diff --git a/CHANGELOG.md b/CHANGELOG.md
index 34f8099..0405b24 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Hermes Web UI -- Changelog
 
+## [v0.50.155] — 2026-04-22
+
+### Fixed
+- **Honcho per-session memory uses stable session ID across WebUI turns** — `api/streaming.py` now passes `gateway_session_key=session_id` to `AIAgent` (defensive, same pattern as `api_mode`/`credential_pool`). Without this, Honcho's `per-session` strategy created a new Honcho session on each streaming request. (`api/streaming.py`) (closes #855)
+
 ## [v0.50.154] — 2026-04-22
 
 ### Fixed
diff --git a/api/streaming.py b/api/streaming.py
index 13dc5e2..bd67f4d 100644
--- a/api/streaming.py
+++ b/api/streaming.py
@@ -1155,6 +1155,12 @@ def _run_agent_streaming(session_id, msg_text, model, workspace, stream_id, atta
                 _agent_kwargs['acp_args'] = _rt.get('args')
             if 'credential_pool' in _agent_params:
                 _agent_kwargs['credential_pool'] = _rt.get('credential_pool')
+            # Pin Honcho memory sessions to the stable WebUI session ID.
+            # Without this, 'per-session' Honcho strategy creates a new Honcho
+            # session on every streaming request because HonchoSessionManager is
+            # re-instantiated fresh each turn (#855).
+            if 'gateway_session_key' in _agent_params:
+                _agent_kwargs['gateway_session_key'] = session_id
 
             agent = _AIAgent(**_agent_kwargs)