common : add parser for ministral/mistral large 3

[aldehir]

Parser implementation for Ministral 3 Reasoning/Instruct and Mistral Large 3 Instruct. It deviates from the current Mistral implementation by accepting tool calls in the form: [TOOL_CALLS]tool_name[ARGS]{"arg1": ... }...

Features

• Extracts reasoning to reasoning_content when reasoning_format = auto/deepseek. If reasoning_format = none, the traces are left in content.
• Formats system and assistant messages containing reasoning_content into {"type": "thinking", "thinking": "..."} content blocks the chat template expects. server: thinking type rejected as invalid but used by Ministral 3 #17700
• Supports tool calling for both tool_choice = auto and tool_choice = required (with thinking).
• Supports parallel tool calls
• Supports response_format with thinking.

Additional Changes

• Exposed reasoning_format during chat param init to build the appropriate parser.
• Added make_peg_parser helper in tests/test-chat.cpp for use with peg parsers.
• Included the Unsloth template. Minja does not detect tool calling capabilities with the official template because of an exception it raises.

[aldehir]

@pwilkin don't worry, I'm still leaving Qwen3-Coder for you. I added some testing logic since you had ideas about how we should test.

[pwilkin]

Any chance you could make those test cases into universal test cases for a testcase class / lambda where the only parameters for the actual test case are the parser and the expected string? So that the test case invocations look like:

test_hello_world(&p, "Hello world");
...
test_tool_with_reasoning(&p, "{iamthinking}Thinking of calling tool get_weather{iamnotthinking}{iamcallingatool}get_weather{withparameter}place{ofvalue}Paris{imdonecallingatool}");

?

[aldehir]

I get where you're coming from. I'll play around with it. Another option is table driven tests. They work well at reducing duplication when you have many similar looking tests.

One thing I don't like about some of the helpers at the top is that I have scroll up to find the actual content it compares against.

[pwilkin]

One thing I don't like about some of the helpers at the top is that I have scroll up to find the actual content it compares against.

I think a decent idea to combat that is to have a comment that keeps a template of all the tests with placeholders - then when you implement the model, you just move the comment to after the new model :)