diff --git a/crates/cm-api/src/podcast.rs b/crates/cm-api/src/podcast.rs
index 0822dcd..2b465da 100644
--- a/crates/cm-api/src/podcast.rs
+++ b/crates/cm-api/src/podcast.rs
@@ -699,6 +699,12 @@ mod live {
 
 // ── Rendering a finished mission into an episode ──────────────────────
 
+/// How long a tombstone stands before the sweep tries that mission again.
+///
+/// Long enough that a dead end is not retried every two minutes; short
+/// enough that a deploy which fixes the cause recovers the same day.
+const RETRY_TOMBSTONE_AFTER: &str = "6 hours";
+
 /// Where a mission's script lives inside its checkout.
 pub fn script_path(date: &str) -> String {
     format!("ContinuousResearch/{date}/script.md")
@@ -754,16 +760,35 @@ pub async fn render_pending(
     backend: &dyn AudioBackend,
 ) -> Result<usize, String> {
     use sqlx::Row;
+    // A mission with no episode, or one whose last attempt was a TOMBSTONE
+    // old enough to be worth trying again.
+    //
+    // Tombstones used to be permanent: `NOT EXISTS (podcast_episodes)` meant
+    // that once a day gave up it could never be reconsidered, so a fix
+    // shipped afterwards recovered nothing. Mission 01a0c9c4 was tombstoned
+    // four minutes before the build that could have rendered it rolled, and
+    // stayed silent on a script that was sitting on a branch the whole time.
+    //
+    // The backoff is what keeps this from becoming the every-two-minutes
+    // churn that the no-turns tombstone was added to stop: at most one
+    // retry per mission per window, because `record_unrenderable_because`
+    // refreshes `created_at` on each attempt.
     let rows = sqlx::query(
         "SELECT m.id, m.workspace_id, m.title
            FROM missions m
+           LEFT JOIN podcast_episodes e ON e.mission_id = m.id
           WHERE m.template_kind = $1
             AND m.status IN ('completed', 'failed')
-            AND NOT EXISTS (SELECT 1 FROM podcast_episodes e WHERE e.mission_id = m.id)
+            AND (
+                  e.mission_id IS NULL
+               OR (e.rendered_by LIKE 'unrenderable%'
+                   AND e.created_at < now() - $2::interval)
+            )
           ORDER BY m.completed_at DESC NULLS LAST
           LIMIT 3",
     )
     .bind(crate::continuous_research::TEMPLATE_KIND)
+    .bind(RETRY_TOMBSTONE_AFTER)
     .fetch_all(pool)
     .await
     .map_err(|e| format!("select missions to render: {e}"))?;
@@ -1021,7 +1046,8 @@ async fn record_unrenderable_because(pool: &sqlx::PgPool, mission_id: uuid::Uuid
               duration_secs, rendered_by, script_sha)
          SELECT $1, m.workspace_id, m.id, '', m.title, '', 0, 0, $3, ''
            FROM missions m WHERE m.id = $2
-         ON CONFLICT (mission_id) DO NOTHING",
+         ON CONFLICT (mission_id) DO UPDATE
+            SET rendered_by = EXCLUDED.rendered_by, created_at = now()",
     )
     .bind(uuid::Uuid::now_v7())
     .bind(mission_id)