[BUG] Scheduled tasks: clicking "Run now" silently does nothing (no run session, no lastRunAt, no error)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

Environment

• App: Claude desktop app for macOS, version 1.20186.1
• OS: macOS 27.0 (build 26A5378j)
• Feature affected: Claude Code local scheduled tasks (Scheduled sidebar section)

What's Wrong?

Clicking "Run now" on a local scheduled task in the Scheduled sidebar section silently does nothing. The button is present and clickable (not grayed out), but after clicking:

• No run session is created (normally every task run creates a session titled after the task id — verified against the run history of other tasks on the same machine).
• lastRunAt is never stamped (verified via the scheduled-tasks MCP list_scheduled_tasks immediately after clicking, and again several minutes later).
• No error, toast, or any other feedback is shown.

Reproduced twice, several minutes apart, on a one-time future-dated task (fireAt ~5 days out, enabled: true).

Meanwhile, scheduled firings work fine on this machine — cron and fireAt tasks run on time and each creates its run session and stamps lastRunAt. Only the manual trigger is dead.

Steps to Reproduce

1. Create a one-time scheduled task with a fireAt several days in the future (e.g. via the scheduled-tasks MCP create_scheduled_task).
2. Open the Scheduled section in the desktop app sidebar.
3. Click "Run now" on the task.
4. Observe: no new session appears, list_scheduled_tasks shows no lastRunAt, no error or toast.

What Should Happen?

The manual run should start immediately — creating a run session and stamping lastRunAt — regardless of the task's future fireAt.

Why This Matters

The create_scheduled_task tool result itself recommends this exact flow: "If this task is likely to use remote connectors or browser control, recommend the user click 'Run now' first to pre-approve the tools it needs — this prevents future runs from pausing on permission prompts." With the button broken, there is no way to pre-bank tool approvals for a future-dated run. (Workaround used: manually adding permissions.allow rules to project settings.)

Ruled Out / Related Issues

• Not #60580 (CRLF frontmatter graying out the button): the task's SKILL.md is LF-only with valid frontmatter, and the button is not grayed out.
• Not #61456 (sidebar section and button removed): both the Scheduled section and the "Run now" button are present in this build — the button just has no effect.
• #54256 concerns remote routines / RemoteTrigger; this report is about local scheduled tasks.