prep docs and service updates

docs/modules/excititor/prep/2025-11-20-consensus-removal-prep.md

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+# Excititor · Consensus Removal Prep (AOC-19-004)
+
+- **Date:** 2025-11-20
+- **Working directory:** `src/Excititor/__Libraries/StellaOps.Excititor.Core` + `src/Excititor/StellaOps.Excititor.WebService`
+- **Scope:** PREP-EXCITITOR-CORE-AOC-19-004-REMOVE-CONSENS
+
+## Objective
+Define the cutover plan to remove legacy consensus/severity merge logic so Excititor remains aggregation-only and emits raw facts for downstream Policy/Concelier consumers.
+
+## Required changes (contract)
+- **API/Storage:**
+  - Deprecate/disable any fields representing merged severity/status (`mergedSeverity`, `consensusScore`, `computedStatus`).
+  - Retain raw source fields: `status`, `justification`, `impact`, `affects`, `references`, `notes`, `provenance`, `reconciledFrom`.
+  - Add boolean `consensusDisabled: true` to existing documents during migration for audit.
+- **Ingestion pipeline:**
+  - When dual/conflicting statuses arrive, store both observations; no reconciliation beyond stable ordering.
+  - Maintain deterministic ordering when multiple observations share `(tenant, advisoryId, component)` — sort by `ingestedAt`, then `source`, then `evidenceHash`.
+- **Feature flag:** `excititor:aoc:disableConsensus` default `true`; only temporary `false` allowed for rollback during migration.
+- **Telemetry:** counter `excititor.ingest.consensus.disabled` tagged by `tenant`, `source`, `connectorId`; increment once per batch after flag applied.
+
+## Migration outline
+- Backfill step sets `consensusDisabled=true` where merged fields exist, and clears merged fields without touching raw observations.
+- Tests must assert merged fields are absent/null after migration and ingestion flows do not write them.
+
+## Acceptance for prep completion
+- Cutover rules, telemetry, and migration outline frozen here; implementation tasks must follow or update this note and sprint risks.
+