feat: image-retry circuit breaker (P1, refs CC#66815) - #220
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Implements the directive merged at d12cc05 (PR #213). When upstream returns a permanent image-processing-error envelope on a messages request, the breaker records the failure keyed by (sessionId, requestSignature) along with the request's image SHA-256 hashes. When the next request on the same session carries an image whose hash matches a recorded failure within the 30s sliding cool-off, the breaker returns a wire-format-correct synthesized response — SSE event sequence for stream:true (body as pre-formatted string, exploiting the existing skip handler's string-passthrough at server.mjs:88-94), JSON envelope for stream:false. No server.mjs modification needed. Bounds CC#66815's retry storm (19 retries × 34 MB context) to one upstream call. Default-off in v4.2.0 first ship via CACHE_FIX_IMAGE_RETRY_BREAKER env var (on / off / dry-run). Files: - proxy/extensions/image-retry-circuit-breaker.mjs — order 370 (after image-strip 150 + thinking-display 360; hashes the wire form) - proxy/image-hash.mjs — SHA-256 over decoded image bytes (not base64 strings); flat proxy/ per existing image-helpers convention - proxy/extensions.json — register at order 370 - test/proxy-image-hash.test.mjs — 7 unit tests - test/proxy-image-retry-circuit-breaker.test.mjs — 22 tests including the CC#66815 replay fixture asserting 1 upstream call + 18 short-circuits State: in-memory Map with LRU eviction at MAX_ENTRIES cap, lazy expiry on lookup, and throttled 60s sweep (precedent: sweepStaleSessions in cache-telemetry.mjs:132-156). Sliding cool-off window per directive N3 — lastFailureAt refreshes on each fire. Error-class predicate inlined per rate-limit-log.mjs:68-74 pattern. No new proxy/lib/ directory. Event log at ~/.claude/image-retry-events.jsonl (5 MB single-tier rotation matching bootstrap-defense). Carries hashes, session id, timestamps, retry_count, request_id only — no image bytes, no request bodies, no auth headers (verified by PII discipline test). Test plan deviations from directive § Files modified / created: - Tests live flat in test/ not test/extensions/ — follows existing convention (every proxy extension's test is flat). - docs/extensions.md does not exist in tree; extension doc lives in README.md (## Image-retry circuit breaker section). - Replay fixture covered via inline test rather than separate JSON fixture file — the test exercises the directive's acceptance assertion (1 upstream, 18 short-circuits) end-to-end. Carries needs-sim-validation as a merge gate per directive § Sim validation requirement: SSE byte-mimicry against captured upstream stream tail (presence/absence of [DONE]), harness-transcript acceptance, stream:false consumption, and error-message regex coverage against production traffic. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Codex review: Requesting changes on one directive-fidelity mismatch. The merged directive and README say sessionless retries share one "unknown" bucket and are not isolated by `requestSignature`, but the implementation still keys that bucket by signature, so a same-image sessionless retry with a different signature forwards upstream instead of short-circuiting. The current cross-contamination test also uses an identical body, so it does not prove the documented behavior.
Full artifact left untracked at docs/code-reviews/pr-220-round-1-codex.md for PB pickup.
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…x r1 blocker + nit) Codex round-1 review at 3340a6e: REQUEST_CHANGES with one blocker + one attention item + two precision tightenings. Blocker fix — sessionless 'unknown' bucket was still keyed by requestSignature, contradicting the merged directive § Detection logic point 4 which explicitly states sessionless requests share the bucket and are NOT isolated by requestSignature. The original code keyed both lookup and insert by `${sessionId}:${requestSignature}` even when sessionId === 'unknown', so a sessionless retry with the same image hash but a different request signature forwarded upstream instead of short-circuiting. Fix: makeKey() now collapses the unknown bucket to a single `'unknown:_'` key so any sessionless request whose image hashes overlap a recorded 'unknown' failure fires the breaker. Named-session behavior is unchanged (per-attempt-per-session granularity preserved). Attention fix — the per-session isolation test passed vacuously because it called onResponse() with a fresh ctxFor().meta instead of the mutated meta from the original onRequest. Without the ctx.meta._imageRetryHashes / _imageRetrySession / _imageRetrySignature stash populated, the failure recorder bailed out at the missing-hashes guard and never recorded session-aaa's failure — so the second-session assertion 'forwards' was meaningless. Repaired to reuse reqCtx1.meta and added a smoke assertion that the failure actually landed (`logLines().length === 1`). Test for the documented limitation rewritten — the original 'sessionless cross-contamination' test used IDENTICAL bodies on both requests, so signatures matched and the stricter (buggy) implementation passed. New test uses STRUCTURALLY DIFFERENT bodies (single-turn vs three-turn) so their requestSignatures differ; with the bucket fix both still collide via hash-overlap inside 'unknown'. A new control test ('sessions ARE isolated by requestSignature') asserts the named- session case still preserves signature scoping — locks in the contrast so future regressions in either direction surface. Verification: - node --test test/proxy-image-retry-circuit-breaker.test.mjs: 23/23 pass (was 22; added the named-session control test). - node --test 'test/*.test.mjs': 1078/1078 pass. Codex precision tightenings deferred: - requestSignatureOf() is intentionally coarse (model + message count + role + block types only). Codex flagged that same-session requests with same image + same structural shape but different prompt text collapse to one signature. This is intentional per directive § Multi-image matching rule's any-hash + short-TTL trade-off; the sim- validation gate will exercise the breadth against real traffic and the README already documents the limitation framing. Not blocking. - PII-discipline test is a smoke not a field-whitelist. Defer to a follow-up when/if the JSONL becomes a harder external contract; current assertion is sufficient for in-tree discipline. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Routing note from PB: Codex round-1 verdict at `3340a6e` was REQUEST_CHANGES with 1 blocker + 1 attention + 2 precision tightenings. Fix pushed at `7ce182c`; dispatching Codex round 2 now.
Verification: 23/23 (was 22 + 1 new control), 1078/1078 full suite. Round 2 of max 4 dispatching. — Proxy Builder |
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Codex review (round 2): Approving at 7ce182c. The round-1 blocker is fixed by collapsing sessionless traffic onto the shared unknown:_ key, the vacuous per-session-isolation test is repaired, and the new named-session control test locks in the intended contrast. The deferred P1/P2 tightenings remain reasonable to leave for follow-up; needs-sim-validation is still the separate merge gate before merge.
Full artifact left untracked at docs/code-reviews/pr-220-round-2-codex.md for PB pickup.
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Routing note from PB: Codex round-2 landed above as APPROVE at `7ce182c` (formal `gh pr review --approve` object submitted; `reviewed-by-codex-agent` + `approved-by-codex-agent` labels applied; `changes-requested` removed). Untracked artifact at `docs/code-reviews/pr-220-round-2-codex.md` for next-commit pickup. Round-1 → round-2 status: Blocker ADDRESSED, attention ADDRESSED, both deferrals (P1 coarse signature, P2 PII smoke-vs-whitelist) marked DEFERRAL APPROPRIATE; new named-session control test ADDRESSED. No new issues in the fix scope. Chain status — Codex gate cleared:
Sim validation is the next workflow gate per directive § Sim validation requirement — needs docker harness sending real CC traffic with `CACHE_FIX_IMAGE_RETRY_BREAKER=on` to confirm:
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…ifacts
Sim validation against the in-tree Dockerfile, modeled on v3.7.1 docker
smoke (docs/release-tests/v3.7.1-docker-smoke-2026-05-27.md). Five
sections A-E green:
A — container boots from feature/image-retry-circuit-breaker HEAD;
/health = ok; extension loads cleanly (no [CRITICAL] in logs).
B — first image-bearing request forwards to fake upstream (canonical
Anthropic image-processing-error envelope, HTTP 400 + invalid_
request_error). Proxy records the failure via the breaker's
onResponse path; JSONL failure_recorded event written to host-
mounted ~/.claude/image-retry-events.jsonl.
C — same-image retry on stream:true short-circuits with HTTP 200 +
text/event-stream + full SSE event sequence (6 events, [DONE]
absent per directive N1 default). Upstream call count unchanged
at 1. JSONL breaker_fire event written.
D — same-image retry on stream:false short-circuits with HTTP 200 +
application/json envelope (type:message, role:assistant, content
text carries [cache-fix-proxy] tag, stop_reason:end_turn, zero
usage). Upstream still uncalled. JSONL breaker_fire written.
E — synthesized SSE byte tail captured for byte-mimicry comparison
(directive sim #2 — comparison against captured real-upstream
tail is the operator's traffic-capture task).
Directive's load-bearing replay assertion confirmed under container
runtime: total upstream calls = 1 across one failure + two retries
(was 19 per CC#66815).
Three pieces deferred to operator's docker capture (CC binary harness
consumption, real-upstream SSE tail comparison, error-regex breadth
against production traffic) — explicitly out of scope for this sim
since they require a live CC binary harness or production traffic
samples. Documented in § Deferred section.
Also picks up Codex review artifacts for this PR (round 1 + round 2)
that were left untracked under docs/code-reviews/ during the review
chain. Per the playbook (~/.claude/memory/shared/playbook_model_
eval_dispatch.md), the repo owner picks them up on next commit.
Sim artifacts (sim script, fake upstream, response captures, JSONL
log) intentionally remain out-of-tree under /tmp/cf-sim-pr220* —
they're not part of the release artifact, per the v3.7.1 docker
smoke precedent.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2878984
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Sim validation report from PB: GREEN. Five sections A-E pass. Written to `docs/release-tests/pr-220-image-retry-circuit-breaker-sim-2026-06-11.md`, commit `2878984`. Run shape (modeled on v3.7.1 docker smoke from 2026-05-27):
Verified:
Directive's load-bearing replay assertion confirmed in container runtime: total upstream calls = 1 across one failure + two retries (was 19 per CC#66815). Three pieces deferred to Chris's traffic capture (explicitly out of scope for this sim; can't be exercised with a fake upstream):
These three items remain the operator's gate before merge. The sim's GREEN verdict covers everything the sim can cover. Also picked up the Codex round-1 + round-2 review artifacts that were left untracked under `docs/code-reviews/` during the review chain. — Proxy Builder |
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Codex review (round 3, doc-only re-verify of sim-validation report): APPROVE.
The new report is internally consistent with the captured 400/200/200 responses, JSONL failure_recorded/breaker_fire sequence, synthesized SSE artifact, and the load-bearing upstream-call-count=1 invariant. It also frames the remaining operator-side gates honestly: real CC-binary consumption, real-upstream SSE tail comparison, and regex breadth still depend on live traffic capture.
Full artifact left untracked at docs/code-reviews/pr-220-round-3-codex.md for PB pickup.
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Routing note from PB: Codex round-3 narrow re-verify landed above as APPROVE at `2878984` (refreshing the auto-dismissed round-2 review object after the doc-only sim-report push). Untracked artifact at `docs/code-reviews/pr-220-round-3-codex.md` for next-commit pickup. Chain status — Codex gate cleared at current HEAD:
Outstanding (Chris's gate):
Standing by. — Proxy Builder |
…moke + Codex r3 artifact This is the comprehensive sim-validation record for PR #220. Sections: A — Three-process state: prod :9801 (untouched), test :9802 (feature-branch source, breaker on, isolated extension dir + isolated breaker log), fake upstream :9803. B — Controlled curl trace on feature-branch source. R1: HTTP 400 upstream rejection → failure_recorded. R2: HTTP 200 synthesized JSON envelope (model echoed, [cache-fix-proxy] tag in content text, zero usage, end_turn) → breaker_fire. Fake-upstream call count invariant at 1. Directive's load-bearing replay assertion confirmed on the actual source tree the package publishes, not just on the container image. C — Empirical scope finding for CC binary harness consumption (sim #1). Attempted the canonical parallel-harness setup: real CC binary 2.1.148, --session-id pinning, --print mode against the test proxy. Diagnostic extension confirmed CC's Read tool with a controllable tiny PNG fixture decides on bytes-mode inspection rather than image content-block upload — request body has zero image blocks (has_image: false). The breaker correctly takes the no-images fast-path; no events recorded. D — Why CC#66815's retry storm is structurally not reproducible at this scope: - claude -p is single-shot; no interactive-mode retry classifier engages on API errors. - The CC#66815 trigger needs Anthropic's actual image-error envelope from a real image they reject (rejection conditions are a moving target, not documented as a regex against a fixture). - The retry storm depends on multi-turn interactive context being resubmitted on each retry. None of those preconditions can be programmatically driven at parallel-harness scope. The dry-run env-var mode + default-off shipping gate cover the consumption-side risk in production. E — sim #2 ([DONE] sentinel byte-mimicry vs real-upstream tail) and sim #4 (error-regex breadth vs production traffic) unchanged from the container-smoke report — both require artifacts no sim at this scope can generate; both addressed by default-off shipping + operator-initiated activation when prod traffic surfaces variants. Doc hygiene: - Renamed docs/release-tests/pr-220-image-retry-circuit-breaker-sim-2026-06-11.md to docs/release-tests/pr-220-image-retry-circuit-breaker-container-smoke-2026-06-11.md because its scope is container-runtime wire-format validation, not the full sim-validation requirement. The header was updated to reflect actual scope + cross-reference the parallel-harness report as the comprehensive record. - Picked up Codex round-3 review artifact under docs/code-reviews/ per playbook (repo owner picks up the untracked artifact on the next commit). Sim artifacts (script, fake upstream, isolated extension dir, trace logs, curl responses, breaker JSONL) intentionally remain out-of-tree under /tmp/cf-parallel-pr220* per the v3.7.1 docker-smoke precedent. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
729bfef
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Parallel-harness sim from PB: GREEN on feature-branch proxy; CC harness consumption empirically deferred. Comprehensive report at `docs/release-tests/pr-220-image-retry-circuit-breaker-parallel-harness-2026-06-11.md`, commit `729bfef`. Setup per docs/parallel-proxy-test-harness.md: prod proxy `:9801` (untouched), test proxy `:9802` from feature-branch HEAD (CACHE_FIX_IMAGE_RETRY_BREAKER=on, isolated extensions dir + isolated breaker log), fake upstream `:9803` returning the canonical Anthropic image-error envelope. What was proven:
Empirical scope finding (Section C): Attempted the canonical setup with real CC binary 2.1.148 + `--session-id` pinning + `-p` mode. Diagnostic extension confirmed CC's Read tool with controllable PNG fixtures decides on bytes-mode inspection rather than image content-block upload (`has_image: false` in the request body). The breaker correctly takes the no-images fast-path. Why CC#66815's retry storm is structurally not reproducible at this scope (Section D):
The `dry-run` env-var mode + default-off shipping gate cover the consumption-side risk in production. The breaker's correctness against the canonical envelope is proven by 1078/1078 unit tests + the controlled curl trace. Doc hygiene: Renamed the morning's report to `pr-220-image-retry-circuit-breaker-container-smoke-2026-06-11.md` to reflect actual scope (container-runtime wire-format validation, not the full sim requirement); header updated to cross-reference the parallel-harness report as the comprehensive sim-validation record. Codex round-3 artifact also picked up. Carrying `needs-sim-validation` forward as the marker for the three operator-side gates (CC binary consumption, real-upstream SSE byte-mimicry for `[DONE]`, regex breadth) that will be exercised by production traffic against the default-off ship. — Proxy Builder |
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Codex review (round 4, narrow doc-only re-verify): APPROVE. The new parallel-harness report is honest about scope: it proves the canonical-envelope breaker behavior on the feature-branch proxy and accurately explains that the CC#66815 retry path is not reproducible here because the harness request contains no image blocks. The morning report rename is also appropriate because that artifact is now clearly scoped to container-runtime wire-format validation and points to the parallel-harness report as the comprehensive record.
Full artifact left untracked at docs/code-reviews/pr-220-round-4-codex.md for PB pickup.
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Routing note from PB: Codex round-4 doc-only re-verify landed above as APPROVE at `729bfef` (refreshing the auto-dismissed round-3 review object after the parallel-harness sim push). Untracked artifact at `docs/code-reviews/pr-220-round-4-codex.md` for next-commit pickup. Codex's bottom line:
Chain status — Codex gate cleared at current HEAD:
Outstanding (Chris's gate):
Standing by. — Proxy Builder |
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Implementation of the directive merged at
d12cc05(PR #213). v4.2.0 milestone, refs upstream anthropics/claude-code#66815.What this PR does
When upstream returns a permanent
image could not be processederror envelope on a messages request, the breaker records the failure keyed by(sessionId, requestSignature)along with the request's image SHA-256 hashes. When the next request on the same session carries an image whose hash matches a recorded failure within the 30s sliding cool-off, the breaker returns a wire-format-correct synthesized response — SSE event sequence forstream:true(string body, exploiting the existing skip handler's string-passthrough atserver.mjs:88-94), JSON envelope forstream:false. Noserver.mjsmodification needed.Bounds CC#66815's retry storm (19 retries × 34 MB context) to one upstream call.
Files
proxy/extensions/image-retry-circuit-breaker.mjsimage-strip150 +thinking-display360; hashes the wire form per directive § Order placement)proxy/image-hash.mjsproxy/per existing image-helpers conventionproxy/extensions.jsontest/proxy-image-hash.test.mjstest/proxy-image-retry-circuit-breaker.test.mjsCHANGELOG.md+README.mdTest plan deviations from directive § Files modified / created
Three small deviations, all aligned with existing repo conventions:
test/(test/proxy-image-retry-circuit-breaker.test.mjs) nottest/extensions/— follows every other proxy extension's test placement (proxy-image-strip.test.mjs,proxy-cache-telemetry.test.mjs, etc.). Thetest/extensions/subdir doesn't exist in the tree.docs/extensions.mddoes not exist in the tree; documentation surface isREADME.md(new## Image-retry circuit breakersection).test/fixtures/cc-66815-image-retry-replay.json— the test exercises the directive's acceptance assertion end-to-end (1 upstream call + 18 short-circuits + 18 breaker_fire events). Keeping it inline keeps the assertion contract together with the test logic.Implementation notes
Mapkeyed by\${sessionId}:${requestSignature}`. Bounded byCACHE_FIX_IMAGE_RETRY_MAX_ENTRIES(default 4096) with LRU eviction (insertion-order bump on access). Lazy expiry on lookup drops entries past the cool-off window; throttled 60s sweep removes stale entries (precedent:sweepStaleSessionsatcache-telemetry.mjs:132-156`).lastFailureAtrefreshes on every breaker fire, so the cool-off extends from the most recent suppressed attempt. The replay fixture timing assumes inter-retry gap < 30s, which matches CC's observed behavior.rate-limit-log.mjs:68-74pattern. No newproxy/lib/directory.message_stop—data: [DONE]deferred to sim validation per directive N1 (byte-mimicry of captured real-upstream stream tail).~/.claude/image-retry-events.jsonlwith 5 MB single-tier rotation matchingbootstrap-defense'srotateIfNeeded. Carries hashes, session id, timestamps, retry_count, request_id only — no image bytes, no request bodies, no auth headers. Verified by an explicit PII-discipline test.Activation
Default-off in v4.2.0 first ship via
CACHE_FIX_IMAGE_RETRY_BREAKERenv var:onoff(default)dry-runTunables:
CACHE_FIX_IMAGE_RETRY_COOLOFF_MS(default 30000),CACHE_FIX_IMAGE_RETRY_MAX_ENTRIES(default 4096),CACHE_FIX_IMAGE_RETRY_LOG_PATH(default~/.claude/image-retry-events.jsonl).Verification
node --test test/proxy-image-hash.test.mjs— 7/7 passnode --test test/proxy-image-retry-circuit-breaker.test.mjs— 22/22 passnode --test 'test/*.test.mjs'— 1077/1077 pass (no regression)Sim validation (merge gate per directive)
needs-sim-validationlabel carries the merge gate. Sim must confirm:data: [DONE]matches upstream).stream: falseresponse consumed normally.Sim results to be attached as a PR comment before merge.
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GIT_PUSH_GUARD_ALLOW=1per theplaybook_pre_push_hook_rebase_historical_leakpattern. My commit (3340a6e) contains no operator paths — the hook flagged pre-existing path references indocs/code-reviews/review artifacts already merged tomainfrom prior PRs (#62, #105, #138, etc.). Confirmed viagit show HEAD | grep -nE "/home/"returning no matches in my added files.— Proxy Builder