openclaw - 💡(How to fix) Fix Bug: isolatedSession: true does not isolate heartbeat conversation — context accumulates across runs [1 comments, 1 participants]

Description

When isolatedSession: true is set on agents.defaults.heartbeat, the documentation states each heartbeat run should use a "fresh session with no prior conversation history" and reduce token cost from ~100K to ~2-5K per run.

In practice, the heartbeat session (sessionKey agent:main:main:heartbeat) maps to the same LCM conversation (conversation=3) as the main session. Each heartbeat run's input/output is appended to the shared conversation history, causing unbounded context growth.

Observed behavior

• Heartbeat configured with isolatedSession: true, lightContext: true, every: "30m"
• LCM conversation context grows across runs instead of resetting:
  • 09:22 → 171 items / ~101K tokens
  • 19:52 → 252 items / ~115K tokens
  • 20:02 → 539 items / ~130K tokens (duplicate session started here)
  • 22:32 → 1,431 items / ~174K tokens
  • Post-reset → grew again to 2,867 items / ~83K tokens
• LCM logs show sessionKey=agent:main:main:heartbeat resolving to conversation=3
• A timeout occurred when the accumulated context reached ~83K tokens (via OpenRouter free tier)

Expected behavior

Per the docs:

isolatedSession: when true, each heartbeat runs in a fresh session with no prior conversation history. Uses the same isolation pattern as cron sessionTarget: "isolated". Dramatically reduces per-heartbeat token cost.

Each heartbeat run should start with a clean context, not accumulate history from prior runs.

Steps to reproduce

1. Configure heartbeat:

   {
     "agents": {
       "defaults": {
         "heartbeat": {
           "every": "30m",
           "isolatedSession": true,
           "lightContext": true,
           "target": "none"
         }
       }
     }
   }

2. Let heartbeat run for several hours
3. Check LCM logs for conversation=N and contextItems= in the assemble: done entries for the heartbeat session
4. Observe that context items grow across runs instead of remaining small/flat

Environment

• OpenClaw version: v2026.4.9
• OS: Ubuntu 24.04.4 bare-metal
• Heartbeat model: MiMo flash (OpenRouter), later switched to Nemotron free
• Lossless-claw plugin active

Additional context

• There were also duplicate heartbeat sessions (two runs within 0-2 minutes of each other), possibly triggered by config reloads restarting the heartbeat timer without cancelling the old one. This compounded the accumulation rate but is a separate issue.
• The #admins Discord channel heartbeat conversation stayed small (12 items), suggesting the issue may be specific to how the main session conversation is shared.