Rust-hybrid Phase 6: Rust-owned per-file gap fallback

[jununfly]

This was generated by AI during triage.

What to track

Track Rust-Hybrid Phase 6 implementation for Rust-owned per-file gap fallback.

Plan: docs/plans/2026-06-18-rust-hybrid-phase-6-rust-owned-per-file-gap-fallback.md

Phase 6 closes the PRD gap where the Rust process succeeds but individual Rust-owned files hit parse or extraction gaps. Those files should fall back through the TypeScript append path when, and only when, Rust can guarantee they were not written.

This tracker does not claim final first-user release readiness by itself.

Acceptance criteria

• Rust core per-file failure contract is implemented.
• CLI fake-core per-file fallback append works.
• Status and doctor taxonomy records degraded Rust-owned gap fallback.
• Partial-write blocked taxonomy is recorded when fallback is unsafe.
• One real reduced fixture attempt is recorded.
• Evidence doc is written under docs/benchmarks/.
• Decision doc is written under docs/plans/.
• Decision keeps SDK, README, full packaged smoke, replacement cleanup, and Post-PRD optimization tracker for Rust indexing performance #165 out of scope.

Child issues

To be linked after creation.

[jununfly]

This was generated by AI during triage.

Phase 6 issue sequence

Execute in this dependency order:

1. Rust-hybrid Phase 6.1: Add Rust core per-file failure contract #261 - Rust core per-file failure contract.
2. Rust-hybrid Phase 6.2: Append TypeScript fallback for Rust-owned per-file gaps #258 - CLI per-file fallback append, blocked by Rust-hybrid Phase 6.1: Add Rust core per-file failure contract #261.
3. Rust-hybrid Phase 6.3: Record Rust-owned gap taxonomy in status and doctor #259 - Status and doctor taxonomy, blocked by Rust-hybrid Phase 6.2: Append TypeScript fallback for Rust-owned per-file gaps #258.
4. Rust-hybrid Phase 6.4: Attempt real reduced Rust-owned gap fixture smoke #260 - Real reduced fixture smoke attempt, blocked by Rust-hybrid Phase 6.3: Record Rust-owned gap taxonomy in status and doctor #259.
5. Rust-hybrid Phase 6.5: Record per-file fallback evidence and decision #262 - Evidence and decision, blocked by Rust-hybrid Phase 6.4: Attempt real reduced Rust-owned gap fixture smoke #260.

Plan file:

docs/plans/2026-06-18-rust-hybrid-phase-6-rust-owned-per-file-gap-fallback.md

[jununfly]

This was generated by AI during triage.

Phase 6 tracker completed.

Closed child issues:

• Rust-hybrid Phase 6.1: Add Rust core per-file failure contract #261 Rust core per-file failure contract.
• Rust-hybrid Phase 6.2: Append TypeScript fallback for Rust-owned per-file gaps #258 CLI per-file fallback append.
• Rust-hybrid Phase 6.3: Record Rust-owned gap taxonomy in status and doctor #259 Status and doctor taxonomy.
• Rust-hybrid Phase 6.4: Attempt real reduced Rust-owned gap fixture smoke #260 Real reduced fixture smoke attempt.
• Rust-hybrid Phase 6.5: Record per-file fallback evidence and decision #262 Evidence and decision.

Verification:

• npm run build
• npx vitest run __tests__/rust-index-engine-cli.test.ts __tests__/rust-hybrid-doctor.test.ts
• cargo test --package zcodegraph-core emits_structured_rust_owned_parse_gap_errors

Decision: docs/plans/2026-06-18-rust-hybrid-phase-6-decision.md

Evidence: docs/benchmarks/2026-06-18-rust-hybrid-phase-6-per-file-gap-fallback-evidence.md