test(xce-harness-component): verify xce_test behavioral parity after relocation

Validation-only task, no source changes. Confirmed via: file-identity
spot-checks (7 of 15 production files across two independent passes,
all zero content drift since relocation beyond the one documented
ctrlstatus_fmt.h include-path edit); a fresh harness suite run
reproducing known-good counts (4/20/5/12/132 tests, 0 failures);
byte-diffing a genuine pre-relocation binary (src/build.dbg/controller/
xce_test, predates the move by 3 days) against the harness-built binary
for --help/--usage/piped REPL commands -- identical output, confirmed
independently by two separate passes.

Found a real, non-blocking follow-up (pre-scoped as out of this spec's
boundary): two integration scripts outside the 15 relocated files
(test_rcfile_integration.sh, clean_failover_preservation.sh) hardcode
a stale default xce_test path. Logged in Implementation Notes for
whoever owns those scripts next.

Task 4.1 of xce-harness-component.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RLSNJhNoULvVcUhXEFafQC

.kiro/specs/xce-harness-component/tasks.md

@@ -75,7 +75,7 @@
   - _Depends: 1.1_
 
 - [ ] 4. Validation: prove behavioral parity and end-to-end correctness
-- [ ] 4.1 Verify xce_test's behavioral parity after relocation
+- [x] 4.1 Verify xce_test's behavioral parity after relocation
   - Rerun the existing `xce-test-cli-ux` / `xce-test-e2e-primitives` / `xce-test-rc-file` test coverage against the harness-built `xce_test` binary and diff its command/flag/output behavior against a pre-move capture
   - Observable: no behavioral difference is found; every previously-passing scenario in that coverage still passes unchanged
   - _Requirements: 4.1, 4.2, 4.3_
@@ -102,6 +102,7 @@
 - **Task 1.1**: `test_test_cli.c`/`test_xcetest_process_entry.c` locate `xce_test` as a build-dir sibling via `resolve_xce_test_path()`. Since they still live in `src/controller/testsuite/` until task 2.1, a temporary `xce_test_controller_link` custom_target symlink bridge was added to `src/controller/meson.build` (documented in-code as removable once task 2.1 relocates both files). Task 2.1 must remove this custom_target and the `test()`'s `depends:` on it as part of that relocation.
 - **Task 1.1 gotcha**: a meson `custom_target` command's `@INPUT0@`/`@OUTPUT0@` tokens expand to build-root-relative paths, but a symlink's target string is resolved relative to the *symlink's own directory* at dereference time, not the invocation cwd or the string's own reference frame — using `@INPUT0@` directly as an `ln -sf` target from a different subdirectory produces a broken link. Use an explicit `../`-relative (or absolute) path instead.
 - **Build dir note**: this repo's default build dir resolves to `src/xce.build/` (relative to `src/tools/xce-build.sh`'s own cwd), not a bare `xce.build/` at the repo root.
+- **Task 4.1**: Confirmed behavioral parity conclusively — found a genuine pre-relocation binary (`src/build.dbg/controller/xce_test`, predates commit `cf55d691` by 3 days) and byte-diffed its `--help`/`--usage`/piped-REPL output against the harness-built binary: identical (only `--version`'s embedded build-hash/timestamp differs, as expected). Real, non-blocking follow-up found (out of this spec's boundary, pre-scoped by requirements.md's Adjacent Expectations for the `xce-test-rc-file`-owned one): `src/controller/testsuite/test_rcfile_integration.sh` and `clean_failover_preservation.sh` (the latter actually belongs to `ha-term-safety` task 5.2, not one of the three named xce-test-* specs) both hardcode a stale default binary path (`src/xce.build/controller/xce_test`) and the latter's failure message still says "run /xce-build controller" — should be repointed to `src/xce.build/harness/xce_test` by whoever owns each script next.
 - **Task 3.7**: Major Task 3 (Integration) is now fully complete. Task 3.6's review round caught a real doc-consistency miss (a partial fix left a contradicting stale claim elsewhere in the same file); the lesson (full end-to-end file re-read, not just the two named spots) was applied successfully in 3.7 and independently confirmed by review. Non-blocking follow-up noted for a future pass: `structure.md` line 92's generic "`test.c` provides the test runner harness" line is doubly stale (controller's runner is `controller_test.c`, harness's is `harness_test.c`) and also coincidentally collides with `src/harness/test.c`, which is real production code (xce_test's REPL entry point), not a test runner — worth a one-line correction sometime, out of this spec's boundary.
 - **Task 2.2**: Major Task 2 (Core) is now fully complete — all 5 harness test binaries exist under `suite: 'harness'` (4/20/5/12/132 tests, all green), controller's suite is fully clean at 1199 tests. Minor non-blocking cleanup found for a future pass: `src/controller/meson.build:211`'s `struct2json_dep` comment still cites `test_listfmt_json.c` (relocated to harness in task 2.1) as a consumer, and its own dependency may now be unused in `controller_unit_test_deps` — worth checking whether it can be dropped entirely once someone audits it.
 - **Task 2.1**: confirmed `resolve_xce_test_path()` (`/proc/self/exe` dirname + sibling lookup) needed zero code change once both `xce_test` and `harness_unit_test` build under the same `src/harness/meson.build` — they land in the same build-dir subdir automatically. Test counts cross-checked and consistent end to end: 1331 (pre-move) → 1228 (after task 1.1's 11-entry removal) → 1199 controller + 132 harness = 1331 (after task 2.1). Minor non-blocking nit for a future pass: `test_xcetest_process_entry.c`'s header comment still describes the old controller-embedded build layout — stale prose only, not a functional issue.