fix(deepseek): normalize tool result adjacency

[Ingwannu]

Summary

• Normalize unambiguous DeepSeek Responses tool-call continuations so each result immediately follows its matching call.
• Preserve hook-injected developer content by moving it after the matched result instead of dropping it.
• Gate the behavior behind provider capability metadata so tolerant Responses providers keep their original history order.
• Backfill the DeepSeek capability into stale provider configurations and document the provider-specific decision boundary.

Verification

• taskset -c 0-1 bun run typecheck — passed on the rebased exact head.
• taskset -c 0-1 bun test tests/deepseek-inbound-wire.test.ts tests/openai-responses-passthrough.test.ts tests/deepseek-reasoning-replay.test.ts tests/deepseek-reasoning-replay-gaps.test.ts tests/config.test.ts tests/provider-registry-parity.test.ts tests/config-save-boundary.test.ts — 277 passed, 0 failed on the rebased exact head.
• Full pre-rebase suite — 10,166 passed, 10 skipped, 2 unrelated local-environment failures:
  • the existing Codex shim token-file test resolves the live OpenCodex token path in this running proxy environment and also fails in isolation;
  • the npm cache worker test exceeded its 5-second bound during the 828-second CPU-limited suite, then passed 11/11 in 1.1 seconds when rerun alone.
• git diff --check origin/dev...HEAD — passed.

Decision Log

• 목적과 의도: Make valid Codex tool continuations acceptable to DeepSeek when hook context is persisted between a call and its result.
• 기존 구현 및 제약 조건: Existing orphan repair checks pair presence only; globally changing valid history would affect tolerant providers and moving or dropping the developer message is semantically meaningful.
• 검토한 주요 대안: Reorder all Responses providers, drop the injected message, or add a provider capability and perform a lossless one-to-one reorder.
• 선택한 방식: Enable adjacency normalization only for DeepSeek, move only unique matched pairs, and preserve every intervening item after the result.
• 다른 대안 대신 이 방식을 선택한 이유: This fixes the confirmed strict parser without changing tolerant provider history or guessing across duplicate call ids.
• 장점, 단점 및 영향: DeepSeek accepts the continuation and no context is lost; the relative position of intervening context moves after the tool result only on the declared strict provider.

Checklist

• Scope stays focused and avoids unrelated cleanup.
• Docs or release notes were updated when needed. The provider contract, type documentation, and in-code Decision Log are updated; no user command or configuration workflow changes.
• Security-sensitive changes were reviewed for secrets, auth, and unsafe defaults. No credential destination or authentication path changes.

Closes #1292

Summary by CodeRabbit

• Bug Fixes
  • Improved compatibility with providers that require tool results to immediately follow their corresponding tool calls.
  • Automatically preserves message order when tool-call matches are ambiguous or when providers do not require adjacent results.
  • Enabled this behavior for DeepSeek while preserving intervening developer context.

[coderabbitai]

📝 Walkthrough

Walkthrough

The change adds provider-aware Responses history normalization. Enabled providers move uniquely matched tool results directly after their calls. DeepSeek enables the capability, while explicit provider settings remain authoritative.

Changes

Responses tool-result adjacency

Layer / File(s)	Summary
Provider capability and configuration flow src/types.ts, src/config.ts, src/providers/registry.ts, src/providers/derive.ts, src/router.ts	Adds the optional requiresAdjacentResponsesToolResults capability, enables it for DeepSeek, and propagates it through provider seed, backfill, and routing paths without overriding explicit values.
Responses request normalization src/adapters/openai-responses.ts	Indexes function, shell, and custom tool calls and outputs. When enabled, request construction moves only uniquely matched non-adjacent outputs directly after their calls.
DeepSeek capability and ordering tests tests/deepseek-inbound-wire.test.ts	Tests registry propagation, DeepSeek reordering with preserved developer context, and unchanged interleaved history for providers without the capability.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant ProviderRegistry
  participant Router
  participant OpenAIResponsesAdapter
  participant DeepSeek
  ProviderRegistry->>Router: provide adjacency capability
  Router->>OpenAIResponsesAdapter: construct provider configuration
  OpenAIResponsesAdapter->>OpenAIResponsesAdapter: normalize unique tool call/result pairs
  OpenAIResponsesAdapter->>DeepSeek: send reordered Responses input

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Possibly related PRs

• lidge-jun/opencodex#302: Modifies Responses tool-result handling that the adjacency normalization must preserve.
• lidge-jun/opencodex#360: Also changes request preprocessing in src/adapters/openai-responses.ts.
• lidge-jun/opencodex#934: Also normalizes DeepSeek-related Responses history in src/adapters/openai-responses.ts.

Suggested labels: review-ready

Suggested reviewers: lidge-jun, wibias

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The changes address issue #1292 by conditionally moving matching tool results next to calls while preserving intervening developer content.
Out of Scope Changes check	✅ Passed	The provider capability plumbing, DeepSeek registry configuration, normalization logic, and tests all support the linked issue objectives.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: normalizing DeepSeek tool result adjacency.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch agent/fix-1292-deepseek-tool-order

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[github-actions]

✅ Deterministic PR hygiene checks passed.

[lidge-jun]

Landed on dev as 56cca2f, rebased onto the current head with your authorship preserved.

Verified before merge: src/adapters/openai-responses.ts:507-535 only checked functionCallIds.has(callId) and preserved original ordering, with no adjacency normalization in the forwarding pipeline at :1158-1160 — so developer context between a tool call and its result really did break DeepSeek continuations. Gating the normalization on the provider capability and moving only uniquely matched pairs is the right conservative shape: tolerant providers are untouched and intervening content survives. Full suite green (10243 pass, 0 fail).

Thanks — the stale-config backfill and the tolerant-provider control test are what make the capability plumbing convincing rather than just plausible.