handoff: VSync/event-wedge fixes + iterate 2.A–2.BC research notes

Source changes (dormant parity infra, retained from iterate 2.AI/2.AO):
- xenia-kernel/exports.rs: nt_create_event manual_reset polarity +
  related event wiring
- xenia-gpu/mmio_region.rs: D1MODE_VBLANK_VLINE_STATUS hardcode parity

Also lands the audit-runs/ analysis notes (.md/.txt/.json digests) for the
iterate 2.x VSync/0x10e8/0x1004 wedge investigation. Raw trace dumps
(.jsonl/.gz/.csv/.stdout) and agent worktrees (.claude/) are gitignored as
regenerable local artifacts — see memory + HANDOFF for the running findings.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

audit-runs/phase-c9-XamContentCreateEnumerator/re-validation.md

@@ -0,0 +1,77 @@
+# Phase C+9 — XamContentCreateEnumerator re-validation
+
+## Gate matrix
+
+| # | gate | result |
+|---|---|---|
+| 1 | cvar-OFF determinism 50M (3 runs) | PASS — all 3 = `b8fa0e0460359a4f660adb7605e053de` (new baseline; coarse fields shifted: imports 40470→40465, ±5 reflecting downstream branch flip from the 0x525 return) |
+| 2 | Phase B `image_loaded_sha256` | PASS — `ea8d160e9369328a5b922258a92113efb8d7ce3e1a5c12cc521e375985c91c18` (matches baseline; XEX loader untouched) |
+| 3 | Phase A main chain matched-prefix > 102197 | PASS — **102404** (+207 from 102197) |
+| 3b | tid=4 → 11 unchanged | PASS — 9 (no regression) |
+| 3c | tid=7 → 2 unchanged | PASS — 29 (no regression) |
+| 3d | tid=12 → 7 unchanged | PASS — 2 (no regression) |
+| 3e | tid=14 → 9 unchanged | PASS — 39 (no regression) |
+| 3f | tid=15 → 10 unchanged | PASS — 15 (no regression) |
+| 4 | Build clean | PASS (1 unrelated `walk_committed_regions` dead-code warning, pre-existing) |
+| 5 | Phase A emitter determinism (2 runs) | PASS — both det-fields md5 = `0b299c37b8fe9fd4ee1b1877a875543f` |
+| 6 | Unit tests | PASS — 160 → **165** (+5 new, 0 regressions) |
+
+## Stable-digest comparison
+
+| field | C+8 baseline | C+9 post-fix | delta |
+|---|---|---|---|
+| instructions | 50000000 | 50000002 | +2 (engine ticks; jittery) |
+| imports | 40470 | 40465 | -5 (game took the 0x525 branch, calls fewer of something) |
+| unimpl | 0 | 0 | 0 |
+| draws | 0 | 0 | 0 |
+| swaps | 1 | 1 | 0 |
+| unique_render_targets | 0 | 0 | 0 |
+| shader_blobs_live | 0 | 0 | 0 |
+| texture_cache_entries | 0 | 0 | 0 |
+
+C+8 baseline `c6d895829b4611964978990ae1cb8a6a` → C+9 baseline
+`b8fa0e0460359a4f660adb7605e053de`. First non-trivial digest movement
+in 4 Phase C sub-sessions — the `0x525` return flips at least one
+downstream branch decision, producing 5 fewer import calls within 50M
+instructions.
+
+## Phase A determinism
+
+ours.jsonl       (run 1) det-fields md5: `0b299c37b8fe9fd4ee1b1877a875543f`
+ours-determ.jsonl (run 2)              : `0b299c37b8fe9fd4ee1b1877a875543f`
+
+Byte-identical on deterministic fields. New `--phase-a` det baseline
+(`0b299c37…`), replacing C+8's `9135e369…`. Reflects the downstream
+trajectory shift caused by the return-value flip at idx=102197.
+
+## Per-chain summary
+
+| chain | C+8 KeResetEvent | C+9 XamContentCreateEnumerator | delta |
+|---|---|---|---|
+| canary tid=6 → ours tid=1 (main) | 102197 | **102404** | **+207** |
+| canary tid=4 → ours tid=11 | 9 | 9 | 0 (sister at end of ours window) |
+| canary tid=7 → ours tid=2 | 29 | 29 | 0 (sister at end of ours window) |
+| canary tid=12 → ours tid=7 | 2 | 2 | 0 (different bug: KeWaitForSingleObject 258 vs 0) |
+| canary tid=14 → ours tid=9 | 39 | 39 | 0 (different bug: XAudio vs RtlEnterCS) |
+| canary tid=15 → ours tid=10 | 15 | 15 | 0 |
+
+All gates pass. No regressions.
+
+## Next target
+
+`canary tid=6 → ours tid=1` main, idx **102404**:
+`NtQueryFullAttributesFile`
+- canary return_value=0 (`STATUS_SUCCESS`) — file/path exists
+- ours   return_value=3221225524 (`0xC0000034 STATUS_OBJECT_NAME_NOT_FOUND`) — file/path missing
+
+Likely a VFS/cache path-existence divergence: canary has a pre-populated
+content directory or HDD-backing mount that responds SUCCESS to a
+specific Sylpheed query path, while ours's fresh-boot VFS rejects it.
+Sister of AUDIT-053/054 (VFS layout aliasing) and the AUDIT-052 cache
+persistence question.
+
+The args/path string is not captured in the Phase A event payload
+(emitter gap — kernel.call args resolution for `lpstring_t` not wired).
+First step in Phase C+10 will be capturing the path (either via the
+existing emitter or a one-shot --trace-imports run with the same
+ISO + binary).