diff --git a/migrations/018_fix_assignees_composite_index.sql b/migrations/018_fix_assignees_composite_index.sql
new file mode 100644
index 0000000..2d40215
--- /dev/null
+++ b/migrations/018_fix_assignees_composite_index.sql
@@ -0,0 +1,10 @@
+-- Migration 018: Fix composite index on issue_assignees
+-- Migration 005 created idx_issue_assignees_username(username) as single-column.
+-- Migration 017 attempted to recreate as (username, issue_id) but IF NOT EXISTS
+-- silently skipped it. Drop and recreate with the correct composite columns.
+
+DROP INDEX IF EXISTS idx_issue_assignees_username;
+CREATE INDEX idx_issue_assignees_username ON issue_assignees(username, issue_id);
+
+INSERT INTO schema_version (version, applied_at, description)
+VALUES (18, strftime('%s', 'now') * 1000, 'Fix composite index on issue_assignees');
diff --git a/src/core/db.rs b/src/core/db.rs
index 3c2a143..5858c7b 100644
--- a/src/core/db.rs
+++ b/src/core/db.rs
@@ -53,6 +53,10 @@ const MIGRATIONS: &[(&str, &str)] = &[
         include_str!("../../migrations/016_mr_file_changes.sql"),
     ),
     ("017", include_str!("../../migrations/017_who_indexes.sql")),
+    (
+        "018",
+        include_str!("../../migrations/018_fix_assignees_composite_index.sql"),
+    ),
 ];
 
 pub fn create_connection(db_path: &Path) -> Result<Connection> {
diff --git a/src/core/timeline.rs b/src/core/timeline.rs
index 2f41310..b8632b4 100644
--- a/src/core/timeline.rs
+++ b/src/core/timeline.rs
@@ -25,6 +25,7 @@ pub struct TimelineEvent {
 impl PartialEq for TimelineEvent {
     fn eq(&self, other: &Self) -> bool {
         self.timestamp == other.timestamp
+            && self.entity_type == other.entity_type
             && self.entity_id == other.entity_id
             && self.event_type == other.event_type
     }
@@ -42,6 +43,7 @@ impl Ord for TimelineEvent {
     fn cmp(&self, other: &Self) -> Ordering {
         self.timestamp
             .cmp(&other.timestamp)
+            .then_with(|| self.entity_type.cmp(&other.entity_type))
             .then_with(|| self.entity_id.cmp(&other.entity_id))
             .then_with(|| self.event_type.cmp(&other.event_type))
     }
diff --git a/src/ingestion/discussions.rs b/src/ingestion/discussions.rs
index f406c10..c3db777 100644
--- a/src/ingestion/discussions.rs
+++ b/src/ingestion/discussions.rs
@@ -96,16 +96,6 @@ async fn ingest_discussions_for_issue(
         result.discussions_fetched += 1;
 
         let payload_bytes = serde_json::to_vec(&gitlab_discussion)?;
-        let payload_id = store_payload(
-            conn,
-            StorePayloadOptions {
-                project_id: Some(local_project_id),
-                resource_type: "discussion",
-                gitlab_id: &gitlab_discussion.id,
-                json_bytes: &payload_bytes,
-                compress: config.storage.compress_raw_payloads,
-            },
-        )?;
 
         let normalized = transform_discussion(
             &gitlab_discussion,
@@ -115,6 +105,17 @@ async fn ingest_discussions_for_issue(
 
         let tx = conn.unchecked_transaction()?;
 
+        let payload_id = store_payload(
+            &tx,
+            StorePayloadOptions {
+                project_id: Some(local_project_id),
+                resource_type: "discussion",
+                gitlab_id: &gitlab_discussion.id,
+                json_bytes: &payload_bytes,
+                compress: config.storage.compress_raw_payloads,
+            },
+        )?;
+
         upsert_discussion(&tx, &normalized, payload_id)?;
 
         let local_discussion_id: i64 = tx.query_row(