# Phase C+23 re-validation (2026-05-18)

## Protocol followed

Cold-vs-cold per reading-error #31 + #32 + #33 + #34.

1. ✓ Backed up both canary cache locations
   (`xenia-canary/build-cross/bin/Windows/Debug/cache/` and
   `~/.local/share/Xenia/cache/`) to tarballs in
   `xenia-rs/audit-runs/phase-c23-keWait-timeout-encoding/`.
2. ✓ Wiped both canary caches + ours's
   (`~/.local/share/xenia-rs/cache/` + `/tmp/xrs-cache-c23-*`).
3. ✓ Cold-ran ours (50M instructions) against the `.iso`
   path — NOT the loose `default.xex` (per #34).
4. ✓ Cold-ran canary with phase_a_event_log_path set, killed after
   ~95s timeout, with `--mute=true`.
5. ✓ Truncated canary log to first 250k events for tid=6 / 20k for
   sisters (using existing C+19 truncate.py).
6. ✓ Ran `diff_events.py` with full tid map
   `6=1,7=2,4=11,12=7,14=9,15=10`.
7. ✓ Restored both canary cache backups.
8. ✓ Reverted canary config (`phase_a_event_log_path` back to `""`).

## Determinism check

3 cold ours runs against `.iso`, det-fields-only MD5:

| run | digest                              |
|-----|-------------------------------------|
| 1   | 23cf4c4cbf61a577caa4118ab2308ba6    |
| 2   | 23cf4c4cbf61a577caa4118ab2308ba6    |
| 3   | 23cf4c4cbf61a577caa4118ab2308ba6    |

PASS — bit-stable. Replaces C+22's `e1dfcb1559f987b35012a7f2dc6d93f5`
baseline (digest moved due to addis behavioral change).

## Phase B image hash

`image_canonical_sha256 = ea8d160e9369328a5b922258a92113efb8d7
ce3e1a5c12cc521e375985c91c18` — UNCHANGED. The image-loading path
is unaffected.

## Gate matrix

| gate                                        | result                         |
|---------------------------------------------|--------------------------------|
| Engine source change minimal                | PASS (~25 LOC, 1 file)         |
| CPU tests (xenia-cpu) — pre vs post         | 288 → 291 (3 new, 0 regressions) |
| Kernel tests (xenia-kernel)                 | 204 unchanged (no regressions) |
| Diff-tool source unchanged                  | PASS                           |
| Phase A schema version 1 unchanged          | PASS                           |
| ours-cold byte-stable across 3 runs         | PASS (digest unchanged)        |
| Main matched-prefix preserved at C+22       | PASS (104,607)                 |
| Sister tid=12→7 advanced                    | PASS (3 → 4)                   |
| Sister tid=4→11 / 7→2 / 14→9 / 15→10        | PASS (all preserved)           |
| Phase B image hash preserved                | PASS (ea8d160e…)               |
| Canary caches restored                      | PASS                           |
| Canary config restored                      | PASS                           |
| Workspace build clean                       | PASS                           |
| `--mute=true` used                          | PASS                           |
| Renamed binary used (xrs-c23)               | PASS                           |
| Cold-vs-cold against `.iso`                 | PASS (per #34)                 |

## What changed in the diff-tool report compared to C+22 baseline

| metric                       | C+22    | C+23    | delta |
|------------------------------|---------|---------|-------|
| matched tid=6→1              | 104,607 | 104,607 | 0     |
| matched tid=4→11             | 11      | 11      | 0     |
| matched tid=7→2              | 32      | 32      | 0     |
| matched tid=12→7             | 3       | **4**   | **+1** |
| matched tid=14→9             | 41      | 41      | 0     |
| matched tid=15→10            | 16      | 16      | 0     |
| ours-cold total events       | 121,569 | 121,569 | 0     |
| ours-cold det-fields digest  | e1dfcb15… | 23cf4c4c… | NEW |
| Phase B image hash           | ea8d160e… | ea8d160e… | 0   |

## Outcome

- C+23 = LANDED. tid=12→7 chain advances +1 (3 → 4).
- 5 LOC effective engine change (CPU interpreter `addis`).
- 3 new regression tests in xenia-cpu (lib tests 288 → 291).
- Determinism preserved. Phase B image hash preserved.
- All other sister chains and main preserved.
- New downstream divergence at idx=4 is C+22-class scheduler
  determinism (out of scope for this phase).