fix(write): handle array content from GLM and Qwen models

[georgeglarson]

Problem

Some models (GLM 4.6, Qwen 3 Coder 480B) send the write tool's content parameter as an array of strings instead of a single string, causing validation errors:

The write tool was called with invalid arguments:
"Invalid input: expected string, received array"

Solution

This PR adds a custom UnmarshalJSON method to WriteParams that:

• ✅ Accepts string content (existing behavior, fully backward compatible)
• ✅ Accepts array of strings (joins with newlines)
• ✅ Provides clear error messages for invalid types

The fix is transparent to models that send strings and enables compatibility with models that send arrays.

Affected Models

• GLM 4.6
• Qwen 3 Coder 480B
• Any other models that send array content

Testing

Tested with Venice.ai models via VeniceCode (Venice.ai-optimized fork of Crush).

Code Changes

Adds 35 lines to internal/agent/tools/write.go:

• Custom UnmarshalJSON method for WriteParams
• Handles both string and array formats
• Zero breaking changes

Related

• User report: Community feedback on GLM/Qwen compatibility
• VeniceCode: https://github.com/georgeglarson/venicecode

[charmcli]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

[Copilot]

Pull request overview

This PR adds backward-compatible JSON unmarshaling support to handle both string and array-of-strings for the content parameter in the write tool, enabling compatibility with GLM 4.6 and Qwen 3 Coder 480B models that send content as arrays instead of strings.

Key changes:

• Custom UnmarshalJSON method for WriteParams that accepts both string and array formats
• Array elements are joined with newlines to form the final content string
• Added encoding/json import to support custom unmarshaling

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[georgeglarson]

I have read the Contributor License Agreement (CLA) and hereby sign the CLA.

[georgeglarson]

I have read the Contributor License Agreement (CLA) and hereby sign the CLA.

recheck

[georgeglarson]

I have read the Contributor License Agreement (CLA) and hereby sign the CLA.

[georgeglarson]

I have read the Contributor License Agreement (CLA) and hereby sign the CLA. recheck

[georgeglarson]

Closing — CLAAssistant has been failing despite multiple sign attempts over the past ~178 days, with no maintainer engagement to unstick it. Happy to re-open if the upstream CLA flow becomes responsive.