feat(ha-convergence-recovery): self-restart primitive + demotion convergence (task 2.2)

src/controller/ha.h

@@ -273,6 +273,26 @@ char **controller_saved_argv(void);
  */
 int ha_self_restart(cluster_t *c);
 
+/*
+ * ha_schedule_demotion_convergence: schedule the one-shot delaymgr task that
+ * truncates above committed_lsn (Req 1.2), WARN-logs the discarded range
+ * (Req 1.5), and self-restarts (Req 1.3).  Called from raft_cb_become_follower's
+ * was-PRIMARY branch AFTER the persistence hooks are disabled inline (Req 1.1),
+ * so all file I/O and the exec run off the become-follower callback thread (D1).
+ * Returns 0 on success, negative on alloc/schedule failure (suffix is then
+ * reconciled by rejoin reconciliation at the next join).
+ */
+int ha_schedule_demotion_convergence(cluster_t *c);
+
+#ifdef XCE_TESTING
+/*
+ * ha_demotion_convergence_fn: the delaymgr task body — exposed under XCE_TESTING
+ * only so the demotion-convergence suite can reference its contract; the test
+ * fixture drives the queued task through its stored entry pointer.
+ */
+int ha_demotion_convergence_fn(void *arg);
+#endif
+
 
 /* ── Redirect helpers used by join.c ──────────────────────── */