feat(adapters): add support for gemini-3 in the gemini adapter (#2411)

feat(adapters): add support for gemini-3

Co-authored-by: Oli Morris <[email protected]>

Author: olimorris

lua/codecompanion/adapters/http/gemini.lua

@@ -57,7 +57,42 @@ return {
       return openai.handlers.form_tools(self, tools)
     end,
     form_messages = function(self, messages)
-      return openai.handlers.form_messages(self, messages)
+      local result = openai.handlers.form_messages(self, messages)
+
+      local STANDARD_TOOL_CALL_FIELDS = {
+        "id",
+        "type",
+        "function",
+        "_index",
+      }
+
+      -- Post-process to preserve extra fields (like thought signatures)
+      -- Ref: https://ai.google.dev/gemini-api/docs/thought-signatures#openai
+      for _, msg in ipairs(result.messages) do
+        local original_msg = nil
+        for _, orig in ipairs(messages) do
+          if orig.role == msg.role and orig.tools and orig.tools.calls then
+            original_msg = orig
+            break
+          end
+        end
+
+        -- If we have tool_calls in the original message then preserve non-standard fields
+        if msg.tool_calls and original_msg and original_msg.tools and original_msg.tools.calls then
+          for i, tool_call in ipairs(msg.tool_calls) do
+            local original_tool = original_msg.tools.calls[i]
+            if original_tool then
+              for key, value in pairs(original_tool) do
+                if not vim.tbl_contains(STANDARD_TOOL_CALL_FIELDS, key) then
+                  tool_call[key] = value
+                end
+              end
+            end
+          end
+        end
+      end
+
+      return result
     end,
     chat_output = function(self, data, tools)
       return openai.handlers.chat_output(self, data, tools)
@@ -86,6 +121,7 @@ return {
       desc = "The model that will complete your prompt. See https://ai.google.dev/gemini-api/docs/models/gemini#model-variations for additional details and options.",
       default = "gemini-2.5-flash",
       choices = {
+        ["gemini-3-pro-preview"] = { formatted_name = "Gemini 3 Pro", opts = { can_reason = true, has_vision = true } },
         ["gemini-2.5-pro"] = { formatted_name = "Gemini 2.5 Pro", opts = { can_reason = true, has_vision = true } },
         ["gemini-2.5-flash"] = { formatted_name = "Gemini 2.5 Flash", opts = { can_reason = true, has_vision = true } },
         ["gemini-2.5-flash-preview-05-20"] = {

lua/codecompanion/adapters/http/openai.lua

@@ -1,5 +1,6 @@
 local adapter_utils = require("codecompanion.utils.adapters")
 local log = require("codecompanion.utils.log")
+
 local CONSTANTS = {
   STANDARD_MESSAGE_FIELDS = {
     -- fields that are defined in the standard openai chat-completion API (inc. streaming and non-streaming)
@@ -14,9 +15,8 @@ local CONSTANTS = {
 }
 
 ---Find the non-standard fields in the `message` or `delta` that are not in the standard OpenAI chat-completion specs.
----Returns `nil` if not found.
 ---@param delta table?
----@return table?
+---@return table|nil
 local function find_extra_fields(delta)
   if delta == nil then
     return nil
@@ -125,6 +125,7 @@ return {
                   id = tool_call.id,
                   ["function"] = tool_call["function"],
                   type = tool_call.type,
+                  -- Include a _meta field to hold everything else
                 }
               end)
               :totable()
@@ -218,6 +219,40 @@ return {
         return nil
       end
 
+      -- Define standard tool_call fields
+      local STANDARD_TOOL_CALL_FIELDS = {
+        "id",
+        "type",
+        "function",
+        "index",
+      }
+
+      ---Helper to create any tool data
+      ---@param tool table
+      ---@param index number
+      ---@param id string
+      ---@return table
+      local function create_tool_data(tool, index, id)
+        local tool_data = {
+          _index = index,
+          id = id,
+          type = tool.type,
+          ["function"] = {
+            name = tool["function"]["name"],
+            arguments = tool["function"]["arguments"] or "",
+          },
+        }
+
+        -- Preserve any non-standard fields as-is
+        for key, value in pairs(tool) do
+          if not vim.tbl_contains(STANDARD_TOOL_CALL_FIELDS, key) then
+            tool_data[key] = value
+          end
+        end
+
+        return tool_data
+      end
+
       -- Process tool calls from all choices
       if self.opts.tools and tools then
         for _, choice in ipairs(json.choices) do
@@ -248,26 +283,10 @@ return {
                 end
 
                 if not found then
-                  table.insert(tools, {
-                    _index = tool_index,
-                    id = id,
-                    type = tool.type,
-                    ["function"] = {
-                      name = tool["function"]["name"],
-                      arguments = tool["function"]["arguments"] or "",
-                    },
-                  })
+                  table.insert(tools, create_tool_data(tool, tool_index, id))
                 end
               else
-                table.insert(tools, {
-                  _index = i,
-                  id = id,
-                  type = tool.type,
-                  ["function"] = {
-                    name = tool["function"]["name"],
-                    arguments = tool["function"]["arguments"],
-                  },
-                })
+                table.insert(tools, create_tool_data(tool, i, id))
               end
             end
           end
@@ -283,12 +302,12 @@ return {
       end
 
       return {
-        status = "success",
+        extra = find_extra_fields(delta),
         output = {
           role = delta.role,
           content = delta.content,
         },
-        extra = find_extra_fields(delta),
+        status = "success",
       }
     end,
 

tests/adapters/http/stubs/gemini_tools_thought_streaming.txt

@@ -0,0 +1 @@
+data: {"choices":[{"delta":{"role":"assistant","tool_calls":[{"extra_content":{"google":{"thought_signature":"Eo123"}},"function":{"arguments":"{\"query\":\"README.md\"}","name":"file_search"},"id":"function-call-13802169321809035407","type":"function"}]},"index":0}],"created":1763566011,"id":"u-EdaYzRJ6zk7M8Pqdel4AU","model":"gemini-3-pro-preview","object":"chat.completion.chunk","usage":{"completion_tokens":18,"prompt_tokens":5171,"total_tokens":5239}}

tests/adapters/http/test_gemini.lua

@@ -106,6 +106,76 @@ T["Gemini adapter"]["Streaming"]["can process tools"] = function()
   h.eq(tool_output, tools)
 end
 
+T["Gemini adapter"]["Streaming"]["can preserve thought signatures in tool calls"] = function()
+  local tools = {}
+  local lines = vim.fn.readfile("tests/adapters/http/stubs/gemini_tools_thought_streaming.txt")
+  for _, line in ipairs(lines) do
+    adapter.handlers.chat_output(adapter, line, tools)
+  end
+
+  local tool_output = {
+    {
+      _index = 1,
+      ["function"] = {
+        arguments = '{"query":"README.md"}',
+        name = "file_search",
+      },
+      id = "function-call-13802169321809035407",
+      type = "function",
+      extra_content = {
+        google = {
+          thought_signature = "Eo123",
+        },
+      },
+    },
+  }
+
+  h.eq(tool_output, tools)
+end
+
+T["Gemini adapter"]["Streaming"]["can send thought signatures back in messages"] = function()
+  local messages = {
+    {
+      content = "Search for README.md",
+      role = "user",
+    },
+    {
+      role = "assistant",
+      tools = {
+        calls = {
+          {
+            _index = 1,
+            id = "function-call-13802169321809035407",
+            type = "function",
+            ["function"] = {
+              name = "file_search",
+              arguments = '{"query":"README.md"}',
+            },
+            extra_content = {
+              google = {
+                thought_signature = "Eo123",
+              },
+            },
+          },
+        },
+      },
+    },
+    {
+      role = "user",
+      tools = {
+        call_id = "function-call-13802169321809035407",
+      },
+      content = '{"file":"README.md","contents":"..."}',
+    },
+  }
+
+  local output = adapter.handlers.form_messages(adapter, messages)
+
+  -- Verify the thought signature is preserved in the tool_calls
+  local assistant_message = output.messages[2]
+  h.eq("Eo123", assistant_message.tool_calls[1].extra_content.google.thought_signature)
+end
+
 T["Gemini adapter"]["No Streaming"] = new_set({
   hooks = {
     pre_case = function()