fix(providers): replay DeepSeek reasoning for opencode-zen (#994)

[justjxke]

Summary

• opencode-zen was the only OpenCode provider missing DeepSeek reasoning metadata. The fix(responses): keep DeepSeek reasoning_content on tool-call continuations (#950) #971 replay fix only fires for models in preserveReasoningContentModels, and opencode-zen declared none — so opencode-zen/deepseek-v4-flash-free tool-call continuations went upstream without the original reasoning_content, and the gateway rejected them with HTTP 400.
• Mirrors the DeepSeek thinking metadata (preserveReasoningContentModels, reasoning-effort map, noVisionModels) that opencode-go and opencode-free already carry onto opencode-zen, covering deepseek-v4-pro, deepseek-v4-flash, and deepseek-v4-flash-free.

Closes #994

Verification

• bun run typecheck — pass
• bun test tests/opencode-zen-deepseek-reasoning.test.ts — pass (regression; red before fix, green after; also asserts effort mapping and that non-listed models are untouched)
• bun test tests/provider-registry-parity.test.ts tests/opencode-go-deepseek.test.ts tests/reasoning-effort.test.ts tests/deepseek-reasoning-replay.test.ts — pass
• bun run test — 9018 pass, 0 fail
• bun run 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.

Related

• #950 — original report: intermittent drop of reasoning_content on tool-call continuation for DeepSeek thinking mode
• #971 — the replay fix that covered opencode-go / opencode-free but not opencode-zen
• #994 — regression this PR closes (same 400 via opencode-zen)

Review readiness checklist

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

• All CI tests are green on my local testing.

• I pushed my PR to the latest dev commit.

• I fixed all correct Codex and CodeRabbit findings.

• My PR is ready for review.

Summary by CodeRabbit

• New Features

  • Added OpenCode Zen DeepSeek model support with configurable reasoning levels, including xhigh mapped to the maximum level.
  • Preserved reasoning content across tool-call continuations for more consistent multi-step responses.

• Bug Fixes

  • Improved tool-call handling for DeepSeek conversations.
  • Correctly identifies DeepSeek models as lacking native image understanding.

[github-actions]

Review readiness checklist

This PR is kept in draft until every requirement below is fulfilled. The tickable checklist has been added to your PR description — tick all four boxes there.

• ✅ All CI tests are green on my local testing.
• ✅ I pushed my PR to the latest dev commit.
• ✅ I fixed all correct Codex and CodeRabbit findings.
• ✅ My PR is ready for review.

✅ 4/4 boxes ticked.

✅ All four boxes are ticked.
Completed against head f377088; new commits after this will reset the checklist.
This pull request is already Ready for Review.
Maintainers: @lidge-jun @Ingwannu @Wibias

[github-actions]

✅ Deterministic PR hygiene checks passed.

[coderabbitai]

📝 Walkthrough

Walkthrough

The opencode-zen registry now configures reasoning behavior and vision routing for DeepSeek models. Integration tests verify effort mapping, reasoning replay during tool-call continuations, tool-call serialization, and non-DeepSeek behavior.

Changes

OpenCode Zen DeepSeek reasoning support

Layer / File(s)	Summary
DeepSeek registry metadata and adapter validation src/providers/registry.ts, tests/opencode-zen-deepseek-reasoning.test.ts	The registry adds reasoning-effort mappings, preserves reasoning_content during continuations, and marks listed DeepSeek models as lacking native vision support. Tests validate xhigh to max mapping, replayed reasoning content, serialized tool calls, and non-DeepSeek routing.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• lidge-jun/opencodex#906: Implements related DeepSeek reasoning replay behavior.
• lidge-jun/opencodex#971: Adds related OpenCode Zen reasoning_content preservation configuration.
• lidge-jun/opencodex#1069: Updates related DeepSeek reasoning effort mappings and tests.

Suggested reviewers: wibias, ingwannu, lidge-jun

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The registry changes preserve DeepSeek reasoning content and the tests cover continuation replay, addressing issue #994.
Out of Scope Changes check	✅ Passed	The changes are limited to opencode-zen DeepSeek metadata and regression tests related to issue #994.
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 identifies the provider fix and the DeepSeek reasoning replay change described in the pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@tests/opencode-zen-deepseek-reasoning.test.ts`:
- Around line 75-80: Add focused image-request regression coverage near the
existing tests in tests/opencode-zen-deepseek-reasoning.test.ts for
deepseek-v4-pro, deepseek-v4-flash, and deepseek-v4-flash-free. Exercise the
noVisionModels configuration from the provider registry and assert each model
follows its expected no-vision or vision-sidecar path, while preserving the
existing reasoning replay tests.

🪄 Autofix

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 97e90f8b-4585-4bad-8c33-eb36766bf9fa

📥 Commits

Reviewing files that changed from the base of the PR and between 0e92714 and 391bae1.

📒 Files selected for processing (2)

• src/providers/registry.ts
• tests/opencode-zen-deepseek-reasoning.test.ts