From 392b039711c5c9af9afa5aa1c7aa5ec3b928c843 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sat, 11 Apr 2026 19:55:17 +0000
Subject: [PATCH 1/3] Initial plan


From 589ac38b055ac7af461921e643505b72946ade6a Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sat, 11 Apr 2026 20:24:20 +0000
Subject: [PATCH 2/3] fix: prevent ENOBUFS on large diffs in execGitSync by
 setting maxBuffer to 100MB

Set maxBuffer: 100 * 1024 * 1024 (100 MB) as the default in execGitSync's
spawnSync call, preventing ENOBUFS when git format-patch produces output
exceeding Node.js's default 1 MB buffer limit.

Also adds explicit ENOBUFS detection to surface an actionable error message
instead of the misleading "No changes to commit" fallback.

Closes #1612

Agent-Logs-Url: https://github.com/github/gh-aw/sessions/38d92d89-2d17-4599-b7fe-7b38765cfc33

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>
---
 .changeset/patch-fix-create-pr-enobufs.md | 12 ++++++++++++
 actions/setup/js/git_helpers.cjs          | 10 ++++++++++
 actions/setup/js/git_helpers.test.cjs     |  9 +++++++++
 3 files changed, 31 insertions(+)
 create mode 100644 .changeset/patch-fix-create-pr-enobufs.md

diff --git a/.changeset/patch-fix-create-pr-enobufs.md b/.changeset/patch-fix-create-pr-enobufs.md
new file mode 100644
index 00000000000..e3e006f3c17
--- /dev/null
+++ b/.changeset/patch-fix-create-pr-enobufs.md
@@ -0,0 +1,12 @@
+---
+"gh-aw": patch
+---
+
+Fixed `create_pull_request` failing with `spawnSync git ENOBUFS` on large diffs (e.g. 47+ changed files).
+
+The `execGitSync` helper in `git_helpers.cjs` used Node.js `spawnSync` without an explicit `maxBuffer`, defaulting to ~1 MB. When `git format-patch --stdout` produced output exceeding that limit, all patch generation strategies silently failed with a misleading "No changes to commit" error.
+
+The fix:
+- Set `maxBuffer: 100 * 1024 * 1024` (100 MB) as the default in `execGitSync`, matching the `max_patch_size` headroom and consistent with other handlers in the codebase (e.g. MCP handlers use 10 MB).
+- Detect `ENOBUFS` errors and throw an actionable error message that surfaces the real cause instead of the generic "no commits found" fallback.
+- Callers can still override `maxBuffer` via the options spread.
diff --git a/actions/setup/js/git_helpers.cjs b/actions/setup/js/git_helpers.cjs
index 84bf2b65630..3ae9dcc8330 100644
--- a/actions/setup/js/git_helpers.cjs
+++ b/actions/setup/js/git_helpers.cjs
@@ -66,10 +66,20 @@ function execGitSync(args, options = {}) {
 
   const result = spawnSync("git", args, {
     encoding: "utf8",
+    maxBuffer: 100 * 1024 * 1024, // 100 MB — prevents ENOBUFS on large diffs (e.g. git format-patch)
     ...spawnOptions,
   });
 
   if (result.error) {
+    // Detect ENOBUFS (buffer overflow) and provide a more actionable message
+    if (result.error.code === "ENOBUFS") {
+      const bufferError = new Error(
+        `${ERR_SYSTEM}: Git command output exceeded buffer limit (ENOBUFS). ` + `The output from '${args[0]}' is too large for the configured maxBuffer. ` + `Consider reducing the diff size or increasing maxBuffer.`
+      );
+      bufferError.code = "ENOBUFS";
+      core.error(`Git command buffer overflow: ${gitCommand}`);
+      throw bufferError;
+    }
     // Spawn-level errors (e.g. ENOENT, EACCES) are always unexpected — log
     // via core.error regardless of suppressLogs.
     core.error(`Git command failed with error: ${result.error.message}`);
diff --git a/actions/setup/js/git_helpers.test.cjs b/actions/setup/js/git_helpers.test.cjs
index 04d35c76e20..63f5d886a06 100644
--- a/actions/setup/js/git_helpers.test.cjs
+++ b/actions/setup/js/git_helpers.test.cjs
@@ -80,6 +80,15 @@ describe("git_helpers.cjs", () => {
       expect(result).toContain("git version");
     });
 
+    it("should throw actionable ENOBUFS error when maxBuffer is exceeded", async () => {
+      const { execGitSync } = await import("./git_helpers.cjs");
+
+      // Use a tiny maxBuffer to trigger ENOBUFS on any git output
+      expect(() => {
+        execGitSync(["--version"], { maxBuffer: 1 });
+      }).toThrow(/ENOBUFS|buffer limit/i);
+    });
+
     it("should return stdout from successful commands", async () => {
       const { execGitSync } = await import("./git_helpers.cjs");
 

From fdc7edd295d888c6dc4464e986ce927dfc65554a Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sat, 11 Apr 2026 20:25:21 +0000
Subject: [PATCH 3/3] style: use single template literal for ENOBUFS error
 message

Agent-Logs-Url: https://github.com/github/gh-aw/sessions/38d92d89-2d17-4599-b7fe-7b38765cfc33

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>
---
 actions/setup/js/git_helpers.cjs | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/actions/setup/js/git_helpers.cjs b/actions/setup/js/git_helpers.cjs
index 3ae9dcc8330..c7013a7bcb5 100644
--- a/actions/setup/js/git_helpers.cjs
+++ b/actions/setup/js/git_helpers.cjs
@@ -73,9 +73,7 @@ function execGitSync(args, options = {}) {
   if (result.error) {
     // Detect ENOBUFS (buffer overflow) and provide a more actionable message
     if (result.error.code === "ENOBUFS") {
-      const bufferError = new Error(
-        `${ERR_SYSTEM}: Git command output exceeded buffer limit (ENOBUFS). ` + `The output from '${args[0]}' is too large for the configured maxBuffer. ` + `Consider reducing the diff size or increasing maxBuffer.`
-      );
+      const bufferError = new Error(`${ERR_SYSTEM}: Git command output exceeded buffer limit (ENOBUFS). The output from '${args[0]}' is too large for the configured maxBuffer. Consider reducing the diff size or increasing maxBuffer.`);
       bufferError.code = "ENOBUFS";
       core.error(`Git command buffer overflow: ${gitCommand}`);
       throw bufferError;