feat: make task subagent model selection the default

[marius-kilocode]

What Problem This Solves

Task subagent model selection was gated behind the experimental.task_model_selection flag, off by default. Users who wanted to request a specific model, provider, or reasoning effort for a single subagent task had to discover and enable an experiment first.

Why This Change Was Made

The feature is stable, and its explicit-request-only behavior already prevents the agent from switching models autonomously. The flag no longer adds safety, so it is removed and the capability becomes the default everywhere. The change also deletes a config key, a settings toggle, and the related locale strings.

User Impact

• Task subagent model selection is always available. There is no experiment toggle and no experimental.task_model_selection config key.
• The agent_manager_models tool is now offered to all clients, including CLI, JetBrains, and desktop, instead of only VS Code and opted-in CLI sessions.
• The VS Code Experimental tab no longer shows the Task Subagent Model Selection switch.
• Docs describe per-task selection without the experimental framing.

Evidence

• bun test ./test/kilocode/tool-task-model.test.ts (44 pass)
• bun test ./test/kilocode/agent-manager-models-tool.test.ts ./test/kilocode/tool-registry-indexing.test.ts ./test/kilocode/chart-tool-gating.test.ts (28 pass)
• bun test ./test/kilocode/server/config-overlay.test.ts (37 pass)
• bun test ./test/tool/parameters.test.ts (61 pass)
• bun run typecheck in packages/opencode and packages/kilo-vscode
• bun run test:unit in packages/kilo-vscode (6379 pass, 0 fail)
• bun run lint (0 errors), knip, check-kilocode-change, and the opencode annotation check pass
• SDK and OpenAPI regenerated with ./script/generate.ts

No cloud change is required: the cloud config schema does not reference task_model_selection.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Verified the flag removal in KiloTask.resolveModel, the unconditional agent_manager_models registration, the config/SDK schema deletions, the docs anchor updates, and the test rewrites. No stale references to task_model_selection remain outside the changeset, and the Tool.define init refactor (object instead of factory) matches the Init union type. No new issues found on changed lines.

Files Reviewed (39 files)

• .changeset/task-model-selection-default.md
• packages/core/src/v1/config/config.ts
• packages/kilo-docs/pages/code-with-ai/agents/context-mentions.md
• packages/kilo-docs/pages/code-with-ai/agents/model-selection.md
• packages/kilo-docs/pages/getting-started/settings/index.md
• packages/kilo-vscode/tests/unit/task-model-selection.test.ts
• packages/kilo-vscode/webview-ui/src/components/settings/ExperimentalTab.tsx
• packages/kilo-vscode/webview-ui/src/i18n/*.ts (21 locales)
• packages/kilo-vscode/webview-ui/src/types/messages/config.ts
• packages/opencode/src/kilocode/tool/agent-manager-models.ts
• packages/opencode/src/kilocode/tool/registry.ts
• packages/opencode/src/kilocode/tool/task.ts
• packages/opencode/src/tool/task.ts
• packages/opencode/test/kilocode/agent-manager-models-tool.test.ts
• packages/opencode/test/kilocode/server/config-overlay.test.ts
• packages/opencode/test/kilocode/tool-registry-indexing.test.ts
• packages/opencode/test/kilocode/tool-task-model.test.ts
• packages/sdk/js/src/v2/gen/types.gen.ts
• packages/sdk/openapi.json

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_{Reviewed by deepseek-v4.1-flash · Input: 0 · Output: 0 · Cached: 0}

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