Bug

The heartbeat.model override works in agents.defaults.heartbeat.model but is ignored when set per-agent in agents.list[].heartbeat.model.

Config Example

{
  "agents": {
    "defaults": {
      "model": { "primary": "anthropic/claude-opus-4-5" }
    },
    "list": [
      {
        "id": "kev",
        "heartbeat": {
          "every": "5m",
          "model": "google/gemini-3-pro-preview"  // ❌ Ignored
        }
      }
    ]
  }
}

Expected

Heartbeat runs for agent kev should use google/gemini-3-pro-preview.

Actual

Heartbeat runs still use anthropic/claude-opus-4-5 (the default model).

Root Cause

In src/auto-reply/reply/get-reply.ts:

const agentCfg = cfg.agents?.defaults;  // ❌ Only reads defaults
// ...
const heartbeatRaw = agentCfg?.heartbeat?.model?.trim() ?? "";

The code reads heartbeat.model only from agents.defaults, never from the resolved per-agent config.

Workaround

Set heartbeat.model in agents.defaults.heartbeat instead of per-agent.

Suggested Fix

Use the merged agent config (with per-agent overrides applied) instead of just cfg.agents?.defaults.