Generalize email domain handling in documentation and tests (#27)

* Generalize email domain handling in documentation and tests

- Add .worktrees/ to .gitignore for git worktree support
- Update _sanitize_email_for_username docstring to be domain-agnostic
- Change CLAUDE.md example from trailofbits.com to example.com
- Add tests for google.com, gmail.com, corporate, and plus addressing

The code already supported any email domain; this updates docs and
tests to reflect that capability.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Address PR review comments

- Remove redundant trailofbits.com regex, simplify to split("@")[0]
- Rename test to clarify backwards compatibility intent

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Co-authored-by: Dan Guido <dan@trailofbits.com>

.gitignore

@@ -11,3 +11,6 @@ dropkit/_version.txt
 
 # Virtual environments
 .venv
+
+# Git worktrees
+.worktrees/

CLAUDE.md

@@ -55,7 +55,7 @@ dropkit/
 ### Username
 - **Derived from DigitalOcean account email**, not configured
 - Fetched via `/v2/account`, sanitized for Linux compatibility
-- `john.doe@trailofbits.com` → `john_doe`
+- `john.doe@example.com` → `john_doe`
 
 ### SSH Hostname
 - All SSH entries use `dropkit.<droplet-name>` format

dropkit/api.py

@@ -117,9 +117,10 @@ class DigitalOceanAPI:
     @staticmethod
     def _sanitize_email_for_username(email: str) -> str:
         """
-        Sanitize email address to create a valid username.
+        Sanitize email address to create a valid Linux username.
 
-        Removes @trailofbits.com suffix and replaces special characters.
+        Extracts the local part (before @) and replaces special characters
+        with underscores. Ensures the result is a valid Linux username.
 
         Args:
             email: Email address from DigitalOcean account
@@ -127,12 +128,8 @@ class DigitalOceanAPI:
         Returns:
             Sanitized username suitable for Linux user creation
         """
-        # Remove @trailofbits.com suffix (case insensitive)
-        username = re.sub(r"@trailofbits\.com$", "", email, flags=re.IGNORECASE)
-
-        # If no @trailofbits.com, just take the part before @
-        if "@" in username:
-            username = username.split("@")[0]
+        # Extract local part (before @)
+        username = email.split("@")[0]
 
         # Replace dots, hyphens, and other special characters with underscores
         username = re.sub(r"[^a-z0-9_]", "_", username.lower())

tests/test_api.py

@@ -8,8 +8,8 @@ from dropkit.api import DigitalOceanAPI
 class TestDigitalOceanAPI:
     """Tests for DigitalOceanAPI class."""
 
-    def test_sanitize_email_for_username_trailofbits(self):
-        """Test sanitizing trailofbits.com email."""
+    def test_sanitize_email_for_username_trailofbits_backwards_compat(self):
+        """Test backwards compatibility: trailofbits.com emails still work."""
         username = DigitalOceanAPI._sanitize_email_for_username("john.doe@trailofbits.com")
         assert username == "john_doe"
 
@@ -33,6 +33,26 @@ class TestDigitalOceanAPI:
         username = DigitalOceanAPI._sanitize_email_for_username("@trailofbits.com")
         assert username == "user"
 
+    def test_sanitize_email_for_username_google(self):
+        """Test sanitizing google.com email."""
+        username = DigitalOceanAPI._sanitize_email_for_username("jane.smith@google.com")
+        assert username == "jane_smith"
+
+    def test_sanitize_email_for_username_gmail(self):
+        """Test sanitizing gmail.com email."""
+        username = DigitalOceanAPI._sanitize_email_for_username("user123@gmail.com")
+        assert username == "user123"
+
+    def test_sanitize_email_for_username_corporate(self):
+        """Test sanitizing corporate email with subdomain."""
+        username = DigitalOceanAPI._sanitize_email_for_username("dev.ops@corp.company.com")
+        assert username == "dev_ops"
+
+    def test_sanitize_email_for_username_plus_addressing(self):
+        """Test sanitizing email with plus addressing (any domain)."""
+        username = DigitalOceanAPI._sanitize_email_for_username("user+tag@outlook.com")
+        assert username == "user_tag"
+
 
 class TestValidatePositiveInt:
     """Tests for _validate_positive_int method."""