feat: Lifecycle hooks (#219)

* flatten lifecycle hooks into RepoSettings string fields

replace the separate LifecycleHook model with setupScript and
postCheckoutScript string fields directly on RepoSettings. move the UI
into the Agent settings section alongside environment variables and
custom instructions. delete the standalone lifecycle-hooks API route,
component, and schema since the existing settings PATCH endpoint
handles the new fields automatically.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix: pass env to lifecycle hook spawn so scripts can use package managers

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Colin McDonnell <colinmcd94@gmail.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

mcp/checkout.ts

@@ -4,8 +4,9 @@ import type { Octokit, RestEndpointMethodTypes } from "@octokit/rest";
 import { type } from "arktype";
 import { log } from "../utils/cli.ts";
 import { $git } from "../utils/gitAuth.ts";
+import { executeLifecycleHook } from "../utils/lifecycle.ts";
 import { $ } from "../utils/shell.ts";
-import type { ToolContext, ToolState } from "./server.ts";
+import type { ToolContext } from "./server.ts";
 import { execute, tool } from "./shared.ts";
 
 type PullFile = RestEndpointMethodTypes["pulls"]["listFiles"]["response"]["data"][number];
@@ -162,16 +163,9 @@ export async function fetchAndFormatPrDiff(params: FetchPrDiffParams): Promise<F
   return formatFilesWithLineNumbers(filesResponse.data);
 }
 
-interface CheckoutPrBranchParams {
-  octokit: Octokit;
-  owner: string;
-  name: string;
-  gitToken: string;
-  pullNumber: number;
-  toolState: ToolState;
-  // restricted bash mode: disables git hooks to prevent token exfiltration
-  restricted: boolean;
-}
+import type { GitContext } from "../utils/setup.ts";
+
+type CheckoutPrBranchParams = GitContext;
 
 interface CheckoutPrBranchResult {
   prNumber: number;
@@ -185,9 +179,10 @@ interface CheckoutPrBranchResult {
  * Updates toolState.issueNumber and toolState.pushUrl (for fork PRs).
  */
 export async function checkoutPrBranch(
+  pullNumber: number,
   params: CheckoutPrBranchParams
 ): Promise<CheckoutPrBranchResult> {
-  const { octokit, owner, name, gitToken, pullNumber, toolState, restricted } = params;
+  const { octokit, owner, name, gitToken, toolState, restricted } = params;
   log.info(`» checking out PR #${pullNumber}...`);
 
   // fetch PR metadata
@@ -288,6 +283,12 @@ export async function checkoutPrBranch(
     toolState.pushUrl = `https://github.com/${headRepo.full_name}.git`;
   }
 
+  // execute post-checkout lifecycle hook
+  await executeLifecycleHook({
+    event: "post-checkout",
+    script: params.postCheckoutScript,
+  });
+
   return {
     prNumber: pullNumber,
     isFork,
@@ -303,14 +304,14 @@ export function CheckoutPrTool(ctx: ToolContext) {
       "Returns diffPath pointing to the formatted diff file.",
     parameters: CheckoutPr,
     execute: execute(async ({ pull_number }) => {
-      const result = await checkoutPrBranch({
+      await checkoutPrBranch(pull_number, {
         octokit: ctx.octokit,
         owner: ctx.repo.owner,
         name: ctx.repo.name,
         gitToken: ctx.gitToken,
-        pullNumber: pull_number,
         toolState: ctx.toolState,
         restricted: ctx.payload.bash === "restricted",
+        postCheckoutScript: ctx.postCheckoutScript,
       });
 
       // fetch PR metadata to return result

mcp/server.ts

@@ -67,6 +67,7 @@ export interface ToolContext {
   apiToken: string;
   agent: Agent;
   modes: Mode[];
+  postCheckoutScript: string | null;
   toolState: ToolState;
   runId: string;
   jobId: string | undefined;