hermes - 💡(How to fix) Fix bug(memory): OpenViking plugin never updates _session_id on session rotation (/new, /reset, /resume) [1 pull requests]

Bug Description

The OpenViking memory plugin (plugins/memory/openviking/__init__.py) fails to implement MemoryProvider.on_session_switch(), causing self._session_id to become permanently stale after any agent session rotation. All subsequent sync_turn() writes and the final on_session_end() commit target the original session ID instead of the new one, silently corrupting the session data on the OpenViking server.

Impact

After using /new, /reset, /resume, /branch, or undergoing context compression in a session that uses the OpenViking memory provider:

1. All turn-level messages (sync_turn) are written to the previous session on the OpenViking server
2. The final commit (on_session_end) commits the wrong session, leaving the current session's data invisible in OpenViking
3. The current session appears to have zero messages in OpenViking since its session_id was never used
4. Previously committed sessions get "updated" with the new session's data, corrupting their records

In one observed case, a session with 172 messages was never created on the OpenViking server, while the preceding orphaned session was double-committed with 8 accumulated turns.

Root Cause

The base class MemoryProvider at agent/memory_provider.py:199 defines on_session_switch() as a no-op with explicit documentation:

"Providers that cache per-session state in initialize() (_session_id, _document_id, accumulated turn buffers, counters) should update or reset that state here so subsequent writes land in the correct session's record."

The OpenViking provider caches self._session_id in initialize() at line 475 and increments _turn_count in sync_turn() at line 573, but never overrides on_session_switch() to keep these in sync after session rotation.

Steps to Reproduce

1. Configure Hermes with memory.provider: openviking
2. Start a CLI session (Session A)
3. Type /new to create Session B
4. Send several messages in Session B
5. Type /new again to create Session C
6. Observe that Session B's messages were never committed to OpenViking, while Session A was double-committed with Session B's data appended

Expected Behavior

Each session's messages should be written to and committed under the correct session_id on the OpenViking server, regardless of session rotation events.

Proposed Fix

Override on_session_switch() in the OpenViking provider to update self._session_id and, when reset=True, reset _turn_count to 0:

def on_session_switch(
    self,
    new_session_id: str,
    *,
    parent_session_id: str = "",
    reset: bool = False,
    **kwargs,
) -> None:
    if not new_session_id:
        return
    self._session_id = new_session_id
    if reset:
        self._turn_count = 0

I have verified this fix locally — it resolves the issue by ensuring all subsequent writes land in the correct session's record.

Environment

• Hermes agent version: Current main (June 2026)
• OpenViking server: v0.3.3 (localhost)
• OS: Linux (Ubuntu)
• Reproduced on: CLI interactive mode with /new command

Additional Context

The bug is exclusively in the Hermes OpenViking plugin — the OpenViking server itself handles the API correctly. Other memory providers (Honcho, Hindsight) likely have similar issues since they also override on_session_switch — but this was only verified for OpenViking.