[BUG] Computer use (macOS): Claude window is moved and maximized onto the active display while screen control is running

Preflight Checklist

• [x] I have searched existing issues 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?

Environment

• Claude Desktop (Code tab), macOS 26.6.2 (Build 25G83)
• Claude Code 2.1.215
• Google Ads Editor 14.13.3 as the controlled app
• Three displays:
• "Mi Monitor" 3440x1440 (main display, origin 0,0)
• "RTK UHD" 3200x2400, scaled to 1600x1200 (origin 3440,0)
• Built-in Retina 2880x1864
• Desktop bounds: -1710, 0, 5040, 1440

Summary

While a computer-use turn is running, the Claude window is moved from the
secondary display to the main display and resized to that display's full
size. It returns to its original position and size once control is handed
back to the user. During the turn the user cannot read the conversation,
because the Claude window now sits on the same display Claude is working
on and is covered by the controlled app.

Actual

Measured via AppleScript, before and after one screenshot action:

before: position 3440, 240 size 1600x1200 (secondary display)
after: position 0, 0 size 3440x1440 (main display, full size)

A single screenshot call is enough to trigger it. The window is restored
to its original geometry when control returns to the user, so the effect
is temporary — but it lasts for the entire duration of the turn.

Impact

The user cannot follow what Claude is doing while it is doing it. On a
long turn (in our case several hundred UI actions across ~40 minutes),
the conversation is unreadable throughout, which removes the ability to
notice a wrong action early and interrupt. The window also lands on the
display Claude is operating on, so it is additionally obscured by the
controlled application.

Notes

• Not caused by the app-hiding behaviour: the window is relocated and

resized, not hidden.

• Not configurable: Settings > General offers only "Denied apps" and

"Unhide apps when Claude finishes"; neither affects window geometry.

• Not recoverable from outside during the turn: setting the position via

AppleScript works, but the Claude app ignores external size changes
(AXFullScreen is false, so it is not a fullscreen-mode issue).

Related

• #76532 (Windows, closed as invalid): mentions the window resizing as a

side effect of Computer Use, alongside a focus-lock problem. Suggests the
resize behaviour is not macOS-specific.

• #90361, #71929: Windows z-order / always-on-top issues — different

symptom, listed here only because GitHub flagged them as potential
duplicates.

What Should Happen?

The Claude window should keep the position and size the user assigned to it while screen control is running.

The documentation states that the Claude window "stays visible and is excluded from screenshots" during computer use, which implies it should remain readable — not be relocated onto the display Claude is operating on and expanded to that display's full size.

In a multi-monitor setup users typically place Claude on one display precisely so they can follow the conversation while Claude works on another. The current behaviour defeats that.

Error Messages/Logs

Steps to Reproduce

1. Multi-monitor setup; place the Claude window on a secondary display.
2. Grant computer-use access to an application located on the main display.
3. Trigger a single screenshot action.
4. While the turn is still running, query the window geometry:

osascript -e 'tell application "System Events" to tell process "Claude" to get {position, size} of window 1'

1. Compare against the geometry measured before the turn.
2. Observe that the window returns to its original geometry once control is handed back.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.215

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

This concerns the Claude Desktop app (Code tab) with computer use enabled, not the CLI — hence "Other" under Terminal/Shell. Access is via a Claude Max subscription, not direct API usage; "Anthropic API" was selected under Platform because it is the closest available option (not Bedrock, not Vertex).

The behaviour was observed repeatedly across a long session driving a native macOS application (Google Ads Editor) through several hundred UI actions. It occurs on every turn that uses screen control, including turns that only take a single screenshot.

The geometry values above were captured with AppleScript immediately before and during a turn, so they are measured rather than estimated.