Document validation architecture and renderer faithfulness findings

- document Entity Registry and Meeting Context V2 architecture
- preserve meeting_context.yaml as the authoritative meeting-specific input
- define immutable authoritative metadata across all pipeline stages
- restrict Constraint Repair to deterministic structured-data operations
- record BUG-003 root cause and deferred entity-verification resolution
- document BUG-005 attendance-consistency design
- add BUG-006 renderer faithfulness root-cause analysis
- distinguish Engineering Readiness from Practical Usability
- update the persistent regression bug tracker

docs/pipeline.md

@@ -30,6 +30,8 @@ Canonical Meeting Knowledge and every Output View renderer.
 
 # Pipeline Overview
 
+Current analysis pipeline:
+
 ```text
 Whisper Transcript
         │
@@ -73,6 +75,46 @@ extraction, deterministic prompt injection and minimal extraction JSON
 provenance. Later Canonicalizer, Semantic Consolidator, Canonical Meeting
 Knowledge and renderer integration remains future work.
 
+Accepted future Meeting Context V2 preparation flow:
+
+```text
+Whisper
+        │
+        ▼
+Entity Detection
+        │
+        ▼
+User Confirmation
+        │
+        ▼
+Entity Registry Update
+        │
+        ▼
+Meeting Context Builder
+        │
+        ▼
+meeting_context.yaml
+        │
+        ▼
+Extraction Pipeline
+```
+
+This preparation flow is not implemented. It is the accepted long-term
+direction for reducing manual Meeting Context work while preserving explicit
+user control. The Entity Registry is the persistent cross-meeting knowledge
+source for confirmed entities, aliases and organizational metadata. It stores
+stable internal IDs and confirmed aliases, and never updates itself
+automatically.
+
+For each meeting run, `meeting_context.yaml` remains the authoritative
+meeting-specific Point of Truth and reproducible input artifact consumed by the
+pipeline. V2 changes how that artifact is prepared: it may be generated or
+assisted from Registry data, user confirmations and meeting metadata. The
+Registry must not override explicit meeting-specific confirmations, and
+Registry changes after a meeting run must not silently change the historical
+Meeting Context used for that run. Similarity suggestions and unknown entity
+classifications require explicit user confirmation.
+
 ---
 
 # Stage 1 – Normalization