The all-profiles sidebar polls GET /api/profiles/projects/tree, the one
heavy sidebar endpoint that was not wrapped in @_sidebar_singleflight_cache.
Every poll fanned out list_profiles() + _build_project_tree() over every
profile (51 on this box, ~17k SKILL.md files walked), and each profile
resolution re-parsed its config.yaml because read_user_config_raw() ran
uncached. On a 2-vCore VPS running 'hermes serve' for the Desktop remote
backend this pinned both cores (py-spy: 110-116% sustained, HostHighCPU).
- Wrap get_profiles_projects_tree in the existing single-flight cache,
matching get_profiles_sessions_sidebar (5s TTL, errors[] not cached).
- Memoize read_user_config_raw() on a (st_dev, st_ino, st_size,
st_mtime_ns) fingerprint under _CONFIG_LOCK, same strategy as
read_raw_config(). Hits return a deepcopy so write-back round-trips keep
their fresh-dict semantics; parse errors are never cached; the docstring
no longer claims 'no caching'.
- Tests: memo semantics (deepcopy isolation, inode-replace reparse, error
non-caching, parse-count), a wrapper-presence pin for both heavy sidebar
endpoints, and a cold-cache autouse fixture in the scope tests (the 5s
TTL otherwise leaks one test's payload into the next).
Measured on the affected box: list_profiles 1.9s -> 0.16s warm, serve CPU
112% -> 22-34%, host CPU 50-70% -> ~26%.
moken627-hub
35af06c009