Bug Description

When a gateway session ends (e.g. gateway process restart, Discord bot reconnection, idle timeout), the conversation history is not preserved in the Hindsight memory system. After the session restarts, the agent responds with "抱歉，找不到相關的對話記錄" even though the previous conversation was active.

This is not the same as the /new or /reset bug fixed in #7759. That issue was about /new and /reset not triggering memory provider shutdown. This issue is about the gateway restart path specifically — which does call shutdown_memory_provider(), but passes an empty list.

Root Cause Analysis

Two compounding problems:

1. shutdown_memory_provider() is called without session messages

In gateway/run.py (main, line 1767–1768):

if hasattr(agent, "shutdown_memory_provider"):
    agent.shutdown_memory_provider()   # ← no messages passed

The method signature in run_agent.py (line 3959):

def shutdown_memory_provider(self, messages: list = None) -> None:

Because no messages are passed, on_session_end([]) is called on all memory providers, and any provider that tries to extract facts from the session's conversation gets an empty list. Providers like Holographic (on_session_end([])) have an early return guard:

if not messages:
    return

2. Hindsight has no on_session_end or on_pre_compress hook

The Hindsight plugin (plugins/memory/hindsight/) only implements:

• arecall — injects memories when a session starts
• No on_session_end hook
• No on_pre_compress hook

This means even if messages were passed correctly, Hindsight would still not save anything at session end. The only way Hindsight retains content is via the retain tool — which requires the agent to explicitly call it.

Impact

• Every gateway restart wipes the session's conversational memory from Hindsight's perspective
• Users with long-running sessions that span multiple days lose context after any gateway restart
• The compression summary (generated by on_pre_compress) is session-local and is not written to Hindsight
• The on_session_finalize hook (mentioned in docs) is also not fired on idle timeout ([Bug]: The on_session_finalize hook is not being fired when gateway sessions expire due to configured idle time. #14981)

Expected Behavior

When a gateway session ends, the memory provider should:

1. Receive the full session message list via on_session_end(messages)
2. Extract key facts and save them to Hindsight
3. On next session start, arecall should surface relevant memories

Suggested Fix (two parts)

Part A — Pass messages to shutdown_memory_provider

In gateway/run.py, change:

agent.shutdown_memory_provider()

to:

agent.shutdown_memory_provider(conversation_messages)

This requires tracking conversation_messages in the gateway session context and passing it at shutdown time.

Part B — Implement on_session_end in Hindsight plugin

The Hindsight plugin should implement on_session_end(messages) (and optionally on_pre_compress) to extract and retain key facts from the session before it is discarded.

Related Issues

• /new and /reset commands don't trigger OpenViking session commit #7759 (closed) — /new and /reset don't trigger memory commit — fixed by e964cfc
• [Bug]: The on_session_finalize hook is not being fired when gateway sessions expire due to configured idle time. #14981 (open) — on_session_finalize hook not fired on idle timeout
• [Bug]: Hindsight sync can race interpreter shutdown after successful one-shot CLI exit #15073 (open) — Hindsight sync races interpreter shutdown