[BUG] Scheduled tasks fire on cron but are not visible in Desktop UI (1.5354.0, Windows)

Summary

After this morning's auto-update, the Claude Desktop UI no longer shows scheduled tasks. The tasks are still firing correctly on their cron schedules — only the UI listing is broken. No known workaround.

Environment

• OS: Windows 11 Pro for Workstations (10.0.26200.8246)
• Claude Desktop app: app-1.5354.0 (auto-installed 2026-04-29 ~10:19 local time)
• Previous Desktop versions on disk where the UI listing was working: app-1.4758.0 and earlier (app-1.3109.0)
• Embedded claude-code CLI version reported in session logs: 2.1.121

What's Wrong

• The Scheduled Tasks UI in the Desktop app is empty / does not list the user's scheduled tasks.
• This persists across app restarts.

What's Still Working (so the data is intact)

• The MCP management server is fine — mcp__scheduled-tasks__list_scheduled_tasks returns the full list of 13 tasks with correct enabled, cronExpression, nextRunAt, lastRunAt, and path.
• The cron scheduler is firing tasks on time. Verified for sf-fixer (cron 33 * * * *):
• Active scheduled run launched at 2026-04-29T08:35:04Z (the session jsonl exists at ~/.claude/projects/F--Dropbox-Dev---Salesforce--claude-worktrees-trusting-bouman-b7445e/8a0b60a9-...jsonl, version 2.1.121).
• Run is mid-flight: overseer + selector completed, 5 fixer sub-agents dispatched in parallel, one returned with a plan; orchestrator waiting on the others.
• Hourly commits to the repo over the last 12+ hours confirm sf-fixer, sf-repo-health, sf-security-audit, sf-triage, sf-release-manager all firing on schedule.
• ~/.claude/scheduled-tasks/<id>/SKILL.md files are intact with valid frontmatter.

Reproduce

1. Have one or more existing scheduled tasks set up under ~/.claude/scheduled-tasks/<id>/.
2. Update Desktop app to 1.5354.0 (auto-update or manual).
3. Open the Scheduled Tasks UI in the Desktop app.
4. Observe: list is empty / the user's tasks are not shown.
5. Confirm the underlying data is intact:

• mcp__scheduled-tasks__list_scheduled_tasks returns the tasks correctly
• ~/.claude/scheduled-tasks/<id>/SKILL.md files exist with valid frontmatter
• Cron is still firing tasks (check lastRunAt timestamps, project session logs, repo commits produced by tasks)

Expected

The Desktop UI should list the same scheduled tasks that mcp__scheduled-tasks__list_scheduled_tasks returns — both should be reading the same source of truth.

Workaround

None known. Tasks continue to run, but the UI is unusable for inspecting/enabling/disabling/editing them. Users can still manage tasks via the MCP server (mcp__scheduled-tasks__* tools) from inside a Claude Code session, but that's an indirect workflow not a UI fix.

Notes

I previously filed #54605 on a wrong premise (assumed scheduled tasks were supposed to surface in the in-session available-skills list — they were not). Closing that and filing this clean report against the actual symptom: the Desktop UI panel itself shows nothing.