diff --git a/scripts/merge-pr.test.ts b/scripts/merge-pr.test.ts
new file mode 100644
index 000000000..ae35dec08
--- /dev/null
+++ b/scripts/merge-pr.test.ts
@@ -0,0 +1,28 @@
+import { describe, expect, test } from "bun:test";
+import { isCompliantSubject } from "./merge-pr";
+
+describe("isCompliantSubject", () => {
+	test("accepts conventional subjects, including scope and bang", () => {
+		expect(isCompliantSubject("fix: added thing")).toBe(true);
+		expect(isCompliantSubject("feat(catalog): added native meta provider")).toBe(true);
+		expect(isCompliantSubject("refactor(tui)!: dropped legacy renderer")).toBe(true);
+	});
+
+	test("rejects prefix-only false positives", () => {
+		expect(isCompliantSubject("fix: Add Thing.")).toBe(false); // uppercase + period
+		expect(isCompliantSubject("fix: Added thing")).toBe(false); // uppercase description
+		expect(isCompliantSubject("fix: added thing.")).toBe(false); // trailing period
+		expect(isCompliantSubject(`fix: ${"a".repeat(70)}`)).toBe(false); // >72 chars total
+	});
+
+	test("rejects subjects without a conventional prefix", () => {
+		expect(isCompliantSubject("added thing")).toBe(false);
+		expect(isCompliantSubject("Fix: added thing")).toBe(false);
+		expect(isCompliantSubject("fix:")).toBe(false);
+	});
+
+	test("selection skips earlier noncompliant commits", () => {
+		const subjects = ["fix: Add Thing.", "WIP", "fix: added thing", "feat: also fine"];
+		expect(subjects.find(isCompliantSubject)).toBe("fix: added thing");
+	});
+});
diff --git a/scripts/merge-pr.ts b/scripts/merge-pr.ts
new file mode 100755
index 000000000..535266e33
--- /dev/null
+++ b/scripts/merge-pr.ts
@@ -0,0 +1,139 @@
+#!/usr/bin/env bun
+/**
+ * Merge a local PR branch with the repo's merge-commit schema:
+ *
+ *   Merge PR #<number>: <conventional PR subject> (@<author>)
+ *
+ * PR number and author are resolved via `gh`. The subject is taken from the
+ * first (oldest) conventional-compliant commit in `HEAD..<branch>`; if none
+ * exists the command fails rather than emit a noncompliant message.
+ *
+ * Usage:
+ *   bun scripts/merge-pr.ts <branch>              # resolve PR from branch head
+ *   bun scripts/merge-pr.ts <branch> --pr 6386    # explicit PR number
+ *   bun scripts/merge-pr.ts <branch> --dry-run    # print message, don't merge
+ *
+ * Handy alias:
+ *   git config alias.mpr '!bun scripts/merge-pr.ts'
+ *   git mpr feature-branch
+ */
+import { $ } from "bun";
+
+interface PrMeta {
+	number: number;
+	title: string;
+	author: { login: string };
+}
+
+function fail(msg: string): never {
+	console.error(`error: ${msg}`);
+	process.exit(1);
+}
+
+function parseArgs(argv: string[]) {
+	let branch: string | undefined;
+	let pr: number | undefined;
+	let dryRun = false;
+	for (let i = 0; i < argv.length; i++) {
+		const arg = argv[i];
+		if (arg === "--dry-run" || arg === "-n") dryRun = true;
+		else if (arg === "--pr") {
+			const val = argv[++i];
+			if (!val || !/^\d+$/.test(val)) fail("--pr requires a numeric PR number");
+			pr = Number(val);
+		} else if (arg === "--help" || arg === "-h") {
+			console.log("usage: merge-pr.ts <branch> [--pr <number>] [--dry-run]");
+			process.exit(0);
+		} else if (arg.startsWith("-")) fail(`unknown flag: ${arg}`);
+		else if (branch) fail(`unexpected argument: ${arg}`);
+		else branch = arg;
+	}
+	if (!branch) fail("usage: merge-pr.ts <branch> [--pr <number>] [--dry-run]");
+	return { branch, pr, dryRun };
+}
+
+/** Pull a PR number out of branch names like `pr/6386`, `pr-6386`, `6386-fix-foo`. */
+function prNumberFromBranchName(branch: string): number | undefined {
+	const m = branch.match(/(?:^|[/_-])pr[/_-]?(\d+)(?:$|[/_-])/i) ?? branch.match(/^(\d+)[/_-]/);
+	return m ? Number(m[1]) : undefined;
+}
+
+async function ghPrView(selector: string): Promise<PrMeta | undefined> {
+	const res = await $`gh pr view ${selector} --json number,title,author`.quiet().nothrow();
+	if (res.exitCode !== 0) return undefined;
+	try {
+		return res.json() as PrMeta;
+	} catch {
+		return undefined;
+	}
+}
+
+async function resolvePr(branch: string, explicit: number | undefined): Promise<PrMeta> {
+	if (explicit !== undefined) {
+		const meta = await ghPrView(String(explicit));
+		if (!meta) fail(`gh could not find PR #${explicit}`);
+		return meta;
+	}
+	// gh resolves a branch name when it is a PR head ref.
+	const byBranch = await ghPrView(branch);
+	if (byBranch) return byBranch;
+	const inferred = prNumberFromBranchName(branch);
+	if (inferred !== undefined) {
+		const meta = await ghPrView(String(inferred));
+		if (meta) return meta;
+	}
+	fail(`could not resolve a PR for branch '${branch}'; pass --pr <number>`);
+}
+
+const CONVENTIONAL_PREFIX = /^[a-z]+(\([^)]+\))?!?: (.+)$/;
+
+/**
+ * Full mechanically checkable AGENTS.md subject policy: conventional
+ * `type(scope)!:` prefix, ≤72 chars total, description starting lowercase,
+ * no trailing period. (Past tense is not machine-checkable.)
+ */
+export function isCompliantSubject(subject: string): boolean {
+	const m = CONVENTIONAL_PREFIX.exec(subject);
+	if (!m) return false;
+	const desc = m[2];
+	return subject.length <= 72 && !/^[A-Z]/.test(desc) && !desc.endsWith(".");
+}
+
+if (import.meta.main) {
+	const { branch, pr, dryRun } = parseArgs(process.argv.slice(2));
+
+	// Prefer the local ref; fall back to the remote-tracking ref when the branch
+	// was never checked out locally.
+	let mergeRef = branch;
+	const refCheck = await $`git rev-parse --verify --quiet ${branch}`.quiet().nothrow();
+	if (refCheck.exitCode !== 0) {
+		const remoteCheck = await $`git rev-parse --verify --quiet origin/${branch}`.quiet().nothrow();
+		if (remoteCheck.exitCode !== 0) fail(`'${branch}' is neither a local nor an origin/ ref`);
+		mergeRef = `origin/${branch}`;
+		console.warn(`note: '${branch}' is not local; merging '${mergeRef}'`);
+	}
+
+	const meta = await resolvePr(branch, pr);
+
+	// Subject comes from the first (oldest) fully compliant commit being
+	// merged; if none complies, refuse to merge.
+	const log = await $`git log --reverse --format=%s HEAD..${mergeRef}`.quiet().nothrow();
+	if (log.exitCode !== 0) fail(`git log HEAD..${mergeRef} failed`);
+	const subjects = log
+		.text()
+		.split("\n")
+		.map(s => s.trim())
+		.filter(Boolean);
+	if (subjects.length === 0) fail(`'${branch}' has no commits ahead of HEAD`);
+	const subject = subjects.find(isCompliantSubject);
+	if (!subject) fail(`no compliant commit subject in HEAD..${mergeRef}; the merge message cannot comply with the schema`);
+	const message = `Merge PR #${meta.number}: ${subject} (@${meta.author.login})`;
+
+	if (dryRun) {
+		console.log(message);
+		process.exit(0);
+	}
+
+	const merge = await $`git merge --no-ff -m ${message} ${mergeRef}`.nothrow();
+	process.exit(merge.exitCode);
+}