fix(observability): surface RAG/enrichment/inline review failures to Sentry (#1618)

[JSONbored]

Summary

Three review-pipeline failure points were caught + swallowed and never reached Sentry (the central forwarder captures level:error/fatal structured logs). When the reviewer's context backends degrade, the review silently gets worse with no signal — exactly the diagnosis pain behind the recent self-host outage. This surfaces them at error (no forwarder change needed; each remains fail-safe — only visibility changes):

• RAG retrieval (retrieveContext, rag.ts) — logged rag_retrieve_error via console.log with no level field → a down qdrant/embedder degraded reviews to diff-only, invisibly. Now level:error review_context_fetch_failed (contextType:rag), keeping the ev tag for log continuity.
• REES enrichment (buildReviewEnrichment catch) — swallowed fetch/timeout/parse errors. Now level:error review_context_fetch_failed (contextType:enrichment).
• Inline review comments (postInlineReviewComments catch) — logged the post failure at warn (forwarder skips it). Now error.

Each fix is exercised by a regression test asserting it surfaces at level:error. Grounding-wire and rag-wire's outer catches are intentionally left as-is — their inner code is fail-safe so those catches are unreachable; the real RAG failure point is inside retrieveContext, which is where the fix lands.

Closes #1618.

Scope

• The PR title follows type(scope): short summary Conventional Commit format.
• This PR is focused — observability only (review-context failure surfacing); no behavior change.
• This follows CONTRIBUTING.md; no site/, CNAME, or Pages.
• I linked an issue.

Validation

• git diff --check
• npm run actionlint
• npm run typecheck
• npm run test:coverage locally; codecov/patch ≥97% — each changed catch is exercised by a test asserting the level:error review_context_fetch_failed / inline_comments_post_failed log (rag via a throwing vector query, enrichment via a rejecting fetch, inline via a 500 review POST).
• npm run test:workers
• npm run build:mcp
• npm run test:mcp-pack
• npm run ui:openapi:check
• npm run ui:lint
• npm run ui:typecheck
• npm run ui:build
• npm audit --audit-level=moderate
• Regression tests for each new error-surfacing path

If any required check was skipped, explain why:

• No artifact regeneration / migration: pure logging-level change, no API/schema/binding/DB change.

Safety

• No secrets/wallets/hotkeys/trust-scores/private rankings exposed — the logs carry repo/PR/contextType + a bounded error message (the error strings are infra failures, not PR content; the existing redaction/.slice bounds apply).
• Public GitHub text stays sanitized — these are server logs, not GitHub surfaces.
• Auth/CORS/session changes include negative-path tests — N/A.
• API/OpenAPI/MCP behavior updated/tested — N/A.
• UI changes use live data — N/A (no UI change).
• Visible UI changes include UI Evidence — N/A.
• Public docs/changelogs updated — N/A.

Notes

• This completes the review-pipeline Sentry coverage: provider exhaustion (fix(observability): capture AI-CLI stderr + surface exhausted provider failures to Sentry #1605), precise CLI error status (fix(selfhost): surface the CLI's structured stdout error before the exit code (#1612) #1613), and now RAG/enrichment/inline failures — every failure point in the review path now reaches Sentry at error.

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@0700d3c). Learn more about missing BASE report.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1619   +/-   ##
=======================================
  Coverage        ?   95.51%           
=======================================
  Files           ?      204           
  Lines           ?    22051           
  Branches        ?     7966           
=======================================
  Hits            ?    21062           
  Misses          ?      413           
  Partials        ?      576           

Files with missing lines	Coverage Δ
src/review/enrichment-wire.ts	100.00% <100.00%> (ø)
src/review/inline-comments.ts	100.00% <100.00%> (ø)
src/review/rag.ts	100.00% <100.00%> (ø)

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