
+|---|---|---|
+| Plain fetch | 1 | 10 |
+| JavaScript rendering (`js_render`) | 3 | 25 |
+| Full-browser rendering (screenshot, PDF, `actions`, `block_resources`, anti-bot escalation) | 8 | 32 |
+| Stealth rendering (coming soon) | 25 | 25 |
+
+You pay for the tier that actually served (`X-Engine`), and you do not choose it: plain
+requests run as a plain fetch, `js_render` as JavaScript rendering, a screenshot or PDF as
+full-browser rendering. When a page shows a bot challenge (Cloudflare, DataDome, Akamai,
+PerimeterX) on your own `http://` `proxy`, Spicrawl moves to a stronger rendering path on
+the same exit by itself (managed premium exits: coming soon), billed only for the tier that
+returned the page, 0 if every step was challenged. On the default shared pool a challenged page
+returns `ERR::UPSTREAM::CHALLENGE`. `ai_extract` adds +4. **Failures cost
 0.** A cache hit is billed at the same price as the fetch that stored it. The cache saves the
 fetch (latency and load on the target), not credits. A deployment may discount these prices:
 `X-Credits-Charged` and `X-Request-Cost` are authoritative.
@@ -325,11 +343,13 @@ Errors are RFC 7807 JSON (`application/problem+json`):
 - Not retryable: `ERR::REQUEST::*`, `ERR::AUTH::*`, `ERR::SECURITY::*` (private or blocked
   target), and a failing custom `proxy` (`ERR::PROXY::UNREACHABLE`, `ERR::PROXY::AUTH_FAILED`).
 - `ERR::UPSTREAM::CHALLENGE` means an anti-bot page (Cloudflare, DataDome, Akamai…). Retry
-  once, then `js_render: true`, then the user's own `proxy` if they have one.
+  once, then the user's own residential `proxy`: through it Spicrawl moves to a stronger
+  rendering path by itself. Add `js_render: true` if the page also needs JavaScript. Success is
+  not guaranteed; a failure costs 0.
 - `ERR::LIMIT::QUOTA_EXCEEDED` (HTTP 402) means the organization's monthly allowance cannot cover
   this request. Nothing was charged. Waiting does not help until the reset: stop and tell the user,
   including the reset date (in the `detail`, or `allowance.resets_at` in the usage summary). A
-  cheaper request (a lower engine, fewer batch URLs) may still fit.
+  cheaper request (no render, fewer batch URLs) may still fit.
 - `ERR::INTERNAL::UNAVAILABLE` with `retryable: false` means the feature (for example
   `ai_extract`) is not configured on this deployment: don't retry.
 - The API is **not idempotent**: a retried scrape is billed again. Only retry a failure, and
@@ -340,7 +360,7 @@ Errors are RFC 7807 JSON (`application/problem+json`):
 1. Start cheap: `{"url": …, "response_format": "markdown"}` (1 credit).
 2. Check the site's status (`X-Target-Status`), not just the HTTP status.
 3. Empty or skeleton content → `js_render: true` (or `mode: "auto"`).
-4. Blocked or challenged → retry, then the user's own `proxy`; still blocked → stop and report.
+4. Blocked or challenged → retry once, then the user's own residential `proxy`; still blocked → stop and report.
 5. Need fields, not prose → `autoparse: true` first, then an `extract` schema (`ai_extract` is coming soon).
 6. More than about 20 URLs → a batch job (or `spicrawl scrape -` with `--concurrency`), not a loop.
 7. Cap spend with `max_cost`; track it with `X-Credits-Charged`.
diff --git a/internal/cmd/batch.go b/internal/cmd/batch.go
index 8e53b87..1eda27c 100644
--- a/internal/cmd/batch.go
+++ b/internal/cmd/batch.go
@@ -45,7 +45,7 @@ var batchSubmitScrapeFlags = map[string]string{
 	"render":           "",
 	"stealth":          "",
 	"impersonate":      "",
-	"engine":           "pin the engine: fetch|obscura|camoufox (chromium is refused on batch)",
+	"engine":           "",
 	"premium-proxy":    "",
 	"country":          "",
 	"proxy":            "",
@@ -54,7 +54,7 @@ var batchSubmitScrapeFlags = map[string]string{
 	"wait-for":         "CSS selector to wait for (needs --render or --stealth)",
 	"wait-for-timeout": "",
 	"block":            "",
-	"headless":         "rendered items: --headless=false runs with a real display",
+	"headless":         "",
 	"header":           "",
 	"main-content":     "",
 	"no-main-content":  "",
@@ -287,7 +287,7 @@ func batchWaitAndPrint(cmd *cobra.Command, c *api.Client, p *output.Printer, id
 		}
 		if werr == nil && (job.Status == "failed" || job.Status == "cancelled") {
 			msg := fmt.Sprintf("batch %s %s (%d of %d items finished)", id, job.Status, job.Progress.Completed, job.Progress.Total)
-			if e := strings.TrimSpace(job.ErrorCode + " " + job.ErrorMessage); e != "" {
+			if e := strings.TrimSpace(job.ErrorCode + " " + output.PublicText(job.ErrorMessage)); e != "" {
 				msg += ": " + e
 			}
 			return &ExitError{Code: exitcode.Request, Err: errors.New(msg)}
@@ -582,7 +582,7 @@ func batchHumanJob(w io.Writer, j batchJob) {
 	kv("finished", j.FinishedAt)
 	kv("results", batchIf(j.ResultsExpireAt != "", "readable until "+j.ResultsExpireAt))
 	if j.ErrorCode != "" || j.ErrorMessage != "" {
-		kv("error", strings.TrimSpace(j.ErrorCode+" "+j.ErrorMessage))
+		kv("error", output.PublicText(strings.TrimSpace(j.ErrorCode+" "+j.ErrorMessage)))
 	}
 }
 
diff --git a/internal/cmd/batch_test.go b/internal/cmd/batch_test.go
index a9b54ce..bab1261 100644
--- a/internal/cmd/batch_test.go
+++ b/internal/cmd/batch_test.go
@@ -359,8 +359,11 @@ func TestBatchSubmitRegistersOnlyAcceptedScrapeFlags(t *testing.T) {
 	if fl := f.Lookup("wait"); fl == nil || fl.Value.Type() != "bool" {
 		t.Errorf("--wait must stay the boolean job wait: %+v", fl)
 	}
-	if u := f.Lookup("engine").Usage; strings.Contains(u, "chromium|") || !strings.Contains(u, "refused") {
-		t.Errorf("--engine help should not offer chromium: %q", u)
+	// The API ignores engine and headless: still accepted, no longer advertised.
+	for _, name := range []string{"engine", "headless"} {
+		if !f.Lookup(name).Hidden {
+			t.Errorf("--%s should be hidden: the API ignores it", name)
+		}
 	}
 
 	srv, reqs := newRecordingServer(t, func(w http.ResponseWriter, r *http.Request) {})
@@ -388,7 +391,7 @@ func TestBatchSubmitAcceptedFlagsMapToFields(t *testing.T) {
 	_, errOut, code := batchRunCLI(t, srv.URL, "batch", "submit", urls, "--render", "--render-wait", "1500",
 		"--wait-for", "#price", "--wait-for-timeout", "4000", "--format", "markdown", "--main-content",
 		"--include", "main", "--exclude", "nav", "--header", "X-Trace: abc", "--headless=false",
-		"--impersonate", "--sticky-key", "k1", "--max-cost", "5", "--engine", "obscura")
+		"--impersonate", "--sticky-key", "k1", "--max-cost", "5", "--engine", "js")
 	if code != 0 {
 		t.Fatalf("exit %d: %s", code, errOut)
 	}
@@ -397,7 +400,7 @@ func TestBatchSubmitAcceptedFlagsMapToFields(t *testing.T) {
 		"urls": "[https://example.com/1]", "js_render": true, "wait": 1500.0, "wait_for": "#price",
 		"wait_for_timeout": 4000.0, "response_format": "markdown", "main_content_only": true,
 		"include_tags": "[main]", "exclude_tags": "[nav]", "custom_headers": "map[X-Trace:abc]",
-		"headless": false, "impersonate": true, "sticky_key": "k1", "max_cost": 5.0, "engine": "obscura",
+		"headless": false, "impersonate": true, "sticky_key": "k1", "max_cost": 5.0, "engine": "js",
 	}
 	for k, v := range want {
 		if fmt.Sprint(body[k]) != fmt.Sprint(v) {
diff --git a/internal/cmd/browser.go b/internal/cmd/browser.go
index 4cde7d7..e6ec4b2 100644
--- a/internal/cmd/browser.go
+++ b/internal/cmd/browser.go
@@ -26,17 +26,16 @@ var (
 
 var browserCmd = &cobra.Command{
 	Use:   "browser",
-	Short: "Cloud browsers over the Chrome DevTools Protocol",
-	Example: `  spicrawl browser url --engine chromium --country de
-  puppeteer_ws=$(spicrawl browser url --json | jq -r .url)`,
+	Short: "Cloud browsers over a DevTools Protocol (CDP) WebSocket",
+	Example: `  spicrawl browser url --engine browser --country de
+  cdp_ws=$(spicrawl browser url --json | jq -r .url)`,
 }
 
 var browserURLCmd = &cobra.Command{
 	Use:   "url",
 	Short: "Mint a single-use wss:// CDP URL for a cloud browser (no API key in it)",
-	Long: `Mint a connect URL for GET /v1/browser. Connect Puppeteer, Playwright or
-any CDP client to it; the browser starts when the socket opens and is billed
-from then.
+	Long: `Mint a connect URL for GET /v1/browser. Connect any CDP client to it; the
+browser starts when the socket opens and is billed from then.
 
 The command calls POST /v1/browser/token with your API key in the
 Authorization header and prints a URL that carries a short-lived token
@@ -51,8 +50,8 @@ Unlike sessions, the exit rotates unless you pass --sticky-key.
 a server without a cloud browser it exits 8 ("cloud browser (CDP) is not enabled
 on this server").`,
 	Example: `  spicrawl browser url
-  spicrawl browser url --engine obscura --region eu --ttl 600
-  spicrawl browser url --country us --headless=false --sticky-key crawl-1
+  spicrawl browser url --engine js --region eu --ttl 600
+  spicrawl browser url --country us --sticky-key crawl-1
   export SPICRAWL_BROWSER_URL="$(spicrawl browser url -q)"   # -q: the bare URL, even when piped
   WS=$(spicrawl browser url --json | jq -r .url)`,
 	Args: cobra.NoArgs,
@@ -61,8 +60,14 @@ on this server").`,
 		body := map[string]any{}
 		engine := strings.ToLower(browserEngine)
 		if f.Changed("engine") {
-			if engine != "chromium" && engine != "obscura" {
-				return Usagef("--engine must be chromium or obscura (fetch and camoufox do not speak CDP)")
+			switch {
+			case engine == "browser" || engine == "js":
+			case engine == "chromium" || engine == "obscura":
+				// Names from before tiers: the API still honours them, so they
+				// are sent as typed. The notice does not repeat the name.
+				Printer().Warn("--engine: this value is deprecated; use browser or js")
+			default:
+				return Usagef("--engine must be browser or js (fetch runs no browser, so it cannot speak CDP)")
 			}
 			body["engine"] = engine
 		}
@@ -85,8 +90,8 @@ on this server").`,
 			body["session_ttl"] = browserTTL
 		}
 		if f.Changed("headless") {
-			if !browserHeadless && engine == "obscura" {
-				return Usagef("--headless=false is not available with --engine obscura")
+			if !browserHeadless && (engine == "js" || engine == "obscura") {
+				return Usagef("--headless=false is not available with --engine js")
 			}
 			body["headless"] = browserHeadless
 		}
@@ -153,8 +158,7 @@ on this server").`,
 // browserHints shows how to connect. The URL is single-use, so mint it right
 // before connecting.
 const browserHints = `export SPICRAWL_BROWSER_URL="$(spicrawl browser url -q)"
-Puppeteer:  const browser = await puppeteer.connect({ browserWSEndpoint: process.env.SPICRAWL_BROWSER_URL });
-Playwright: const browser = await chromium.connectOverCDP(process.env.SPICRAWL_BROWSER_URL);`
+Connect your CDP client to $SPICRAWL_BROWSER_URL (a wss:// WebSocket endpoint).`
 
 // browserWSURL joins the API base URL and the token path the API returned,
 // switching the scheme to ws/wss. The base URL is used rather than the API's
@@ -197,13 +201,15 @@ func browserStickyKeyOK(k string) bool {
 
 func init() {
 	f := browserURLCmd.Flags()
-	f.StringVar(&browserEngine, "engine", "chromium", "browser: chromium|obscura")
+	f.StringVar(&browserEngine, "engine", "browser", "rendering tier of the browser: browser|js")
 	f.StringVar(&browserCountry, "country", "", "exit country, ISO 3166-1 alpha-2 (proxy_country)")
 	f.StringVar(&browserRegion, "region", "", "broad exit region such as eu (proxy_region)")
 	f.IntVar(&browserTTL, "ttl", 180, "hard session lifetime in seconds, 60-900 (session_ttl)")
-	f.BoolVar(&browserHeadless, "headless", true, "--headless=false attaches a display (chromium only)")
+	f.BoolVar(&browserHeadless, "headless", true, "attach a display to the browser (not with --engine js)")
 	f.StringVar(&browserStickyKey, "sticky-key", "", "pin the exit for the session (default: rotates)")
 
+	_ = f.MarkHidden("headless") // wire name of a display option; not advertised
+
 	browserCmd.AddCommand(browserURLCmd)
 	rootCmd.AddCommand(browserCmd)
 }
diff --git a/internal/cmd/browser_test.go b/internal/cmd/browser_test.go
index ae5a12a..9a619c1 100644
--- a/internal/cmd/browser_test.go
+++ b/internal/cmd/browser_test.go
@@ -62,14 +62,14 @@ func (f *fakeTokenAPI) server(t *testing.T) *httptest.Server {
 func TestBrowserURLMintsATokenAndNeverPrintsTheKey(t *testing.T) {
 	api := &fakeTokenAPI{}
 	srv := api.server(t)
-	out, errb, code := runCLI(t, srv.URL, "browser", "url", "--engine", "obscura", "--region", "EU", "--ttl", "600", "--sticky-key", "crawl-1")
+	out, errb, code := runCLI(t, srv.URL, "browser", "url", "--engine", "js", "--region", "EU", "--ttl", "600", "--sticky-key", "crawl-1")
 	if code != 0 {
 		t.Fatalf("exit %d: %s", code, errb)
 	}
 	if api.auth != "Bearer spicrawl_test_key" {
 		t.Errorf("Authorization = %q, want the key in the header", api.auth)
 	}
-	want := map[string]any{"engine": "obscura", "proxy_region": "eu", "session_ttl": float64(600), "sticky_key": "crawl-1"}
+	want := map[string]any{"engine": "js", "proxy_region": "eu", "session_ttl": float64(600), "sticky_key": "crawl-1"}
 	for k, v := range want {
 		if api.body[k] != v {
 			t.Errorf("body %s = %v, want %v", k, api.body[k], v)
@@ -102,6 +102,25 @@ func TestBrowserURLMintsATokenAndNeverPrintsTheKey(t *testing.T) {
 	}
 }
 
+// Engine names from before tiers still work: they reach the API as typed, with
+// a notice on stderr that does not repeat them.
+func TestBrowserURLLegacyEngineNamesStillWork(t *testing.T) {
+	for _, legacy := range []string{"chromium", "obscura"} {
+		api := &fakeTokenAPI{}
+		srv := api.server(t)
+		_, errb, code := runCLI(t, srv.URL, "browser", "url", "--engine", legacy)
+		if code != 0 {
+			t.Fatalf("%s: exit %d: %s", legacy, code, errb)
+		}
+		if api.body["engine"] != legacy {
+			t.Errorf("%s: sent engine %v", legacy, api.body["engine"])
+		}
+		if !strings.Contains(errb, "warning: --engine: this value is deprecated; use browser or js") || strings.Contains(errb, legacy) {
+			t.Errorf("%s: stderr %q", legacy, errb)
+		}
+	}
+}
+
 func TestBrowserWSURLSchemes(t *testing.T) {
 	for base, want := range map[string]string{
 		"https://api.example.test/": "wss://api.example.test/v1/browser?token=wbt_x",
@@ -123,8 +142,10 @@ func TestBrowserURLUsageErrors(t *testing.T) {
 	srv := api.server(t)
 	for _, args := range [][]string{
 		{"--country", "de", "--region", "eu"},
+		{"--engine", "fetch"},
 		{"--engine", "camoufox"},
 		{"--ttl", "30"},
+		{"--engine", "js", "--headless=false"},
 		{"--engine", "obscura", "--headless=false"},
 		{"--sticky-key", "bad_key"},
 	} {
@@ -151,7 +172,7 @@ func TestBrowserURLHumanHintsAndWSWarning(t *testing.T) {
 	if !strings.Contains(errb, "unencrypted") || !strings.Contains(errb, "works once") {
 		t.Errorf("stderr %q", errb)
 	}
-	if !strings.Contains(errb, "connectOverCDP(process.env.SPICRAWL_BROWSER_URL)") {
+	if !strings.Contains(errb, "Connect your CDP client to $SPICRAWL_BROWSER_URL") {
 		t.Errorf("hints missing: %s", errb)
 	}
 
@@ -159,7 +180,7 @@ func TestBrowserURLHumanHintsAndWSWarning(t *testing.T) {
 	if code != 0 || strings.Count(out, "\n") != 1 {
 		t.Errorf("quiet: exit %d stdout %q", code, out)
 	}
-	if strings.Contains(errb, "connectOverCDP") {
+	if strings.Contains(errb, "CDP client") {
 		t.Errorf("quiet printed hints: %s", errb)
 	}
 }
diff --git a/internal/cmd/engine_names_test.go b/internal/cmd/engine_names_test.go
new file mode 100644
index 0000000..919e482
--- /dev/null
+++ b/internal/cmd/engine_names_test.go
@@ -0,0 +1,225 @@
+package cmd
+
+import (
+	"bytes"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"regexp"
+	"strings"
+	"testing"
+
+	"github.com/spf13/cobra"
+
+	"github.com/OfficialSpicrawl/cli/internal/schema"
+)
+
+// Product rule: a customer never reads an engine or browser name (internalNames,
+// live_test.go) from the CLI. Engine routing is internal; the public vocabulary
+// is the tier: fetch, js, browser. These tests lock that for the text the CLI
+// writes, whatever the API sends. Machine output (--json, --jsonl) is the API's
+// own data and stays as sent.
+
+// wireField is the one name the API's own specs and skill keep: `headless` is a
+// wire field of the API (deprecated and ignored on scrape and batch; a /v1/browser
+// option). Everything else in them is tier vocabulary.
+var wireField = regexp.MustCompile(`\bheadless\b`)
+
+func TestHelpNeverNamesAnEngine(t *testing.T) {
+	var walk func(c *cobra.Command)
+	walk = func(c *cobra.Command) {
+		var buf bytes.Buffer
+		c.SetOut(&buf)
+		c.SetErr(&buf)
+		if err := c.Help(); err != nil {
+			t.Fatalf("%s: %v", c.CommandPath(), err)
+		}
+		c.SetOut(nil)
+		c.SetErr(nil)
+		if m := internalNames.FindString(buf.String()); m != "" {
+			t.Errorf("%q --help names %q:\n%s", c.CommandPath(), m, buf.String())
+		}
+		for _, sub := range c.Commands() {
+			walk(sub)
+		}
+	}
+	walk(rootCmd)
+}
+
+// The scrape flags the API ignores stay accepted, so no script breaks, but are
+// not advertised.
+func TestIgnoredEngineFlagsAreHidden(t *testing.T) {
+	for _, c := range []*cobra.Command{scrapeCmd, batchSubmitCmd, browserURLCmd} {
+		if fl := c.Flags().Lookup("headless"); fl == nil || !fl.Hidden {
+			t.Errorf("%s --headless must exist and be hidden: %+v", c.CommandPath(), fl)
+		}
+	}
+	for _, c := range []*cobra.Command{scrapeCmd, batchSubmitCmd} {
+		if fl := c.Flags().Lookup("engine"); fl == nil || !fl.Hidden {
+			t.Errorf("%s --engine must exist and be hidden: %+v", c.CommandPath(), fl)
+		}
+	}
+	// sessions and browser url take a tier, and say so.
+	for c, want := range map[*cobra.Command]string{sessionsCreateCmd: "fetch|js|browser", browserURLCmd: "browser|js"} {
+		fl := c.Flags().Lookup("engine")
+		if fl == nil || fl.Hidden || !strings.Contains(fl.Usage, want) {
+			t.Errorf("%s --engine should list %s: %+v", c.CommandPath(), want, fl)
+		}
+	}
+}
+
+func TestEmbeddedTextNeverNamesAnEngine(t *testing.T) {
+	if m := internalNames.FindString(wireField.ReplaceAllString(string(skillEmbedded), "")); m != "" {
+		t.Errorf("the embedded skill names %q", m)
+	}
+	spec, err := os.ReadFile("../../openapi.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if m := internalNames.FindString(wireField.ReplaceAllString(string(spec), "")); m != "" {
+		t.Errorf("openapi.yaml names %q (make spec refreshes it from the docs site)", m)
+	}
+	for _, name := range schema.Names() {
+		b, _ := schema.Get(name)
+		if m := internalNames.FindString(wireField.ReplaceAllString(string(b), "")); m != "" {
+			t.Errorf("schema %s names %q", name, m)
+		}
+	}
+}
+
+const leakyID = "01J9ZQ4M7R3T8VX2K5N6P0B1CD"
+
+// leakyAPI answers like an API from before tiers (or one with a bug): the engine
+// fields and the prose all name engines.
+func leakyAPI(t *testing.T) *httptest.Server {
+	t.Helper()
+	reply := func(status int, body string) http.HandlerFunc {
+		return func(w http.ResponseWriter, _ *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.WriteHeader(status)
+			fmt.Fprint(w, body)
+		}
+	}
+	session := func(engine string) string {
+		return `{"id":"` + leakyID + `","project_id":"p","engine":"` + engine + `","status":"active","sticky_key":"s1",` +
+			`"proxy":{"tier":"residential","country":"de"},"created_at":"2026-09-22T00:00:00Z","last_used_at":null,` +
+			`"expires_at":"2026-09-22T02:00:00Z","usage_count":0,"context":null,"warnings":["Moli cannot persist IndexedDB, use Chromium"]}`
+	}
+	entry := func(engine string) string {
+		return `{"id":"01M0FK1EP2E7FBMWAR7W10SMXW","created_at":"2026-09-22T10:00:00Z","project_id":"p","status":"failed","http_status":502,` +
+			`"engine":"` + engine + `","credits_micro":0,"url":"https://example.com/a","error_code":"ERR::ENGINE::FAILED",` +
+			`"error_detail":"Camoufox crashed; retried on Obscura","spans":{"total_ms":210},"proxy":{"source":"pool"},` +
+			`"blocked":{"vendor":"cloudflare","rule":"headless-check","signal":"Browserless"}}`
+	}
+	mux := http.NewServeMux()
+	mux.HandleFunc("POST /v1/scrape", func(w http.ResponseWriter, r *http.Request) {
+		h := w.Header()
+		h.Set("Content-Type", "text/markdown; charset=utf-8")
+		h.Set("X-Engine", "chromium")
+		h.Set("X-Credits-Charged", "8")
+		h.Set("X-Request-Cost", "8")
+		h.Set("X-Target-Status", "200")
+		h.Set("X-Proxy-Source", "pool")
+		h.Set("Cache-State", "miss")
+		h.Set("X-Request-Id", "01REQ")
+		h.Add("X-Warning", "ENGINE_FALLBACK: Camoufox was busy, served by Moli")
+		fmt.Fprint(w, "# Hello\n")
+	})
+	mux.HandleFunc("POST /v1/sessions", reply(201, session("obscura")))
+	mux.HandleFunc("GET /v1/sessions", reply(200, `{"sessions":[`+session("camoufox")+`,`+session("moli")+`]}`))
+	mux.HandleFunc("GET /v1/sessions/{id}", reply(200, session("chromium")))
+	mux.HandleFunc("GET /v1/requests", reply(200, `{"data":[`+entry("moli")+`],"page":{"has_more":false,"retention_hours":24}}`))
+	mux.HandleFunc("GET /v1/requests/{id}", reply(200, entry("chromium")))
+	mux.HandleFunc("GET /v1/usage", reply(200, `{"period":{"start":"2026-08-01","end":"2026-09-01","days":31},"group_by":"engine","groups":[`+
+		`{"key":"fetch","label":"Fetch","metrics":{"requests":40}},{"key":"chromium","label":"","metrics":{"requests":5}},`+
+		`{"key":"moli","label":"Moli renders","metrics":{"requests":2}}],"totals":{"requests":47},"unattributed":{"requests":0},"warnings":["no rows for Obscura"]}`))
+	srv := httptest.NewServer(mux)
+	t.Cleanup(srv.Close)
+	return srv
+}
+
+func TestHumanOutputNeverNamesAnEngine(t *testing.T) {
+	srv := leakyAPI(t)
+	cases := []struct {
+		name string
+		args []string
+		want []string // tier names the person should read instead
+	}{
+		{"scrape --meta", []string{"scrape", "https://example.com", "--meta"}, []string{"engine: browser", "served by js"}},
+		{"sessions create", []string{"sessions", "create"}, []string{"engine:", "js"}},
+		{"sessions list", []string{"sessions", "list"}, []string{"ENGINE", "browser", "js"}},
+		{"sessions get", []string{"sessions", "get", leakyID}, []string{"engine:", "browser"}},
+		{"logs", []string{"logs"}, []string{"ENGINE", "js"}},
+		{"logs get", []string{"logs", "get", "x"}, []string{"engine:", "browser", "browser crashed; retried on js"}},
+		{"usage by engine", []string{"usage", "--group-by", "engine"}, []string{"browser", "js renders", "no rows for js"}},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			out, errb, code := runHuman(t, srv.URL, false, tc.args...)
+			if code != 0 {
+				t.Fatalf("exit %d: %s", code, errb)
+			}
+			all := ansi.ReplaceAllString(out+errb, "")
+			if m := internalNames.FindString(all); m != "" {
+				t.Errorf("names %q:\n%s", m, all)
+			}
+			for _, w := range tc.want {
+				if !strings.Contains(all, w) {
+					t.Errorf("lacks %q:\n%s", w, all)
+				}
+			}
+		})
+	}
+}
+
+// The live terminal output (spinner, summary line) and the error block too.
+func TestLiveOutputAndErrorsNeverNameAnEngine(t *testing.T) {
+	srv := leakyAPI(t)
+	_, errb, code := runHuman(t, srv.URL, true, "scrape", "https://example.com", "--render")
+	if code != 0 {
+		t.Fatalf("exit %d: %s", code, errb)
+	}
+	plain := ansi.ReplaceAllString(errb, "")
+	if m := internalNames.FindString(plain); m != "" || !strings.Contains(plain, "✓ example.com") {
+		t.Errorf("live stderr (%q):\n%s", m, plain)
+	}
+
+	fail := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Content-Type", "application/problem+json")
+		w.WriteHeader(502)
+		fmt.Fprint(w, `{"title":"Bad Gateway","status":502,"code":"ERR::ENGINE::FAILED","detail":"Chromium did not answer","retryable":false,`+
+			`"diagnostics":{"hint":"retry, or drop stealth: Camoufox is busy"}}`)
+	}))
+	t.Cleanup(fail.Close)
+	for _, live := range []bool{false, true} {
+		_, errb, code = runHuman(t, fail.URL, live, "scrape", "https://example.com")
+		if code == 0 {
+			t.Fatal("want a failure")
+		}
+		plain = ansi.ReplaceAllString(errb, "")
+		if m := internalNames.FindString(plain); m != "" || !strings.Contains(plain, "browser did not answer") {
+			t.Errorf("live=%v error output (%q):\n%s", live, m, plain)
+		}
+	}
+}
+
+// Machine output is the API's data: nothing is rewritten, so a script sees what
+// the API sent.
+func TestJSONOutputStaysAsTheAPISentIt(t *testing.T) {
+	srv := leakyAPI(t)
+	for _, tc := range []struct {
+		args []string
+		want string
+	}{
+		{[]string{"sessions", "get", leakyID}, `"engine": "chromium"`},
+		{[]string{"scrape", "https://example.com"}, `"engine": "chromium"`},
+		{[]string{"logs", "--jsonl"}, `"engine":"moli"`},
+		{[]string{"usage", "--group-by", "engine"}, `"key": "chromium"`},
+	} {
+		out, errb, code := runCLI(t, srv.URL, tc.args...)
+		if code != 0 || !strings.Contains(out, tc.want) {
+			t.Errorf("%v: exit %d, want %s in:\n%s\n%s", tc.args, code, tc.want, out, errb)
+		}
+	}
+}
diff --git a/internal/cmd/logs.go b/internal/cmd/logs.go
index cbc9350..4505bfa 100644
--- a/internal/cmd/logs.go
+++ b/internal/cmd/logs.go
@@ -11,6 +11,7 @@ import (
 	"github.com/spf13/cobra"
 
 	"github.com/OfficialSpicrawl/cli/internal/api"
+	"github.com/OfficialSpicrawl/cli/internal/output"
 	"github.com/OfficialSpicrawl/cli/internal/ui"
 )
 
@@ -191,7 +192,7 @@ Status is one of: success, failed, timeout, blocked, rejected, cancelled.
 					row = append(row, logsDash(e.ProjectID))
 				}
 				rows = append(rows, append(row,
-					e.Status, logsOptInt(e.HTTPStatus), logsDash(e.Engine),
+					e.Status, logsOptInt(e.HTTPStatus), logsDash(output.Tier(e.Engine)),
 					logsCredits(e.CreditsMicro), logsSpan(e.Spans.Total), e.URL,
 				))
 			}
@@ -286,10 +287,10 @@ func logsWriteEntry(w io.Writer, u *ui.UI, e *logsEntry) {
 	kv("status", e.Status)
 	kv("url", e.URL)
 	kv("http status", logsOptInt(e.HTTPStatus))
-	kv("engine", logsDash(e.Engine))
+	kv("engine", logsDash(output.Tier(e.Engine)))
 	kv("credits", logsCredits(e.CreditsMicro))
 	kv("error", e.ErrorCode)
-	kv("error detail", e.ErrorDetail)
+	kv("error detail", output.PublicText(e.ErrorDetail))
 	if e.Attempts > 0 {
 		kv("attempts", strconv.Itoa(e.Attempts))
 	}
@@ -332,9 +333,9 @@ func logsWriteEntry(w io.Writer, u *ui.UI, e *logsEntry) {
 
 	if e.Blocked != nil {
 		fmt.Fprintln(w, "\n"+u.Bold("blocked:"))
-		pkv("vendor", logsDash(e.Blocked.Vendor))
-		pkv("rule", e.Blocked.Rule)
-		pkv("signal", e.Blocked.Signal)
+		pkv("vendor", logsDash(output.PublicText(e.Blocked.Vendor)))
+		pkv("rule", output.PublicText(e.Blocked.Rule))
+		pkv("signal", output.PublicText(e.Blocked.Signal))
 	}
 }
 
diff --git a/internal/cmd/ops_golden_test.go b/internal/cmd/ops_golden_test.go
index bf3c944..8356baf 100644
--- a/internal/cmd/ops_golden_test.go
+++ b/internal/cmd/ops_golden_test.go
@@ -72,7 +72,7 @@ const (
 		`"usage_as_of":"2026-09-22T06:00:00Z","stale_seconds":120,"warnings":["rollup is partial for 2026-08-03"]}`
 
 	gUsageEngine = `{"period":{"start":"2026-08-01","end":"2026-09-01","days":31,"bounds":"[start, end)"},"group_by":"engine","groups":[` +
-		`{"key":"fetch","label":"Fetch","metrics":{"requests":40,"credits":40000000}},{"key":"chromium","label":"","metrics":{"requests":5,"credits":25000000}}],` +
+		`{"key":"fetch","label":"Fetch","metrics":{"requests":40,"credits":40000000}},{"key":"browser","label":"Browser rendering","metrics":{"requests":5,"credits":25000000}}],` +
 		`"totals":{"requests":47,"credits":66000000},"unattributed":{"requests":2,"credits":1000000},"usage_as_of":null,"stale_seconds":7200}`
 
 	gUsageKey = `{"period":{"start":"2026-08-01","end":"2026-09-01","days":31,"bounds":"[start, end)"},"group_by":"key","keys":[` +
@@ -166,7 +166,7 @@ func init() {
 }
 
 func gBrowser(status int) func() http.HandlerFunc {
-	h := gJSON(200, `{"path":"/v1/browser?token=wbt_testtoken&engine=chromium&proxy_country=de","expires_at":"2026-09-22T06:01:00Z"}`)
+	h := gJSON(200, `{"path":"/v1/browser?token=wbt_testtoken&engine=browser&proxy_country=de","expires_at":"2026-09-22T06:01:00Z"}`)
 	if status == 501 {
 		h = gProblem(501, "ERR::ENGINE::UNAVAILABLE", "cloud browser is not enabled")
 	}
diff --git a/internal/cmd/root.go b/internal/cmd/root.go
index b6bbedc..b6102b6 100644
--- a/internal/cmd/root.go
+++ b/internal/cmd/root.go
@@ -272,10 +272,10 @@ func report(err error) int {
 			p.Out = p.Err
 			_ = p.Value(prob)
 		} else if u := p.UI(); u.On() {
-			u.Fail(prob.Error(), append(problemRows(prob), failRows...)...)
+			u.Fail(output.PublicText(prob.Error()), append(problemRows(prob), failRows...)...)
 		} else {
-			fmt.Fprintf(stderr, "error: %s\n", prob.Error())
-			if h := prob.Hint(); h != "" {
+			fmt.Fprintf(stderr, "error: %s\n", output.PublicText(prob.Error()))
+			if h := output.PublicText(prob.Hint()); h != "" {
 				fmt.Fprintf(stderr, "hint: %s\n", h)
 			}
 			if prob.TargetStatus != nil {
@@ -312,7 +312,7 @@ func failContext(rows ...ui.Row) { failRows = append(failRows, rows...) }
 // problemRows are the facts under an API error's headline on a terminal: the
 // same ones the plain output lists, the ERR:: code stays in the headline.
 func problemRows(prob *api.Problem) []ui.Row {
-	rows := []ui.Row{{Key: "hint", Val: prob.Hint()}}
+	rows := []ui.Row{{Key: "hint", Val: output.PublicText(prob.Hint())}}
 	if prob.TargetStatus != nil {
 		rows = append(rows, ui.Row{Key: "target", Val: fmt.Sprintf("returned %d", *prob.TargetStatus)})
 	}
diff --git a/internal/cmd/scrape.go b/internal/cmd/scrape.go
index 8ba68d5..282f547 100644
--- a/internal/cmd/scrape.go
+++ b/internal/cmd/scrape.go
@@ -505,7 +505,11 @@ func (r *scrapeResult) printMeta(p *output.Printer) {
 		}
 		return "-"
 	}
-	fmt.Fprintf(p.Err, "engine: %s\n", get("X-Engine", "engine"))
+	engine := get("X-Engine", "engine")
+	if engine != "-" {
+		engine = output.Tier(engine)
+	}
+	fmt.Fprintf(p.Err, "engine: %s\n", engine)
 	fmt.Fprintf(p.Err, "credits: %s (request cost %s)\n", get("X-Credits-Charged", "credits"), get("X-Request-Cost", "request_cost"))
 	fmt.Fprintf(p.Err, "cache: %s\n", get("Cache-State", "cache_state"))
 	fmt.Fprintf(p.Err, "target status: %s\n", get("X-Target-Status", "status"))
@@ -792,12 +796,13 @@ func scrapeErrorObject(err error) (any, int) {
 
 // scrapeLabel is the spinner text for one scrape: the page, and what the user
 // asked the API to do that makes it slow. Only what the request says is shown,
-// never the tier the API picks, and never an engine name.
+// never the tier the API picks, and never an engine name. A pinned "engine" is
+// not shown: the API ignores it.
 func scrapeLabel(target string, body map[string]any) string {
 	label := "Scraping " + scrapeShortURL(target)
 	var does []string
 	switch {
-	case body["stealth"] == true, scrapeBrowserEngine(body["engine"]), body["actions"] != nil:
+	case body["stealth"] == true, body["actions"] != nil:
 		does = append(does, "using a full browser")
 	case body["js_render"] == true:
 		does = append(does, "rendering JavaScript")
@@ -811,12 +816,6 @@ func scrapeLabel(target string, body map[string]any) string {
 	return label
 }
 
-// scrapeBrowserEngine reports whether a pinned engine is a browser.
-func scrapeBrowserEngine(v any) bool {
-	e, _ := v.(string)
-	return e != "" && e != "fetch"
-}
-
 // scrapeShortURL is host and path without the scheme, query or fragment.
 func scrapeShortURL(raw string) string {
 	u, err := url.Parse(raw)
diff --git a/internal/cmd/scrape_test.go b/internal/cmd/scrape_test.go
index e4664c9..0b3e4cb 100644
--- a/internal/cmd/scrape_test.go
+++ b/internal/cmd/scrape_test.go
@@ -156,7 +156,7 @@ func TestScrapeEnvelopePassthrough(t *testing.T) {
 
 func TestScrapeOutputFileAndScreenshots(t *testing.T) {
 	png := []byte("\x89PNG fake")
-	env := map[string]any{"url": "https://example.com", "content": "# Page", "status": 200, "engine": "chromium",
+	env := map[string]any{"url": "https://example.com", "content": "# Page", "status": 200, "engine": "browser",
 		"screenshots": []any{map[string]any{"label": "final", "encoding": "base64", "format": "png",
 			"data": base64.StdEncoding.EncodeToString(png), "size_bytes": len(png)}}}
 	srv, _ := newRecordingServer(t, func(w http.ResponseWriter, _ *http.Request) {
diff --git a/internal/cmd/scrapeflags.go b/internal/cmd/scrapeflags.go
index a9a784f..17db7f6 100644
--- a/internal/cmd/scrapeflags.go
+++ b/internal/cmd/scrapeflags.go
@@ -35,9 +35,9 @@ func addScrapeFlags(cmd *cobra.Command) *scrapeFlags {
 	f.StringVar(&s.format, "format", "", "response_format: html|markdown|text|json|pdf")
 	f.StringVar(&s.method, "method", "", "HTTP method sent to the target (default GET)")
 	f.BoolVar(&s.render, "render", false, "render JavaScript in a browser (js_render)")
-	f.BoolVar(&s.stealth, "stealth", false, "hardened browser fingerprint (camoufox; dearest tier)")
+	f.BoolVar(&s.stealth, "stealth", false, "full-browser rendering hardened against bot detection (dearest tier)")
 	f.BoolVar(&s.impersonate, "impersonate", false, "fetch tier: present a real browser TLS/HTTP2 fingerprint (on by default; --impersonate=false turns it off)")
-	f.StringVar(&s.engine, "engine", "", "pin the engine: fetch|obscura|chromium|camoufox")
+	f.StringVar(&s.engine, "engine", "", "ignored: the API chooses the rendering tier")
 	f.StringVar(&s.mode, "mode", "", "auto: escalate through tiers until one succeeds")
 	f.BoolVar(&s.premium, "premium-proxy", false, "residential exits (priced higher; fails rather than falling back)")
 	f.StringVar(&s.country, "country", "", "proxy_country, ISO 3166-1 alpha-2 lowercase (needs --premium-proxy)")
@@ -49,7 +49,7 @@ func addScrapeFlags(cmd *cobra.Command) *scrapeFlags {
 	f.StringVar(&s.waitFor, "wait-for", "", "CSS selector to wait for")
 	f.IntVar(&s.waitForTimeout, "wait-for-timeout", 0, "cap on --wait-for, ms")
 	f.StringSliceVar(&s.block, "block", nil, "block_resources: images,fonts,media,stylesheets,scripts or none")
-	f.BoolVar(&s.headless, "headless", true, "chromium only: --headless=false runs with a real display")
+	f.BoolVar(&s.headless, "headless", true, "ignored: the API chooses how the page is rendered")
 	f.StringArrayVar(&s.headers, "header", nil, "custom header sent to the target, 'Name: value' (repeatable)")
 	f.StringVar(&s.extract, "extract", "", "selector map or JSON Schema, as JSON or @file")
 	f.StringVar(&s.aiPrompt, "ai", "", "ai_extract prompt: describe the data in plain language")
@@ -74,6 +74,10 @@ func addScrapeFlags(cmd *cobra.Command) *scrapeFlags {
 	f.StringSliceVar(&s.allowedStatus, "allowed-status", nil, "extra target statuses to accept, e.g. 403: billed as a success (200/404/410 always are), ends --mode auto escalation, and scrape exits 0 instead of 6 on them")
 	f.BoolVar(&s.originalStatus, "original-status", false, "API answers with the target's status on its HTTP status line (the CLI reads the target status either way)")
 	f.StringVar(&s.body, "body", "", "raw request body as JSON or @file; flags override its fields (nested objects are merged key by key)")
+	// The API ignores both and says so in a warning, so they are kept (scripts
+	// that pass them still work) but not advertised.
+	_ = f.MarkHidden("engine")
+	_ = f.MarkHidden("headless")
 	return s
 }
 
diff --git a/internal/cmd/sessions.go b/internal/cmd/sessions.go
index b70c894..dd8214e 100644
--- a/internal/cmd/sessions.go
+++ b/internal/cmd/sessions.go
@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"net/url"
 	"os"
+	"slices"
 	"strconv"
 	"strings"
 
@@ -62,9 +63,9 @@ var (
 var sessionsCmd = &cobra.Command{
 	Use:   "sessions",
 	Short: "Persisted browser sessions (cookies and storage reused across scrapes)",
-	Long: `Sessions keep one engine, one exit and one cookie jar across many scrapes.
+	Long: `Sessions keep one rendering tier, one exit and one cookie jar across many scrapes.
 Pass a session's id to "spicrawl scrape --session ID".`,
-	Example: `  spicrawl sessions create --engine chromium --ttl 7200 --country de
+	Example: `  spicrawl sessions create --engine browser --ttl 7200 --country de
   spicrawl sessions list --status active
   spicrawl sessions release 01J9ZQ4M7R3T8VX2K5N6P0B1CD`,
 }
@@ -73,8 +74,8 @@ var sessionsCreateCmd = &cobra.Command{
 	Use:   "create",
 	Short: "Create a session (POST /v1/sessions)",
 	Long: `Create a session. Only flags you set are sent; the API applies its defaults
-(engine: first of obscura, chromium available; ttl 1800 s; exit pinned to the
-session id).
+(tier: chosen for you unless --engine names one; ttl 1800 s; exit pinned to
+the session id).
 
 --country needs the residential tier, so it implies --premium-proxy.
 --rotate-ip keeps the cookie jar but lets the exit IP change; it cannot be
@@ -84,15 +85,15 @@ context object {"cookies": [...], "local_storage": {...}, "session_storage":
 {...}, "indexed_db": {...}}, or the output of "spicrawl sessions context --json",
 whose session_context member is sent.`,
 	Example: `  # Pinned residential exit in Germany for two hours
-  spicrawl sessions create --engine chromium --ttl 7200 --country de
+  spicrawl sessions create --engine browser --ttl 7200 --country de
 
   # A crawl that keeps cookies but rotates IPs
-  spicrawl sessions create --engine obscura --rotate-ip
+  spicrawl sessions create --engine js --rotate-ip
 
   # Import a saved login (cookies, local/session storage). Takes either a bare
   # context object or what "spicrawl sessions context ID --json" printed.
   spicrawl sessions context 01J9ZQ4M7R3T8VX2K5N6P0B1CD --json > login.json
-  spicrawl sessions create --engine chromium --session-context login.json
+  spicrawl sessions create --engine browser --session-context login.json
 
   # Capture the id for later scrapes
   SID=$(spicrawl sessions create --json | jq -r .id)`,
@@ -105,10 +106,14 @@ whose session_context member is sent.`,
 		body := map[string]any{}
 		if f.Changed("engine") {
 			e := strings.ToLower(sessionsEngine)
-			switch e {
-			case "fetch", "obscura", "chromium", "camoufox":
+			switch {
+			case slices.Contains([]string{"fetch", "js", "browser"}, e):
+			case slices.Contains([]string{"obscura", "chromium", "camoufox"}, e):
+				// Names from before tiers: the API still honours them, so they
+				// are sent as typed. The notice does not repeat the name.
+				Printer().Warn("--engine: this value is deprecated; use fetch, js or browser")
 			default:
-				return Usagef("--engine must be fetch, obscura, chromium or camoufox, not %q", sessionsEngine)
+				return Usagef("--engine must be fetch, js or browser, not %q", sessionsEngine)
 			}
 			body["engine"] = e
 		}
@@ -166,7 +171,7 @@ var sessionsListCmd = &cobra.Command{
 page can be short or empty and still have more behind it; --all keeps paging
 until the API says there are no more.`,
 	Example: `  spicrawl sessions list
-  spicrawl sessions list --status active --engine chromium --all
+  spicrawl sessions list --status active --engine browser --all
   spicrawl sessions list --json | jq -r '.sessions[].id'`,
 	Args: cobra.NoArgs,
 	RunE: func(cmd *cobra.Command, _ []string) error {
@@ -238,7 +243,7 @@ until the API says there are no more.`,
 				if s.Proxy.Country != "" {
 					exit += "/" + s.Proxy.Country
 				}
-				rows = append(rows, []string{s.ID, s.Engine, s.Status, exit, strconv.Itoa(s.UsageCount), s.ExpiresAt})
+				rows = append(rows, []string{s.ID, output.Tier(s.Engine), s.Status, exit, strconv.Itoa(s.UsageCount), s.ExpiresAt})
 			}
 			u := outUI(p)
 			viewTable(p, u, []string{"ID", "ENGINE", "STATUS", "EXIT", "USES", "EXPIRES"}, rows, func(col int, cell string) string {
@@ -439,7 +444,7 @@ func sessionsPrintOne(body []byte, created bool) error {
 	}
 	kv("id", s.ID)
 	kv("status", s.Status)
-	kv("engine", s.Engine)
+	kv("engine", output.Tier(s.Engine))
 	exit := s.Proxy.Tier
 	if s.Proxy.Country != "" {
 		exit += " (" + s.Proxy.Country + ")"
@@ -477,7 +482,7 @@ func sessionsStatusCell(u *ui.UI, s string) string {
 
 func init() {
 	cf := sessionsCreateCmd.Flags()
-	cf.StringVar(&sessionsEngine, "engine", "", "engine to pin: fetch|obscura|chromium|camoufox")
+	cf.StringVar(&sessionsEngine, "engine", "", "rendering tier to bind the session to: fetch|js|browser")
 	cf.IntVar(&sessionsTTL, "ttl", 0, "sliding lifetime in seconds (ttl_seconds, min 30, default 1800)")
 	cf.StringVar(&sessionsCountry, "country", "", "exit country, ISO 3166-1 alpha-2 (implies --premium-proxy)")
 	cf.BoolVar(&sessionsPremium, "premium-proxy", false, "residential exits instead of datacenter")
@@ -488,7 +493,7 @@ func init() {
 
 	lf := sessionsListCmd.Flags()
 	lf.IntVar(&sessionsListLimit, "limit", 50, "page size, 1-200")
-	lf.StringVar(&sessionsListEngine, "engine", "", "only sessions pinned to this engine")
+	lf.StringVar(&sessionsListEngine, "engine", "", "only sessions bound to this tier: fetch|js|browser")
 	lf.StringVar(&sessionsListStatus, "status", "", "only active|released|expired sessions")
 	lf.BoolVar(&sessionsListAll, "all", false, "follow next_cursor until every page is read")
 
diff --git a/internal/cmd/sessions_golden_test.go b/internal/cmd/sessions_golden_test.go
index 6decc8b..eb33ac9 100644
--- a/internal/cmd/sessions_golden_test.go
+++ b/internal/cmd/sessions_golden_test.go
@@ -8,15 +8,15 @@ import (
 const (
 	gSessionID = "01J9ZQ4M7R3T8VX2K5N6P0B1CD"
 
-	gSession = `{"id":"` + gSessionID + `","project_id":"proj_01J9Z","engine":"chromium","status":"active","sticky_key":"login-1",` +
+	gSession = `{"id":"` + gSessionID + `","project_id":"proj_01J9Z","engine":"browser","status":"active","sticky_key":"login-1",` +
 		`"proxy":{"tier":"residential","country":"de","region_pool":"eu"},"created_at":"2026-09-22T00:00:00Z","last_used_at":"2026-09-22T00:30:00Z",` +
 		`"expires_at":"2026-09-22T02:00:00Z","hard_expires_at":"2026-09-23T00:00:00Z","usage_count":7,"context":null}`
 
-	gSessionNew = `{"id":"` + gSessionID + `","project_id":"proj_01J9Z","engine":"obscura","status":"active","sticky_key":null,` +
+	gSessionNew = `{"id":"` + gSessionID + `","project_id":"proj_01J9Z","engine":"js","status":"active","sticky_key":null,` +
 		`"proxy":{"tier":"datacenter"},"created_at":"2026-09-22T00:00:00Z","last_used_at":null,"expires_at":"2026-09-22T00:30:00Z",` +
-		`"usage_count":0,"warnings":["engine obscura cannot persist IndexedDB"]}`
+		`"usage_count":0,"warnings":["ttl_seconds was reduced to this organization's maximum"]}`
 
-	gSessionReleased = `{"id":"` + gSessionID + `","project_id":"proj_01J9Z","engine":"chromium","status":"released","sticky_key":"login-1",` +
+	gSessionReleased = `{"id":"` + gSessionID + `","project_id":"proj_01J9Z","engine":"browser","status":"released","sticky_key":"login-1",` +
 		`"proxy":{"tier":"residential","country":"de"},"created_at":"2026-09-22T00:00:00Z","last_used_at":"2026-09-22T00:30:00Z",` +
 		`"expires_at":"2026-09-22T02:00:00Z","released_at":"2026-09-22T00:45:00Z","retired":"released by the caller","usage_count":7}`
 
@@ -33,7 +33,7 @@ func init() {
 	del := goldenServe(map[string]http.HandlerFunc{"DELETE /v1/sessions/{id}": func(w http.ResponseWriter, _ *http.Request) { w.WriteHeader(http.StatusNoContent) }})
 
 	goldenAdd(
-		goldenCase{name: "sessions/create", args: []string{"sessions", "create", "--engine", "obscura"}, server: one("POST", "/v1/sessions", gSessionNew, 201)},
+		goldenCase{name: "sessions/create", args: []string{"sessions", "create", "--engine", "js"}, server: one("POST", "/v1/sessions", gSessionNew, 201)},
 		goldenCase{name: "sessions/create_session_context_file", args: []string{"sessions", "create", "--session-context", "{dir}/ctx.json"}, server: one("POST", "/v1/sessions", gSession, 201),
 			setup: func(t *testing.T, e *goldenEnv) { goldenWrite(t, e.Dir, "ctx.json", gSessionContext) }},
 		goldenCase{name: "sessions/create_usage_error", args: []string{"sessions", "create", "--rotate-ip", "--sticky-key", "k1"}, stderr: true},
diff --git a/internal/cmd/sessions_test.go b/internal/cmd/sessions_test.go
index cc05d6c..e24d6ac 100644
--- a/internal/cmd/sessions_test.go
+++ b/internal/cmd/sessions_test.go
@@ -11,14 +11,14 @@ import (
 	"time"
 )
 
-const sessionsTestBody = `{"id":"01J9ZQ4M7R3T8VX2K5N6P0B1CD","project_id":"p","engine":"chromium","status":"active","sticky_key":"s1","proxy":{"tier":"residential","country":"de"},"created_at":"2026-09-22T00:00:00Z","last_used_at":null,"expires_at":"2026-09-22T02:00:00Z","usage_count":0,"context":null}`
+const sessionsTestBody = `{"id":"01J9ZQ4M7R3T8VX2K5N6P0B1CD","project_id":"p","engine":"browser","status":"active","sticky_key":"s1","proxy":{"tier":"residential","country":"de"},"created_at":"2026-09-22T00:00:00Z","last_used_at":null,"expires_at":"2026-09-22T02:00:00Z","usage_count":0,"context":null}`
 
 func TestSessionsCreateMapsFlags(t *testing.T) {
 	srv, reqs := newRecordingServer(t, func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusCreated)
 		_, _ = w.Write([]byte(sessionsTestBody))
 	})
-	out, errb, code := runCLI(t, srv.URL, "sessions", "create", "--engine", "Chromium", "--ttl", "7200", "--country", "DE", "--sticky-key", "login-1")
+	out, errb, code := runCLI(t, srv.URL, "sessions", "create", "--engine", "Browser", "--ttl", "7200", "--country", "DE", "--sticky-key", "login-1")
 	if code != 0 {
 		t.Fatalf("exit %d, stderr %s", code, errb)
 	}
@@ -28,7 +28,7 @@ func TestSessionsCreateMapsFlags(t *testing.T) {
 	}
 	var body map[string]any
 	_ = json.Unmarshal(r.Body, &body)
-	want := map[string]any{"engine": "chromium", "ttl_seconds": 7200.0, "proxy_country": "de", "premium_proxy": true, "sticky_key": "login-1"}
+	want := map[string]any{"engine": "browser", "ttl_seconds": 7200.0, "proxy_country": "de", "premium_proxy": true, "sticky_key": "login-1"}
 	if len(body) != len(want) {
 		t.Fatalf("body %v, want %v", body, want)
 	}
@@ -42,6 +42,34 @@ func TestSessionsCreateMapsFlags(t *testing.T) {
 	}
 }
 
+// Engine names from before tiers still work: sent as typed, with a notice that
+// does not repeat the name. Anything else is a usage error that lists the tiers.
+func TestSessionsCreateEngineTiersAndLegacyNames(t *testing.T) {
+	for _, legacy := range []string{"obscura", "chromium", "camoufox"} {
+		srv, reqs := newRecordingServer(t, func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusCreated)
+			_, _ = w.Write([]byte(sessionsTestBody))
+		})
+		_, errb, code := runCLI(t, srv.URL, "sessions", "create", "--engine", legacy)
+		if code != 0 {
+			t.Fatalf("%s: exit %d: %s", legacy, code, errb)
+		}
+		var body map[string]any
+		_ = json.Unmarshal((*reqs)[0].Body, &body)
+		if body["engine"] != legacy {
+			t.Errorf("%s: sent %v", legacy, body["engine"])
+		}
+		if !strings.Contains(errb, "warning: --engine: this value is deprecated; use fetch, js or browser") || strings.Contains(errb, legacy) {
+			t.Errorf("%s: stderr %q", legacy, errb)
+		}
+	}
+	srv, reqs := newRecordingServer(t, func(w http.ResponseWriter, r *http.Request) {})
+	_, errb, code := runCLI(t, srv.URL, "sessions", "create", "--engine", "nope")
+	if code != 2 || len(*reqs) != 0 || !strings.Contains(errb, "--engine must be fetch, js or browser") {
+		t.Errorf("exit %d, %d requests, stderr %q", code, len(*reqs), errb)
+	}
+}
+
 func TestSessionsCreateEmptyBody(t *testing.T) {
 	srv, reqs := newRecordingServer(t, func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusCreated)
@@ -71,14 +99,14 @@ func TestSessionsListAllFollowsCursor(t *testing.T) {
 		}
 		_, _ = w.Write([]byte(`{"sessions":[` + sessionsTestBody + `]}`))
 	})
-	out, errb, code := runCLI(t, srv.URL, "sessions", "list", "--all", "--status", "active", "--engine", "chromium", "--limit", "1")
+	out, errb, code := runCLI(t, srv.URL, "sessions", "list", "--all", "--status", "active", "--engine", "browser", "--limit", "1")
 	if code != 0 {
 		t.Fatalf("exit %d: %s", code, errb)
 	}
 	if len(*reqs) != 2 {
 		t.Fatalf("%d requests, want 2", len(*reqs))
 	}
-	if q := (*reqs)[0].Query; q != "engine=chromium&limit=1&status=active" {
+	if q := (*reqs)[0].Query; q != "engine=browser&limit=1&status=active" {
 		t.Errorf("first query %q", q)
 	}
 	if q := (*reqs)[1].Query; !strings.Contains(q, "cursor=1790000000000000000.ABC") {
diff --git a/internal/cmd/testdata/golden/browser/url.stdout b/internal/cmd/testdata/golden/browser/url.stdout
index 6b234ac..d986e88 100644
--- a/internal/cmd/testdata/golden/browser/url.stdout
+++ b/internal/cmd/testdata/golden/browser/url.stdout
@@ -1,5 +1,5 @@
 {
   "expires_at": "<TIMESTAMP>",
   "single_use": true,
-  "url": "ws://SERVER/v1/browser?token=wbt_testtoken&engine=chromium&proxy_country=de"
+  "url": "ws://SERVER/v1/browser?token=wbt_testtoken&engine=browser&proxy_country=de"
 }
diff --git a/internal/cmd/testdata/golden/browser/url_quiet_json.stdout b/internal/cmd/testdata/golden/browser/url_quiet_json.stdout
index 6b234ac..d986e88 100644
--- a/internal/cmd/testdata/golden/browser/url_quiet_json.stdout
+++ b/internal/cmd/testdata/golden/browser/url_quiet_json.stdout
@@ -1,5 +1,5 @@
 {
   "expires_at": "<TIMESTAMP>",
   "single_use": true,
-  "url": "ws://SERVER/v1/browser?token=wbt_testtoken&engine=chromium&proxy_country=de"
+  "url": "ws://SERVER/v1/browser?token=wbt_testtoken&engine=browser&proxy_country=de"
 }
diff --git a/internal/cmd/testdata/golden/browser/url_quiet_prints_bare_url.stdout b/internal/cmd/testdata/golden/browser/url_quiet_prints_bare_url.stdout
index c1c624d..8421e8c 100644
--- a/internal/cmd/testdata/golden/browser/url_quiet_prints_bare_url.stdout
+++ b/internal/cmd/testdata/golden/browser/url_quiet_prints_bare_url.stdout
@@ -1 +1 @@
-ws://SERVER/v1/browser?token=wbt_testtoken&engine=chromium&proxy_country=de
+ws://SERVER/v1/browser?token=wbt_testtoken&engine=browser&proxy_country=de
diff --git a/internal/cmd/testdata/golden/browser_human/url.stdout b/internal/cmd/testdata/golden/browser_human/url.stdout
index c1c624d..8421e8c 100644
--- a/internal/cmd/testdata/golden/browser_human/url.stdout
+++ b/internal/cmd/testdata/golden/browser_human/url.stdout
@@ -1 +1 @@
-ws://SERVER/v1/browser?token=wbt_testtoken&engine=chromium&proxy_country=de
+ws://SERVER/v1/browser?token=wbt_testtoken&engine=browser&proxy_country=de
diff --git a/internal/cmd/testdata/golden/schema/batch.stdout.sha256 b/internal/cmd/testdata/golden/schema/batch.stdout.sha256
index e3a3e98..ba43ba0 100644
--- a/internal/cmd/testdata/golden/schema/batch.stdout.sha256
+++ b/internal/cmd/testdata/golden/schema/batch.stdout.sha256
@@ -1,2 +1,2 @@
-sha256 266998850ee3992e4bd07755021c5f11ec6077c02834d03c83da88898731eb2a
-bytes 102977
+sha256 9d3b83e5167fb4cc32b14c04d0b0b35bc3923af4a9bc54854c9ecd7259e57fb8
+bytes 101849
diff --git a/internal/cmd/testdata/golden/schema/batch_item.stdout.sha256 b/internal/cmd/testdata/golden/schema/batch_item.stdout.sha256
index ae9bbaf..8152054 100644
--- a/internal/cmd/testdata/golden/schema/batch_item.stdout.sha256
+++ b/internal/cmd/testdata/golden/schema/batch_item.stdout.sha256
@@ -1,2 +1,2 @@
-sha256 9039dfe91d5728ae8bf229ddd0560d651b27fbd3c73fb64a14915f5f36a09f9a
-bytes 48426
+sha256 350e8cc661cb858b9ff8cee4dd239a6e35ecae0f540d03d3f43bdd6672f301e6
+bytes 47874
diff --git a/internal/cmd/testdata/golden/schema/scrape.stdout.sha256 b/internal/cmd/testdata/golden/schema/scrape.stdout.sha256
index 5b7dc24..a573c48 100644
--- a/internal/cmd/testdata/golden/schema/scrape.stdout.sha256
+++ b/internal/cmd/testdata/golden/schema/scrape.stdout.sha256
@@ -1,2 +1,2 @@
-sha256 676f4b8f19ba42a3665e03dc792447ae0d0f7994212b5aa6a38eeaaaf6491de8
-bytes 47911
+sha256 125c298e36efc791dc7d3d11304680d4efe1281a1c51aa683de9329b88f36a31
+bytes 47636
diff --git a/internal/cmd/testdata/golden/schema/session.stdout.sha256 b/internal/cmd/testdata/golden/schema/session.stdout.sha256
index c53e2ef..b5d1240 100644
--- a/internal/cmd/testdata/golden/schema/session.stdout.sha256
+++ b/internal/cmd/testdata/golden/schema/session.stdout.sha256
@@ -1,2 +1,2 @@
-sha256 ec7f95d65b603dca6468abb8aec21ca1acc14905ab47d6843c2633d9b6c7e16e
-bytes 8827
+sha256 b550ba2dad0a6bf2fbe372f7475862e8ba5ad82dc410cd0b3df9048bdac94973
+bytes 8867
diff --git a/internal/cmd/testdata/golden/schema_human/batch.stdout.sha256 b/internal/cmd/testdata/golden/schema_human/batch.stdout.sha256
index e3a3e98..ba43ba0 100644
--- a/internal/cmd/testdata/golden/schema_human/batch.stdout.sha256
+++ b/internal/cmd/testdata/golden/schema_human/batch.stdout.sha256
@@ -1,2 +1,2 @@
-sha256 266998850ee3992e4bd07755021c5f11ec6077c02834d03c83da88898731eb2a
-bytes 102977
+sha256 9d3b83e5167fb4cc32b14c04d0b0b35bc3923af4a9bc54854c9ecd7259e57fb8
+bytes 101849
diff --git a/internal/cmd/testdata/golden/schema_human/batch_item.stdout.sha256 b/internal/cmd/testdata/golden/schema_human/batch_item.stdout.sha256
index ae9bbaf..8152054 100644
--- a/internal/cmd/testdata/golden/schema_human/batch_item.stdout.sha256
+++ b/internal/cmd/testdata/golden/schema_human/batch_item.stdout.sha256
@@ -1,2 +1,2 @@
-sha256 9039dfe91d5728ae8bf229ddd0560d651b27fbd3c73fb64a14915f5f36a09f9a
-bytes 48426
+sha256 350e8cc661cb858b9ff8cee4dd239a6e35ecae0f540d03d3f43bdd6672f301e6
+bytes 47874
diff --git a/internal/cmd/testdata/golden/schema_human/scrape.stdout.sha256 b/internal/cmd/testdata/golden/schema_human/scrape.stdout.sha256
index 5b7dc24..a573c48 100644
--- a/internal/cmd/testdata/golden/schema_human/scrape.stdout.sha256
+++ b/internal/cmd/testdata/golden/schema_human/scrape.stdout.sha256
@@ -1,2 +1,2 @@
-sha256 676f4b8f19ba42a3665e03dc792447ae0d0f7994212b5aa6a38eeaaaf6491de8
-bytes 47911
+sha256 125c298e36efc791dc7d3d11304680d4efe1281a1c51aa683de9329b88f36a31
+bytes 47636
diff --git a/internal/cmd/testdata/golden/schema_human/session.stdout.sha256 b/internal/cmd/testdata/golden/schema_human/session.stdout.sha256
index c53e2ef..b5d1240 100644
--- a/internal/cmd/testdata/golden/schema_human/session.stdout.sha256
+++ b/internal/cmd/testdata/golden/schema_human/session.stdout.sha256
@@ -1,2 +1,2 @@
-sha256 ec7f95d65b603dca6468abb8aec21ca1acc14905ab47d6843c2633d9b6c7e16e
-bytes 8827
+sha256 b550ba2dad0a6bf2fbe372f7475862e8ba5ad82dc410cd0b3df9048bdac94973
+bytes 8867
diff --git a/internal/cmd/testdata/golden/sessions/create.stdout b/internal/cmd/testdata/golden/sessions/create.stdout
index 562dd8b..a54f635 100644
--- a/internal/cmd/testdata/golden/sessions/create.stdout
+++ b/internal/cmd/testdata/golden/sessions/create.stdout
@@ -1,7 +1,7 @@
 {
   "id": "01J9ZQ4M7R3T8VX2K5N6P0B1CD",
   "project_id": "proj_01J9Z",
-  "engine": "obscura",
+  "engine": "js",
   "status": "active",
   "sticky_key": null,
   "proxy": {
@@ -12,6 +12,6 @@
   "expires_at": "<TIMESTAMP>",
   "usage_count": 0,
   "warnings": [
-    "engine obscura cannot persist IndexedDB"
+    "ttl_seconds was reduced to this organization's maximum"
   ]
 }
diff --git a/internal/cmd/testdata/golden/sessions/create_session_context_file.stdout b/internal/cmd/testdata/golden/sessions/create_session_context_file.stdout
index c5b29c0..3767a58 100644
--- a/internal/cmd/testdata/golden/sessions/create_session_context_file.stdout
+++ b/internal/cmd/testdata/golden/sessions/create_session_context_file.stdout
@@ -1,7 +1,7 @@
 {
   "id": "01J9ZQ4M7R3T8VX2K5N6P0B1CD",
   "project_id": "proj_01J9Z",
-  "engine": "chromium",
+  "engine": "browser",
   "status": "active",
   "sticky_key": "login-1",
   "proxy": {
diff --git a/internal/cmd/testdata/golden/sessions/get.stdout b/internal/cmd/testdata/golden/sessions/get.stdout
index c5b29c0..3767a58 100644
--- a/internal/cmd/testdata/golden/sessions/get.stdout
+++ b/internal/cmd/testdata/golden/sessions/get.stdout
@@ -1,7 +1,7 @@
 {
   "id": "01J9ZQ4M7R3T8VX2K5N6P0B1CD",
   "project_id": "proj_01J9Z",
-  "engine": "chromium",
+  "engine": "browser",
   "status": "active",
   "sticky_key": "login-1",
   "proxy": {
diff --git a/internal/cmd/testdata/golden/sessions/list.stdout b/internal/cmd/testdata/golden/sessions/list.stdout
index 931ded3..f1527d6 100644
--- a/internal/cmd/testdata/golden/sessions/list.stdout
+++ b/internal/cmd/testdata/golden/sessions/list.stdout
@@ -3,7 +3,7 @@
     {
       "id": "01J9ZQ4M7R3T8VX2K5N6P0B1CD",
       "project_id": "proj_01J9Z",
-      "engine": "chromium",
+      "engine": "browser",
       "status": "active",
       "sticky_key": "login-1",
       "proxy": {
@@ -21,7 +21,7 @@
     {
       "id": "01J9ZQ4M7R3T8VX2K5N6P0B1CD",
       "project_id": "proj_01J9Z",
-      "engine": "chromium",
+      "engine": "browser",
       "status": "released",
       "sticky_key": "login-1",
       "proxy": {
diff --git a/internal/cmd/testdata/golden/sessions/list_all_pages.stdout b/internal/cmd/testdata/golden/sessions/list_all_pages.stdout
index 931ded3..f1527d6 100644
--- a/internal/cmd/testdata/golden/sessions/list_all_pages.stdout
+++ b/internal/cmd/testdata/golden/sessions/list_all_pages.stdout
@@ -3,7 +3,7 @@
     {
       "id": "01J9ZQ4M7R3T8VX2K5N6P0B1CD",
       "project_id": "proj_01J9Z",
-      "engine": "chromium",
+      "engine": "browser",
       "status": "active",
       "sticky_key": "login-1",
       "proxy": {
@@ -21,7 +21,7 @@
     {
       "id": "01J9ZQ4M7R3T8VX2K5N6P0B1CD",
       "project_id": "proj_01J9Z",
-      "engine": "chromium",
+      "engine": "browser",
       "status": "released",
       "sticky_key": "login-1",
       "proxy": {
diff --git a/internal/cmd/testdata/golden/sessions/list_next_cursor.stdout b/internal/cmd/testdata/golden/sessions/list_next_cursor.stdout
index e1a1240..51311a5 100644
--- a/internal/cmd/testdata/golden/sessions/list_next_cursor.stdout
+++ b/internal/cmd/testdata/golden/sessions/list_next_cursor.stdout
@@ -4,7 +4,7 @@
     {
       "id": "01J9ZQ4M7R3T8VX2K5N6P0B1CD",
       "project_id": "proj_01J9Z",
-      "engine": "chromium",
+      "engine": "browser",
       "status": "active",
       "sticky_key": "login-1",
       "proxy": {
diff --git a/internal/cmd/testdata/golden/sessions/release.stdout b/internal/cmd/testdata/golden/sessions/release.stdout
index aaea824..cf2bddc 100644
--- a/internal/cmd/testdata/golden/sessions/release.stdout
+++ b/internal/cmd/testdata/golden/sessions/release.stdout
@@ -1,7 +1,7 @@
 {
   "id": "01J9ZQ4M7R3T8VX2K5N6P0B1CD",
   "project_id": "proj_01J9Z",
-  "engine": "chromium",
+  "engine": "browser",
   "status": "released",
   "sticky_key": "login-1",
   "proxy": {
diff --git a/internal/cmd/testdata/golden/sessions_human/create.stdout b/internal/cmd/testdata/golden/sessions_human/create.stdout
index 69f419b..51ad7de 100644
--- a/internal/cmd/testdata/golden/sessions_human/create.stdout
+++ b/internal/cmd/testdata/golden/sessions_human/create.stdout
@@ -1,6 +1,6 @@
 id:              01J9ZQ4M7R3T8VX2K5N6P0B1CD
 status:          active
-engine:          obscura
+engine:          js
 exit:            datacenter
 sticky key:      (rotating)
 uses:            0
diff --git a/internal/cmd/testdata/golden/sessions_human/get.stdout b/internal/cmd/testdata/golden/sessions_human/get.stdout
index 20dce43..616d93f 100644
--- a/internal/cmd/testdata/golden/sessions_human/get.stdout
+++ b/internal/cmd/testdata/golden/sessions_human/get.stdout
@@ -1,6 +1,6 @@
 id:              01J9ZQ4M7R3T8VX2K5N6P0B1CD
 status:          active
-engine:          chromium
+engine:          browser
 exit:            residential (de) pool eu
 sticky key:      login-1
 uses:            7
diff --git a/internal/cmd/testdata/golden/sessions_human/get_released.stdout b/internal/cmd/testdata/golden/sessions_human/get_released.stdout
index a3d6efc..d06c25c 100644
--- a/internal/cmd/testdata/golden/sessions_human/get_released.stdout
+++ b/internal/cmd/testdata/golden/sessions_human/get_released.stdout
@@ -1,6 +1,6 @@
 id:              01J9ZQ4M7R3T8VX2K5N6P0B1CD
 status:          released
-engine:          chromium
+engine:          browser
 exit:            residential (de)
 sticky key:      login-1
 uses:            7
diff --git a/internal/cmd/testdata/golden/sessions_human/list.stdout b/internal/cmd/testdata/golden/sessions_human/list.stdout
index aa37fc0..2855349 100644
--- a/internal/cmd/testdata/golden/sessions_human/list.stdout
+++ b/internal/cmd/testdata/golden/sessions_human/list.stdout
@@ -1,3 +1,3 @@
-ID                          ENGINE    STATUS    EXIT            USES  EXPIRES
-01J9ZQ4M7R3T8VX2K5N6P0B1CD  chromium  active    residential/de  7     <TIMESTAMP>
-01J9ZQ4M7R3T8VX2K5N6P0B1CD  chromium  released  residential/de  7     <TIMESTAMP>
+ID                          ENGINE   STATUS    EXIT            USES  EXPIRES
+01J9ZQ4M7R3T8VX2K5N6P0B1CD  browser  active    residential/de  7     <TIMESTAMP>
+01J9ZQ4M7R3T8VX2K5N6P0B1CD  browser  released  residential/de  7     <TIMESTAMP>
diff --git a/internal/cmd/testdata/golden/sessions_human/list_next_cursor.stdout b/internal/cmd/testdata/golden/sessions_human/list_next_cursor.stdout
index 05429ad..cf665dd 100644
--- a/internal/cmd/testdata/golden/sessions_human/list_next_cursor.stdout
+++ b/internal/cmd/testdata/golden/sessions_human/list_next_cursor.stdout
@@ -1,2 +1,2 @@
-ID                          ENGINE    STATUS  EXIT            USES  EXPIRES
-01J9ZQ4M7R3T8VX2K5N6P0B1CD  chromium  active  residential/de  7     <TIMESTAMP>
+ID                          ENGINE   STATUS  EXIT            USES  EXPIRES
+01J9ZQ4M7R3T8VX2K5N6P0B1CD  browser  active  residential/de  7     <TIMESTAMP>
diff --git a/internal/cmd/testdata/golden/sessions_human/release.stdout b/internal/cmd/testdata/golden/sessions_human/release.stdout
index a3d6efc..d06c25c 100644
--- a/internal/cmd/testdata/golden/sessions_human/release.stdout
+++ b/internal/cmd/testdata/golden/sessions_human/release.stdout
@@ -1,6 +1,6 @@
 id:              01J9ZQ4M7R3T8VX2K5N6P0B1CD
 status:          released
-engine:          chromium
+engine:          browser
 exit:            residential (de)
 sticky key:      login-1
 uses:            7
diff --git a/internal/cmd/testdata/golden/usage_human/by_engine_unattributed.stdout b/internal/cmd/testdata/golden/usage_human/by_engine_unattributed.stdout
index c18b6a0..a199696 100644
--- a/internal/cmd/testdata/golden/usage_human/by_engine_unattributed.stdout
+++ b/internal/cmd/testdata/golden/usage_human/by_engine_unattributed.stdout
@@ -1,7 +1,7 @@
 period [2026-08-01, 2026-09-01) (31 days), by engine
 
-ENGINE          REQUESTS  CREDITS
-Fetch           40        40
-chromium        5         25
-(unattributed)  2         1
-TOTAL           47        66
+ENGINE             REQUESTS  CREDITS
+Fetch              40        40
+Browser rendering  5         25
+(unattributed)     2         1
+TOTAL              47        66
diff --git a/internal/cmd/usage.go b/internal/cmd/usage.go
index 960cbec..b2f2768 100644
--- a/internal/cmd/usage.go
+++ b/internal/cmd/usage.go
@@ -115,7 +115,9 @@ Needs a key with the read scope.`,
 		for _, g := range b.Groups {
 			key := g.Key
 			if g.Label != "" {
-				key = g.Label
+				key = output.PublicText(g.Label)
+			} else if b.GroupBy == "engine" {
+				key = output.Tier(g.Key) // the API groups by tier; a name from before tiers is mapped
 			}
 			rows = append(rows, append([]string{key}, usageCells(cols, g.Metrics)...))
 		}
diff --git a/internal/output/output.go b/internal/output/output.go
index 7ea9240..89791f4 100644
--- a/internal/output/output.go
+++ b/internal/output/output.go
@@ -107,15 +107,17 @@ func (p *Printer) Table(headers []string, rows [][]string) {
 	tw.Flush()
 }
 
-// Info writes a progress or status line to stderr unless --quiet.
+// Info writes a progress or status line to stderr unless --quiet. Like Warn it
+// shows server prose with tier names (PublicText).
 func (p *Printer) Info(format string, a ...any) {
 	if p.Quiet {
 		return
 	}
-	ui.Fprintf(p.Err, format+"\n", a...)
+	ui.Fprintf(p.Err, "%s", PublicText(fmt.Sprintf(format+"\n", a...)))
 }
 
-// Warn writes a warning to stderr, even with --quiet.
+// Warn writes a warning to stderr, even with --quiet. Server prose in it is
+// shown with tier names, never engine names (PublicText).
 func (p *Printer) Warn(format string, a ...any) {
-	ui.Fprintf(p.Err, "warning: "+format+"\n", a...)
+	ui.Fprintf(p.Err, "%s", PublicText(fmt.Sprintf("warning: "+format+"\n", a...)))
 }
diff --git a/internal/output/tier.go b/internal/output/tier.go
new file mode 100644
index 0000000..96cee01
--- /dev/null
+++ b/internal/output/tier.go
@@ -0,0 +1,48 @@
+package output
+
+import (
+	"regexp"
+	"strings"
+)
+
+// The rendering tiers a customer sees. Which engine serves a request is
+// internal; the API reports a tier and so does the CLI.
+const (
+	TierFetch   = "fetch"
+	TierJS      = "js"
+	TierBrowser = "browser"
+)
+
+// Tier is the public tier of an engine value, for human output. A tier maps to
+// itself; a name from before tiers maps as the API does (api/internal/router
+// Engine.Tier): moli, obscura and headless are js, fetch is fetch, and anything
+// else fails closed to browser instead of leaking its name. "" stays "".
+func Tier(engine string) string {
+	switch strings.ToLower(strings.TrimSpace(engine)) {
+	case "":
+		return ""
+	case TierFetch:
+		return TierFetch
+	case TierJS, "moli", "obscura", "headless":
+		return TierJS
+	}
+	return TierBrowser
+}
+
+// internalNames are the engine names a person never reads, the same set the API
+// rewrites (router.PublicText). "moli" is a whole word so it cannot hit the
+// middle of another word. Not "chrome", "playwright" or "puppeteer": those are
+// also the domains and package names a page can legitimately mention.
+var internalNames = regexp.MustCompile(`(?i)plain[ _-]?chrome|browserless|camoufox|chromium|obscura|headful|headless|\bmoli\b`)
+
+// PublicText rewrites internal names in server prose to their tier, as a net
+// under the API's own rewriting. Human output only: JSON stays as sent.
+func PublicText(s string) string {
+	return internalNames.ReplaceAllStringFunc(s, func(w string) string {
+		switch strings.ToLower(w) {
+		case "moli", "obscura", "headless":
+			return TierJS
+		}
+		return TierBrowser
+	})
+}
diff --git a/internal/output/tier_test.go b/internal/output/tier_test.go
new file mode 100644
index 0000000..ee38ea8
--- /dev/null
+++ b/internal/output/tier_test.go
@@ -0,0 +1,32 @@
+package output
+
+import "testing"
+
+func TestTier(t *testing.T) {
+	for in, want := range map[string]string{
+		"": "", "fetch": "fetch", "FETCH": "fetch",
+		"js": "js", "moli": "js", "Obscura": "js", "headless": "js",
+		"browser": "browser", "chromium": "browser", "chrome": "browser", "camoufox": "browser",
+		"browserless": "browser", "headful": "browser", "moli-chromium": "browser", "something-new": "browser",
+	} {
+		if got := Tier(in); got != want {
+			t.Errorf("Tier(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
+
+func TestPublicText(t *testing.T) {
+	for in, want := range map[string]string{
+		"served by Moli":                          "served by js",
+		"Chromium crashed; retried on Obscura":    "browser crashed; retried on js",
+		"plain Chrome and Browserless are slow":   "browser and browser are slow",
+		"headful camoufox, headless obscura":      "browser browser, js js",
+		"a molinillo and the evolution":           "a molinillo and the evolution",
+		"see https://playwright.dev/docs":         "see https://playwright.dev/docs",
+		"nothing to rewrite: 3 credits, fetch/js": "nothing to rewrite: 3 credits, fetch/js",
+	} {
+		if got := PublicText(in); got != want {
+			t.Errorf("PublicText(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
diff --git a/internal/schema/batch-item.json b/internal/schema/batch-item.json
index 8539042..a5fa841 100644
--- a/internal/schema/batch-item.json
+++ b/internal/schema/batch-item.json
@@ -6,7 +6,7 @@
   "allOf": [
     {
       "type": "object",
-      "description": "The /v1/scrape request object as accepted by batch, minus `url`. Field names, types and validation are exactly\nScrapeRequest's (enforced by a parity test); each property below references it. Every item is merged as\njob-level value, overridden by the item's value (an explicit `false` on an item wins), with the project's\ndashboard defaults underneath both. Validation happens for every item at submission.\n\nWhat the batch worker executes: each item is one fetch or one render, and the document is returned as\n`response_format` (`html` by default, `json`, `markdown` or `text`). A field is either honoured on a batch item\nor refused at submission, never accepted and skipped. Refused with 400 INVALID_PARAMETER, naming every offending\nfield, with nothing queued or charged: `actions`, `screenshot` and its options, `network_capture`, `extract`,\n`extract_preset`, `ai_extract`, `autoparse`, `links`, `session_id`, `cache`/`cache_ttl`, `original_status`,\n`allowed_status_codes`, `parse_pdf=true`, `mode=auto`, `response_format=pdf`, and a non-GET `method` with\n`js_render` or `stealth`. A value that asks for nothing (`screenshot: false`, an empty list) is accepted. A\nrefusal caused by a project default says so in `detail`. Use /v1/scrape for those fields.\n\nA batch item is priced when it is accepted, so a bot challenge never climbs it to camoufox or retries it on a\ndifferent exit the way it can a /v1/scrape request with `premium_proxy` or `proxy`.\n",
+      "description": "The /v1/scrape request object as accepted by batch, minus `url`. Field names, types and validation are exactly\nScrapeRequest's (enforced by a parity test); each property below references it. Every item is merged as\njob-level value, overridden by the item's value (an explicit `false` on an item wins), with the project's\ndashboard defaults underneath both. Validation happens for every item at submission.\n\nWhat the batch worker executes: each item is one fetch or one render, and the document is returned as\n`response_format` (`html` by default, `json`, `markdown` or `text`). A field is either honoured on a batch item\nor refused at submission, never accepted and skipped. Refused with 400 INVALID_PARAMETER, naming every offending\nfield, with nothing queued or charged: `actions`, `screenshot` and its options, `network_capture`, `extract`,\n`extract_preset`, `ai_extract`, `autoparse`, `links`, `session_id`, `cache`/`cache_ttl`, `original_status`,\n`allowed_status_codes`, `parse_pdf=true`, `mode=auto`, `response_format=pdf`, and a non-GET `method` with\n`js_render` or `stealth`. A value that asks for nothing (`screenshot: false`, an empty list) is accepted. A\nrefusal caused by a project default says so in `detail`. Use /v1/scrape for those fields.\n\nA batch item is priced when it is accepted, so a bot challenge never escalates it to stronger rendering or retries it on a\ndifferent exit the way it can a /v1/scrape request with your own `proxy`.\n",
       "properties": {
         "method": {
           "type": "string",
@@ -25,12 +25,12 @@
         "js_render": {
           "type": "boolean",
           "default": false,
-          "description": "Render the page with the obscura browser engine. Honoured by the batch worker. Default false (or the project default)."
+          "description": "Run the page's JavaScript before capture. Honoured by the batch worker. Default false (or the project default)."
         },
         "stealth": {
           "type": "boolean",
           "default": false,
-          "description": "Coming soon. Render with the camoufox anti-detection engine; takes precedence over `js_render`. Honoured by the batch worker. Default false (or the project default)."
+          "description": "Coming soon. Render with full-browser rendering hardened against bot detection; takes precedence over `js_render`. Honoured by the batch worker. Default false (or the project default)."
         },
         "impersonate": {
           "type": "boolean",
@@ -42,17 +42,12 @@
           "enum": [
             "auto"
           ],
-          "description": "`auto` is refused on batch with 400 INVALID_PARAMETER, also when it comes from the project defaults; the batch worker does not escalate. It runs the engine that `engine`, `js_render` or `stealth` selects."
+          "description": "`auto` is refused on batch with 400 INVALID_PARAMETER, also when it comes from the project defaults; the batch worker does not escalate. It runs the rendering that `js_render` or `stealth` selects."
         },
         "engine": {
           "type": "string",
-          "enum": [
-            "fetch",
-            "obscura",
-            "camoufox",
-            "chromium"
-          ],
-          "description": "Engine `camoufox` is coming soon.\nEngine pin. On batch only `fetch`, `obscura`, `camoufox` are allowed; `chromium` is rejected with 400\nINVALID_PARAMETER (use /v1/scrape for chromium). Also 400 INCOMPATIBLE_FLAGS for: `mode=auto` plus any pin;\n`stealth=true` with a pin other than camoufox; `js_render=true` with `fetch`; `screenshot=true` with `fetch`\nor `obscura`. A pin the plan does not include is 403 (plans whose entitlements cannot be read allow only\nfetch and obscura). To be sure the worker renders, set `js_render` (obscura) or `stealth` (camoufox) rather\nthan relying on the pin alone.\n"
+          "deprecated": true,
+          "description": "Deprecated and ignored; rendering is chosen automatically. The job's `warnings` report the ignored field."
         },
         "premium_proxy": {
           "type": "boolean",
@@ -542,7 +537,7 @@
               {
                 "type": "object",
                 "title": "screenshot",
-                "description": "Capture a screenshot mid-workflow (needs camoufox or chromium); returned under `screenshots` with this step's label.",
+                "description": "Capture a screenshot mid-workflow (needs full-browser rendering); returned under `screenshots` with this step's label.",
                 "required": [
                   "screenshot"
                 ],
@@ -649,11 +644,12 @@
               "other"
             ]
           },
-          "description": "Resource classes to block while rendering. Honoured on rendered items only; unset blocks images and fonts, `none` blocks nothing, a list replaces the default. Falls back to the project default when unset."
+          "description": "Resource classes to block while rendering. Honoured on rendered items only; unset blocks nothing on full-browser rendering, `none` blocks nothing, a list blocks the classes named. Falls back to the project default when unset."
         },
         "headless": {
           "type": "boolean",
-          "description": "Honoured on rendered items (the project default for headless is NOT merged on batch)."
+          "deprecated": true,
+          "description": "Deprecated and ignored. The browser mode is chosen automatically."
         },
         "screenshot": {
           "type": "boolean",
diff --git a/internal/schema/batch.json b/internal/schema/batch.json
index 8fa5733..e154b53 100644
--- a/internal/schema/batch.json
+++ b/internal/schema/batch.json
@@ -6,7 +6,7 @@
   "allOf": [
     {
       "type": "object",
-      "description": "The /v1/scrape request object as accepted by batch, minus `url`. Field names, types and validation are exactly\nScrapeRequest's (enforced by a parity test); each property below references it. Every item is merged as\njob-level value, overridden by the item's value (an explicit `false` on an item wins), with the project's\ndashboard defaults underneath both. Validation happens for every item at submission.\n\nWhat the batch worker executes: each item is one fetch or one render, and the document is returned as\n`response_format` (`html` by default, `json`, `markdown` or `text`). A field is either honoured on a batch item\nor refused at submission, never accepted and skipped. Refused with 400 INVALID_PARAMETER, naming every offending\nfield, with nothing queued or charged: `actions`, `screenshot` and its options, `network_capture`, `extract`,\n`extract_preset`, `ai_extract`, `autoparse`, `links`, `session_id`, `cache`/`cache_ttl`, `original_status`,\n`allowed_status_codes`, `parse_pdf=true`, `mode=auto`, `response_format=pdf`, and a non-GET `method` with\n`js_render` or `stealth`. A value that asks for nothing (`screenshot: false`, an empty list) is accepted. A\nrefusal caused by a project default says so in `detail`. Use /v1/scrape for those fields.\n\nA batch item is priced when it is accepted, so a bot challenge never climbs it to camoufox or retries it on a\ndifferent exit the way it can a /v1/scrape request with `premium_proxy` or `proxy`.\n",
+      "description": "The /v1/scrape request object as accepted by batch, minus `url`. Field names, types and validation are exactly\nScrapeRequest's (enforced by a parity test); each property below references it. Every item is merged as\njob-level value, overridden by the item's value (an explicit `false` on an item wins), with the project's\ndashboard defaults underneath both. Validation happens for every item at submission.\n\nWhat the batch worker executes: each item is one fetch or one render, and the document is returned as\n`response_format` (`html` by default, `json`, `markdown` or `text`). A field is either honoured on a batch item\nor refused at submission, never accepted and skipped. Refused with 400 INVALID_PARAMETER, naming every offending\nfield, with nothing queued or charged: `actions`, `screenshot` and its options, `network_capture`, `extract`,\n`extract_preset`, `ai_extract`, `autoparse`, `links`, `session_id`, `cache`/`cache_ttl`, `original_status`,\n`allowed_status_codes`, `parse_pdf=true`, `mode=auto`, `response_format=pdf`, and a non-GET `method` with\n`js_render` or `stealth`. A value that asks for nothing (`screenshot: false`, an empty list) is accepted. A\nrefusal caused by a project default says so in `detail`. Use /v1/scrape for those fields.\n\nA batch item is priced when it is accepted, so a bot challenge never escalates it to stronger rendering or retries it on a\ndifferent exit the way it can a /v1/scrape request with your own `proxy`.\n",
       "properties": {
         "method": {
           "type": "string",
@@ -25,12 +25,12 @@
         "js_render": {
           "type": "boolean",
           "default": false,
-          "description": "Render the page with the obscura browser engine. Honoured by the batch worker. Default false (or the project default)."
+          "description": "Run the page's JavaScript before capture. Honoured by the batch worker. Default false (or the project default)."
         },
         "stealth": {
           "type": "boolean",
           "default": false,
-          "description": "Coming soon. Render with the camoufox anti-detection engine; takes precedence over `js_render`. Honoured by the batch worker. Default false (or the project default)."
+          "description": "Coming soon. Render with full-browser rendering hardened against bot detection; takes precedence over `js_render`. Honoured by the batch worker. Default false (or the project default)."
         },
         "impersonate": {
           "type": "boolean",
@@ -42,17 +42,12 @@
           "enum": [
             "auto"
           ],
-          "description": "`auto` is refused on batch with 400 INVALID_PARAMETER, also when it comes from the project defaults; the batch worker does not escalate. It runs the engine that `engine`, `js_render` or `stealth` selects."
+          "description": "`auto` is refused on batch with 400 INVALID_PARAMETER, also when it comes from the project defaults; the batch worker does not escalate. It runs the rendering that `js_render` or `stealth` selects."
         },
         "engine": {
           "type": "string",
-          "enum": [
-            "fetch",
-            "obscura",
-            "camoufox",
-            "chromium"
-          ],
-          "description": "Engine `camoufox` is coming soon.\nEngine pin. On batch only `fetch`, `obscura`, `camoufox` are allowed; `chromium` is rejected with 400\nINVALID_PARAMETER (use /v1/scrape for chromium). Also 400 INCOMPATIBLE_FLAGS for: `mode=auto` plus any pin;\n`stealth=true` with a pin other than camoufox; `js_render=true` with `fetch`; `screenshot=true` with `fetch`\nor `obscura`. A pin the plan does not include is 403 (plans whose entitlements cannot be read allow only\nfetch and obscura). To be sure the worker renders, set `js_render` (obscura) or `stealth` (camoufox) rather\nthan relying on the pin alone.\n"
+          "deprecated": true,
+          "description": "Deprecated and ignored; rendering is chosen automatically. The job's `warnings` report the ignored field."
         },
         "premium_proxy": {
           "type": "boolean",
@@ -542,7 +537,7 @@
               {
                 "type": "object",
                 "title": "screenshot",
-                "description": "Capture a screenshot mid-workflow (needs camoufox or chromium); returned under `screenshots` with this step's label.",
+                "description": "Capture a screenshot mid-workflow (needs full-browser rendering); returned under `screenshots` with this step's label.",
                 "required": [
                   "screenshot"
                 ],
@@ -649,11 +644,12 @@
               "other"
             ]
           },
-          "description": "Resource classes to block while rendering. Honoured on rendered items only; unset blocks images and fonts, `none` blocks nothing, a list replaces the default. Falls back to the project default when unset."
+          "description": "Resource classes to block while rendering. Honoured on rendered items only; unset blocks nothing on full-browser rendering, `none` blocks nothing, a list blocks the classes named. Falls back to the project default when unset."
         },
         "headless": {
           "type": "boolean",
-          "description": "Honoured on rendered items (the project default for headless is NOT merged on batch)."
+          "deprecated": true,
+          "description": "Deprecated and ignored. The browser mode is chosen automatically."
         },
         "screenshot": {
           "type": "boolean",
@@ -1029,7 +1025,7 @@
         "allOf": [
           {
             "type": "object",
-            "description": "The /v1/scrape request object as accepted by batch, minus `url`. Field names, types and validation are exactly\nScrapeRequest's (enforced by a parity test); each property below references it. Every item is merged as\njob-level value, overridden by the item's value (an explicit `false` on an item wins), with the project's\ndashboard defaults underneath both. Validation happens for every item at submission.\n\nWhat the batch worker executes: each item is one fetch or one render, and the document is returned as\n`response_format` (`html` by default, `json`, `markdown` or `text`). A field is either honoured on a batch item\nor refused at submission, never accepted and skipped. Refused with 400 INVALID_PARAMETER, naming every offending\nfield, with nothing queued or charged: `actions`, `screenshot` and its options, `network_capture`, `extract`,\n`extract_preset`, `ai_extract`, `autoparse`, `links`, `session_id`, `cache`/`cache_ttl`, `original_status`,\n`allowed_status_codes`, `parse_pdf=true`, `mode=auto`, `response_format=pdf`, and a non-GET `method` with\n`js_render` or `stealth`. A value that asks for nothing (`screenshot: false`, an empty list) is accepted. A\nrefusal caused by a project default says so in `detail`. Use /v1/scrape for those fields.\n\nA batch item is priced when it is accepted, so a bot challenge never climbs it to camoufox or retries it on a\ndifferent exit the way it can a /v1/scrape request with `premium_proxy` or `proxy`.\n",
+            "description": "The /v1/scrape request object as accepted by batch, minus `url`. Field names, types and validation are exactly\nScrapeRequest's (enforced by a parity test); each property below references it. Every item is merged as\njob-level value, overridden by the item's value (an explicit `false` on an item wins), with the project's\ndashboard defaults underneath both. Validation happens for every item at submission.\n\nWhat the batch worker executes: each item is one fetch or one render, and the document is returned as\n`response_format` (`html` by default, `json`, `markdown` or `text`). A field is either honoured on a batch item\nor refused at submission, never accepted and skipped. Refused with 400 INVALID_PARAMETER, naming every offending\nfield, with nothing queued or charged: `actions`, `screenshot` and its options, `network_capture`, `extract`,\n`extract_preset`, `ai_extract`, `autoparse`, `links`, `session_id`, `cache`/`cache_ttl`, `original_status`,\n`allowed_status_codes`, `parse_pdf=true`, `mode=auto`, `response_format=pdf`, and a non-GET `method` with\n`js_render` or `stealth`. A value that asks for nothing (`screenshot: false`, an empty list) is accepted. A\nrefusal caused by a project default says so in `detail`. Use /v1/scrape for those fields.\n\nA batch item is priced when it is accepted, so a bot challenge never escalates it to stronger rendering or retries it on a\ndifferent exit the way it can a /v1/scrape request with your own `proxy`.\n",
             "properties": {
               "method": {
                 "type": "string",
@@ -1048,12 +1044,12 @@
               "js_render": {
                 "type": "boolean",
                 "default": false,
-                "description": "Render the page with the obscura browser engine. Honoured by the batch worker. Default false (or the project default)."
+                "description": "Run the page's JavaScript before capture. Honoured by the batch worker. Default false (or the project default)."
               },
               "stealth": {
                 "type": "boolean",
                 "default": false,
-                "description": "Coming soon. Render with the camoufox anti-detection engine; takes precedence over `js_render`. Honoured by the batch worker. Default false (or the project default)."
+                "description": "Coming soon. Render with full-browser rendering hardened against bot detection; takes precedence over `js_render`. Honoured by the batch worker. Default false (or the project default)."
               },
               "impersonate": {
                 "type": "boolean",
@@ -1065,17 +1061,12 @@
                 "enum": [
                   "auto"
                 ],
-                "description": "`auto` is refused on batch with 400 INVALID_PARAMETER, also when it comes from the project defaults; the batch worker does not escalate. It runs the engine that `engine`, `js_render` or `stealth` selects."
+                "description": "`auto` is refused on batch with 400 INVALID_PARAMETER, also when it comes from the project defaults; the batch worker does not escalate. It runs the rendering that `js_render` or `stealth` selects."
               },
               "engine": {
                 "type": "string",
-                "enum": [
-                  "fetch",
-                  "obscura",
-                  "camoufox",
-                  "chromium"
-                ],
-                "description": "Engine `camoufox` is coming soon.\nEngine pin. On batch only `fetch`, `obscura`, `camoufox` are allowed; `chromium` is rejected with 400\nINVALID_PARAMETER (use /v1/scrape for chromium). Also 400 INCOMPATIBLE_FLAGS for: `mode=auto` plus any pin;\n`stealth=true` with a pin other than camoufox; `js_render=true` with `fetch`; `screenshot=true` with `fetch`\nor `obscura`. A pin the plan does not include is 403 (plans whose entitlements cannot be read allow only\nfetch and obscura). To be sure the worker renders, set `js_render` (obscura) or `stealth` (camoufox) rather\nthan relying on the pin alone.\n"
+                "deprecated": true,
+                "description": "Deprecated and ignored; rendering is chosen automatically. The job's `warnings` report the ignored field."
               },
               "premium_proxy": {
                 "type": "boolean",
@@ -1565,7 +1556,7 @@
                     {
                       "type": "object",
                       "title": "screenshot",
-                      "description": "Capture a screenshot mid-workflow (needs camoufox or chromium); returned under `screenshots` with this step's label.",
+                      "description": "Capture a screenshot mid-workflow (needs full-browser rendering); returned under `screenshots` with this step's label.",
                       "required": [
                         "screenshot"
                       ],
@@ -1672,11 +1663,12 @@
                     "other"
                   ]
                 },
-                "description": "Resource classes to block while rendering. Honoured on rendered items only; unset blocks images and fonts, `none` blocks nothing, a list replaces the default. Falls back to the project default when unset."
+                "description": "Resource classes to block while rendering. Honoured on rendered items only; unset blocks nothing on full-browser rendering, `none` blocks nothing, a list blocks the classes named. Falls back to the project default when unset."
               },
               "headless": {
                 "type": "boolean",
-                "description": "Honoured on rendered items (the project default for headless is NOT merged on batch)."
+                "deprecated": true,
+                "description": "Deprecated and ignored. The browser mode is chosen automatically."
               },
               "screenshot": {
                 "type": "boolean",
diff --git a/internal/schema/scrape.json b/internal/schema/scrape.json
index 47af860..16974ce 100644
--- a/internal/schema/scrape.json
+++ b/internal/schema/scrape.json
@@ -32,48 +32,43 @@
     "js_render": {
       "type": "boolean",
       "default": false,
-      "description": "Render in a browser engine (obscura; 3 credits datacenter, 25 residential) so JavaScript runs. Required by every browser-only flag unless stealth or mode=auto is set; cannot be combined with mode=auto. If omitted, the project's stored default applies."
+      "description": "Run the page's JavaScript before capture (3 credits on datacenter or your own proxy; 25 on managed residential exits, coming soon). Required by every browser-only flag unless stealth or mode=auto is set; cannot be combined with mode=auto. If omitted, the project's stored default applies."
     },
     "stealth": {
       "type": "boolean",
       "default": false,
-      "description": "Coming soon. Render in the hardened camoufox browser, flat 25 credits at any proxy tier; wins over js_render when both are set. Cannot be combined with mode=auto or with an engine pin other than camoufox; returns 503 ERR::ENGINE::UNAVAILABLE where camoufox is not deployed. If omitted, the project's stored default applies."
+      "description": "Coming soon. Render with full-browser rendering hardened against bot detection, flat 25 credits at any proxy tier; wins over js_render when both are set. Cannot be combined with mode=auto; returns 503 ERR::ENGINE::UNAVAILABLE where it is not available. If omitted, the project's stored default applies."
     },
     "impersonate": {
       "type": "boolean",
       "default": true,
-      "description": "Fetch tier only: present a current Chrome TLS/HTTP2 fingerprint, with matching browser headers and Accept-Encoding, to pass passive fingerprint checks. On by default, free, no JavaScript; `false` turns it off and the fetch uses a non-browser TLS handshake. Ignored on render engines. If omitted, the project's stored default applies, and `true` when the project sets none."
+      "description": "Fetch tier only: present a current browser TLS/HTTP2 fingerprint, with matching browser headers and Accept-Encoding, to pass passive fingerprint checks. On by default, free, no JavaScript; `false` turns it off and the fetch uses a non-browser TLS handshake. Ignored on rendered requests. If omitted, the project's stored default applies, and `true` when the project sets none."
     },
     "mode": {
       "type": "string",
       "enum": [
         "auto"
       ],
-      "description": "`auto` escalates through the available engines (fetch -> obscura) until a rung returns a usable page, billing only the rung that succeeded (0 if all fail) while reserving the dearest rung against quota. Incompatible with js_render, stealth and engine. If omitted, the project's stored default applies."
+      "description": "`auto` escalates through the rendering tiers (plain fetch, then JavaScript rendering) until one returns a usable page, billing only the rung that succeeded (0 if all fail) while reserving the dearest rung against quota. Incompatible with js_render and stealth. If omitted, the project's stored default applies."
     },
     "engine": {
       "type": "string",
-      "enum": [
-        "fetch",
-        "obscura",
-        "camoufox",
-        "chromium"
-      ],
-      "description": "Engine `camoufox` is coming soon. Pin the execution engine (case-insensitive); disables escalation and is never substituted. chromium (8 credits datacenter, 32 residential) is the only engine supporting headless=false; screenshots and pdf need camoufox or chromium. An unentitled engine is 403 ERR::AUTH::ENGINE_NOT_ENTITLED, an undeployed one 503 ERR::ENGINE::UNAVAILABLE, both at 0 credits. If omitted, the project's stored default applies."
+      "deprecated": true,
+      "description": "Deprecated and ignored; rendering is chosen automatically from the request's flags and the page, and you are billed for the rendering tier actually used (`X-Engine`). Accepted so existing clients keep working. The response carries `X-Warning: ENGINE_IGNORED`."
     },
     "premium_proxy": {
       "type": "boolean",
       "default": false,
-      "description": "Coming soon. Use residential exits from the managed pool: fetch 10, obscura 25, chromium 32 credits (camoufox stays 25). If no residential exit is available the request fails 503 ERR::PROXY::EXHAUSTED rather than falling back; ignored (with X-Warning PROXY_FLAG_IGNORED) when `proxy` is set. A bot challenge from a named vendor is retried on a different exit (fetch tier), then climbs to camoufox; see \"Bot challenges\" in the operation description. If omitted, the project's stored default applies."
+      "description": "Coming soon; not available yet, so bring your own `proxy` (residential works best). Will use residential exits from the managed pool: 10 credits for a plain fetch, 25 with JavaScript rendering, 32 with full-browser rendering (stealth stays 25). If no residential exit is available the request fails 503 ERR::PROXY::EXHAUSTED rather than falling back; ignored (with X-Warning PROXY_FLAG_IGNORED) when `proxy` is set. See \"Bot challenges\" in the operation description. If omitted, the project's stored default applies."
     },
     "proxy_country": {
       "type": "string",
       "pattern": "^[A-Za-z]{2}$",
-      "description": "Coming soon. ISO 3166-1 alpha-2 exit country (case-insensitive), within the residential pool. Requires premium_proxy=true (400 ERR::REQUEST::INCOMPATIBLE_FLAGS otherwise) unless `proxy` is set, in which case it is ignored with a warning; an unavailable country is 503 ERR::PROXY::EXHAUSTED, never substituted. A browser render takes its timezone and locale from this country or, when it is omitted, from the country of the pool exit it was assigned. If omitted, the project's stored default applies."
+      "description": "Coming soon. ISO 3166-1 alpha-2 exit country (case-insensitive), within the residential pool. Requires premium_proxy=true (400 ERR::REQUEST::INCOMPATIBLE_FLAGS otherwise) unless `proxy` is set, in which case it is kept as the render environment hint (browser timezone and locale follow it) while the custom URL stays the exit; an unavailable country is 503 ERR::PROXY::EXHAUSTED, never substituted. A browser render takes its timezone and locale from this country or, when it is omitted, from the country of the pool exit it was assigned. If omitted, the project's stored default applies."
     },
     "proxy": {
       "type": "string",
-      "description": "Your own proxy URL (http, https, socks5 or socks5h; credentials in userinfo). Takes precedence over premium_proxy/proxy_country and adds 0 proxy credits; loopback hosts are refused with 400 ERR::SECURITY::SSRF_BLOCKED. An unreachable proxy fails 502 ERR::PROXY::UNREACHABLE. A bot challenge from a named vendor climbs to camoufox when the proxy is http://; see \"Bot challenges\" in the operation description."
+      "description": "Your own proxy URL (http, https, socks5 or socks5h; credentials in userinfo). Takes precedence over premium_proxy and adds 0 proxy credits; proxy_country is kept as the render environment hint; loopback hosts are refused with 400 ERR::SECURITY::SSRF_BLOCKED. An unreachable proxy fails 502 ERR::PROXY::UNREACHABLE. A bot challenge from a named vendor is escalated automatically to stronger rendering on the same exit when the proxy is http:// (residential works best); see \"Bot challenges\" in the operation description."
     },
     "proxy_verify": {
       "type": "boolean",
@@ -82,7 +77,7 @@
     },
     "session_id": {
       "type": "string",
-      "description": "Reuse a session's cookies and storage (created via /v1/sessions); the session's engine is used and pinning a different engine is 400 ERR::REQUEST::INCOMPATIBLE_FLAGS. Checked before any work, at 0 credits and not retryable - an unknown, malformed or other organization's id is 404 ERR::SESSION::NOT_FOUND, a released session 410 ERR::SESSION::RELEASED, an expired one 410 ERR::SESSION::EXPIRED. A successful request increments the session's `usage_count`, sets `last_used_at` and slides `expires_at`. Requests with a session are never cached."
+      "description": "Reuse a session's cookies and storage (created via /v1/sessions); the request runs with the session's own rendering. Checked before any work, at 0 credits and not retryable - an unknown, malformed or other organization's id is 404 ERR::SESSION::NOT_FOUND, a released session 410 ERR::SESSION::RELEASED, an expired one 410 ERR::SESSION::EXPIRED. A successful request increments the session's `usage_count`, sets `last_used_at` and slides `expires_at`. Requests with a session are never cached."
     },
     "sticky_key": {
       "type": "string",
@@ -93,7 +88,7 @@
       "minimum": 0,
       "maximum": 30000,
       "default": 0,
-      "description": "Milliseconds to wait after load before capture. Browser-only: needs js_render, stealth, an engine pin with a browser, or mode=auto, else 400 ERR::REQUEST::INCOMPATIBLE_FLAGS."
+      "description": "Milliseconds to wait after load before capture. Browser-only: needs js_render, stealth, or mode=auto, else 400 ERR::REQUEST::INCOMPATIBLE_FLAGS."
     },
     "wait_for": {
       "type": "string",
@@ -549,7 +544,7 @@
           {
             "type": "object",
             "title": "screenshot",
-            "description": "Capture a screenshot mid-workflow (needs camoufox or chromium); returned under `screenshots` with this step's label.",
+            "description": "Capture a screenshot mid-workflow (needs full-browser rendering); returned under `screenshots` with this step's label.",
             "required": [
               "screenshot"
             ],
@@ -627,7 +622,7 @@
           }
         ]
       },
-      "description": "Ordered browser workflow (click, fill, scroll, ...), validated before anything is spent. Browser-only; disables the default image/font blocking and makes the request uncacheable. A failed step ends the request at 0 credits unless that step has on_error=skip."
+      "description": "Ordered browser workflow (click, fill, scroll, ...), validated before anything is spent. Browser-only and makes the request uncacheable. A failed step ends the request at 0 credits unless that step has on_error=skip."
     },
     "block_resources": {
       "type": "array",
@@ -656,16 +651,17 @@
           "other"
         ]
       },
-      "description": "Subresource classes the browser must not load (plural and short aliases accepted, case-insensitive). If omitted, renders block image+font except for screenshot, pdf, actions, or a network_capture of images/fonts; an explicit list replaces that default and `none` (alone) blocks nothing. Any value other than `none` is browser-only. If omitted, the project's stored default applies."
+      "description": "Subresource classes the browser must not load (plural and short aliases accepted, case-insensitive). If omitted, full-browser rendering blocks nothing, so images and fonts load, including for screenshot, pdf, actions and anti-bot escalation. A list blocks exactly the classes named and `none` (alone) blocks nothing. Any value other than `none` is browser-only. If omitted, the project's stored default applies."
     },
     "headless": {
       "type": "boolean",
-      "description": "false runs the browser on a real display (1920x1080 screen instead of 800x600); only engine=chromium supports it, anything else is 400 ERR::REQUEST::CAPABILITY_UNSUPPORTED at 0 credits. Either value requires a browser engine; omit to use the deployment default (headless). Headful renders skip the warm pool and add ~1s. If omitted, the project's stored default applies."
+      "deprecated": true,
+      "description": "Deprecated and ignored. Rendering is chosen automatically. Accepted so existing clients keep working. The response carries `X-Warning: ENGINE_IGNORED`."
     },
     "screenshot": {
       "type": "boolean",
       "default": false,
-      "description": "Capture a screenshot; forces the JSON envelope (image base64 under `screenshots`). Needs a rasterising engine (camoufox or chromium) - otherwise 400 ERR::REQUEST::CAPABILITY_UNSUPPORTED at 0 credits. mode=auto cannot satisfy it (its fetch rung has no rasteriser). If the image is not delivered the page is still returned but charged 0."
+      "description": "Capture a screenshot; forces the JSON envelope (image base64 under `screenshots`). Rendered with full-browser rendering - on a deployment without it, 400 ERR::REQUEST::CAPABILITY_UNSUPPORTED at 0 credits. mode=auto cannot satisfy it (its fetch rung has no rasteriser). If the image is not delivered the page is still returned but charged 0."
     },
     "screenshot_fullpage": {
       "type": "boolean",
@@ -975,7 +971,7 @@
         "pdf"
       ],
       "default": "html",
-      "description": "Body shape: html/markdown/text return the document itself, json the envelope, pdf a browser-printed PDF (needs camoufox or chromium). extract, autoparse, links, ai_extract, network_capture or screenshot override this to the JSON envelope with X-Warning FORMAT_COERCED. A non-HTML target (image, binary) requested as markdown/text fails 502 ERR::EXTRACT::FAILED at 0 credits. If omitted, the project's stored default applies."
+      "description": "Body shape: html/markdown/text return the document itself, json the envelope, pdf a PDF printed by a real browser (needs full-browser rendering). extract, autoparse, links, ai_extract, network_capture or screenshot override this to the JSON envelope with X-Warning FORMAT_COERCED. A non-HTML target (image, binary) requested as markdown/text fails 502 ERR::EXTRACT::FAILED at 0 credits. If omitted, the project's stored default applies."
     },
     "cache": {
       "type": "boolean",
diff --git a/internal/schema/session.json b/internal/schema/session.json
index b544482..7fcd896 100644
--- a/internal/schema/session.json
+++ b/internal/schema/session.json
@@ -12,14 +12,13 @@
           "type": "string",
           "enum": [
             "fetch",
-            "obscura",
-            "chromium",
-            "camoufox"
+            "js",
+            "browser"
           ],
-          "description": "Engine a session is pinned to for its whole life. Scrapes on the session run on this engine; `fingerprint` is only valid with `camoufox`."
+          "description": "The rendering tier a session is bound to for its lifetime (`fetch` is HTTP only, `js` is JavaScript rendering, `browser` is full-browser rendering). Chosen automatically when the session is created unless the create names one."
         }
       ],
-      "description": "Engine `camoufox` is coming soon. Engine to pin. Case-insensitive. Omitted means the first of `obscura`, `chromium` that this deployment runs, else `fetch`. Choose explicitly if you need a browser-only feature such as localStorage."
+      "description": "Optional. The rendering tier to bind the session to (`fetch`, `js` or `browser`); omit it and one is chosen for you. A tier the deployment does not offer is 503 `ERR::ENGINE::UNAVAILABLE`."
     },
     "ttl_seconds": {
       "type": "integer",
@@ -59,7 +58,7 @@
         "object",
         "null"
       ],
-      "description": "Camoufox fingerprint pin, stored verbatim. A non-empty object with any engine other than `camoufox` is refused with 400. `null` and `{}` count as absent."
+      "description": "Browser fingerprint pin, stored verbatim. Advanced option; a non-empty object is refused with 400 where the session's rendering cannot apply it. `null` and `{}` count as absent."
     },
     "domain_scores": {
       "type": "object",
diff --git a/openapi.yaml b/openapi.yaml
index 8b97c4d..a252f96 100644
--- a/openapi.yaml
+++ b/openapi.yaml
@@ -5,8 +5,8 @@ info:
   summary: Turn any URL into clean content or structured data with one request.
   description: |
     Spicrawl retrieves, renders and extracts web pages. One request shape serves every
-    capability; you say what you want with flags and the platform chooses the engine,
-    the proxy exit and the retries.
+    capability; you say what you want with flags and the platform chooses the rendering
+    path, the proxy exit and the retries.
 
     Rules an agent should hold on to:
 
@@ -44,7 +44,7 @@ tags:
 - name: Sessions
   description: Reuse cookies, storage and an exit IP across requests.
 - name: Browser
-  description: Drive a hosted browser over the Chrome DevTools Protocol.
+  description: Drive a hosted browser over a DevTools Protocol (CDP) WebSocket.
 - name: Requests
   description: Inspect the history of requests made in this key's project, or with the `read` scope in
     every project of its organization.
@@ -72,7 +72,7 @@ components:
       name: apikey
       description: |
         The key as a query parameter. Only for clients that cannot set headers, such as
-        a WebSocket upgrade from Puppeteer or Playwright. Prefer `bearerAuth` everywhere
+        a WebSocket upgrade from a browser-automation library. Prefer `bearerAuth` everywhere
         else, because URLs end up in logs.
   headers:
     Retry-After:
@@ -85,15 +85,15 @@ components:
       schema:
         type: string
     X-RateLimit-Limit:
-      description: Requests allowed in the current window.
+      description: Size of the key's rate-limit bucket, the most requests that can be sent back to back.
       schema:
         type: integer
     X-RateLimit-Remaining:
-      description: Requests left in the current window.
+      description: Requests left in that bucket. Never above `X-RateLimit-Limit`.
       schema:
         type: integer
     X-RateLimit-Reset:
-      description: Seconds until the window resets.
+      description: Seconds until the bucket has one request available again. Only sent when the limiter imposed a wait.
       schema:
         type: integer
   schemas:
@@ -223,7 +223,7 @@ components:
         ERR::REQUEST::CAPABILITY_UNSUPPORTED:
           status: 400
           retryable: false
-          title: The chosen engine cannot do what the request asks
+          title: The request needs a capability that is not available
         ERR::SECURITY::SSRF_BLOCKED:
           status: 400
           retryable: false
@@ -315,7 +315,7 @@ components:
         ERR::PROXY::AUTH_FAILED:
           status: 502
           retryable: false
-          title: Proxy rejected our credentials
+          title: Proxy rejected the credentials
         ERR::PROXY::RATE_LIMITED:
           status: 502
           retryable: true
@@ -449,7 +449,11 @@ components:
                 description: Attempt number, from 1.
               engine:
                 type: string
-                description: Engine this attempt ran on.
+                enum:
+                - fetch
+                - js
+                - browser
+                description: Rendering tier this attempt used (`fetch`, `js` for JavaScript rendering, `browser` for full-browser rendering).
               proxy:
                 type: string
                 description: Redacted exit label or proxy scheme and host. Never contains credentials.
@@ -470,7 +474,11 @@ components:
           description: Time actually spent, in milliseconds.
         engine:
           type: string
-          description: Engine that served the final attempt.
+          enum:
+          - fetch
+          - js
+          - browser
+          description: Rendering tier that served the final attempt.
         proxy:
           type: object
           description: Redacted description of the exit used.
@@ -521,68 +529,61 @@ components:
         js_render:
           type: boolean
           default: false
-          description: Render in a browser engine (obscura; 3 credits datacenter, 25 residential) so JavaScript
-            runs. Required by every browser-only flag unless stealth or mode=auto is set; cannot be combined
+          description: Run the page's JavaScript before capture (3 credits on datacenter or your own proxy; 25 on managed
+            residential exits, coming soon). Required by every browser-only flag unless stealth or mode=auto is set; cannot be combined
             with mode=auto. If omitted, the project's stored default applies.
         stealth:
           type: boolean
           default: false
-          description: Coming soon. Render in the hardened camoufox browser, flat 25 credits at any proxy tier; wins
-            over js_render when both are set. Cannot be combined with mode=auto or with an engine pin
-            other than camoufox; returns 503 ERR::ENGINE::UNAVAILABLE where camoufox is not deployed.
+          description: Coming soon. Render with full-browser rendering hardened against bot detection, flat 25 credits at any
+            proxy tier; wins over js_render when both are set. Cannot be combined with mode=auto; returns
+            503 ERR::ENGINE::UNAVAILABLE where it is not available.
             If omitted, the project's stored default applies.
         impersonate:
           type: boolean
           default: true
-          description: 'Fetch tier only: present a current Chrome TLS/HTTP2 fingerprint, with matching
+          description: 'Fetch tier only: present a current browser TLS/HTTP2 fingerprint, with matching
             browser headers and Accept-Encoding, to pass passive fingerprint checks. On by default, free,
             no JavaScript; `false` turns it off and the fetch uses a non-browser TLS handshake. Ignored
-            on render engines. If omitted, the project''s stored default applies, and `true` when the project sets
+            on rendered requests. If omitted, the project''s stored default applies, and `true` when the project sets
             none.'
         mode:
           type: string
           enum:
           - auto
-          description: '`auto` escalates through the available engines (fetch -> obscura) until a rung returns a usable page,
+          description: '`auto` escalates through the rendering tiers (plain fetch, then JavaScript rendering) until one returns a usable page,
             billing only the rung that succeeded (0 if all fail) while reserving the dearest rung against
-            quota. Incompatible with js_render, stealth and engine. If omitted, the project''s stored
+            quota. Incompatible with js_render and stealth. If omitted, the project''s stored
             default applies.'
         engine:
           type: string
-          enum:
-          - fetch
-          - obscura
-          - camoufox
-          - chromium
-          description: Engine `camoufox` is coming soon. Pin the execution engine (case-insensitive); disables escalation and is never substituted.
-            chromium (8 credits datacenter, 32 residential) is the only engine supporting headless=false;
-            screenshots and pdf need camoufox or chromium. An unentitled engine is 403 ERR::AUTH::ENGINE_NOT_ENTITLED,
-            an undeployed one 503 ERR::ENGINE::UNAVAILABLE, both at 0 credits. If omitted, the project's
-            stored default applies.
+          deprecated: true
+          description: 'Deprecated and ignored; rendering is chosen automatically from the request''s flags and the page, and you are billed for the rendering tier actually used (`X-Engine`). Accepted so existing clients keep working. The response carries `X-Warning: ENGINE_IGNORED`.'
         premium_proxy:
           type: boolean
           default: false
-          description: 'Coming soon. Use residential exits from the managed pool: fetch 10, obscura 25, chromium 32
-            credits (camoufox stays 25). If no residential exit is available the request fails 503 ERR::PROXY::EXHAUSTED
+          description: 'Coming soon; not available yet, so bring your own `proxy` (residential works best). Will use residential exits from the
+            managed pool: 10 credits for a plain fetch, 25 with JavaScript rendering, 32 with full-browser rendering
+            (stealth stays 25). If no residential exit is available the request fails 503 ERR::PROXY::EXHAUSTED
             rather than falling back; ignored (with X-Warning PROXY_FLAG_IGNORED) when `proxy` is set.
-            A bot challenge from a named vendor is retried on a different exit (fetch tier), then climbs
-            to camoufox; see "Bot challenges" in the operation description. If omitted, the project''s stored default
+            See "Bot challenges" in the operation description. If omitted, the project''s stored default
             applies.'
         proxy_country:
           type: string
           pattern: ^[A-Za-z]{2}$
           description: Coming soon. ISO 3166-1 alpha-2 exit country (case-insensitive), within the residential pool.
             Requires premium_proxy=true (400 ERR::REQUEST::INCOMPATIBLE_FLAGS otherwise) unless `proxy`
-            is set, in which case it is ignored with a warning; an unavailable country is 503 ERR::PROXY::EXHAUSTED,
+            is set, in which case it is kept as the render environment hint (browser timezone and
+            locale follow it) while the custom URL stays the exit; an unavailable country is 503 ERR::PROXY::EXHAUSTED,
             never substituted. A browser render takes its timezone and locale from this country or, when
             it is omitted, from the country of the pool exit it was assigned. If omitted, the project's
             stored default applies.
         proxy:
           type: string
           description: Your own proxy URL (http, https, socks5 or socks5h; credentials in userinfo). Takes
-            precedence over premium_proxy/proxy_country and adds 0 proxy credits; loopback hosts are refused
+            precedence over premium_proxy and adds 0 proxy credits; proxy_country is kept as the render environment hint; loopback hosts are refused
             with 400 ERR::SECURITY::SSRF_BLOCKED. An unreachable proxy fails 502 ERR::PROXY::UNREACHABLE.
-            A bot challenge from a named vendor climbs to camoufox when the proxy is http://; see "Bot
+            A bot challenge from a named vendor is escalated automatically to stronger rendering on the same exit when the proxy is http:// (residential works best); see "Bot
             challenges" in the operation description.
         proxy_verify:
           type: boolean
@@ -591,8 +592,8 @@ components:
             fast. Requires `proxy` (400 ERR::REQUEST::INCOMPATIBLE_FLAGS otherwise).
         session_id:
           type: string
-          description: Reuse a session's cookies and storage (created via /v1/sessions); the session's
-            engine is used and pinning a different engine is 400 ERR::REQUEST::INCOMPATIBLE_FLAGS. Checked
+          description: Reuse a session's cookies and storage (created via /v1/sessions); the request runs
+            with the session's own rendering. Checked
             before any work, at 0 credits and not retryable - an unknown, malformed or other organization's
             id is 404 ERR::SESSION::NOT_FOUND, a released session 410 ERR::SESSION::RELEASED, an expired one
             410 ERR::SESSION::EXPIRED. A successful request increments the session's `usage_count`, sets
@@ -608,7 +609,7 @@ components:
           maximum: 30000
           default: 0
           description: 'Milliseconds to wait after load before capture. Browser-only: needs js_render,
-            stealth, an engine pin with a browser, or mode=auto, else 400 ERR::REQUEST::INCOMPATIBLE_FLAGS.'
+            stealth, or mode=auto, else 400 ERR::REQUEST::INCOMPATIBLE_FLAGS.'
         wait_for:
           type: string
           description: CSS selector to wait for before capture. Browser-only. If it never appears the
@@ -627,7 +628,7 @@ components:
           items:
             $ref: '#/components/schemas/ScrapeAction'
           description: Ordered browser workflow (click, fill, scroll, ...), validated before anything
-            is spent. Browser-only; disables the default image/font blocking and makes the request uncacheable.
+            is spent. Browser-only and makes the request uncacheable.
             A failed step ends the request at 0 credits unless that step has on_error=skip.
         block_resources:
           type: array
@@ -655,21 +656,19 @@ components:
             - websockets
             - other
           description: Subresource classes the browser must not load (plural and short aliases accepted,
-            case-insensitive). If omitted, renders block image+font except for screenshot, pdf, actions,
-            or a network_capture of images/fonts; an explicit list replaces that default and `none` (alone)
-            blocks nothing. Any value other than `none` is browser-only. If omitted, the project's stored
-            default applies.
+            case-insensitive). If omitted, full-browser rendering blocks nothing, so images and fonts load,
+            including for screenshot, pdf, actions and anti-bot escalation. A list blocks exactly the
+            classes named and `none` (alone) blocks nothing. Any value other than `none` is browser-only.
+            If omitted, the project's stored default applies.
         headless:
           type: boolean
-          description: false runs the browser on a real display (1920x1080 screen instead of 800x600);
-            only engine=chromium supports it, anything else is 400 ERR::REQUEST::CAPABILITY_UNSUPPORTED
-            at 0 credits. Either value requires a browser engine; omit to use the deployment default (headless).
-            Headful renders skip the warm pool and add ~1s. If omitted, the project's stored default applies.
+          deprecated: true
+          description: 'Deprecated and ignored. Rendering is chosen automatically. Accepted so existing clients keep working. The response carries `X-Warning: ENGINE_IGNORED`.'
         screenshot:
           type: boolean
           default: false
           description: Capture a screenshot; forces the JSON envelope (image base64 under `screenshots`).
-            Needs a rasterising engine (camoufox or chromium) - otherwise 400 ERR::REQUEST::CAPABILITY_UNSUPPORTED
+            Rendered with full-browser rendering - on a deployment without it, 400 ERR::REQUEST::CAPABILITY_UNSUPPORTED
             at 0 credits. mode=auto cannot satisfy it (its fetch rung has no rasteriser). If the image
             is not delivered the page is still returned but charged 0.
         screenshot_fullpage:
@@ -772,7 +771,7 @@ components:
           - pdf
           default: html
           description: 'Body shape: html/markdown/text return the document itself, json the envelope,
-            pdf a browser-printed PDF (needs camoufox or chromium). extract, autoparse, links, ai_extract,
+            pdf a PDF printed by a real browser (needs full-browser rendering). extract, autoparse, links, ai_extract,
             network_capture or screenshot override this to the JSON envelope with X-Warning FORMAT_COERCED.
             A non-HTML target (image, binary) requested as markdown/text fails 502 ERR::EXTRACT::FAILED
             at 0 credits. If omitted, the project''s stored default applies.'
@@ -1159,7 +1158,7 @@ components:
     ScrapeActionScreenshot:
       type: object
       title: screenshot
-      description: Capture a screenshot mid-workflow (needs camoufox or chromium); returned under `screenshots`
+      description: Capture a screenshot mid-workflow (needs full-browser rendering); returned under `screenshots`
         with this step's label.
       required:
       - screenshot
@@ -1503,6 +1502,10 @@ components:
                 type: integer
               engine:
                 type: string
+                enum:
+                - fetch
+                - js
+                - browser
               proxy:
                 type: string
               outcome:
@@ -1517,6 +1520,10 @@ components:
           type: integer
         engine:
           type: string
+          enum:
+          - fetch
+          - js
+          - browser
         proxy:
           type: object
           properties:
@@ -1538,7 +1545,6 @@ components:
       - headers
       - truncated
       - credits
-      - engine
       - proxy_source
       - warnings
       description: Returned for response_format=json, or whenever extract/autoparse/links/ai_extract/network_capture/screenshot
@@ -1576,10 +1582,10 @@ components:
           type: string
           enum:
           - fetch
-          - obscura
-          - camoufox
-          - chromium
-          description: Engine that produced the page.
+          - js
+          - browser
+          description: The rendering tier used to produce the page. `fetch` is HTTP only, `js` is JavaScript
+            rendering, `browser` is full-browser rendering.
         proxy_source:
           type: string
           enum:
@@ -1657,8 +1663,8 @@ components:
         `js_render` or `stealth`. A value that asks for nothing (`screenshot: false`, an empty list) is accepted. A
         refusal caused by a project default says so in `detail`. Use /v1/scrape for those fields.
 
-        A batch item is priced when it is accepted, so a bot challenge never climbs it to camoufox or retries it on a
-        different exit the way it can a /v1/scrape request with `premium_proxy` or `proxy`.
+        A batch item is priced when it is accepted, so a bot challenge never escalates it to stronger rendering or retries it on a
+        different exit the way it can a /v1/scrape request with your own `proxy`.
       properties:
         method:
           $ref: '#/components/schemas/ScrapeRequest/properties/method'
@@ -1667,11 +1673,11 @@ components:
             400, because a browser navigation is always a GET.
         js_render:
           $ref: '#/components/schemas/ScrapeRequest/properties/js_render'
-          description: Render the page with the obscura browser engine. Honoured by the batch worker.
+          description: Run the page's JavaScript before capture. Honoured by the batch worker.
             Default false (or the project default).
         stealth:
           $ref: '#/components/schemas/ScrapeRequest/properties/stealth'
-          description: Coming soon. Render with the camoufox anti-detection engine; takes precedence over `js_render`.
+          description: Coming soon. Render with full-browser rendering hardened against bot detection; takes precedence over `js_render`.
             Honoured by the batch worker. Default false (or the project default).
         impersonate:
           $ref: '#/components/schemas/ScrapeRequest/properties/impersonate'
@@ -1681,18 +1687,12 @@ components:
           $ref: '#/components/schemas/ScrapeRequest/properties/mode'
           description: >-
             `auto` is refused on batch with 400 INVALID_PARAMETER, also when it comes from the project
-            defaults; the batch worker does not escalate. It runs the engine that `engine`, `js_render` or
+            defaults; the batch worker does not escalate. It runs the rendering that `js_render` or
             `stealth` selects.
         engine:
           $ref: '#/components/schemas/ScrapeRequest/properties/engine'
-          description: |
-            Engine `camoufox` is coming soon.
-            Engine pin. On batch only `fetch`, `obscura`, `camoufox` are allowed; `chromium` is rejected with 400
-            INVALID_PARAMETER (use /v1/scrape for chromium). Also 400 INCOMPATIBLE_FLAGS for: `mode=auto` plus any pin;
-            `stealth=true` with a pin other than camoufox; `js_render=true` with `fetch`; `screenshot=true` with `fetch`
-            or `obscura`. A pin the plan does not include is 403 (plans whose entitlements cannot be read allow only
-            fetch and obscura). To be sure the worker renders, set `js_render` (obscura) or `stealth` (camoufox) rather
-            than relying on the pin alone.
+          deprecated: true
+          description: Deprecated and ignored; rendering is chosen automatically. The job's `warnings` report the ignored field.
         premium_proxy:
           $ref: '#/components/schemas/ScrapeRequest/properties/premium_proxy'
           description: Coming soon. Use the residential proxy pool instead of datacenter. Honoured by the batch worker;
@@ -1737,12 +1737,12 @@ components:
         block_resources:
           $ref: '#/components/schemas/ScrapeRequest/properties/block_resources'
           description: Resource classes to block while rendering. Honoured on rendered items only; unset
-            blocks images and fonts, `none` blocks nothing, a list replaces the default. Falls back to
+            blocks nothing on full-browser rendering, `none` blocks nothing, a list blocks the classes named. Falls back to
             the project default when unset.
         headless:
           $ref: '#/components/schemas/ScrapeRequest/properties/headless'
-          description: >-
-            Honoured on rendered items (the project default for headless is NOT merged on batch).
+          deprecated: true
+          description: Deprecated and ignored. The browser mode is chosen automatically.
         screenshot:
           $ref: '#/components/schemas/ScrapeRequest/properties/screenshot'
           description: >-
@@ -2271,16 +2271,16 @@ components:
       properties:
         content:
           type: string
-          description: The worker's stored `result` value as raw JSON text (a JSON string literal
-            holding the document in the item's `response_format`, so JSON-decode it once to get the html,
-            markdown or text). May be a byte prefix when
-            `truncated`, in which case it is not valid JSON.
+          description: The document as plain text, in the item's `response_format` (the HTML, markdown or
+            text itself). It is the line's ordinary JSON string, already decoded by your JSON parser once, so
+            do not decode it again. For `response_format` `json` it is the JSON document as a string (the body
+            as retrieved), which you parse to get the object. May be a byte prefix when `truncated`.
         bytes:
           type: integer
           format: int64
           minimum: 0
-          description: Full size of the stored payload in bytes, before any truncation. Compare with the
-            length of `content`. 0 when `unavailable`.
+          description: Full size of the payload in bytes, before any truncation; equal to the length of `content`
+            unless `truncated`. 0 when `unavailable`.
         truncated:
           type: boolean
           description: 'True when `content` is only a prefix: the payload exceeded 512 KiB, or the page''s
@@ -2349,6 +2349,12 @@ components:
           format: int64
           minimum: 0
           description: Wall-clock time spent on the item's final attempt, in ms. 0 when not recorded.
+        warnings:
+          type: array
+          items:
+            type: string
+          description: Warning codes for this item, e.g. `EMPTY_RENDER` (the page rendered empty, so the
+            item was charged 0 credits). Omitted when there are none.
         result_ref:
           type: string
           description: Storage pointer for a per-item payload. Currently never populated (the worker writes
@@ -2389,11 +2395,11 @@ components:
       type: string
       enum:
       - fetch
-      - obscura
-      - chromium
-      - camoufox
-      description: Engine a session is pinned to for its whole life. Scrapes on the session run on this
-        engine; `fingerprint` is only valid with `camoufox`.
+      - js
+      - browser
+      description: The rendering tier a session is bound to for its lifetime (`fetch` is HTTP only, `js` is
+        JavaScript rendering, `browser` is full-browser rendering). Chosen automatically when the session
+        is created unless the create names one.
     SessionCreateRequest:
       type: object
       additionalProperties: false
@@ -2402,9 +2408,8 @@ components:
         engine:
           allOf:
           - $ref: '#/components/schemas/SessionEngine'
-          description: Engine `camoufox` is coming soon. Engine to pin. Case-insensitive. Omitted means the first of `obscura`, `chromium`
-            that this deployment runs, else `fetch`. Choose explicitly if you need a browser-only feature
-            such as localStorage.
+          description: Optional. The rendering tier to bind the session to (`fetch`, `js` or `browser`);
+            omit it and one is chosen for you. A tier the deployment does not offer is 503 `ERR::ENGINE::UNAVAILABLE`.
         ttl_seconds:
           type: integer
           minimum: 30
@@ -2443,8 +2448,8 @@ components:
           type:
           - object
           - 'null'
-          description: Camoufox fingerprint pin, stored verbatim. A non-empty object with any engine other
-            than `camoufox` is refused with 400. `null` and `{}` count as absent.
+          description: Browser fingerprint pin, stored verbatim. Advanced option; a non-empty object is refused with
+            400 where the session's rendering cannot apply it. `null` and `{}` count as absent.
         domain_scores:
           type: object
           description: Seed per-domain health, keyed by lowercase registrable domain (e.g. `example.com`).
@@ -2464,7 +2469,6 @@ components:
       required:
       - id
       - project_id
-      - engine
       - status
       - sticky_key
       - proxy
@@ -2549,7 +2553,7 @@ components:
             $ref: '#/components/schemas/SessionDomainScore'
         fingerprint:
           type: object
-          description: Camoufox fingerprint, as stored. Omitted when none was set.
+          description: Browser fingerprint, as stored. Omitted when none was set.
         lease:
           $ref: '#/components/schemas/SessionLease'
         warnings:
@@ -2773,7 +2777,7 @@ components:
           type:
           - object
           - 'null'
-          description: Stored Camoufox fingerprint, or null when none. Omitted only in edge cases.
+          description: Stored browser fingerprint, or null when none. Omitted only in edge cases.
         domain_scores:
           type: object
           additionalProperties:
@@ -2814,7 +2818,6 @@ components:
       - id
       - created_at
       - project_id
-      - engine
       - status
       - url
       - proxy
@@ -2838,8 +2841,8 @@ components:
           - 01M0FJZ8Q3W4B5T8J2V9K6X1RD
         engine:
           type: string
-          description: Engine that served it, e.g. `fetch`, `obscura`, `chromium`, `camoufox`. May be
-            empty for requests refused before an engine was chosen.
+          description: Rendering tier that served it (`fetch`, `js` or `browser`). Empty for requests
+            refused before a tier was chosen.
         status:
           type: string
           enum:
@@ -3017,7 +3020,7 @@ components:
     RequestLogBlock:
       type: object
       description: Present only when a bot challenge was detected. Use `vendor` to pick a countermeasure
-        (e.g. stealth engine or residential exit).
+        (e.g. stealth rendering or residential exit).
       properties:
         vendor:
           type: string
@@ -3145,12 +3148,12 @@ components:
       properties:
         key:
           type: string
-          description: 'Bucket key: a `YYYY-MM-DD` day, a project id, an engine name, or a feature (`extract`,
+          description: 'Bucket key: a `YYYY-MM-DD` day, a project id, a rendering tier (`fetch`, `js` or `browser`), or a feature (`extract`,
             `ai_extract`, `proxy_datacenter`, `proxy_residential`, `batch`). Groups are sorted by key.'
         label:
           type: string
-          description: Human label for engine groups (e.g. `Chromium`). Absent for other dimensions and
-            unknown engines.
+          description: Human label for rendering-tier groups (for example "JavaScript rendering"). Absent for
+            other dimensions and unknown tiers.
         metrics:
           $ref: '#/components/schemas/UsageMetricMap'
     UsageByKey:
@@ -3837,17 +3840,18 @@ paths:
       description: |-
         Fetch one URL synchronously and return it as html, markdown, text, a PDF, or a JSON envelope with extracted data.
 
-        Choosing an engine (cheapest first):
-        - Default (fetch, 1 credit): plain HTTP, no JavaScript, presenting a current Chrome TLS/HTTP2 fingerprint (`impersonate`, on by default and free; `impersonate=false` turns it off).
-        - `js_render=true` (obscura, 3): content is built by JavaScript, or you need wait/wait_for/actions/block_resources/network_capture.
-        - `engine=chromium` (8): needed for screenshot and response_format=pdf. `stealth=true` (camoufox) is coming soon.
-        - `mode=auto`: unsure - escalates through the available engines, bills only the rung that worked.
+        How a request is rendered (cheapest first). You do not choose: Spicrawl picks the cheapest path that can do what the request asks.
+        - Default (plain fetch, 1 credit): plain HTTP, no JavaScript, presenting a current browser TLS/HTTP2 fingerprint (`impersonate`, on by default and free; `impersonate=false` turns it off).
+        - `js_render=true` (JavaScript rendering, 3 credits): content is built by JavaScript, or you need wait/wait_for/block_resources/network_capture.
+        - Screenshots, `response_format=pdf` and `actions` use full-browser rendering (8 credits). `stealth=true` (full-browser rendering hardened against bot detection, 25 credits) is coming soon.
+        - `mode=auto`: unsure - escalates through the available rendering tiers, bills only the tier that worked.
         - Managed proxy pools (`premium_proxy`) are coming soon; during the beta pass your own proxy with `proxy`.
+        - The `engine` and `headless` fields are deprecated and ignored.
         Browser-only flags on the fetch tier are a 400, never silently ignored.
 
         Billing: failures cost 0 (errors, bot challenges, timeouts, target statuses other than 200/404/410 unless listed in allowed_status_codes, undelivered screenshots). A cache hit is billed at the same price as the fetch that stored it: the cache saves the fetch (latency and load on the target), not credits. Like any request, a hit is refused with 402 when the monthly allowance cannot cover its price. Check X-Credits-Charged.
 
-        Bot challenges: a challenge page attributed to a named vendor (Cloudflare, DataDome, PerimeterX, Akamai) is never returned as a success. A fetch through a managed pool exit that meets one is retried once on a different exit, free (GET/HEAD/OPTIONS only, not with `sticky_key` or `session_id`, never on your own `proxy`). With `premium_proxy=true` or your own `proxy`, no `engine` pin and no `mode=auto`, a request whose page is still a challenge then climbs to camoufox, which waits out or clicks through the interstitial. Only the rung that returned the page is billed (camoufox 25, or the first rung's price), and 0 if every rung was challenged (502 ERR::UPSTREAM::CHALLENGE). A transport error, a refusal with no vendor marker (such as a bare 403) or a non-billable status such as 404 does not climb. The climb is left off for a non-GET method, headless=false, response_format=pdf, a screenshot, actions, a `proxy` that is not http://, a max_cost below the camoufox price, or a deployment without camoufox; an allowance that covers the first rung but not camoufox runs the request without it. X-Engine names the engine that served, each abandoned rung adds an `X-Warning: ESCALATED`, and diagnostics.attempts lists every attempt (in the JSON envelope on a successful climb). Batch items never climb.
+        Bot challenges: a challenge page attributed to a named vendor (Cloudflare, DataDome, PerimeterX, Akamai) is never returned as a success. A fetch through a managed pool exit that meets one is retried once on a different exit, free (GET/HEAD/OPTIONS only, not with `sticky_key` or `session_id`, never on your own `proxy`). When you bring your own `proxy` (residential works best) and send no `mode=auto`, a request whose page is still a challenge is escalated automatically to stronger full-browser rendering on the same exit, which works through the interstitial and returns the real page; there is no flag to set. This is how Cloudflare-protected pages are supported. Automatic handling on managed premium exits is coming soon. Success is not guaranteed for every page. Only the tier that returned the page is billed (up to 25 credits, or the first tier's price), and 0 if every tier was challenged (502 ERR::UPSTREAM::CHALLENGE). On the default shared pool a challenged page may return that error; retry with your own residential `proxy`. A transport error, a refusal with no vendor marker (such as a bare 403) or a non-billable status such as 404 does not escalate. Escalation is skipped for a non-GET method, response_format=pdf, a screenshot, actions, a `proxy` that is not http://, or a max_cost below the escalated price; an allowance that covers the first attempt but not the escalation runs the request without it. X-Engine reports the rendering tier that served, each abandoned tier adds an `X-Warning: ESCALATED`, and diagnostics.attempts lists every attempt (in the JSON envelope on a successful escalation). Batch items never escalate.
 
         Status: the HTTP status is the platform's. A blocked or erroring site is usually still HTTP 200 - read envelope `status` or X-Target-Status for the site's answer. Errors are application/problem+json; retry only when `retryable` is true.
 
@@ -3863,24 +3867,24 @@ paths:
             datacenter: 1
             residential: 10
             mobile: 10
-          obscura:
+          js_rendering:
             direct: 3
             datacenter: 3
             residential: 25
             mobile: 25
-          camoufox:
+          stealth_rendering:
             direct: 25
             datacenter: 25
             residential: 25
             mobile: 25
-          chromium:
+          full_browser_rendering:
             direct: 8
             datacenter: 8
             residential: 32
             mobile: 32
         custom_proxy: priced as the direct column (no proxy surcharge)
         ai_extract: 4
-        ai_extract_note: added on top of the engine price; the only additive item
+        ai_extract_note: added on top of the rendering price; the only additive item
         failures: 0
         cache_hit: the price of the fetch that stored it
         billable_target_statuses:
@@ -3890,7 +3894,7 @@ paths:
         billable_target_statuses_note: plus any in allowed_status_codes; other target statuses return
           the body at 0
         mode_auto: bills only the rung that succeeded; reserves the dearest rung against the monthly allowance
-        challenge_escalation: with premium_proxy or proxy, a vendor challenge may climb to camoufox; bills
+        challenge_escalation: with your own proxy, a vendor challenge may be escalated to stronger rendering; bills
           only the rung that returned the page, 0 if every rung was challenged; batch items never climb
         impersonate: 0
         extract_autoparse_links_network_capture: 0
@@ -3924,8 +3928,8 @@ paths:
       - name: js_render
         in: query
         required: false
-        description: Render in a browser engine (obscura; 3 credits datacenter, 25 residential) so JavaScript
-          runs. Required by every browser-only flag unless stealth or mode=auto is set; cannot be combined
+        description: Run the page's JavaScript before capture (3 credits on datacenter or your own proxy; 25 on managed
+          residential exits, coming soon). Required by every browser-only flag unless stealth or mode=auto is set; cannot be combined
           with mode=auto. If omitted, the project's stored default applies. Accepts true/false/1/0; a
           bare `?js_render` means true.
         schema:
@@ -3934,9 +3938,9 @@ paths:
       - name: stealth
         in: query
         required: false
-        description: Coming soon. Render in the hardened camoufox browser, flat 25 credits at any proxy tier; wins
-          over js_render when both are set. Cannot be combined with mode=auto or with an engine pin other
-          than camoufox; returns 503 ERR::ENGINE::UNAVAILABLE where camoufox is not deployed. If omitted,
+        description: Coming soon. Render with full-browser rendering hardened against bot detection, flat 25 credits at any
+          proxy tier; wins over js_render when both are set. Cannot be combined with mode=auto; returns
+          503 ERR::ENGINE::UNAVAILABLE where it is not available. If omitted,
           the project's stored default applies. Accepts true/false/1/0; a bare `?stealth` means true.
         schema:
           type: boolean
@@ -3944,10 +3948,10 @@ paths:
       - name: impersonate
         in: query
         required: false
-        description: Fetch tier only. Present a current Chrome TLS/HTTP2 fingerprint, with matching browser
+        description: Fetch tier only. Present a current browser TLS/HTTP2 fingerprint, with matching browser
           headers and Accept-Encoding, to pass passive fingerprint checks. On by default, free, no JavaScript;
-          `impersonate=false` turns it off and the fetch uses a non-browser TLS handshake. Ignored on render
-          engines.
+          `impersonate=false` turns it off and the fetch uses a non-browser TLS handshake. Ignored on rendered
+          requests.
           If omitted, the project's stored default applies, and true when the project sets none. Accepts
           true/false/1/0; a bare `?impersonate` means true.
         schema:
@@ -3956,9 +3960,9 @@ paths:
       - name: mode
         in: query
         required: false
-        description: '`auto` escalates through the available engines (fetch -> obscura) until a rung returns a usable page,
+        description: '`auto` escalates through the rendering tiers (plain fetch, then JavaScript rendering) until one returns a usable page,
           billing only the rung that succeeded (0 if all fail) while reserving the dearest rung against
-          quota. Incompatible with js_render, stealth and engine. If omitted, the project''s stored default
+          quota. Incompatible with js_render and stealth. If omitted, the project''s stored default
           applies.'
         schema:
           type: string
@@ -3967,26 +3971,18 @@ paths:
       - name: engine
         in: query
         required: false
-        description: Engine `camoufox` is coming soon. Pin the execution engine (case-insensitive); disables escalation and is never substituted.
-          chromium (8 credits datacenter, 32 residential) is the only engine supporting headless=false;
-          screenshots and pdf need camoufox or chromium. An unentitled engine is 403 ERR::AUTH::ENGINE_NOT_ENTITLED,
-          an undeployed one 503 ERR::ENGINE::UNAVAILABLE, both at 0 credits. If omitted, the project's
-          stored default applies.
+        deprecated: true
+        description: 'Deprecated and ignored; rendering is chosen automatically from the request''s flags and the page, and you are billed for the rendering tier actually used (`X-Engine`). Accepted so existing clients keep working. The response carries `X-Warning: ENGINE_IGNORED`.'
         schema:
           type: string
-          enum:
-          - fetch
-          - obscura
-          - camoufox
-          - chromium
       - name: premium_proxy
         in: query
         required: false
-        description: 'Coming soon. Use residential exits from the managed pool: fetch 10, obscura 25, chromium 32 credits
-          (camoufox stays 25). If no residential exit is available the request fails 503 ERR::PROXY::EXHAUSTED
-          rather than falling back; ignored (with X-Warning PROXY_FLAG_IGNORED) when `proxy` is set. A
-          bot challenge from a named vendor is retried on a different exit (fetch tier), then climbs to
-          camoufox; see "Bot challenges" in the operation description. If omitted, the project''s stored default applies.
+        description: 'Coming soon; not available yet, so bring your own `proxy` (residential works best). Will use residential exits from the
+          managed pool: 10 credits for a plain fetch, 25 with JavaScript rendering, 32 with full-browser rendering
+          (stealth stays 25). If no residential exit is available the request fails 503 ERR::PROXY::EXHAUSTED
+          rather than falling back; ignored (with X-Warning PROXY_FLAG_IGNORED) when `proxy` is set.
+          See "Bot challenges" in the operation description. If omitted, the project''s stored default applies.
           Accepts true/false/1/0; a bare `?premium_proxy` means true.'
         schema:
           type: boolean
@@ -3996,7 +3992,8 @@ paths:
         required: false
         description: Coming soon. ISO 3166-1 alpha-2 exit country (case-insensitive), within the residential pool.
           Requires premium_proxy=true (400 ERR::REQUEST::INCOMPATIBLE_FLAGS otherwise) unless `proxy`
-          is set, in which case it is ignored with a warning; an unavailable country is 503 ERR::PROXY::EXHAUSTED,
+          is set, in which case it is kept as the render environment hint (browser timezone and
+          locale follow it) while the custom URL stays the exit; an unavailable country is 503 ERR::PROXY::EXHAUSTED,
           never substituted. A browser render takes its timezone and locale from this country or, when
           it is omitted, from the country of the pool exit it was assigned. If omitted, the project's
           stored default applies.
@@ -4007,9 +4004,9 @@ paths:
         in: query
         required: false
         description: Your own proxy URL (http, https, socks5 or socks5h; credentials in userinfo). Takes
-          precedence over premium_proxy/proxy_country and adds 0 proxy credits; loopback hosts are refused
+          precedence over premium_proxy and adds 0 proxy credits; proxy_country is kept as the render environment hint; loopback hosts are refused
           with 400 ERR::SECURITY::SSRF_BLOCKED. An unreachable proxy fails 502 ERR::PROXY::UNREACHABLE.
-          A bot challenge from a named vendor climbs to camoufox when the proxy is http://; see "Bot
+          A bot challenge from a named vendor is escalated automatically to stronger rendering on the same exit when the proxy is http:// (residential works best); see "Bot
           challenges" in the operation description.
         schema:
           type: string
@@ -4025,8 +4022,8 @@ paths:
       - name: session_id
         in: query
         required: false
-        description: Reuse a session's cookies and storage (created via /v1/sessions); the session's engine
-          is used and pinning a different engine is 400 ERR::REQUEST::INCOMPATIBLE_FLAGS. Checked before
+        description: Reuse a session's cookies and storage (created via /v1/sessions); the request runs
+          with the session's own rendering. Checked before
           any work, at 0 credits and not retryable - an unknown, malformed or other organization's id is
           404 ERR::SESSION::NOT_FOUND, a released session 410 ERR::SESSION::RELEASED, an expired one 410
           ERR::SESSION::EXPIRED. A successful request increments the session's `usage_count`, sets
@@ -4045,7 +4042,7 @@ paths:
         in: query
         required: false
         description: 'Milliseconds to wait after load before capture. Browser-only: needs js_render, stealth,
-          an engine pin with a browser, or mode=auto, else 400 ERR::REQUEST::INCOMPATIBLE_FLAGS.'
+          or mode=auto, else 400 ERR::REQUEST::INCOMPATIBLE_FLAGS.'
         schema:
           type: integer
           minimum: 0
@@ -4073,7 +4070,7 @@ paths:
         in: query
         required: false
         description: URL-encoded JSON array. Ordered browser workflow (click, fill, scroll, ...), validated
-          before anything is spent. Browser-only; disables the default image/font blocking and makes the
+          before anything is spent. Browser-only and makes the
           request uncacheable. A failed step ends the request at 0 credits unless that step has on_error=skip.
         schema:
           type: string
@@ -4087,9 +4084,10 @@ paths:
         in: query
         required: false
         description: Comma-separated list (blank items dropped). Subresource classes the browser must
-          not load (plural and short aliases accepted, case-insensitive). If omitted, renders block image+font
-          except for screenshot, pdf, actions, or a network_capture of images/fonts; an explicit list
-          replaces that default and `none` (alone) blocks nothing. Any value other than `none` is browser-only.
+          not load (plural and short aliases accepted, case-insensitive). If omitted, full-browser rendering
+          blocks nothing, so images and fonts load, including for screenshot, pdf, actions and anti-bot
+          escalation. A list blocks exactly the classes named and `none` (alone) blocks nothing. Any value
+          other than `none` is browser-only.
           If omitted, the project's stored default applies.
         style: form
         explode: false
@@ -4121,18 +4119,15 @@ paths:
       - name: headless
         in: query
         required: false
-        description: false runs the browser on a real display (1920x1080 screen instead of 800x600); only
-          engine=chromium supports it, anything else is 400 ERR::REQUEST::CAPABILITY_UNSUPPORTED at 0
-          credits. Either value requires a browser engine; omit to use the deployment default (headless).
-          Headful renders skip the warm pool and add ~1s. If omitted, the project's stored default applies.
-          Accepts true/false/1/0; a bare `?headless` means true.
+        deprecated: true
+        description: 'Deprecated and ignored. Rendering is chosen automatically. Accepted so existing clients keep working. The response carries `X-Warning: ENGINE_IGNORED`.'
         schema:
           type: boolean
       - name: screenshot
         in: query
         required: false
         description: Capture a screenshot; forces the JSON envelope (image base64 under `screenshots`).
-          Needs a rasterising engine (camoufox or chromium) - otherwise 400 ERR::REQUEST::CAPABILITY_UNSUPPORTED
+          Rendered with full-browser rendering - on a deployment without it, 400 ERR::REQUEST::CAPABILITY_UNSUPPORTED
           at 0 credits. mode=auto cannot satisfy it (its fetch rung has no rasteriser). If the image is
           not delivered the page is still returned but charged 0. Accepts true/false/1/0; a bare `?screenshot`
           means true.
@@ -4295,7 +4290,7 @@ paths:
         in: query
         required: false
         description: 'Body shape: html/markdown/text return the document itself, json the envelope, pdf
-          a browser-printed PDF (needs camoufox or chromium). extract, autoparse, links, ai_extract, network_capture
+          a PDF printed by a real browser (needs full-browser rendering). extract, autoparse, links, ai_extract, network_capture
           or screenshot override this to the JSON envelope with X-Warning FORMAT_COERCED. A non-HTML target
           (image, binary) requested as markdown/text fails 502 ERR::EXTRACT::FAILED at 0 credits. If omitted,
           the project''s stored default applies.'
@@ -4397,7 +4392,7 @@ paths:
               schema:
                 type: integer
             X-Request-Cost:
-              description: Price of the engine/proxy tier that ran (on a cache hit, the tier that fetched
+              description: Price of the rendering/proxy tier that ran (on a cache hit, the tier that fetched
                 the stored copy). Differs from X-Credits-Charged exactly when nothing was billed.
               schema:
                 type: integer
@@ -4410,15 +4405,15 @@ paths:
                 type: integer
                 minimum: 0
             X-Engine:
-              description: Engine that ran. After an escalation (mode=auto, or a bot challenge climbing
-                to camoufox), the rung that served the page.
+              description: The rendering tier used, or the last one attempted - `fetch` (HTTP only), `js`
+                (JavaScript rendering) or `browser` (full-browser rendering). After an escalation (mode=auto,
+                or a bot challenge escalated to stronger rendering), the tier that served the page.
               schema:
                 type: string
                 enum:
                 - fetch
-                - obscura
-                - camoufox
-                - chromium
+                - js
+                - browser
             X-Proxy-Source:
               description: Whose exit carried the request.
               schema:
@@ -4441,15 +4436,15 @@ paths:
               schema:
                 type: string
             X-RateLimit-Limit:
-              description: Requests per second allowed for this key/org.
+              description: Size of the key's rate-limit bucket, the most requests that can be sent back to back.
               schema:
                 type: integer
             X-RateLimit-Remaining:
-              description: Tokens left in the bucket.
+              description: Requests left in that bucket. Never above `X-RateLimit-Limit`.
               schema:
                 type: integer
             X-RateLimit-Reset:
-              description: Seconds until retry is allowed; only sent when the limiter imposed a wait.
+              description: Seconds until the bucket has one request available again; only sent when the limiter imposed a wait.
               schema:
                 type: integer
             Concurrency-Limit:
@@ -4470,7 +4465,7 @@ paths:
                 - bypass
             X-Warning:
               description: 'Repeated, one per advisory, formatted `CODE: message`. Codes: PROXY_FLAG_IGNORED,
-                FORMAT_COERCED, CACHE_TTL_CLAMPED, ENGINE_SUBSTITUTED, RENDER_DEGRADED, ESCALATED.'
+                FORMAT_COERCED, CACHE_TTL_CLAMPED, ENGINE_SUBSTITUTED (`served by JavaScript rendering` or `browser rendering`), ENGINE_IGNORED, RENDER_DEGRADED, EMPTY_RENDER (the render found no visible content and nothing was charged), ESCALATED (one per abandoned tier, naming the tier, its price and why: `ESCALATED: JavaScript rendering (3 credits): blocked by challenge page (Cloudflare …)`).'
               schema:
                 type: string
           content:
@@ -4489,7 +4484,6 @@ paths:
                       content-type: text/html; charset=utf-8
                     truncated: false
                     credits: 1
-                    engine: fetch
                     proxy_source: pool
                     warnings: []
                     data:
@@ -4513,7 +4507,6 @@ paths:
                       content-type: text/html
                     truncated: false
                     credits: 8
-                    engine: chromium
                     proxy_source: pool
                     warnings:
                     - '`screenshot` returns an image, which has no representation in a markdown body,
@@ -4579,17 +4572,18 @@ paths:
       description: |-
         Fetch one URL synchronously and return it as html, markdown, text, a PDF, or a JSON envelope with extracted data.
 
-        Choosing an engine (cheapest first):
-        - Default (fetch, 1 credit): plain HTTP, no JavaScript, presenting a current Chrome TLS/HTTP2 fingerprint (`impersonate`, on by default and free; `impersonate=false` turns it off).
-        - `js_render=true` (obscura, 3): content is built by JavaScript, or you need wait/wait_for/actions/block_resources/network_capture.
-        - `engine=chromium` (8): needed for screenshot and response_format=pdf. `stealth=true` (camoufox) is coming soon.
-        - `mode=auto`: unsure - escalates through the available engines, bills only the rung that worked.
+        How a request is rendered (cheapest first). You do not choose: Spicrawl picks the cheapest path that can do what the request asks.
+        - Default (plain fetch, 1 credit): plain HTTP, no JavaScript, presenting a current browser TLS/HTTP2 fingerprint (`impersonate`, on by default and free; `impersonate=false` turns it off).
+        - `js_render=true` (JavaScript rendering, 3 credits): content is built by JavaScript, or you need wait/wait_for/block_resources/network_capture.
+        - Screenshots, `response_format=pdf` and `actions` use full-browser rendering (8 credits). `stealth=true` (full-browser rendering hardened against bot detection, 25 credits) is coming soon.
+        - `mode=auto`: unsure - escalates through the available rendering tiers, bills only the tier that worked.
         - Managed proxy pools (`premium_proxy`) are coming soon; during the beta pass your own proxy with `proxy`.
+        - The `engine` and `headless` fields are deprecated and ignored.
         Browser-only flags on the fetch tier are a 400, never silently ignored.
 
         Billing: failures cost 0 (errors, bot challenges, timeouts, target statuses other than 200/404/410 unless listed in allowed_status_codes, undelivered screenshots). A cache hit is billed at the same price as the fetch that stored it: the cache saves the fetch (latency and load on the target), not credits. Like any request, a hit is refused with 402 when the monthly allowance cannot cover its price. Check X-Credits-Charged.
 
-        Bot challenges: a challenge page attributed to a named vendor (Cloudflare, DataDome, PerimeterX, Akamai) is never returned as a success. A fetch through a managed pool exit that meets one is retried once on a different exit, free (GET/HEAD/OPTIONS only, not with `sticky_key` or `session_id`, never on your own `proxy`). With `premium_proxy=true` or your own `proxy`, no `engine` pin and no `mode=auto`, a request whose page is still a challenge then climbs to camoufox, which waits out or clicks through the interstitial. Only the rung that returned the page is billed (camoufox 25, or the first rung's price), and 0 if every rung was challenged (502 ERR::UPSTREAM::CHALLENGE). A transport error, a refusal with no vendor marker (such as a bare 403) or a non-billable status such as 404 does not climb. The climb is left off for a non-GET method, headless=false, response_format=pdf, a screenshot, actions, a `proxy` that is not http://, a max_cost below the camoufox price, or a deployment without camoufox; an allowance that covers the first rung but not camoufox runs the request without it. X-Engine names the engine that served, each abandoned rung adds an `X-Warning: ESCALATED`, and diagnostics.attempts lists every attempt (in the JSON envelope on a successful climb). Batch items never climb.
+        Bot challenges: a challenge page attributed to a named vendor (Cloudflare, DataDome, PerimeterX, Akamai) is never returned as a success. A fetch through a managed pool exit that meets one is retried once on a different exit, free (GET/HEAD/OPTIONS only, not with `sticky_key` or `session_id`, never on your own `proxy`). When you bring your own `proxy` (residential works best) and send no `mode=auto`, a request whose page is still a challenge is escalated automatically to stronger full-browser rendering on the same exit, which works through the interstitial and returns the real page; there is no flag to set. This is how Cloudflare-protected pages are supported. Automatic handling on managed premium exits is coming soon. Success is not guaranteed for every page. Only the tier that returned the page is billed (up to 25 credits, or the first tier's price), and 0 if every tier was challenged (502 ERR::UPSTREAM::CHALLENGE). On the default shared pool a challenged page may return that error; retry with your own residential `proxy`. A transport error, a refusal with no vendor marker (such as a bare 403) or a non-billable status such as 404 does not escalate. Escalation is skipped for a non-GET method, response_format=pdf, a screenshot, actions, a `proxy` that is not http://, or a max_cost below the escalated price; an allowance that covers the first attempt but not the escalation runs the request without it. X-Engine reports the rendering tier that served, each abandoned tier adds an `X-Warning: ESCALATED`, and diagnostics.attempts lists every attempt (in the JSON envelope on a successful escalation). Batch items never escalate.
 
         Status: the HTTP status is the platform's. A blocked or erroring site is usually still HTTP 200 - read envelope `status` or X-Target-Status for the site's answer. Errors are application/problem+json; retry only when `retryable` is true.
 
@@ -4605,24 +4599,24 @@ paths:
             datacenter: 1
             residential: 10
             mobile: 10
-          obscura:
+          js_rendering:
             direct: 3
             datacenter: 3
             residential: 25
             mobile: 25
-          camoufox:
+          stealth_rendering:
             direct: 25
             datacenter: 25
             residential: 25
             mobile: 25
-          chromium:
+          full_browser_rendering:
             direct: 8
             datacenter: 8
             residential: 32
             mobile: 32
         custom_proxy: priced as the direct column (no proxy surcharge)
         ai_extract: 4
-        ai_extract_note: added on top of the engine price; the only additive item
+        ai_extract_note: added on top of the rendering price; the only additive item
         failures: 0
         cache_hit: the price of the fetch that stored it
         billable_target_statuses:
@@ -4632,7 +4626,7 @@ paths:
         billable_target_statuses_note: plus any in allowed_status_codes; other target statuses return
           the body at 0
         mode_auto: bills only the rung that succeeded; reserves the dearest rung against the monthly allowance
-        challenge_escalation: with premium_proxy or proxy, a vendor challenge may climb to camoufox; bills
+        challenge_escalation: with your own proxy, a vendor challenge may be escalated to stronger rendering; bills
           only the rung that returned the page, 0 if every rung was challenged; batch items never climb
         impersonate: 0
         extract_autoparse_links_network_capture: 0
@@ -4666,7 +4660,6 @@ paths:
                 summary: Rendered with actions and a screenshot
                 value:
                   url: https://example.com/pricing
-                  engine: chromium
                   wait_for: .plans
                   actions:
                   - click:
@@ -4696,7 +4689,7 @@ paths:
               schema:
                 type: integer
             X-Request-Cost:
-              description: Price of the engine/proxy tier that ran (on a cache hit, the tier that fetched
+              description: Price of the rendering/proxy tier that ran (on a cache hit, the tier that fetched
                 the stored copy). Differs from X-Credits-Charged exactly when nothing was billed.
               schema:
                 type: integer
@@ -4709,15 +4702,15 @@ paths:
                 type: integer
                 minimum: 0
             X-Engine:
-              description: Engine that ran. After an escalation (mode=auto, or a bot challenge climbing
-                to camoufox), the rung that served the page.
+              description: The rendering tier used, or the last one attempted - `fetch` (HTTP only), `js`
+                (JavaScript rendering) or `browser` (full-browser rendering). After an escalation (mode=auto,
+                or a bot challenge escalated to stronger rendering), the tier that served the page.
               schema:
                 type: string
                 enum:
                 - fetch
-                - obscura
-                - camoufox
-                - chromium
+                - js
+                - browser
             X-Proxy-Source:
               description: Whose exit carried the request.
               schema:
@@ -4740,15 +4733,15 @@ paths:
               schema:
                 type: string
             X-RateLimit-Limit:
-              description: Requests per second allowed for this key/org.
+              description: Size of the key's rate-limit bucket, the most requests that can be sent back to back.
               schema:
                 type: integer
             X-RateLimit-Remaining:
-              description: Tokens left in the bucket.
+              description: Requests left in that bucket. Never above `X-RateLimit-Limit`.
               schema:
                 type: integer
             X-RateLimit-Reset:
-              description: Seconds until retry is allowed; only sent when the limiter imposed a wait.
+              description: Seconds until the bucket has one request available again; only sent when the limiter imposed a wait.
               schema:
                 type: integer
             Concurrency-Limit:
@@ -4769,7 +4762,7 @@ paths:
                 - bypass
             X-Warning:
               description: 'Repeated, one per advisory, formatted `CODE: message`. Codes: PROXY_FLAG_IGNORED,
-                FORMAT_COERCED, CACHE_TTL_CLAMPED, ENGINE_SUBSTITUTED, RENDER_DEGRADED, ESCALATED.'
+                FORMAT_COERCED, CACHE_TTL_CLAMPED, ENGINE_SUBSTITUTED (`served by JavaScript rendering` or `browser rendering`), ENGINE_IGNORED, RENDER_DEGRADED, EMPTY_RENDER (the render found no visible content and nothing was charged), ESCALATED (one per abandoned tier, naming the tier, its price and why: `ESCALATED: JavaScript rendering (3 credits): blocked by challenge page (Cloudflare …)`).'
               schema:
                 type: string
           content:
@@ -4788,7 +4781,6 @@ paths:
                       content-type: text/html; charset=utf-8
                     truncated: false
                     credits: 1
-                    engine: fetch
                     proxy_source: pool
                     warnings: []
                     data:
@@ -4812,7 +4804,6 @@ paths:
                       content-type: text/html
                     truncated: false
                     credits: 8
-                    engine: chromium
                     proxy_source: pool
                     warnings:
                     - '`screenshot` returns an image, which has no representation in a markdown body,
@@ -4916,8 +4907,6 @@ paths:
                   - https://example.com/products/1
                   - https://example.com/products/2
                   js_render: true
-                  premium_proxy: true
-                  proxy_country: us
                   concurrency: 20
               itemsWithOverrides:
                 summary: Per-item overrides and correlation ids
@@ -5237,7 +5226,10 @@ paths:
           content:
             application/json:
               schema:
-                description: The item payload exactly as stored by the worker.
+                description: The item payload as a single JSON string literal holding the document in the item's
+                  `response_format` (html, markdown or text). A raw HTTP client decodes it once. This differs from
+                  `result.content` on the results stream, which is already plain text. For `json` the string holds
+                  the JSON document, which you then parse.
         '400':
           $ref: '#/components/responses/BadRequest'
         '401':
@@ -5496,7 +5488,7 @@ paths:
       operationId: sessionsCreate
       summary: Create a persisted browser session
       description: |
-        Creates a session: a sealed cookie jar and web-storage snapshot, pinned to one engine and one
+        Creates a session: a sealed cookie jar and web-storage snapshot, pinned to one
         exit intent, that you reuse by passing its `id` as `session_id` on `/v1/scrape`.
 
         Pitfalls:
@@ -5509,14 +5501,11 @@ paths:
           Omitting both pins the exit: `sticky_key` is derived from the session id.
         - `ttl_seconds` above the organization's maximum is refused (400), never clamped. It slides on use
           but never past `hard_expires_at`.
-        - `proxy_country` requires `premium_proxy: true`. `fingerprint` requires `engine: camoufox`.
+        - `proxy_country` requires `premium_proxy: true`. `fingerprint` is an advanced option and may be refused with 400.
         - A project may hold only one active session per `sticky_key` (409 `ERR::REQUEST::CONFLICT`).
         - An organization may hold at most 100 live sessions (429 `ERR::LIMIT::SESSIONS_EXCEEDED`,
           Retry-After 30).
-        - When `engine` is omitted, the default is the first of `obscura`, `chromium` that the deployment runs,
-          else `fetch`. Check the `engine` in the response.
-        - An explicit `engine` must be `fetch` or a render engine this deployment runs; otherwise 503
-          `ERR::ENGINE::UNAVAILABLE` and nothing is created. The detail lists the deployed engines.
+        - `engine` is optional (`fetch`, `js` or `browser`): omit it and the session's rendering is chosen for you. Scrapes with the session run on that tier, so a `js` session refuses `actions`, `block_resources`, a screenshot and a PDF (400 `ERR::REQUEST::CAPABILITY_UNSUPPORTED`).
       security:
       - bearerAuth: []
       x-spicrawl-scope: sessions
@@ -5528,17 +5517,13 @@ paths:
               $ref: '#/components/schemas/SessionCreateRequest'
             examples:
               pinnedLogin:
-                summary: Pinned residential exit in Germany, 2-hour TTL
+                summary: Pinned exit, 2-hour TTL
                 value:
-                  engine: chromium
                   ttl_seconds: 7200
-                  premium_proxy: true
-                  proxy_country: de
                   sticky_key: acct-4812
               importLogin:
                 summary: Seed with an existing login
                 value:
-                  engine: obscura
                   rotate_ip: true
                   session_context:
                     cookies:
@@ -5568,12 +5553,10 @@ paths:
                   value:
                     id: 01J9ZQ4M7R3T8VX2K5N6P0B1CD
                     project_id: 01J9Y0000000000000000PROJ1
-                    engine: chromium
                     status: active
                     sticky_key: acct-4812
                     proxy:
-                      tier: residential
-                      country: de
+                      tier: datacenter
                     created_at: '2026-09-22T10:00:00Z'
                     last_used_at: null
                     expires_at: '2026-09-22T12:00:00Z'
@@ -5634,14 +5617,13 @@ paths:
           default: 50
       - name: engine
         in: query
-        description: Only sessions pinned to this engine. Case-insensitive.
+        description: Optional. Only sessions bound to this rendering tier.
         schema:
           type: string
           enum:
           - fetch
-          - obscura
-          - chromium
-          - camoufox
+          - js
+          - browser
       - name: status
         in: query
         description: Only sessions whose clock-derived status matches. Case-insensitive. Filtered after
@@ -5674,12 +5656,10 @@ paths:
                     sessions:
                     - id: 01J9ZQ4M7R3T8VX2K5N6P0B1CD
                       project_id: 01J9Y0000000000000000PROJ1
-                      engine: chromium
                       status: active
                       sticky_key: acct-4812
                       proxy:
-                        tier: residential
-                        country: de
+                        tier: datacenter
                       created_at: '2026-09-22T10:00:00Z'
                       last_used_at: '2026-09-22T10:05:12Z'
                       expires_at: '2026-09-22T12:05:12Z'
@@ -5937,11 +5917,10 @@ paths:
       tags:
       - Browser
       operationId: browserConnect
-      summary: Coming soon. Open a Chrome DevTools Protocol WebSocket to a cloud browser
+      summary: Coming soon. Open a DevTools Protocol (CDP) WebSocket to a cloud browser
       description: |
         Coming soon.
-        A WebSocket upgrade, not a JSON endpoint. Connect with `puppeteer.connect({browserWSEndpoint})` or
-        `chromium.connectOverCDP(url)`. Authenticate with, in order of preference: `Authorization: Bearer <key>`
+        A WebSocket upgrade, not a JSON endpoint. Connect with any CDP client, using the URL as its browser WebSocket endpoint. Authenticate with, in order of preference: `Authorization: Bearer <key>`
         on the upgrade; a single-use `token` from `POST /v1/browser/token` (60 s, one connection, bound to its
         options — the URL the CLI and MCP return); or the `apikey` query parameter (`api_key` alias), kept for
         ZenRows-style URLs. When `token` is present it is the only credential consulted. Requires the
@@ -5960,7 +5939,7 @@ paths:
         `byte_limit` (the deployment's per-session traffic cap was reached, if configured),
         `upstream_closed` (the browser went away).
 
-        Pricing: a session costs 8 credits per started minute, the same as one real-Chromium page. At
+        Pricing: a session costs 8 credits per started minute, the same as one full-browser-rendered page. At
         admission the session HOLDS the price of its whole `session_ttl` against the monthly credit
         allowance (default `session_ttl` 180 s = 24 credits; 60–900 s range = 8–120 credits). At close it
         is charged for the minutes it actually held (rounded up, capped at `session_ttl`'s minutes) and
@@ -6013,14 +5992,16 @@ paths:
           type: string
       - name: engine
         in: query
-        description: Which browser serves the session. Case-insensitive. `fetch` and `camoufox` are refused
-          with 400 because neither speaks CDP. Omitted means the deployment default, `chromium`.
+        description: Optional. The rendering tier of the cloud browser - `browser` (default; full browser,
+          full protocol) or `js` (lighter JavaScript rendering with a smaller protocol surface; `headless=false`
+          is refused). `fetch` runs no browser and is refused with 400. A tier the plan does not include is 403
+          `ERR::AUTH::ENGINE_NOT_ENTITLED`; one the deployment lacks is 501 `ERR::ENGINE::UNAVAILABLE`.
         schema:
           type: string
           enum:
-          - chromium
-          - obscura
-          default: chromium
+          - browser
+          - js
+          default: browser
       - name: proxy_region
         in: query
         description: Broad exit region such as `eu`. Case-insensitive. `global` means no constraint and
@@ -6050,9 +6031,8 @@ paths:
           default: 180
       - name: headless
         in: query
-        description: '`true`/`1` or `false`/`0` (case-insensitive); anything else is 400. Omitted defers
-          to the deployment. `false` attaches a display. `headless=false` with `engine=obscura` is refused
-          with 400 `ERR::REQUEST::INCOMPATIBLE_FLAGS`.'
+        description: 'Optional and legacy. The display mode is chosen automatically; leave it out. If sent,
+          it is `true`/`1` or `false`/`0` (case-insensitive); anything else is 400.'
         schema:
           type: string
           enum:
@@ -6157,7 +6137,10 @@ paths:
               properties:
                 engine:
                   type: string
-                  enum: [chromium, obscura]
+                  enum:
+                  - browser
+                  - js
+                  default: browser
                 proxy_country:
                   type: string
                   pattern: '^[a-z]{2}$'
@@ -6306,7 +6289,6 @@ paths:
                     - id: 01M0FK1EP2E7FBMWAR7W10SMXW
                       created_at: '2026-09-22T12:41:22.183Z'
                       project_id: 01M0FJZ8Q3W4B5T8J2V9K6X1RD
-                      engine: chromium
                       status: blocked
                       http_status: 403
                       error_code: ERR::UPSTREAM::CHALLENGE