fix(phase2): restore agent streams and persist extension installations

backend/app/extensions/installed.py

@@ -0,0 +1,172 @@
+"""Local installation journal. Only explicitly managed ZIP roots may be removed."""
+from __future__ import annotations
+
+import hashlib
+import json
+import logging
+import shutil
+import sqlite3
+import threading
+from contextlib import contextmanager
+from pathlib import Path
+
+from app.extensions.errors import ExtensionError
+
+log = logging.getLogger(__name__)
+
+
+def package_digest(root: Path) -> str:
+    digest = hashlib.sha256()
+    total = 0
+    files = sorted(root.rglob('*'))
+    for path in files:
+        if path.is_symlink():
+            raise ValueError('Package links cannot be restored automatically')
+        if not path.is_file() or '__pycache__' in path.parts or path.suffix == '.pyc':
+            continue
+        total += path.stat().st_size
+        if total > 50 * 1024 * 1024 or len(files) > 4096:
+            raise ValueError('Package exceeds restoration limits')
+        digest.update(path.relative_to(root).as_posix().encode())
+        digest.update(b'\0')
+        digest.update(path.read_bytes())
+    return digest.hexdigest()
+
+
+class InstalledRuntime:
+    def __init__(self, runtime, kind: str, data_dir: Path):
+        self.runtime = runtime
+        self.kind = kind
+        self.storage = (data_dir / 'extension-packages').resolve()
+        self.path = data_dir / 'extension-installations.sqlite3'
+        self.path.parent.mkdir(parents=True, exist_ok=True)
+        self.lock = threading.RLock()
+        self.restoring = False
+        self.restore_errors: list[dict[str, str]] = []
+        with self._db() as db:
+            db.execute('CREATE TABLE IF NOT EXISTS installations (kind TEXT, id TEXT, data TEXT, PRIMARY KEY(kind,id))')
+
+    @contextmanager
+    def _db(self):
+        db = sqlite3.connect(self.path)
+        try:
+            with db:
+                yield db
+        finally:
+            db.close()
+
+    def __getattr__(self, name):
+        return getattr(self.runtime, name)
+
+    def _read(self, identifier):
+        with self._db() as db:
+            row = db.execute('SELECT data FROM installations WHERE kind=? AND id=?', (self.kind, identifier)).fetchone()
+        return json.loads(row[0]) if row else {}
+
+    def _write(self, identifier, data):
+        with self._db() as db:
+            db.execute('INSERT OR REPLACE INTO installations VALUES (?,?,?)', (self.kind, identifier, json.dumps(data)))
+
+    def _save(self, identifier, managed_root=None, *, installing=False):
+        if self.restoring:
+            return
+        record = self.runtime._records[identifier]
+        item = self.runtime.get(identifier)
+        previous = self._read(identifier)
+        self._write(identifier, {
+            'path': str(record.package_path), 'digest': package_digest(record.package_path) if installing or not previous else previous['digest'],
+            'enabled': item.enabled, 'permissions': getattr(item, 'granted_permissions', []),
+            'managed_root': (str(managed_root) if managed_root else None) if installing else previous.get('managed_root'),
+            'removed': False,
+        })
+
+    def install(self, package_path, *, managed_root=None):
+        with self.lock:
+            root = Path(package_path).resolve()
+            package_digest(root)  # Check before changing runtime state.
+            if managed_root is not None:
+                owned = Path(managed_root).resolve()
+                if owned.parent != self.storage or not root.is_relative_to(owned):
+                    raise ValueError('Invalid managed package root')
+            item = self.runtime.install(root)
+            identifier = getattr(item.manifest, f'{self.kind}_id')
+            try:
+                self._save(identifier, managed_root, installing=True)
+            except Exception:
+                self.runtime.uninstall(identifier)
+                raise
+            self.restore_errors = [error for error in self.restore_errors if error['id'] != identifier]
+            return item
+
+    def enable(self, identifier):
+        with self.lock:
+            # Changed packages must be reinstalled to re-parse their declarations.
+            saved = self._read(identifier)
+            root = self.runtime._record(identifier).package_path
+            if saved and saved.get('digest') != package_digest(root):
+                raise ExtensionError('EXTENSION_PACKAGE_CHANGED', 'Package changed; reinstall and review its permissions.', status_code=409)
+            item = self.runtime.enable(identifier)
+            self._save(identifier)
+            return item
+
+    def disable(self, identifier):
+        with self.lock:
+            item = self.runtime.disable(identifier)
+            self._save(identifier)
+            return item
+
+    def set_permissions(self, identifier, permissions):
+        with self.lock:
+            item = self.runtime.set_permissions(identifier, permissions)
+            self._save(identifier)
+            return item
+
+    def uninstall(self, identifier, *args, **kwargs):
+        with self.lock:
+            saved = self._read(identifier)
+            self.runtime.uninstall(identifier, *args, **kwargs)
+            saved['removed'] = True
+            self._write(identifier, saved)
+            self._cleanup(saved)
+
+    def _cleanup(self, saved):
+        raw = saved.get('managed_root')
+        if not raw:
+            return  # Directory installs belong to the user.
+        path = Path(raw)
+        if path.is_symlink() or path.resolve().parent != self.storage:
+            raise ValueError('Refusing to remove an unmanaged package directory')
+        if path.exists():
+            shutil.rmtree(path)
+
+    def restore(self):
+        with self.lock:
+            with self._db() as db:
+                rows = db.execute('SELECT id,data FROM installations WHERE kind=?', (self.kind,)).fetchall()
+            self.restoring = True
+            try:
+                for identifier, raw in rows:
+                    try:
+                        saved = json.loads(raw)
+                        if identifier in self.runtime._records:
+                            self.runtime.uninstall(identifier)
+                        if saved.get('removed'):
+                            self._cleanup(saved)
+                            continue
+                        root = Path(saved['path'])
+                        if not root.is_dir() or package_digest(root) != saved['digest']:
+                            raise ValueError('Package missing or changed; reinstall and review permissions')
+                        item = self.runtime.install(root)
+                        actual_id = getattr(item.manifest, f'{self.kind}_id')
+                        if actual_id != identifier:
+                            self.runtime.uninstall(actual_id)
+                            raise ValueError('Package identity changed')
+                        if self.kind == 'plugin':
+                            self.runtime.set_permissions(identifier, saved.get('permissions', []))
+                        if saved.get('enabled'):
+                            self.runtime.enable(identifier)
+                    except Exception as error:
+                        self.restore_errors.append({'kind': self.kind, 'id': identifier, 'message': 'Package recovery failed; inspect the package and reinstall or enable it again.'})
+                        log.warning('Extension restore failed: %s/%s (%s)', self.kind, identifier, type(error).__name__)
+            finally:
+                self.restoring = False