[wan9chi]

Motivation

Many tools write under a temporary name and rename the result into place:

• Vitest's fsModuleCache renames each .tmp-* file to its hashed name.
• Vite's dependency optimizer renames deps_temp_* to deps.
• Astro writes .astro/*.tmp and renames them.

fspy records nothing for a rename, so those files aren't outputs. A hit doesn't restore them, and since the task reads them back, removing them is a miss.

Changes

• fspy records a rename destination as a new access kind, RenameTarget, since it may be a whole folder. A hard-link destination, always a file, is recorded as a write. Both are recorded before the call. This covers the Unix preload, the Linux seccomp supervisor and Windows NtSetInformationFile.
• A rename target that is a file counts as written. One that is a folder stands for every file under it, while the folders themselves don't count.
• A write record on a path that is a folder after the run, from opening it with write access, is ignored, so it can't pull in the files under it.
• The files under a renamed folder are archived too.
• The folder a rename came from, like Vite's deps_temp_*, is gone after the run, so a probe of it was stored as a plain NotFound input with a new random name in every entry. A path that is gone after the run but that the task wrote in now counts as written. It is still fingerprinted as missing, so validation doesn't change.

E2E cases: folder_renamed_into_place (synthetic, vtt fs rename) and vitest_fs_module_cache (Vitest 5 with fsModuleCache, true clean checkout, its today's miss line redacted with #912's redact).

Part of a stack that lets automatic tracking cache tasks which read their own outputs and list the folders holding them, so they also hit on a clean checkout.

Closes #908.

🤖 Generated with Claude Code

---

Note

Medium Risk
Changes cross-platform fspy hooks and post-run fingerprint/output archiving; incorrect rename handling could cause stale cache hits or missed restores, but scope is filesystem tracking rather than auth or data exfiltration.

Overview
File-access tracking now records rename destinations as RenameTarget and hard-link destinations as writes, on Unix (preload + seccomp), Windows (NtSetInformationFile), with IPC/schema updates and tests. Destinations are logged even when the syscall fails.

Cache behavior treats a renamed file as written output; a renamed folder expands to every file/symlink underneath for archiving and “rebuildable” input logic. Spurious folder write records from opening a directory for write are ignored so reads of that folder still fingerprint correctly.

Adds vtt fs rename, e2e coverage for folder rename-into-place (Vite-style deps), a Vitest fsModuleCache fixture, and a changelog entry: cache hits restore and tolerate missing rename/hard-link outputs on a clean checkout.

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[github-actions]

fspy benchmark

linux

dynamic/launch             change  +0.76%  [ -1.70% ..  +3.32%]  overhead   +54.64%
dynamic/access             change  -1.70%  [ -4.43% ..  +2.16%]  overhead   +19.62%
dynamic/access-relative    change  -1.46%  [ -4.00% ..  +0.31%]  overhead   +68.36%
dynamic/access-contended   change  +2.56%  [ -2.16% ..  +6.05%]  overhead   +46.28%
static/launch              change  +2.01%  [ -0.67% ..  +4.44%]  overhead  +194.89%
static/access              change  +0.00%  [ -0.68% ..  +0.57%]  overhead +1429.00%
static/access-relative     change  +0.05%  [ -0.71% ..  +1.22%]  overhead +1945.71%
static/access-contended    change  -0.07%  [ -1.04% ..  +1.17%]  overhead +1869.27%

macos

dynamic/launch             change  +1.13%  [ -4.30% ..  +7.55%]  overhead  +253.46%
dynamic/access             change  -0.74%  [-53.66% .. +15.89%]  overhead    +0.78%
dynamic/access-relative    change  -1.94%  [-13.77% ..  +5.14%]  overhead  +249.47%
dynamic/access-contended   change  +1.06%  [-11.24% .. +18.38%]  overhead    +3.03%

windows

dynamic/launch             change  -0.33%  [ -5.01% ..  +3.96%]  overhead   +25.15%
dynamic/access             change  +0.00%  [ -2.58% ..  +1.11%]  overhead    +1.52%
dynamic/access-relative    change  +0.00%  [ -1.99% ..  +1.09%]  overhead    +1.29%
dynamic/access-contended   change  +0.71%  [ -6.44% ..  +8.32%]  overhead    +2.91%

[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

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[cursor]

Failed folder rename steals existing tree

Medium Severity

Rename destinations are recorded before the syscall, and any path that is a directory after the run is expanded into written. When the rename fails and that directory already existed, every file under it is treated as a rebuildable output even though the task did not place it there.

 

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