diff --git a/api/profiles.py b/api/profiles.py
index c18cfe9f..b0462108 100644
--- a/api/profiles.py
+++ b/api/profiles.py
@@ -376,10 +376,17 @@ def _resolve_profile_home_for_name(name: str) -> Path:
     names fall back to the base home so traversal-shaped cookie values cannot
     influence filesystem paths.
     """
-    # In isolated mode, the pinned profile name, including a literal
-    # "default", must resolve to the configured startup HERMES_HOME.
-    if _is_isolated_profile_mode() and name == _isolated_profile_name():
-        return Path(_INITIAL_HERMES_HOME).expanduser()
+    # In isolated mode, every logical profile lookup clamps to the configured
+    # startup HERMES_HOME so callers cannot resolve a foreign profile path.
+    if _is_isolated_profile_mode():
+        isolated_name = _isolated_profile_name()
+        isolated_home = Path(_INITIAL_HERMES_HOME).expanduser()
+        if name and not _profiles_match(name, isolated_name):
+            logger.warning(
+                "Ignoring profile lookup %r in isolated profile mode; using pinned profile %r",
+                name, isolated_name,
+            )
+        return isolated_home
     if not name or _is_root_profile(name):
         return _DEFAULT_HERMES_HOME
     if not _PROFILE_ID_RE.fullmatch(name):
diff --git a/tests/test_issue2698_isolated_hermes_home.py b/tests/test_issue2698_isolated_hermes_home.py
index 8b8e3e47..94750b89 100644
--- a/tests/test_issue2698_isolated_hermes_home.py
+++ b/tests/test_issue2698_isolated_hermes_home.py
@@ -291,6 +291,19 @@ class TestIsolatedRuntimePinning:
         assert get_hermes_home_for_profile("default") == isolated_default
         assert get_hermes_home_for_profile("default") != temp_hermes_home
 
+    def test_explicit_foreign_profile_resolution_stays_on_isolated_home(self, temp_single_profile, monkeypatch):
+        """Explicit profile lookups must not escape the isolated startup home."""
+        from api.profiles import get_hermes_home_for_profile, _resolve_profile_home_for_name
+
+        base_home = temp_single_profile.parent.parent
+        monkeypatch.setenv("HERMES_HOME", str(temp_single_profile))
+        monkeypatch.setenv("HERMES_BASE_HOME", "")
+        monkeypatch.setattr(_profiles_mod, "_DEFAULT_HERMES_HOME", base_home)
+        monkeypatch.setattr(_profiles_mod, "_INITIAL_HERMES_HOME", str(temp_single_profile))
+
+        assert _resolve_profile_home_for_name("other_profile") == temp_single_profile
+        assert get_hermes_home_for_profile("other_profile") == temp_single_profile
+
     def test_list_profiles_prefers_matching_isolated_default_home(self, temp_hermes_home, monkeypatch):
         """The isolated profiles/default row must not collapse to the base-home row."""
         isolated_default = temp_hermes_home / "profiles" / "default"