release: prepare v0.2.0 — CHANGELOG, chart bump, README link (refs #62)

CHANGELOG.md

@@ -0,0 +1,111 @@
+# Changelog
+
+All notable changes to DART are documented here. This project follows
+[Semantic Versioning](https://semver.org/); the wire protocol (`Hash64`, the
+HRW score formula, `ChunkKey`, and epoch framing) is called out explicitly in
+every release's upgrade notes.
+
+## [v0.2.0] — 2026-08-26
+
+The first release since v0.1.0: **30 merged fix PRs** (#23–#44, #47, #48,
+#56–#61) plus packaging and discovery additions that landed as direct commits.
+No breaking changes; rolling upgrades from v0.1.0 are safe for well-formed
+inputs (see Upgrade notes).
+
+### Highlights
+
+- First tag containing the **Helm chart** (`deploy/helm/dart`) and **Fluid**
+  ThinRuntimeProfile/Dataset samples (`deploy/fluid`).
+- First tag containing the **Kubernetes EndpointSlice discovery** module
+  (`providers/k8s`, a separate Go module keeping the main module
+  dependency-free) and the `dart-k8s` command.
+- The minimalist design assumptions the cache semantics rest on are now
+  documented in one tracked place (`docs/design-assumptions.md`, #28).
+
+### Additions
+
+Four changes were committed directly (no PR) on 2026-08-13:
+
+- `2a53b2b` — `internal/node` extracted from `cmd/dart`; EndpointSlice
+  discovery added as the separate `providers/k8s` module with the `dart-k8s`
+  binary.
+- `8e6a6a3` — Helm chart for the DaemonSet shape (discovery.mode=dns|k8s) and
+  Fluid ThinRuntimeProfile + Dataset samples.
+- `b2b7d5b` — engine passes non-range origins straight through, uncached.
+- `f21f05d` — tracker evicts idle file entries.
+
+### Fixes
+
+- **engine / fetch data path**: validate relayed block length against geometry
+  before caching (#23); fail the size probe loudly when a 206 hides the total
+  (#25); bound the shared flight, cancel-aware joiner retry (#26); six audit
+  fixes — relay decline, hedge metrics, estimator, reader cache, stream
+  fallback, empty object (#33); past-EOF blocks error loudly, RFC-clamped tail
+  206 accepted (#38); reject suffix ranges on empty objects (#56); wait
+  coalescing joiners inline, one worker goroutine per flight (#60); reject peer
+  block indices that overflow signed range geometry (#61); redact credentials
+  from transport errors and the startup banner (#29).
+- **peer transport**: stop charging caller cancellation to the circuit
+  breaker; bound breaker state (#30); hard-bound the breaker map under
+  failed-address churn (#58); reject invalid `X-DART-Hop` values at both
+  servers (#57).
+- **cluster / membership**: credit liveness to the answering member's ID, not
+  the dialed address (#24); hearsay liveness, publication races, and
+  dedup-priority fixes (#35); member-ID alphabet guards the epoch framing;
+  lifecycle/tracker docs (#44); report invalid roster IDs via OnError; assert
+  the epoch-collision regression unconditionally (#47).
+- **store / metrics**: scope the TinyLFU estimator to borrowed traffic;
+  class-migration and admission fixes (#34); O(1) MemStore.Len via an atomic
+  counter and HELP text escaped per the Prometheus text format (#41).
+- **node lifecycle**: lifecycle hardening, flag validation, exact byte sizes,
+  routed+throttled diagnostics (#40); closeable admission gate — the store is
+  never closed under a live handler (#48).
+- **registry mirror**: document the real credential rule for the token realm
+  (#32); client-credential precedence, digest-classifier alignment, path
+  encoding, token-cache hygiene (#39); detach the token singleflight from the
+  leader's context (#59).
+- **tracker**: clamp client-supplied lease TTL; guard duration overflow (#27).
+- **wire-adjacent hardening**: separator exclusion, fallback query stripping,
+  score-comment honesty (#36); golden reference implementations committed for
+  hashring/chunk/cluster, weighted-rank goldens, zero-alloc tree navigation
+  (#37).
+- **docs / posture**: trusted-origin assumption for digest-keyed caching (#31);
+  the design-assumptions document (#28); `dart_block_fetch_seconds` inclusion
+  rules (#42); least-privilege RBAC, staleness posture, identity-flags pointer
+  (#43).
+
+### Upgrade notes
+
+Rolling upgrades from v0.1.0 are safe: all wire-protocol derivations — the
+`Hash64` construction, the HRW `score` formula, the `ChunkKey` mix sequence,
+and the epoch framing bytes — are **byte-identical** to v0.1.0 for well-formed
+inputs. Two derivations changed for edge inputs only:
+
+- Unparseable or scheme-less fallback URLs now cut the query/fragment, and
+  derived object identities strip a literal 0x1F byte (reachable via a
+  percent-encoded `%1F` in the path). A mixed-version cluster may split cache
+  identity for such malformed URLs — extra origin fetches, no correctness
+  impact (content still comes from the same origin; digest-addressed content
+  stays verified).
+- The duplicate-ID dedup winner in `NewView` now follows the lifecycle rank
+  Ready > Suspect > Joining > Leaving. This is only reachable when the same
+  member ID appears with different states in one input — realistically a
+  duplicated ID in a static `-peers` list.
+
+Peer-facing rejections (`X-DART-Hop` validation, the `MaxBlockIndex` bound)
+only affect traffic a v0.1.0 peer never legitimately produces.
+
+No configuration changes are required. The Helm chart bumps `appVersion` to
+`v0.2.0`; chart version moves to 0.2.0.
+
+### Verification
+
+At the tagged commit: `go vet ./...` clean; `go test ./... -race -count=1` —
+all packages pass; `go test ./... -cover -count=1` — all pass; GitHub Actions
+CI green.
+
+## [v0.1.0] — 2026-08-06
+
+Initial tagged release: read-only P2P cache node with weighted-HRW placement,
+preorder distribution tree, two-tier block store, registry pull-through
+mirror, dependency-free Prometheus exporter, and K8s/DNS discovery wiring.

README.md

@@ -244,6 +244,8 @@ HTTP-backed mounts are documented in the files' headers.
 
 ## Documentation
 
+Release history and upgrade notes live in [`CHANGELOG.md`](./CHANGELOG.md).
+
 [`docs/`](./docs) has a reference document per package — API, semantics,
 concurrency contract, test status and known limitations. Start with
 [`docs/README.md`](./docs/README.md) for the index, or

deploy/helm/dart/Chart.yaml

@@ -8,6 +8,8 @@ description: >-
   variant, RBAC created automatically).
 type: application
 # version is the chart version; bump it on every chart change.
-version: 0.1.0
-# appVersion tracks the DART image tag the chart defaults to.
-appVersion: "dev"
+version: 0.2.0
+# appVersion names the DART release (image tag) this chart version targets;
+# the default image.tag stays "dev" (source-build convention) — set it to this
+# value when deploying a tagged release.
+appVersion: "v0.2.0"

deploy/helm/dart/values.yaml

@@ -8,7 +8,10 @@ image:
   # repository is used as-is for discovery.mode=dns and gets a "-k8s" suffix
   # appended for discovery.mode=k8s (the Dockerfile's dart-k8s target), so the
   # default values below resolve to "dart:dev" and "dart-k8s:dev" respectively.
-  # Point this at your registry for production (e.g. ghcr.io/acme/dart).
+  # DART images are not published to any registry: build from source
+  # (docker build -t dart:<tag> .) or point repository at your own registry.
+  # For a tagged release build, set tag to the chart's appVersion (e.g.
+  # v0.2.0) so the deployed image matches what the chart was written for.
   repository: dart
   tag: dev
   pullPolicy: IfNotPresent