test(ha-convergence-recovery): RED ACK-driven catch-up continuation tests + seam (task 4.1)

src/controller/ha_convergence.c

@@ -374,3 +374,33 @@ void cluster_apply_ctrlhello_reply(cluster_t *c, uint64_t committed_lsn,
     /* Req 2.1–2.3: reconcile a log that runs ahead of the cluster boundary. */
     (void)ha_rejoin_reconcile(c, committed_lsn);
 }
+
+#ifdef XCE_TESTING
+/* ───────────────────────────────────────────────────────────────────────────
+ * RED scaffold — ha-convergence-recovery task 4.1 (replaced by task 4.2 GREEN).
+ *
+ * ha_walack_continuation_for_test stands in for the post-ACK decision that the
+ * walAck branch of repl_ack_decode_and_dispatch (ha.c) must perform after
+ * repl_on_ack (D6): derive target = max(committed_lsn, last_written); when the
+ * standby is still behind target, schedule exactly one catch-up continuation
+ * (single-flight via ha.catchup_inflight[peer_idx]); at/above target call
+ * repl_complete_catchup to re-include the standby (Req 7.1).
+ *
+ * THIS SCAFFOLD INTENTIONALLY DOES NOTHING beyond recording that the ACK was
+ * observed (it mirrors the current production walAck branch, which only calls
+ * repl_on_ack).  It does NOT schedule a continuation and does NOT call
+ * repl_complete_catchup — so the continuation / single-flight / parity tests in
+ * test_convergence_verification.c FAIL (RED) until task 4.2 implements the real
+ * decision here and wires it into the production walAck branch.
+ * ─────────────────────────────────────────────────────────────────────────── */
+int ha_walack_continuation_for_test(cluster_t *c, void *ep, int peer_idx,
+                                    uint64_t acked_lsn)
+{
+    /* RED scaffold — task 4.2 replaces this body with the D6 decision. */
+    (void)c;
+    (void)ep;
+    (void)peer_idx;
+    (void)acked_lsn;
+    return 0;
+}
+#endif /* XCE_TESTING */