---
id: "bug-1878"
status: "fixed"
status_updated: "2026-09-28"
status_note: ""
component: "controller"
severity: "wrong-result"
timestamp: "2026-09-28T07:11:38Z"
last_seen: "2026-09-28T07:11:38Z"
occurrences: 1
files: ["src/controller/ctrlstatus.c"]
tags: ["controller", "ctrlstatus", "ha", "display"]
related: ["bug-1819"]
fix_commits: ["aa7fc65a"]
gitea_issue: 329
gitea_synced_status: "fixed"
gitea_synced_hash: "b6e3f549c655"
---

# bug-1878: ctrlstatus reports appliedLsn 0 on the primary (standby-only counter)

## Description
**Observed:**
```
xce/client>ctrlstatus
Primary: ctrl-1
...
answered by ctrl-1 (primary)
term: 2
committedLsn: 4900
appliedLsn: 0
```
(pc13v, 2026-09-28 14:56; locally: committedLsn 2, appliedLsn 0)
**Expected:** the primary's real apply position, next to its committed position.
**Impact:** every primary's ctrlstatus says it has applied nothing, which reads like a stalled apply pump; operators and scripts comparing applied vs committed get a false alarm. The data path itself is fine.
**Found by:** user running xce_test ctrlstatus on pc13v after the bug-1872..1877 retest

## Environment
- OS: no /etc/os-release; Docker container; NixOS kernel; kernel Linux 6.18.33 x86_64
- libc: glibc 2.42-47 (interpreter /nix/store/wb6rhpznjfczwlwx23zmdrrw74bayxw4-glibc-2.42-47/lib/ld-linux-x86-64.so.2)
- Toolchain: gcc (GCC) 15.2.0, meson 1.9.1
- Build: asan (xce.build)
- Code: scheduler-framework @ 44173f74 (controller unchanged since; pc13v ran 4c134127)
- Deployment: local 3-node HA (localhost:9991-9993, src/tools/deploy-ha.sh, nodes started 1 s apart by start-all.sh, xcecd_virtual) on this dev host; first seen on pc13v: NixOS 26.05, kernel 6.18.33, glibc 2.42-47, debug build, 3-node HA (ctrl-1..3, localhost:9901-9903) + scheduler + apiserver + real root xcecd, /tmp/xce-ha-deploy, 2026-09-28 14:47 +0800

## Reproduction
1. Deploy and start a 3-node HA cluster (`/xce-deploy-ha`, then `scripts/start-all.sh`)
2. `xce_test --norc`, then `set masters ctrl1=localhost:9991,ctrl2=localhost:9992,ctrl3=localhost:9993`, `client`, `ctrlstatus`
- Frequency: deterministic (any primary)
- Evidence: the ctrlstatus output quoted above (pc13v, pasted in the user's report) and the local run, 2026-09-28

## Root cause
ctrlstatus_fill() (src/controller/ctrlstatus.c:178) sets appliedLsn from ha->applied_lsn for every role. That counter (ha.h:161, "Standby: last applied WAL LSN") is only advanced when a standby applies replicated entries; ha_init() zeroes it and nothing advances it on a primary. The primary's apply cursor is persist->last_applied_lsn, which ctrlstatus never reads. The two use different conventions: ha->applied_lsn is the NEXT lsn to apply (entry->lsn+1, ha.h:969), persist->last_applied_lsn the last applied entry -- a fix has to report one convention for both roles.

## Fix
ctrlstatus_fill() (src/controller/ctrlstatus.c) reports a primary's appliedLsn from persist->last_applied_lsn (the last entry applied, never above committedLsn); a standby still reports ha->applied_lsn, as the spec defines. The existing primary fixture set ha.applied_lsn=42 on a primary, a state that never occurs live -- it now uses persist.last_applied_lsn. The controller-status design doc's "already correct in every role" note is corrected.

## Verification
- Test: test_ctrlstatus_primary_reports_its_apply_cursor in src/controller/testsuite/test_ctrlstatus.c (pc13v's values): RED before the fix (Expected 4900 Was 0), GREEN after
- Suites: controller suite 1256/0 (asan); test_ha_failover_prevote 11/0, test_ha_liveness 38/0, test_ha_failover 8/0, test_ctrlstatus 23/0
- Live: HA soaks on aa7fc65a's tree: sequential 6 rounds PASS (21 jobs, zero job loss, all 3 nodes led); chaotic 6 rounds PASS (zero committed divergence, zero committed job loss); pc13v retest pending; ctrlstatus on the soak clusters not captured separately

## References
- Related: bug-1819 (ctrlstatus_fill stale-slot bug, same function)
- Docs: .kiro/specs/controller-status/requirements.md (Req 6.2 commit/apply positions; lines 102-107)