feat(executor): add Devin (Codeium Cascade) provider

docs/devin.md

@@ -0,0 +1,196 @@
+# Devin (Codeium Cascade) guide
+
+CLIProxyAPI can use Devin's Codeium Cascade backend as a provider, exposing Devin's free models through the standard OpenAI chat completions API.
+
+It supports:
+
+- streaming and non-streaming chat completions
+- system prompts
+- multi-turn conversations
+- tool calling (function calling) with multi-turn tool results
+- reasoning/thinking tokens (exposed as `reasoning` in the response)
+
+## Available models
+
+| Model ID | Description |
+|----------|-------------|
+| `glm-5-2` | GLM-5.2 High (default) |
+| `glm-5-2-1m` | GLM-5.2 High with 1M token context |
+| `glm-5-2-max` | GLM-5.2 Max |
+| `swe-1-7` | SWE-1.7 |
+| `swe-1-7-medium` | SWE-1.7 Medium |
+| `swe-1-6` | SWE-1.6 |
+
+## Auth configuration
+
+The Devin provider uses the same session token as the Devin CLI. The token is found in `~/.local/share/devin/credentials.toml` under the `session_token` field.
+
+Create a JSON file in the auth directory (e.g., `auths/devin.json`):
+
+```json
+{
+  "type": "devin",
+  "devin_session_token": "devin-session-token$eyJhbGci..."
+}
+```
+
+## Usage
+
+### Basic chat completion
+
+```bash
+curl http://127.0.0.1:18499/v1/chat/completions \
+  -H "Authorization: Bearer YOUR_API_KEY" \
+  -H "Content-Type: application/json" \
+  -d '{
+    "model": "glm-5-2",
+    "messages": [{"role": "user", "content": "Hello!"}],
+    "stream": false
+  }'
+```
+
+### Streaming
+
+```bash
+curl http://127.0.0.1:18499/v1/chat/completions \
+  -H "Authorization: Bearer YOUR_API_KEY" \
+  -H "Content-Type: application/json" \
+  -d '{
+    "model": "glm-5-2",
+    "messages": [{"role": "user", "content": "Hello!"}],
+    "stream": true
+  }'
+```
+
+### System prompt
+
+```bash
+curl http://127.0.0.1:18499/v1/chat/completions \
+  -H "Authorization: Bearer YOUR_API_KEY" \
+  -H "Content-Type: application/json" \
+  -d '{
+    "model": "glm-5-2",
+    "messages": [
+      {"role": "system", "content": "You are a helpful assistant that always replies in one sentence."},
+      {"role": "user", "content": "Tell me about Go."}
+    ]
+  }'
+```
+
+### Tool calling
+
+The Devin provider supports OpenAI-compatible tool calling. Tool definitions are translated to Devin's `ChatToolDefinition` protobuf format, and tool call deltas in the response are converted to OpenAI's streaming tool call format.
+
+```bash
+curl http://127.0.0.1:18499/v1/chat/completions \
+  -H "Authorization: Bearer YOUR_API_KEY" \
+  -H "Content-Type: application/json" \
+  -d '{
+    "model": "glm-5-2",
+    "messages": [
+      {"role": "user", "content": "What is the weather in San Francisco?"}
+    ],
+    "tools": [{
+      "type": "function",
+      "function": {
+        "name": "get_weather",
+        "description": "Get the current weather in a given location",
+        "parameters": {
+          "type": "object",
+          "properties": {
+            "location": {"type": "string", "description": "The city and state, e.g. San Francisco, CA"}
+          },
+          "required": ["location"]
+        }
+      }
+    }]
+  }'
+```
+
+Response:
+
+```json
+{
+  "id": "chatcmpl-bot-...",
+  "object": "chat.completion",
+  "model": "glm-5-2",
+  "choices": [{
+    "index": 0,
+    "message": {
+      "role": "assistant",
+      "content": null,
+      "tool_calls": [{
+        "id": "chatcmpl-tool-...",
+        "type": "function",
+        "function": {
+          "name": "get_weather",
+          "arguments": "{\"location\": \"San Francisco, CA\"}"
+        }
+      }]
+    },
+    "finish_reason": "stop"
+  }]
+}
+```
+
+### Multi-turn with tool results
+
+After receiving a tool call, execute the function and feed the result back as a `tool` role message:
+
+```bash
+curl http://127.0.0.1:18499/v1/chat/completions \
+  -H "Authorization: Bearer YOUR_API_KEY" \
+  -H "Content-Type: application/json" \
+  -d '{
+    "model": "glm-5-2",
+    "messages": [
+      {"role": "user", "content": "What is the weather in San Francisco?"},
+      {"role": "assistant", "content": null, "tool_calls": [{"id": "call_abc123", "type": "function", "function": {"name": "get_weather", "arguments": "{\"location\": \"San Francisco, CA\"}"}}]},
+      {"role": "tool", "tool_call_id": "call_abc123", "content": "The weather in San Francisco, CA is 62 degrees and foggy."}
+    ],
+    "tools": [{
+      "type": "function",
+      "function": {
+        "name": "get_weather",
+        "description": "Get the current weather in a given location",
+        "parameters": {"type": "object", "properties": {"location": {"type": "string"}}, "required": ["location"]}
+      }
+    }]
+  }'
+```
+
+Response:
+
+```json
+{
+  "id": "chatcmpl-bot-...",
+  "object": "chat.completion",
+  "model": "glm-5-2",
+  "choices": [{
+    "index": 0,
+    "message": {
+      "role": "assistant",
+      "content": "The current weather in San Francisco is **62°F** and **foggy**. Classic San Francisco! 🌁"
+    },
+    "finish_reason": "stop"
+  }]
+}
+```
+
+## How it works
+
+The Devin executor translates OpenAI chat completion requests into Devin's Connect-RPC protobuf format (`GetChatMessageRequest`) and sends them to `server.codeium.com`. Streaming responses are parsed from Connect frames (`GetChatMessageResponse`) and converted to OpenAI SSE chunks.
+
+| OpenAI field | Devin protobuf field |
+|--------------|---------------------|
+| `messages[system]` | `prompt` (field 2) |
+| `messages[user/assistant/tool]` | `chat_message_prompts` (field 3, repeated) |
+| `tools` | `tools` (field 10, repeated) |
+| `temperature` | `configuration.temperature` (field 8.5) |
+| `max_tokens` | `configuration.max_tokens` (field 8.2) |
+| `top_p` | `configuration.top_p` (field 8.8) |
+| response `content` | `delta_text` (field 3) |
+| response `reasoning` | `delta_thinking` (field 9) |
+| response `tool_calls` | `delta_tool_calls` (field 6, repeated) |
+| response `finish_reason` | `stop_reason` (field 5) |
+| response `usage` | `usage` (field 7) |

internal/registry/model_definitions.go

@@ -31,6 +31,7 @@ type staticModelsJSON struct {
 	Qoder       []*ModelInfo `json:"qoder"`
 	Antigravity []*ModelInfo `json:"antigravity"`
 	XAI         []*ModelInfo `json:"xai"`
+	Devin       []*ModelInfo `json:"devin"`
 }
 
 // GetClaudeModels returns the standard Claude model definitions.
@@ -888,3 +889,8 @@ func GetAmazonQModels() []*ModelInfo {
 func GetQoderModels() []*ModelInfo {
 	return cloneModelInfos(getModels().Qoder)
 }
+
+// GetDevinModels returns the standard Devin model definitions.
+func GetDevinModels() []*ModelInfo {
+	return cloneModelInfos(getModels().Devin)
+}