From 6c2a94f4b634dbbdce09e5ff26b88bcfbd845198 Mon Sep 17 00:00:00 2001
From: teknium1 <127238744+teknium1@users.noreply.github.com>
Date: Wed, 23 Sep 2026 04:43:48 -0700
Subject: [PATCH] fix(tui-gateway): stale session_id is refused once at the
 config.set seam for every session-scoped key

Sweep of the #119983 shape: `reasoning` had the same stale-session -> global-write
fall-through as `fast`/`yolo` (a reaped session_id wrote agent.reasoning_effort into
config.yaml and answered success), and `model` already carried its own 4001. One check
at the dispatcher replaces the three per-handler guards: a non-empty session_id this
backend no longer holds, on a key whose sessionless branch writes a wider scope
(config.yaml agent.*, the process env every later child inherits), answers 4001 so
the client resumes. `scope="global"` is still honoured; a request with no session_id
at all is still the sessionless path.

Live (temp home, stale id): base wrote reasoning_effort: high and HERMES_YOLO_MODE=1;
head leaves config.yaml and os.environ byte-identical and answers 4001 for all three.
---
 tui_gateway/methods_config_set.py | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/tui_gateway/methods_config_set.py b/tui_gateway/methods_config_set.py
index be03c00edb..7e5f2d4ffc 100644
--- a/tui_gateway/methods_config_set.py
+++ b/tui_gateway/methods_config_set.py
@@ -162,10 +162,6 @@ _FAST_WORDS = {"fast": "fast", "on": "fast", "normal": "normal", "off": "normal"
 
 
 def _set_fast(rid, params, key, value, session):
-    if session is None and params.get("session_id"):
-        # A runtime id this backend no longer holds (reaped / re-minted) must not reach the sessionless
-        # branch: it persists agent.service_tier for every surface. 4001 lets the client resume it.
-        return _sess_nowait(params, rid)[1]
     raw = _word(value)
     agent = session.get("agent") if session else None
     if agent is not None:
@@ -282,10 +278,6 @@ def _set_yolo(rid, params, key, value, session):
         enable = _BOOL_WORDS.get(raw, not is_session_yolo_enabled(skey))
         (enable_session_yolo if enable else disable_session_yolo)(skey)
         _emit_session_info(params.get("session_id", ""), session)
-    elif params.get("session_id"):
-        # Stale runtime id: the process flag below never reaches this session's approvals, yet every
-        # child spawned afterwards (compute host, a terminal's `hermes`) inherits the flip.
-        return _sess_nowait(params, rid)[1]
     else:
         enable = _BOOL_WORDS.get(raw, not is_truthy_value(os.environ.get("HERMES_YOLO_MODE")))
         if enable:
@@ -479,12 +471,21 @@ _CONFIG_SETTERS = {
     "cwd": _set_cwd, "terminal.cwd": _set_cwd, "workdir": _set_cwd,
     "prompt": _set_prompt, "personality": _set_personality, "skin": _set_skin}
 
+# Keys whose sessionless branch writes a different, wider scope than the session branch (config.yaml's
+# agent.* for every surface, the process env every later child inherits). A non-empty session_id this
+# backend no longer holds (reaped / re-minted) is a stale session, not "no session": it answers 4001 so
+# the client resumes, never the global write. An explicit scope="global" is still honoured.
+_SESSION_SCOPED_KEYS = frozenset({"model", "fast", "yolo", "reasoning"})
+
 
 @method("config.set")
 @_profile_scoped
 def _(rid, params: dict) -> dict:
     key, value = params.get("key", ""), params.get("value", "")
     session = _sessions.get(params.get("session_id", ""))
+    if session is None and params.get("session_id") and key in _SESSION_SCOPED_KEYS \
+            and _word(params.get("scope")) != "global":
+        return _sess_nowait(params, rid)[1]
     handler = _CONFIG_SETTERS.get(key)
     if handler is None and key.startswith("details_mode."):
         handler = _set_details_section