Spaces:

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ml-intern-explorers

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whatsapp-bot

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Running

Bug Report: Internal Server Error on Hugging Face Spaces

Two bugs in main.py were causing the 500 Internal Server Error.

Bug 1: Unescaped CSS braces in DASHBOARD_HTML (primary cause)

The DASHBOARD_HTML string is rendered using Python's .format() method, which treats any { and } in the string as template variable placeholders. The HTML template is full of CSS rules like * { margin: 0; padding: 0; }, body { font-family: ... }, and so on. Python tries to look these up as named variables and immediately raises a KeyError, crashing the GET / dashboard route with a 500.

The fix is to escape every CSS brace as {{ and }} throughout the template string, while leaving the actual template variables (e.g. {messages_received}, {messages_html}) as single braces. Python's .format() then treats {{ as a literal { in the output.

Bug 2: Deprecated @app.on_event("startup") decorator

The startup logic uses @app.on_event("startup"), which was deprecated in FastAPI 0.93 and can cause warnings or failures depending on the FastAPI/uvicorn version deployed in the Space. HF Spaces tends to use recent package versions, which makes this a real risk.

The fix is to replace it with the modern lifespan context manager pattern an async generator decorated with @asynccontextmanager, passed as lifespan= to FastAPI(...). The startup logic runs before yield, and any shutdown logic would go after. The lifespan function also needs to be defined before app = FastAPI(...) is called, since it's passed in at instantiation time.

Both fixes have been validated: the module loads cleanly, and DASHBOARD_HTML.format(...) now works without errors.