diff --git a/hub/src/db/scheduled-tasks-dal.ts b/hub/src/db/scheduled-tasks-dal.ts
index 5fe92d5..47009e3 100644
--- a/hub/src/db/scheduled-tasks-dal.ts
+++ b/hub/src/db/scheduled-tasks-dal.ts
@@ -325,10 +325,10 @@ export async function insertRunV2(input: {
   started_at?: Date | null
   finished_at?: Date | null
 }): Promise<ScheduledTaskRun> {
-  const startedAt =
-    input.started_at !== undefined
-      ? input.started_at
-      : input.status === 'pending' ? null : new Date()
+  // started_at is NOT NULL in the schema. Always default to now() when the
+  // caller doesn't pass one (or passes null/undefined explicitly). The legacy
+  // pending=>null branch caused cron fires to fail the insert (#PR49 regression).
+  const startedAt = input.started_at ?? new Date()
   const finishedAt = input.finished_at ?? null
   const rows = await sql<ScheduledTaskRun[]>`
     INSERT INTO scheduled_task_runs (
diff --git a/hub/src/db/schema.sql b/hub/src/db/schema.sql
index 14eb831..578b1ea 100644
--- a/hub/src/db/schema.sql
+++ b/hub/src/db/schema.sql
@@ -229,6 +229,11 @@ ALTER TABLE scheduled_task_runs ADD COLUMN IF NOT EXISTS output_snippet TEXT;
 ALTER TABLE scheduled_task_runs ADD COLUMN IF NOT EXISTS triggered_by_run_id TEXT REFERENCES scheduled_task_runs(id) ON DELETE SET NULL;
 ALTER TABLE scheduled_task_runs ADD COLUMN IF NOT EXISTS created_at TIMESTAMPTZ NOT NULL DEFAULT now();
 
+-- Belt-and-suspenders for the cron-fire regression: ensure started_at always
+-- has a DB-side default so an accidentally-omitted JS value never trips the
+-- NOT NULL constraint. Idempotent.
+ALTER TABLE scheduled_task_runs ALTER COLUMN started_at SET DEFAULT now();
+
 CREATE INDEX IF NOT EXISTS idx_scheduled_runs_task_scheduled
   ON scheduled_task_runs(task_id, scheduled_for DESC);
 CREATE INDEX IF NOT EXISTS idx_scheduled_runs_user_scheduled
diff --git a/hub/test/insert-run-started-at.test.ts b/hub/test/insert-run-started-at.test.ts
new file mode 100644
index 0000000..77408a9
--- /dev/null
+++ b/hub/test/insert-run-started-at.test.ts
@@ -0,0 +1,82 @@
+/**
+ * Regression: PR #49 made started_at default to null when status='pending',
+ * which violates the NOT NULL column constraint. Every cron fire was failing
+ * in prod. insertRunV2 must ALWAYS pass a non-null started_at to SQL.
+ */
+import { describe, it, expect, mock, beforeEach } from 'bun:test'
+
+// Capture the values passed to the tagged-template `sql` call.
+let captured: any[] = []
+
+mock.module('../src/db/postgres.ts', () => {
+  const sql: any = (strings: TemplateStringsArray, ...values: any[]) => {
+    captured.push({ strings: [...strings], values })
+    // INSERT ... RETURNING * — return a fake row so insertRunV2 resolves.
+    return Promise.resolve([
+      { id: 'run_test', status: 'pending', started_at: new Date() },
+    ])
+  }
+  return { sql, default: sql }
+})
+
+const { insertRunV2 } = await import('../src/db/scheduled-tasks-dal.ts')
+
+describe('insertRunV2 started_at safety', () => {
+  beforeEach(() => {
+    captured = []
+  })
+
+  it('passes a non-null Date for started_at when status=pending and started_at omitted', async () => {
+    await insertRunV2({
+      task_id: 't1',
+      user_id: 'u1',
+      status: 'pending',
+      scheduled_for: new Date(),
+      target_kind: 'agent',
+    })
+    expect(captured.length).toBeGreaterThan(0)
+    const vals = captured[0].values
+    // started_at sits between triggered_by_run_id and finished_at in the
+    // INSERT VALUES clause. Find any Date value that isn't scheduled_for.
+    const dates = vals.filter((v: any) => v instanceof Date)
+    expect(dates.length).toBeGreaterThanOrEqual(2) // scheduled_for + started_at
+    // None of the date values should be null/undefined.
+    for (const v of vals) {
+      if (v === null || v === undefined) continue
+      // ok
+    }
+    // Specifically: no Date slot in values is null.
+    const allDates = vals.filter(
+      (v: any) => v instanceof Date || v === null || v === undefined,
+    )
+    // started_at slot must not be null
+    expect(dates.some((d: Date) => d instanceof Date)).toBe(true)
+  })
+
+  it('passes a non-null Date for status=success path', async () => {
+    await insertRunV2({
+      task_id: 't1',
+      user_id: 'u1',
+      status: 'success',
+      scheduled_for: new Date(),
+      target_kind: 'agent',
+    })
+    const vals = captured[0].values
+    const dates = vals.filter((v: any) => v instanceof Date)
+    expect(dates.length).toBeGreaterThanOrEqual(2)
+  })
+
+  it('honors caller-provided started_at when given', async () => {
+    const explicit = new Date('2026-01-01T00:00:00Z')
+    await insertRunV2({
+      task_id: 't1',
+      user_id: 'u1',
+      status: 'pending',
+      scheduled_for: new Date(),
+      target_kind: 'agent',
+      started_at: explicit,
+    })
+    const vals = captured[0].values
+    expect(vals.some((v: any) => v instanceof Date && v.getTime() === explicit.getTime())).toBe(true)
+  })
+})