diff --git a/.gitignore b/.gitignore
index d5db79e..578aa67 100644
--- a/.gitignore
+++ b/.gitignore
@@ -24,3 +24,4 @@ CLAUDE.md
 publish-docker.sh
 .beads
 debug
+backend/.data/
diff --git a/README.md b/README.md
index e413c55..7300cf9 100644
--- a/README.md
+++ b/README.md
@@ -84,6 +84,8 @@ pip install -r requirements.txt
 uvicorn main:app --reload --port 8080
 ```
 
+By default, Docker stores profile data in `/data`. For local development, if `/data` is not writable, the backend falls back to `backend/.data`. You can override this with `CLOAKBROWSER_MANAGER_DATA_DIR=/path/to/data`.
+
 ### Frontend
 
 ```bash
diff --git a/backend/browser_manager.py b/backend/browser_manager.py
index 327f91b..f79c9a3 100644
--- a/backend/browser_manager.py
+++ b/backend/browser_manager.py
@@ -14,7 +14,10 @@
 
 from cloakbrowser import launch_persistent_context_async
 
-from .vnc_manager import VNCManager
+if __package__:
+    from .vnc_manager import VNCManager
+else:  # Support importing browser_manager as a top-level module.
+    from vnc_manager import VNCManager
 
 logger = logging.getLogger("cloakbrowser.manager.browser")
 
@@ -341,7 +344,10 @@ async def cleanup_stale(self):
 
     async def auto_launch_all(self):
         """Launch all profiles with auto_launch=True. Called on startup."""
-        from . import database as db
+        if __package__:
+            from . import database as db
+        else:
+            import database as db
 
         profiles = db.list_profiles()
         auto_profiles = [p for p in profiles if p.get("auto_launch")]
diff --git a/backend/database.py b/backend/database.py
index e468256..5b79f7b 100644
--- a/backend/database.py
+++ b/backend/database.py
@@ -4,6 +4,7 @@
 
 import datetime
 import json
+import os
 import random
 import sqlite3
 import uuid
@@ -11,7 +12,36 @@
 from pathlib import Path
 from typing import Any
 
-DATA_DIR = Path("/data")
+ENV_DATA_DIR = "CLOAKBROWSER_MANAGER_DATA_DIR"
+DOCKER_DATA_DIR = Path("/data")
+LOCAL_DATA_DIR = Path(__file__).resolve().parent / ".data"
+
+
+def _is_usable_data_dir(path: Path) -> bool:
+    """Return True if path can be created and written to."""
+    probe = path / f".write-test-{os.getpid()}"
+    try:
+        path.mkdir(parents=True, exist_ok=True)
+        probe.write_text("ok")
+        probe.unlink(missing_ok=True)
+        return True
+    except OSError:
+        return False
+
+
+def _resolve_data_dir() -> Path:
+    """Resolve the profile data directory for Docker and local development."""
+    configured = os.environ.get(ENV_DATA_DIR)
+    if configured:
+        return Path(configured).expanduser()
+
+    if _is_usable_data_dir(DOCKER_DATA_DIR):
+        return DOCKER_DATA_DIR
+
+    return LOCAL_DATA_DIR
+
+
+DATA_DIR = _resolve_data_dir()
 DB_PATH = DATA_DIR / "profiles.db"
 
 
diff --git a/backend/main.py b/backend/main.py
index 92727a5..9d5179a 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -24,19 +24,34 @@
 import starlette.requests
 from starlette.types import ASGIApp, Receive, Scope, Send
 
-from . import database as db
-from .browser_manager import BrowserManager
-from .models import (
-    ClipboardRequest,
-    LaunchResponse,
-    LoginRequest,
-    ProfileCreate,
-    ProfileResponse,
-    ProfileStatusResponse,
-    ProfileUpdate,
-    StatusResponse,
-    TagResponse,
-)
+if __package__:
+    from . import database as db
+    from .browser_manager import BrowserManager
+    from .models import (
+        ClipboardRequest,
+        LaunchResponse,
+        LoginRequest,
+        ProfileCreate,
+        ProfileResponse,
+        ProfileStatusResponse,
+        ProfileUpdate,
+        StatusResponse,
+        TagResponse,
+    )
+else:  # Support `uvicorn main:app` from the backend directory.
+    import database as db
+    from browser_manager import BrowserManager
+    from models import (
+        ClipboardRequest,
+        LaunchResponse,
+        LoginRequest,
+        ProfileCreate,
+        ProfileResponse,
+        ProfileStatusResponse,
+        ProfileUpdate,
+        StatusResponse,
+        TagResponse,
+    )
 
 logger = logging.getLogger("cloakbrowser.manager")
 logging.basicConfig(level=logging.INFO, format="%(asctime)s %(name)s %(levelname)s %(message)s")
diff --git a/backend/tests/test_browser_manager.py b/backend/tests/test_browser_manager.py
index ba4665e..fe8dfce 100644
--- a/backend/tests/test_browser_manager.py
+++ b/backend/tests/test_browser_manager.py
@@ -218,7 +218,13 @@ def test_allocate_cdp_port_all_occupied_raises():
         for i in range(CDP_PORT_RANGE):
             s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
             s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-            s.bind(("127.0.0.1", BASE_CDP_PORT + i))
+            try:
+                s.bind(("127.0.0.1", BASE_CDP_PORT + i))
+            except OSError:
+                # A real local service may already occupy a port in the range;
+                # that still counts as unavailable to BrowserManager.
+                s.close()
+                continue
             s.listen(1)
             blockers.append(s)
         with pytest.raises(ValueError, match="No free CDP ports"):
diff --git a/backend/tests/test_database.py b/backend/tests/test_database.py
index ef292c5..aad7e3e 100644
--- a/backend/tests/test_database.py
+++ b/backend/tests/test_database.py
@@ -10,6 +10,22 @@
 from backend import database as db
 
 
+# ── data directory resolution ────────────────────────────────────────────────
+
+
+def test_resolve_data_dir_uses_env_override(tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
+    monkeypatch.setenv(db.ENV_DATA_DIR, str(tmp_path))
+
+    assert db._resolve_data_dir() == tmp_path
+
+
+def test_resolve_data_dir_falls_back_to_local(monkeypatch: pytest.MonkeyPatch):
+    monkeypatch.delenv(db.ENV_DATA_DIR, raising=False)
+    monkeypatch.setattr(db, "_is_usable_data_dir", lambda _path: False)
+
+    assert db._resolve_data_dir() == db.LOCAL_DATA_DIR
+
+
 # ── init_db ──────────────────────────────────────────────────────────────────