When read_file or search hits a non-existent path, ShellFileOperations
spawns a subprocess to stat the path and another to walk the parent
directory for "did you mean..." suggestions. A typo'd path retried 13
times (observed in the wild) costs 26 subprocess invocations + 13 ls
walks for a result we already know.
Add a per-task negative-result cache keyed by (op, resolved_path) with
a 60s TTL and a hard cap of 500 entries. On hit, return the cached
error JSON immediately and skip the subprocess + suggestion walk.
The cache is namespaced by operation ("read" vs "search") because the
two callers return different error JSON shapes ("File not found:" vs
"Path not found:"). Eviction:
* TTL (60s) — short, so a path that appears later isn't masked.
* write_file / patch on the same path — _invalidate_dedup_for_path
now also drops the negative-cache entry so a freshly-written file
is read from disk on the next call instead of returning a stale
"not found" stub.
Tests in tests/tools/test_file_tools.py cover:
* read cache hit skips the subprocess on retry
* cache is per-task (no cross-task pollution)
* successful reads do not poison the cache
* search cache hit skips the subprocess on retry
* read and search caches are namespaced (different error shapes)
* write_file invalidates the read negative cache
* TTL expiry evicts stale entries
Kent
acfb40c9c7