Phase 4: make Rust indexing RSS and profile evidence repeatable

[jununfly]

This was generated by AI during triage.

What to build

Make Phase 4 Rust indexing profile evidence repeatable enough to support rollout-readiness decisions. The profiler or validation harness should compare TypeScript and Rust indexing on the hard-gate repositories and report wall-clock, peak RSS, finalization subphases, toolchain metadata, and explicit RSS unavailable reasons.

Acceptance criteria

• TypeScript and Rust profile output includes wall-clock time, peak RSS, source scanning, parsing/extraction, SQLite writing, subprocess handoff, and TypeScript finalization subphases.
• RSS output is valid on at least one supported platform, and unavailable RSS includes a machine-readable reason rather than an unexplained null.
• Profile artifacts include repository commit, indexed file count, CLI version, Rust core version, Node version, OS, and architecture.
• Baseline profiles are recorded for ZCodeGraph, Excalidraw, and Zustand.
• Automated tests cover profile JSON shape, RSS unavailable reasons, and artifact/summary layout.
• Benchmark/profile evidence is recorded in Phase 4 results artifacts or a document that points to the raw artifacts.

Blocked by

None - can start immediately

[jununfly]

This was generated by AI during triage.

Implemented in f04040f on main.

Summary:

• scripts/rust-index-profile.mjs now emits comparable TypeScript/Rust wall-clock and peak RSS evidence.
• RSS sampling now reports rssUnavailableReason when local process RSS cannot be sampled, instead of leaving an unexplained null.
• Profile output includes toolchain metadata (platform, arch) and per-engine RSS fields.
• Phase validation summary exposes profileRssEvidence.
• Baseline evidence for ZCodeGraph, Excalidraw, and Zustand is recorded in docs/benchmarks/2026-06-13-rust-indexing-core-phase-4-profile-baseline.md.

Validation:

npx vitest run __tests__/rust-index-profile.test.ts __tests__/rust-phase3-validation.test.ts
git diff --check

Additional targeted validation before push covered the Phase 4 readiness suites.