diff --git a/gateway/run.py b/gateway/run.py
index fcaffe205a..e14e6958aa 100644
--- a/gateway/run.py
+++ b/gateway/run.py
@@ -2089,7 +2089,8 @@ if not _configured_cwd or _configured_cwd in CWD_PLACEHOLDERS:
 from gateway.config import (
     ChannelOverride, Platform, GatewayConfig, PlatformConfig, _getenv, load_gateway_config)
 from gateway.session import (
-    AsyncSessionStore, SessionStore, SessionSource, SessionContext, build_session_key)
+    AsyncSessionStore, SessionStore, SessionSource, SessionContext, build_session_key,
+    profile_from_session_key_namespace)
 # Telegram topic routing (#22773, regression fixed #52060): a
 # ``telegram:<positive_chat_id>:<numeric_thread_id>`` cron target is ambiguous — a forum-style topic in a
 # private chat and a genuine Bot API channel Direct-Messages topic share the same shape and need OPPOSITE
@@ -2869,7 +2870,8 @@ _PROFILE_ID_KEY_RE = re.compile(r"^[a-z0-9][a-z0-9_-]{0,63}$")
 def _parse_session_key(session_key: str) -> "dict | None":
     """Parse a session key (``agent:{ns}:{platform}:{chat_type}:{chat_id}[:{extra}...]``).
 
-    ``{ns}`` is ``main`` for the default profile or a named-profile id (profile ids match
+    ``{ns}`` is ``main`` for the default profile, ``main~`` for a profile literally named ``main``
+    (``gateway.session._session_key_namespace``), or a named-profile id (profile ids match
     ``[a-z0-9][a-z0-9_-]{0,63}`` — never contain ``:`` — so a plain split stays unambiguous).
     For group/channel sessions the suffix may be a user_id, not a thread_id, so ``thread_id``
     is omitted. Named profiles are reported as ``profile``; ``main`` keys keep their historical
@@ -2879,11 +2881,11 @@ def _parse_session_key(session_key: str) -> "dict | None":
     if (
         len(parts) >= 5
         and parts[0] == "agent"
-        and (parts[1] == "main" or _PROFILE_ID_KEY_RE.match(parts[1]))
+        and (parts[1] in ("main", "main~") or _PROFILE_ID_KEY_RE.match(parts[1]))
     ):
         result = {"platform": parts[2], "chat_type": parts[3], "chat_id": parts[4]}
         if parts[1] != "main":
-            result["profile"] = parts[1]
+            result["profile"] = profile_from_session_key_namespace(parts[1])
         if len(parts) > 5 and parts[3] in {"dm", "thread"}:
             result["thread_id"] = parts[5]
         return result
diff --git a/gateway/run_notifications.py b/gateway/run_notifications.py
index 440db0d8eb..1fa8c80267 100644
--- a/gateway/run_notifications.py
+++ b/gateway/run_notifications.py
@@ -438,9 +438,10 @@ class GatewayNotificationsMixin:
         profile = str(data.get("profile") or "").strip()
         if profile:
             return profile
+        from gateway.session import profile_from_session_key_namespace
         parts = str(data.get("session_key") or "").split(":")
         if len(parts) >= 5 and parts[0] == "agent" and parts[1] not in ("main", ""):
-            return parts[1]
+            return profile_from_session_key_namespace(parts[1])
         return None
 
     def _resolve_update_target(self, paths: "_UpdatePaths") -> Optional["_UpdateTarget"]:
diff --git a/gateway/run_profile_reconcile.py b/gateway/run_profile_reconcile.py
index 4f69115f45..e1ec0c9511 100644
--- a/gateway/run_profile_reconcile.py
+++ b/gateway/run_profile_reconcile.py
@@ -201,7 +201,8 @@ class GatewayProfileReconcileMixin:
             self._served_profile_homes.pop(name, None)
         if isinstance(self._served_profile_signatures, dict):
             self._served_profile_signatures.pop(name, None)
-        prefix = f"agent:{name}:"
+        from gateway.session import _session_key_namespace
+        prefix = _session_key_namespace(name) + ":"
         cache = getattr(self, "_agent_cache", None)
         for key in [k for k in list(cache or {}) if str(k).startswith(prefix)]:
             with _log_suppressed(logging.DEBUG, "agent eviction failed for %s", key, exc_info=True):
diff --git a/gateway/session.py b/gateway/session.py
index 001d27f3b4..fb074d0cc6 100644
--- a/gateway/session.py
+++ b/gateway/session.py
@@ -625,8 +625,21 @@ def is_shared_multi_user_session(
 def _session_key_namespace(profile: Optional[str]) -> str:
     """``agent:<ns>`` prefix for a session key: default/None profile → ``agent:main``
     (BYTE-IDENTICAL to every historical key); named profile → ``agent:<name>`` so two
-    profiles serving the same chat never collide."""
-    return "agent:main" if not profile or profile == "default" else f"agent:{profile}"
+    profiles serving the same chat never collide. A profile literally named ``main`` would
+    otherwise produce the default's namespace and share every session (routing index, agent
+    cache, store) with it, so it is marked ``main~``: ``~`` is outside the profile-id alphabet,
+    so the marked form can never be another profile's id."""
+    if not profile or profile == "default":
+        return "agent:main"
+    return "agent:main~" if profile == "main" else f"agent:{profile}"
+
+
+def profile_from_session_key_namespace(namespace: str) -> str:
+    """Inverse of :func:`_session_key_namespace` for the ``<ns>`` slot of a key: ``"default"`` for
+    ``main``, ``"main"`` for the marked ``main~``, else the slot is the profile id."""
+    if namespace == "main":
+        return "default"
+    return "main" if namespace == "main~" else namespace
 
 
 def _canonical_participant(source: SessionSource) -> Optional[str]:
diff --git a/gateway/session_recovery.py b/gateway/session_recovery.py
index 6fdf48a13b..cfe0a99cb4 100644
--- a/gateway/session_recovery.py
+++ b/gateway/session_recovery.py
@@ -53,8 +53,8 @@ class SessionRecoveryMixin:
         parts = str(session_key).split(":")
         if len(parts) < 2 or parts[0] != "agent":
             return None
-        namespace = parts[1] or "main"
-        return "default" if namespace == "main" else namespace
+        from gateway.session import profile_from_session_key_namespace
+        return profile_from_session_key_namespace(parts[1] or "main")
 
     @staticmethod
     def _active_profile_name() -> str:
diff --git a/tests/gateway/test_multiplex_session_db_profile_scope.py b/tests/gateway/test_multiplex_session_db_profile_scope.py
index fe4b747297..34a2a18975 100644
--- a/tests/gateway/test_multiplex_session_db_profile_scope.py
+++ b/tests/gateway/test_multiplex_session_db_profile_scope.py
@@ -790,3 +790,33 @@ def test_default_namespace_rows_stay_in_launch_store_under_secondary_scope(multi
         reset_hermes_home_override(scope)
 
     assert Path(db.db_path) == root / "state.db"
+
+
+def test_profile_named_main_keeps_its_own_namespace_and_store(multiplex_homes):
+    """``main`` is a valid profile name, but ``agent:main`` is the default profile's namespace: a
+    profile literally named ``main`` produced byte-identical keys to the default and, once default
+    keys were pinned to the launch store, its scoped sessions were written into the ROOT
+    ``state.db``. Its namespace must differ from the default's and resolve back to ``profiles/main``."""
+    from gateway.run import _parse_session_key
+    from gateway.session import build_session_key
+
+    root, _profile = multiplex_homes
+    main_home = root / "profiles" / "main"
+    main_home.mkdir(parents=True)
+    store = _multiplex_store(root)
+    source = SessionSource(platform=Platform.TELEGRAM, chat_id="555", user_id="u1", profile="main")
+
+    main_key = build_session_key(source, profile="main")
+    default_key = build_session_key(source, profile=None)
+    assert main_key != default_key
+    assert store._profile_from_session_key(main_key) == "main"
+    assert store._profile_from_session_key(default_key) == "default"
+    assert _parse_session_key(main_key)["profile"] == "main"
+    assert "profile" not in _parse_session_key(default_key)
+
+    scope = set_hermes_home_override(str(main_home))
+    try:
+        assert Path(store._db_for_key(main_key).db_path) == main_home / "state.db"
+        assert Path(store._db_for_key(default_key).db_path) == root / "state.db"
+    finally:
+        reset_hermes_home_override(scope)
diff --git a/website/docs/user-guide/multi-profile-gateways.md b/website/docs/user-guide/multi-profile-gateways.md
index 3e9f3d381d..cee56c8538 100644
--- a/website/docs/user-guide/multi-profile-gateways.md
+++ b/website/docs/user-guide/multi-profile-gateways.md
@@ -294,7 +294,9 @@ migration, no orphaned history. Every gateway path that reads a key back —
 delegation completions after a restart, shutdown notices, a per-user-thread
 `/stop` of a sibling's run, `/undo`, QQ approval buttons — accepts the
 `agent:<profile>:…` shape too, so secondary profiles get the same behaviour
-as the default one.
+as the default one. The one profile name that would collide with the default's
+namespace, a profile literally called `main`, is keyed `agent:main~:…` so it
+keeps its own sessions and its own `profiles/main/state.db`.
 
 Each profile's rows land in **its own** `state.db`: a named profile's under
 `profiles/<name>/state.db`, the default profile's under the launch home — even