chore(wolf): checkpoint buglog.json (1027 bugs)

.wolf/buglog.json

@@ -18737,6 +18737,27 @@
       "related_bugs": [],
       "occurrences": 1,
       "last_seen": "2026-08-25T16:30:00Z"
+    },
+    {
+      "id": "bug-1686",
+      "timestamp": "2026-08-25T16:24:00Z",
+      "error_message": "User-reported live crash (build.dbg, commit b040dfc0 -- AFTER the bug-1685 double-free fix landed, so this is a distinct, separate crash): xce_scheduler SIGSEGV in fcfs_cursor_enter_queue (src/scheduler/src/plugins/builtin_fcfs.c:673), called from builtin_fcfs_next_job (builtin_fcfs.c:810) <- sched_job_picker (scheduler.c:118) <- picker thread. Crash line 673 is the NULL branch of a ternary expression. queue_item=0x7db7d0000000 -- a suspiciously round address (large power-of-2-aligned), possibly a corrupted/uninitialized pointer rather than a normal heap allocation. Core captured from a live 3-node HA deployment run (--peers ctrl-1/ctrl-2/ctrl-3, -vvv).",
+      "file": "src/scheduler/src/plugins/builtin_fcfs.c",
+      "root_cause": "Not yet root-caused. Needs a source read of fcfs_cursor_enter_queue() (builtin_fcfs.c ~line 640-680) and its caller builtin_fcfs_next_job() (~line 780-815) to determine what queue_item=0x7db7d0000000 actually is (a cursor into fcfs_plugin_data_t's ordq_t queues/pendJobs structures per this plugin's own design -- see .wolf/cerebrum.md and scheduler/CLAUDE.md for the builtin_fcfs architecture) and whether it's genuinely corrupted (heap corruption elsewhere manifesting here, matching the same general class of bug as bug-1685) or a real-but-wrong pointer from an iteration/locking bug specific to this function.",
+      "fix": "Not yet fixed -- investigating.",
+      "tags": [
+        "scheduler",
+        "builtin_fcfs",
+        "crash",
+        "sigsegv",
+        "live-deployment",
+        "picker-plugin"
+      ],
+      "related_bugs": [
+        "bug-1685"
+      ],
+      "occurrences": 1,
+      "last_seen": "2026-08-25T16:24:00Z"
     }
   ]
 }