fix(review): add DeepSeek Zen free reviewer

[seonghobae]

Summary

• add OpenCode Zen DeepSeek V4 Flash Free as the first public-repository reviewer
• keep North Mini Code Free as the public fallback
• keep both free models out of private repositories because their free-period data terms permit retention or improvement use
• require the exact DeepSeek-first order, tool-call support, and absence of forced response formatting in the contract test

Validation

• pytest -q — 674 passed
• pytest -q tests/test_opencode_agent_contract.py — 37 passed
• ruff check tests/test_opencode_agent_contract.py
• workflow YAML parse
• git diff --check

Review evidence

• Probe 1: tests/test_opencode_agent_contract.py:94-121 asserts the public-only expression and exact DeepSeek-then-North order.
• Probe 2: tests/test_opencode_agent_contract.py:141-154 parses the generated provider config and asserts both models use tool calls without forced response_format.
• Negative privacy path: .github/workflows/opencode-review-dispatch.yml:3720 includes the free prefix only when is_private == false.

Closes #648

[coderabbitai]

📝 Walkthrough

Walkthrough

OpenCode 무료 모델 카탈로그에 DeepSeek V4 Flash Free를 추가하고, 공개 저장소에서 두 무료 모델을 후보로 선택하도록 변경했다. 관련 워크플로 및 생성 설정 검증 테스트도 후보 조합에 맞게 확장했다.

Changes

OpenCode 무료 모델 라우팅

Layer / File(s)	Summary
무료 모델 카탈로그 및 후보 라우팅 .github/workflows/opencode-review-dispatch.yml	deepseek-v4-flash-free의 식별자, tool call, context/output limit을 추가하고, 공개 저장소에서 DeepSeek 및 North 무료 모델을 후보로 사용하도록 조건을 변경했다.
모델 후보 및 설정 계약 테스트 tests/test_opencode_agent_contract.py	후보 조합별 검증을 지원하고, 두 무료 모델의 tool_call 활성화 및 response_format 부재를 생성된 설정에서 확인하도록 테스트를 갱신했다.

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

Possibly related PRs

• ContextualWisdomLab/.github#646: is_private에 따른 OpenCode 무료 모델 후보 라우팅과 관련 테스트를 함께 변경한다.
• ContextualWisdomLab/.github#649: deepseek-v4-flash-free 후보 및 생성 설정 검증을 추가한다.
• ContextualWisdomLab/.github#653: OpenCode 무료 모델 카탈로그와 tool_call 테스트를 갱신한다.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	DeepSeek free 리뷰어 추가와 관련된 모델 카탈로그 및 계약 테스트 변경을 잘 요약한 제목입니다.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch test/opencode-zen-free-rollout

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_{Comment @coderabbitai help to get the list of available commands.}

[seonghobae]

Controlled bootstrap merge audit:

• Exact PR head: 471fae2d056a53c8c91754dcfbb60f41aa55c89a; squash merge: dd1ae2585cb91ca4f57433906449c62ea585cace.
• Reason: base-branch OpenCode run 30488270555 exhausted the old pool after North returned invalid control output; the base workflow could not use this PR’s DeepSeek Zen candidate before the fix reached main.
• Pre-merge evidence: all current-head hosted security/CodeQL/coverage/Strix checks green, no unresolved review threads, no open code-scanning alerts on the PR ref, local full suite 674 passed, focused contract 37 passed.
• Controlled bypass: repository ruleset 17921150 briefly granted only seonghobae pull-request bypass and branch-protection admin enforcement was briefly disabled. Both were restored immediately after the SHA-pinned merge. Post-restore state is active ruleset, empty bypass actors, admin enforcement enabled, two-review/last-push ruleset intact, required statuses intact.
• Post-merge default branch: focused contract 37 passed; full suite including concurrently merged fix(review): materialize base coverage locks by content, not exact filename (org-backlog root cause) #657 677 passed; Ruff/actionlint/YAML/diff checks pass.