codex - 💡(How to fix) Fix [Bug] Custom Codex pets render as a vertical line or disappear on Windows with Thunderbolt dock / external monitors [1 comments, 1 participants]

What version of the Codex App are you using?

Codex Desktop App on Windows:

• App package: OpenAI.Codex_26.506.3741.0_x64__2p2nqsd0c76g0
• Product version shown by process metadata: 26.506.31421
• Bundled codex.exe: 0.130.0-alpha.5

What platform is your computer?

• Windows: Microsoft Windows NT 10.0.26200.0
• Architecture: x64
• GPUs detected:
  • NVIDIA GeForce RTX 3080, driver 32.0.15.9186, external mode observed: 3440 x 1440
  • Intel(R) Arc(TM) Graphics, driver 32.0.101.6913, internal mode observed: 2880 x 1800
• Laptop is connected through a Thunderbolt cable to a docking station with external monitors.

What issue are you seeing?

Custom Codex pets do not render correctly when the laptop is attached to a Thunderbolt docking station with external monitors.

Observed behavior:

• On the laptop without the dock, the custom pet has fewer rendering problems.
• With the Thunderbolt dock connected, the pet is often rendered as only a single vertical line, only a partial slice, or not visible at all.
• The thinking/status bubble still renders, for example Create personalized pet / Denke nach, but the pet sprite itself is missing or appears as a thin line.
• The issue is not limited to the thinking state; it affects the pet generally.
• The problem persists across multiple valid custom pet packages.

Expected behavior:

• Custom pets should render the currently selected atlas frame normally in the Codex UI regardless of docking station, external monitor, GPU, or DPI scaling.

What steps can reproduce the bug?

1. Install one or more custom pets under %USERPROFILE%\.codex\pets\.
2. Use a valid custom pet package with:
   • pet.json
   • spritesheet.webp
   • atlas dimensions 1536x1872
   • 8 x 9 grid
   • 192x208 cells
3. Start Codex Desktop while the laptop is not attached to the dock.
4. Select the custom pet and observe rendering.
5. Attach the laptop to a Thunderbolt docking station with external monitors.
6. Restart Codex Desktop and select the same custom pet.
7. Trigger any state, including thinking/status bubble rendering.

Actual result:

• The bubble renders, but the pet sprite is absent or appears as a single thin vertical line.

Expected result:

• The pet sprite should render as a normal animated sprite.

Repro assets tested

Three separate custom pet packages were tested:

• axiom-orbit
• axiom-orbit-fresh
• render-test

render-test is a minimal diagnostic custom pet with transparent cells and high-contrast color-band markers. It validates successfully and is intended to make slicing/cropping obvious.

All tested atlases validate as:

• Format: WEBP
• Mode: RGBA
• Dimensions: 1536x1872
• No validation errors from the hatch-pet atlas validator.

Troubleshooting already attempted

• Repackaged the pet as WebP and PNG.
• Changed pet.json to point to PNG; PNG made the pet not visible, so reverted to WebP.
• Built several geometry variants:
  • full/app-fit centered bounds
  • smaller dock-safe top-half bounds
  • left-third-safe bounds
• Created a new pet ID (axiom-orbit-fresh) to bypass possible asset cache.
• Created a diagnostic render-test pet to rule out detailed artwork as the cause.
• Restarted/reselected pets during testing.

None of the variants fixed the dock rendering behavior.

Screenshots / repro assets

Screenshots are available showing the status/thinking bubble visible while the pet itself is missing or reduced to a line. A small repro package with the tested custom pet folders is also available if maintainers want it.

Notes

The behavior looks like a renderer/DPI/GPU issue in custom pet sprite drawing rather than an invalid atlas:

• The Codex UI/bubble continues rendering.
• The custom pet sprite layer appears clipped to a line or disappears.
• Multiple valid atlases and a minimal diagnostic pet reproduce the issue.
• The issue correlates with Thunderbolt dock / external monitor use.