[BUG] Celery result backend default Redis DB number (0) does not match config default (1)

[vipul674]

Description of the Bug

There is a mismatch between the default Redis DB number for the Celery result backend in two places:

backend/app/celery_app.py (line ~7):

celery_app = Celery(
    "app.tasks",
    broker=os.getenv("CELERY_BROKER_URL", "redis://localhost:6379/0"),
    backend=os.getenv("CELERY_RESULT_BACKEND", "redis://localhost:6379/0"),  # ← DB 0
)

backend/app/config.py:

CELERY_RESULT_BACKEND: str = "redis://localhost:6379/1"  # ← DB 1

If CELERY_RESULT_BACKEND environment variable is set, both use it consistently. But if neither is set:

• celery_app.py defaults to redis://localhost:6379/0 (DB 0)
• config.py defaults to redis://localhost:6379/1 (DB 1)

This means Celery stores task results in Redis DB 0 while the rest of the application (and any monitoring tools) expect results in DB 1. The celery_app.py is imported and configured before config.py settings take effect in certain code paths.

Steps to Reproduce

1. Start the application without setting CELERY_RESULT_BACKEND environment variable
2. Submit a Celery task
3. Check Redis DB 1 for the task result — it's empty
4. Check Redis DB 0 — the result is stored there

Expected Behavior

Both defaults should use the same Redis DB number. The recommended fix is to align celery_app.py with config.py (use DB 1).

Affected File

backend/app/celery_app.py (line ~7)

Suggested Fix

Change the default in celery_app.py to match config.py:

backend=os.getenv("CELERY_RESULT_BACKEND", "redis://localhost:6379/1"),

Or better, import the default from config to ensure they never diverge.

GSSoC '26

• Yes, I am participating in GirlScript Summer of Code and would like to fix this.

[github-actions]

Hi @vipul674! 👋

Thanks for opening this issue! We are thrilled to have you contribute to PDF-Assistant-RAG for GSSoC 2026.

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• Make sure you have read our Contributing Guidelines.
• Wait for a project admin to assign this issue to you before working on it.
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Happy Coding! 🚀

[vipul674]

@param20h I would like to work on this issue under GSSoC 2026. Please assign it to me.