# Performance Review Report

**Branch**: feat/134-system-prompt-support -> main
**Date**: 2026-04-18

## Issues in Your Changes (BLOCKING)

_No blocking performance issues found._

## Issues in Code You Touched (Should Fix)

_No should-fix performance issues found._

## Pre-existing Issues (Not Blocking)

### MEDIUM

**Synchronous filesystem I/O in GeminiBasePromptCache blocks the event loop** - `src/implementations/gemini-adapter.ts:59-60, 85-99`
**Confidence**: 65%
- Problem: `writeFileSync`, `readFileSync`, `statSync`, `existsSync` are used in `buildCombinedFile()` and `#ensureCacheLoaded()`. These synchronous operations block the Node.js event loop during execution. However, these calls are per-task (one invocation per worker spawn/cleanup), not in a loop or hot path, and the GeminiAdapter is instantiated once at startup.
- Mitigating factors: (1) The constructor's `mkdirSync` runs once at startup, (2) `buildCombinedFile` is called once per task spawn, (3) cache avoids repeated disk reads after first load, (4) files are small (max 64KB guard). The blocking duration is negligible for typical usage.
- This is pre-existing architecture (sync I/O for the cache was an intentional design choice noted in the PR review as a deferred extraction). Not a regression from this PR.

## Suggestions (Lower Confidence)

- **operationalContract string is always constructed even when unused** - `src/services/orchestrator-prompt.ts:141-159` (Confidence: 60%) -- `buildOrchestratorPrompt` always builds the `operationalContract` template string even when the caller will not use it (no custom systemPrompt). The cost is negligible (single template literal evaluation with a few interpolations), but if the function were called frequently, a lazy construction pattern could avoid the allocation.

## Summary

| Category | CRITICAL | HIGH | MEDIUM | LOW |
|----------|----------|------|--------|-----|
| Blocking | 0 | 0 | 0 | 0 |
| Should Fix | 0 | 0 | 0 | 0 |
| Pre-existing | 0 | 0 | 1 | 0 |

**Performance Score**: 9/10
**Recommendation**: APPROVED

### Rationale

The changes in this PR are clean from a performance perspective:

1. **No N+1 patterns** -- No database queries inside loops. The `systemPrompt` field is threaded through existing data paths (Zod schemas, domain objects, DB serialization) without introducing new queries.

2. **No blocking I/O regressions** -- The `mkdirSync` was hoisted from `buildCombinedFile()` (called per-task) to the constructor (called once at startup). This is a performance improvement, not a regression. The remaining sync I/O in `buildCombinedFile` and `#ensureCacheLoaded` is per-task and guarded by an in-memory cache.

3. **No unbounded caches** -- The `GeminiBasePromptCache` caches a single string (`#cached`) with explicit invalidation via `invalidate()` and staleness checking (30-day TTL). No risk of unbounded growth.

4. **No sequential-when-parallel-possible** -- The `operationalContract` construction is a pure string template, not an async operation. No missed `Promise.all` opportunities.

5. **Path-traversal guard is O(1)** -- The `path.resolve` + `startsWith` check in `cleanupTaskFile` is a constant-time string operation with no performance concern.

6. **Schedule repository Zod schema additions** -- Adding `systemPrompt: z.string().optional()` to `TaskRequestSchema` and `LoopConfigSchema` has negligible impact on parse performance (one additional optional field check per deserialization).
