fix(sessions): keep subagent progress live without navigation

[reachjalil]

Problem

A running sub-agent can stop showing fresh activity in its parent thread until the user opens the child chat. The child transcript has no query observer while only the parent is visible, so normal cache garbage collection can remove the baseline needed to apply subsequent progress deltas.

Change

• Retain one disabled transcript query observer while a session is both active and tracked.
• Share retention across tracking owners and release it on terminal status, tracking cleanup, or workspace disposal.
• Preserve normal transcript garbage collection; add no polling or automatic history requests.
• Add seven regression cases covering navigation-free text/reasoning updates beyond the GC threshold, parent progress derivation, ownership, and cleanup.

Existing labels and layout are unchanged. This is a synchronization-only fix.

Validation

• Red/green: both navigation-free child progress cases failed before the fix because the baseline was collected; all seven retention cases pass after the fix.
• Focused session sync, lifecycle, permissions, tool parts, cache GC, and sub-agent rendering tests: 223 passed, 0 failed across seven files.
• App typecheck: passed.
• git diff --check: passed.
• Independent code review: no blockers.

Scope and limitations

No running-app or desktop E2E was performed. Tests exercise real sync-event handling, TanStack GC, and parent progress derivation, with child tracking already established. This addresses active transcript eviction; missed initial child discovery and reconnect-history recovery are not changed.

[vercel]

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Project	Deployment	Actions	Updated
openwork-app	Ready	Preview	Sep 18, 2026 5:52pm UTC

3 Skipped Deployments

Project	Deployment	Actions	Updated
openwork-den	Skipped		Sep 18, 2026 5:52pm UTC
openwork-diagnostics	Skipped		Sep 18, 2026 5:52pm UTC
openwork-landing	Skipped		Sep 18, 2026 5:52pm UTC

[github-actions]

Selected evidence: Incomplete · 12/12 tests · 18/18 assertions · 8 images

Commit 5cc39f154a9ffe5e52e83a0246f18421748fa6bc · selected evidence
Required verification is reported separately by the current-head Required verification check.

Open review report

Coverage gaps: Required verification: incomplete. Selected evidence does not satisfy all required specs. No authenticated current-head required plan is available.