feat: support subagent reasoning overrides

[marius-kilocode]

The global subagent model setting previously coupled reasoning effort to a single legacy variant value, which could become invalid when models changed and could not safely account for custom subagents using different models.

This adds model-specific subagent variant overrides while keeping the settings UI focused on one model and one matching reasoning selector. The general subagent receives the selected model and reasoning effort, while custom subagents retain their own model and only receive an override when one exists and is valid for that exact model. Stale or incompatible variants fall back to the agent's resolved variant instead of crossing model boundaries.

The settings controls also constrain long model labels to their input column so names truncate rather than overlap adjacent content.

[kilo-code-bot]

WARNING: getModel is called here without a ProviderModelNotFoundError handler, unlike the adjacent non-direct path (lines 153–164) and the parent fallback path (lines 177–179).

If an agent has model hard-coded in its config and the provider later removes or renames that model, and the user has set a subagent_variant_override for it, this call will propagate an unhandled ProviderModelNotFoundError rather than gracefully falling back to choice.variant.

The fix mirrors the parent fallback:

const full = yield* input.provider
  .getModel(choice.model.providerID, choice.model.modelID)
  .pipe(Effect.catchTag("ProviderModelNotFoundError", () => Effect.succeed(undefined)))
const variant = full?.variants?.[value] ? value : choice.variant
return { model: choice.model, variant }

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_{Reply with @kilocode-bot fix it to have Kilo Code address this issue.}

[kilo-code-bot]

Code Review Summary

Status: 2 Issues Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	1
SUGGESTION	1

Issue Details (click to expand)

WARNING

File	Line	Issue
packages/opencode/src/kilocode/tool/task.ts	149	getModel called without ProviderModelNotFoundError handler in the direct branch when an override is present — unhandled error if model is missing

SUGGESTION

File	Line	Issue
packages/sdk/js/src/v2/gen/types.gen.ts	1335	SDK type { [key: string]: string } omits null values allowed by Config.Info and the webview Config type — no delete-sentinel support in the SDK contract

Other Observations (not in diff)

SDK type narrower than runtime: packages/sdk/js/src/v2/gen/types.gen.ts:1335-1337 declares subagent_variant_overrides as { [key: string]: string }. The authoritative schema in packages/opencode/src/config/config.ts and the webview type in packages/kilo-vscode/webview-ui/src/types/messages/config.ts both allow string | null values (nulls act as delete sentinels for individual model entries). The generated SDK type is derived from packages/sdk/openapi.json which only has "type": "string" for the additional-properties value — it has no null there either. This is a generated artifact drift: the openapi.json and SDK type don't represent the null-sentinel protocol the backend actually accepts. As a result, any SDK consumer that inspects the type contract would not know to send null to clear a single model entry. Consider either adding nullable: true to the additionalProperties in openapi.json/config schema, or documenting this as intentional (that nulls are an internal merge protocol not surfaced via the public API).

No test for direct-path model missing + override: The test suite covers stale variants on the direct path ("stale model-specific override preserves the resolved variant"), but not the case where the agent's hard-coded model is missing from the provider and an override is set — the unhandled error path flagged inline would not be caught by existing tests.

Files Reviewed (8 files)

• packages/opencode/src/kilocode/tool/task.ts — 1 issue
• packages/opencode/src/config/config.ts
• packages/opencode/test/kilocode/tool-task-model.test.ts
• packages/opencode/test/kilocode/config/config.test.ts
• packages/kilo-vscode/webview-ui/src/components/settings/ModelsTab.tsx
• packages/kilo-vscode/webview-ui/src/types/messages/config.ts
• packages/sdk/js/src/v2/gen/types.gen.ts — 1 observation
• packages/kilo-vscode/tests/unit/settings-io.test.ts
• .changeset/bright-subagents-reason.md

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_{Reviewed by claude-4.6-sonnet-20260217 · 1,568,548 tokens}

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