feat: Stage 5 synthesizer + pipeline orchestrator + feature flag wiring (issue #29)
- Add app/services/diagnose/synthesizer.py: SummarySynthesizer (Stage 5)
- Builds structured LLM prompt from ranked hypotheses, timeline, RAG context
- Excludes suppressed hypotheses from the narrative prompt
- Deterministic fallback when no LLM configured or LLM call fails
- Same cf-orch task endpoint + direct OpenAI-compat fallback pattern as other stages
- Replace pipeline.py stub with full run_pipeline() async generator
- Orchestrates all 5 stages via asyncio.to_thread for each synchronous stage
- Yields typed SSE event dicts: status, pipeline_stage (1-4), hypotheses, reasoning, done
- Suppressor counts (active vs suppressed) reported in stage 4 event message
- Wire MULTI_AGENT_ENABLED feature flag into diagnose_stream()
- TURNSTONE_MULTI_AGENT_DIAGNOSE=true routes through run_pipeline()
- pipeline emits its own done event; legacy path unchanged when flag is false
- Import of run_pipeline added to __init__.py
- Add 21 new tests (350 -> 371 passing):
- tests/test_diagnose_synthesizer.py: 8 tests (with/without LLM, suppressed,
empty ranked, LLM failure fallback)
- tests/test_diagnose_pipeline.py: 13 tests (flag off, flag on event sequence,
empty entries, no LLM, stage 1 cluster count message)
Closes: #29
pyr0ball
14bec5769b