diff --git a/src/app/projects/[projectId]/components/chatForm/ChatInput.tsx b/src/app/projects/[projectId]/components/chatForm/ChatInput.tsx
new file mode 100644
index 0000000..3e8c37c
--- /dev/null
+++ b/src/app/projects/[projectId]/components/chatForm/ChatInput.tsx
@@ -0,0 +1,146 @@
+import { AlertCircleIcon, LoaderIcon, SendIcon } from "lucide-react";
+import { type FC, useId, useRef, useState } from "react";
+import { Button } from "../../../../../components/ui/button";
+import { Textarea } from "../../../../../components/ui/textarea";
+import {
+  CommandCompletion,
+  type CommandCompletionRef,
+} from "./CommandCompletion";
+import { FileCompletion, type FileCompletionRef } from "./FileCompletion";
+
+export interface ChatInputProps {
+  projectId: string;
+  onSubmit: (message: string) => void;
+  isPending: boolean;
+  error?: Error | null;
+  placeholder: string;
+  buttonText: string;
+  minHeight?: string;
+  containerClassName?: string;
+  disabled?: boolean;
+  buttonSize?: "sm" | "default" | "lg";
+}
+
+export const ChatInput: FC<ChatInputProps> = ({
+  projectId,
+  onSubmit,
+  isPending,
+  error,
+  placeholder,
+  buttonText,
+  minHeight = "min-h-[100px]",
+  containerClassName = "",
+  disabled = false,
+  buttonSize = "lg",
+}) => {
+  const textareaRef = useRef<HTMLTextAreaElement>(null);
+  const [message, setMessage] = useState("");
+  const commandCompletionRef = useRef<CommandCompletionRef>(null);
+  const fileCompletionRef = useRef<FileCompletionRef>(null);
+  const helpId = useId();
+
+  const handleSubmit = () => {
+    if (!message.trim()) return;
+    onSubmit(message.trim());
+    setMessage("");
+  };
+
+  const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
+    if (fileCompletionRef.current?.handleKeyDown(e)) {
+      return;
+    }
+
+    if (commandCompletionRef.current?.handleKeyDown(e)) {
+      return;
+    }
+
+    if (e.key === "Enter" && e.shiftKey) {
+      e.preventDefault();
+      handleSubmit();
+    }
+  };
+
+  const handleCommandSelect = (command: string) => {
+    setMessage(command);
+    textareaRef.current?.focus();
+  };
+
+  const handleFileSelect = (filePath: string) => {
+    setMessage(filePath);
+    textareaRef.current?.focus();
+  };
+
+  return (
+    <div className={containerClassName}>
+      {error && (
+        <div className="flex items-center gap-2 p-3 text-sm text-destructive bg-destructive/10 border border-destructive/20 rounded-md mb-4">
+          <AlertCircleIcon className="w-4 h-4" />
+          <span>Failed to send message. Please try again.</span>
+        </div>
+      )}
+
+      <div className="space-y-3">
+        <div className="relative">
+          <Textarea
+            ref={textareaRef}
+            value={message}
+            onChange={(e) => setMessage(e.target.value)}
+            onKeyDown={handleKeyDown}
+            placeholder={placeholder}
+            className={`${minHeight} resize-none`}
+            disabled={isPending || disabled}
+            maxLength={4000}
+            aria-label="Message input with completion support"
+            aria-describedby={helpId}
+            aria-expanded={message.startsWith("/") || message.includes("@")}
+            aria-haspopup="listbox"
+            role="combobox"
+            aria-autocomplete="list"
+          />
+          <CommandCompletion
+            ref={commandCompletionRef}
+            projectId={projectId}
+            inputValue={message}
+            onCommandSelect={handleCommandSelect}
+            className="absolute top-full left-0 right-0"
+          />
+          {
+            <FileCompletion
+              ref={fileCompletionRef}
+              projectId={projectId}
+              inputValue={message}
+              onFileSelect={handleFileSelect}
+              className="absolute top-full left-0 right-0"
+            />
+          }
+        </div>
+
+        <div className="flex items-center justify-between">
+          <span className="text-xs text-muted-foreground" id={helpId}>
+            {message.length}/4000 characters " • Use arrow keys to navigate
+            completions"
+          </span>
+
+          <Button
+            onClick={handleSubmit}
+            disabled={!message.trim() || isPending || disabled}
+            size={buttonSize}
+            className="gap-2"
+          >
+            {isPending ? (
+              <>
+                <LoaderIcon className="w-4 h-4 animate-spin" />
+                Sending... This may take a while.
+              </>
+            ) : (
+              <>
+                <SendIcon className="w-4 h-4" />
+                {buttonText}
+              </>
+            )}
+          </Button>
+        </div>
+      </div>
+    </div>
+  );
+};
diff --git a/src/app/projects/[projectId]/components/newChat/CommandCompletion.tsx b/src/app/projects/[projectId]/components/chatForm/CommandCompletion.tsx
similarity index 100%
rename from src/app/projects/[projectId]/components/newChat/CommandCompletion.tsx
rename to src/app/projects/[projectId]/components/chatForm/CommandCompletion.tsx
diff --git a/src/app/projects/[projectId]/components/newChat/FileCompletion.tsx b/src/app/projects/[projectId]/components/chatForm/FileCompletion.tsx
similarity index 96%
rename from src/app/projects/[projectId]/components/newChat/FileCompletion.tsx
rename to src/app/projects/[projectId]/components/chatForm/FileCompletion.tsx
index b82e924..31e5e60 100644
--- a/src/app/projects/[projectId]/components/newChat/FileCompletion.tsx
+++ b/src/app/projects/[projectId]/components/chatForm/FileCompletion.tsx
@@ -128,13 +128,15 @@ export const FileCompletion = forwardRef<
       const fullPath = entry.path;
 
       // For directories, add a trailing slash to continue completion (unless forced to close)
-      const pathToInsert =
-        entry.type === "directory" && !forceClose ? `${fullPath}/` : fullPath;
+      // For files or when forced to close, add a space to end completion
 
       // Reconstruct the message with the selected path
-      const newMessage = `${beforeAt}@${pathToInsert}${afterAt.split(/\s/).slice(1).join(" ")}`;
+      const remainingText = afterAt.split(/\s/).slice(1).join(" ");
+      const newMessage =
+        `${beforeAt}@${fullPath}${remainingText}`.trim() +
+        (entry.type === "directory" && !forceClose ? "/" : " ");
 
-      onFileSelect(newMessage.trim());
+      onFileSelect(newMessage);
 
       // Close completion if it's a file, or if forced to close
       if (entry.type === "file" || forceClose) {
diff --git a/src/app/projects/[projectId]/components/chatForm/index.ts b/src/app/projects/[projectId]/components/chatForm/index.ts
new file mode 100644
index 0000000..1b68d06
--- /dev/null
+++ b/src/app/projects/[projectId]/components/chatForm/index.ts
@@ -0,0 +1,7 @@
+export type { ChatInputProps } from "./ChatInput";
+export { ChatInput } from "./ChatInput";
+export type { CommandCompletionRef } from "./CommandCompletion";
+export { CommandCompletion } from "./CommandCompletion";
+export type { FileCompletionRef } from "./FileCompletion";
+export { FileCompletion } from "./FileCompletion";
+export { useNewChatMutation, useResumeChatMutation } from "./useChatMutations";
diff --git a/src/app/projects/[projectId]/components/chatForm/useChatMutations.ts b/src/app/projects/[projectId]/components/chatForm/useChatMutations.ts
new file mode 100644
index 0000000..463aec7
--- /dev/null
+++ b/src/app/projects/[projectId]/components/chatForm/useChatMutations.ts
@@ -0,0 +1,75 @@
+import { useMutation } from "@tanstack/react-query";
+import { useRouter } from "next/navigation";
+import { honoClient } from "../../../../../lib/api/client";
+
+export const useNewChatMutation = (
+  projectId: string,
+  onSuccess?: () => void,
+) => {
+  const router = useRouter();
+
+  return useMutation({
+    mutationFn: async (options: { message: string }) => {
+      const response = await honoClient.api.projects[":projectId"][
+        "new-session"
+      ].$post(
+        {
+          param: { projectId },
+          json: { message: options.message },
+        },
+        {
+          init: {
+            signal: AbortSignal.timeout(10 * 1000),
+          },
+        },
+      );
+
+      if (!response.ok) {
+        throw new Error(response.statusText);
+      }
+
+      return response.json();
+    },
+    onSuccess: async (response) => {
+      onSuccess?.();
+      router.push(
+        `/projects/${projectId}/sessions/${response.sessionId}#message-${response.userMessageId}`,
+      );
+    },
+  });
+};
+
+export const useResumeChatMutation = (projectId: string, sessionId: string) => {
+  const router = useRouter();
+
+  return useMutation({
+    mutationFn: async (options: { message: string }) => {
+      const response = await honoClient.api.projects[":projectId"].sessions[
+        ":sessionId"
+      ].resume.$post(
+        {
+          param: { projectId, sessionId },
+          json: { resumeMessage: options.message },
+        },
+        {
+          init: {
+            signal: AbortSignal.timeout(10 * 1000),
+          },
+        },
+      );
+
+      if (!response.ok) {
+        throw new Error(response.statusText);
+      }
+
+      return response.json();
+    },
+    onSuccess: async (response) => {
+      if (sessionId !== response.sessionId) {
+        router.push(
+          `/projects/${projectId}/sessions/${response.sessionId}#message-${response.userMessageId}`,
+        );
+      }
+    },
+  });
+};
diff --git a/src/app/projects/[projectId]/components/newChat/NewChat.tsx b/src/app/projects/[projectId]/components/newChat/NewChat.tsx
index a8cd98b..87cc345 100644
--- a/src/app/projects/[projectId]/components/newChat/NewChat.tsx
+++ b/src/app/projects/[projectId]/components/newChat/NewChat.tsx
@@ -1,162 +1,26 @@
-import { useMutation } from "@tanstack/react-query";
-import { AlertCircleIcon, LoaderIcon, SendIcon } from "lucide-react";
-import { useRouter } from "next/navigation";
-import { type FC, useId, useRef, useState } from "react";
-import { Button } from "../../../../../components/ui/button";
-import { Textarea } from "../../../../../components/ui/textarea";
-import { honoClient } from "../../../../../lib/api/client";
-import {
-  CommandCompletion,
-  type CommandCompletionRef,
-} from "./CommandCompletion";
-import { FileCompletion, type FileCompletionRef } from "./FileCompletion";
+import type { FC } from "react";
+import { ChatInput, useNewChatMutation } from "../chatForm";
 
 export const NewChat: FC<{
   projectId: string;
   onSuccess?: () => void;
 }> = ({ projectId, onSuccess }) => {
-  const router = useRouter();
-  const textareaRef = useRef<HTMLTextAreaElement>(null);
+  const startNewChat = useNewChatMutation(projectId, onSuccess);
 
-  const startNewChat = useMutation({
-    mutationFn: async (options: { message: string }) => {
-      const response = await honoClient.api.projects[":projectId"][
-        "new-session"
-      ].$post(
-        {
-          param: { projectId },
-          json: { message: options.message },
-        },
-        {
-          init: {
-            signal: AbortSignal.timeout(10 * 1000),
-          },
-        },
-      );
-
-      if (!response.ok) {
-        throw new Error(response.statusText);
-      }
-
-      return response.json();
-    },
-    onSuccess: async (response) => {
-      setMessage("");
-      onSuccess?.();
-
-      router.push(
-        `/projects/${projectId}/sessions/${response.sessionId}#message-${response.userMessageId}`,
-      );
-    },
-  });
-
-  const [message, setMessage] = useState("");
-  const completionRef = useRef<CommandCompletionRef>(null);
-  const fileCompletionRef = useRef<FileCompletionRef>(null);
-  const helpId = useId();
-
-  const handleSubmit = () => {
-    if (!message.trim()) return;
-    startNewChat.mutate({ message: message.trim() });
-  };
-
-  const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
-    // まずファイル補完のキーボードイベントを処理
-    if (fileCompletionRef.current?.handleKeyDown(e)) {
-      return;
-    }
-
-    // 次にコマンド補完のキーボードイベントを処理
-    if (completionRef.current?.handleKeyDown(e)) {
-      return;
-    }
-
-    // 通常のキーボードイベント処理
-    if (e.key === "Enter" && e.shiftKey) {
-      e.preventDefault();
-      handleSubmit();
-    }
-  };
-
-  const handleCommandSelect = (command: string) => {
-    setMessage(command);
-    textareaRef.current?.focus();
-  };
-
-  const handleFileSelect = (filePath: string) => {
-    setMessage(filePath);
-    textareaRef.current?.focus();
+  const handleSubmit = (message: string) => {
+    startNewChat.mutate({ message });
   };
 
   return (
-    <div className="space-y-4">
-      {startNewChat.error && (
-        <div className="flex items-center gap-2 p-3 text-sm text-destructive bg-destructive/10 border border-destructive/20 rounded-md">
-          <AlertCircleIcon className="w-4 h-4" />
-          <span>Failed to start new chat. Please try again.</span>
-        </div>
-      )}
-
-      <div className="space-y-3">
-        <div className="relative">
-          <Textarea
-            ref={textareaRef}
-            value={message}
-            onChange={(e) => setMessage(e.target.value)}
-            onKeyDown={handleKeyDown}
-            placeholder="Type your message here... (Start with / for commands, @ for files, Shift+Enter to send)"
-            className="min-h-[100px] resize-none"
-            disabled={startNewChat.isPending}
-            maxLength={4000}
-            aria-label="Message input with command completion"
-            aria-describedby={helpId}
-            aria-expanded={message.startsWith("/") || message.includes("@")}
-            aria-haspopup="listbox"
-            role="combobox"
-            aria-autocomplete="list"
-          />
-          <CommandCompletion
-            ref={completionRef}
-            projectId={projectId}
-            inputValue={message}
-            onCommandSelect={handleCommandSelect}
-            className="absolute top-full left-0 right-0"
-          />
-          <FileCompletion
-            ref={fileCompletionRef}
-            projectId={projectId}
-            inputValue={message}
-            onFileSelect={handleFileSelect}
-            className="absolute top-full left-0 right-0"
-          />
-        </div>
-
-        <div className="flex items-center justify-between">
-          <span className="text-xs text-muted-foreground" id={helpId}>
-            {message.length}/4000 characters • Use arrow keys to navigate
-            completions
-          </span>
-
-          <Button
-            onClick={handleSubmit}
-            disabled={!message.trim() || startNewChat.isPending}
-            size="lg"
-            className="gap-2"
-          >
-            {startNewChat.isPending ? (
-              <>
-                <LoaderIcon className="w-4 h-4 animate-spin" />
-                Sending... This may take a while.
-              </>
-            ) : (
-              <>
-                <SendIcon className="w-4 h-4" />
-                Start Chat
-              </>
-            )}
-          </Button>
-        </div>
-      </div>
-    </div>
+    <ChatInput
+      projectId={projectId}
+      onSubmit={handleSubmit}
+      isPending={startNewChat.isPending}
+      error={startNewChat.error}
+      placeholder="Type your message here... (Start with / for commands, @ for files, Shift+Enter to send)"
+      buttonText="Start Chat"
+      minHeight="min-h-[100px]"
+      containerClassName="space-y-4"
+    />
   );
 };
diff --git a/src/app/projects/[projectId]/sessions/[sessionId]/components/resumeChat/ResumeChat.tsx b/src/app/projects/[projectId]/sessions/[sessionId]/components/resumeChat/ResumeChat.tsx
index 485c46e..5dad2f3 100644
--- a/src/app/projects/[projectId]/sessions/[sessionId]/components/resumeChat/ResumeChat.tsx
+++ b/src/app/projects/[projectId]/sessions/[sessionId]/components/resumeChat/ResumeChat.tsx
@@ -1,15 +1,8 @@
-import { useMutation } from "@tanstack/react-query";
-import { AlertCircleIcon, LoaderIcon, SendIcon } from "lucide-react";
-import { useRouter } from "next/navigation";
-import { type FC, useId, useRef, useState } from "react";
-
-import { Button } from "../../../../../../../components/ui/button";
-import { Textarea } from "../../../../../../../components/ui/textarea";
-import { honoClient } from "../../../../../../../lib/api/client";
+import type { FC } from "react";
 import {
-  CommandCompletion,
-  type CommandCompletionRef,
-} from "../../../../components/newChat/CommandCompletion";
+  ChatInput,
+  useResumeChatMutation,
+} from "../../../../components/chatForm";
 
 export const ResumeChat: FC<{
   projectId: string;
@@ -17,135 +10,32 @@ export const ResumeChat: FC<{
   isPausedTask: boolean;
   isRunningTask: boolean;
 }> = ({ projectId, sessionId, isPausedTask, isRunningTask }) => {
-  const router = useRouter();
-  const textareaRef = useRef<HTMLTextAreaElement>(null);
+  const resumeChat = useResumeChatMutation(projectId, sessionId);
 
-  const resumeChat = useMutation({
-    mutationFn: async (options: { message: string }) => {
-      const response = await honoClient.api.projects[":projectId"].sessions[
-        ":sessionId"
-      ].resume.$post(
-        {
-          param: { projectId, sessionId },
-          json: { resumeMessage: options.message },
-        },
-        {
-          init: {
-            signal: AbortSignal.timeout(10 * 1000),
-          },
-        },
-      );
-
-      if (!response.ok) {
-        throw new Error(response.statusText);
-      }
-
-      return response.json();
-    },
-    onSuccess: async (response) => {
-      if (sessionId !== response.sessionId) {
-        router.push(
-          `/projects/${projectId}/sessions/${response.sessionId}#message-${response.userMessageId}`,
-        );
-      }
-
-      setMessage("");
-    },
-  });
-
-  const [message, setMessage] = useState("");
-  const completionRef = useRef<CommandCompletionRef>(null);
-  const helpId = useId();
-
-  const handleSubmit = () => {
-    if (!message.trim()) return;
-    resumeChat.mutate({ message: message.trim() });
+  const handleSubmit = (message: string) => {
+    resumeChat.mutate({ message });
   };
 
-  const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
-    // まずコマンド補完のキーボードイベントを処理
-    if (completionRef.current?.handleKeyDown(e)) {
-      return;
+  const getButtonText = () => {
+    if (isPausedTask || isRunningTask) {
+      return "Send";
     }
-
-    // 通常のキーボードイベント処理
-    if (e.key === "Enter" && e.shiftKey) {
-      e.preventDefault();
-      handleSubmit();
-    }
-  };
-
-  const handleCommandSelect = (command: string) => {
-    setMessage(command);
-    textareaRef.current?.focus();
+    return "Resume";
   };
 
   return (
     <div className="border-t border-border/50 bg-muted/20 p-4 mt-6">
-      {resumeChat.error && (
-        <div className="flex items-center gap-2 p-3 mb-3 text-sm text-destructive bg-destructive/10 border border-destructive/20 rounded-md">
-          <AlertCircleIcon className="w-4 h-4" />
-          <span>Failed to resume chat. Please try again.</span>
-        </div>
-      )}
-
-      <div className="space-y-2">
-        <div className="relative">
-          <Textarea
-            ref={textareaRef}
-            value={message}
-            onChange={(e) => setMessage(e.target.value)}
-            onKeyDown={handleKeyDown}
-            placeholder="Type your message... (Start with / for commands, Shift+Enter to send)"
-            className="min-h-[60px] resize-none"
-            disabled={resumeChat.isPending}
-            maxLength={4000}
-            aria-label="Message input with command completion"
-            aria-describedby={helpId}
-            aria-expanded={message.startsWith("/")}
-            aria-haspopup="listbox"
-            role="combobox"
-            aria-autocomplete="list"
-          />
-          <CommandCompletion
-            ref={completionRef}
-            projectId={projectId}
-            inputValue={message}
-            onCommandSelect={handleCommandSelect}
-            className="absolute top-full left-0 right-0"
-          />
-        </div>
-
-        <div className="flex items-center justify-between">
-          <span className="text-xs text-muted-foreground" id={helpId}>
-            {message.length}/4000
-          </span>
-
-          <Button
-            onClick={handleSubmit}
-            disabled={!message.trim() || resumeChat.isPending}
-            size="default"
-            className="gap-2"
-          >
-            {resumeChat.isPending ? (
-              <>
-                <LoaderIcon className="w-4 h-4 animate-spin" />
-                Sending... This may take a while.
-              </>
-            ) : isPausedTask || isRunningTask ? (
-              <>
-                <SendIcon className="w-4 h-4" />
-                Send
-              </>
-            ) : (
-              <>
-                <SendIcon className="w-4 h-4" />
-                Resume
-              </>
-            )}
-          </Button>
-        </div>
-      </div>
+      <ChatInput
+        projectId={projectId}
+        onSubmit={handleSubmit}
+        isPending={resumeChat.isPending}
+        error={resumeChat.error}
+        placeholder="Type your message... (Start with / for commands, Shift+Enter to send)"
+        buttonText={getButtonText()}
+        minHeight="min-h-[60px]"
+        containerClassName="space-y-2"
+        buttonSize="default"
+      />
     </div>
   );
 };