#20712: fix(subagents): prioritize agent runtime default model over global defaults on spawn

## Summary Fix subagent model resolution so `sessions_spawn` prefers the target agent’s runtime default model before falling back to `agents.defaults.model.primary`. ## Root Cause `resolveSubagentSpawnModelSelect ion` used this order: 1. explicit `sessions_spawn.model` 2. subagent model config (`subagents.model` / per-agent subagents / agent model) 3. `agents.defaults.model.primary` 4. runtime default from `resolveDefaultModelForAgent` Because global `agents.defaults.model.primary` was checked before runtime default, agent-specific runtime defaults could be incorrectly overridden during subagent spawn. ## Fix Updated `resolveSubagentSpawnModelSelect ion` in `src/agents/model-selection.ts`: - removed the direct fallback to `agents.defaults.model.primary` - now falls back directly to runtime default (`resolveDefaultModelForAgent`), which already resolves agent-specific primary model correctly Effective precedence is now: 1. explicit `sessions_spawn.model` 2. subagent-specific configured model 3. target agent runtime default model ## Test Plan Ran: ```bash corepack pnpm vitest run --config vitest.e2e.config.ts src/agents/openclaw-tools.subagents.sessions-spawn.model.e2e.test.ts ``` Result: - 1 test file passed - 9 tests passed Includes the repro scenario: - target agent has custom primary model - spawn called without model override - expected: child session uses agent model, not global defaults primary Backward Compatibility - No API/schema changes - Explicit sessions_spawn.model behavior unchanged - Existing subagent-specific model configs remain highest-priority after explicit override - Only fallback precedence is corrected to match intended behavior Fixes #20002 <!-- greptile_comment --> <h3>Greptile Summary</h3> Fixed subagent model resolution to correctly prioritize agent-specific runtime default models over global `agents.defaults.model.primary`. The change removes a premature fallback to the global default, allowing `resolveDefaultModelForAgent` to properly apply agent-specific model configuration before falling back to global defaults. This ensures that when spawning a subagent for an agent with a custom primary model, the agent's model is used instead of being incorrectly overridden by the global default. **Key changes:** - Removed direct fallback to `agents.defaults.model.primary` in `resolveSubagentSpawnModelSelection` (src/agents/model-selection.ts:346) - Updated test description to clarify the expected behavior - All existing tests pass, including the new test validating the fix <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk - The fix is a simple one-line removal that corrects the model resolution precedence order. The logic is sound: `resolveDefaultModelForAgent` already handles agent-specific model overrides correctly by temporarily patching the config before calling `resolveConfiguredModelRef`. The removed line was causing premature fallback to global defaults, bypassing agent-specific configuration. All tests pass, including a specific test validating the corrected behavior. No API or schema changes, backward compatible. - No files require special attention _{Last reviewed commit: f19023d} <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->