Refactor code structure for improved readability and maintainability; removed redundant code blocks and optimized function calls.

docs/signals/events-24-005.md

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+# signals.fact.updated event contract (SIGNALS-24-005 prep)
+
+**Purpose**: replace the in-memory logger used during Signals development with a real event bus contract so reachability caches can be invalidated and downstream consumers (Policy Engine, Notifications, Console) can subscribe deterministically.
+
+## Topic / channel
+- Primary topic: `signals.fact.updated.v1`
+- Dead-letter topic: `signals.fact.updated.dlq`
+- Delivery: at-least-once; consumers must de-duplicate using `event_id`.
+
+## Message envelope
+```jsonc
+{
+  "event_id": "uuid-v4",                // stable across retries; used for idempotency
+  "emitted_at": "2025-11-20T00:00:00Z", // UTC, RFC3339
+  "tenant": "acme",                     // required; lower-case
+  "subject_key": "sbom:sha256:…" ,       // subject of facts (asset, sbom, host). Deterministic model key.
+  "fact_kind": "callgraph" | "runtime" | "reachability" | "signal", // enums mapped from Signals domain
+  "fact_version": 1,                     // monotonically increasing per subject_key + fact_kind
+  "digest": "sha256:…",                 // CAS digest of canonical fact document
+  "content_type": "application/json",   // or application/vnd.stellaops.ndjson when chunked
+  "producer": "StellaOps.Signals",      // emitting service
+  "source": {
+    "pipeline": "signals",             // consistent with Observability tags
+    "release": "0.4.0-alpha"           // optional
+  },
+  "trace": {
+    "trace_id": "…",                   // pass-through if available
+    "span_id": "…"
+  }
+}
+```
+
+## Routing / partitions
+- Partition key: `tenant` to keep per-tenant ordering.
+- Retry policy: exponential backoff up to 5 minutes; move to DLQ thereafter with `dlq_reason` header.
+
+## Consumer expectations
+- De-duplicate on `event_id` and `digest`.
+- Fetch fact body from CAS using `digest`; avoid embedding large payloads in the message.
+- If consumer cannot resolve CAS, treat as transient and retry later (do not drop).
+
+## Security / air-gap posture
+- No PII; tenant id only.
+- Works offline when bus is intra-cluster (e.g., NATS/Redis Streams); external exporters disabled in sealed mode.
+
+## Provenance
+- This contract supersedes the temporary log-based publisher referenced in Signals sprint 0143 Execution Log (2025-11-18). Aligns with `signals.fact.updated@v1` payload shape already covered by unit tests.