fix: scope session search handoff recall

[a249169329-cpu]

Summary

• Scope session_search previous/handoff recall to the current gateway/session boundary when requested.
• Persist gateway identity metadata (user_id_alt, chat/thread/session key) on session rows so recall filtering can distinguish QQ chats/threads.
• Add regression coverage for current-scope handoff/previous recall and cross-chat isolation.

Verification

• git diff --check
• python3 -m pytest tests/tools/test_session_search.py tests/test_hermes_state.py -o addopts='' -q → 275 passed
• Expanded session/gateway/compression suite → 487 passed
• python3 scripts/check-windows-footguns.py --all
• python3 -m py_compile agent/tool_executor.py gateway/session.py hermes_state.py run_agent.py tools/session_search_tool.py tools/process_registry.py

Notes

• Rebuilt from current NousResearch/main to avoid the stale fork-main diff pollution that affected PR Support passing morph snapshot id #2.
• The old fork branch fix/session-search-scope-handoff is preserved; PR Support passing morph snapshot id #2 was closed without deleting it.

[teknium1]

Thanks for the focused current-chat recall design and the regression coverage.

Problems

• The new scope payload is wired only through the sequential dispatcher (agent/tool_executor.py:720-730 in this PR). Current main’s concurrent path dispatches session_search through agent/agent_runtime_helpers.py:2260-2278, where only db and current_session_id are forwarded; concurrent calls would therefore remain globally scoped.
• Current main added exact-title retrieval after this branch. tools/session_search_tool.py:499-553 resolves and appends a title result before the FTS filtering loop. The proposed filtering at this PR’s tools/session_search_tool.py:558-565 would not constrain a matching title from another chat after salvage.
• The storage changes are stale relative to current main: hermes_state.py:718-725 already persists most routing fields, and session initialization has moved into agent/agent_init.py.

Suggested changes

• Carry the hidden gateway scope through both execution paths and add a concurrent-dispatch regression.
• Scope exact-title matches as well as FTS, browse, handoff, and scroll paths; add a same-title cross-chat test.
• Adapt persistence changes to the current SessionDB reconciliation and gateway peer APIs.

Automated hermes-sweeper review.

[teknium1]

This only covers the sequential executor. Current main’s concurrent path calls agent_runtime_helpers.invoke_tool() and its session_search branch still forwards only db and current_session_id; please thread this same scope payload through that path and add a concurrent-dispatch regression.

[teknium1]

When salvaging onto current main, apply this scope to exact-title results too: current _discover() resolves and appends _title_match_result() before the FTS-row loop, so filtering only FTS hits still exposes a same-title session from another chat.