Merging this PR will not alter performance

✅ 9 untouched benchmarks

_{Comparing FarhanAliRaza:add-backend-path (bc80862) with main (d6db9c9)}

Greptile Summary

This PR adds a backend_path config option (e.g. "/api") that prefixes every backend endpoint (event websocket, /ping, /_upload, /_health, /_all_routes) at both the Starlette mount layer and in the URLs baked into the frontend via env.json (populated through Endpoint.get_url()). It closely mirrors the existing frontend_path pattern, refactoring shared normalization logic into a _prepend_path static helper.

Confidence Score: 5/5

Safe to merge; all remaining findings are style-level P2 suggestions.

The feature is correctly implemented end-to-end: backend_path normalisation is consistent, all five Starlette mount points are updated, Endpoint.get_url() propagates the prefix into env.json so the frontend picks it up automatically, unit tests cover path edge cases and the namespace/mount invariant, and integration tests exercise both the no-prefix and /api cases. No P0/P1 issues found.

Minor: reflex/app.py (inline get_config() in add_all_routes_endpoint) and tests/integration/tests_playwright/test_backend_path.py (rx.App() result not stored as app).

Important Files Changed

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[rxconfig.py\nbackend_path = '/api'] --> B[Config.prepend_backend_path]
    B --> C1[app.py: _setup_state\nmount '/_event' → '/api/_event']
    B --> C2[app.py: _add_default_endpoints\n/ping → /api/ping\n/_health → /api/_health]
    B --> C3[app.py: _add_optional_endpoints\n/_upload → /api/_upload]
    B --> C4[app.py: add_all_routes_endpoint\n/_all_routes → /api/_all_routes]
    B --> C5[Endpoint.get_url\nreturns api_url + /api/endpoint]
    C5 --> D[set_env_json\nbakes prefixed URLs into env.json]
    D --> E[Frontend JS\nreads env.EVENT / env.UPLOAD\nconnects to /api/_event]
    C1 & C2 & C3 & C4 --> F[Starlette routes\nmounted at prefixed paths]
    E -->|WebSocket| F

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