* fix(gateway): bound _agent_cache with LRU cap + idle TTL eviction
The per-session AIAgent cache was unbounded. Each cached AIAgent holds
LLM clients, tool schemas, memory providers, and a conversation buffer.
In a long-lived gateway serving many chats/threads, cached agents
accumulated indefinitely — entries were only evicted on /new, /model,
or session reset.
Changes:
- Cache is now an OrderedDict so we can pop least-recently-used entries.
- _enforce_agent_cache_cap() pops entries beyond _AGENT_CACHE_MAX_SIZE=64
when a new agent is inserted. LRU order is refreshed via move_to_end()
on cache hits.
- _sweep_idle_cached_agents() evicts entries whose AIAgent has been idle
longer than _AGENT_CACHE_IDLE_TTL_SECS=3600s. Runs from the existing
_session_expiry_watcher so no new background task is created.
- The expiry watcher now also pops the cache entry after calling
_cleanup_agent_resources on a flushed session — previously the agent
was shut down but its reference stayed in the cache dict.
- Evicted agents have _cleanup_agent_resources() called on a daemon
thread so the cache lock isn't held during slow teardown.
Both tuning constants live at module scope so tests can monkeypatch
them without touching class state.
Tests: 7 new cases in test_agent_cache.py covering LRU eviction,
move_to_end refresh, cleanup thread dispatch, idle TTL sweep,
defensive handling of agents without _last_activity_ts, and plain-dict
test fixture tolerance.
* tweak: bump _AGENT_CACHE_MAX_SIZE 64 -> 128
* fix(gateway): never evict mid-turn agents; live spillover tests
The prior commit could tear down an active agent if its session_key
happened to be LRU when the cap was exceeded. AIAgent.close() kills
process_registry entries for the task, tears down the terminal
sandbox, closes the OpenAI client (sets self.client = None), and
cascades .close() into any active child subagents — all fatal if
the agent is still processing a turn.
Changes:
- _enforce_agent_cache_cap and _sweep_idle_cached_agents now look at
GatewayRunner._running_agents and skip any entry whose AIAgent
instance is present (identity via id(), so MagicMock doesn't
confuse lookup in tests). _AGENT_PENDING_SENTINEL is treated
as 'not active' since no real agent exists yet.
- Eviction only considers the LRU-excess window (first size-cap
entries). If an excess slot is held by a mid-turn agent, we skip
it WITHOUT compensating by evicting a newer entry. A freshly
inserted session (zero cache history) shouldn't be punished to
protect a long-lived one that happens to be busy.
- Cache may therefore stay transiently over cap when load spikes;
a WARNING is logged so operators can see it, and the next insert
re-runs the check after some turns have finished.
New tests (TestAgentCacheActiveSafety + TestAgentCacheSpilloverLive):
- Active LRU entry is skipped; no newer entry compensated
- Mixed active/idle excess window: only idle slots go
- All-active cache: no eviction, WARNING logged, all clients intact
- _AGENT_PENDING_SENTINEL doesn't block other evictions
- Idle-TTL sweep skips active agents
- End-to-end: active agent's .client survives eviction attempt
- Live fill-to-cap with real AIAgents, then spillover
- Live: CAP=4 all active + 1 newcomer — cache grows to 5, no teardown
- Live: 8 threads racing 160 inserts into CAP=16 — settles at 16
- Live: evicted session's next turn gets a fresh agent that works
30 tests pass (13 pre-existing + 17 new). Related gateway suites
(model switch, session reset, proxy, etc.) all green.
* fix(gateway): cache eviction preserves per-task state for session resume
The prior commits called AIAgent.close() on cache-evicted agents, which
tears down process_registry entries, terminal sandbox, and browser
daemon for that task_id — permanently. Fine for session-expiry (session
ended), wrong for cache eviction (session may resume).
Real-world scenario: a user leaves a Telegram session open for 2+ hours,
idle TTL evicts the cached AIAgent, user returns and sends a message.
Conversation history is preserved via SessionStore, but their terminal
sandbox (cwd, env vars, bg shells) and browser state were destroyed.
Fix: split the two cleanup modes.
close() Full teardown — session ended. Kills bg procs,
tears down terminal sandbox + browser daemon,
closes LLM client. Used by session-expiry,
/new, /reset (unchanged).
release_clients() Soft cleanup — session may resume. Closes
LLM client only. Leaves process_registry,
terminal sandbox, browser daemon intact
for the resuming agent to inherit via
shared task_id.
Gateway cache eviction (_enforce_agent_cache_cap, _sweep_idle_cached_agents)
now dispatches _release_evicted_agent_soft on the daemon thread instead
of _cleanup_agent_resources. All session-expiry call sites of
_cleanup_agent_resources are unchanged.
Tests (TestAgentCacheIdleResume, 5 new cases):
- release_clients does NOT call process_registry.kill_all
- release_clients does NOT call cleanup_vm / cleanup_browser
- release_clients DOES close the LLM client (agent.client is None after)
- close() vs release_clients() — semantic contract pinned
- Idle-evicted session's rebuild with same session_id gets same task_id
Updated test_cap_triggers_cleanup_thread to assert the soft path fires
and the hard path does NOT.
35 tests pass in test_agent_cache.py; 67 related tests green.
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