diff --git a/internal/db/migrations/0001_cloud_core_skeleton.sql b/internal/db/migrations/0001_cloud_core_skeleton.sql
index 8dff62e7..d56be2d0 100644
--- a/internal/db/migrations/0001_cloud_core_skeleton.sql
+++ b/internal/db/migrations/0001_cloud_core_skeleton.sql
@@ -294,6 +294,25 @@ CREATE TABLE IF NOT EXISTS workbench_trace_events (
 );
 CREATE INDEX IF NOT EXISTS idx_workbench_trace_events_trace_seq ON workbench_trace_events(trace_id, source_seq, projected_seq, id);
 CREATE INDEX IF NOT EXISTS idx_workbench_trace_events_session_seq ON workbench_trace_events(session_id, source_seq, projected_seq, id);
+WITH traces_needing_resequence AS (
+  SELECT trace_id
+  FROM workbench_trace_events
+  WHERE trace_id IS NOT NULL
+  GROUP BY trace_id
+  HAVING COUNT(*) <> COUNT(DISTINCT projected_seq)
+), ranked_trace_events AS (
+  SELECT
+    workbench_trace_events.id,
+    (ROW_NUMBER() OVER (PARTITION BY workbench_trace_events.trace_id ORDER BY workbench_trace_events.occurred_at, workbench_trace_events.id))::integer AS durable_projection_seq
+  FROM workbench_trace_events
+  INNER JOIN traces_needing_resequence
+    ON traces_needing_resequence.trace_id = workbench_trace_events.trace_id
+)
+UPDATE workbench_trace_events AS existing_trace_events
+SET projected_seq = ranked_trace_events.durable_projection_seq
+FROM ranked_trace_events
+WHERE existing_trace_events.id = ranked_trace_events.id
+  AND existing_trace_events.projected_seq IS DISTINCT FROM ranked_trace_events.durable_projection_seq;
 CREATE UNIQUE INDEX IF NOT EXISTS idx_workbench_trace_events_trace_source_event ON workbench_trace_events(trace_id, source_event_id) WHERE source_event_id IS NOT NULL;
 CREATE UNIQUE INDEX IF NOT EXISTS idx_workbench_trace_events_trace_projected_seq ON workbench_trace_events(trace_id, projected_seq);
 
diff --git a/internal/db/schema.test.ts b/internal/db/schema.test.ts
index 528715f7..d6d176c3 100644
--- a/internal/db/schema.test.ts
+++ b/internal/db/schema.test.ts
@@ -84,6 +84,10 @@ test("initial migration declares Workbench fact backfill sources", async () => {
   assert.ok(traceBackfillMatch, "missing workbench_trace_events idempotent backfill");
   assert.match(traceBackfillMatch[0], /ROW_NUMBER\(\) OVER \(PARTITION BY trace_id ORDER BY occurred_at, id\)/u);
   assert.match(traceBackfillMatch[0], /durable_projection_seq/u);
+  const traceResequenceMatch = sql.match(/WITH traces_needing_resequence AS \([\s\S]*?CREATE UNIQUE INDEX IF NOT EXISTS idx_workbench_trace_events_trace_projected_seq/u);
+  assert.ok(traceResequenceMatch, "missing workbench_trace_events projected_seq resequence before unique index");
+  assert.match(traceResequenceMatch[0], /COUNT\(\*\) <> COUNT\(DISTINCT projected_seq\)/u);
+  assert.match(traceResequenceMatch[0], /UPDATE workbench_trace_events AS existing_trace_events/u);
 });
 
 test("protocol record guards catch schema drift before runtime writes", () => {