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olp/docs
taodengandClaude Opus 4.7 bdfea6884b feat+docs+test: D39 — D16 follow-ups (issue #3, 4 parts)
D16 reviewer (commit `bafa6d1`) left 4 non-blocking suggestions
batched into issue #3 as a tracker. D39 closes all 4.

**Part 1 — CacheStore.delete(keyId, cacheKey) API** (lib/cache/store.mjs)

D16 originally evicted truncated entries via
`cacheStore.set(keyId, hopCacheKey, result, ttlMs=0)` — a TTL=0
tombstone purged lazily on next access. D39 introduces an explicit
delete primitive that removes the entry immediately.

- Synchronous: `delete(keyId, cacheKey) → boolean`. Returns true if
  the entry was present and removed, false if absent. Sync (not
  async) for the simplest in-memory Map contract — mirrors clear().
  Other CacheStore methods are async to leave room for a Phase 2
  file-backed adapter; delete being sync was a deliberate choice.
- Namespace cleanup: when the inner Map becomes empty after delete,
  the outer Map's per-keyId entry is also removed (memory hygiene;
  mirrors the _activeSpawns cleanup pattern from D38).
- Behavior: peek/get/getOrCompute see no trace after delete; the
  subsequent getOrCompute triggers a fresh compute.

**Part 2 — `cache_evicted_truncated` observability log** (server.mjs)

After the D16 eviction call in collectAllChunks, emit:
```js
logEvent('info', 'cache_evicted_truncated', {
  provider, model, cache_eviction_hit,
});
```

Dashboard sees salvage frequency per (provider, model). The
cache_eviction_hit boolean distinguishes "we evicted an entry" (true)
from "we tried to evict but it was already gone" (false — race with
concurrent eviction or TTL purge), preserving observability accuracy
under concurrency.

**Part 3 — Sticky-cache regression test** (test-features.mjs)

Defense-in-depth around the eviction path. Two consecutive identical
buffered requests; the first triggers SPAWN_FAILED after partial
chunks → Case B salvage returns `{ chunks..., finish_reason: 'length' }`
to the client and evicts via delete(). The second identical request
must trigger a fresh spawn (NOT serve the salvaged response from a
stale cache entry).

Asserts on BOTH invariants for defense-in-depth:
- Mock provider spawn count == 2 across the 2 identical requests
- Second request's X-OLP-Cache header is 'miss'

If eviction silently breaks in a future regression, both assertions
catch it independently.

**Part 4 — SPAWN_TIMEOUT salvage parity: DOCUMENT ASYMMETRY**
(docs/adr/0004-fallback-engine.md)

Maintainer decision: SPAWN_TIMEOUT is NOT salvaged. Document the
asymmetry rather than implementing parity. ADR 0004 Amendment 1 is
extended with a new section "Why SPAWN_TIMEOUT is excluded from
salvage" with 4-point rationale:

1. SPAWN_FAILED indicates the provider crashed mid-stream — there's
   nothing more coming; partial > nothing. Next-hop spawn has no
   advantage (same input may crash same way).
2. SPAWN_TIMEOUT indicates the provider was slow (deadline exceeded
   per `hints.maxSpawnTimeMs`). Fallback advancement to a DIFFERENT
   provider is more likely to give a complete response than salvaging
   a partial from a slow provider.
3. The "user paid for partial content" framing from D16 captures only
   SPAWN_FAILED. For SPAWN_TIMEOUT the user actually paid for "result
   within time T" — partial-at-time-T is not what was paid for;
   "full result soon after T" via fallback is closer.
4. Code-level inspection confirms the asymmetry: collectAllChunks
   catch matches ONLY `code === 'SPAWN_FAILED'` (server.mjs:563).
   SPAWN_TIMEOUT propagates via re-throw and hits evaluateHardTriggers.

v1.x re-evaluation trigger: if real usage shows users want partial-
on-timeout for very long deadlines, add a v1.x design ADR.

Stale comment fix: `lib/providers/anthropic.mjs:369` previously said
"SPAWN_TIMEOUT salvage parity is tracked in issue #3". D39 closes
that issue, so the comment is updated to point at ADR 0004 Amendment 1.

**Tests** (test-features.mjs): 447 → 452 (+5):
- 3 unit tests on CacheStore.delete (Suite 9): present-key true, absent-key
  false, namespace cleanup at empty
- 1 D16 integration test: cache_evicted_truncated log fires with
  correct fields during salvage
- 1 sticky-cache regression: spawn count 2 across 2 identical requests,
  X-OLP-Cache miss on second

Pre-commit fold-ins (per evidence-first checkpoint #4):

- **Reviewer Suggestion #1**: cacheStore.delete() return value was
  discarded at the call site → log inflated salvage metric under
  concurrent-eviction race. Folded: captured `evicted` boolean and
  added to log payload as `cache_eviction_hit`.
- **Reviewer Suggestion #2**: anthropic.mjs:369 stale comment
  pointing at now-closed issue #3. Folded: rewrote to point at
  ADR 0004 Amendment 1 § "Why SPAWN_TIMEOUT is excluded from
  salvage".
- **Reviewer Suggestion #3**: ADR 0004 attribution ambiguity —
  parenthetical "(per Amendment 3 — SPAWN_TIMEOUT is one of the 4
  live hard-trigger codes alongside SPAWN_FAILED, CLI_NOT_FOUND, and
  CONCURRENCY_LIMIT from Amendment 4)" could mis-parse as Amendment 3
  covering all four. Folded: split to
  "(per Amendment 3: SPAWN_FAILED, CLI_NOT_FOUND, SPAWN_TIMEOUT;
  per Amendment 4: CONCURRENCY_LIMIT)".

**CHANGELOG**: D39 sub-entry appended under the existing D38 entry
in Unreleased section. No package.json bump (phase_rolling_mode).

Authority:
- ADR 0005 § Cache layer — CacheStore API extension (Part 1)
- ADR 0004 Amendment 1 update — SPAWN_TIMEOUT asymmetry rationale (Part 4)
- GitHub issue #3 — closed by this commit
- D16 commit bafa6d1 non-blocking suggestions — batched here
- CC 开发铁律 v1.6 § 10.x — fresh-context opus reviewer independent
- CLAUDE.md release_kit_overlay phase_rolling_mode — under Unreleased

Reviewer (fresh-context opus, Iron Rule 10): APPROVE_WITH_MINOR.
Verified: delete() sync + call-site no-await correct; namespace
cleanup guarded on (had && ns.size === 0); SPAWN_TIMEOUT NOT in
salvage catch; ADR section 4-point rationale internally consistent
with code state; hygiene clean; 452/452 tests pass independently.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-24 21:13:57 +10:00
..