release: migrate legacy Qwen sidecars to Jina

[justrach]

Summary

• recognize only the exact legacy hosted-Qwen 512D sidecar
• serve the triggering hybrid request through bounded exact Jina reranking,
  then schedule one background rebuild
• keep the old OpenPuffer generation until the Jina replacement validates and
  commits atomically
• join the migration worker before project-cache eviction or shutdown
• preserve custom-provider, Windows, sensitive-path, and no-CPU-fallback
  boundaries
• document the opt-out: CODEDB_NO_AUTO_SEMANTIC_MIGRATION=1
• bump release metadata to 0.2.5852

Verification

• zig build test
• zig build test-ann
• zig build test-semantic-index
• vendored OpenPuffer zig build test (recall@10 = 1.000)
• MCP E2E: 76/76
• ReleaseFast cross-builds: macOS x86_64, Linux x86_64/aarch64, Windows x86_64
• production-backed smoke: legacy Qwen sidecar → first exact Jina result →
  1.52s background rebuild → next query ann_applied through mmap OpenPuffer

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-01T04:49:34.400146Z	b72db9b	PR opened

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[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: b72db9bcf6

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[chatgpt-codex-connector]

Disclose automatic migration in the MCP tool schema

When a hybrid MCP query encounters a legacy Qwen sidecar, this call now starts a repository-wide background embedding build, but the codedb_context schema at src/mcp.zig:701 still says the ANN is explicitly built and that a missing or stale sidecar only sends bounded reranking candidates. Clients relying on tools/list therefore are not informed that an ordinary query can transmit all indexable code chunks; update the tool description to disclose the narrow migration and opt-out.

AGENTS.md reference: AGENTS.md:L5-L12

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[chatgpt-codex-connector]

Preserve fallback failures when reporting migration status

If exact Jina reranking fails for a legacy sidecar, the handler first records the provider error at lines 4442-4444, but a successfully scheduled migration overwrites that diagnostic here while leaving retrieval.semantic as unavailable. The structured response then reports only AnnSidecarMigrationScheduled, hiding the reason retrieval failed; migration status needs a separate field or must not replace the failure detail.

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