agent.model override does not apply to built-in subagents (general, explore)

[fs-bmedkouri]

Bug

The agent.model config override in opencode.jsonc does not take effect for built-in subagents (general, explore). They inherit the primary model regardless of the configured override.

Reproduction

1. Set the primary model to Opus 4 (claude-opus-4-6)
2. Add the following to opencode.jsonc:

"agent": {
  "general": {
    "model": "anthropic/claude-sonnet-4-20250514"
  },
  "explore": {
    "model": "anthropic/claude-sonnet-4-20250514"
  }
}

3. Start a new OpenCode session (confirmed config is loaded at session start)
4. Invoke a Task tool that uses the explore subagent
5. Query the local API: GET /session/{subagent-session-id}/message

Expected

The subagent assistant message shows "modelID": "claude-sonnet-4-20250514"

Actual

The subagent assistant message shows "modelID": "claude-opus-4-6" -- the primary model, not the configured override.

API response excerpt:

{
  "modelID": "claude-opus-4-6",
  "providerID": "anthropic",
  "cost": 0.084715,
  "tokens": { "total": 13492, "input": 3, "output": 21, "cache": { "write": 13468, "read": 0 } }
}

The cost ($0.085 for ~13.5k tokens) confirms Opus pricing, not Sonnet.

Verification

• Config syntax is correct (matches docs examples exactly)
• Config parses successfully (validated with PowerShell JSON parser)
• This is a fresh session (not a mid-session config change)
• The small_model config in the same file does work

Environment

• OpenCode v1.4.3
• Windows 11
• Provider: Anthropic (direct)
• Primary model: claude-opus-4-6

Docs reference

https://opencode.ai/docs/agents#model shows this should work:

{
  "agent": {
    "plan": {
      "model": "anthropic/claude-haiku-4-20250514"
    }
  }
}

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• subagent model variants are parsed but not applied at runtime in v1.4.0 #21632: subagent model variants parsed but not applied at runtime in v1.4.0 — same symptom (agent model config ignored at subagent runtime despite correct config resolution)
• [Bug] Model parameter ignored when launching subagent with agent name #18615: model parameter ignored when launching subagent with agent name — related (model override not respected for built-in subagents)
• Subagent models are ignored when using GitHub Copilot provider — All Premium Requests billed to orchestrator model (Claude Opus 4.6) #20859: subagent models ignored with GitHub Copilot provider — similar symptom (primary model used instead of configured subagent model)

If your issue is distinct from these, please mention what differentiates it.

[OpeOginni]

Hey I am not able to reproduce this issue, following the exact same config and flow you are. Can you confirm you are using the correct session ID for the subagent?