`hermes_home_key` called `Path.resolve()` on every call, which is a
filesystem call. `ToolRegistry.current_scope_key()` calls it, and
`_merged_tools()` calls that, so every single registry lookup went to
the disk: `get_entry`, `get_toolset_for_tool`, `get_emoji`, and the rest.
Anything that looks up many tools in a row paid for it. Building the
deferred-tool catalog for `tool_search` calls `get_entry` once per tool,
so with 400 deferrable tools one search did 800 path resolutions. On
Windows that is `nt._getfinalpathname`, and it took 132ms of the 148ms
the catalog build spent. The tokenizing everyone would suspect first was
under 4ms of it.
The resolved value is now remembered per input path. A process only sees
a handful of home paths, so the dict stays tiny. Measured on the same
400-tool catalog build, the lookups drop from 132ms to 3.1ms with one
entry cached.
A path that does not exist yet is resolved but not remembered, because
the answer can change once it is created, for instance when part of the
path turns out to be a link. A different home path is a different key,
so switching profiles or `HERMES_HOME` gets its own entry rather than
reusing a stale one.
Adolanium