PR #14157 added control-plane write-deny against the ACTIVE HERMES_HOME,
which is fine in non-profile mode but leaves a gap once a profile is
active: HERMES_HOME points at <root>/profiles/<name>, so the global
<root>/auth.json + <root>/config.yaml + <root>/webhook_subscriptions.json
+ <root>/mcp-tokens/ remain writable. Same shape as the .env gap PR
#15981 closed via _hermes_root_path().
Apply the same widening pattern here. The control-file/mcp-tokens check
now iterates BOTH _hermes_home_path() and _hermes_root_path() (dedupes
when they coincide in non-profile mode). Also tightens the mcp-tokens
check from "startswith dir + os.sep" to "==dir OR startswith dir + os.sep"
so writing the directory entry itself is blocked, not just files inside.
Regression tests cover both protections in a real profile-mode layout
(<tmp>/hermes/profiles/coder as HERMES_HOME, <tmp>/hermes as root).
Adds active-HERMES_HOME control-plane files to the write deny list:
auth.json, config.yaml, webhook_subscriptions.json, and any path
under mcp-tokens/. realpath() resolves before comparison so
directory-traversal and symlink targets are normalised, preventing
trivial deny-list bypass via ../ tricks.
Without this, a prompt-injected agent could rewrite Hermes' own
auth state or routing config via write_file / patch — without
triggering the terminal dangerous-command approval — and persist
attacker-controlled behaviour across sessions.
Fixes#14072
build_write_denied_paths() resolved the protected ``.env`` via
get_hermes_home(), which is profile-aware. When a profile is active
HERMES_HOME points at ``<root>/profiles/<name>`` and ``hermes_home / ".env"``
expands to the *profile* env file only — the global ``<root>/.env`` is left
off the deny list and a write_file call against it succeeds. Since the
top-level .env supplies credentials inherited by every profile, this is a
P0 credential-exfiltration / overwrite path.
Add a parallel ``_hermes_root_path()`` helper that returns the Hermes root
(via the existing ``get_default_hermes_root()`` constant) and include
``<root>/.env`` in the deny list alongside ``<active_profile>/.env``. Both
paths now refuse write_file/patch regardless of profile state. The active
HERMES_HOME .env entry is preserved so the protection in non-profile mode
is unchanged.
A regression test exercises the profile-active scenario by pointing
HERMES_HOME at ``<tmp>/profiles/coder`` and asserting that ``<tmp>/.env``
is denied.
Fixes#15981
