huskies: merge 1175 bug Flaky tests intermittently fail merge gates

server/src/agents/pool/pipeline/merge/runner.rs

@@ -32,7 +32,19 @@ impl AgentPool {
     /// Called at the top of [`start_merge_agent_work`] to unblock retries,
     /// and also by the periodic background reaper in the tick loop so stale
     /// entries are cleaned up even when no new merge is triggered.
+    ///
+    /// A job's `server_start` round-trips through JSON text (see
+    /// [`encode_server_start_time`]/[`decode_server_start_time`]), and
+    /// `serde_json`'s float parser is not guaranteed bit-exact for
+    /// high-precision Unix timestamps — it can decode a value a couple of
+    /// ULPs below the original. Comparing with a bare `<` against a
+    /// freshly-read `current_boot` would then occasionally treat a job
+    /// written by *this very server instance* as belonging to a previous
+    /// one. Real server restarts are always seconds apart at minimum, so a
+    /// generous tolerance absorbs that noise without weakening genuine
+    /// stale-boot detection.
     pub(crate) fn reap_stale_merge_jobs(&self) {
+        const STALE_TOLERANCE_SECS: f64 = 1.0;
         if let Some(jobs) = crate::crdt_state::read_all_merge_jobs() {
             let current_boot = server_start_time();
             for job in jobs {
@@ -40,7 +52,7 @@ impl AgentPool {
                     continue;
                 }
                 let stale = match decode_server_start_time(job.error.as_deref()) {
-                    Some(t) => t < current_boot,
+                    Some(t) => t < current_boot - STALE_TOLERANCE_SECS,
                     None => true, // Legacy (pid-encoded) or malformed: stale
                 };
                 if stale {

server/src/agents/pool/pipeline/merge/tests.rs

@@ -113,6 +113,22 @@ async fn stale_running_merge_job_is_cleared_and_retry_succeeds() {
         result.is_ok(),
         "start_merge_agent_work must succeed after stale Running job is cleared; got: {result:?}"
     );
+
+    // start_merge_agent_work spawns the actual pipeline as a background
+    // tokio task and returns immediately. Wait for it to reach a terminal
+    // state before the test ends: otherwise the task keeps running after
+    // `_serial` is released and can still be touching CRDT state
+    // (write_merge_job / delete_merge_job) while the next merge-pipeline
+    // test has already called init_for_test(), corrupting that test's
+    // thread-local state.
+    loop {
+        tokio::time::sleep(std::time::Duration::from_millis(50)).await;
+        if let Some(job) = pool.get_merge_status("77_story_stale")
+            && !matches!(job.status, MergeJobStatus::Running)
+        {
+            break;
+        }
+    }
 }
 
 // ── story 852: periodic background reaper ────────────────────────────────