Native Windows CI (Python 3.12/3.13) rejected untouched files with
CaptureChanged because the path stat and the descriptor fstat disagree
there (change time versus creation time, possibly dev/ino encodings).
The descriptor is now checked against the path only on the API-stable
facts (size, mtime_ns); the full identity (size, mtime_ns, ctime_ns,
dev/ino where meaningful) is compared between the fstat before and
after the copy and between the path stats before and after. A test
injects shifted fstat results to simulate the Windows discrepancy, and
a fresh file is captured twice with no platform guard.
Error messages carry strerror only, never the path (the path goes to
the debug log); a test asserts no CaptureError names the root. Files
are unlinked outside the store lock; close() during an in-flight
capture lets that worker remove its temp file and then the directory.
get() documents that readers of capture.path must acquire/release_use.
The test fixture resolves its temp root (macOS /private/var, Windows
8.3 names). TESTING.md states the real identity contract.
Python 3.12+ on Windows reports the change time from stat but the
creation time from fstat, so a freshly written file whose creation and
write straddle a clock tick failed the pre-read identity check with
CaptureChanged. The path-versus-descriptor checks now compare size,
mtime_ns and dev/ino; ctime_ns is compared between the fstat before
and after the copy, where it still detects a same-size rewrite with a
restored mtime on POSIX.
The symlinked-root test asserted the locator against the unresolved
temp path, which macOS (/var -> /private/var) and Windows (short names)
resolve differently; it now compares against the real path.
Add utils/media_capture.py: CaptureStore copies one rooted media file
into an owner-only prompt-manager-captures-* temp directory, streaming
it in 1 MiB chunks while computing the whole-file SHA-256, and compares
the opened descriptor with the path (dev, ino where meaningful, size,
mtime_ns, ctime_ns) before and after the copy; any disagreement raises
CaptureChanged and removes the copy. Symlinked files or directories,
root escapes, non-media names and directories raise CaptureDenied; the
locator is normcase(join(realpath(root), relative)), the listing's
identity, so a symlinked root matches it.
Limits are the plan's: 256 MiB per file on stat and stream
(CaptureTooLarge), 8 completed captures, 512 MiB reserved and 2
capture/verify workers with nonblocking admission (CaptureCapacity),
900 s idle and 1800 s hard lifetimes on an injected clock. acquire and
release_use keep an in-use capture past expiry, release and
invalidate_all until its last use ends; close removes only owned files
and the owned directory. A header-only probe of the copy marks Generate
unsupported above 4096 px per side or 16,777,216 px, for unreadable
headers and for video; verify re-hashes the current file without a
copy. Every handle closes before unlink.
tests/test_media_capture.py covers exact bytes and owner-only modes,
alias and escape denial, the symlinked-root locator, change detection
during the copy (size, same-size rewrite with restored mtime through
the POSIX change time, inode replacement), both size caps, count, byte
and worker admission, idle and hard expiry with in-use retention,
cleanup scope, handle release at unlink, dimension and video
readiness, and the allowlist equality with the inspection service.
TESTING.md documents the store and the Windows change-time limit.
Vito Sansevero