{"meta":{"title":"Session hooks","intro":"Hooks allow you to intercept and customize the behavior of Copilot sessions at key points in the conversation lifecycle. Use hooks to:","product":"GitHub Copilot","breadcrumbs":[{"href":"/en/enterprise-cloud@latest/copilot","title":"GitHub Copilot"},{"href":"/en/enterprise-cloud@latest/copilot/how-tos","title":"How-tos"},{"href":"/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk","title":"Copilot SDK"},{"href":"/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks","title":"Use hooks"},{"href":"/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/hooks-overview","title":"Hooks Overview"}],"documentType":"article"},"body":"# Session hooks\n\nHooks allow you to intercept and customize the behavior of Copilot sessions at key points in the conversation lifecycle. Use hooks to:\n\n\n\n\n\n* **Control tool execution** - approve, deny, or modify tool calls\n* **Transform results** - modify tool outputs before they're processed\n* **Add context** - inject additional information at session start\n* **Handle errors** - implement custom error handling\n* **Audit and log** - track all interactions for compliance\n\n## Available hooks\n\n| Hook | Trigger | Use Case |\n| ------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------- | ------------------------------------------- |\n| [Pre-tool use hook](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/pre-tool-use) | Before a tool executes | Permission control, argument validation |\n| [Post-tool use hook](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/post-tool-use) | After a tool executes (success only) | Result transformation, logging |\n| [Post-tool use hook](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/post-tool-use#failure-variant) | After a tool execution whose result was a failure | Inject retry guidance, log failures |\n| [User prompt submitted hook](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/user-prompt-submitted) | When user sends a message | Prompt modification, filtering |\n| [User prompt transformed hook](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/user-prompt-transformed) | After runtime prompt transformation | Inspect or replace model-facing content |\n| [Session lifecycle hooks](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/session-lifecycle#session-start) | Session begins | Add context, configure session |\n| [Session lifecycle hooks](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/session-lifecycle#session-end) | Session ends | Cleanup, analytics |\n| [Error handling hook](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/error-handling) | Error happens | Custom error handling |\n| [Session lifecycle hooks](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/session-lifecycle#agent-stop) | Top-level agent naturally stops | Validate completion or request another turn |\n\n## Quick start\n\n
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TypeScript
\n\n```typescript\nimport { CopilotClient } from \"@github/copilot-sdk\";\n\nconst client = new CopilotClient();\n\nconst session = await client.createSession({\n hooks: {\n onPreToolUse: async (input) => {\n console.log(`Tool called: ${input.toolName}`);\n // Allow all tools\n return { permissionDecision: \"allow\" };\n },\n onPostToolUse: async (input) => {\n console.log(`Tool result: ${JSON.stringify(input.toolResult)}`);\n return null; // No modifications\n },\n onSessionStart: async (input) => {\n return { additionalContext: \"User prefers concise answers.\" };\n },\n },\n});\n```\n\n
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Python
\n\n```python\nfrom copilot import CopilotClient\nfrom copilot.session import PermissionHandler\n\nasync def main():\n client = CopilotClient()\n await client.start()\n\n async def on_pre_tool_use(input_data, invocation):\n print(f\"Tool called: {input_data['toolName']}\")\n return {\"permissionDecision\": \"allow\"}\n\n async def on_post_tool_use(input_data, invocation):\n print(f\"Tool result: {input_data['toolResult']}\")\n return None\n\n async def on_session_start(input_data, invocation):\n return {\"additionalContext\": \"User prefers concise answers.\"}\n\n session = await client.create_session(on_permission_request=PermissionHandler.approve_all, hooks={\n \"on_pre_tool_use\": on_pre_tool_use,\n \"on_post_tool_use\": on_post_tool_use,\n \"on_session_start\": on_session_start,\n })\n```\n\n
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Go
\n\n```golang\npackage main\n\nimport (\n \"context\"\n \"fmt\"\n copilot \"github.com/github/copilot-sdk/go\"\n)\n\nfunc main() {\n client := copilot.NewClient(nil)\n\n session, _ := client.CreateSession(context.Background(), &copilot.SessionConfig{\n Hooks: &copilot.SessionHooks{\n OnPreToolUse: func(input copilot.PreToolUseHookInput, inv copilot.HookInvocation) (*copilot.PreToolUseHookOutput, error) {\n fmt.Printf(\"Tool called: %s\\n\", input.ToolName)\n return &copilot.PreToolUseHookOutput{\n PermissionDecision: \"allow\",\n }, nil\n },\n OnPostToolUse: func(input copilot.PostToolUseHookInput, inv copilot.HookInvocation) (*copilot.PostToolUseHookOutput, error) {\n fmt.Printf(\"Tool result: %v\\n\", input.ToolResult)\n return nil, nil\n },\n OnSessionStart: func(input copilot.SessionStartHookInput, inv copilot.HookInvocation) (*copilot.SessionStartHookOutput, error) {\n return &copilot.SessionStartHookOutput{\n AdditionalContext: \"User prefers concise answers.\",\n }, nil\n },\n },\n })\n _ = session\n}\n```\n\n
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.NET
\n\n```csharp\nusing GitHub.Copilot;\n\nvar client = new CopilotClient();\n\nvar session = await client.CreateSessionAsync(new SessionConfig\n{\n Hooks = new SessionHooks\n {\n OnPreToolUse = (input, invocation) =>\n {\n Console.WriteLine($\"Tool called: {input.ToolName}\");\n return Task.FromResult(\n new PreToolUseHookOutput { PermissionDecision = \"allow\" }\n );\n },\n OnPostToolUse = (input, invocation) =>\n {\n Console.WriteLine($\"Tool result: {input.ToolResult}\");\n return Task.FromResult(null);\n },\n OnSessionStart = (input, invocation) =>\n {\n return Task.FromResult(\n new SessionStartHookOutput { AdditionalContext = \"User prefers concise answers.\" }\n );\n },\n },\n});\n```\n\n
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Java
\n\n```java\nimport com.github.copilot.*;\nimport com.github.copilot.rpc.*;\nimport java.util.concurrent.CompletableFuture;\n\ntry (var client = new CopilotClient()) {\n client.start().get();\n\n var hooks = new SessionHooks()\n .setOnPreToolUse((input, invocation) -> {\n System.out.println(\"Tool called: \" + input.getToolName());\n return CompletableFuture.completedFuture(PreToolUseHookOutput.allow());\n })\n .setOnPostToolUse((input, invocation) -> {\n System.out.println(\"Tool result: \" + input.getToolResult());\n return CompletableFuture.completedFuture(null);\n })\n .setOnSessionStart((input, invocation) -> {\n return CompletableFuture.completedFuture(\n new SessionStartHookOutput(\"User prefers concise answers.\", null)\n );\n });\n\n var session = client.createSession(\n new SessionConfig()\n .setHooks(hooks)\n .setOnPermissionRequest(PermissionHandler.APPROVE_ALL)\n ).get();\n}\n```\n\n
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\n\n## Hook invocation context\n\nEvery hook receives an `invocation` parameter with context about the current session:\n\n| Field | Type | Description |\n| ----------- | ------ | ----------------------------- |\n| `sessionId` | string | The ID of the current session |\n\nThis allows hooks to maintain state or perform session-specific logic.\n\n## Common patterns\n\n### Logging all tool calls\n\n```typescript\nconst session = await client.createSession({\n hooks: {\n onPreToolUse: async (input) => {\n console.log(`[${new Date().toISOString()}] Tool: ${input.toolName}, Args: ${JSON.stringify(input.toolArgs)}`);\n return { permissionDecision: \"allow\" };\n },\n onPostToolUse: async (input) => {\n console.log(`[${new Date().toISOString()}] Result: ${JSON.stringify(input.toolResult)}`);\n return null;\n },\n },\n});\n```\n\n### Blocking dangerous tools\n\n```typescript\nconst BLOCKED_TOOLS = [\"shell\", \"bash\", \"exec\"];\n\nconst session = await client.createSession({\n hooks: {\n onPreToolUse: async (input) => {\n if (BLOCKED_TOOLS.includes(input.toolName)) {\n return {\n permissionDecision: \"deny\",\n permissionDecisionReason: \"Shell access is not permitted\",\n };\n }\n return { permissionDecision: \"allow\" };\n },\n },\n});\n```\n\n### Adding user context\n\n```typescript\nconst session = await client.createSession({\n hooks: {\n onSessionStart: async () => {\n const userPrefs = await loadUserPreferences();\n return {\n additionalContext: `User preferences: ${JSON.stringify(userPrefs)}`,\n };\n },\n },\n});\n```\n\n## Hook guides\n\n* **[Pre-tool use hook](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/pre-tool-use)** - Control tool execution permissions\n* **[Post-tool use hook](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/post-tool-use)** - Transform tool results\n* **[User prompt submitted hook](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/user-prompt-submitted)** - Modify user prompts\n* **[User prompt transformed hook](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/user-prompt-transformed)** - Replace model-facing prompts\n* **[Session lifecycle hooks](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/session-lifecycle)** - Session start and end\n* **[Session lifecycle hooks](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/session-lifecycle#agent-stop)** - Validate completion before the agent stops\n* **[Error handling hook](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/error-handling)** - Custom error handling\n\n## See also\n\n* [Build your first Copilot-powered app](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/getting-started)\n* [Build your first Copilot-powered app](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/getting-started#step-4-add-a-custom-tool)\n* [Debugging guide](/en/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/troubleshooting/debugging)"}