[huynle-dev]

Summary

• Claude requests that explicitly ask for readable thinking (thinking: { type: "adaptive", display: "summarized" }, as sent by @ai-sdk/anthropic / OpenCode) came back with empty thinking text plus a signature. Cause: OmniRoute adds the redact-thinking-2026-02-12 beta by itself:

  • selectBetaFlags() pushes it for opaque clients and for any client that negotiated interleaved-thinking-2025-05-14 (which @ai-sdk/anthropic always sends), and
  • the static ANTHROPIC_BETA_API_KEY set used by API-key connections includes it.

  Only CC-compatible relays without the redactThinking opt-in had it stripped (the post-pass in base.ts).

• Fix (new pure leaf open-sse/executors/base/redactThinkingBeta.ts):

  • selectBetaFlags() leaves out redact-thinking-2026-02-12 when the body asks for thinking.display: "summarized".
  • A final dispatch pass (right before stripInternalBodyFields) removes OmniRoute-added redact-thinking-* tokens from anthropic-beta under the same rule, so the static API-key set is covered too.
  • New opt-out OMNIROUTE_REDACT_THINKING=false stops OmniRoute adding the redact beta at all (documented in .env.example + docs/reference/ENVIRONMENT.md).
  • Unchanged: a client that negotiated a redact-thinking beta itself keeps it, and a CC-compatible connection with requestDefaults.redactThinking: true keeps it. Without display: "summarized" (and without the env), current behavior stays the same.

Related Issues

• None filed; found while debugging empty summarized thinking through the native claude (OAuth) provider.

Target Branch

• Base is the active release/v3.8.x branch (release/v3.8.52), not main

Validation

• Change type: provider
• Focused tests: tests/unit/claude-*.test.ts tests/unit/anthropic-*.test.ts tests/unit/executor-*.test.ts tests/unit/cc-compatible*.test.ts tests/unit/provider-request-failure-pipeline.test.ts tests/unit/context-editing-executor-injection.test.ts tests/unit/base-*.test.ts → 2064 tests, 2056 pass, 1 fail (Adapta stream errors are sanitized in an isolated executor fixture, which fails the same way locally without this change).
• New test fails before the fix (4/9 red) and passes after.
• tsc -p tsconfig.typecheck-core.json clean; Prettier clean; check-file-size and check-env-doc-sync OK.
• npm run lint (CI)

Tests Added Or Updated

• tests/unit/claude-5x-thinking-passthrough.test.ts (new, test-only): end-to-end handleChatCore coverage that captures the upstream /v1/messages body. thinking: {type:"adaptive", display:"summarized"} must reach the upstream unchanged for claude-haiku-5-5 / claude-sonnet-5-5 / claude-opus-5-5 on both claude (OAuth) and anthropic (API key). Haiku 4.5 must keep enabled + budget_tokens. A manual budget on Haiku 5.5 must collapse to adaptive. This is regression cover for fix(claude): stop downgrading adaptive thinking on claude-haiku-5-5 #15841: without it, 3.8.51 rewrites Haiku 5.5 to enabled + budget_tokens: 10000, which the API-key path rejects with 400 and the OAuth path answers with empty thinking. Passes on the current release/v3.8.52 tip.

• tests/unit/claude-summarized-thinking-redact-beta.test.ts (new): predicate/env unit tests, selectBetaFlags with and without summarized display, the header strip helper (incl. client and connection opt-in), and end-to-end DefaultExecutor dispatch for claude (OAuth) and anthropic (API key) capturing the outbound anthropic-beta.

• tests/unit/provider-request-failure-pipeline.test.ts (CC-compatible relay with redactThinking: true + summarizeThinking: true still keeps the beta) passes unchanged.

Coverage Notes

• open-sse/executors/base/redactThinkingBeta.ts is fully exercised by the new test; the base.ts / claudeIdentity.ts call sites are covered by the dispatch tests.

Reviewer Notes

• open-sse/executors/base.ts grows by +5 lines (1744 → 1749, cap 2094): one import plus one call at the final dispatch chokepoint.
• Risk: requests that ask for summarized thinking no longer send redact-thinking-2026-02-12. That is the behavior the client asked for; set requestDefaults.redactThinking on a CC-compatible connection, or send the beta from the client, to keep redaction.

[diegosouzapw]

Thank you @huynle-dev — this landed as #17040. Your branch is in an organization-owned fork, where GitHub does not let maintainers push even with "allow edits by maintainers" on (403), so your three commits were carried into #17040 unchanged and you are credited with a Co-authored-by trailer on the squash commit. On top of them, dropping the redact-thinking beta for Claude OAuth requests now sits behind a default-off flag (CLAUDE_OAUTH_SUMMARIZED_THINKING_UNREDACTED), because that beta is part of the Claude Code OAuth fingerprint; API-key requests get your fix by default. Closing this one as merged via #17040. (/merge-batch 2026-10-17)