diff --git a/.claude/skills/bump-package-versions/skill.md b/.claude/skills/bump-package-versions/skill.md
new file mode 100644
index 0000000..ffa11dd
--- /dev/null
+++ b/.claude/skills/bump-package-versions/skill.md
@@ -0,0 +1,61 @@
+---
+name: bump-package-versions
+description: Bump the package.json version (patch/minor/major), commit, push, and open a PR.
+---
+
+Bump the package version, commit, push, and open a PR. Do NOT ask for confirmation between steps — just execute.
+
+The user may pass `major`, `minor`, or `patch` as an argument (e.g. `/bump-package-versions patch`). Default to `patch` if no argument is given.
+
+## Step 0: Preflight checks
+
+Run these checks before doing anything. If any fail, abort immediately and tell the user why.
+
+1. **Validate argument.** If an argument is provided, it must be one of `major`, `minor`, or `patch`. If it is anything else, abort with: `Invalid bump type "<arg>". Must be one of: major, minor, patch.`
+2. **Clean working tree.** Run `git status --porcelain`. If there is any output, abort with: `Working tree is not clean. Please commit or stash your changes first.`
+3. **On main branch.** Run `git branch --show-current`. If not on `main`, switch to it with `git checkout main`.
+4. **Up to date with remote.** Run `git pull` to ensure main is current before branching.
+
+## Step 1: Bump the version
+
+1. Read `package.json` and parse the current `version` field.
+2. Increment the version according to the argument:
+   - `patch`: `0.1.1` → `0.1.2`
+   - `minor`: `0.1.1` → `0.2.0`
+   - `major`: `0.1.1` → `1.0.0`
+3. Update the `version` field in `package.json` using the Edit tool. Do not change anything else in the file.
+4. Run `npm i --package-lock-only` to sync `package-lock.json` with the new version.
+5. Store the new version string (e.g. `0.1.2`) for use in later steps.
+
+## Step 2: Create branch, commit, push, and open PR
+
+1. **Create a branch** named `pkg/bump-to-v<NEW_VERSION>` (e.g. `pkg/bump-to-v0.1.2`).
+   Use `git checkout -b <branch>`.
+
+2. **Stage** `package.json` and `package-lock.json`.
+
+3. **Commit** with the message:
+
+   ```
+   pkg: Bump pkg versions to v<NEW_VERSION>
+   ```
+
+   No co-author lines. No multi-line body.
+
+4. **Push** with `git push -u origin <branch>`.
+
+5. **Open PR** with `gh pr create`:
+   - Title: `Bump package version to v<NEW_VERSION>`
+   - Body: `Bumps package version from v<OLD_VERSION> to v<NEW_VERSION>.`
+   - Use a HEREDOC for the body.
+
+6. **Switch back to main** with `git checkout main`.
+
+7. **Return the PR URL** to the user.
+
+IMPORTANT:
+
+- Do NOT amend existing commits
+- Do NOT add untracked files or files unrelated to the version bump
+- Do NOT ask for confirmation at any step
+- Do NOT run build or tests — this is a version-only change
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c6cb43f..f2c9ab3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -40,4 +40,4 @@ jobs:
           BASE_REF="origin/${{ github.base_ref }}"
           HEAD_REF="HEAD"
           echo "Comparing API surface: $BASE_REF..$HEAD_REF"
-          node dist/cli.js "$BASE_REF..$HEAD_REF" --entrypoint src/index.ts || true
+          node dist/cli.js "$BASE_REF..$HEAD_REF" --entrypoint src/index.ts --check
diff --git a/README.md b/README.md
index c933e1c..4164367 100644
--- a/README.md
+++ b/README.md
@@ -33,6 +33,9 @@ npx sigdiff --entrypoint src/index.ts
 
 # JSON output
 npx sigdiff --json
+
+# Exit with code 1 if breaking changes are detected (useful for CI)
+npx sigdiff --check
 ```
 
 ## Example output
@@ -67,6 +70,18 @@ Changes are classified as `major`, `minor`, or `patch` per semver rules.
 | Config required       | None            | Yes                     | Yes                  | Yes             |
 | Git ref comparison    | Any ref         | N/A                     | N/A                  | Baseline file   |
 
+## CI integration
+
+Use `--check` to fail your pipeline when breaking changes are introduced:
+
+```yaml
+# .github/workflows/ci.yml
+- name: API surface check
+  run: npx sigdiff origin/main..HEAD --entrypoint src/index.ts --check
+```
+
+Without `--check`, sigdiff always exits 0 and just prints the diff. With `--check`, it exits 1 if any breaking changes are detected, making it easy to gate PRs.
+
 ## Programmatic API
 
 ```typescript
diff --git a/package-lock.json b/package-lock.json
index 602cfbe..f6a6762 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "sigdiff",
-  "version": "0.1.1",
+  "version": "0.1.2",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "sigdiff",
-      "version": "0.1.1",
+      "version": "0.1.2",
       "license": "MIT",
       "dependencies": {
         "cac": "^6.7.14"
diff --git a/package.json b/package.json
index b807c45..0bb1288 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "sigdiff",
-  "version": "0.1.1",
+  "version": "0.1.2",
   "description": "Changelog from code, not commits. AST-based API surface diffing for TypeScript.",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
diff --git a/src/cli.ts b/src/cli.ts
index d0fda3b..1c135f9 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -14,7 +14,9 @@ cli
   .command('[range]', 'Diff the public API surface between two git refs')
   .option('--entrypoint <path>', 'Scope to a specific file')
   .option('--json', 'Output as JSON instead of markdown')
-  .action((range: string | undefined, options: { entrypoint?: string; json?: boolean }) => {
+  .option('--check', 'Exit with code 1 if breaking changes are detected')
+  .action(
+    (range: string | undefined, options: { entrypoint?: string; json?: boolean; check?: boolean }) => {
     try {
       assertGitRepo();
 
@@ -28,6 +30,10 @@ cli
       const output = format(result, { json: options.json });
 
       process.stdout.write(output);
+
+      if (options.check && result.breaking.length > 0) {
+        process.exit(1);
+      }
     } catch (err) {
       if (err instanceof SigdiffException) {
         process.stderr.write(`Error: ${err.error.message}\n`);
@@ -35,7 +41,8 @@ cli
       }
       throw err;
     }
-  });
+  },
+);
 
 cli.help();
 cli.version(pkgVersion);