test(seed): pin the locale axis; docs, liveness ledger and changeset

Claude-Session: https://claude.ai/code/session_013r78utTbiWqxghcuRJxfZf
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

.changeset/seed-locale-axis.md

@@ -0,0 +1,16 @@
+---
+"@objectstack/spec": minor
+"@objectstack/metadata-protocol": minor
+---
+
+Seed datasets gain a `locale` filter axis, composed with `env` by the loader.
+
+An app shipping demo data for two language markets — the same records, different display strings — had no declarative way to say which dataset applies. `SeedSchema` is a `strictObject`, so the app could not add the key itself; the selection had to happen in application code while the config was assembled. That is the wrong layer twice over: the choice is cached in the build output (switching markets means deleting `dist`), and because every profile is an `upsert` and the loader only writes, the other market's rows stay resident in the database.
+
+- **`Seed.locale?: string[]`** — BCP-47 tags scoping the dataset to one or more language markets. **Omitted means every locale.** Unlike `env`, whose three environments are a closed set that can be spelled out as a default, locales are open-ended tags with no enumerable universe — so absence, not a default array, is what carries "unrestricted". An empty array is rejected: a dataset that applies nowhere is an authoring mistake, the same reasoning that already governs a composite `externalId`. `locales`, `language` and `languages` are aliased onto it, matching the existing `environment` / `environments` → `env` pair.
+- **`SeedLoaderConfig.locale?: string`** — the tag the load filters on.
+- **The loader composes both axes by conjunction.** A dataset is loaded when it passes `env` **and** `locale`; neither axis can rescue a dataset the other excluded. `filterByLocale` mirrors `filterByEnv` down to the reporting posture — skipping is the declared, intended outcome, so it logs at `info`, but it always names what it dropped. Tags compare case-insensitively (BCP-47 casing is a convention, not part of a tag's identity) and otherwise exactly: `['zh']` does not match `zh-CN`, and widening that would be the lenient consumer-side fallback the contract-first rule forbids.
+
+The platform still translates nothing and merges nothing. The app authors both record sets; this adds only the axis that selects between them.
+
+**What is not wired yet, stated plainly.** The locale axis is evaluated against `config.locale`, and no first-party call site supplies one — the runtime wiring that would resolve it from the stack's configured locale is a separate change in `packages/runtime`. An embedding host that passes `config.locale` itself gets the full behaviour today; on the default boot path the axis is inert. That is the shape `Seed.env` was in before framework#4704, so it is not left silent: a load carrying locale-scoped datasets and no `config.locale` warns naming each dataset it let through and the config key that would make the scope take effect. The liveness ledger records `seed.locale` as `experimental` for exactly this reason, with the consumer side cited and the producer gap spelled out, rather than claiming `live` on a correct-but-insufficient consumer pointer.

content/docs/data-modeling/seed-data.mdx

@@ -177,6 +177,53 @@ defineSeed(TestUser, {
 
 ---
 
+## Locale Scoping
+
+The `locale` array scopes a dataset to one or more language markets, as BCP-47
+tags. It is a second filter axis alongside `env`, and the two **compose**: a
+dataset loads when it passes `env` *and* `locale`.
+
+Omitting `locale` means **every locale** — unlike `env` there is no default
+array, because locales are open-ended tags with no closed set to spell out.
+
+```typescript
+// Reference data — every market (locale omitted)
+defineSeed(Country, {
+  records: [{ code: 'US', name: 'United States' }],
+});
+
+// The Chinese market's demo plans
+defineSeed(Plan, {
+  locale: ['zh-CN'],
+  records: [{ name: '专业版', price: 99 }],
+});
+
+// The same plans for English-speaking markets
+defineSeed(Plan, {
+  locale: ['en', 'en-GB'],
+  records: [{ name: 'Professional', price: 15 }],
+});
+```
+
+Tags are matched **case-insensitively** (`zh-cn` and `zh-CN` are the same tag)
+and otherwise **exactly** — `['zh']` does not match a loading locale of
+`zh-CN`. List every tag the dataset is for.
+
+The platform does not translate anything. `locale` only selects between record
+sets you authored yourself; both sets stay in your source tree, and the choice
+is made when the seeds load rather than when your config is assembled — so
+switching markets does not mean rebuilding, and the axis is evaluated in the one
+layer that could ever reconcile rows already written for another market.
+
+<Callout type="warn">
+  The axis is evaluated against the seed loader's `config.locale`. A host that
+  supplies no locale gets **every** dataset, and the loader warns naming each
+  locale-scoped dataset it let through — so a scope that is not taking effect is
+  one log line to diagnose rather than a silent no-op.
+</Callout>
+
+---
+
 ## Type Safety
 
 `defineSeed()` infers valid field keys from the object definition you pass as the
@@ -443,6 +490,13 @@ Keep demo and test-only records out of production by setting `env: ['dev', 'test
 System bootstrap data that must exist in production should omit `env` (or explicitly
 set `['prod', 'dev', 'test']`).
 
+### Ship one dataset per market, not one build per market
+
+When the same records need different display strings per language, author both
+datasets and scope each with `locale`. Selecting between them in application
+code instead bakes the choice into your build output and leaves the other
+market's rows resident in the database on a switch.
+
 ### Use `upsert` by default
 
 `upsert` is idempotent and the safest default. Only change the mode when the use
@@ -477,6 +531,7 @@ function defineSeed<
     externalId?: string | string[];         // single field, or a composite list (join tables); default: 'name'
     mode?: 'insert' | 'update' | 'upsert' | 'replace' | 'ignore'; // default: 'upsert'
     env?: Array<'prod' | 'dev' | 'test'>;  // default: ['prod','dev','test']
+    locale?: string[];                      // BCP-47 tags; omitted = every locale
     records: Array<Partial<Record<keyof TObj['fields'], unknown>>>;
   }
 ): Seed