From 11a08822e6b3bc09e64054b47196066f0c313fe3 Mon Sep 17 00:00:00 2001
From: Eoic <karolis.strazdas@protonmail.com>
Date: Sat, 27 Jun 2026 17:47:51 +0300
Subject: [PATCH] Add public data sync settings endpoint

---
 papyrus/api/routes/sync.py    | 24 +++++++++++++++++++++++-
 papyrus/config.py             |  1 +
 papyrus/schemas/sync.py       | 14 ++++++++++++++
 tests/api/routes/test_sync.py | 20 ++++++++++++++++++++
 4 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/papyrus/api/routes/sync.py b/papyrus/api/routes/sync.py
index 84dfdb3..682fd1c 100644
--- a/papyrus/api/routes/sync.py
+++ b/papyrus/api/routes/sync.py
@@ -9,13 +9,35 @@
 from papyrus.config import get_settings
 from papyrus.core.database import get_db
 from papyrus.core.rate_limit import limiter
-from papyrus.schemas.sync import PowerSyncUploadRequest, PowerSyncUploadResponse
+from papyrus.schemas.sync import (
+    DataSyncSettingsResponse,
+    FileStorageSettings,
+    PowerSyncUploadRequest,
+    PowerSyncUploadResponse,
+)
 from papyrus.services import sync as sync_service
 
 router = APIRouter()
 DBSession = Annotated[AsyncSession, Depends(get_db)]
 
 
+@router.get(
+    "/settings",
+    response_model=DataSyncSettingsResponse,
+    summary="Get public data sync settings",
+)
+async def get_data_sync_settings() -> DataSyncSettingsResponse:
+    """Return public sync capabilities for client custom-server setup."""
+    settings = get_settings()
+    return DataSyncSettingsResponse(
+        data_sync_url=settings.powersync_service_url,
+        file_storage=FileStorageSettings(
+            supported=True,
+            quota_bytes=settings.file_storage_quota_bytes,
+        ),
+    )
+
+
 @router.post(
     "/powersync-upload",
     response_model=PowerSyncUploadResponse,
diff --git a/papyrus/config.py b/papyrus/config.py
index 786eef3..e9c73b7 100644
--- a/papyrus/config.py
+++ b/papyrus/config.py
@@ -60,6 +60,7 @@ class Settings(BaseSettings):
     powersync_token_expire_minutes: int = 5
     powersync_service_url: str = "http://localhost:8081"
     powersync_service_port: int = 8081
+    file_storage_quota_bytes: int = 1_073_741_824
     powersync_jwks_uri: str | None = None
     powersync_source_role: str | None = None
     powersync_source_password: str | None = None
diff --git a/papyrus/schemas/sync.py b/papyrus/schemas/sync.py
index 3bfae0d..7f38509 100644
--- a/papyrus/schemas/sync.py
+++ b/papyrus/schemas/sync.py
@@ -64,3 +64,17 @@ class PowerSyncUploadResponse(BaseModel):
     """Summary of an applied PowerSync upload transaction."""
 
     applied_count: int
+
+
+class FileStorageSettings(BaseModel):
+    """Public file storage capability advertised by this server."""
+
+    supported: bool
+    quota_bytes: int
+
+
+class DataSyncSettingsResponse(BaseModel):
+    """Public sync settings used by clients for custom server discovery."""
+
+    data_sync_url: str
+    file_storage: FileStorageSettings
diff --git a/tests/api/routes/test_sync.py b/tests/api/routes/test_sync.py
index 48a5b5f..164c42c 100644
--- a/tests/api/routes/test_sync.py
+++ b/tests/api/routes/test_sync.py
@@ -9,6 +9,26 @@
 from papyrus.models import SyncBook, User
 
 
+async def test_sync_settings_are_public_and_hide_implementation_details(client: AsyncClient, monkeypatch):
+    """Return public data sync settings for one-URL custom server discovery."""
+    from papyrus.main import settings as app_settings
+
+    monkeypatch.setattr(app_settings, "powersync_service_url", "https://sync.papyrus.test")
+    monkeypatch.setattr(app_settings, "file_storage_quota_bytes", 1_073_741_824)
+
+    response = await client.get("/v1/sync/settings")
+
+    assert response.status_code == 200
+    assert response.json() == {
+        "data_sync_url": "https://sync.papyrus.test",
+        "file_storage": {
+            "supported": True,
+            "quota_bytes": 1_073_741_824,
+        },
+    }
+    assert "powersync" not in response.text.lower()
+
+
 async def test_legacy_sync_routes_are_removed(client: AsyncClient, auth_headers: dict[str, str]):
     """PowerSync is the only supported synchronization contract."""
     assert (await client.get("/v1/sync/status", headers=auth_headers)).status_code == 404