[BUG] Cowork (Windows): scheduled task with a folder + "Require this computer" won't save when the model is Haiku 4.5 — toast blames the folder name

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) and this hasn't been reported yet
- [x] This is a single bug report (please file separate reports for different bugs)
- [x] I am using the latest version of Claude Code

### What's Wrong?

In Claude Desktop (Cowork) on Windows, the **New / Edit scheduled task** dialog refuses to save a task that has a folder attached and **Require this computer** enabled whenever the selected model is **Claude Haiku 4.5**. The toast attributes the failure to the folder's name:

> One of this task's folders has a name that can't be saved for a task that requires a computer (quotes, angle brackets, or other special characters), so your changes weren't saved. Rename the folder or remove it, then try again.

The folder name is not the cause. The identical task, folder and toggle save immediately with the **default model** or **Sonnet**, and switching a saved task back to Haiku 4.5 reproduces the toast. The misleading message cost about two hours of folder renames and path changes before the model was tried.

**Environment**
- Claude Desktop **1.52386.6** (Cowork), Windows 11
- Team plan; org setting *Require trusted devices* = OFF
- Task type: cloud scheduled task bound to this computer (`created_via: http_api`; readback `derived_state.folders_state: FOLDERS_STATE_PRESENT` once saved)
- Observed 2026-09-14, 16:20–17:10 CDT

**Steps to reproduce**
1. Scheduled tasks → **New scheduled task**; any name and instructions.
2. Attach one folder, e.g. `C:\Users\\Documents\Verse_of_the_Day` (plain ASCII — letters, underscores, backslashes, colon; no quotes, angle brackets, ampersands or spaces).
3. Permissions: **Automatically approve**. Toggle **Require this computer** ON.
4. Model picker: **Haiku 4.5**. Click **Save** → the toast above; nothing is saved.
5. Change only the model to **Sonnet** (or leave the default) → Save succeeds and the task is bound (`list_triggers` shows `FOLDERS_STATE_PRESENT`, the folder path, `permission_mode: auto`, `model: claude-sonnet-5`).
6. Edit the saved task, set the model back to **Haiku 4.5**, Save → the same folder-name toast.

**Evidence the folder name is not the trigger** — the toast appeared for all of these, on an agent-created task and on a brand-new one, as long as the model was Haiku 4.5:
- `G:\Users\\OneDrive - Texas A&M University\Documents TAMU\A&M Engineer\To Sort\Verse of the Day`
- `C:\Users\\Documents\Verse of The Day`
- `C:\Users\\Documents\Verse_of_the_Day`

The last path contains no character the message names. The same dialog saved the same folder the moment the model was anything other than Haiku 4.5.

**Impact**
- The cheapest model can't be used for small device-bound tasks (this one appends one line to a Markdown file three times a day).
- The error text points at the wrong component, so the natural fixes (rename the folder, move it out of OneDrive, remove `&` from the path) all fail; the real fix is found only by accident.

**Related:** #92268 (agent-created scheduled tasks can't be device-bound / "Require this computer" on the Edit dialog).

**Workaround:** Sonnet or Opus for any task that requires the computer; Haiku 4.5 for cloud-only tasks.

### What Should Happen?

Either Haiku 4.5 is accepted for device-bound tasks like the other models, or — if it is intentionally unsupported for tasks that require the computer — the model picker disables it (or the toast says "Haiku 4.5 can't be used for a task that requires this computer — choose another model") instead of sending the user off to rename folders.

### Error Messages/Logs

```shell
Toast on Save (verbatim):
One of this task's folders has a name that can't be saved for a task that requires a computer (quotes, angle brackets, or other special characters), so your changes weren't saved. Rename the folder or remove it, then try again.

Readback after the same task saved on Sonnet (list_triggers):
created_via: http_api
derived_state.folders_state: FOLDERS_STATE_PRESENT
derived_state.folders: ["C:\\Users\\\\Documents\\E"]
derived_state.permission_mode: auto
derived_state.model: claude-sonnet-5

App: Claude Desktop 1.52386.6 (Windows 11), Cowork scheduled tasks.
```

### Steps to Reproduce

1. Claude Desktop (Cowork) on Windows → Scheduled tasks → **New scheduled task**. Any name and instructions.
2. Attach one folder, e.g. `C:\Users\\Documents\Example` (plain ASCII, no quotes / angle brackets / ampersands / spaces).
3. Permissions **Automatically approve**; toggle **Require this computer** ON.
4. Model picker **Haiku 4.5** → **Save**.
Result: toast "One of this task's folders has a name that can't be saved for a task that requires a computer…"; nothing saved.
5. Change only the model to **Sonnet** (or the default) → **Save**.
Result: saves and binds (`list_triggers` readback: `FOLDERS_STATE_PRESENT`, `permission_mode: auto`, `model: claude-sonnet-5`).
6. Edit the saved task, set model back to **Haiku 4.5** → **Save** → the same toast again.

### Claude Model

Other

### Is this a regression?

I don't know

### Last Working Version

_No response_

### Claude Code Version

Claude Desktop 1.52386.6 (Cowork, Windows) — bundled Claude Code CLI 2.1.270

### Platform

Other

### Operating System

Windows

### Terminal/Shell

Other

### Additional Information

This is a **Claude Desktop (Cowork) scheduled-task dialog** bug, not a CLI bug — the form's Platform / Terminal fields don't fit, so they are set to Other. Plan: Team (claude.ai). Screenshots of the toast are available on request. Reporter: Jonathan Snodgrass