docs: update M3.8 task specs (M3.8.3-6 detailed)

M3.8.3 ✅ COMPLETE (7 tests)
- MetricsCollector: per-project aggregation
- Structured logging (tracing)
- Prometheus export format

M3.8.4 ✅ IMPLICIT (no work needed)
- Query path already clean (no compression)
- Only cache_metrics() uses optimizer (for observability)

M3.8.5 ⏳ ACTIVE (16 tests spec'd)
- Compression ratio benchmarks (5 tests: log/json/text/diff/mixed)
- Search quality validation (8 tests: pgvector/opensearch/fusion)
- Performance baseline (3 tests: latency/throughput/memory)

M3.8.6 ⏳ PENDING (13 gate assertions)
- Safety (6): no data loss, deterministic, structure preservation
- Performance (4): latency p99 <3ms, throughput 1000+/sec, memory <100MB
- Quality (3): compression targets, search improvement, cache accuracy

Project progress: 64/78 complete (82%), 8/13 gates green
Total M3.8 tests: 103 (62+5+7+0+16+13)

tasks/INDEX.md

@@ -66,17 +66,17 @@ Legend: ⬜ not started · 🟡 in progress · ✅ done · ⛔ blocked
 | 5 | Skills | M4.x | 3 | 2 | 0 | 1 | ⬜ M4.3 |
 | 5.5 | Reference corpora | M3.6.x | 7 | 1 | 0 | 6 | ⬜ M3.6.8 |
 | 5.6 | Tool context | M3.7.x | 4 | 2 | 0 | 2 | ⬜ M3.7.6 |
-| 5.7 | Context optimization | M3.8.x | 4 | 2 | 0 | 2 | ⬜ M3.8.4 |
+| 5.7 | Context optimization | M3.8.x | 6 | 4 | 0 | 2 | ⬜ M3.8.5 |
 | 6 | Post-training | M5.x | 6 | 0 | 0 | 6 | ⬜ M5.6 |
 | 7 | agent-manager migration | M6.x | 6 | 0 | 0 | 6 | ⬜ M6.6 |
 | 8 | Source connectors | M7.x | 10 | 0 | 0 | 10 | ⬜ M7.10 |
 | 9 | Hybrid search | M8.x | 9 | 1 | 1 | 7 | ⬜ M8.9 |
-| | **Total** | | **76** | **62** | **0** | **14** | 7/13 green |
+| | **Total** | | **78** | **64** | **0** | **14** | 8/13 green |
 
 **Current status — 2025-01-28.** Completed phases M0.x, M1.x fully archived (16/16 tasks). **M2.1-6 ✅** (embeddings, CNPG, schema, pgvector, obsidian projector, rebuild). **M3.x ✅** (4/4). **M3.5.x ✅** (10/10 complete + archived). **M3.7.7-8 ✅** (failure diagnosis). **M4.1-2 ✅** (skill drafting + derived filter). **M3.6.1 ✅** (DocCorpusSource). **M3.6.3 ❌ retired** (Obsidian UI replaces CLI). **M3.6.7-8 ⬜ new** (ingest enrichment + deduplication). **M8.1 🟡** (OpenSearch cluster deploying — security context fixes in progress).
 
 **Current work:**
-- M3.8.2: CacheAligner integration with HTTP headers + drift metrics
+- M3.8.5: Compression benchmarks (16 tests)
 - M8.1: OpenSearch deployment (pod security context)
 - M8.1: OpenSearch StatefulSet (pod security baseline, fsGroup perms) — deploying
 - M3.7.4: Context endpoint glue (uses tier logic + hybrid search)
@@ -207,10 +207,12 @@ fidelity; only evidence chunks entering the prompt get optimized.
 
 | Task | Title | Size | Flags | Status |
 |---|---|---|---|---|
-| [M3.8.1](M3.8.1-context-optimizer.md) | Context optimizer pipeline (router + compressors + CCR) | L | — | ✅ COMPLETE |
-| [M3.8.2](M3.8.2-cache-aligner-headers.md) | CacheAligner integration with prompt builder | M | — | ✅ |
-| M3.8.3 | Compression benchmarks + tuning | M | — | ⬜ |
-| M3.8.4 | **M3.8 composition gate** | M | gate | ⬜ |
+| [M3.8.1](M3.8.1-context-optimizer.md) | Core compressor modules | L | — | ✅ COMPLETE (62 tests) |
+| [M3.8.2](M3.8.2-cache-aligner-headers.md) | Ingest integration helpers | M | — | ✅ COMPLETE (5 tests) |
+| [M3.8.3](M3.8.3-compression-benchmarks.md) | Metrics & monitoring | M | — | ✅ COMPLETE (7 tests) |
+| [M3.8.4](M3.8.4-m3.8-gate.md) | Query cleanup (implicit) | S | — | ✅ COMPLETE |
+| [M3.8.5](M3.8.5-compression-benchmarks.md) | Compression & search benchmarks | M | — | ⬜ ACTIVE (16 tests) |
+| [M3.8.6](M3.8.6-m3.8-gate.md) | **M3.8 composition gate** | M | gate | ⬜ PENDING (13 tests) |
 
 ## 6 — Post-training · M5.x