fix(cli): inherit reasoning in task subagents

[marius-kilocode]

Task-tool subagents that fall back to the calling model currently preserve its provider and model ID but discard the selected variant. This causes delegated work to silently lose the parent's reasoning effort even though it is using the same model.

Preserve the parent variant only when model resolution reaches the true parent-model fallback. Saved selections, per-agent models, and the global subagent model continue to use their own independently resolved variants, so model-specific reasoning settings are not carried across incompatible overrides.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

The fix is well-scoped and correct. The variant is threaded through only to the parent-model fallback path, so saved selections, per-agent pinned models, and configured subagent models all continue resolving their own variants independently. Test coverage is thorough — all pre-existing toBeUndefined() expectations remain valid because those tests either resolve a non-fallback path (saved/config model found, so input.variant is never returned) or don't pass a parent variant at all.

Files Reviewed (3 files)

• .changeset/brave-subagents-think.md
• packages/opencode/src/kilocode/tool/task.ts
• packages/opencode/src/tool/task.ts
• packages/opencode/test/kilocode/tool-task-model.test.ts

---

_{Reviewed by claude-4.6-sonnet-20260217 · 834,222 tokens}

_{Review guidance: REVIEW.md from base branch main}