fix: Allow different model names depending on task (#9)

* fix: Allow different model names depending on task

* add gemini 2.5 flash and pro

* fix anthropic thinking models

src/nodes/generate-message.ts

@@ -1,5 +1,5 @@
 import { GraphState, GraphConfig, GraphUpdate, PlanItem } from "../types.js";
-import { loadModel } from "../utils/load-model.js";
+import { loadModel, Task } from "../utils/load-model.js";
 import { shellTool, applyPatchTool } from "../tools/index.js";
 import { formatPlanPrompt } from "../utils/plan-prompt.js";
 
@@ -58,7 +58,7 @@ export async function generateAction(
   state: GraphState,
   config: GraphConfig,
 ): Promise<GraphUpdate> {
-  const model = await loadModel(config);
+  const model = await loadModel(config, Task.ACTION_GENERATOR);
   const tools = [shellTool, applyPatchTool];
   const modelWithTools = model.bindTools(tools, { tool_choice: "auto" });
 

src/nodes/generate-plan.ts

@@ -1,6 +1,6 @@
 import { sessionPlanTool } from "../tools/index.js";
 import { GraphState, GraphConfig, GraphUpdate } from "../types.js";
-import { loadModel } from "../utils/load-model.js";
+import { loadModel, Task } from "../utils/load-model.js";
 
 const systemPrompt = `You are operating as a terminal-based agentic coding assistant built by LangChain. It wraps LLM models to enable natural language interaction with a local codebase. You are expected to be precise, safe, and helpful.
 
@@ -19,7 +19,7 @@ export async function generatePlan(
   state: GraphState,
   config: GraphConfig,
 ): Promise<GraphUpdate> {
-  const model = await loadModel(config);
+  const model = await loadModel(config, Task.PLANNER);
   const modelWithTools = model.bindTools([sessionPlanTool], {
     tool_choice: "auto",
   });

src/nodes/progress-plan-step.ts

@@ -1,6 +1,6 @@
 import { z } from "zod";
 import { GraphConfig, GraphState, GraphUpdate, PlanItem } from "../types.js";
-import { loadModel } from "../utils/load-model.js";
+import { loadModel, Task } from "../utils/load-model.js";
 import { formatPlanPrompt } from "../utils/plan-prompt.js";
 
 const systemPrompt = `You are operating as a terminal-based agentic coding assistant built by LangChain. It wraps LLM models to enable natural language interaction with a local codebase. You are expected to be precise, safe, and helpful.
@@ -35,7 +35,7 @@ export async function progressPlanStep(
   state: GraphState,
   config: GraphConfig,
 ): Promise<GraphUpdate> {
-  const model = await loadModel(config);
+  const model = await loadModel(config, Task.PROGRESS_PLAN_CHECKER);
   const modelWithTools = model.bindTools([confirmTaskCompletionTool], {
     tool_choice: confirmTaskCompletionTool.name,
   });

src/nodes/rewrite-plan.ts

@@ -1,5 +1,5 @@
 import { GraphState, GraphConfig, GraphUpdate } from "../types.js";
-import { loadModel } from "../utils/load-model.js";
+import { loadModel, Task } from "../utils/load-model.js";
 import { sessionPlanTool } from "../tools/index.js";
 
 const systemPrompt = `You are operating as a terminal-based agentic coding assistant built by LangChain. It wraps LLM models to enable natural language interaction with a local codebase. You are expected to be precise, safe, and helpful.
@@ -36,7 +36,7 @@ export async function rewritePlan(
     throw new Error("No plan change request found.");
   }
 
-  const model = await loadModel(config);
+  const model = await loadModel(config, Task.PLANNER);
   const modelWithTools = model.bindTools([sessionPlanTool], {
     // The model should always call the tool when rewriting the plan.
     tool_choice: sessionPlanTool.name,

src/types.ts

@@ -47,16 +47,64 @@ export const GraphAnnotation = Annotation.Root({
 export type GraphState = typeof GraphAnnotation.State;
 export type GraphUpdate = typeof GraphAnnotation.Update;
 
-export const MCPConfig = z.object({
+const MODEL_OPTIONS = [
-  /**
+  {
-   * The MCP server URL.
+    label: "Claude Sonnet 4 (Extended Thinking)",
-   */
+    value: "anthropic:extended-thinking:claude-sonnet-4-0",
-  url: z.string(),
+  },
-  /**
+  {
-   * The list of tools to provide to the LLM.
+    label: "Claude Opus 4 (Extended Thinking)",
-   */
+    value: "anthropic:extended-thinking:claude-opus-4-0",
-  tools: z.array(z.string()),
+  },
-});
+  {
+    label: "Claude Sonnet 4",
+    value: "anthropic:claude-sonnet-4-0",
+  },
+  {
+    label: "Claude Opus 4",
+    value: "anthropic:claude-opus-4-0",
+  },
+  {
+    label: "Claude 3.7 Sonnet",
+    value: "anthropic:claude-3-7-sonnet-latest",
+  },
+  {
+    label: "Claude 3.5 Sonnet",
+    value: "anthropic:claude-3-5-sonnet-latest",
+  },
+  {
+    label: "o4",
+    value: "openai:o4",
+  },
+  {
+    label: "o4 mini",
+    value: "openai:o4-mini",
+  },
+  {
+    label: "o3",
+    value: "openai:o3",
+  },
+  {
+    label: "o3 mini",
+    value: "openai:o3-mini",
+  },
+  {
+    label: "GPT 4o",
+    value: "openai:gpt-4o",
+  },
+  {
+    label: "GPT 4.1",
+    value: "openai:gpt-4.1",
+  },
+  {
+    label: "Gemini 2.5 Pro Preview",
+    value: "google-genai:gemini-2.5-pro-preview-05-06",
+  },
+  {
+    label: "Gemini 2.5 Flash Preview",
+    value: "google-genai:gemini-2.5-flash-preview-05-20",
+  },
+];
 
 export const GraphConfiguration = z.object({
   /**
@@ -85,55 +133,28 @@ export const GraphConfiguration = z.object({
    */
   sandbox_language: z.enum(["js", "python"]).optional().langgraph.metadata({}),
   /**
-   * The model ID to use for the reflection generation.
+   * The model ID to use for the planning step.
-   * Should be in the format `provider:model_name`.
+   * This includes initial planning, and rewriting.
-   * Defaults to `anthropic:claude-3-7-sonnet-latest`.
+   * @default "anthropic:extended-thinking:claude-sonnet-4-0"
    */
-  modelName: z
+  plannerModelName: z
     .string()
     .optional()
     .langgraph.metadata({
       x_lg_ui_config: {
         type: "select",
-        default: "anthropic:claude-3-7-sonnet-latest",
+        default: "anthropic:extended-thinking:claude-sonnet-4-0",
-        description: "The model to use in all generations",
+        description: "The model to use for planning",
-        options: [
+        options: MODEL_OPTIONS,
-          {
-            label: "Claude 3.7 Sonnet",
-            value: "anthropic:claude-3-7-sonnet-latest",
-          },
-          {
-            label: "Claude 3.5 Sonnet",
-            value: "anthropic:claude-3-5-sonnet-latest",
-          },
-          {
-            label: "GPT 4o",
-            value: "openai:gpt-4o",
-          },
-          {
-            label: "GPT 4.1",
-            value: "openai:gpt-4.1",
-          },
-          {
-            label: "o3",
-            value: "openai:o3",
-          },
-          {
-            label: "o3 mini",
-            value: "openai:o3-mini",
-          },
-          {
-            label: "o4",
-            value: "openai:o4",
-          },
-        ],
       },
     }),
   /**
-   * The temperature to use for the reflection generation.
+   * The temperature to use for the planning step.
-   * Defaults to `0.7`.
+   * This includes initial planning, and rewriting.
+   * If selecting a reasoning model, this will be ignored.
+   * @default 0
    */
-  temperature: z
+  plannerTemperature: z
     .number()
     .optional()
     .langgraph.metadata({
@@ -146,18 +167,72 @@ export const GraphConfiguration = z.object({
         description: "Controls randomness (0 = deterministic, 2 = creative)",
       },
     }),
+
   /**
-   * The maximum number of tokens to generate.
+   * The model ID to use for action generation.
-   * Defaults to `1000`.
+   * @default "anthropic:claude-sonnet-4-0"
    */
-  maxTokens: z
+  actionGeneratorModelName: z
+    .string()
+    .optional()
+    .langgraph.metadata({
+      x_lg_ui_config: {
+        type: "select",
+        default: "anthropic:claude-sonnet-4-0",
+        description: "The model to use for action generation",
+        options: MODEL_OPTIONS,
+      },
+    }),
+  /**
+   * The temperature to use for action generation.
+   * If selecting a reasoning model, this will be ignored.
+   * @default 0
+   */
+  actionGeneratorTemperature: z
     .number()
     .optional()
     .langgraph.metadata({
       x_lg_ui_config: {
-        type: "number",
+        type: "slider",
-        min: 1,
+        default: 0,
-        description: "The maximum number of tokens to generate",
+        min: 0,
+        max: 2,
+        step: 0.1,
+        description: "Controls randomness (0 = deterministic, 2 = creative)",
+      },
+    }),
+
+  /**
+   * The model ID to use for progress plan checking.
+   * @default "anthropic:claude-sonnet-4-0"
+   */
+  progressPlanCheckerModelName: z
+    .string()
+    .optional()
+    .langgraph.metadata({
+      x_lg_ui_config: {
+        type: "select",
+        default: "anthropic:claude-sonnet-4-0",
+        description: "The model to use for progress plan checking",
+        options: MODEL_OPTIONS,
+      },
+    }),
+  /**
+   * The temperature to use for progress plan checking.
+   * If selecting a reasoning model, this will be ignored.
+   * @default 0
+   */
+  progressPlanCheckerTemperature: z
+    .number()
+    .optional()
+    .langgraph.metadata({
+      x_lg_ui_config: {
+        type: "slider",
+        default: 0,
+        min: 0,
+        max: 2,
+        step: 0.1,
+        description: "Controls randomness (0 = deterministic, 2 = creative)",
       },
     }),
 });

src/utils/load-model.ts

@@ -1,15 +1,55 @@
 import { initChatModel } from "langchain/chat_models/universal";
 import { GraphConfig } from "../types.js";
 
-export async function loadModel(config: GraphConfig) {
+export enum Task {
+  PLANNER = "planner",
+  ACTION_GENERATOR = "actionGenerator",
+  PROGRESS_PLAN_CHECKER = "progressPlanChecker",
+}
+
+const TASK_TO_CONFIG_DEFAULTS_MAP = {
+  [Task.PLANNER]: {
+    modelName: "anthropic:extended-thinking:claude-sonnet-4-0",
+    temperature: 0,
+  },
+  [Task.ACTION_GENERATOR]: {
+    modelName: "anthropic:claude-sonnet-4-0",
+    temperature: 0,
+  },
+  [Task.PROGRESS_PLAN_CHECKER]: {
+    modelName: "anthropic:claude-sonnet-4-0",
+    temperature: 0,
+  },
+};
+
+export async function loadModel(config: GraphConfig, task: Task) {
   const modelStr =
-    config.configurable?.modelName ?? "anthropic:claude-3-7-sonnet-latest";
+    config.configurable?.[`${task}ModelName`] ??
+    TASK_TO_CONFIG_DEFAULTS_MAP[task].modelName;
+  const temperature =
+    config.configurable?.[`${task}Temperature`] ??
+    TASK_TO_CONFIG_DEFAULTS_MAP[task].temperature;
+
   const [modelProvider, ...modelNameParts] = modelStr.split(":");
+
+  let thinkingModel = false;
+  if (modelNameParts[0] === "extended-thinking") {
+    // Using a thinking model. Remove it from the model name.
+    modelNameParts.shift();
+    thinkingModel = true;
+  }
+
   const modelName = modelNameParts.join(":");
+  if (modelProvider === "openai" && modelName.startsWith("o")) {
+    thinkingModel = true;
+  }
+
   const model = await initChatModel(modelName, {
     modelProvider,
-    temperature: config.configurable?.temperature ?? 0,
+    temperature: thinkingModel ? undefined : temperature,
-    maxTokens: config.configurable?.maxTokens ?? undefined,
+    ...(thinkingModel && modelProvider === "anthropic"
+      ? { thinking: { budgetTokens: 5000, type: "enabled" } }
+      : {}),
   });
 
   return model;