fix(adapters/deepseek): enable tool capabilities for reasoner model and handle reasoning_content

[nabiu256]

Description

Fixes two issues in the DeepSeek adapter:

1. Enables tool capabilities for DeepSeek Reasoner model: The DeepSeek Reasoner model (deepseek-reasoner) supports function calling/tools but was incorrectly configured with can_use_tools = false.

2. Adds proper handling of reasoning_content field: DeepSeek's API expects a non-standard reasoning_content field for reasoning models instead of the standard reasoning field used by other providers. This change:

   • Converts reasoning table/string to reasoning_content
   • Ensures reasoning_content exists for assistant messages in reasoning mode
   • Maintains compatibility with existing CodeCompanion reasoning interface

AI Usage

Used opencode to implement the changes based on DeepSeek API documentation and existing adapter patterns.

Testing

• Run make test_file FILE=tests/adapters/http/test_deepseek.lua
• All deepseek adapter tests pass

Checklist

• I've read the contributing guidelines
• I've verified the deepseek adapter tests pass
• (optional) Existing test coverage is sufficient
• (optional) No documentation updates needed for this bug fix

[olimorris]

Thanks for the PR.

but was incorrectly configured with can_use_tools = false.

FYI, this was added when the reasoning models did not support tool calling

Before I can merge this I'll need test coverage of the reasoning output, as we have for the other adapters.

[nabiu256]

FYI, this was added when the reasoning models did not support tool calling
Yes sorry, I didn't mean it was originally wrong but that since DeepSeek Reasoner recently got tools capabilities it needed to be changed.

I'll get on testing asap. Thank you for the quick answer.

[cairijun]

Hi @nabiu256 are you still working on this? I tried your patch recently (on develop branch) and I think it need some modifications to ensure reasoning_contents are sent back to LLM:

     form_messages = function(self, messages)
-      messages = adapter_utils.merge_messages(messages)
+      messages = adapter_utils.merge_messages(messages, { "tools", "reasoning" })
       messages = adapter_utils.merge_system_messages(messages)

+    form_reasoning = function(self, data)
+      local content = vim
+        .iter(data)
+        :map(function(item)
+          return item.content
+        end)
+        :join("")
+      return { content = content }
+    end,

     parse_message_meta = function(self, data)
       local extra = data.extra
-      if extra.reasoning_content then
+      if extra.reasoning_content and extra.reasoning_content ~= "" then
         data.output.reasoning = { content = extra.reasoning_content }