Fix GLM 5.2 image support flag for screenshot tool compatibility

[exedev-shelley]

Author: philz42
Channel: #shelley
Link: https://discord.com/channels/1405685085923049482/1450334528210993295/1518983973588566208

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Issue

The screenshot tool is producing sporadic errors when used with GLM 5.2. The root cause appears to be that GLM 5.2 does not support image attachments, but the read_image capability flag may not be set correctly or is not being properly piped through to the screenshot tool.

Context

GLM 5.2 lacks vision/image attachment support, so when the screenshot tool sends an image to the model, it cannot process it. However, the tool doesn't error consistently—only sporadically—suggesting the capability flag is either:

1. Not set correctly for GLM 5.2
2. Not being properly communicated to the screenshot tool

Shelley has logic to disable read_image for models that don't support images, but this may need to be verified/fixed for GLM 5.2.

Action Items

• Verify GLM 5.2's image support capability flag in Shelley
• Ensure the flag is correctly set (disabled for GLM 5.2)
• Confirm the flag is properly piped through to the screenshot tool
• Test to ensure screenshot tool errors consistently (or handles gracefully) when image support is disabled