diff --git a/migrations/V5__truth_scoring.sql b/migrations/V5__truth_scoring.sql
new file mode 100644
index 0000000..499d214
--- /dev/null
+++ b/migrations/V5__truth_scoring.sql
@@ -0,0 +1,34 @@
+-- V5: Add truth scoring columns for the Truth Engine integration
+-- Part of: https://gitea.ingwaz.work/Ingwaz/openbrain-mcp/issues/31
+--
+-- All columns are nullable — existing memories start unscored and
+-- get populated by the background truth scoring worker.
+--
+-- Rollback (manual):
+--   ALTER TABLE memories
+--     DROP COLUMN IF EXISTS truth_value,
+--     DROP COLUMN IF EXISTS truth_confidence,
+--     DROP COLUMN IF EXISTS truth_category,
+--     DROP COLUMN IF EXISTS truth_evaluated_at,
+--     DROP COLUMN IF EXISTS ecan_sti,
+--     DROP COLUMN IF EXISTS ecan_lti;
+--   DROP INDEX IF EXISTS idx_memories_truth_category;
+--   DROP INDEX IF EXISTS idx_memories_truth_unevaluated;
+
+ALTER TABLE memories
+  ADD COLUMN truth_value        REAL,
+  ADD COLUMN truth_confidence    REAL,
+  ADD COLUMN truth_category      TEXT,
+  ADD COLUMN truth_evaluated_at  TIMESTAMPTZ,
+  ADD COLUMN ecan_sti            REAL,
+  ADD COLUMN ecan_lti            REAL;
+
+-- Partial index: quickly find memories by truth category
+CREATE INDEX idx_memories_truth_category
+  ON memories (truth_category)
+  WHERE truth_category IS NOT NULL;
+
+-- Partial index: efficiently find unscored memories for the background worker
+CREATE INDEX idx_memories_truth_unevaluated
+  ON memories (created_at)
+  WHERE truth_evaluated_at IS NULL;
diff --git a/src/db.rs b/src/db.rs
index 5cd70c6..ae3447b 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -30,6 +30,13 @@ pub struct MemoryRecord {
     pub metadata: serde_json::Value,
     pub created_at: chrono::DateTime<chrono::Utc>,
     pub expires_at: Option<chrono::DateTime<chrono::Utc>>,
+    // Truth scoring fields (populated by background worker)
+    pub truth_value: Option<f32>,
+    pub truth_confidence: Option<f32>,
+    pub truth_category: Option<String>,
+    pub truth_evaluated_at: Option<chrono::DateTime<chrono::Utc>>,
+    pub ecan_sti: Option<f32>,
+    pub ecan_lti: Option<f32>,
 }
 
 /// Query result with similarity score
@@ -299,6 +306,13 @@ impl Database {
                     metadata: row.get("metadata"),
                     created_at: row.get("created_at"),
                     expires_at: row.get("expires_at"),
+                    // Truth fields will be populated by issue #39
+                    truth_value: None,
+                    truth_confidence: None,
+                    truth_category: None,
+                    truth_evaluated_at: None,
+                    ecan_sti: None,
+                    ecan_lti: None,
                 },
                 similarity: row.get("hybrid_score"),
                 vector_score: row.get("vector_score"),