poimen-memory/tasks/M3.8.4-m3.8-gate.md

# M3.8.4 — Query Path Cleanup (IMPLICIT - COMPLETE)

| Field | Value |
|---|---|
| Phase | M3.8 — Context optimization |
| Size | S — 0 days (no changes needed) |
| Status | ✅ COMPLETE |
| Depends | M3.8.3 |
| Blocks | M3.8.5 |

## Summary

✅ **IMPLICIT COMPLETION**

When M3.8 architecture was corrected (ingest vs query), the query path was already clean:

**Current State:**
- ❌ NO query-path compression in `build_cache_aligned()`
- ✅ Only `cache_metrics()` calls optimizer (for metrics collection only, not compression)
- ✅ Actual chunks sent to LLM are unmodified
- ✅ Optimization happens at ingest time via M3.8.2 helpers

**What Didn't Need Changing:**
- `PromptBuilder::build_cache_aligned()` — Already doesn't compress chunks
- `PromptBuilder::cache_metrics()` — Only uses optimizer for token estimation (okay for metrics)
- `PromptBuilder::build()` — Legacy path, unmodified

**Why This is Better:**
- Clean separation: ingest optimizes, query doesn't
- LLM gets pre-optimized chunks from search results
- No per-query optimization overhead
- Cache metrics track drift for observability (non-destructive)

## Verification

All prompt tests still passing (11 tests):
```
test prompt::tests::test_cache_aligned_chunk_budget_exceeded ... ok
test prompt::tests::test_cache_aligned_contains_query ... ok
test prompt::tests::test_cache_aligned_memory_budget_exceeded ... ok
test prompt::tests::test_cache_aligned_produces_two_user_messages ... ok
test prompt::tests::test_cache_prefix_is_stable_across_chunks ... ok
test prompt::tests::test_cache_prefix_is_stable_across_memory_changes ... ok
test prompt::tests::test_cache_prefix_tokens_positive ... ok
test prompt::tests::test_headroom_positive_under_budget ... ok
test prompt::tests::test_legacy_build_still_works ... ok
test prompt::tests::test_render_chunk_multiple_roles ... ok
test prompt::tests::test_render_chunk_single_record ... ok
```

## Files Verified

- `crates/mem-core/src/prompt.rs` — No query-path compression
- `crates/mem-core/src/optimizer/mod.rs` — Optimizer available for metrics only
- No changes required

## Status

✅ **Complete**

This task represents "no work needed" because the architecture was corrected upfront:
- Optimizer at ingest (M3.8.2) ✅
- Metrics collection in query (M3.8.3) ✅
- No compression in query ✅

The query path is already clean.