fix(mcp): move uv/uvx known-dir table into hermes_platform resolver

The #37589 uv/uvx fallback spelled its directory table (~/.local/bin,
/opt/homebrew/bin, /usr/local/bin) inline in _launcher_fallback, which the
managed-runtime ratchet flags as an unreviewed known_path_table outside
hermes_platform/. known_dirs is the module whose contract is 'every table in
Hermes lives here', so add uv_tool_dirs() there and compose it at the call
site. Behavior is unchanged: same four directories probed in the same order
(managed <home>/bin first, then uv's install order), bare uv/uvx still
resolves under a GUI-style PATH that lacks them.

hermes_platform/resolver/known_dirs.py

@@ -25,6 +25,17 @@ def rust_tool_dirs() -> tuple[str, ...]:
     return ("~/.cargo/bin",) if _POSIX else ("%USERPROFILE%/.cargo/bin",)
 
 
+def uv_tool_dirs() -> tuple[str, ...]:
+    """uv's install locations outside PATH, in uv's own install order: the per-user
+    installer's ``~/.local/bin`` (every OS — that is where uv's docs put it), then
+    Homebrew (Apple Silicon ``/opt``, Intel / from-source ``/usr/local``). The tilde
+    form is deliberate: callers that only ``expanduser`` (the stdio launcher
+    fallback) get the same result as ``locate_command``'s expandvars+expanduser."""
+    if _POSIX:
+        return ("~/.local/bin", "/opt/homebrew/bin", "/usr/local/bin")
+    return ("~/.local/bin",)
+
+
 def node_tool_dirs() -> tuple[str, ...]:
     return ("~/.npm-global/bin", "~/.bun/bin", "~/.volta/bin") if _POSIX else ("%APPDATA%/npm", "%USERPROFILE%/.bun/bin", "%LOCALAPPDATA%/Volta/bin")
 

tools/mcp_tool_config.py

@@ -172,18 +172,18 @@ def _launcher_fallback(command: str, *, windows: Optional[bool] = None) -> str:
     ``uv``/``uvx``: GUI launches (the Electron desktop app, macOS LaunchAgents) inherit the bare
     ``/usr/bin:/bin:/usr/sbin:/sbin`` PATH, which carries none of uv's install locations, so a bare
     ``command: uvx`` MCP server fails with ENOENT at ``execvp`` from Desktop even though it works
-    from an interactive terminal (#37589). Probed in the order uv's own docs install it: the
+    from an interactive terminal (#37589). The directory table lives in
-    Hermes-managed ``<home>/bin`` first, then the per-user installer's ``~/.local/bin``, then
+    ``hermes_platform.resolver.known_dirs.uv_tool_dirs`` (probed in the order uv's own docs install
-    Homebrew (Apple Silicon ``/opt``, Intel ``/usr/local``)."""
+    it: the per-user installer first, then Homebrew); the Hermes-managed ``<home>/bin`` is probed
+    before it."""
     from hermes_constants import get_hermes_home
+    from hermes_platform.resolver.known_dirs import uv_tool_dirs
     home = os.path.expanduser("~")
     if command in {"uv", "uvx"}:
-        directories = [
+        # expanduser: the table carries the ``~`` form so both this walk and
-            os.path.join(str(get_hermes_home()), "bin"),
+        # locate_command's expandvars+expanduser agree on one spelling.
-            os.path.join(home, ".local", "bin"),  # uv's official installer
+        directories = [os.path.join(str(get_hermes_home()), "bin"),
-            os.path.join(os.sep, "opt", "homebrew", "bin"),  # Apple Silicon Homebrew
+                       *(os.path.expanduser(d) for d in uv_tool_dirs())]
-            os.path.join(os.sep, "usr", "local", "bin"),  # Intel Homebrew / from-source
-        ]
     else:
         from hermes_constants import iter_hermes_node_dirs
         # /usr/local/bin: canonical Node location (from-source Linux, Hermes Docker image, Intel