diff --git a/.github/scripts/upsert-breaking-change-comment.cjs b/.github/scripts/upsert-breaking-change-comment.cjs
new file mode 100644
index 000000000..cebc53bb3
--- /dev/null
+++ b/.github/scripts/upsert-breaking-change-comment.cjs
@@ -0,0 +1,71 @@
+/**
+ * Upserts (or removes) a sticky PR comment summarizing breaking commits
+ * detected by `detect-breaking-commits.sh`.
+ *
+ * Invoked via `actions/github-script`. Inputs come from environment vars:
+ *   FOUND          - "true" if the scan found breaking commits
+ *   BREAKING_LIST  - markdown bullet list of breaking commits
+ *   ALLOWED        - "true" if the PR carries the allow-breaking-change label
+ */
+
+const MARKER = "<!-- pr-breaking-change-check -->";
+
+module.exports = async ({ github, context }) => {
+  const { owner, repo } = context.repo;
+  const issue_number = context.issue.number;
+  const found = process.env.FOUND === "true";
+  const allowed = process.env.ALLOWED === "true";
+  const list = process.env.BREAKING_LIST || "";
+
+  const comments = await github.paginate(github.rest.issues.listComments, {
+    owner,
+    repo,
+    issue_number,
+    per_page: 100,
+  });
+  const existing = comments.find((c) => c.body?.includes(MARKER));
+
+  if (!found) {
+    if (existing) {
+      await github.rest.issues.deleteComment({
+        owner,
+        repo,
+        comment_id: existing.id,
+      });
+    }
+    return;
+  }
+
+  const status = allowed
+    ? "> This PR has the `allow-breaking-change` label, so this check will pass. Make sure the next release is intentionally bumped to a major version."
+    : "> Add the **`allow-breaking-change`** label to this PR if the breaking change is intentional, or rewrite the offending commits to remove the `!` / `BREAKING CHANGE:` footer.";
+
+  const body = [
+    MARKER,
+    "### Breaking change detected",
+    "",
+    "This PR contains Conventional Commits breaking-change markers (`type!:` or `BREAKING CHANGE:` footer) in one or more of the following surfaces, all of which feed `release-it` after a squash merge:",
+    "",
+    list.trim(),
+    "",
+    "Merging this PR will force a **major** version bump on the next release (`bumpStrict: true` in `.release-it.json`).",
+    "",
+    status,
+  ].join("\n");
+
+  if (existing) {
+    await github.rest.issues.updateComment({
+      owner,
+      repo,
+      comment_id: existing.id,
+      body,
+    });
+  } else {
+    await github.rest.issues.createComment({
+      owner,
+      repo,
+      issue_number,
+      body,
+    });
+  }
+};
diff --git a/.github/workflows/pr-metadata.yml b/.github/workflows/pr-metadata.yml
new file mode 100644
index 000000000..0fa41941e
--- /dev/null
+++ b/.github/workflows/pr-metadata.yml
@@ -0,0 +1,83 @@
+name: PR Metadata Verification
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened, edited, labeled, unlabeled]
+    branches:
+      - main
+
+permissions:
+  contents: read
+  pull-requests: write
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  check-title:
+    runs-on:
+      group: databricks-protected-runner-group
+      labels: linux-ubuntu-latest
+
+    name: Conventional Commit Title
+    steps:
+      - name: Validate PR title
+        uses: amannn/action-semantic-pull-request@48f256284bd46cdaab1048c3721360e808335d50 # v6.1.1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          types: |
+            feat
+            fix
+            docs
+            test
+            ci
+            refactor
+            perf
+            chore
+            revert
+            style
+            build
+
+  detect-breaking:
+    name: Detect Breaking Commits
+    runs-on:
+      group: databricks-protected-runner-group
+      labels: linux-ubuntu-latest
+    steps:
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
+        with:
+          fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha }}
+
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
+        with:
+          node-version-file: .nvmrc
+
+      - name: Find breaking-change markers
+        id: scan
+        env:
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+          PR_TITLE: ${{ github.event.pull_request.title }}
+          PR_BODY: ${{ github.event.pull_request.body }}
+        # Node 24 strips TS type annotations natively, so no tsx/transpile step needed.
+        run: node tools/detect-breaking-commits.ts
+
+      - name: Upsert sticky PR comment
+        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
+        env:
+          FOUND: ${{ steps.scan.outputs.found }}
+          BREAKING_LIST: ${{ steps.scan.outputs.list }}
+          ALLOWED: ${{ contains(github.event.pull_request.labels.*.name, 'allow-breaking-change') }}
+        with:
+          script: |
+            const upsert = require('./.github/scripts/upsert-breaking-change-comment.cjs');
+            await upsert({ github, context });
+
+      - name: Fail unless explicitly allowed
+        if: steps.scan.outputs.found == 'true' && !contains(github.event.pull_request.labels.*.name, 'allow-breaking-change')
+        run: |
+          echo "::error::Breaking-change commits detected in tracked packages. Add the 'allow-breaking-change' label to bypass, or rewrite the offending commits."
+          exit 1
diff --git a/.github/workflows/pr-title.yml b/.github/workflows/pr-title.yml
deleted file mode 100644
index f1876004a..000000000
--- a/.github/workflows/pr-title.yml
+++ /dev/null
@@ -1,36 +0,0 @@
-name: PR Title
-
-on:
-  pull_request:
-    types: [opened, synchronize, reopened, edited]
-    branches:
-      - main
-
-permissions:
-  pull-requests: read
-
-jobs:
-  check-title:
-    runs-on:
-      group: databricks-protected-runner-group
-      labels: linux-ubuntu-latest
-
-    name: Conventional Commit Title
-    steps:
-      - name: Validate PR title
-        uses: amannn/action-semantic-pull-request@48f256284bd46cdaab1048c3721360e808335d50 # v6.1.1
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        with:
-          types: |
-            feat
-            fix
-            docs
-            test
-            ci
-            refactor
-            perf
-            chore
-            revert
-            style
-            build
diff --git a/knip.json b/knip.json
index 036404ee4..2d234091e 100644
--- a/knip.json
+++ b/knip.json
@@ -23,7 +23,8 @@
     "packages/appkit/src/plugins/agents/load-agents.ts",
     "template/**",
     "tools/**",
-    "docs/**"
+    "docs/**",
+    ".github/scripts/**"
   ],
   "ignoreDependencies": ["json-schema-to-typescript"],
   "ignoreBinaries": ["tarball"]
diff --git a/tools/detect-breaking-commits.ts b/tools/detect-breaking-commits.ts
new file mode 100644
index 000000000..a5896c2ab
--- /dev/null
+++ b/tools/detect-breaking-commits.ts
@@ -0,0 +1,123 @@
+#!/usr/bin/env tsx
+
+/**
+ * Scans for Conventional Commits breaking-change markers in a PR. Three
+ * surfaces are checked, because all three feed `release-it` once the PR is
+ * squash-merged:
+ *
+ *   1. Each commit between $BASE_SHA and $HEAD_SHA, restricted to the
+ *      packages tracked by .release-it.json (avoids docs/tooling-only noise).
+ *   2. The PR title ($PR_TITLE), which becomes the squash commit subject.
+ *   3. The PR description ($PR_BODY), which can land in the squash commit
+ *      body depending on repo settings.
+ *
+ * Writes `found` and (on match) `list` to $GITHUB_OUTPUT. The `list` is a
+ * markdown bullet list, grouping hits by source surface.
+ *
+ * Required env: BASE_SHA, HEAD_SHA, GITHUB_OUTPUT
+ * Optional env: PR_TITLE, PR_BODY
+ */
+
+import { execFileSync } from "node:child_process";
+import { appendFileSync } from "node:fs";
+
+const TRACKED_PATHS = [
+  "packages/appkit",
+  "packages/appkit-ui",
+  "packages/shared",
+];
+
+// Conventional Commits breaking-change markers:
+//   1. `type!:` or `type(scope)!:` in the subject line
+//   2. `BREAKING CHANGE:` or `BREAKING-CHANGE:` footer line
+const BREAKING_PATTERN =
+  /^(feat|fix|chore|refactor|perf|build|ci|docs|style|test|revert)(\([^)]+\))?!:|^BREAKING[ -]CHANGE:/m;
+
+function requireEnv(name: string): string {
+  const value = process.env[name];
+  if (!value) {
+    console.error(`Missing required env var: ${name}`);
+    process.exit(1);
+  }
+  return value;
+}
+
+function git(...args: string[]): string {
+  return execFileSync("git", args, { encoding: "utf8" });
+}
+
+function listCommits(base: string, head: string): string[] {
+  return git("rev-list", `${base}..${head}`, "--", ...TRACKED_PATHS)
+    .split("\n")
+    .map((sha) => sha.trim())
+    .filter(Boolean);
+}
+
+function commitMessage(sha: string): string {
+  return git("log", "-1", "--format=%B", sha);
+}
+
+function commitSubject(sha: string): string {
+  return git("log", "-1", "--format=%s", sha).trim();
+}
+
+function scanCommits(base: string, head: string): string[] {
+  const hits: string[] = [];
+  for (const sha of listCommits(base, head)) {
+    if (BREAKING_PATTERN.test(commitMessage(sha))) {
+      hits.push(`  - \`${sha.slice(0, 7)}\` ${commitSubject(sha)}`);
+    }
+  }
+  return hits;
+}
+
+function scanText(text: string | undefined): boolean {
+  return Boolean(text && BREAKING_PATTERN.test(text));
+}
+
+function writeOutput(found: boolean, list: string): void {
+  const outputPath = requireEnv("GITHUB_OUTPUT");
+  if (!found) {
+    appendFileSync(outputPath, "found=false\n");
+    return;
+  }
+  appendFileSync(
+    outputPath,
+    `found=true\nlist<<COMMITS_EOF\n${list}\nCOMMITS_EOF\n`,
+  );
+}
+
+function main(): void {
+  const base = requireEnv("BASE_SHA");
+  const head = requireEnv("HEAD_SHA");
+  const prTitle = process.env.PR_TITLE;
+  const prBody = process.env.PR_BODY;
+
+  const sections: string[] = [];
+
+  if (scanText(prTitle)) {
+    sections.push(`- **PR title**: \`${prTitle?.trim()}\``);
+  }
+
+  if (scanText(prBody)) {
+    sections.push("- **PR description** contains a breaking-change marker.");
+  }
+
+  const commitHits = scanCommits(base, head);
+  if (commitHits.length > 0) {
+    sections.push(["- **Commits**:", ...commitHits].join("\n"));
+  }
+
+  if (sections.length === 0) {
+    console.log("No breaking-change markers found.");
+    writeOutput(false, "");
+    return;
+  }
+
+  const list = sections.join("\n");
+  console.log("Breaking-change markers found:");
+  console.log(list);
+  writeOutput(true, list);
+}
+
+main();