M25: expose provenance-aware knowledge statistics

backend/app/services/knowledge/__init__.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from datetime import datetime
 from functools import lru_cache
 from typing import Literal, Protocol
 
@@ -8,6 +9,7 @@ from pydantic import BaseModel
 from app.core.config import get_settings
 
 EvidenceState = Literal["grounded", "insufficient", "unavailable"]
+KnowledgeStatisticsState = Literal["verified", "sync_reported", "not_reported"]
 
 
 class SourceCard(BaseModel):
@@ -36,6 +38,11 @@ class KnowledgeHealth(BaseModel):
     # A provider may be healthy without exposing a corpus-size endpoint. `None` means
     # unknown, never "zero procedures".
     document_count: int | None
+    source_document_count: int
+    reported_synced_document_count: int | None
+    reported_failed_document_count: int | None
+    last_sync_at: datetime | None
+    statistics_state: KnowledgeStatisticsState
 
 
 class KnowledgeProvider(Protocol):