feat: Multi-tenant per-user data isolation

[khalidnass]

Summary

• Add per-user SurrealDB database isolation via Python contextvar + dynamic db_connection()
• ProxyAuthMiddleware reads X-Forwarded-User header from auth proxy (OAuth2 Proxy + Dex + ADFS/OIDC)
• Controlled by MULTI_TENANT_MODE=true env var — disabled by default, fully backward-compatible
• Zero changes to domain models, routers, services, search, or frontend components

Files Changed (11 files)

Backend (4): user_context.py (new), auth.py, main.py, repository.py
Frontend (2): config/route.ts, use-auth.ts
Tests (3): test_multi_tenant.py (27 tests), test_multi_tenant_e2e.sh (12 tests), config-multitenant.test.ts (4
tests)
Tools (1): mock_auth_proxy.py
Config (1): .gitignore

How it works

1. Request arrives with X-Forwarded-User: alice@company.com
2. ProxyAuthMiddleware sets Python contextvar
3. db_connection() reads contextvar, routes to user_alice_company_com database
4. Migrations run automatically on first request per user

Test plan

• uv run pytest tests/test_multi_tenant.py -v (27 unit tests)
• ./tests/test_multi_tenant_e2e.sh (12 E2E tests)
• npx vitest run src/lib/config-multitenant.test.ts (4 frontend tests)
• uv run pytest tests/ (all 125 tests pass)
• Manual test with mock proxy: different users see isolated data

[cubic-dev-ai]

6 issues found across 11 files

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="mock_auth_proxy.py">

<violation number="1" location="mock_auth_proxy.py:23">
P2: HTTPS upstreams will fail because the proxy always uses HTTPConnection and ignores the upstream URL scheme.</violation>
</file>

<file name="api/auth.py">

<violation number="1" location="api/auth.py:19">
P2: Race condition: concurrent requests for the same user can both pass the `_migrated_users` check and run migrations in parallel because the guard uses a shared set without locking.</violation>
</file>

<file name="tests/test_multi_tenant_e2e.sh">

<violation number="1" location="tests/test_multi_tenant_e2e.sh:73">
P2: List endpoint tests can falsely pass because assert_json_count only checks len(json) without validating a successful status or ensuring the response is a list; a 1-key error object would satisfy expected count=1.</violation>
</file>

<file name="frontend/src/lib/hooks/use-auth.ts">

<violation number="1" location="frontend/src/lib/hooks/use-auth.ts:63">
P2: authRequired can remain null on network errors, causing isLoading to stay true and the UI to remain stuck in a loading state.</violation>
</file>

<file name="open_notebook/database/repository.py">

<violation number="1" location="open_notebook/database/repository.py:36">
P1: Lossy sanitization of user identifiers can map different users to the same database name, breaking per-user isolation.</violation>
</file>

<file name="api/main.py">

<violation number="1" location="api/main.py:115">
P2: ProxyAuthMiddleware trusts X-Forwarded-User without verifying the request came from a trusted proxy, allowing direct clients to spoof the header and impersonate users in multi-tenant mode.</violation>
</file>

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[cubic-dev-ai]

P2: authRequired can remain null on network errors, causing isLoading to stay true and the UI to remain stuck in a loading state.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At frontend/src/lib/hooks/use-auth.ts, line 63:

<comment>authRequired can remain null on network errors, causing isLoading to stay true and the UI to remain stuck in a loading state.</comment>

<file context>
@@ -60,7 +60,7 @@ export function useAuth() {
   return {
     isAuthenticated,
-    isLoading: isLoading || !hasHydrated, // Treat lack of hydration as loading
+    isLoading: isLoading || !hasHydrated || authRequired === null, // Wait for auth check to complete
     error,
     login: handleLogin,
</file context>

[khalidnass]

Fixed in auth-store.ts — network errors now set authRequired: false instead of null

[cubic-dev-ai]

P2: ProxyAuthMiddleware trusts X-Forwarded-User without verifying the request came from a trusted proxy, allowing direct clients to spoof the header and impersonate users in multi-tenant mode.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At api/main.py, line 115:

<comment>ProxyAuthMiddleware trusts X-Forwarded-User without verifying the request came from a trusted proxy, allowing direct clients to spoof the header and impersonate users in multi-tenant mode.</comment>

<file context>
@@ -88,20 +98,23 @@ async def lifespan(app: FastAPI):
+]
+
+if MULTI_TENANT:
+    app.add_middleware(ProxyAuthMiddleware, excluded_paths=_auth_excluded_paths)
+else:
+    app.add_middleware(PasswordAuthMiddleware, excluded_paths=_auth_excluded_paths)
</file context>

[khalidnass]

Added optional PROXY_AUTH_SECRET env var in auth.py — when set, middleware verifies X-Proxy-Auth-Secret header from the proxy

[khalidnass]

@cubic-dev-ai re-review

Fixed remaining issues:

• use-auth.ts: Fixed in auth-store.ts — network errors now set authRequired: false instead of null
• api/main.py: Added optional PROXY_AUTH_SECRET env var in auth.py — when set, middleware verifies
  X-Proxy-Auth-Secret header from the proxy

[cubic-dev-ai]

@cubic-dev-ai re-review

Fixed remaining issues:

• use-auth.ts: Fixed in auth-store.ts — network errors now set authRequired: false instead of null
• api/main.py: Added optional PROXY_AUTH_SECRET env var in auth.py — when set, middleware verifies
  ...

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[cubic-dev-ai]

1 issue found across 12 files

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="mock_auth_proxy.py">

<violation number="1" location="mock_auth_proxy.py:38">
P2: Host header includes ":None" when upstream URL omits a port, producing an invalid Host header that can break upstream routing.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P2: Host header includes ":None" when upstream URL omits a port, producing an invalid Host header that can break upstream routing.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At mock_auth_proxy.py, line 38:

<comment>Host header includes ":None" when upstream URL omits a port, producing an invalid Host header that can break upstream routing.</comment>

<file context>
@@ -0,0 +1,107 @@
+            if key.lower() != "host":
+                headers[key] = val
+        headers["X-Forwarded-User"] = self.server.user
+        headers["Host"] = f"{upstream.hostname}:{upstream.port}"
+        # Force non-chunked response so read() doesn't hang
+        headers["Accept-Encoding"] = "identity"
</file context>