fix(client): "Subagent needs input" no longer sticks after the subagent finishes

[shivamhwp]

Closes #18978

Problem

A subagent can leave an async question pending after its run ends (Codex does this on purpose so the question stays answerable). The parent's "Subagent needs input" pill counted any pending question on a child, so after the subagent finished, the parent kept showing the pill forever, even when it was just waiting on a plain reply from the user.

Fix

The shared childThreadInputsAtom now only counts a subagent's question while that subagent still has a live run (its activityRunStatus is set). A finished subagent stops lighting up the parent. A follow-up queued behind a run that is blocked on a question doesn't hide it. Older servers that don't send activityRunStatus fall back to the latest run's status. The question is still on the subagent's own thread if someone opens it.

This is in packages/client-runtime, so web, desktop and mobile all get it. It's client-only, so it also clears questions that are already stuck in existing databases.

Related: #18459 closes these questions on the server when a Codex task ends. That helps going forward, but questions that are already stuck stay pending. This PR fixes the pill either way.

Evidence

Android, POCO F4, dev client. Test data: a parent Claude thread delegated a tiny task, the subagent finished, and the parent ended with a plain question. A pending async question was left on the finished subagent (what a Codex subagent leaves behind).

Before (main)	After (this PR)
Full video	Full video

Before: the subagent shows Completed, but "Subagent needs input" still shows. After: no pill.

Testing

• vp test run src/state/threadShell.test.ts in packages/client-runtime: new test covers running, queued-behind-a-blocked-run, completed and older-server shells. It fails without the fix, and the queued case fails with a status-only check.
• Lint and typecheck for packages/client-runtime pass.

Fixed with Claude Opus 5.5 in Claude Code, run through T3 Code.

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Approved at f726d1c

Macroscope's review found this PR approvable — The change is a narrowly scoped client-side bug fix that removes a stale “Subagent needs input” indicator while preserving active and queued-question cases. It adds targeted coverage and has no schema, server-processing, product-default, or static-analysis implications.

No code changes detected at afe50db. Prior analysis still applies.

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• packages/client-runtime/src/state/threadShell.test.ts
• packages/client-runtime/src/state/threadShell.ts

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📝 Walkthrough

Child-thread input summaries now include pending user-input requests only when the child run is live and the child is not a provider-native subagent. The live-status check uses activityRunStatus when present and overall status for legacy snapshots.

Changes: Child-thread input summaries

Layer / File(s)	Summary
Live child-run filtering packages/client-runtime/src/state/threadShell.ts, packages/client-runtime/src/state/threadShell.test.ts	The child-input list now filters pending user-input requests by whether the child run is live. Tests cover running and queued children, completed children, and a completed legacy snapshot without activityRunStatus.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Low

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to f726d

The parent badge should clear when a subagent finishes while still appearing for live pending questions. No merge-blocking issue is identified.

### Architecture Summary

Architecture risk: 🟡 Medium · up to f726d

The change affects 1 system.

Changed systems: packages/client-runtime

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

• observed — packages/client-runtime (library) was modified; 2 changed files map to changed impact.

Before / after behavior

• observed — Modified behavior in packages/client-runtime/src/state/threadShell.test.ts: The test adds the RuntimeRequestId import.
• observed — Modified behavior in packages/client-runtime/src/state/threadShell.test.ts: The test adds the v2Now fixture import.
• observed — Modified behavior in packages/client-runtime/src/state/threadShell.test.ts: A test is added for parent child-input aggregation: a running subagent with a pending user-input request is included, remains included when queued, and is excluded when completed. The test also checks exclusion for a completed legacy snapshot without activityRunStatus.
• observed — Modified behavior in packages/client-runtime/src/state/threadShell.ts: Adds isChildRunLive: when activityRunStatus is defined, only a non-null value counts as live; otherwise, the helper checks whether status is preparing, starting, running, or waiting.

Reliability and maintainability

• inferred — Risk-relevant change factors for packages/client-runtime: blast_radius_1; direct_dependents_1

Pre-merge checks: 4

Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check		Issue #18978 requires the “Subagent needs input” badge to appear only while a subagent is waiting. childThreadInputsAtom now requires a pending user_input request and a live child run. It treats a…
Out of Scope Changes check		The pull request changes only the client-runtime child-input filter and its focused test. The live-run filter directly addresses issue #18978. The test supports that behavior and no unrelated change i…
Title check		The title clearly and concisely describes the main fix: preventing the “Subagent needs input” indicator from remaining after a subagent finishes.
Description check		The description explains the problem, expected behavior, implementation, scope, linked issues, evidence, focused tests, lint, typecheck, and manual verification. It uses “Fix” and “Testing” headings i…

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