{"meta":{"title":"User prompt submitted hook","intro":"The onUserPromptSubmitted hook is called when a user submits a message. Use it to:","product":"GitHub Copilot","breadcrumbs":[{"href":"/en/copilot","title":"GitHub Copilot"},{"href":"/en/copilot/how-tos","title":"How-tos"},{"href":"/en/copilot/how-tos/copilot-sdk","title":"Copilot SDK"},{"href":"/en/copilot/how-tos/copilot-sdk/hooks","title":"Use hooks"},{"href":"/en/copilot/how-tos/copilot-sdk/hooks/user-prompt-submitted","title":"User Prompt Submitted"}],"documentType":"article"},"body":"# User prompt submitted hook\n\nThe onUserPromptSubmitted hook is called when a user submits a message. Use it to:\n\n\n\n\n\n* Modify or enhance user prompts\n* Add context before processing\n* Filter or validate user input\n* Implement prompt templates\n\n## Hook signature\n\n
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TypeScript
\n\n```typescript\ntype UserPromptSubmittedHandler = (\n input: UserPromptSubmittedHookInput,\n invocation: HookInvocation\n) => Promise;\n```\n\n
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Python
\n\n```python\nUserPromptSubmittedHandler = Callable[\n [UserPromptSubmittedHookInput, dict[str, str]],\n Awaitable[UserPromptSubmittedHookOutput | None]\n]\n```\n\n
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Go
\n\n```golang\ntype UserPromptSubmittedHandler func(\n input UserPromptSubmittedHookInput,\n invocation HookInvocation,\n) (*UserPromptSubmittedHookOutput, error)\n```\n\n
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.NET
\n\n```csharp\npublic delegate Task UserPromptSubmittedHandler(\n UserPromptSubmittedHookInput input,\n HookInvocation invocation);\n```\n\n
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Java
\n\n```java\n@FunctionalInterface\npublic interface UserPromptSubmittedHandler {\n CompletableFuture handle(\n UserPromptSubmittedHookInput input,\n HookInvocation invocation);\n}\n```\n\n
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\n\n## Input\n\n| Field | Type | Description |\n| ----------- | ------ | ------------------------------------------ |\n| `timestamp` | number | Unix timestamp when the hook was triggered |\n| `cwd` | string | Current working directory |\n| `prompt` | string | The user's submitted prompt |\n\n## Output\n\nReturn `null` or `undefined` to use the prompt unchanged. Otherwise, return an object with any of these fields:\n\n| Field | Type | Description |\n| ------------------- | ------- | ------------------------------------------------- |\n| `modifiedPrompt` | string | Modified prompt to use instead of original |\n| `additionalContext` | string | Extra context added to the conversation |\n| `suppressOutput` | boolean | If true, suppress the assistant's response output |\n\n## Examples\n\n### Log all user prompts\n\n
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TypeScript
\n\n```typescript\nconst session = await client.createSession({\n hooks: {\n onUserPromptSubmitted: async (input, invocation) => {\n console.log(`[${invocation.sessionId}] User: ${input.prompt}`);\n return null; // Pass through unchanged\n },\n },\n});\n```\n\n
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Python
\n\n```python\nfrom copilot.session import PermissionHandler\n\nasync def on_user_prompt_submitted(input_data, invocation):\n print(f\"[{invocation['session_id']}] User: {input_data['prompt']}\")\n return None\n\nsession = await client.create_session(on_permission_request=PermissionHandler.approve_all, hooks={\"on_user_prompt_submitted\": on_user_prompt_submitted})\n```\n\n
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Go
\n\n```golang\nsession, _ := client.CreateSession(context.Background(), &copilot.SessionConfig{\n Hooks: &copilot.SessionHooks{\n OnUserPromptSubmitted: func(input copilot.UserPromptSubmittedHookInput, inv copilot.HookInvocation) (*copilot.UserPromptSubmittedHookOutput, error) {\n fmt.Printf(\"[%s] User: %s\\n\", inv.SessionID, input.Prompt)\n return nil, nil\n },\n },\n})\n```\n\n
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.NET
\n\n```csharp\nvar session = await client.CreateSessionAsync(new SessionConfig\n{\n Hooks = new SessionHooks\n {\n OnUserPromptSubmitted = (input, invocation) =>\n {\n Console.WriteLine($\"[{invocation.SessionId}] User: {input.Prompt}\");\n return Task.FromResult(null);\n },\n },\n});\n```\n\n
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Java
\n\n\n\n```java\nimport com.github.copilot.*;\nimport com.github.copilot.rpc.*;\nimport java.util.concurrent.CompletableFuture;\n\nvar hooks = new SessionHooks()\n .setOnUserPromptSubmitted((input, invocation) -> {\n System.out.println(\"[\" + invocation.getSessionId() + \"] User: \" + input.prompt());\n return CompletableFuture.completedFuture(null);\n });\n\nvar session = client.createSession(\n new SessionConfig()\n .setOnPermissionRequest(PermissionHandler.APPROVE_ALL)\n .setHooks(hooks)\n).get();\n```\n\n
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\n\n### Add project context\n\n```typescript\nconst session = await client.createSession({\n hooks: {\n onUserPromptSubmitted: async (input) => {\n const projectInfo = await getProjectInfo();\n \n return {\n additionalContext: `\nProject: ${projectInfo.name}\nLanguage: ${projectInfo.language}\nFramework: ${projectInfo.framework}\n `.trim(),\n };\n },\n },\n});\n```\n\n### Expand shorthand commands\n\n```typescript\nconst SHORTCUTS: Record = {\n \"/fix\": \"Please fix the errors in the code\",\n \"/explain\": \"Please explain this code in detail\",\n \"/test\": \"Please write unit tests for this code\",\n \"/refactor\": \"Please refactor this code to improve readability and maintainability\",\n};\n\nconst session = await client.createSession({\n hooks: {\n onUserPromptSubmitted: async (input) => {\n for (const [shortcut, expansion] of Object.entries(SHORTCUTS)) {\n if (input.prompt.startsWith(shortcut)) {\n const rest = input.prompt.slice(shortcut.length).trim();\n return {\n modifiedPrompt: `${expansion}${rest ? `: ${rest}` : \"\"}`,\n };\n }\n }\n return null;\n },\n },\n});\n```\n\n### Content filtering\n\n```typescript\nconst BLOCKED_PATTERNS = [\n /password\\s*[:=]/i,\n /api[_-]?key\\s*[:=]/i,\n /secret\\s*[:=]/i,\n];\n\nconst session = await client.createSession({\n hooks: {\n onUserPromptSubmitted: async (input) => {\n for (const pattern of BLOCKED_PATTERNS) {\n if (pattern.test(input.prompt)) {\n // Replace the prompt with a warning message\n return {\n modifiedPrompt: \"[Content blocked: Please don't include sensitive credentials in your prompts. Use environment variables instead.]\",\n suppressOutput: true,\n };\n }\n }\n return null;\n },\n },\n});\n```\n\n### Enforce prompt length limits\n\n```typescript\nconst MAX_PROMPT_LENGTH = 10000;\n\nconst session = await client.createSession({\n hooks: {\n onUserPromptSubmitted: async (input) => {\n if (input.prompt.length > MAX_PROMPT_LENGTH) {\n // Truncate the prompt and add context\n return {\n modifiedPrompt: input.prompt.substring(0, MAX_PROMPT_LENGTH),\n additionalContext: `Note: The original prompt was ${input.prompt.length} characters and was truncated to ${MAX_PROMPT_LENGTH} characters.`,\n };\n }\n return null;\n },\n },\n});\n```\n\n### Add user preferences\n\n```typescript\ninterface UserPreferences {\n codeStyle: \"concise\" | \"verbose\";\n preferredLanguage: string;\n experienceLevel: \"beginner\" | \"intermediate\" | \"expert\";\n}\n\nconst session = await client.createSession({\n hooks: {\n onUserPromptSubmitted: async (input) => {\n const prefs: UserPreferences = await loadUserPreferences();\n \n const contextParts = [];\n \n if (prefs.codeStyle === \"concise\") {\n contextParts.push(\"User prefers concise code with minimal comments.\");\n } else {\n contextParts.push(\"User prefers verbose code with detailed comments.\");\n }\n \n if (prefs.experienceLevel === \"beginner\") {\n contextParts.push(\"Explain concepts in simple terms.\");\n }\n \n return {\n additionalContext: contextParts.join(\" \"),\n };\n },\n },\n});\n```\n\n### Usage threshold notices\n\n```typescript\nconst promptTimestamps: number[] = [];\nconst NOTICE_THRESHOLD = 10; // prompts\nconst RATE_WINDOW = 60000; // 1 minute\n\nconst session = await client.createSession({\n hooks: {\n onUserPromptSubmitted: async (input) => {\n const now = Date.now();\n \n // Remove timestamps outside the window\n while (promptTimestamps.length > 0 && promptTimestamps[0] < now - RATE_WINDOW) {\n promptTimestamps.shift();\n }\n\n promptTimestamps.push(now);\n if (promptTimestamps.length >= NOTICE_THRESHOLD) {\n // This is advisory context for the model, not an enforced rate limit.\n // Enforce hard limits before calling session.send().\n return {\n additionalContext: `The user has sent ${promptTimestamps.length} prompts in the last minute. Suggest waiting before sending more.`,\n };\n }\n\n return null;\n },\n },\n});\n```\n\n### Prompt templates\n\n```typescript\nconst TEMPLATES: Record string> = {\n \"bug:\": (desc) => `I found a bug: ${desc}\n\nPlease help me:\n1. Understand why this is happening\n2. Suggest a fix\n3. Explain how to prevent similar bugs`,\n\n \"feature:\": (desc) => `I want to implement this feature: ${desc}\n\nPlease:\n1. Outline the implementation approach\n2. Identify potential challenges\n3. Provide sample code`,\n};\n\nconst session = await client.createSession({\n hooks: {\n onUserPromptSubmitted: async (input) => {\n for (const [prefix, template] of Object.entries(TEMPLATES)) {\n if (input.prompt.toLowerCase().startsWith(prefix)) {\n const args = input.prompt.slice(prefix.length).trim();\n return {\n modifiedPrompt: template(args),\n };\n }\n }\n return null;\n },\n },\n});\n```\n\n## Best practices\n\n1. **Preserve user intent** - When modifying prompts, ensure the core intent remains clear.\n\n2. **Be transparent about modifications** - If you significantly change a prompt, consider logging or notifying the user.\n\n3. **Use `additionalContext` over `modifiedPrompt`** - Adding context is less intrusive than rewriting the prompt.\n\n4. **Use `additionalContext` for advisory guidance**: This hook cannot reject a prompt or enforce policy. Enforce hard limits before calling `session.send()`.\n\n5. **Keep processing fast** - This hook runs on every user message. Avoid slow operations.\n\n## See also\n\n* [Use hooks](/en/copilot/how-tos/copilot-sdk/hooks)\n* [Session lifecycle hooks](/en/copilot/how-tos/copilot-sdk/hooks/session-lifecycle)\n* [Pre-tool use hook](/en/copilot/how-tos/copilot-sdk/hooks/pre-tool-use)"}