diff --git a/apps/open-swe/src/index.ts b/apps/open-swe/src/index.ts
index 0d398f0a..089f7438 100644
--- a/apps/open-swe/src/index.ts
+++ b/apps/open-swe/src/index.ts
@@ -32,8 +32,8 @@ import { plannerGraph } from "./subgraphs/index.js";
 async function routeGeneratedAction(
   state: GraphState,
 ): Promise<"open-pr" | "take-action" | "request-help" | Send> {
-  const { messages } = state;
-  const lastMessage = messages[messages.length - 1];
+  const { internalMessages } = state;
+  const lastMessage = internalMessages[internalMessages.length - 1];
 
   // If the message is an AI message, and it has tool calls, we should take action.
   if (isAIMessage(lastMessage) && lastMessage.tool_calls?.length) {
diff --git a/apps/open-swe/src/nodes/diagnose-error.ts b/apps/open-swe/src/nodes/diagnose-error.ts
index 9cd7f451..6436ed4f 100644
--- a/apps/open-swe/src/nodes/diagnose-error.ts
+++ b/apps/open-swe/src/nodes/diagnose-error.ts
@@ -101,7 +101,7 @@ export async function diagnoseError(
   state: GraphState,
   config: GraphConfig,
 ): Promise<GraphUpdate> {
-  const lastFailedAction = state.messages.findLast(
+  const lastFailedAction = state.internalMessages.findLast(
     (m) => isToolMessage(m) && m.status === "error",
   );
   if (!lastFailedAction?.content) {
@@ -113,6 +113,7 @@ export async function diagnoseError(
   const model = await loadModel(config, Task.SUMMARIZER);
   const modelWithTools = model.bindTools([diagnoseErrorTool], {
     tool_choice: diagnoseErrorTool.name,
+    parallel_tool_calls: false,
   });
 
   const response = await modelWithTools.invoke([
@@ -126,7 +127,7 @@ export async function diagnoseError(
     },
     {
       role: "user",
-      content: formatUserPrompt(state.messages),
+      content: formatUserPrompt(state.internalMessages),
     },
   ]);
 
@@ -153,5 +154,6 @@ export async function diagnoseError(
 
   return {
     messages: [response, toolMessage],
+    internalMessages: [response, toolMessage],
   };
 }
diff --git a/apps/open-swe/src/nodes/generate-conclusion.ts b/apps/open-swe/src/nodes/generate-conclusion.ts
index 1d6acc71..bcacbef9 100644
--- a/apps/open-swe/src/nodes/generate-conclusion.ts
+++ b/apps/open-swe/src/nodes/generate-conclusion.ts
@@ -39,12 +39,12 @@ export async function generateConclusion(
 ): Promise<GraphUpdate> {
   const model = await loadModel(config, Task.SUMMARIZER);
 
-  const userRequest = getUserRequest(state.messages);
+  const userRequest = getUserRequest(state.internalMessages);
   const userMessage = `The user's initial request is as follows:
 ${userRequest || "No user message found"}
 
 The conversation history is as follows:
-${state.messages.map(getMessageString).join("\n")}
+${state.internalMessages.map(getMessageString).join("\n")}
 
 Given all of this, please respond with the concise conclusion. Do not include any additional text besides the conclusion.`;
 
@@ -71,6 +71,7 @@ Given all of this, please respond with the concise conclusion. Do not include an
 
   return {
     messages: [response],
+    internalMessages: [response],
     plan: updatedTaskPlan,
   };
 }
diff --git a/apps/open-swe/src/nodes/generate-message.ts b/apps/open-swe/src/nodes/generate-message.ts
index 19d983fd..194c2e7e 100644
--- a/apps/open-swe/src/nodes/generate-message.ts
+++ b/apps/open-swe/src/nodes/generate-message.ts
@@ -147,14 +147,17 @@ export async function generateAction(
     requestHumanHelpTool,
     updatePlanTool,
   ];
-  const modelWithTools = model.bindTools(tools, { tool_choice: "auto" });
+  const modelWithTools = model.bindTools(tools, {
+    tool_choice: "auto",
+    parallel_tool_calls: false,
+  });
 
   const response = await modelWithTools.invoke([
     {
       role: "system",
       content: formatPrompt(state),
     },
-    ...state.messages,
+    ...state.internalMessages,
   ]);
 
   const hasToolCalls = !!response.tool_calls?.length;
@@ -178,6 +181,7 @@ export async function generateAction(
 
   return {
     messages: [response],
+    internalMessages: [response],
     ...(newSandboxSessionId && { sandboxSessionId: newSandboxSessionId }),
   };
 }
diff --git a/apps/open-swe/src/nodes/interrupt-plan.ts b/apps/open-swe/src/nodes/interrupt-plan.ts
index 2b9327f2..a9e03dbf 100644
--- a/apps/open-swe/src/nodes/interrupt-plan.ts
+++ b/apps/open-swe/src/nodes/interrupt-plan.ts
@@ -41,7 +41,7 @@ export async function interruptPlan(state: GraphState): Promise<Command> {
     throw new Error("No sandbox session ID found.");
   }
 
-  const userRequest = getUserRequest(state.messages);
+  const userRequest = getUserRequest(state.internalMessages);
 
   if (interruptRes.type === "accept") {
     const newSandboxSessionId = (await startSandbox(state.sandboxSessionId)).id;
diff --git a/apps/open-swe/src/nodes/open-pr.ts b/apps/open-swe/src/nodes/open-pr.ts
index 388cf4ea..2d5cf9f3 100644
--- a/apps/open-swe/src/nodes/open-pr.ts
+++ b/apps/open-swe/src/nodes/open-pr.ts
@@ -106,9 +106,10 @@ export async function openPullRequest(
   const model = await loadModel(config, Task.SUMMARIZER);
   const modelWithTool = model.bindTools([openPrTool], {
     tool_choice: openPrTool.name,
+    parallel_tool_calls: false,
   });
 
-  const userRequest = getUserRequest(state.messages);
+  const userRequest = getUserRequest(state.internalMessages);
   const response = await modelWithTool.invoke([
     {
       role: "user",
@@ -141,20 +142,23 @@ export async function openPullRequest(
     sandboxDeleted = await deleteSandbox(sandboxSessionId);
   }
 
+  const newMessages = [
+    response,
+    new ToolMessage({
+      tool_call_id: toolCall.id ?? "",
+      content: pr
+        ? `Created pull request: ${pr.html_url}`
+        : "Failed to create pull request.",
+      name: toolCall.name,
+      additional_kwargs: {
+        pull_request: pr,
+      },
+    }),
+  ];
+
   return {
-    messages: [
-      response,
-      new ToolMessage({
-        tool_call_id: toolCall.id ?? "",
-        content: pr
-          ? `Created pull request: ${pr.html_url}`
-          : "Failed to create pull request.",
-        name: toolCall.name,
-        additional_kwargs: {
-          pull_request: pr,
-        },
-      }),
-    ],
+    messages: newMessages,
+    internalMessages: newMessages,
     // If the sandbox was successfully deleted, we can remove it from the state.
     ...(sandboxDeleted && { sandboxSessionId: undefined }),
   };
diff --git a/apps/open-swe/src/nodes/progress-plan-step.ts b/apps/open-swe/src/nodes/progress-plan-step.ts
index 5002d139..5e247e45 100644
--- a/apps/open-swe/src/nodes/progress-plan-step.ts
+++ b/apps/open-swe/src/nodes/progress-plan-step.ts
@@ -73,14 +73,15 @@ export async function progressPlanStep(
   const model = await loadModel(config, Task.PROGRESS_PLAN_CHECKER);
   const modelWithTools = model.bindTools([setTaskStatusTool], {
     tool_choice: setTaskStatusTool.name,
+    parallel_tool_calls: false,
   });
 
-  const userRequest = getUserRequest(state.messages, {
+  const userRequest = getUserRequest(state.internalMessages, {
     returnFullMessage: true,
   });
   const conversationHistoryStr = `Here is the full conversation history after the user's request:
   
-${removeFirstHumanMessage(state.messages).map(getMessageString).join("\n")}
+${removeFirstHumanMessage(state.internalMessages).map(getMessageString).join("\n")}
 
 Take all of this information, and determine whether or not you have completed this task in the plan.
 Once you've determined the status of the current task, call the \`set_task_status\` tool.`;
@@ -118,6 +119,8 @@ Once you've determined the status of the current task, call the \`set_task_statu
     name: toolCall.name,
   });
 
+  const newMessages = [response, toolMessage];
+
   if (!isCompleted) {
     logger.info(
       "Current task has not been completed. Progressing to the next action.",
@@ -125,7 +128,10 @@ Once you've determined the status of the current task, call the \`set_task_statu
         reasoning: toolCall.args.reasoning,
       },
     );
-    const commandUpdate: GraphUpdate = { messages: [response, toolMessage] };
+    const commandUpdate: GraphUpdate = {
+      messages: newMessages,
+      internalMessages: newMessages,
+    };
     return new Command({
       goto: "generate-action",
       update: commandUpdate,
@@ -146,7 +152,8 @@ Once you've determined the status of the current task, call the \`set_task_statu
       "Found no remaining tasks in the plan during the check plan step. Continuing to the conclusion generation step.",
     );
     const commandUpdate: GraphUpdate = {
-      messages: [response, toolMessage],
+      messages: newMessages,
+      internalMessages: newMessages,
       // Even though there are no remaining tasks, still mark as completed so the UI reflects that the task is completed.
       plan: updatedPlanTasks,
     };
@@ -164,7 +171,8 @@ Once you've determined the status of the current task, call the \`set_task_statu
   });
 
   const commandUpdate: GraphUpdate = {
-    messages: [response, toolMessage],
+    messages: newMessages,
+    internalMessages: newMessages,
     plan: updatedPlanTasks,
   };
 
diff --git a/apps/open-swe/src/nodes/request-help.ts b/apps/open-swe/src/nodes/request-help.ts
index 5c396bd3..ee270e74 100644
--- a/apps/open-swe/src/nodes/request-help.ts
+++ b/apps/open-swe/src/nodes/request-help.ts
@@ -13,7 +13,7 @@ ${helpRequest}
 };
 
 export async function requestHelp(state: GraphState): Promise<Command> {
-  const lastMessage = state.messages[state.messages.length - 1];
+  const lastMessage = state.internalMessages[state.internalMessages.length - 1];
   if (!isAIMessage(lastMessage) || !lastMessage.tool_calls?.length) {
     throw new Error("Last message is not an AI message with tool calls.");
   }
@@ -53,14 +53,14 @@ export async function requestHelp(state: GraphState): Promise<Command> {
       throw new Error("Interrupt response expected to be a string.");
     }
     await startSandbox(sandboxSessionId);
+    const toolMessage = new ToolMessage({
+      tool_call_id: toolCall.id ?? "",
+      content: `Human response: ${interruptRes.args}`,
+      status: "success",
+    });
     const commandUpdate: GraphUpdate = {
-      messages: [
-        new ToolMessage({
-          tool_call_id: toolCall.id ?? "",
-          content: `Human response: ${interruptRes.args}`,
-          status: "success",
-        }),
-      ],
+      messages: [toolMessage],
+      internalMessages: [toolMessage],
     };
     return new Command({
       goto: "generate-action",
diff --git a/apps/open-swe/src/nodes/rewrite-plan.ts b/apps/open-swe/src/nodes/rewrite-plan.ts
index f3f70ad1..086288bf 100644
--- a/apps/open-swe/src/nodes/rewrite-plan.ts
+++ b/apps/open-swe/src/nodes/rewrite-plan.ts
@@ -134,10 +134,11 @@ async function identifyTasksToModifyFunc(
     {
       // The model should always call the tool when identifying plan changes.
       tool_choice: identifyPlanChangesTool.name,
+      parallel_tool_calls: false,
     },
   );
 
-  const userRequest = getUserRequest(state.messages);
+  const userRequest = getUserRequest(state.internalMessages);
   const response = await modelWithIdentifyChangesTool.invoke([
     {
       role: "user",
@@ -197,9 +198,10 @@ async function updatePlanTasksFunc(
   const modelWithUpdatePlanTasksTool = model.bindTools([updatePlanTasksTool], {
     // The model should always call the tool when identifying plan changes.
     tool_choice: updatePlanTasksTool.name,
+    parallel_tool_calls: false,
   });
 
-  const userRequest = getUserRequest(state.messages);
+  const userRequest = getUserRequest(state.internalMessages);
   const response = await modelWithUpdatePlanTasksTool.invoke([
     {
       role: "user",
diff --git a/apps/open-swe/src/nodes/summarize-task-steps.ts b/apps/open-swe/src/nodes/summarize-task-steps.ts
index 9f8fc8e3..798a56ed 100644
--- a/apps/open-swe/src/nodes/summarize-task-steps.ts
+++ b/apps/open-swe/src/nodes/summarize-task-steps.ts
@@ -107,7 +107,7 @@ async function generateTaskSummaryFunc(
     },
     {
       role: "user",
-      content: formatUserMessage(state.messages, activePlanItems),
+      content: formatUserMessage(state.internalMessages, activePlanItems),
     },
   ]);
 
@@ -140,7 +140,7 @@ export async function summarizeTaskSteps(
     taskSummary.summary,
   );
 
-  const removedMessages = removeLastTaskMessages(state.messages);
+  const removedMessages = removeLastTaskMessages(state.internalMessages);
   logger.info(`Removing ${removedMessages.length} message(s) from state.`);
 
   const condensedTaskMessage = new AIMessage({
@@ -155,7 +155,8 @@ export async function summarizeTaskSteps(
   const allTasksCompleted = activePlanItems.every((p) => p.completed);
   if (allTasksCompleted) {
     const commandUpdate: GraphUpdate = {
-      messages: newMessagesStateUpdate,
+      messages: [condensedTaskMessage],
+      internalMessages: newMessagesStateUpdate,
       plan: updatedTaskPlan,
     };
     return new Command({
@@ -165,7 +166,8 @@ export async function summarizeTaskSteps(
   }
 
   const commandUpdate: GraphUpdate = {
-    messages: newMessagesStateUpdate,
+    messages: [condensedTaskMessage],
+    internalMessages: newMessagesStateUpdate,
     plan: updatedTaskPlan,
   };
   return new Command({
diff --git a/apps/open-swe/src/nodes/take-action.ts b/apps/open-swe/src/nodes/take-action.ts
index 1b63d91f..e7eba9ab 100644
--- a/apps/open-swe/src/nodes/take-action.ts
+++ b/apps/open-swe/src/nodes/take-action.ts
@@ -47,7 +47,7 @@ export async function takeAction(
   state: GraphState,
   config: GraphConfig,
 ): Promise<Command> {
-  const lastMessage = state.messages[state.messages.length - 1];
+  const lastMessage = state.internalMessages[state.internalMessages.length - 1];
 
   if (!isAIMessage(lastMessage) || !lastMessage.tool_calls?.length) {
     throw new Error("Last message is not an AI message with tool calls.");
@@ -68,17 +68,17 @@ export async function takeAction(
 
   if (!tool) {
     logger.error(`Unknown tool: ${toolCall.name}`);
+    const toolMessage = new ToolMessage({
+      tool_call_id: toolCall.id ?? "",
+      content: `Unknown tool: ${toolCall.name}`,
+      name: toolCall.name,
+      status: "error",
+    });
     return new Command({
       goto: "progress-plan-step",
       update: {
-        messages: [
-          new ToolMessage({
-            tool_call_id: toolCall.id ?? "",
-            content: `Unknown tool: ${toolCall.name}`,
-            name: toolCall.name,
-            status: "error",
-          }),
-        ],
+        messages: [toolMessage],
+        internalMessages: [toolMessage],
       },
     });
   }
@@ -150,7 +150,7 @@ export async function takeAction(
   }
 
   const shouldRouteDiagnoseNode = shouldDiagnoseError(
-    [...state.messages, toolMessage].filter(
+    [...state.internalMessages, toolMessage].filter(
       (m): m is ToolMessage =>
         isToolMessage(m) && !m.additional_kwargs?.is_diagnosis,
     ),
@@ -162,6 +162,7 @@ export async function takeAction(
     goto: shouldRouteDiagnoseNode ? "diagnose-error" : "progress-plan-step",
     update: {
       messages: [toolMessage],
+      internalMessages: [toolMessage],
       ...(branchName && { branchName }),
       codebaseTree,
     },
diff --git a/apps/open-swe/src/nodes/update-plan.ts b/apps/open-swe/src/nodes/update-plan.ts
index 42f25c85..80269df7 100644
--- a/apps/open-swe/src/nodes/update-plan.ts
+++ b/apps/open-swe/src/nodes/update-plan.ts
@@ -88,7 +88,7 @@ export async function updatePlan(
   if (!state.planChangeRequest) {
     throw new Error("No plan change request found.");
   }
-  const lastMessage = state.messages[state.messages.length - 1];
+  const lastMessage = state.internalMessages[state.internalMessages.length - 1];
   if (
     !lastMessage ||
     !isAIMessage(lastMessage) ||
@@ -108,6 +108,7 @@ export async function updatePlan(
   const model = await loadModel(config, Task.PLANNER);
   const modelWithTools = model.bindTools([updatePlanTool], {
     tool_choice: updatePlanTool.name,
+    parallel_tool_calls: false,
   });
 
   const activeTask = getActiveTask(state.plan);
@@ -124,7 +125,7 @@ export async function updatePlan(
     state.planChangeRequest,
     activePlanItems,
   );
-  const userMessage = formatUserMessage(state.messages);
+  const userMessage = formatUserMessage(state.internalMessages);
 
   const response = await modelWithTools.invoke([
     {
@@ -160,21 +161,21 @@ export async function updatePlan(
     newPlanItems,
     "agent",
   );
+  const toolMessage = new ToolMessage({
+    tool_call_id: updatePlanToolCallId,
+    content:
+      "Successfully updated the plan. The complete updated plan items are as follow:\n\n" +
+      newPlanItems
+        .map(
+          (p) =>
+            `<plan-item completed="${p.completed}" index="${p.index}">${p.plan}</plan-item>`,
+        )
+        .join("\n"),
+  });
 
   return {
-    messages: [
-      new ToolMessage({
-        tool_call_id: updatePlanToolCallId,
-        content:
-          "Successfully updated the plan. The complete updated plan items are as follow:\n\n" +
-          newPlanItems
-            .map(
-              (p) =>
-                `<plan-item completed="${p.completed}" index="${p.index}">${p.plan}</plan-item>`,
-            )
-            .join("\n"),
-      }),
-    ],
+    messages: [toolMessage],
+    internalMessages: [toolMessage],
     plan: newTaskPlan,
     planChangeRequest: null,
   };
diff --git a/apps/open-swe/src/subgraphs/planner/nodes/generate-message.ts b/apps/open-swe/src/subgraphs/planner/nodes/generate-message.ts
index 9e1ad72f..d11b979d 100644
--- a/apps/open-swe/src/subgraphs/planner/nodes/generate-message.ts
+++ b/apps/open-swe/src/subgraphs/planner/nodes/generate-message.ts
@@ -37,7 +37,7 @@ The user's request is the first user message in the conversation below. Ensure y
 
 function formatSystemPrompt(state: PlannerGraphState): string {
   // It's a followup if there's more than one human message.
-  const isFollowup = state.messages.filter(isHumanMessage).length > 1;
+  const isFollowup = state.internalMessages.filter(isHumanMessage).length > 1;
 
   return systemPrompt
     .replace(
@@ -58,11 +58,15 @@ export async function generateAction(
 ): Promise<PlannerGraphUpdate> {
   const model = await loadModel(config, Task.ACTION_GENERATOR);
   const tools = [shellTool];
-  const modelWithTools = model.bindTools(tools, { tool_choice: "auto" });
+  const modelWithTools = model.bindTools(tools, {
+    tool_choice: "auto",
+    parallel_tool_calls: false,
+  });
 
-  const userRequest = getUserRequest(state.messages, {
+  const userRequest = getUserRequest(state.internalMessages, {
     returnFullMessage: true,
   });
+
   const response = await modelWithTools
     .withConfig({ tags: ["nostream"] })
     .invoke([
@@ -85,6 +89,7 @@ export async function generateAction(
   });
 
   return {
+    messages: [response],
     plannerMessages: [response],
   };
 }
diff --git a/apps/open-swe/src/subgraphs/planner/nodes/generate-plan.ts b/apps/open-swe/src/subgraphs/planner/nodes/generate-plan.ts
index 6be84cb5..6ba150c8 100644
--- a/apps/open-swe/src/subgraphs/planner/nodes/generate-plan.ts
+++ b/apps/open-swe/src/subgraphs/planner/nodes/generate-plan.ts
@@ -36,8 +36,8 @@ The user's request is as follows. Ensure you generate your plan in accordance wi
 
 function formatSystemPrompt(state: PlannerGraphState): string {
   // It's a followup if there's more than one human message.
-  const isFollowup = state.messages.filter(isHumanMessage).length > 1;
-  const userRequest = getUserRequest(state.messages);
+  const isFollowup = state.internalMessages.filter(isHumanMessage).length > 1;
+  const userRequest = getUserRequest(state.internalMessages);
 
   return systemPrompt
     .replace(
@@ -54,6 +54,7 @@ export async function generatePlan(
   const model = await loadModel(config, Task.PLANNER);
   const modelWithTools = model.bindTools([sessionPlanTool], {
     tool_choice: sessionPlanTool.name,
+    parallel_tool_calls: false,
   });
 
   let optionalToolMessage: ToolMessage | undefined;
@@ -89,6 +90,7 @@ export async function generatePlan(
   }
 
   return {
+    messages: [response],
     proposedPlan: response.tool_calls[0].args.plan,
     ...(newSessionId && { sandboxSessionId: newSessionId }),
     // Do this so that the planner state is up to date with the tool call.
diff --git a/apps/open-swe/src/subgraphs/planner/nodes/summarizer.ts b/apps/open-swe/src/subgraphs/planner/nodes/summarizer.ts
index 8a85fb01..9f0bc991 100644
--- a/apps/open-swe/src/subgraphs/planner/nodes/summarizer.ts
+++ b/apps/open-swe/src/subgraphs/planner/nodes/summarizer.ts
@@ -48,9 +48,10 @@ export async function summarizer(
   const model = await loadModel(config, Task.SUMMARIZER);
   const modelWithTools = model.bindTools([condenseContextTool], {
     tool_choice: condenseContextTool.name,
+    parallel_tool_calls: false,
   });
 
-  const userRequest = getUserRequest(state.messages);
+  const userRequest = getUserRequest(state.internalMessages);
   const conversationHistoryStr = `Here is the full conversation history:
 
 ${state.plannerMessages.map(getMessageString).join("\n")}`;
@@ -72,6 +73,7 @@ ${state.plannerMessages.map(getMessageString).join("\n")}`;
   }
 
   return {
+    messages: [response],
     planContextSummary: toolCall.args.context,
   };
 }
diff --git a/apps/open-swe/src/subgraphs/planner/nodes/take-action.ts b/apps/open-swe/src/subgraphs/planner/nodes/take-action.ts
index 0d2c41f5..a4fd3491 100644
--- a/apps/open-swe/src/subgraphs/planner/nodes/take-action.ts
+++ b/apps/open-swe/src/subgraphs/planner/nodes/take-action.ts
@@ -34,18 +34,22 @@ export async function takeAction(
 
   if (!tool) {
     logger.error(`Unknown tool: ${toolCall.name}`);
+    const toolMessage = new ToolMessage({
+      tool_call_id: toolCall.id ?? "",
+      content: `Unknown tool: ${toolCall.name}`,
+      name: toolCall.name,
+      status: "error",
+    });
     return {
-      plannerMessages: [
-        new ToolMessage({
-          tool_call_id: toolCall.id ?? "",
-          content: `Unknown tool: ${toolCall.name}`,
-          name: toolCall.name,
-          status: "error",
-        }),
-      ],
+      messages: [toolMessage],
+      plannerMessages: [toolMessage],
     };
   }
 
+  logger.info("Executing planner tool action", {
+    ...toolCall,
+  });
+
   let result = "";
   let toolCallStatus: "success" | "error" = "success";
   try {
@@ -86,7 +90,13 @@ export async function takeAction(
     status: toolCallStatus,
   });
 
+  logger.info("Completed planner tool action", {
+    tool_call_id: toolCall.id,
+    status: toolCallStatus,
+  });
+
   return {
+    messages: [toolMessage],
     plannerMessages: [toolMessage],
   };
 }
diff --git a/apps/open-swe/src/subgraphs/planner/types.ts b/apps/open-swe/src/subgraphs/planner/types.ts
index 051a4fc6..8c9532ab 100644
--- a/apps/open-swe/src/subgraphs/planner/types.ts
+++ b/apps/open-swe/src/subgraphs/planner/types.ts
@@ -1,14 +1,24 @@
 import "@langchain/langgraph/zod";
 import { z } from "zod";
-import { addMessages, Messages } from "@langchain/langgraph";
+import { Messages, messagesStateReducer } from "@langchain/langgraph";
 import { BaseMessage } from "@langchain/core/messages";
 import { GraphAnnotation } from "@open-swe/shared/open-swe/types";
+import { withLangGraph } from "@langchain/langgraph/zod";
 
 export const PlannerGraphStateObj = GraphAnnotation.extend({
-  plannerMessages: z
-    .custom<BaseMessage[]>()
-    .default(() => [])
-    .langgraph.reducer<Messages>((state, update) => addMessages(state, update)),
+  plannerMessages: withLangGraph<BaseMessage[], Messages>(
+    z.custom<BaseMessage[]>(),
+    {
+      reducer: {
+        schema: z.custom<Messages>(),
+        fn: messagesStateReducer,
+      },
+      jsonSchemaExtra: {
+        langgraph_type: "messages",
+      },
+      default: () => [],
+    },
+  ),
 });
 
 export type PlannerGraphState = z.infer<typeof PlannerGraphStateObj>;
diff --git a/apps/web/src/components/thread/index.tsx b/apps/web/src/components/thread/index.tsx
index fe229d88..6a17fe80 100644
--- a/apps/web/src/components/thread/index.tsx
+++ b/apps/web/src/components/thread/index.tsx
@@ -246,12 +246,14 @@ export function Thread() {
     const context =
       Object.keys(artifactContext).length > 0 ? artifactContext : undefined;
 
+    const newMessages = [
+      ...toolMessages,
+      newHumanMessage,
+    ] as unknown as BaseMessage[];
     stream.submit(
       {
-        messages: [
-          ...toolMessages,
-          newHumanMessage,
-        ] as unknown as BaseMessage[],
+        messages: newMessages,
+        internalMessages: newMessages,
         context,
         targetRepository: selectedRepository,
       },
diff --git a/apps/web/src/components/thread/messages/human.tsx b/apps/web/src/components/thread/messages/human.tsx
index ce7c329f..81803607 100644
--- a/apps/web/src/components/thread/messages/human.tsx
+++ b/apps/web/src/components/thread/messages/human.tsx
@@ -53,9 +53,12 @@ export function HumanMessage({
   const handleSubmitEdit = () => {
     setIsEditing(false);
 
-    const newMessage: Message = { type: "human", content: value };
+    const newMessage = {
+      type: "human",
+      content: value,
+    } as unknown as BaseMessage;
     thread.submit(
-      { messages: [newMessage] as unknown as BaseMessage[] },
+      { messages: [newMessage], internalMessages: [newMessage] },
       {
         checkpoint: parentCheckpoint,
         streamMode: ["values"],
diff --git a/packages/shared/src/open-swe/types.ts b/packages/shared/src/open-swe/types.ts
index 8f54fa0a..d1b86781 100644
--- a/packages/shared/src/open-swe/types.ts
+++ b/packages/shared/src/open-swe/types.ts
@@ -2,6 +2,8 @@ import "@langchain/langgraph/zod";
 import { z } from "zod";
 import {
   LangGraphRunnableConfig,
+  Messages,
+  messagesStateReducer,
   MessagesZodState,
 } from "@langchain/langgraph/web";
 import { MODEL_OPTIONS, MODEL_OPTIONS_NO_THINKING } from "./models.js";
@@ -12,6 +14,8 @@ import {
   type RemoveUIMessage,
 } from "@langchain/langgraph-sdk/react-ui";
 import { GITHUB_TOKEN_COOKIE } from "../constants.js";
+import { withLangGraph } from "@langchain/langgraph/zod";
+import { BaseMessage } from "@langchain/core/messages";
 
 export type PlanItem = {
   /**
@@ -116,6 +120,24 @@ export type TargetRepository = {
 };
 
 export const GraphAnnotation = MessagesZodState.extend({
+  /**
+   * The internal messages. These are the messages which are
+   * passed to the LLM, truncated, removed etc. The main `messages`
+   * key is never modified to persist the content show on the client.
+   */
+  internalMessages: withLangGraph<BaseMessage[], Messages>(
+    z.custom<BaseMessage[]>(),
+    {
+      reducer: {
+        schema: z.custom<Messages>(),
+        fn: messagesStateReducer,
+      },
+      jsonSchemaExtra: {
+        langgraph_type: "messages",
+      },
+      default: () => [],
+    },
+  ),
   proposedPlan: z
     .array(z.string())
     .default(() => [])