fix: regenerate PR title and body when updating existing pull request

apps/server/src/git/Layers/GitHubCli.ts

@@ -272,6 +272,17 @@ const makeGitHubCli = Effect.sync(() => {
         cwd: input.cwd,
         args: ["pr", "checkout", input.reference, ...(input.force ? ["--force"] : [])],
       }).pipe(Effect.asVoid),
+    editPullRequest: (input) =>
+      execute({
+        cwd: input.cwd,
+        args: [
+          "pr",
+          "edit",
+          String(input.number),
+          ...(input.title ? ["--title", input.title] : []),
+          ...(input.bodyFile ? ["--body-file", input.bodyFile] : []),
+        ],
+      }).pipe(Effect.asVoid),
   } satisfies GitHubCliShape;
 
   return service;

apps/server/src/git/Layers/GitManager.ts

@@ -889,19 +889,9 @@ export const makeGitManager = Effect.fn("makeGitManager")(function* () {
       upstreamRef: details.upstreamRef,
     });
 
+    const baseBranch = yield* resolveBaseBranch(cwd, branch, details.upstreamRef, headContext);
     const existing = yield* findOpenPr(cwd, headContext.headSelectors);
-    if (existing) {
-      return {
-        status: "opened_existing" as const,
-        url: existing.url,
-        number: existing.number,
-        baseBranch: existing.baseRefName,
-        headBranch: existing.headRefName,
-        title: existing.title,
-      };
-    }
 
-    const baseBranch = yield* resolveBaseBranch(cwd, branch, details.upstreamRef, headContext);
     const rangeContext = yield* gitCore.readRangeContext(cwd, baseBranch);
 
     const generated = yield* textGeneration.generatePrContent({
@@ -922,6 +912,27 @@ export const makeGitManager = Effect.fn("makeGitManager")(function* () {
           gitManagerError("runPrStep", "Failed to write pull request body temp file.", cause),
         ),
       );
+
+    if (existing) {
+      yield* gitHubCli
+        .editPullRequest({
+          cwd,
+          number: existing.number,
+          title: generated.title,
+          bodyFile,
+        })
+        .pipe(Effect.ensuring(fileSystem.remove(bodyFile).pipe(Effect.catch(() => Effect.void))));
+
+      return {
+        status: "opened_existing" as const,
+        url: existing.url,
+        number: existing.number,
+        baseBranch: existing.baseRefName,
+        headBranch: existing.headRefName,
+        title: generated.title,
+      };
+    }
+
     yield* gitHubCli
       .createPullRequest({
         cwd,

apps/server/src/git/Services/GitHubCli.ts

@@ -93,6 +93,16 @@ export interface GitHubCliShape {
     readonly reference: string;
     readonly force?: boolean;
   }) => Effect.Effect<void, GitHubCliError>;
+
+  /**
+   * Edit an existing pull request's title and/or body.
+   */
+  readonly editPullRequest: (input: {
+    readonly cwd: string;
+    readonly number: number;
+    readonly title?: string;
+    readonly bodyFile?: string;
+  }) => Effect.Effect<void, GitHubCliError>;
 }
 
 /**