myxce/.kiro/specs/ha-config-bootstrap/research.md

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Cross-Spec Gap Audit (2026-06-03)

Triggered by: /kiro-validate-gap ha-config-bootstrap election-iomgr-refactor, check am_i_primary() still be used? Scope: confirm cross-spec coverage status; answer am_i_primary() question definitively.

Analysis Summary

• ha-config-bootstrap remains at ~95% (all unit tasks done; tasks 11.1–11.5 are manual integration tests).
• election-iomgr-refactor is 100% complete and already marked implemented.
• The two specs are consistent and non-overlapping in implementation: election-iomgr-refactor superseded the blocking-pthread election path defined in ha-config-bootstrap, keeping all requirements satisfied through a different (better) implementation path.
• am_i_primary() question: answered — it is dead code, safe to delete, but not harmful to leave.

am_i_primary() Status

What it is

am_i_primary() (ha.c:869) is the original LSF priority-based election probe — it spawns one pthread per peer and self-promotes if no higher-priority peer responds before a deadline. It was the pre-Raft election mechanism.

Is it still called?

No. Confirmed by grep:

• myapp.c: comment at line 48 explicitly says am_i_primary_quorum (the intermediate Raft replacement) was removed in Req 9.3. am_i_primary() is never referenced in myapp.c.
• cluster.c line 1015: The line /* Determine initial role based on am_i_primary() result set by myapp_run */ is a stale comment — the actual code underneath calls ha_is_primary(&c->ha) (the atomic role check), not am_i_primary(). The comment is a lie left over from the old startup sequence.
• ha.c: The function is defined but has no callers in production code. The only cross-file reference to am_i_primary (not am_i_primary_quorum) in non-test code is the cluster.c comment above.

What the tests use

• test_ha_role.c (lines 241–396): three test cases test am_i_primary() directly — these are legacy P1-6 tests covering the old priority-based election. They still pass because the function body is intact.
• test_ha_bootstrap_support.c and test_ha_election.c: both define stubs for am_i_primary_quorum (the intermediate function, not am_i_primary), used to isolate the quorum election logic under test.

Decision: can am_i_primary() be deleted?

Yes — safe to delete in a cleanup pass. However:

• The three test cases in test_ha_role.c would also need to be deleted.
• The stale comment in cluster.c line 1015 should be updated to say "role set by ha_elect_evaluate_and_signal via vtask".
• start_heartbeat_listener() / stop_heartbeat_listener() stubs (ha.c:951-960) referenced in the same comment block can also be cleaned up.

Recommendation: Leave am_i_primary() as-is during active HA development. Mark as cleanup tech debt. Its presence does not affect correctness, ASAN, or test pass rate.

Requirement Coverage Cross-Check

The election-iomgr-refactor implemented ha_start_election_async which replaced both am_i_primary() and am_i_primary_quorum(). The ha-config-bootstrap tasks 4.3 and 9.4 originally called am_i_primary_quorum() from myapp.c — these are now superseded by ha_start_election_async. Both specs' requirements are fully met by the current codebase.

No new code needed for either spec.

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Gap Analysis — Completion Audit (2026-06-02)

Analysis date: 2026-06-02. Phase: tasks-generated. All leaf implementation tasks [x]. Purpose: verify actual codebase coverage of all 10 requirements; identify what remains before the spec can be marked implemented.

Analysis Summary

• Scope: 10 requirements across 8 implementation changes (A–H), covering Raft-style quorum election, majority-commit WAL + config replication, persistent control channels, config bootstrap, term durability, and client-side retry.
• Implementation status: ~95% complete. All 22 leaf subtasks (1.1–10.2) are implemented and verified. All 9 requirements have implementation assets in the live codebase (verified via grep audit). The parent group headers in tasks.md show [ ] only because they are section labels, not actionable tasks.
• Remaining work: Integration tests 11.1–11.5 (manual cluster validation).
• No design changes needed: The implementation already follows the approved design; xce_request_with_retry, repl_wait_majority_ack, ha_find_and_connect_to_primary, ha_persist_term, bootstrap_config_if_needed, and all 9 capnp extensions are in the live codebase.
• Recommendation: Run the 5 integration tests from manual-tests.md against a 3-node cluster, then mark the spec implemented.

Requirement-to-Asset Map — Final State

Requirement	Verified Key Assets	Status
Req 1: FSM init + dispatch gate	CTRL_INIT, CTRL_ELECTING in ha.h:59-60; ha_dispatch_gate in ha.c; ha_wait_for_heartbeat_or_timeout	✅ Implemented
Req 2: Quorum election	ha_elect_evaluate_and_signal (ha.c:1604); am_i_primary_quorum replaced by raft_start_election; handle_request_vote term/freshness gate	✅ Implemented
Req 3: Config bootstrap	bootstrap_config_if_needed, xce_probe_config_tag, defer_config_fetch — all in ha.c/config_repl.c	✅ Implemented
Req 4: Contiguous WAL + ASAN	WAL schema capnp, persist_* callbacks, SSL_CTX_free fix	✅ Implemented
Req 5: Majority-commit WAL	repl_broadcast, repl_wait_majority_ack, committed_lsn in persist_t, persist_truncate_wal_above	✅ Implemented
Req 6: Persistent control channel	ha_find_and_connect_to_primary, extended ctrlhello handler, EPOLLRDHUP failover, ha_on_primary_ctrl_fd_rdhup	✅ Implemented
Req 7: State sync	apply_wal_entry, repl_start_catchup/complete_catchup, ctrlhello + WAL catch-up flow	✅ Implemented
Req 8: Majority-commit config	OP_upgradeConfigAck handler, committed_config_tag, ha_repl_ack_received	✅ Implemented
Req 9: Voted-for persistence	ha_persist_term (ha.c:1323); ha_init restore path for ha-term.bin	✅ Implemented
Req 10: Client-side retry	xce_request_with_retry (request.c:1664); xce_retry_config_t	✅ Implemented

Remaining Gaps

Gap 1: Tasks 11.1–11.5 — Integration validation (IP = In Progress via manual-tests.md)

The manual-tests.md file contains step-by-step procedures for all 5 integration tests. They require a running 3-node cluster:

Test	What it validates	Status
11.1	Concurrent startup + config-fresh election + config replication	Manual test doc written; not yet run
11.2	Failover (RDHUP → promote → WAL survived); WAL commit under partition	Manual test doc written; not yet run
11.3	Unconfigured node bootstrap (config_tag=0)	Manual test doc written; not yet run
11.4	Config upgrade majority-commit; term durability across restart	Manual test doc written; not yet run
11.5	Full ASAN build verification	Manual test doc written; not yet run

Note: These are manual cluster tests by design. The automated hook-based unit tests in testsuite/ (tests in test_ha_bootstrap.c, test_ha_durability.c, test_p1_integration.c, test_p2_integration.c, test_p3_hardening.c, test_p3_manual_failover.c) cover the in-process logic. Tasks 11.1–11.5 validate end-to-end process behavior that the hook seams cannot reach.

Gap 2: Parent group headers in tasks.md show [ ] (Cosmetic)

Tasks 1., 2., 3., 4., 5., 6., 7., 8., 9., 10. are section grouping labels — all their child subtasks are [x]. The parent headers can be marked [x] for clarity.

Constraint: xce_request_with_retry not in lib header (known limitation)

The function lives in src/lib/request.c:1664 but is not declared in src/lib/include/xce/request.h. Callers must add extern int xce_request_with_retry(...) locally. Intentional — the libxce request.h only exposes the public API; internal retry logic is a controller-side concern.

Effort and Risk Assessment

Item	Effort	Risk	Justification
Tasks 11.1–11.5 (integration)	M (1–2 days)	Low	Procedures documented; run cluster + verify logs
Fix parent checkboxes	S (1 commit)	None	Cosmetic

Conclusion

The ha-config-bootstrap spec is functionally complete — all 10 requirements are implemented, tested, and verified at the unit level. The 5 remaining integration tests (11.1–11.5) are manual cluster validations that exercise the full system behavior. The manual-tests.md file contains all the procedures. Once these are run, the spec can be marked implemented and closed.

Generated: 2026-05-27. Branch: persistent_ha.

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Analysis Summary

• Scope: 10 requirements across 8 distinct changes (A–H). The codebase has strong foundational infrastructure (iomgr, repl slot management, WAL, SSL) but the HA election core, quorum commit, and control channel are mostly absent or stubbed.
• Largest gaps: Raft-style quorum election (Req 2) and persistent control channel with full state sync (Req 6) are full rewrites/additions with no current equivalent logic; majority-commit WAL (Req 5) requires implementing the two stub functions at the heart of replication.
• Strong reusable assets: repl_add_standby/remove/start_catchup/complete_catchup/needs_snapshot are real implementations; the SSL connect pattern (connect_ssl_raw), xorshift64 PRNG, ha_do_promote/demote, and iomgr epoll machinery are all directly reusable.
• Risk concentration: Req 2 and Req 6 carry High risk; Req 5 carries High risk due to committed_lsn cross-cutting persist_t, repl.c, and ha_state_t. The remaining requirements are Medium or Low.
• Recommended approach: Hybrid (Option A) — implement changes A→D→B→C→E→F→G→H in dependency order, writing C tests first per TDD, one atomic commit per change.

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1. Current State Investigation

1.1 HA Core (ha.h / ha.c)

ctrl_role_t enum — only two values: CTRL_PRIMARY = 0, CTRL_STANDBY = 1.
Missing: CTRL_INIT, CTRL_ELECTING (required by Req 1).

ha_state_t — current fields of interest:

Field	Status	Notes
term (_Atomic uint64_t)	Exists	Used for fencing
role (_Atomic int32_t)	Exists	Cast to ctrl_role_t
my_priority	Exists	LSF priority index — kept for compat but unused in Raft
applied_lsn (_Atomic uint64_t)	Exists	Reusable for vote freshness check
primary_host[XCE_MAXNAME_LEN]	Exists	Reusable
primary_port	Exists	Reusable
last_heartbeat (struct timespec)	Exists	Replaces with EPOLLRDHUP path in Req 6
in_catch_up (_Atomic int)	Exists	Reusable for Clarification 6 vote exclusion
jitter_seed (uint64_t)	Exists	xorshift64, directly reusable
ssl_ctx (void*)	Exists	Reusable
standby_endpoints (zarray_t*)	Exists	Superseded by per-standby fd table in Req 6
voted_for_term (uint64_t)	MISSING	Req 9
voted_for_name (char[])	MISSING	Req 9
primary_ctrl_fd (int)	MISSING	Req 6
defer_config_fetch (bool)	MISSING	Req 3
elect_ctx (_Atomic ptr)	MISSING	Req 2
last_known_committed_lsn (_Atomic uint64_t)	MISSING	Req 5
heartbeat_seen (sem_t)	MISSING	Req 1

ha_config_t — missing: commit_timeout_ms. All election fields present (election_timeout_ms, jitter_max_ms, etc.) but values tuned for LSF model.

am_i_primary() — LSF priority probe via per-peer pthreads. No quorum, no config_tag/LSN in vote, no term/voted_for persistence. Must be replaced entirely with am_i_primary_quorum().

ha_check_priority_stepdown() — permanently unreachable once term > 0; exists only for the term=0 simultaneous-boot race. Must be retired (Req 2).

ha_check_heartbeat_nocluster() — timestamp polling with configurable timeout. Replaced by EPOLLRDHUP fast path + heartbeat timeout vtask (Req 6). Function itself can be deleted.

ha_watchdog_thread() — sets failover_requested but cannot call ha_promote_to_primary() (no cluster_t). Partially functional stub. Replaced by vtask-based heartbeat monitor (Req 6).

start_heartbeat_listener() / stop_heartbeat_listener() — no-op stubs with comment "full implementation in cluster.c Task 7". Missing (Req 1).

ha_fini() — missing SSL_CTX_free(ha->ssl_ctx). ASAN-visible leak (~5 KB).

1.2 Startup Sequence (myapp.c / main.c)

myapp.c current order:

cluster_init_phase1()
initialize_openssl() + create_ssl_context()
am_i_primary()                     ← election here
load_primary_config() / fetch_config_from_primary()
cluster_init_phase2()              ← iomgr, vtaskmgr, bind+listen inside
cluster_start()                    ← more network init
cluster_run()

Bind+listen happens inside cluster_init_phase2() or cluster_start() — after election. Gap: concurrent-startup nodes probe an unbound port (Req 1).

No bootstrap_config_if_needed() — standby path goes straight to fetch_config_from_primary() post-election without checking whether local config_tag is 0 or whether peers have config. Gap (Req 3).

main.c:

• --vcpus N arg: MISSING. vcpus comes from cluster config read inside phase2. This creates a dependency that prevents vtaskmgr from running before election (Req 1, 4).
• Peer count validation: MISSING. Even-N peer lists accepted silently (Req 4).
• Cert pre-flight access() check: MISSING. Cert paths computed but SSL context created later in myapp.c, not with early-exit error in main.c (Req 4).

1.3 Replication (repl.c / repl.h)

Function	Status	Notes
repl_init / fini	Real	Lifecycle ok
repl_add_standby	Real	Slot management implemented
repl_remove_standby	Real	Implemented
repl_start_catchup	Real	Sets in_catch_up=1
repl_complete_catchup	Real	Clears in_catch_up, broadcasts cond
repl_needs_snapshot	Real	Compares standby_lsn vs oldest_wal_lsn
repl_on_ack	Real	Updates acked_lsn, signals cond
repl_trim_lsn	Real	WAL trim guard implemented
repl_broadcast	STUB	Returns 0 without sending anything (Req 5, 8)
repl_wait_ack	Partial	Waits for ANY non-catch-up standby, not majority (Req 5)
repl_wait_majority_ack	MISSING	Req 5, 8

standby_conn_t — missing pending_ack_count for backpressure (Req 5).

1.4 Persistence (persist.h / persist.c)

• current_lsn and checkpoint_lsn exist. committed_lsn — MISSING (Req 5).
• persist_wal_sync_append() uses repl_wait_ack() (any-standby) — must upgrade to repl_wait_majority_ack().
• persist_truncate_wal_above() — MISSING (Req 5, 6).
• persist_config_t.sync_timeout_ms exists — analogous to commit_timeout_ms needed for majority-commit.

1.5 Config Replication (config_repl.c)

• do_one_config_fetch() — wired (recent commit 2aae45f on branch: "wire do_one_config_fetch() — full SSL roundtrip"). Not a stub.
• bootstrap_config_if_needed() — MISSING (Req 3).
• xce_probe_config_tag() — MISSING. New lightweight RPC needed (Req 3).
• push_config_to_standbys() — declared in config_repl.h; likely fire-and-forget (no majority wait). Gap: must upgrade to majority-commit (Req 8).
• OP_probeConfigTag Cap'n Proto schema — MISSING (Req 3).
• OP_upgradeConfigAck Cap'n Proto schema — MISSING (Req 8).
• committed_config_tag — MISSING (Req 8).

1.6 Control Channel (ha.c / cluster.c)

• No persistent standby-to-primary TCP connection. Each config fetch and WAL entry opens a new SSL connection via connect_ssl_raw().
• ha_find_and_connect_to_primary() — MISSING (Req 6).
• Extended OP_ctrlHello with applied_lsn, config_tag — MISSING (Req 6).
• OP_snapshotTransfer, OP_walCatchupEntry — MISSING (Req 6).
• handle_ctrlhello() extended handler — MISSING (Req 6).
• Three-tier primary discovery — MISSING (Req 6).
• EPOLLRDHUP failover detection — MISSING (Req 6).
• Heartbeat timeout vtask replacing watchdog thread — MISSING (Req 6).

1.7 Election State Durability

• ha-term.bin file — does not exist.
• ha_persist_term() — MISSING (Req 9).
• ha_init() zeros term and has no ha-term.bin read path.

1.8 libxce Client Retry (src/lib/)

• ha_should_redirect() / ha_no_primary_known() exist in ha.c and are used by join.c.
• No transparent retry loop for XCE_ERR_NOT_READY, XCE_ERR_STANDBY, ECONNREFUSED.
• xce_retry_config_t — MISSING (Req 7).
• redirect_host / redirect_port fields in XCE_ERR_STANDBY error reply — MISSING (Req 7).

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2. Requirement-to-Asset Map

Req	Key Gap	Key Reusable Asset	Gap Tag
1 — Listener before election	CTRL_INIT/CTRL_ELECTING enum values; pre-dispatch gate in vtaskmgr; extract bind+listen from phase2; ha_wait_for_heartbeat_or_timeout(); heartbeat_seen semaphore	iomgr epoll, vtaskmgr dispatch switch, xorshift64 jitter	Missing
2 — Quorum election	Entire am_i_primary_quorum() and vote protocol; ha_vote_entry_t, ha_elect_ctx_t; handle_request_vote() / _reply(); ha_elect_evaluate_and_signal(); OP_requestVote capnp schema	ha_do_promote/demote, jitter PRNG, applied_lsn, iomgr async connect	Missing
3 — Config bootstrap	bootstrap_config_if_needed(); xce_probe_config_tag(); OP_probeConfigTag capnp; defer_config_fetch flag in ha_state_t	do_one_config_fetch() (wired), connect_ssl_raw()	Missing
4 — Startup validation	--vcpus N CLI arg; even-N peer count check; cert pre-flight access(); SSL_CTX_free ASAN fix	argp option parsing pattern in main.c	Missing
5 — Majority-commit WAL	repl_broadcast() implementation; repl_wait_majority_ack(); committed_lsn in persist_t; persist_truncate_wal_above(); committed_lsn in heartbeat; last_known_committed_lsn in ha_state_t	repl_wait_ack() logic, standby_conn_t, repl_start/complete_catchup, WAL sync path	Missing / Stub
6 — Persistent channel	Persistent TCP fd per standby; ha_find_and_connect_to_primary(); EPOLLRDHUP failover; extended OP_ctrlHello; OP_snapshotTransfer; OP_walCatchupEntry; WAL streaming loop; heartbeat vtask; three-tier discovery	iomgr EPOLLIN/EPOLLRDHUP, repl_needs_snapshot(), repl_start/complete_catchup()	Missing
7 — Client retry	Retry loop in libxce; xce_retry_config_t; redirect fields in error reply	ha_should_redirect(), ha_no_primary_known()	Missing
8 — Majority-commit config	repl_wait_majority_ack() (shared with Req 5); OP_upgradeConfigAck; committed_config_tag; heartbeat piggybacking	push_config_to_standbys() (fire-and-forget → upgrade)	Missing
9 — State durability	ha_persist_term(); ha-term.bin read in ha_init(); voted_for_term/voted_for_name in ha_state_t	Atomic write+rename pattern (existing in config_repl.c)	Missing
10 — Observability	Structured log statements throughout all new code paths	Existing INFO/WARN/ERROR macros (xcelog.h)	Missing (alongside)

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3. Implementation Approach Options

Option A: Change-at-a-time (recommended)

Implement changes in dependency order: D → A → B → C → E → H → F → G → (observability woven in).

Rationale for ordering:

1. D first: --vcpus N removes vtaskmgr's config dependency, unblocking A.
2. A before B: listener must be open before election dispatch works.
3. B before C: config bootstrap needs the proven election winner from quorum election.
4. E and H together: both use repl_broadcast() + repl_wait_majority_ack(); implement infrastructure once.
5. F after E: persistent channel carries WAL entries; broadcast must send over that channel.
6. G last: retry makes sense only after the controller states it retries against are implemented.

Files touched per change:

• D: main.c, cluster.c (remove vcpus from config), ha.c (SSL_CTX_free)
• A: ha.h (enum + semaphore + fields), myapp.c (startup reorder), cluster.c (extract listener), ha.c (wait function, dispatch gate)
• B: ha.h (new types), ha.c (replace am_i_primary), capnp schema, cluster.c (dispatch handler)
• C: config_repl.c (bootstrap_config_if_needed, xce_probe_config_tag), capnp schema, myapp.c (integration)
• E: repl.c (repl_broadcast, repl_wait_majority_ack), persist.h/persist.c (committed_lsn, persist_truncate_wal_above), ha.h/ha.c (last_known_committed_lsn)
• H: config_repl.c (upgrade majority-commit), capnp schema, ha.h (committed_config_tag)
• F: ha.c/cluster.c (channel connect, extended hello, streaming, EPOLLRDHUP)
• G: src/lib/ (retry loop, xce_retry_config_t, redirect fields)

Trade-offs:

• ✅ Each atomic commit is testable before the next starts
• ✅ Follows existing TDD convention (failing test first)
• ❌ Long sequential dependency chain; F and G can only start late

Option B: Infrastructure-first parallel tracks

Track 1 (election+bootstrap): D → A → B → C
Track 2 (replication): E → H
Join (channel): F using Track 1 + Track 2 artifacts
Final: G

Trade-offs:

• ✅ Track 1 and Track 2 are mostly independent until F
• ❌ Track 2 cannot be fully validated without Track 1 (no quorum without election)
• ❌ More coordination overhead between developers on shared ha.h

Option C: Stub-forward then wire

Add all new stubs with -ENOSYS first, then wire each one. Matches the existing codebase pattern (many stubs already present).

Trade-offs:

• ✅ Compiles throughout; no long broken-build windows
• ❌ Stub-first delays real testability; TDD mandate disfavors this

Recommendation: Option A. The dependency chain is well-defined and single-developer serial implementation is the realistic mode for this C codebase.

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4. Effort and Risk Summary

Req	Effort	Risk	Justification
1 — Listener before election	M (3–5d)	Medium	Refactor startup order; must remove vtaskmgr/config dependency first
2 — Quorum election	XL (2+ wks)	High	Full algorithm replacement; new wire protocol; FSM extension; concurrent dispatch
3 — Config bootstrap	M (3–5d)	Medium	New function + probe RPC; depends on do_one_config_fetch (wired)
4 — Startup validation	S (1d)	Low	Additive CLI + validation; ASAN one-liner
5 — Majority-commit WAL	L (1–2 wks)	High	committed_lsn cross-cuts persist+repl+ha; repl_broadcast must become real
6 — Persistent channel	XL (2+ wks)	High	New connection lifecycle; full state sync protocol; 3-tier discovery
7 — Client retry	M (3d)	Low	Well-understood retry pattern; additive libxce change
8 — Majority-commit config	M (3d)	Medium	Shares Req 5 infrastructure; mainly wiring push_config_to_standbys
9 — State durability	S (1d)	Low	File write+read; extends ha_init
10 — Observability	S (alongside)	Low	Log statements woven into each change

Total estimated effort: 6–9 weeks for one engineer implementing with full TDD.

High-risk dependencies:

• Req 2 must complete before Req 3 can be integrated end-to-end.
• Req 5 (repl_broadcast implementation) must complete before Req 8 and before Req 6 (WAL streaming over the channel).
• Req 4 (vcpus CLI) must complete before Req 1 (vtaskmgr before election).

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5. Key Reusable Assets

Asset	Location	Reuse in
repl_add/remove_standby	repl.c	Req 6 (channel registration)
repl_start/complete_catchup	repl.c	Req 6 (state sync protocol)
repl_needs_snapshot	repl.c	Req 6 (snapshot decision)
repl_on_ack	repl.c	Req 5 (majority-commit ack handler)
repl_trim_lsn	repl.c	Req 5 (WAL trim with committed_lsn)
connect_ssl_raw()	netio.c/config_repl.c	Req 3 (probe RPC)
do_one_config_fetch()	config_repl.c	Req 3 (deferred fetch)
xorshift64_next + ha_seed_jitter	ha.h / ha.c	Req 1, 2 (jitter)
ha_do_promote / ha_do_demote	ha.c	Req 2, 6 (role transitions)
ha_should_redirect / ha_no_primary_known	ha.c	Req 7 (retry redirect)
iomgr epoll + EPOLLIN/EPOLLRDHUP	iomgr (cluster.c)	Req 1, 6
Atomic write+rename pattern	config_repl.c	Req 9 (ha-term.bin)
INFO/WARN/ERROR macros	xcelog.h	Req 10

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6. Constraints for Design Phase

• C gnu17, no C++, no new external dependencies.
• ASAN build (nix build .#xcecore_debug) must pass after every change.
• Static peer membership: --peers list is fixed at startup; no dynamic join/leave of controller peers. Quorum denominator is fixed for cluster lifetime.
• TDD mandatory: failing test in src/controller/testsuite/ before each implementation change.
• make test must pass without a live server at every commit.
• commit_timeout_ms must be configurable (default 5000ms).
• Single-node mode (no --peers): quorum=1 everywhere; all new majority-commit paths must short-circuit to self-only.
• WAL write stall window (operational constraint, not a bug): during standby catch-up after election, repl_wait_majority_ack() will time out on every write until at least one standby completes catch-up. This is correct CP behavior; operators must be warned in docs.

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7. Research Needed (Design Phase)

• vtaskmgr API for pre-election dispatch: confirm that vtaskmgr_init(vcpus) can be called before cluster_config is loaded (after removing vcpus from config struct). Verify no hidden config dependency.
• iomgr async connect pattern for vote requests: confirm iomgr_async_vote_request() can be implemented using existing async connect infrastructure without new socket primitives.
• capnp schema extension: confirm the capnp code-generation toolchain can add OP_requestVote, OP_probeConfigTag, OP_walAck, OP_upgradeConfigAck, OP_snapshotTransfer, OP_walCatchupEntry without breaking existing decode paths.
• persist_truncate_wal_above() safety: verify WAL segment file structure supports efficient truncation at arbitrary LSN boundary without full segment rewrite.
• libxce client API surface: identify the exact function in src/lib/ that wraps xce_encode()+send+recv+xce_decode() to locate the correct insertion point for retry logic.

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Gap Analysis (Updated — Brownfield Audit)

Analysis date: 2026-06-01. Branch: persistent_ha. Phase: tasks-generated. This section audits current implementation state vs. all 11 task groups.

Analysis Summary

• Scope: 10 requirements across 11 task groups. 30 subtasks checked [x]; only section headers and integration tasks 11.1–11.5 remain [ ].
• Implementation status: ~95% complete. All core subtasks (1.1–10.2) are marked done and confirmed implemented: CTRL_INIT/CTRL_ELECTING enum, ha-term.bin durability, repl_wait_majority_ack, persist_truncate_wal_above, xce_request_with_retry, xce_probe_config_tag, repl_broadcast (real, not stub).
• Key architectural shift since original research: The election-iomgr-refactor spec superseded parts of this spec. bootstrap_config_if_needed and ha_find_and_connect_to_primary are no longer called from myapp_run — standby connection is inbound (primary dials standby via on_standby_connected). ha_find_and_connect_to_primary exists only as a test hook reference in ha.h.
• Remaining work: Tasks 11.1–11.5 are manual/integration tests documented in manual-tests.md. The build passes with all unit tests green.
• Effort remaining: S (1–2 days for manual integration test execution + result recording). Risk: Low.

Requirement-to-Asset Map (Current State)

Req	Status	Key Evidence
1 — Listener before election	✅ Done	CTRL_INIT=2, CTRL_ELECTING=3 in ha.h; cluster_open_listener() called before election in myapp.c; ha_wait_for_heartbeat_or_timeout() implemented
2 — Quorum election	✅ Done	am_i_primary_quorum → superseded by ha_start_election_async + raft library (election-iomgr-refactor); handle_request_vote, ha_elect_evaluate_and_signal implemented
3 — Config bootstrap	✅ Done (changed arch)	xce_probe_config_tag() implemented in config_repl.c:1140; bootstrap_config_if_needed removed from myapp_run per election-iomgr-refactor task 5.3; defer_config_fetch field exists in ha_state_t; post-election config push via ha_send_ctrlhello_to_all_standbys covers deferred fetch
4 — Startup validation	✅ Done	startup_validation.c exists; cert pre-flight, peer count validation, vcpus CLI implemented; SSL_CTX_free ASAN fix in ha_fini
5 — Majority-commit WAL	✅ Done	repl_broadcast() real implementation (repl.c:193+); repl_wait_majority_ack() implemented (repl.c:338+); committed_lsn in persist_t (persist.c:1029); persist_truncate_wal_above() implemented (persist.c:1293+)
6 — Persistent control channel	✅ Done (changed arch)	primary_ctrl_fd in ha_state_t; ha_on_primary_ctrl_fd_rdhup triggers re-election; inbound channel via on_standby_connected in ha.c; ha_arm_heartbeat_timeout_vtask for timeout detection; ha_find_and_connect_to_primary is a hook-only reference now (CTRL_STANDBY never dials out)
7 — Client retry	✅ Done	xce_request_with_retry() + xce_retry_config_t in request.c/request.h (request.c:1664+)
8 — Majority-commit config	✅ Done	OP_upgradeConfigAck handler; committed_config_tag in ha_state_t; push_config_to_standbys upgraded; repl_wait_majority_ack with OP_upgradeConfigAck discriminant
9 — State durability	✅ Done	ha_persist_term() / ha_restore_term() in ha.h:317-340; ha-term.bin read in cluster_init_phase1 (cluster.c:809); voted_for_name field in ha_state_t
10 — Observability	✅ Done	Structured INFO/WARN log statements throughout all paths

Gaps: Tasks 11.1–11.5 (Manual Integration Tests)

Gap 1: Task 11.1 — Concurrent startup and config-fresh election

• What's needed: 3-node cluster starts simultaneously; verify only one elects primary; config-fresh node wins.
• How to run: See manual-tests.md — Test 1 (3-node clean start, verify ctrl-a primary).
• Infrastructure: deploy-ha.sh + start.sh scripts; log grep for CTRL_PRIMARY.
• Effort: ~30 min.

Gap 2: Task 11.2 — Failover and WAL durability

• What's needed: Kill primary; verify standby detects via heartbeat timeout → promotes; committed WAL survives.
• How to run: manual-tests.md Test 2.
• Effort: ~30 min.

Gap 3: Task 11.3 — Unconfigured node bootstrap

• What's needed: Start node with config_tag=0; verify it receives config via primary's ctrlhello push after election.
• How to run: manual-tests.md Test 3.
• Note: Architecture changed — the deferred fetch now happens via ha_send_ctrlhello_to_all_standbys (primary pushes), not do_one_config_fetch (standby pulls). This is simpler and already works by default.
• Effort: ~30 min.

Gap 4: Task 11.4 — Config upgrade majority-commit and term durability

• What's needed: Config upgrade, partition, timeout; restart with persisted term.
• How to run: manual-tests.md Test 4.
• Effort: ~30 min.

Gap 5: Task 11.5 — Full ASAN build verification

• What's needed: nix build .#xcecore_debug clean.
• Status: Unit tests pass under /xce-build controller (which uses debug+ASAN). Full nix build is the final check.
• Effort: ~15 min build time.

Constraints Carried Forward

• ha_find_and_connect_to_primary is dead code: Declared in ha.h with test hook but never called in production. CTRL_STANDBY waits for primary to dial in. Safe to delete in cleanup pass.
• bootstrap_config_if_needed removed from myapp_run: Covered by primary-push model in election-iomgr-refactor. Tasks 5.2–5.3 [x] reflect the original design; the implementation pivoted to push-on-ctrlhello.
• Single-node path: Verified via test_ha_election.c single-node shortcircuit.

Implementation Approach Recommendation

No new code needed. Proceed directly to manual integration test execution:

1. Run /xce-build to confirm full build clean.
2. Execute manual-tests.md tests 1–5 in order.
3. Record results in the Results Template at the bottom of manual-tests.md.
4. Mark tasks 11.1–11.5 [x] on pass.
5. Run nix build .#xcecore_debug for 11.5 ASAN verification.