[BUG] Cowork in-session task list (Progress widget) does not repaint rows after TaskUpdate marks them completed

What happened

In a Cowork session, tasks set to completed via the TaskUpdate tool keep rendering as incomplete (grey numbered circle, no strikethrough) in the in-session Progress task-list widget. TaskGet confirms Status: completed for the same tasks, so the task store is correct — only the widget view is stale.

Environment

• Claude Desktop: 1.11847.5 (9692f0), build 2026-06-09T17:34:27Z
• macOS: 26.5.1 (25F80)
• Chip: Apple M4 Pro (Apple silicon)
• Install / update channel: iru
• Surface: Claude Desktop → Cowork mode
• Model: claude-opus-4-8 (1M context)
• Session: project-scoped, long-running; ~11 in-session tasks
• Cowork Linux sandbox (where shell/code runs; likely not where the bug is): Ubuntu 22.04.5 LTS, kernel 6.8.0-124-generic, aarch64 (ARM64), Node v22.22.3, Python 3.10.12

Steps to reproduce

1. Create ~11 tasks in a Cowork session.
2. Mark several completed via TaskUpdate partway through (here: task #5 "Compile verification findings report" and task #10 "Verify estimate math and assumptions").
3. Run TaskGet on those IDs → returns Status: completed.
4. Observe the Progress widget.

Expected

Rows reflect the current task store after TaskUpdate (checkmark + strikethrough).

Actual

• The two completed rows continue showing as open across multiple turns.
• Repeated TaskUpdate calls return success but do not refresh the rows.
• Separately, a different task's row showed a stale label (old subject text) after its subject/description were updated, while its checkmark did update — suggesting partial/selective row re-rendering.

Workaround

None known. The stale rows never self-corrected — not on Progress-panel collapse/expand, not across many subsequent turns, not after repeated successful TaskUpdate calls. The completed rows stayed rendered as open for the rest of the session. (An earlier draft of this report suggested collapse/expand forced a refresh; that was premature — it does not.)

Notes

• Source of truth (TaskGet) was correct throughout; this is a view-layer sync issue, not data loss.
• Reproducible and persistent within the session.
• Possibly related (different surface — scheduled tasks): #63146, #60553.