feat(ha-entity-snapshots): log legacy-vs-entity fallback in local boot recovery (task 8.1)

persist_recover's local snapshot load passed NULL for out_entities_restored,
so a rolling-upgrade restart against a pre-feature checkpoint had no
observability parity with the wire receive path's (task 6.1) INFO log.
Mirror the same conditional logging here; no behavior change, WAL replay
in Step 3 still applies unconditionally either way.

Live-verified in a 3-node cluster: planted a hand-crafted 16-byte legacy
sentinel as ctrl-1's own checkpoint file, restarted all 3 — no crash, INFO
log fired, ctrl-1 was elected primary serving the full 37-job list, and
walcompare confirmed all 3 members' committed prefixes (LSN 1..49) are
byte-identical.

.kiro/specs/ha-entity-snapshots/tasks.md

@@ -137,8 +137,8 @@
     lands, then re-run with a forced empty-rejoin round to get a true signal on this spec's own
     entity-restore correctness._
 
-- [ ] 8. Validation: rolling-upgrade compatibility
+- [x] 8. Validation: rolling-upgrade compatibility
-- [ ] 8.1 Verify a pre-feature checkpoint file is handled safely by the new binary in a live
+- [x] 8.1 Verify a pre-feature checkpoint file is handled safely by the new binary in a live
       cluster
   - Plant a checkpoint file in the legacy (position-only) format, start a member on the upgraded
     binary against it, and observe its behavior
@@ -147,6 +147,18 @@
     completeness
   - _Requirements: 5.1, 5.2_
   - _Depends: 6.1_
+  - (8.1) `persist_recover`'s local boot-time snapshot load (persist.c ~2790) passed `NULL` for
+    `out_entities_restored` -- it had no observability parity with the wire receive path's
+    (`ha_handle_snapshot_chunk`, task 6.1) legacy-vs-entity-bearing INFO log. Added the same
+    conditional INFO logging at this call site (small, additive, no behavior change -- WAL replay
+    in Step 3 still applies unconditionally either way). Live-verified: planted a hand-crafted
+    16-byte legacy sentinel (`XCESNAP\0` + LE checkpoint_lsn=1, no entity frames) as ctrl-1's own
+    `snap-0000000000000001.capnp` in a 3-node cluster (reusing the ha-entity-snap soak deploy,
+    WAL segments left intact), restarted all 3. ctrl-1: no crash, logged
+    "persist_recover: ... is a legacy position-only checkpoint ... continuing via normal WAL
+    replay", was elected primary, served the full 37-job list, and `walcompare` reported all 3
+    members' committed prefixes (LSN 1..49) byte-identical -- confirms full committed consistency
+    reached via ordinary WAL replay, no false-positive completeness.
 
 ## Implementation Notes
 - (1.1) Test fixture `snapent_make`/`snapent_teardown` lives in `test_persist_snapshot_entities.c`; seeded jobs currently carry only jobid+state+an all-zeroed submit. Task 2.1's "field-identical round-trip" assertion needs richer submit-payload seeding (e.g. non-zero cmdline/user/queue in `xce_job_submit_t`) to be a meaningful field-by-field comparison — extend `snapent_seed_jobs`, do not re-seed separately.

src/controller/persist.c

@@ -2789,16 +2789,30 @@ int persist_recover(persist_t* p)
 
     /* --- Step 2: load snapshot (if any) --- */
     if (snap_lsn > 0 && snap_file[0] != '\0') {
-        /* Local recovery doesn't need the entities-restored indicator: the
+        /* Local recovery doesn't need the entities-restored indicator to
-         * WAL replay in Step 3 applies everything above checkpoint_lsn
+         * decide behavior: the WAL replay in Step 3 applies everything
-         * regardless, unchanged by ha-entity-snapshots. */
+         * above checkpoint_lsn regardless, unchanged by ha-entity-snapshots.
-        int rc = load_snapshot(p, snap_file, snap_lsn, NULL);
+         * It IS consumed for observability parity with the wire receive
+         * path (ha_handle_snapshot_chunk, task 6.1) — a rolling-upgrade
+         * restart against a pre-feature (legacy, position-only) local
+         * checkpoint is an expected rollout state, not an error. */
+        bool entities_restored = false;
+        int rc = load_snapshot(p, snap_file, snap_lsn, &entities_restored);
         if (rc != 0) {
             ERROR("persist_recover: failed to load snapshot %s: %s",
                   snap_file, strerror(-rc));
             return rc;
         }
         /* checkpoint_lsn and current_lsn set by load_snapshot */
+        if (entities_restored) {
+            INFO("persist_recover: snapshot %s loaded lsn=%" PRIu64
+                 " with full job/queue entity restoration", snap_file,
+                 p->checkpoint_lsn);
+        } else {
+            INFO("persist_recover: snapshot %s lsn=%" PRIu64 " is a legacy "
+                 "position-only checkpoint (no entity content) — continuing "
+                 "via normal WAL replay", snap_file, p->checkpoint_lsn);
+        }
     }
 
     /* --- Step 3: replay WAL entries after checkpoint_lsn --- */