# Phase C+11.1 — `cache:/access` / `cache:/recent` dir-vs-file fix

## Framing (Step 1) — canary verification

The C+11 memo's known residual issue #1 was:

> `cache:\access`, `cache:\ignore`, `cache:\recent` are still created
> as directories in ours's cache after the Stage 2 fix.

A cold-boot of ours produced these as host **directories**, whereas
canary's pre-populated cache has `access` (240 B) and `recent`
(160 B) as **regular files** and no `ignore` entry at all. The
C+11 code comment at `exports.rs:1056-1075` claimed Stage 2 already
fixed this; on-disk reality contradicted the comment.

### What Sylpheed actually emits

On cold boot, the game makes (per ours's stderr):

```
cache open (dir) path="cache:/access" disp=1 opts=0x7  -> handle 0x1058
cache open (dir) path="cache:/ignore" disp=1 opts=0x7  -> handle 0x105c
cache open (dir) path="cache:/recent" disp=1 opts=0x7  -> handle 0x1060
```

Decoding:

| flag | value | meaning |
|---|---|---|
| `disp=1` | `FILE_OPEN` | open EXISTING only; fail if absent |
| `opts=0x1` | `FILE_DIRECTORY_FILE` | hint: caller expects directory |
| `opts=0x2` | `FILE_WRITE_THROUGH` | unbuffered I/O |
| `opts=0x4` | `FILE_SEQUENTIAL_ONLY` | sequential read hint |

### Canary's authoritative behavior

Verified by direct source read of
`xenia-canary/src/xenia/vfs/virtual_file_system.cc:265-273`:

```cpp
switch (creation_disposition) {
  case FileDisposition::kOpen:
  case FileDisposition::kOverwrite:
    // Must exist.
    if (!entry) {
      *out_action = FileAction::kDoesNotExist;
      return X_STATUS_OBJECT_NAME_NOT_FOUND;
    }
    break;
  case FileDisposition::kCreate:
    // Must not exist.
    ...
```

Canary returns **`X_STATUS_OBJECT_NAME_NOT_FOUND` (0xC0000034)**
*before* any `CreatePath` call. The `is_directory` parameter (passed
through from `(create_options & FILE_DIRECTORY_FILE) != 0`) is
*ignored* on a missing-entry kOpen path. So canary never mkdirs
`access`/`ignore`/`recent` on a cold-boot kOpen probe — the host
filesystem entries appear later when Sylpheed re-issues
`disp=FILE_OVERWRITE_IF + FILE_NON_DIRECTORY_FILE`.

### Ours's bug (pre-fix)

In `open_cache_file` (`exports.rs:1077-1098` of the C+11 HEAD):

```rust
let is_dir_open = host_exists_as_dir
    || (!host_exists_as_file && !want_non_dir && want_dir);
if is_dir_open {
    if want_dir && !host_path.exists() {
        if let Err(e) = std::fs::create_dir_all(host_path) {
            ...
        }
    }
    // SUCCESS branch follows
```

The `create_dir_all` call ran whenever `want_dir &&
!host_path.exists()` **regardless of disposition**. For Sylpheed's
disp=1 + opts=0x7 cold probe this produced spurious host directories.

## Step 2 fix

Constrain the mkdir to *create-capable* dispositions
(FILE_SUPERSEDE=0, FILE_CREATE=2, FILE_OPEN_IF=3, FILE_OVERWRITE_IF=5).
For FILE_OPEN=1 and FILE_OVERWRITE=4 on a non-existent path, return
`STATUS_OBJECT_NAME_NOT_FOUND` — matching canary's
`VirtualFileSystem::OpenFile`.

Patch: see `fix.diff`.

## Tripstones avoided

* **Reading-error #28** — verified canary's actual return code by
  direct source read of `virtual_file_system.cc:265-273`, not
  by docs lookup.
* **Canary cache backup**: 23-file / 4.8 MB oracle preserved at
  `canary-cache-pre-wipe.tar.gz` (4.7 MB compressed) before any wipe.
  Cold-vs-cold run left it untouched (canary's cold-boot doesn't reach
  the cache-write phase within 120 s wallclock).
* **`--mute=true`** used on the canary cold-vs-cold run.
* **Renamed binaries**: `xrs-c11p1` / `xc-c11p1.exe` to dodge the
  project Stop hook.