feat(ha-single-leader-role): WAL_NOOP entry type — enum + apply no-op + RETAIN classify (task 1.2)

.kiro/specs/ha-single-leader-role/tasks.md

@@ -11,7 +11,7 @@
   - Observable completion: build succeeds with the new test file; all new cases FAIL (red) — `WAL_NOOP` does not exist yet
   - _Requirements: 2.1_
 
-- [ ] 1.2 Implement WAL_NOOP to green
+- [x] 1.2 Implement WAL_NOOP to green
   - Add `WAL_NOOP = 40` to `wal_entry_type` (src/include/wal_types.h:44-58) with comment: internal, empty payload, replay no-op, appended only at promotion; value stays below `WAL_ENTRY_TYPE_MAX` (100, src/include/config.h:80) so standbys LSN-advance and ACK it via the existing common path
   - Add explicit `case WAL_NOOP: break;` to `apply_wal_entry`'s type switch (persist.c:728-765 anchor); add the `WAL_NOOP → WAL_MODE_RETAIN` row to `wal_classify` (the row barrier-rollout pre-declared)
   - Observable completion: all task 1.1 tests PASS; barrier-rollout's classification totality test still PASSES

src/controller/persist.c

@@ -764,6 +764,12 @@ int apply_wal_entry(persist_t* p, const wal_entry_hdr_t* hdr, const void* payloa
         }
         break;
 
+    case WAL_NOOP:
+        /* Internal promotion no-op: empty payload, no entity restore, no
+         * hooks. The common-path current_lsn advance (above) is its only
+         * effect — recognised explicitly here rather than via default. */
+        break;
+
     default:
         break;
     }
@@ -1160,6 +1166,11 @@ wal_commit_mode_t wal_classify(uint32_t wal_type, int detail)
          * realized by the handler barrier in do_jobcontrol_op
          * (research.md §2 call-site verification). */
         return WAL_MODE_RETAIN;
+    case WAL_NOOP:
+        /* internal promotion no-op — replicated like any committed entry,
+         * retained until committed (ha-commit-barrier-rollout pre-declared
+         * row: promotion | internal | RETAIN; guard forces classification) */
+        return WAL_MODE_RETAIN;
     case WAL_CHECKPOINT:
         /* local segment marker — never replicated, by design */
         return WAL_MODE_LOCAL;

src/include/wal_types.h

@@ -54,5 +54,6 @@ typedef enum {
     WAL_JOB_PREASON = 10,
     WAL_QUEUE_CTRL  = 20,
     WAL_WORKER_CTRL = 30,
+    WAL_NOOP        = 40,  /* Internal: empty payload, replay no-op; appended only at promotion */
     WAL_CHECKPOINT  = 100, /* Local WAL marker only — never replicated */
 } wal_entry_type;