[vadymhimself]

Summary

• Refs Combo routes: let an Anthropic child replay the caller's Messages bytes (native lane) instead of re-translating them #7350. A Messages caller using an Anthropic-first failover combo currently takes Messages → Responses → Messages, rebuilding system/messages/tools/cache breakpoints. Reuse the existing native Messages executor through the existing native Chat combo source seam instead of porting the fork replay pipeline.
• Supported first slice: strict failover combos without a default effort, canonical https://api.anthropic.com Anthropic children, managed keys or eligible configured OAuth/pools, with existing native flags enabled. Each child starts from an independently charged source envelope. Existing model/auth/beta allowlisting, OAuth preamble/tool/metadata binding, image normalization and tool-id validation remain authoritative. Explicit operator cache retention still wins; otherwise TTL-less combo breakpoints are preserved.
• Existing combo selection, cooldown/failure classification, per-target/shared send budget, exact prepaid permit, attempt row, admission lease and gated final-log callbacks remain owners. A bounded Messages preflight allows retryable structured errors before output to fall back. Any content/tool block, malformed/unknown payload or cap commits conservatively; collected failures after commitment cannot replay. Cancellation retains observed usage; discarded-child transport cleanup detaches before aborting so it cannot settle its parent lease.
• Excluded: policy/JEV/other strategies, default/adaptive combo effort rewrites, effort/Fast rows or directives, pinned effort, explicit empty reasoning ladders, vision preprocessing and bridge-only sidecar/skill policies. Those retain the translated path. Logical combo count_tokens and config-only previews retain their existing estimates/declines. A source declaring a native-only tool (bash_*, text_editor_*, ... — anything the translated body drops with no out-of-body lane) makes every translated child unpickable, so a refused native child surfaces its own failure instead of silently continuing without the tool; web_search/web_fetch stay portable. No live cache-hit rate or paid generation was measured: stable serialized source-prefix equality is the evidence, not a cache-performance claim.

Verification

Bun test runner 1.4.3 (/tmp/bun-1.4.3/bun-darwin-aarch64/bun), dependencies installed with bun install --frozen-lockfile.

• RED before source edits on fresh upstream 79fa97be6: bun test tests/claude-integration/messages-native-combo.test.ts --test-name-pattern "canonical child preserves" failed at exact wire-body equality: translated child lost top_k, message/cache block shape and original system/tool prefix. No stash/checkout reversal used.

• GREEN bun test tests/claude-integration/messages-native-combo.test.ts: 15 cases including canonical original fields, serialized stable prefix after appending a turn, managed auth/OAuth binding, pre-output refusal fallback, no text/tool replay, non-stream/folded paths, native-disabled/pinned-policy translation, cancellation usage, exact-once lease release, rejected-native→accepted-native lease lifetime, enforced accounting and real loopback HTTP ingress with mocked canonical egress. No external generation calls.

• bun test tests/claude-integration/messages-native-combo.test.ts tests/claude-integration/messages-native-opaque-state.test.ts tests/responses/chat-native-combo.test.ts tests/server/server-combo-zero-output-failover.test.ts: 54 pass.

• Existing direct native Messages/OAuth and native Chat combo regression batch: 192 pass before final edge-case refinements; final focused native+opaque batch: 21 pass.

• bun run typecheck; bun run structure:check; bun run privacy:scan; git diff --check: pass. Layout/tooling, file-size ratchet, Lab boundary and Responses core-module guards: 71 pass.

• cd docs-site && bun install --frozen-lockfile && bun run build: pass.

• Repository changed runner bun scripts/test.ts --changed=upstream/dev: first run 15962 pass, 2 fail. Native opaque-state failure fixed and its focused suite passes. tests/cli/cli-connect-readiness.test.ts case "a rejected preferred runtime falls back without rewriting the saved selection" still fails isolated: expected 2 debug models --bundled probe calls, received none; CLI files are untouched. Final changed run: 15964 pass, 34 skip, 1 fail across 640 files (166.8s); only the same isolated CLI probe assertion fails. Full non-changed/cross-platform suites not run; this remains draft, not review-ready. Exact-head GitHub hygiene/target/label checks pass; Cross-platform CI, Catalog async contracts and React Doctor report action_required pending maintainer approval, not passing test evidence. Inline review comments were read after push: none at that observation.

• Triage follow-up at d74a77662 (rebased on dev bd5c2ea90): the messages-native-combo.test.ts mapping moved from layout.json into the layout-replay.json shard; its test-layout-expected.json registration is unchanged. The shared Anthropic SSE tap (tapAnthropicSseForLog, used by the direct passthrough and the managed lane) now logs an upstream error event with its mapped status and terminalStatus: "failed" instead of 200, and records usage on both client-cancel paths. (Superseded at 3f32aec3e: dropped, see the refresh below.) structure/clients/claude-desktop.md is updated to that contract and two direct-lane cases in claude-native-passthrough.test.ts pin it: both fail on clean dev bd5c2ea90 (71 pass / 2 fail) and pass here (73 pass).

• Pinned runner Bun 1.4.3: layout/tooling, structure-ssot, Lab boundary, file-size ratchet, native Messages, native passthrough and combo replay-principal suites: 472 pass / 0 fail. tsc --noEmit, structure:check, privacy:scan, git diff --check: pass.

• CLI readiness: tests/cli/cli-connect-readiness.test.ts "a rejected preferred runtime falls back without rewriting the saved selection" fails identically on a clean upstream/dev bd5c2ea90 worktree under Bun 1.4.3 (26 pass / 1 fail: expected two debug models --bundled probes, received none). It is a local-environment failure on dev, not a regression from this branch, which touches no CLI file.

• Refresh at 9009d08f0 (merge commit, no rebase/force push): merges dev 6f915d865 into the maintainer carry 400ab4153. Conflicts with Normalize upstream error details in request logs and Retry-After advice #8104 resolved: combo hop warnings use dev's classifyUpstreamCondition (no upstream text, so it covers the native Messages source too); the claude-desktop.md tap paragraph keeps dev's failureDetail/scanning text plus this branch's upstream-error-event status and cancel-usage rules; the native-combo refusal test now pins the row errorCode and that no upstream echo reaches the final row, since dev no longer writes upstreamError. Pinned Bun 1.4.4: messages-native-combo 30/0, messages-native-combo-framing 15/0, messages-native-clean-eof 50/0, messages-native 102/0, messages-native-oauth 63/0, messages-native-scope 32/0, messages-native-key-selection 27/0, messages-native-empty-inline 36/0, messages-native-opaque-state 6/0, messages-native-decline-trace 2/0, messages-shared-sse 13/0, claude-native-passthrough 74/0, chat-native-combo 27/0, responses-combo-exhausted-error 27/0, responses-combo-replay-principal 2/0, server-combo-zero-output-failover 16/0; layout tooling 27/0, layout 2/0, file-size ratchet 9/0, import-cycle ratchet 16/0, core-Lab boundary 25/0. tsc --noEmit, structure:check, privacy:scan pass. Full local suite not run; cross-platform CI is the full-suite evidence.

• Live evidence (real Anthropic, isolated home, 2026-10-27): on dev the translated combo lane reads 0 cached tokens on every turn and re-writes the whole prompt; this branch matches the direct native route token for token (see the evidence comment).

• Refresh at 3f32aec3e (merge commit, no rebase/force push): merges dev 0a30c5513. messages-native.ts takes dev's owned Messages error responses (fix(messages): normalize Messages error responses and Anthropic headers #8153/fix(messages): normalize streamed Messages error events #8164) with the combo commitment flag marking both fail and failEvidence non-replayable once preflight accepts. Scope reduced: the tap's upstream-error-event status and cancel-usage changes are dropped and messages-shared.ts, claude-desktop.md, claude-native-passthrough.test.ts and messages-native-clean-eof.test.ts now equal dev, because dev's executable parity goldens (messages-native-stream-parity, messages-sse-passthrough-errors) pin the existing rows and neither change is needed for native combo cache replay. Native-combo tests assert dev's normalized error wording (and that the upstream echo no longer reaches the client). Pinned Bun 1.4.4: messages-native-combo 35/0, messages-native-combo-framing 21/0, messages-native-clean-eof 50/0, messages-native 102/0, messages-native-oauth 63/0, messages-native-scope 32/0, messages-native-key-selection 27/0, messages-native-empty-inline 44/0, messages-native-opaque-state 6/0, messages-native-decline-trace 2/0, messages-native-stream-parity 30/0, messages-sse-passthrough-errors 7/0, claude-native-passthrough 73/0, chat-native-combo 27/0, responses-combo-exhausted-error 27/0, server-combo-zero-output-failover 16/0, protocol-envelope 4/0; layout tooling 27/0, layout 2/0, file-size ratchet 9/0, structure-ssot 51/0, core-Lab boundary 25/0. bun run typecheck, structure:check, privacy:scan pass. Full local suite not run; CI is the full-suite evidence.

• Refresh at 3df2b15a5 (merge commit 932df89c4, no rebase/force push): merges dev 3dc406051; the providers-and-adapters.md conflict keeps dev's translated-system-cache text plus this branch's native combo replay TTL sentence. Review fixes: combo judging reads the source in place via an uncharged envelope.readBody(), so judging cannot refuse the turn on the translator budget; a declared web_fetch_* keeps a non-first-party-Anthropic translated child unpickable; an ocx-route-chosen combo answers with the caller's model; an empty-content JSON answer records no first output; protocol-paths.md envelope paragraphs updated. Four new regressions fail before the fix and pass after. Pinned Bun 1.4.4: native Messages (incl. combo), native passthrough, Anthropic passthrough, native Chat combo, protocol, layout/tooling and file-size ratchet suites 1023 pass / 0 fail across 41 files; typecheck, structure:check, privacy:scan pass.

• Follow-up 863dc3e51: a restricted web_search_* is fenced like web_fetch_* (only a first-party Anthropic child carries it), and a failed native child releases its charged body copy before failover. Two more regressions fail before and pass after. Pinned Bun 1.4.4: native Messages, combo, passthrough, translated server tools, Claude inbound, native Chat combo, protocol, layout/tooling and file-size ratchet suites 1122 pass / 0 fail across 43 files; typecheck, structure:check, privacy:scan, git diff --check pass.

• Refresh at c21156a5c (merge commit, no rebase/force push): merges dev 250ef01ae (was 16 behind; no conflicts). Pinned Bun 1.4.4: same 43-file native Messages/combo/passthrough/native Chat combo/protocol/layout/file-size batch 1122 pass / 0 fail; typecheck, structure:check, privacy:scan pass.

• Refresh at e73d59491 (merge commit, no rebase/force push): merges dev 4b821cf29. Conflict with fix(workflows): enforce root send ceilings at physical admission #8149 in messages-native.ts: the combo child keeps its shared send-budget branch and the standalone path takes dev's spend gate (charge({ workflowAlreadyCounted: true })), its line kept verbatim for the workflow-refusal source fixture. Fixes against dev guards this branch had been missing: handleNativeMessages is no longer async, restoring dev's read-turn timing for the direct native SSE relay (messages-sse-native-errors golden rows); the combo preflight's local failures answer fixed literals (registered in the W2 messages-error-contracts table) instead of raw error text. Behaviour note: combo judging reads the source in place, so eligibility takes no copy; in responses-combo-exhausted-error a cooled primary that is still eligible for the request now answers with its cooldown (503 + Retry-After) instead of the fallback's 401, and eligibility no longer overflows the budget.

• Validation at e73d59491, pinned Bun 1.4.4: repository runner bun scripts/test.ts --changed=upstream/dev 53846 pass / 637 skip / 7 fail across 2454 files (run before the merge commit; one build error in it came from the then-unstaged conflict and is gone). The failing files cli-connect-readiness, catalog-omit-disabled-native, codex-cli-update-apply, codex-composed-acceptance and update-stop-first fail identically on a clean dev 4b821cf29 worktree (same pass/fail counts); management-integration-routes passes 106/0 after the commit. Focused 88-file Messages/combo/passthrough/native Chat combo/protocol/layout/file-size batch plus fix(workflows): enforce root send ceilings at physical admission #8149's tests: 2160 pass after the fixes; typecheck, structure:check, privacy:scan, git diff --check pass.

• Refresh at 68152bdb1 (merge commit 800bafec3, no rebase/force push): merges dev 6df9e1176 (was 13 behind; no conflicts). Fixes for the 2026-11-07 maintainer reviews on e73d594: a committed non-streaming fold that collects a malformed or mismatched error event returns its 502 marked non-replayable; a preflight buffer failure after the tap saw a content frame is marked non-replayable on both lanes; the observe-only combo send reports its start as already counted (as native Chat does), so a two-send root is not exhausted by one physical send; the shared tap publishes the usage it already received on reader-cancel and signal-abort, and the fold binds it before its 499; a 200 stream whose terminal was an upstream error event closes its combo child as failed with that error's status (recorded as logCtx.streamErrorStatus; the direct passthrough row is unchanged). The 895a859 parity goldens (messages-native-stream-parity, messages-sse-*-errors) keep every other fact and now allow only the cancel rows' newly kept usage. Seven new regressions fail on 800bafec3 and pass here.

• Validation at 68152bdb1, pinned Bun 1.4.4: repository runner bun run test 61349 pass / 674 skip / 39 fail across 2950 files before the golden exception; after it the 10 affected Messages/SSE/combo files are 233 pass / 0 fail. Remaining failures are not from this branch: ci-bun-install-frozen fails 21/3 identically on a clean dev 6df9e1176 worktree, and catalog-omit-disabled-native, cli-connect-readiness, codex-composed-acceptance and update-stop-first are the same dev-baseline failures recorded at e73d59491. typecheck, structure:check, privacy:scan pass.

• Fix at ee0e35f80 (0 behind dev 6df9e1176): the native Messages preflight now classifies each chunk before retaining it and holds a committing chunk (content, unknown event, malformed frame) without a charge, as the frame cap already does, so a retention refusal can only meet a still-replayable prelude. This replaces the generationStartedAt check from 68152bdb1, which missed an unknown event. Regressions a buffer refusal cannot replay a content frame / an unknown event fail with the old preflight and pass here. Pinned Bun 1.4.4: all tests/claude-integration/messages-* files plus claude-native-passthrough, chat-native-combo, responses-combo-exhausted-error, server-combo-zero-output-failover: 1160 pass / 0 fail across 45 files; typecheck, structure:check, privacy:scan pass.

Checklist

• Scope stays focused and avoids unrelated cleanup.
• Docs or release notes were updated when needed.
• Security-sensitive changes were reviewed for secrets, auth, and unsafe defaults.

Review readiness checklist

This PR stays in draft until every box below is ticked. Tick all four boxes once the requirements are met:

• Required local validation passed; commands, results, and any full-suite exception are documented.

• I pushed my PR to a recent dev commit (at most 10 behind; a maintainer may still ask for the exact tip before merge).

• I resolved all correct Codex and CodeRabbit findings.

• My PR is ready for review.

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features
  • Eligible direct Anthropic routes and canonical Anthropic children in strict failover combos can handle Messages requests natively when no default effort rewrite is required.
  • Native Messages support includes eligible configured OAuth accounts and account pools.
  • Native requests preserve prompt-cache breakpoints unless retention is explicitly configured.
• Bug Fixes
  • Retryable errors before output can fall back to another combo option; responses are not replayed once output begins.
  • Routes that would drop declared tools during translation are excluded from translated fallback.
• Documentation
  • Updated protocol-path and configuration guidance to describe native Messages eligibility and remaining bridge-only cases.

[github-actions]

✅ Deterministic PR hygiene checks passed.

[github-actions]

✅ READY

• all PR quality gates passed; the review readiness checklist is complete.

Review readiness checklist

• ✅ Required local validation passed; commands, results, and any full-suite exception are documented.
• ✅ I pushed my PR to a recent dev commit (at most 10 behind; a maintainer may still ask for the exact tip before merge).
• ✅ I resolved all correct Codex and CodeRabbit findings.
• ✅ My PR is ready for review.

✅ 4/4 boxes ticked.

This pull request has been marked Ready for Review.
The review-ready label marks this PR as ready; review automation runs independently.
Maintainers notified: @lidge-jun @Ingwannu

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✅ Deterministic PR hygiene checks passed.

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Walkthrough

Eligible Anthropic Messages requests can use the native path as strict failover combo children when no combo default effort applies. The implementation shares combo execution controls, filters candidates that would lose required tools, and preflights responses before forwarding output.

Changes: Native Messages eligibility and selection

Layer / File(s)	Summary
Messages ingress and child selection src/claude/inbound-content-options.ts, src/server/claude-messages.ts, src/server/responses/core-combo-native.ts, src/server/responses/core-combo.ts, src/server/responses/core-options.ts	Messages ingress supplies a native source for qualifying combo requests. Candidate selection applies strict failover eligibility and prevents translated children from dropping native-only tools.
Eligibility documentation and routing tests docs-site/src/content/docs/guides/claude-code.md, docs-site/src/content/docs/guides/protocol-paths.md, docs-site/src/content/docs/tr/guides/protocol-paths.md, docs-site/src/content/docs/reference/configuration/server.md, structure/data-planes/protocol-paths.md, tests/claude-integration/messages-native-combo.test.ts	Documentation describes eligible routes, OAuth account pools, and bridge-only cases. Integration tests cover routing, caller scope, tool compatibility, OAuth, and translated paths.

Shared combo execution and controls

Layer / File(s)	Summary
Shared executor, budgets, and body-copy charges src/server/messages-native.ts, src/protocols/envelope.ts, src/server/responses/core-combo-native.ts	Native execution reuses the combo attempt, send budget, permit, admission lease, and callbacks. ProtocolEnvelope.releaseBody() returns the retained charge for a cloned request body.
Execution accounting and lifecycle validation tests/claude-integration/messages-native-combo.test.ts, tests/responses/responses-combo-exhausted-error.test.ts, tests/fixtures/test-layout-expected.json, scripts/test-layout/layout-replay.json, structure/transports/responses-spend.md, structure/transports/responses.md, structure/data-planes/protocol-paths.md, structure/providers-and-adapters.md	Tests cover shared spend accounting, leases, first-output timing, and body-copy charges. Documentation describes shared controls and prompt-cache breakpoint retention.

Response preflight and terminal handling

Layer / File(s)	Summary
Bounded SSE preflight and stream forwarding src/server/messages-native-preflight.ts, src/server/messages-native.ts, src/server/responses/core-combo.ts	Preflight retains a bounded stream prefix, classifies eligible pre-output errors, and replays retained chunks for accepted streams. Content, malformed or unknown frames, and other commitment conditions prevent replay.
Framing tests and transport documentation tests/claude-integration/messages-native-combo-framing.test.ts, tests/claude-integration/messages-native-combo.test.ts, scripts/test-layout/layout-replay.json, tests/fixtures/test-layout-expected.json, structure/transports/responses-combo-boundaries.md	Tests cover SSE framing, retry decisions, and response commitment. Documentation describes the preflight boundary and stream lifecycle.

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant Ingress as Claude Messages ingress
  participant Combo as executeComboResponses
  participant Executor as Native Messages executor
  participant Upstream as Anthropic upstream
  participant Preflight as Native Messages preflight
  Ingress->>Combo: Pass eligible Messages source
  Combo->>Executor: Dispatch selected native child
  Executor->>Upstream: Send native Messages request
  Upstream-->>Executor: Return Messages response
  Executor->>Preflight: Inspect response stream
  Preflight-->>Executor: Return failure or accepted stream

Loading

Possibly related issues

• lidge-jun/opencodex#7965: Candidate selection excludes translated Messages children that would drop native-only tools. The requested distinct exhausted-combo diagnostic remains separate work.

Possibly related PRs

• lidge-jun/opencodex#8043: Both PRs add native Messages dispatch for Anthropic combo children and reuse the native executor. This PR limits native children to canonical Anthropic endpoints and adds bounded pre-output fallback and a native-only-tool fence.
• lidge-jun/opencodex#8153: Both changes involve native Messages error handling and combo fallback classification. The error evidence passed between executor and combo is a direct code-level connection.
• lidge-jun/opencodex#8146: The native Messages SSE error filtering and framing changes affect the stream input inspected by the preflight added here.

Merge Risk: Low · previous review 863dc

Eligible no-effort requests to some Anthropic children still use the translated path, so their cache behavior may differ from native replay. This is a bounded limitation to accept or address before merging.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 68.75% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documenta…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title identifies the main change: replaying native Messages for eligible Anthropic children in failover combos. The change aims to preserve prompt-cache breakpoints.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 68.75% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 16 functions across 11 files. (1 skipped: 1 unsupported.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

Finishing Touches

Generate unit tests (beta)

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• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

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[Ingwannu]

Scoped intake at b9d5a543e6e19e3b6b1244cd10396610dd5c0f68; linked the design request #7350. Reusing the existing native Messages executor is preferable to duplicating the fork replay pipeline, but this changes native authentication/usage ownership and pre-output replay decisions across combo children. Keep the strict failover/no-effort/canonical-destination exclusions explicit, along with source-byte capture before rewrites, per-child charging, cancellation usage and exactly-once parent-lease settlement. A native-only tool must not silently become portable on a translated fallback. The described tests/cache-prefix equality are fixtures, not a measured live cache-hit rate. Keep Draft for owner boundary/design review and current-head functional CI; pending fork workflows are not passing evidence. No sponsorship, live provider call, source replay, or merge approval is recorded by this intake.

[vadymhimself]

Thanks for the intake. On the native-only tool point: 5c149b4 makes every translated combo child unpickable when the source declares a tool the translated body drops with no out-of-body lane (bash_*, text_editor_*, ...), under any unrepresentable policy, so a refused native child surfaces its own failure instead of continuing without the tool. web_search/web_fetch stay portable, and non-combo translated routes are unchanged.

Evidence: new cases in tests/claude-integration/messages-native-combo.test.ts (native-only bash tool never fall back to a translated child, portable web_search tool may fall back). With the pick predicate change reverted the native-only case fails (16 pass / 1 fail); with it, 17 pass / 0 fail. tsc --noEmit, structure:check, test-layout, structure-ssot and core-lab-boundary pass. Still draft; the fixtures prove preserved request bytes and fallback decisions, not a live cache-hit rate.

🤖 Generated with Claude Code

[Ingwannu]

Follow-up intake at 8e6fc28a0772ba64a7d0e775036b1e8f6337b6ce against dev 12025981e5a304cdb6b1b54f525ba8554f623977. The added native-only tool pick fence addresses the earlier unsupported-tool fallback concern: a source tool without a translated out-of-body lane must not disappear merely because the first native child refused, while portable hosted search may fall back. Current hosted CI is successful. Keep Draft for the combined native-auth/lease and zero-output replay boundary review: shared spend permit, child-owned cancellation/cleanup, malformed or unknown events committing conservatively, explicit retention and native-only tool refusal must remain authoritative. The author's before/after loopback receipt is useful evidence; I have not independently executed this entire native Messages branch or a live OAuth request.

[vadymhimself]

@lidge-jun requesting a priority bump on this one (P1 suggested — I can't set labels from a fork).

Retitled to reflect the impact: this is a usage leak, not a feature. Today every Claude Code request routed through a strict-failover combo whose first child is Anthropic is translated before it reaches Anthropic, so the prompt-cache prefix never matches and every turn is billed as uncached input. Anyone running Claude Code behind a combo is paying full input price on turns that should be cache reads, continuously, until this lands.

Status: Ingwannu's intake confirmed the native-only tool fence resolved the earlier concern and hosted CI is green at 8e6fc28a0; the branch merges cleanly with current dev. The remaining item is the owner design review of the native-auth/lease and zero-output replay boundary. Happy to split or adjust anything that makes that review faster.

[lidge-jun]

Triage note (2026-10-24, against dev at 2494848).

Needs fixes before this can land: put the new test mapping in a shard, preserve fixture registration, reconcile shared native-transport changes, resolve the author-reported CLI readiness regression, and obtain current-head CI/security review.

Still needed on dev: yes. The existing combo protocol-source interface accepts only Chat (src/server/responses/core-combo-native.ts:73); open issue #7350 requests this Messages capability.

Exact-head CI at triage time: 0ac718d pending approval — metadata checks pass; Cross-platform CI, Catalog async contracts, and React Doctor are action_required. lane=all on exact head: n.a.

Please refresh onto current dev when addressing these; heads older than dev need a fresh exact-head CI run before review.

[vadymhimself]

Thanks for the triage. Addressed at d74a77662, rebased onto dev bd5c2ea90:

• Test mapping in a shard: messages-native-combo.test.ts moved out of layout.json into layout-replay.json, so layout.json gains no line.
• Fixture registration: the tests/fixtures/test-layout-expected.json entry is kept unchanged; layout and tooling guards pass.
• Shared native-transport changes: the branch changes tapAnthropicSseForLog, which the direct passthrough and the managed lane share. An upstream error event now logs its mapped status with terminalStatus: "failed" instead of 200, and both client-cancel paths record the usage seen before the cancel. structure/clients/claude-desktop.md previously documented the 200 and is updated. Two direct-lane cases in claude-native-passthrough.test.ts pin the new contract: they fail on clean dev (71 pass / 2 fail) and pass here.
• CLI readiness: the cli-connect-readiness case fails identically on a clean upstream/dev worktree under the pinned Bun 1.4.3 (26 pass / 1 fail). It reproduces on dev without this branch, and the branch touches no CLI file, so it is not a regression from this PR. I've corrected the PR body, which had described it as an open item.
• Current-head CI and security review: these need a maintainer to approve the workflows for the new head.

Focused suites under Bun 1.4.3 pass (472 / 0), as do tsc, structure:check and privacy:scan. The PR stays in draft until the CI and security review are done.

🤖 Generated with Claude Code

[vadymhimself]

Live evidence for the cache leak, measured today against real Anthropic (Sonnet 5, OAuth, isolated OPENCODEX_HOME, fresh port). Same 6-turn request sequence sent to three servers:

• upstream dev 736fa5087, combo/waterfall (Anthropic child first) → legacy-bridge
• this PR e036ed9e3, combo/waterfall → native
• upstream dev, direct anthropic/claude-sonnet-5 → native (control)

Request shape mirrors Claude Code: 3 system blocks, the middle one carries cache_control: ephemeral, the last one is a small volatile env block (date / git status) that changes every turn; the latest user turn carries cache_control.

turn	dev combo read / write	PR combo read / write	direct read / write
1	0 / 12,370	0 / 12,368	0 / 12,368
2	0 / 13,054	11,638 / 1,414	11,638 / 1,414
3	0 / 13,738	11,638 / 2,098	11,638 / 2,098
4	0 / 14,422	11,638 / 2,782	11,638 / 2,782
5	0 / 15,106	11,638 / 3,466	11,638 / 3,466
6	0 / 15,790	11,638 / 4,150	11,638 / 4,150

On dev, the translated combo lane never reads the cache: the bridge folds the system blocks into one string and moves the breakpoint onto a block that contains the volatile tail, so every turn re-writes the entire prompt at cache-write price. With this PR the combo child replays the caller's bytes and its usage is identical to the direct native route, token for token.

Repro script (bun volatile-repro.ts <label> <model> 6 against a proxy on :10299):

// Reconstructs the 08-29 leak repro: 3 system blocks, last one volatile per turn, cache_control on middle block + last user turn.
const [label, model, turns = "6"] = process.argv.slice(2);
const filler = (tag: string, n: number) => Array.from({ length: n }, (_, i) => `${tag} rule ${i}: keep answers terse and exact; never invent facts; cite files by path.`).join("\n");
const stableA = "You are a coding assistant.\n" + filler("core", 150);
const stableB = filler("project", 250);
const messages: any[] = [];
for (let t = 1; t <= Number(turns); t++) {
  const system = [
    { type: "text", text: stableA },
    { type: "text", text: stableB, cache_control: { type: "ephemeral" } },
    { type: "text", text: `<env>cwd: /work/${label}\ndate: ${new Date().toISOString()}\ngit status: ${t} modified files\nturn: ${t}</env>` },
  ];
  messages.forEach(m => m.content.forEach((b: any) => delete b.cache_control));
  messages.push({ role: "user", content: [{ type: "text", text: `Turn ${t}: reply with exactly the word ok${t}. ` + filler(`ctx${t}`, 20), cache_control: { type: "ephemeral" } }] });
  const res = await fetch("http://127.0.0.1:10299/v1/messages", { method: "POST", headers: { "content-type": "application/json", "x-api-key": "local-test", "anthropic-version": "2023-06-01" },
    body: JSON.stringify({ model, max_tokens: 20, system, messages }) });
  const d: any = await res.json();
  if (!res.ok) { console.log(label, t, res.status, JSON.stringify(d).slice(0, 300)); process.exit(1); }
  const u = d.usage; const total = u.input_tokens + u.cache_read_input_tokens + u.cache_creation_input_tokens;
  console.log(`${label} t${t} read=${u.cache_read_input_tokens} write=${u.cache_creation_input_tokens} uncached=${u.input_tokens} read_share=${(u.cache_read_input_tokens / total * 100).toFixed(1)}%`);
  messages.push({ role: "assistant", content: d.content.filter((b: any) => b.type === "text").map((b: any) => ({ type: "text", text: b.text })) });
}

[lidge-jun]

Maintainer triage (2026-10-28, against dev e1976da):

Native Messages combo replay is still needed. The native-only-tool fence in 803053720 and the sharded test registration/shared-transport regressions in e036ed9e3 address the earlier concrete requests.

Please:

1. Refresh onto dev and reconcile src/server/responses/core-combo.ts around dev lines 400–408, preserving the admission-scope propagation introduced by fix(advisor): preserve captured caller admission scope #7718 alongside the Messages protocol source.
2. Retain scripts/test-layout/layout-replay.json:5 and the matching expected-fixture entry. Keep the affected structure documents within their existing caps.
3. Refresh the focused native Messages, native Chat combo, required-tool and admission-scope regressions through the repository runner with Bun 1.4.4. Update the CLI baseline comparison if it is still cited; a baseline failure does not require an unrelated CLI repair in this PR.
4. Update the readiness attestations for the resulting head and retain Draft pending the requested boundary review.

The earlier native-only-tool and test-layout requests are not being reopened. A maintainer will then authorize current-head PR CI and complete the native-authentication, lease, cancellation and replay review. Historical CI and author-provided live measurements remain separate from that acceptance.

[vadymhimself]

@lidge-jun the live repro above shows the translated combo lane still gets a 0% cache read on current dev (736fa5087), with every turn re-written at cache-write price, while this PR matches the direct native route token for token. Could you approve the pending Cross-platform CI / Catalog async contracts runs and take a look? I'll rebase onto the current dev tip right away if that helps review.

[coderabbitai]

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Review info

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• Source mode: Auto
• Repository: lidge-jun/opencodex
• Branch: dev
• File: .coderabbit.yaml
• Commit: 3dc4060
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Commits

Reviewing files that changed from the base of the PR and between 3df2b15 and 863dc3e.

Files selected for processing: 4

• src/claude/inbound-content-options.ts
• src/server/responses/core-combo-native.ts
• structure/data-planes/protocol-paths.md
• tests/claude-integration/messages-native-combo.test.ts

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 8 remain after this review.

[lidge-jun]

The folded SSE error return can lose the preflight commitment. In src/server/messages-native.ts:1058, an accepted preflight sets committed = true, but the collectedErrorEvent path at line 1109 returns a 502 directly, without the non-replayable marker applied by fail and failEvidence. For a non-streaming caller whose native child receives an empty event:error, or an error payload without type: "error", followed by message_stop before content, preflight commits conservatively while the collector produces this unmarked error. The combo can then send the same request to a backup target after commitment, adding inference and spend. A controlled source-level probe reproduced the missing marker; a live upstream occurrence has not been established. Please mark the committed collector-error response non-replayable and add combo integration coverage proving no backup send for these cases.

[lidge-jun]

I found three additional issues on 863dc3e:

1. Existing combo exhaustion tests fail. tests/responses/responses-combo-exhausted-error.test.ts:218 still expects two retained copies when eligibility now makes one; both cooldown variants fail. The case at line 234 expects a thrown eligibility check and a 401, but now gets 503 because the second-copy exception is no longer exercised. I ran bun scripts/test.ts tests/responses/responses-combo-exhausted-error.test.ts: 24 passed and 3 failed. Please update the assertions and explicitly inject an eligibility exception to preserve that coverage.

2. Cancellation loses observed usage. src/server/messages-native.ts:1011 binds logCtx.usage, but the tap's abort and reader-cancel paths at src/server/messages-shared.ts:315 and :460 finalize without publishing their accumulated usage. A controlled probe with message_start usage followed by content and cancellation finalized 499 with undefined usage. Please publish observed usage before cancellation finalization and assert it in the combo cancellation regression.

3. A streamed error after content is recorded as completed. src/server/messages-shared.ts:359-369 can finalize a delivered error terminal with status 200; src/server/responses/core-combo-native.ts:433 passes that to callbacks which treat status below 400 as completed. A controlled stream of message start, content, then an overloaded error reaches the completed callbacks. Please preserve the no-replay decision while recording a failed terminal, and assert the terminal status in the existing commitment tests.

[lidge-jun]

Two issues remain on head e73d594:

1. Malformed folded SSE errors can still lose the non-replayable commitment. src/server/messages-native-preflight.ts:35-40 commits on a malformed event: error payload, and src/claude/outbound.ts:1284-1287 records the error event before skipping malformed data. For a non-streaming caller with an empty message_start, malformed error and then message_stop, src/server/messages-native.ts:1118-1128 can return an unmarked 502 even though the preflight committed. With no content output, the outer output-based guard does not mark it, so a combo may send another inference. Please mark that committed collector-error response non-replayable and cover malformed payloads end-to-end. This is a static control-flow finding; a runtime reproduction has not yet been run.

2. Observe-only native Messages can double-count a prepaid workflow send. src/server/messages-native.ts:670 calls reportDispatchSends without indicating that spendReport.beforeSend has already claimed the workflow start. src/lib/request-execution-budget.ts:340 can then record the prepaid start again, exhausting a two-send root after one physical send. Please preserve the already-counted flag as the native Chat path does and add an observe-only workflow counter regression. This finding is also based on static tracing; runtime verification remains needed.

[lidge-jun]

The fresh review found an additional retry-boundary case on e73d594: src/server/messages-native.ts:1053-1057 returns an unmarked 502 when preflight retention exceeds the translator budget. If the tap already observed a content frame before the budget failure, the combo may replay the request to a fallback despite output having been observed. A controlled exact-source probe reproduced generationObserved: true with a replayable response and a fallback dispatch. Please preserve the non-replayable commitment for this failure and cover it through the real combo path.

The fresh technical review also reproduced the cancellation-usage and streamed-error terminal findings from my earlier review on this updated head. The malformed folded-error and observe-only double-count cases are covered in the separate comment on this head.

[lidge-jun]

Maintainer review (independent technical review at head e73d594, also verified on the clean union with dev 05408a3). Thanks for the update — the exhausted-error regression test finding is now closed (24/3 → 27/0) and the file-size ratchet passes on the union. Three earlier findings are still reproducible with independent probes (each fails on 863dc3e, on this head, and on the union):

1. P1 — committed malformed folds still permit replay. src/server/messages-native.ts:1128 returns the collected-error 502 without the non-replayable marker even though the request is committed at line 1077. Malformed-JSON and mismatched payload-type probes both dispatched the backup target and recorded two sends. Please apply the commitment/non-replayable marking on this return path too, with a regression asserting a single send.
2. P2 — cancellation still drops observed usage. src/server/messages-shared.ts:315 and :460 finalize without publishing accumulated usage. Signal-abort and reader-cancel probes produced a 499 row and attempt with usageStatus: "unreported" despite usage frames having been received. Publish usage before cancellation settlement and bind it before final logging.
3. P2 — streamed errors still become successful completions. src/server/responses/core-combo-native.ts:433 maps the tap's terminal 200 into the success callbacks; a post-content overloaded_error produced status 200 / terminalStatus: "completed" in the row and attempt. Carry the actual error verdict before publishing completion.

Keeping this on hold until these are addressed; happy to re-review the next head.

[vadymhimself]

Thanks for the three reviews on e73d594. All five findings are addressed at 68152bdb1 (after merging dev 6df9e1176 with a merge commit). Each regression below fails on 800bafec3 and passes here.

1. P1: committed malformed folds can still replay. When the collector returns its 502 after the request committed, that response is now marked non-replayable (messages-native.ts). Regression: a fold committed by a malformed error event never replays, with one case for bad JSON and one for a type mismatch. Both assert a single send and no backup dispatch.
2. Preflight buffer failure after a content frame. In both preflight catch blocks (streaming and fold), the request now counts as committed when the tap has already recorded generationStartedAt. Regression: a preflight buffer failure after a content frame never replays. It goes through the real combo path, with the retained-collector charge failing on the content chunk.
3. Observe-only double count. onPhysicalDispatch now calls reportDispatchSends(..., true), which is what native Chat does. Regression: an observe-only workflow root counts one native send once uses a root with maxPhysicalSends: 2. The primary and the fallback each send once, and the root records 2 sends. Before the fix, the fallback was refused.
4. P2: cancellation drops usage. The shared tap calls recordUsage() before settling a signal abort or a reader cancel, and the fold binds usage before its 499. Regression: a reader cancel / signal abort keeps the usage already received in messages-shared-sse. The 895a859 goldens (messages-native-stream-parity, messages-sse-*-errors) pin every other fact unchanged. The only new allowance is that the cancel rows now carry the usage they received.
5. P2: streamed errors become completions. The tap now records the mapped status of a terminal upstream error event on logCtx.streamErrorStatus. The native combo child reads it and closes as failed with that status instead of calling the completion callbacks. The direct passthrough row and the tap's finalize contract stay as they are on dev. Regression: a streamed error after content is a failed child, not a completion, which asserts row status 503 and terminalStatus: "failed".

Validation is in the PR body. The full bun run test run fails only in files that also fail on a clean dev worktree. typecheck, structure:check and privacy:scan pass.

[lidge-jun]

One remaining replay-safety finding on this head; keeping the PR on hold.

[lidge-jun]

A separate replay-boundary finding remains on this head; keeping the PR on hold.

[lidge-jun]

P1: Do not replay when output follows a retryable error in the same upstream read. The streaming relay reframes the original upstream chunk before this preflight reads it, and preflight stops as soon as it sees the error. Consequently it can miss a complete or partially received content frame that accompanied that error upstream and send the same turn to a fallback. On this head, end-to-end probes produced two sends for an error followed by a complete content frame in one upstream chunk (streaming), and for an error followed by an incomplete content frame (both streaming and folded); the complete folded case stayed on one send. Preserve sufficient original-read or commitment evidence before deciding to replay, and cover complete and fragmented following frames in both paths.