# Phase C+23 — Cold-vs-cold verification

**Date:** 2026-05-26
**Mode:** Engine modified (`vd_query_video_flags` constant return).
Cold-vs-cold protocol: fresh `xrs-c23` cold runs vs archived canary
jitter set.

## Methodology

- ours-cold jsonls: `/tmp/ours-c23-vd-cold-{1,2,3}.jsonl` (28.7 MB
  each, 108,507 events on tid=1). Captured under
  `XENIA_CACHE_WIPE=1` with the freshly built `xrs-c23` binary
  (release, post-fix).
- canary jitter set: 3 archived cold runs `canary-jitter-{1,2,3}.jsonl`
  (4.4 / 3.5 / 3.7 GB) from
  `xenia-canary/build-cross/bin/Windows/Debug/`. Same reference
  jitter set used in C+20, C+21, C+22, Phase D Stage 0..4.
- tid map: `--tid-map 6=1` (canary main thread → ours main thread).

## Pre-C+23 baseline (post-C+22)

```
matched=105,138 across all 3 jitters
first divergence: kernel.return VdQueryVideoFlags
                  canary=3 ours=0
                  at idx 105,138 (tid=6→1)
```

## Post-C+23 (3-jitter table)

| jitter | matched | first divergence at | first-divergence kind / payload |
|---|---|---|---|
| 1 | **105,286** | 105,286 | `import.call VdGetCurrentDisplayGamma` (canary) vs `import.call KeAcquireSpinLockAtRaisedIrql` (ours) |
| 2 | **105,286** | 105,286 | (same) |
| 3 | **105,286** | 105,286 | (same) |

Delta vs baseline: **+148 events** in main matched-prefix on all
three jitters. The new first divergence (`VdGetCurrentDisplayGamma`
vs `KeAcquireSpinLockAtRaisedIrql`) is genuine and identical across
all three jitters.

## Absorber counters (sanity)

| jitter | floating_create (c/o) | floating_wait (c/o) |
|---|---|---|
| 1 | 0 / 0 | 1 / 0 |
| 2 | 0 / 0 | 0 / 0 |
| 3 | 1 / 0 | 3 / 0 |

Within the expected scheduling-jitter window. Matched-prefix
stable at 105,286 across all three.

## Sister chains

No sister chain regressions: the diff report lists only the main
`tid=6 → tid=1` chain (no sister chains exercised in the new
window). All previously matched sister chains
(11, 32, 4, 41, 16) remain unaffected because they fire outside
the 105,138–105,286 window.

## Determinism (3 cold runs)

| run | md5 | matched-prefix vs jitter-1 | ours_total |
|---|---|---|---|
| cold-1 | `4e2e781ff0609f3a0a08f573dee4be4e` | 105,286 | 108,507 |
| cold-2 | `b195d82a1b61e87d6f54a2ac2b3e091b` | 105,286 | 108,507 |
| cold-3 | `e6b94d4dc151007c924b81bbc5c9faf5` | 105,286 | 108,507 |

The byte-level md5 differs (host_ns/guest_cycle wall-time jitter,
expected) but the logical semantic state — matched-prefix,
ours_total, first-divergence index, divergent payloads — is
bit-identical across all 3 runs.

New cold baseline digest (representative cold-1):
**`4e2e781ff0609f3a0a08f573dee4be4e`**.

## Phase B `image_canonical_sha256`

Pinned hash `ea8d160e…` UNCHANGED. No XEX loader changes; only
kernel export logic modified.

## Test suite

xenia-kernel: **226 PASS** (was 224 + 2 new).

## Conclusion

Phase C+23 advances main matched-prefix from 105,138 → 105,286
across all three canary jitter cold runs (+148 events,
+0.0311% of canary total). The next divergence is a real
post-VdSwap control-flow mismatch unrelated to video flags.

Engine MODIFIED (~50 LOC: 1 registration edit + 6 LOC function
body + 40 LOC tests). Diff tool UNCHANGED. Phase B
`image_loaded_sha256` ε class boundary UNCHANGED.

Tripstones 1, 2, 3, 4, 5, 6 honored.