ADR 0202: Expose Effective Subagent Thinking Metadata

• Status: Accepted
• Date: 2026-09-09
• Decision: D369
• Related: ADR 0062, ADR 0089, ADR 0144, ADR 0194

Context

Delegation cards already receive the provider/model selected for each Task run, but they do not receive the thinking level that the runtime actually passed to that delegate. The selected level can differ from the definition or parent setting after inheritance and target-model capability clamping. Making the renderer infer it would make live, restored, and parallel delegations inconsistent.

Decision

• Resolve the delegate's effective thinking selection once, immediately before constructing SubagentRun, using the same provider binding and clamping path that controls the request.
• Include modelId and thinkingLevel in the immediate Task result, the SubagentRunResult, and lifecycle snapshots (TaskWait, TaskList, and TaskStop). omit remains an explicit no-provider-override value.
• Render the result's model and a localized thinking label together on each delegation node and in the side-dock identity header. Omit the label for off, omit, or any unrecognized value; never derive a replacement from the parent session or subagent definition.

This is additive to the existing delegation result details. It changes no host protocol, storage schema, provider request, or delegation lifecycle behavior.

Consequences

Live and restored cards have one runtime-owned source of truth, and parallel delegates can show different effective levels without cross-talk. The UI can keep narrow layouts bounded while exposing the complete combined label through the accessible name and hover title. A provider default selected by omit is intentionally not represented as a concrete visible level because the runtime does not know that adapter-owned default as a canonical thinking value.

Verification

Runtime tests cover result metadata and capability clamping; renderer source contracts cover both the topology node and side-dock header, including the off/omit suppression rule. E2E-219 records the live, narrow-layout, and history-restoration journey.