diff --git a/hermes_state_sessions.py b/hermes_state_sessions.py
index 12da656034..74c861e660 100644
--- a/hermes_state_sessions.py
+++ b/hermes_state_sessions.py
@@ -680,14 +680,7 @@ class SessionSessionsMixin:
         """Set the model after a mid-session /model switch (unconditionally) and drop any Browser
         runtime lock (lineage markers survive).
 
-        The stored system prompt is deliberately PRESERVED: it is the session's provider cache
-        prefix, and a rebuilt prompt never matches those bytes — clearing the row re-bills the whole
-        prefix on a commit that may not even have moved the route (the picker re-committing the
-        session's current model), and the next turn then reads a NULL row and takes the broken-row
-        branch in ``agent.conversation_loop`` (a WARNING blaming the previous turn's
-        ``update_system_prompt`` write path). The stale ``Model:``/``Provider:`` footer this used to
-        null the row for is caught by ``_stored_prompt_matches_runtime`` on the next turn: a real
-        switch rebuilds there (INFO, then re-persists), a same-route commit reuses the bytes.
+        Route writers never touch the stored prompt; ``_stored_prompt_matches_runtime`` decides staleness.
 
         When *provider* is given the whole route is written, in both shapes resume reads (top-level
         keys for the TUI/Desktop, ``gateway_runtime`` for the CLI), so a later resume recombines the
@@ -761,9 +754,7 @@ class SessionSessionsMixin:
         confirmed: bool = False,
     ) -> None:
         """Persist a Browser / API-client runtime lock into model_config (lineage markers survive).
-        The stored system prompt stays: a lock that moves the model is caught by the next turn's
-        ``_stored_prompt_matches_runtime`` identity check, and one that does not must keep the
-        session's cache prefix byte-identical."""
+        Route writers never touch the stored prompt; ``_stored_prompt_matches_runtime`` decides staleness."""
         lock = {
             "provider": provider or "", "model": model or "", "model_options": model_options or {},
             "route_source": route_source or "", "confirmed": bool(confirmed), "updated_at": time.time(),
diff --git a/hermes_state_usage.py b/hermes_state_usage.py
index 41de7e4616..0b2e2fe991 100644
--- a/hermes_state_usage.py
+++ b/hermes_state_usage.py
@@ -88,9 +88,7 @@ class SessionUsageMixin:
         """Unconditionally set the billing route (``update_token_counts`` only COALESCE-fills
         NULLs) so the dashboard reflects the latest /model switch.
 
-        The stored system prompt is left alone — it is the session's cache prefix and the route
-        change is caught by the next turn's ``_stored_prompt_matches_runtime`` identity check, which
-        rebuilds only when the footer it embeds is actually stale.
+        Route writers never touch the stored prompt; ``_stored_prompt_matches_runtime`` decides staleness.
 
         See #48173, #48248.
         """