Description

The channels.modelByChannel feature is documented in the configuration reference but fails schema validation when added to the config file.

Steps to Reproduce

1. Add the following to ~/.openclaw/openclaw.json:

{
  "channels": {
    "modelByChannel": {
      "telegram": {
        "-1003588664547": "custom-anthropic/claude-opus-4-6",
        "-1003588664547:topic:2": "xopglm/xopglm5"
      }
    }
  }
}

2. Run any openclaw command

3. Get error:

Invalid config at /Users/wf/.openclaw/openclaw.json:
- channels.modelByChannel: unknown channel id: modelByChannel

Expected Behavior

The config should be accepted and per-topic model overrides should work as documented in:

• /docs/gateway/configuration-reference.md (Channel model overrides section)
• /docs/channels/telegram.md (Forum topics section)

Actual Behavior

Schema validation rejects modelByChannel as an unknown channel id.

Environment

• OpenClaw version: 2026.2.21-2
• OS: macOS (Darwin 25.3.0 arm64)
• Node: v25.5.0

Additional Context

The feature appears to be implemented in the codebase (found references in subagent-registry-*.js), but the JSON schema does not include modelByChannel as a valid property under channels.

This is a useful feature for users who want different models for different Telegram topics (e.g., using a Chinese model for stock analysis topics, a faster model for crypto trading topics, etc.).