diff --git a/.artifacts/ReviewIQ-Architecture-v3.1.md b/.artifacts/ReviewIQ-Architecture-v3.1.md
index 1cb9e6c..14e6231 100644
--- a/.artifacts/ReviewIQ-Architecture-v3.1.md
+++ b/.artifacts/ReviewIQ-Architecture-v3.1.md
@@ -233,7 +233,7 @@ CREATE TABLE reviews_enriched (
 
     -- Quality control
     trust_score         FLOAT DEFAULT 1.0,      -- 0.0 to 1.0
-    dedup_group_id      TEXT,                   -- Groups duplicate/near-duplicate reviews
+    dedup_group_id      TEXT,                   -- Tenant-scoped: format "{business_id}:{hash}"
     is_suspicious       BOOLEAN DEFAULT FALSE,
 
     -- Processing metadata
@@ -405,7 +405,11 @@ CREATE INDEX idx_events_review ON issue_events(source, review_id, review_version
 
 ### 2.4 Unified Analytics Spine
 
-**Design Decision**: `place_id = 'ALL'` is the sentinel for "all locations" rollups. This avoids NULL handling complexity while keeping the schema simple.
+**Design Decision**: Sentinel value conventions (do not normalize):
+- `place_id = 'ALL'` — spatial rollup (all locations)
+- `subject_id = 'all'` — semantic rollup (all subjects within type)
+
+Case matters: `'ALL'` ≠ `'all'`. This avoids NULL handling while keeping the schema simple.
 
 ```sql
 -- Fact table: pre-aggregated time-series metrics