Determinstically set up PR branch

mcp/prInfo.ts

@@ -1,6 +1,4 @@
 import { type } from "arktype";
-import { log } from "../utils/cli.ts";
-import { $ } from "../utils/shell.ts";
 import { contextualize, tool } from "./shared.ts";
 
 export const PullRequestInfo = type({
@@ -9,7 +7,8 @@ export const PullRequestInfo = type({
 
 export const PullRequestInfoTool = tool({
   name: "get_pull_request",
-  description: "Retrieve PR information. Automatically fetches and checks out the PR branch.",
+  description:
+    "Retrieve PR information (metadata only). PR branch is already checked out during setup.",
   parameters: PullRequestInfo,
   execute: contextualize(async ({ pull_number }, ctx) => {
     const pr = await ctx.octokit.rest.pulls.get({
@@ -20,38 +19,8 @@ export const PullRequestInfoTool = tool({
 
     const data = pr.data;
 
-    const baseBranch = data.base.ref;
-    const headBranch = data.head.ref;
-
-    if (!baseBranch) {
-      throw new Error(`Base branch not found for PR #${pull_number}`);
-    }
-
     // detect fork PRs - head repo differs from base repo
-    const baseRepo = data.base.repo.full_name;
-    const headRepo = data.head.repo.full_name;
-    const isFork = headRepo !== baseRepo;
-
-    // use gh pr checkout which handles fork PRs automatically
-    // it adds the fork as a remote if needed and checks out the PR branch
-    log.info(`Checking out PR #${pull_number} using gh pr checkout`);
-    $("gh", ["pr", "checkout", pull_number.toString()]);
-
-    // fetch base branch for diff comparison
-    log.info(`Fetching base branch: origin/${baseBranch}`);
-    $("git", ["fetch", "origin", baseBranch, "--depth=20"]);
-
-    // get current git status for summary
-    const currentBranch = $("git", ["rev-parse", "--abbrev-ref", "HEAD"], { log: false }).trim();
-    const currentSha = $("git", ["rev-parse", "HEAD"], { log: false }).trim();
-    const baseSha = $("git", ["rev-parse", `origin/${baseBranch}`], { log: false }).trim();
-
-    // build summary
-    const summary = `PR branch has been fetched and checked out:
-- Base branch: \`origin/${baseBranch}\` (${baseSha.substring(0, 7)})
-- PR branch: \`${headBranch}\` (checked out locally, ${currentSha.substring(0, 7)})
-- Current branch: \`${currentBranch}\`
-- View diff: \`git diff origin/${baseBranch}...HEAD\``;
+    const isFork = data.head.repo.full_name !== data.base.repo.full_name;
 
     return {
       number: data.number,
@@ -60,10 +29,9 @@ export const PullRequestInfoTool = tool({
       state: data.state,
       draft: data.draft,
       merged: data.merged,
-      base: baseBranch,
-      head: headBranch,
+      base: data.base.ref,
+      head: data.head.ref,
       isFork,
-      summary,
     };
   }),
 });