fix: prepare commit message hook no longer fires on merge/squash/etc

dot_config/git/template/hooks/executable_prepare-commit-msg.tmpl

@@ -4,52 +4,38 @@
 /*{{ if lookPath "node" -}}*/
 #!/usr/bin/env node
 
-const fs = require("fs");
-const childProcess = require("child_process");
-const { promisify } = require("util");
+// Add a "# [TICKET-ID]" comment hint to the editor when running a plain
+// `git commit` on a branch containing a ticket ID (e.g. buddy/BE-1234/foo,
+// fix/BE-1234/bar). The hint is a comment, so git strips it unless you
+// uncomment or retype it.
+//
+// Every other way a commit message gets made is left alone: -m/-F
+// ("message"), merge, squash, amend/-c ("commit"), and commit templates
+// ("template") all arrive with a mode argument, and we exit immediately.
 
-const exec = promisify(childProcess.exec);
-const readFile = promisify(fs.readFile);
-const writeFile = promisify(fs.writeFile);
+import * as fs from "node:fs";
+import { execSync } from "node:child_process";
 
-const [, , message, mode] = process.argv;
+const [, , messagePath, mode] = process.argv;
 
-async function main() {
-  const file = await readFile(message, { encoding: "utf8" });
-  let result;
-  try {
-    result = await exec("git rev-parse --abbrev-ref HEAD");
-  } catch (err) {
-    return
-  }
+if (mode !== undefined) process.exit(0);
 
-  if (message.match(/^#/)) {
-    return
-  }
-
-  const tags = result.stdout
-    .split("\n")
-    .map(branch => branch.match(/[A-Z]+-\d+/g))
-    .filter(x => !!x)
-    .reduce((allIDs, matchedIDs) => [...allIDs, ...matchedIDs], [])
-    .map(id => `[${id}]`);
-
-  if (tags.length === 0) {
-    return;
-  }
-  if (tags.find(tag => file.includes(tag))) {
-    return;
-  }
-
-  const newFile = mode === 'message'
-    ? file + '\n\n'  + tags.join(" ")
-    : `\n\n# ` + tags.join(" ") + "\n" + file;
-
-  await writeFile(message, newFile);
+let branch;
+try {
+  branch = execSync("git rev-parse --abbrev-ref HEAD", {
+    encoding: "utf8",
+    stdio: ["ignore", "pipe", "ignore"],
+  }).trim();
+} catch {
+  process.exit(0); // detached HEAD, rebase, etc.
 }
 
-main().catch(err => {
-  console.error(err);
-  process.exit(1);
-});
+const ids = branch.match(/[A-Z]+-\d+/g);
+if (!ids) process.exit(0);
+
+const tags = [...new Set(ids)].map(id => `[${id}]`);
+const file = fs.readFileSync(messagePath, "utf8");
+if (tags.some(tag => file.includes(tag))) process.exit(0);
+
+fs.writeFileSync(messagePath, `\n\n# ${tags.join(" ")}\n${file}`);
 /*{{- end }}*/