Minify JS bundle on release branches

.github/update-release-branch.py

@@ -56,9 +56,8 @@ def run_command(*args):
 
 # Rebuilds the action and commits any changes.
 def rebuild_action():
-  # For backports, the only source-level change vs the source branch is the new version number,
-  # so we just need to refresh the version embedded in `lib/`.
   run_command('npm', 'ci')
+  # We only expect changes to the JavaScript output, rebuilding e.g. the PR checks is unnecessary.
   run_command('npm', 'run', 'build')
 
   run_git('add', '--all')
@@ -450,12 +449,11 @@ def main():
     run_git('add', 'CHANGELOG.md')
     run_git('commit', '-m', f'Update changelog for v{version}')
 
-  if not is_primary_release:
-    if len(conflicted_files) == 0:
-      print('Rebuilding the Action.')
-      rebuild_action()
-    else:
-      print(f'Skipping automatic rebuild because the merge produced conflicts in {conflicted_files}.')
+  if len(conflicted_files) > 0:
+    print(f'Skipping automatic rebuild because the merge produced conflicts in {conflicted_files}.')
+  else:
+    print('Rebuilding the Action.')
+    rebuild_action()
 
   run_git('push', ORIGIN, new_branch_name)
 

CHANGELOG.md

@@ -6,6 +6,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 
 - _Breaking change_: Bump the minimum required CodeQL bundle version to 2.19.4. [#3894](https://github.com/github/codeql-action/pull/3894)
 - Add support for SHA-256 Git object IDs. [#3893](https://github.com/github/codeql-action/pull/3893)
+- The JavaScript bundle shipped on release branches is now minified, reducing the size of the repository by around 20%. Bundles on `main` remain unminified to avoid merge conflicts between PRs. [#3920](https://github.com/github/codeql-action/pull/3920)
 
 ## 4.35.5 - 15 May 2026
 

build.mjs

@@ -1,3 +1,4 @@
+import { execFileSync } from "node:child_process";
 import { copyFile, readFile, rm, writeFile } from "node:fs/promises";
 import { basename, dirname, join } from "node:path";
 import { fileURLToPath } from "node:url";
@@ -13,6 +14,51 @@ const __dirname = dirname(__filename);
 const SRC_DIR = join(__dirname, "src");
 const OUT_DIR = join(__dirname, "lib");
 
+/**
+ * Decide whether to minify the bundle.
+ *
+ * We deliberately do not minify by default to avoid making every PR's regenerated bundle conflict
+ * with every other PR. Instead, we minify only when building for a release branch so consumers of
+ * `github/codeql-action/<action>@vN` get the smaller bundle while day-to-day development on `main`
+ * stays low-churn.
+ *
+ * @returns {boolean}
+ */
+function shouldMinify() {
+  const override = process.env.CODEQL_ACTION_MINIFY;
+  if (override === "true") return true;
+  if (override === "false") return false;
+
+  // In `pull_request` and `merge_group` contexts, we can just look at the base ref.
+  if (process.env.GITHUB_BASE_REF) {
+    return process.env.GITHUB_BASE_REF.startsWith("releases/v");
+  }
+
+  // When running locally or in contexts without a base ref (e.g. `push`, `workflow_dispatch`),
+  // check whether we're running as part of the release automation by looking at the local branch
+  // name. Mergebacks target `main` and should not be minified, while update and backport branches
+  // target release branches and should be minified.
+  const localBranch = getLocalBranchName();
+  if (localBranch?.startsWith("mergeback/")) return false;
+  if (localBranch && /^(update|backport)-v\d/.test(localBranch)) return true;
+
+  // If we don't seem to be running as part of the release automation, then only minify if we're on
+  // a release branch.
+  const refName = process.env.GITHUB_REF_NAME || localBranch;
+  return !!refName && refName.startsWith("releases/v");
+}
+
+function getLocalBranchName() {
+  try {
+    return execFileSync("git", ["rev-parse", "--abbrev-ref", "HEAD"], {
+      encoding: "utf-8",
+      stdio: ["pipe", "pipe", "ignore"],
+    }).trim();
+  } catch {
+    return undefined;
+  }
+}
+
 /**
  * Clean the output directory before building.
  *
@@ -201,10 +247,17 @@ const entryPointsPlugin = {
   },
 };
 
+const minify = shouldMinify();
+if (minify) {
+  // eslint-disable-next-line no-console
+  console.log("Minification enabled for this build.");
+}
+
 const context = await esbuild.context({
   entryPoints: [{ in: SHARED_ENTRYPOINT, out: SHARED_ENTRYPOINT }],
   bundle: true,
   format: "cjs",
+  minify,
   outdir: OUT_DIR,
   platform: "node",
   external: ["./entry-points"],