prep docs and service updates

docs/modules/policy/prep/2025-11-20-simulation-bridge-prep.md

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+# Simulation Bridge Prep — PREP-POLICY-ENGINE-30-002-SIMULATION-BRIDGE-C
+
+Status: Draft (2025-11-20)
+Owners: Policy Guild · Cartographer Guild
+Scope: Capture the required simulation bridge inputs and outputs so POLICY-ENGINE-30-002 can start once overlay schema (30-001) lands.
+
+## Dependencies
+- Overlay projection contract (30-001) — needs metrics/log schema from 29-004.
+- Cartographer graph API shape for reachability overlays.
+
+## Proposed contract (to validate once 30-001 freezes)
+- Input: overlay projection payload from 30-001 plus reachability summaries from Cartographer.
+- Output (draft schema):
+  - `simulation_id` (ULID), `tenant_id`, `scenario` descriptor.
+  - `inputs`: overlay snapshot hash, policy profile hash, reachability baseline hash.
+  - `results[]`: `{component_purl, advisory_id, status_before, status_after, reason, trace_ref}`.
+  - `metrics`: duration, rule_eval_count, graph_nodes_touched.
+- Determinism: stable ordering by `(tenant_id, component_purl, advisory_id)`; timestamps UTC RFC3339.
+
+## Acceptance to flip PREP to DONE
+- Overlay schema (30-001) version/Hash referenced in this file.
+- Draft JSON schema for simulation bridge saved under `docs/modules/policy/schemas/simulation-bridge@draft.json`.
+- Sample payload placed under `docs/modules/policy/samples/simulation-bridge@draft.json`.
+
+## Handoff
+Use this as the prep artefact for PREP-POLICY-ENGINE-30-002-SIMULATION-BRIDGE-C. Update hashes and samples once 30-001 publishes the overlay schema; then move the implementation task to DOING.