feat(customizations): add removal commands

scripts/lib/remove-instruction.py

@@ -0,0 +1,82 @@
+#!/usr/bin/env python3
+"""Remove the last exact instruction block added to a client overlay."""
+
+import argparse
+import os
+import stat
+import tempfile
+from pathlib import Path
+
+
+def remove_instruction(path: Path, instruction: str) -> bool:
+    if not path.exists():
+        return False
+    if path.is_symlink() or not path.is_file():
+        raise ValueError(f'Instruction path is not a regular file: {path}')
+
+    raw = path.read_bytes()
+    encoding = 'utf-8-sig' if raw.startswith(b'\xef\xbb\xbf') else 'utf-8'
+    lines = raw.decode(encoding).splitlines(keepends=True)
+    wanted = instruction.rstrip('\r\n').splitlines()
+    values = [line.rstrip('\r\n') for line in lines]
+    offset = next((i for i in range(len(values) - len(wanted), -1, -1)
+                   if values[i:i + len(wanted)] == wanted), None)
+    if offset is None:
+        return False
+
+    updated = ''.join(lines[:offset] + lines[offset + len(wanted):])
+    if not updated:
+        path.unlink()
+        return True
+
+    temporary = None
+    try:
+        with tempfile.NamedTemporaryFile(dir=path.parent, prefix='.instruction-', delete=False) as file:
+            temporary = Path(file.name)
+            file.write(updated.encode(encoding))
+        os.chmod(temporary, stat.S_IMODE(path.stat().st_mode))
+        os.replace(temporary, path)
+    finally:
+        if temporary is not None:
+            temporary.unlink(missing_ok=True)
+    return True
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--client', choices=('codex', 'claude', 'both'), required=True)
+    parser.add_argument('--instruction', required=True)
+    parser.add_argument('--home', required=True)
+    args = parser.parse_args()
+    if not args.instruction.strip() or len(args.instruction) > 65536:
+        parser.error('Instruction must contain between 1 and 65536 characters.')
+    home = Path(args.home)
+    if not home.is_absolute():
+        parser.error('Home path must be absolute.')
+    directory = home / '.my-ai-configuration' / 'instructions'
+    if (home / '.my-ai-configuration').is_symlink() or directory.is_symlink():
+        parser.error('Instruction directory must not be a link.')
+    try:
+        inside_home = os.path.commonpath((home.resolve(), directory.resolve())) == str(home.resolve())
+    except ValueError:
+        inside_home = False
+    if not inside_home:
+        parser.error('Instruction directory must remain inside the home directory.')
+
+    targets = ('codex', 'claude') if args.client == 'both' else (args.client,)
+    paths = [(target, directory / f'{target}.md') for target in targets]
+    for _, path in paths:
+        if path.is_symlink():
+            parser.error('Instruction path must not be a link.')
+        if path.exists() and not path.is_file():
+            parser.error('Instruction path must be a regular file.')
+    for target, path in paths:
+        if remove_instruction(path, args.instruction):
+            print(f'Instruction removed for {target}.')
+        else:
+            print(f'Instruction not found for {target}.')
+    return 0
+
+
+if __name__ == '__main__':
+    raise SystemExit(main())