docs(control-mapping): MCP emission loop + default-on flags (#227)

docs/features/control-mapping.md

@@ -108,16 +108,25 @@ Every finding maps to its exact control family, with the most specific control o
 - **Generic catch-all controls co-occur.** `mc-20890 secure_development_security_code_review` appears in the top-K for many code-security findings because it is semantically near almost all of them. It's harmless (the judge grounds it, and it never crowds out the specific controls — the SQLi example didn't get it) but is a candidate for future down-weighting.
 - **Corpus classification noise.** The master-controls `verification_method` classification is imperfect — e.g. a documentation control (`eu_declaration_accuracy`) is currently tagged `source_code`. That's a corpus-side data-quality issue, separate from the mapping engine.
 
+## Emitting over MCP — closing the loop
+
+Findings don't just land in the dashboard; they flow to breakpilot-compliance as OSCAL over the scanner's MCP server, so the compliance report is assembled from real, control-tagged findings.
+
+- The MCP server exposes an **`oscal_assessment`** tool: given a `repo_id`, it emits a standard OSCAL 1.1 assessment-results document for that repo's findings — mapped findings target their controls via the stamped `control_refs`, and unmapped findings are reported **as-is** (as observations), so nothing is lost.
+- breakpilot pulls it: `POST /v1/cra/oscal-from-scanner` calls `oscal_assessment` over MCP (Streamable HTTP + bearer) and consumes the pre-computed OSCAL — rather than pulling raw findings and re-assessing.
+
+**Operational note — tenant context over HTTP.** The MCP server is multi-tenant; the bearer token resolves a tenant whose per-tenant database the tools query. rmcp's Streamable HTTP transport runs each session's tool calls in a `tokio::spawn`ed task, and `task_local`s do **not** cross a spawn — so binding the tenant in a per-request middleware `task_local` leaves tool handlers with no context (every call fails `no tenant context`). The fix is to bind the tenant to the **per-session server instance** at creation (the factory runs in the request scope before the spawn), not to a per-request task_local. Until this was fixed, the loop silently failed over HTTP and consumers fell back to demo data.
+
 ## Configuration
 
 | Variable | Effect |
 | --- | --- |
-| `BREAKPILOT_BASE_URL` | breakpilot-compliance root; enables control ingest + Stage 5b. Unset disables all control mapping. |
+| `BREAKPILOT_BASE_URL` | breakpilot-compliance root; enables control ingest + all mapping passes. **Unset disables all control mapping** — findings are produced without `control_refs`. |
-| `BREAKPILOT_SEMANTIC_MAPPING` | Enables Stage 5c (semantic master-controls mapping). Default off. |
+| `BREAKPILOT_SEMANTIC_MAPPING` | Stage 5c (semantic master-controls mapping). **Default on** (validated live). |
-| `BREAKPILOT_GROUNDED_CHECKS` | Enables Stage 5d (grounded surface checks). Default off. |
+| `BREAKPILOT_GROUNDED_CHECKS` | Stage 5d (grounded surface checks). **Default on** (validated live). |
 | `BREAKPILOT_SNAPSHOT_DIR` | Where OSCAL catalog snapshots and the cached control-embedding index live. |
 
-The semantic and grounded passes are gated because they are the heavier, less deterministic paths; they stay off until verified live against a deployed catalog. The live verification lives in `compliance-agent/tests/c5_semantic_live.rs` (ignored; run with `--ignored`).
+The semantic and grounded passes default **on** now that both are validated live; each is still a no-op if `BREAKPILOT_BASE_URL` is unset or the catalog is unreachable, so they only ever add coverage. The live verifications live in `compliance-agent/tests/c5_semantic_live.rs` and `grounded_surface_live.rs` (ignored; run with `--ignored`).
 
 ## Appendix — the master-controls data pipeline