Heartbeat model override is ignored at runtime. The configured heartbeat.model is not respected; heartbeat always falls back to the main session default model.

Environment

• OpenClaw version: v2026.3.28 (commit f9b1079)
• OS: WSL2, Node v22.22.1
• Channel: WhatsApp
• Primary model: minimax/MiniMax-M2.7

Configuration

{
  "agents": {
    "defaults": {
      "heartbeat": {
        "model": "openrouter/arcee-ai/trinity-large-preview:free"
      }
    }
  }
}

Expected Behavior

Heartbeat should use the configured model.

Actual Behavior

Heartbeat requests MiniMax-M2.5 (main session default), cycling through 10 candidates before landing on MiniMax-M2.7:

attempt:1  minimax/MiniMax-M2.5                           failed
attempt:2  openrouter/arcee-ai/trinity-large-preview:free  failed
attempt:3  openrouter/qwen/qwen3-coder:free               failed
attempt:4  openrouter/z-ai/glm-4.5-air:free             failed
attempt:5  openrouter/stepfun/step-3.5-flash:free        failed
attempt:6  ollama/kimi-k2.5:cloud                       failed
attempt:7  ollama/qwen3-coder-next:cloud               failed
attempt:8  ollama/glm-4.7:cloud                       failed
attempt:9  ollama/minimax-m2.7:cloud                   failed
attempt:10 minimax/MiniMax-M2.7                         succeeded

Additional Context

MiniMax deprecated M2, M2.1, M2.5, VL-01 in v2026.3.28, making M2.5 unreliable. This worsens the cascade.

Related

• [Bug] Heartbeat model override still ignored in 2026.2.19 #21144 (closed/locked - same bug in v2026.2.19)
• [Bug]: Different model not being used for heartbeat #14279, Heartbeat ignores heartbeat.model when session has modelOverride #13009, [Bug]: Heartbeat Model Override Not Working in OpenClaw 2026.2.3-1 #9556 (previously fixed, regression)