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docs/09_API_CLI_REFERENCE.md

@@ -646,6 +646,25 @@ Persisted documents capture the canonical envelope (`payload` field), tenant/nod
 
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+### 2.10 Signals - Reachability evidence chain
+
+Signals APIs (base path: `/signals`) provide deterministic ingestion + scoring for the reachability evidence chain (callgraph -> runtime facts -> unknowns -> reachability facts) consumed by Policy and UI explainers.
+
+| Method | Path | Scope | Notes |
+|--------|------|-------|-------|
+| `POST` | `/signals/callgraphs` | `signals:write` | Ingest a callgraph artifact (base64 JSON); response includes `graphHash` (sha256) and CAS URIs. |
+| `POST` | `/signals/runtime-facts` | `signals:write` | Ingest runtime hit events (JSON). |
+| `POST` | `/signals/runtime-facts/ndjson` | `signals:write` | Stream NDJSON events (optional gzip) with subject in query params. |
+| `POST` | `/signals/unknowns` | `signals:write` | Ingest unresolved symbols/edges; influences `unknownsPressure`. |
+| `GET` | `/signals/facts/{subjectKey}` | `signals:read` | Fetch `ReachabilityFactDocument` including `metadata.fact.digest` and per-target `states[]`. |
+| `POST` | `/signals/reachability/recompute` | `signals:admin` | Recompute reachability for explicit targets and blocked edges. |
+
+Docs & samples:
+- `docs/api/signals/reachability-contract.md`
+- `docs/api/signals/samples/callgraph-sample.json`
+- `docs/api/signals/samples/facts-sample.json`
+- `docs/reachability/lattice.md`
+
 ### 2.9 CVSS Receipts (Policy Gateway)
 
 Policy Gateway proxies the Policy Engine CVSS v4 receipt APIs. Scopes: `policy.run` for create/amend, `findings.read` for read/history/policies.