feat(core): add .nx/self-healing to .gitignore (#34855)

## Summary
- Self-healing auto-apply writes fix context to `.nx/self-healing/`, but
that directory was not in `.gitignore`. This adds it via a migration and
in the CAIA generator, following the same pattern as `.nx/polygraph`.

## Current Behavior

The `.nx/self-healing` directory is not gitignored. Users who run
self-healing auto-apply may accidentally commit generated fix context
files.

## Expected Behavior

`.nx/self-healing` is added to `.gitignore` automatically during `nx
migrate` (via a new migration) and when running the CAIA setup
generator.

---------

Co-authored-by: nx-cloud[bot] <71083854+nx-cloud[bot]@users.noreply.github.com>

Author: MaxKless

packages/nx/migrations.json

@@ -160,6 +160,12 @@
       "version": "22.6.0-beta.11",
       "description": "Prompts to enable usage analytics",
       "implementation": "./src/migrations/update-22-6-0/enable-analytics-prompt"
+    },
+    "22-7-0-add-self-healing-to-gitignore": {
+      "cli": "nx",
+      "version": "22.7.0-beta.0",
+      "description": "Adds .nx/self-healing to .gitignore",
+      "implementation": "./src/migrations/update-22-2-0/add-self-healing-to-gitignore"
     }
   }
 }

packages/nx/src/command-line/init/implementation/dot-nx/add-nx-scripts.ts

@@ -89,7 +89,12 @@ export function writeMinimalNxJson(host: Tree, version: string) {
 
 export function updateGitIgnore(host: Tree) {
   let contents = host.read('.gitignore', 'utf-8') ?? '';
-  ['.nx/installation', '.nx/cache', '.nx/workspace-data'].forEach((file) => {
+  [
+    '.nx/installation',
+    '.nx/cache',
+    '.nx/workspace-data',
+    '.nx/self-healing',
+  ].forEach((file) => {
     if (!contents.includes(file)) {
       contents = [contents, file].join('\n');
     }

packages/nx/src/migrations/update-22-2-0/add-self-healing-to-gitignore.md

@@ -0,0 +1,11 @@
+#### Add Self-Healing Directory to Git Ignore
+
+Add gitignore entry for the `.nx/self-healing` directory, which stores local fix context generated by Nx's self-healing CI feature.
+
+#### Sample Code Changes
+
+Adds the following entry to the `.gitignore` file.
+
+```text title=".gitignore"
+.nx/self-healing
+```

packages/nx/src/migrations/update-22-2-0/add-self-healing-to-gitignore.spec.ts

@@ -0,0 +1,88 @@
+import { createTreeWithEmptyWorkspace } from '../../generators/testing-utils/create-tree-with-empty-workspace';
+import { Tree } from '../../generators/tree';
+import addSelfHealingToGitignore from './add-self-healing-to-gitignore';
+
+describe('add-self-healing-to-gitignore migration', () => {
+  let tree: Tree;
+
+  beforeEach(() => {
+    tree = createTreeWithEmptyWorkspace();
+  });
+
+  it('should not create .gitignore if it does not exist', async () => {
+    tree.delete('.gitignore');
+
+    await addSelfHealingToGitignore(tree);
+
+    expect(tree.exists('.gitignore')).toBe(false);
+  });
+
+  it('should add .nx/self-healing to existing .gitignore', async () => {
+    tree.write('.gitignore', 'node_modules\ndist\n');
+
+    await addSelfHealingToGitignore(tree);
+
+    const gitignore = tree.read('.gitignore')?.toString();
+    expect(gitignore).toContain('node_modules');
+    expect(gitignore).toContain('.nx/self-healing');
+  });
+
+  it('should not duplicate if .nx/self-healing is already present', async () => {
+    tree.write('.gitignore', 'node_modules\n.nx/self-healing\n');
+
+    await addSelfHealingToGitignore(tree);
+
+    const gitignore = tree.read('.gitignore')?.toString();
+    const matches = gitignore.match(/\.nx\/self-healing/g);
+    expect(matches).toHaveLength(1);
+  });
+
+  it('should not add if a broader pattern already covers it', async () => {
+    tree.write('.gitignore', '.nx/\n');
+
+    await addSelfHealingToGitignore(tree);
+
+    const gitignore = tree.read('.gitignore')?.toString();
+    expect(gitignore).not.toContain('.nx/self-healing');
+  });
+
+  it('should skip for lerna workspaces without nx.json', async () => {
+    tree.write('.gitignore', 'node_modules\n');
+    tree.write('lerna.json', '{}');
+    tree.delete('nx.json');
+
+    await addSelfHealingToGitignore(tree);
+
+    const gitignore = tree.read('.gitignore')?.toString();
+    expect(gitignore).not.toContain('.nx/self-healing');
+  });
+
+  it('should not skip for lerna workspaces that also have nx.json', async () => {
+    tree.write('.gitignore', 'node_modules\n');
+    tree.write('lerna.json', '{}');
+    // nx.json already exists from createTreeWithEmptyWorkspace
+
+    await addSelfHealingToGitignore(tree);
+
+    const gitignore = tree.read('.gitignore')?.toString();
+    expect(gitignore).toContain('.nx/self-healing');
+  });
+
+  it('should add .nx/self-healing to .prettierignore if it exists', async () => {
+    tree.write('.gitignore', 'node_modules\n');
+    tree.write('.prettierignore', '/dist\n');
+
+    await addSelfHealingToGitignore(tree);
+
+    const prettierignore = tree.read('.prettierignore')?.toString();
+    expect(prettierignore).toContain('.nx/self-healing');
+  });
+
+  it('should not modify .prettierignore if it does not exist', async () => {
+    tree.write('.gitignore', 'node_modules\n');
+
+    await addSelfHealingToGitignore(tree);
+
+    expect(tree.exists('.prettierignore')).toBe(false);
+  });
+});

packages/nx/src/migrations/update-22-2-0/add-self-healing-to-gitignore.ts

@@ -0,0 +1,20 @@
+import { formatChangedFilesWithPrettierIfAvailable } from '../../generators/internal-utils/format-changed-files-with-prettier-if-available';
+import { Tree } from '../../generators/tree';
+import { addEntryToGitIgnore } from '../../utils/ignore';
+
+export default async function addSelfHealingToGitignore(tree: Tree) {
+  if (!tree.exists('.gitignore')) {
+    return;
+  }
+  // Lerna users that don't use nx.json may not expect .nx directory changes
+  if (tree.exists('lerna.json') && !tree.exists('nx.json')) {
+    return;
+  }
+  addEntryToGitIgnore(tree, '.gitignore', '.nx/self-healing');
+
+  if (tree.exists('.prettierignore')) {
+    addEntryToGitIgnore(tree, '.prettierignore', '.nx/self-healing');
+  }
+
+  await formatChangedFilesWithPrettierIfAvailable(tree);
+}