Fix Telegram client startup under uvicorn in Docker

[akang943578]

Summary

Fixes #5 — backend bot client fails on Docker startup with Future attached to a different loop.

• Defer Pyrogram Client creation until FastAPI lifespan runs (binds to uvicorn's event loop)
• Import bot handlers after clients are built
• Use telegram.tg_client in auth/streaming routers to avoid stale None imports
• Mount session volume at /app/session instead of /app so image rebuilds are not masked

Test plan

• docker compose up -d --build on clean volume
• Backend starts without asyncio loop error
• GET /api/auth/bot/info returns bot username
• Bot /start and file upload (requires storage channel admin setup)

Made with Cursor

Summary by CodeRabbit

• Bug Fixes

  • Improved app startup reliability by avoiding early initialization issues.
  • Made authentication and streaming more stable when connecting to Telegram services.
  • Fixed session storage so updates persist without hiding the rest of the app.

• Chores

  • Updated container storage settings for cleaner, safer persistence.

[coderabbitai]

📝 Walkthrough

Walkthrough

Telegram client pool construction is moved from module-import time into a new build_clients() function called during app startup. Bot handler registration is deferred until after the pool exists. Routers switch from direct tg_client imports to telegram.tg_client module references. The Docker volume mount is narrowed from /app to /app/session.

Lazy Telegram Client Initialization

Layer / File(s)	Summary
Lazy build_clients() and deferred handler registration backend/app/telegram.py, backend/app/main.py	Top-level eager client pool construction is replaced by build_clients(), which creates the session directory, populates clients, and sets tg_client. start_telegram_client() calls build_clients() then imports bot to register handlers. The side-effect bot import is removed from main.py.
Routers updated to use module-level tg_client reference backend/app/routers/auth.py, backend/app/routers/streaming.py	Both routers switch from from ..telegram import tg_client to from .. import telegram, accessing telegram.tg_client so they always read the lazily assigned module attribute at call time.
Docker volume mount scoped to /app/session docker-compose.yml	telegram_session volume is mounted at /app/session instead of /app, with an added comment explaining that mounting over /app hides rebuilt backend code.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐇 No more loops in a tangle at dawn,
The client pool waits till the server is on.
Session files tucked in their tidy new place,
Handlers now register with startup-time grace.
A Future attached? Not today — hop along! 🎉

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: fixing Telegram client startup in Docker under uvicorn.
Linked Issues check	✅ Passed	Clients are now built during FastAPI lifespan on uvicorn's loop, which addresses the loop-mismatch startup failure in #5.
Out of Scope Changes check	✅ Passed	The router updates, handler import move, and session mount change all support the startup fix and stay within scope.
Docstring Coverage	✅ Passed	Docstring coverage is 88.89% which is sufficient. The required threshold is 80.00%.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@backend/app/routers/streaming.py`:
- Around line 153-156: The thumbnail fallback in the streaming route is
swallowing all `download_media(...)` exceptions, which turns real
client/session/API errors into a misleading later “Thumbnail not found”
response. Update the exception handling in the thumbnail retrieval logic in
`streaming.py` to only suppress the expected not-found case, and add logging for
unexpected failures instead of using a bare `pass`. Keep the fix localized
around the `telegram.tg_client.download_media(...)` fallback path and the
surrounding response handling.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 8cea2854-c397-4f8f-999d-53ccae561bf4

📥 Commits

Reviewing files that changed from the base of the PR and between 742a7a1 and 58e393c.

📒 Files selected for processing (5)

• backend/app/main.py
• backend/app/routers/auth.py
• backend/app/routers/streaming.py
• backend/app/telegram.py
• docker-compose.yml

💤 Files with no reviewable changes (1)

• backend/app/main.py

[coderabbitai]

🩺 Stability & Availability | 🟡 Minor | ⚡ Quick win

Don’t turn fallback download failures into a fake 404.

Lines 153-156 swallow every download_media(...) failure, so client/session/API problems are silently converted into the later “Thumbnail not found” path. Please narrow this to the expected not-found case and log unexpected failures instead of pass.

🧰 Tools

🪛 Ruff (0.15.18)

[error] 155-156: try-except-pass detected, consider logging the exception

(S110)

---

[warning] 155-155: Do not catch blind exception: Exception

(BLE001)

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@backend/app/routers/streaming.py` around lines 153 - 156, The thumbnail
fallback in the streaming route is swallowing all `download_media(...)`
exceptions, which turns real client/session/API errors into a misleading later
“Thumbnail not found” response. Update the exception handling in the thumbnail
retrieval logic in `streaming.py` to only suppress the expected not-found case,
and add logging for unexpected failures instead of using a bare `pass`. Keep the
fix localized around the `telegram.tg_client.download_media(...)` fallback path
and the surrounding response handling.

Source: Linters/SAST tools