docs(03-02): complete regression guardrails plan

- Add phase summary with task commits, deviations, and verification results
- Record EVAL-02 coverage outcomes and phase readiness notes

Author: PatrickSys

.planning/phases/03-evaluation-guardrails/03-02-SUMMARY.md

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+---
+phase: 03-evaluation-guardrails
+plan: 02
+subsystem: testing
+tags: [tree-sitter, vitest, unicode, parser-reset, indexing]
+requires:
+  - phase: 02-tree-sitter
+    provides: parse-error fallback and symbol-aware chunking baseline
+provides:
+  - Unicode slicing regression coverage for symbol extraction
+  - Large file and generated file skip regression coverage
+  - Parser timeout/reset and cleanup regression coverage
+affects: [phase-05-ast-aligned-chunking, phase-09-search-quality]
+tech-stack:
+  added: []
+  patterns: [utf8-safe extraction guardrails, parser cache eviction on failure]
+key-files:
+  created:
+    - tests/tree-sitter-unicode-slicing.test.ts
+    - tests/tree-sitter-cleanup.test.ts
+    - tests/indexer-large-file-skip.test.ts
+  modified:
+    - src/utils/tree-sitter.ts
+key-decisions:
+  - "Set Tree-sitter timeout via setTimeoutMicros when available, but fail open if timeout API signature differs across runtimes."
+  - "Include export_statement parent range for symbol content so exported declarations remain complete in extracted chunks."
+patterns-established:
+  - "Guardrail tests use local grammars/mocks only and remain network-free."
+  - "Parser failures evict cache entries to avoid poisoning subsequent parses."
+requirements-completed: [EVAL-02]
+duration: 4 min
+completed: 2026-02-20
+---
+
+# Phase 03 Plan 02: Regression Guardrails Summary
+
+**Tree-sitter extraction now has Unicode-safe guards with parser reset/cleanup hardening, backed by focused regressions for Unicode boundaries, parse failure recovery, and large-file skipping.**
+
+## Performance
+
+- **Duration:** 4 min
+- **Started:** 2026-02-20T18:31:16Z
+- **Completed:** 2026-02-20T18:36:04Z
+- **Tasks:** 2
+- **Files modified:** 4
+
+## Accomplishments
+- Hardened `extractTreeSitterSymbols` with UTF-8 extraction path, 1 MiB parse budget guard, timeout wiring, and parser cache eviction/reset on failures.
+- Added regression tests that lock Unicode slicing behavior, parser cleanup/reset behavior, and large/generated file skip behavior.
+- Verified all new regressions pass with network-free Vitest execution.
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Harden Tree-sitter extraction for Unicode + reset behavior** - `375a48f` (fix)
+2. **Task 2: Add regression tests for Unicode slicing, large file skipping, and cleanup/reset** - `a1c71de` (fix)
+
+**Plan metadata:** `58adead`
+
+## Files Created/Modified
+- `src/utils/tree-sitter.ts` - Adds parse guards, timeout wiring, parser cache eviction/reset, and export-range-aware symbol extraction.
+- `tests/tree-sitter-unicode-slicing.test.ts` - Reproduces and protects against Unicode boundary symbol slicing corruption.
+- `tests/tree-sitter-cleanup.test.ts` - Mocks parser behavior to verify `tree.delete()` cleanup and parser reset/eviction paths.
+- `tests/indexer-large-file-skip.test.ts` - Validates oversize regular and generated files are skipped without breaking indexing.
+
+## Decisions Made
+- Used a best-effort timeout hook: call `setTimeoutMicros` when present, but do not fail extraction if timeout API wiring differs across parser builds.
+- Expanded symbol content range to include `export_statement` parent nodes, preserving complete exported declaration headers.
+
+## Deviations from Plan
+
+### Auto-fixed Issues
+
+**1. [Rule 1 - Bug] Fixed exported declaration truncation under Unicode boundary conditions**
+- **Found during:** Task 2 (Unicode regression execution)
+- **Issue:** Byte-slice extraction produced incomplete exported declaration headers in a Unicode-preceded file.
+- **Fix:** Added compatibility extraction fallback and export parent-range capture in `buildSymbol`.
+- **Files modified:** src/utils/tree-sitter.ts
+- **Verification:** `pnpm vitest run tests/tree-sitter-unicode-slicing.test.ts`
+- **Committed in:** a1c71de
+
+---
+
+**Total deviations:** 1 auto-fixed (1 bug)
+**Impact on plan:** Deviation was required to satisfy the guardrail objective and keep extraction behavior correct across runtime offset semantics.
+
+## Issues Encountered
+None.
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+Regression coverage for EVAL-02 failure surfaces is in place and passing.
+Ready for 03-03 shared eval harness and multi-codebase `npm run eval` wiring.
+
+---
+*Phase: 03-evaluation-guardrails*
+*Completed: 2026-02-20*
+
+## Self-Check: PASSED