observerd: /observer/inbox + multi-coord stress phase 1c (priority-ordered events)

Phase 3 ask: real-world inbox-style event injection during the stress
test. Coordinators in production receive emails + SMS that trigger
contract responses; the substrate has to RECORD these signals AND
react with a search using the embedded demand. This commit lands the
endpoint and exercises it end-to-end in the stress harness.

observerd surface:
- New POST /observer/inbox route — accepts {type, sender, subject,
  body, priority, tag} and records as ObservedOp with
  Source=SourceInbox. Type must be email|sms; body required;
  priority defaults to medium. The handler ONLY records — downstream
  triggers (search, ingest, etc.) are the caller's concern, recorded
  separately. Keeps the witness role pure.
- New observer.SourceInbox = "inbox" alongside SourceMCP /
  SourceScenario / SourceWorkflow.
- Three contract tests on the new route (happy path / bad type / empty
  body), router-mount test extended, all green.

Stress harness phase 1c (Hour 9):
- 6 inbox events fire in priority order (urgent → high → medium):
    2 urgent emails (forklift Cleveland, production Indianapolis)
    1 high email (crane Chicago)
    1 high sms (bilingual safety Indianapolis)
    1 medium sms (drone Chicago)
    1 medium email (warehouse Milwaukee FYI)
- Each event:
    1. POSTs to /v1/observer/inbox (recorded by observerd)
    2. Triggers matrix.search using a parsed demand (the demand
       extraction is hard-coded for now; production needs a small
       LLM to parse from body)
    3. Captures both as events in the run JSON

Run #006 result (with v2-moe embedder + all phases including inbox):

  Diversity:
    Same-role-across-contracts Jaccard = 0.000 (n=9)
    Different-roles-same-contract Jaccard = 0.046 (n=18)
  Determinism: 1.000
  Verbatim handover: 4/4 (100%)
  Paraphrase handover: 4/4 (100%)
  Inbox burst:
    6/6 events accepted by observerd (200 status, all recorded)
    6/6 triggered searches produced distinct top-1 worker IDs
    distance distribution: 0.24 (Indy production) → 0.71 (Chicago
    drone surveyor — honest stretch since drones aren't in the
    5K-worker corpus, system surfaces closest neighbor at high
    distance rather than fabricating)

The drone-Chicago case is the architectural-honesty signal: when
the demand asks for a specialist NOT in the roster, the system
returns the closest semantic neighbor with a distance that flags
"this is a stretch." Coordinators reading distances see "we don't
have a great match here" rather than a confident wrong answer.

Total events captured: 67 (was 61 pre-inbox).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

reports/reality-tests/multi_coord_stress_006.md

@@ -0,0 +1,82 @@
+# Multi-Coordinator Stress Test — Run 006
+
+**Generated:** 2026-04-30T13:33:24.568124731Z
+**Coordinators:** alice / bob / carol (each with own playbook namespace: `playbook_alice` / `playbook_bob` / `playbook_carol`)
+**Contracts:** alpha_milwaukee_distribution / beta_indianapolis_manufacturing / gamma_chicago_construction
+**Corpora:** `workers,ethereal_workers`
+**K per query:** 8
+**Total events captured:** 67
+**Evidence:** `reports/reality-tests/multi_coord_stress_006.json`
+
+---
+
+## Diversity — is the system locking into scenarios or cycling?
+
+| Metric | Mean Jaccard | n pairs | Interpretation |
+|---|---:|---:|---|
+| Same role across different contracts | 0 | 9 | Lower = more diverse (different region/cert mix → different workers) |
+| Different roles within same contract | 0.04603174603174603 | 18 | Should be near-zero (different roles = different worker pools) |
+
+**Healthy ranges:**
+- Same role across contracts: < 0.30 means the system is genuinely picking different workers per region/contract.
+- Different roles same contract: < 0.10 means role-specific retrieval is working.
+- If either is > 0.50, the system is "cycling" the same handful of workers regardless of query intent.
+
+---
+
+## Determinism — same query reissued, top-K stability
+
+| Metric | Value |
+|---|---:|
+| Mean Jaccard on retrieval-only reissue | 1 |
+| Number of reissue pairs | 12 |
+
+**Interpretation:**
+- ≥ 0.95: HNSW retrieval is highly deterministic; reissues land on near-identical top-K. Good — system locks into a stable view of "best workers for this query."
+- 0.80 – 0.95: Some HNSW or embed variance, acceptable.
+- < 0.80: Retrieval is unstable — reissues see substantially different results, suggesting either embed nondeterminism (Ollama returning slightly different vectors) or vectord nondeterminism (HNSW insertion order affecting recall).
+
+---
+
+## Learning — handover hit rate
+
+Bob takes Alice's contract using Alice's playbook namespace. Did Alice's recorded answers surface in Bob's results?
+
+| Metric | Value |
+|---|---:|
+| Verbatim handover queries run | 4 |
+| Alice's recorded answer at Bob's top-1 (verbatim) | 4 |
+| Alice's recorded answer in Bob's top-K (verbatim) | 4 |
+| **Verbatim handover hit rate (top-1)** | **1** |
+| Paraphrase handover queries run | 4 |
+| Alice's recorded answer at Bob's top-1 (paraphrase) | 4 |
+| Alice's recorded answer in Bob's top-K (paraphrase) | 4 |
+| **Paraphrase handover hit rate (top-1)** | **1** |
+
+**Interpretation:**
+- Verbatim hit rate ≈ 1.0: trivial case — Bob runs identical queries; should always hit.
+- Paraphrase hit rate ≥ 0.5: institutional memory survives wording change — the harder learning property.
+- Paraphrase hit rate ≈ 0.0: Bob's paraphrases drift past the inject threshold, so Alice's recordings don't activate. Same caveat as the playbook_lift paraphrase pass.
+
+---
+
+## Per-event capture
+
+All matrix.search responses live in the JSON — top-K with worker IDs, distances, and per-corpus counts. Search by phase:
+
+```bash
+jq '.events[] | select(.phase == "merge")' reports/reality-tests/multi_coord_stress_006.json
+jq '.events[] | select(.coordinator == "alice" and .phase == "baseline")' reports/reality-tests/multi_coord_stress_006.json
+jq '.events[] | select(.role == "warehouse worker") | {phase, contract, top_k_ids: [.top_k[].id]}' reports/reality-tests/multi_coord_stress_006.json
+```
+
+---
+
+## What's NOT in this run (Phase 1 deliberately defers)
+
+- **48-hour clock.** Events fire as discrete steps, not on a timeline.
+- **Email / SMS ingest.** No endpoints exist on the Go side yet.
+- **New-resume injection mid-run.** The corpus is fixed at the start.
+- **Langfuse traces.** Need Go-side wiring.
+
+These are Phase 2/3. The Phase 1 substrate is what the time-based runner will mount on top of.