add gemini support

Author: olimorris

lua/codecompanion/adapters/gemini.lua

@@ -10,6 +10,7 @@ return {
   },
   opts = {
     stream = true,
+    tools = true,
   },
   features = {
     text = true,
@@ -35,11 +36,14 @@ return {
     form_parameters = function(self, params, messages)
       return openai.handlers.form_parameters(self, params, messages)
     end,
+    form_tools = function(self, tools)
+      return openai.handlers.form_tools(self, tools)
+    end,
     form_messages = function(self, messages)
       return openai.handlers.form_messages(self, messages)
     end,
-    chat_output = function(self, data)
-      return openai.handlers.chat_output(self, data)
+    chat_output = function(self, data, tools)
+      return openai.handlers.chat_output(self, data, tools)
     end,
     inline_output = function(self, data, context)
       return openai.handlers.inline_output(self, data, context)

lua/codecompanion/adapters/openai.lua

@@ -148,9 +148,9 @@ return {
             end
 
             if self.opts.tools and delta.tool_calls and tools then
-              for _, tool in ipairs(delta.tool_calls) do
+              for i, tool in ipairs(delta.tool_calls) do
                 if self.opts.stream then
-                  local index = tostring(tool.index)
+                  local index = tool.index and tostring(tool.index) or tostring(i)
                   if not vim.tbl_contains(vim.tbl_keys(tools), index) then
                     tools[index] = {
                       name = tool["function"]["name"],
@@ -159,7 +159,8 @@ return {
                   end
                   tools[index]["arguments"] = (tools[index]["arguments"] or "") .. (tool["function"]["arguments"] or "")
                 else
-                  tools[tool.id] = {
+                  local id = (tool.id and tool.id ~= "") and tostring(tool.id) or tostring(i)
+                  tools[id] = {
                     name = tool["function"]["name"],
                     arguments = vim.json.decode(tool["function"]["arguments"]),
                   }

lua/codecompanion/strategies/chat/agents/tools/weather.lua

@@ -11,6 +11,7 @@ return {
       }
     end,
   },
+  system_prompt = "The weather tool must only be called once for each location",
   schema = {
     type = "function",
     ["function"] = {

tests/adapters/stubs/gemini_tools_no_streaming.txt

@@ -0,0 +1,37 @@
+{
+    "choices": [
+        {
+            "finish_reason": "tool_calls",
+            "index": 0,
+            "message": {
+                "role": "assistant",
+                "tool_calls": [
+                    {
+                        "function": {
+                            "arguments": "{\"location\":\"London, UK\",\"units\":\"celsius\"}",
+                            "name": "weather"
+                        },
+                        "id": "",
+                        "type": "function"
+                    },
+                    {
+                        "function": {
+                            "arguments": "{\"units\":\"celsius\",\"location\":\"Paris, France\"}",
+                            "name": "weather"
+                        },
+                        "id": "",
+                        "type": "function"
+                    }
+                ]
+            }
+        }
+    ],
+    "created": 1743631193,
+    "model": "gemini-2.0-flash",
+    "object": "chat.completion",
+    "usage": {
+        "completion_tokens": 16,
+        "prompt_tokens": 62,
+        "total_tokens": 78
+    }
+}

tests/adapters/stubs/gemini_tools_streaming.txt

@@ -0,0 +1 @@
+data: {"choices":[{"delta":{"role":"assistant","tool_calls":[{"function":{"arguments":"{\"units\":\"celsius\",\"location\":\"London\"}","name":"weather"},"id":"","type":"function"},{"function":{"arguments":"{\"units\":\"celsius\",\"location\":\"Paris\"}","name":"weather"},"id":"","type":"function"}]},"finish_reason":"tool_calls","index":0}],"created":1743628522,"model":"gemini-2.5-pro-exp-03-25","object":"chat.completion.chunk","usage":{"completion_tokens":38,"prompt_tokens":504,"total_tokens":542}}

tests/adapters/test_gemini.lua

@@ -48,6 +48,13 @@ T["Gemini adapter"]["can form messages to be sent to the API"] = function()
   h.eq(output, adapter.handlers.form_messages(adapter, messages))
 end
 
+T["Gemini adapter"]["it can form tools to be sent to the API"] = function()
+  local weather = require("tests/strategies/chat/agents/tools/stubs/weather").schema
+  local tools = { weather = { weather } }
+
+  h.eq({ tools = { weather } }, adapter.handlers.form_tools(adapter, tools))
+end
+
 T["Gemini adapter"]["Streaming"] = new_set()
 
 T["Gemini adapter"]["Streaming"]["can output streamed data into the chat buffer"] = function()
@@ -63,6 +70,27 @@ T["Gemini adapter"]["Streaming"]["can output streamed data into the chat buffer"
   h.expect_starts_with("Elegant, dynamic", output)
 end
 
+T["Gemini adapter"]["Streaming"]["can process tools"] = function()
+  local tools = {}
+  local lines = vim.fn.readfile("tests/adapters/stubs/gemini_tools_streaming.txt")
+  for _, line in ipairs(lines) do
+    adapter.handlers.chat_output(adapter, line, tools)
+  end
+
+  local tool_output = {
+    ["1"] = {
+      arguments = '{"units":"celsius","location":"London"}',
+      name = "weather",
+    },
+    ["2"] = {
+      arguments = '{"units":"celsius","location":"Paris"}',
+      name = "weather",
+    },
+  }
+
+  h.eq(tool_output, tools)
+end
+
 T["Gemini adapter"]["No Streaming"] = new_set({
   hooks = {
     pre_case = function()
@@ -85,6 +113,35 @@ T["Gemini adapter"]["No Streaming"]["can output for the chat buffer"] = function
   h.expect_starts_with("Elegant, dynamic.", adapter.handlers.chat_output(adapter, json).output.content)
 end
 
+T["Gemini adapter"]["No Streaming"]["can process tools"] = function()
+  local data = vim.fn.readfile("tests/adapters/stubs/gemini_tools_no_streaming.txt")
+  data = table.concat(data, "\n")
+
+  local tools = {}
+
+  -- Match the format of the actual request
+  local json = { body = data }
+  adapter.handlers.chat_output(adapter, json, tools)
+
+  local tool_output = {
+    ["1"] = {
+      arguments = {
+        location = "London, UK",
+        units = "celsius",
+      },
+      name = "weather",
+    },
+    ["2"] = {
+      arguments = {
+        location = "Paris, France",
+        units = "celsius",
+      },
+      name = "weather",
+    },
+  }
+  h.eq(tool_output, tools)
+end
+
 T["Gemini adapter"]["No Streaming"]["can output for the inline assistant"] = function()
   local data = vim.fn.readfile("tests/adapters/stubs/gemini_no_streaming.txt")
   data = table.concat(data, "\n")