Fix: Explicitly set proxy for httpx client to prevent connection pool corruption

[bibotai]

Problem

When running behind a proxy (e.g., Clash, V2Ray), the bot's polling loop can get stuck even if HTTP_PROXY/HTTPS_PROXY environment variables are set. The httpx connection pool becomes corrupted after network interruptions, and the bot stops responding to messages while the process is still running.

Root Cause

python-telegram-bot's Application.builder() does not automatically use the HTTP_PROXY/HTTPS_PROXY environment variables for its httpx client. The proxy needs to be explicitly set via builder.proxy().

Solution

Explicitly read proxy from environment variables and pass it to the Application builder:

import os
proxy_url = os.environ.get("HTTPS_PROXY") or os.environ.get("HTTP_PROXY")
if proxy_url:
    builder.proxy(proxy_url)
    logger.info("Proxy configured", proxy=proxy_url)

Testing

• Bot now correctly uses proxy for Telegram API calls
• Polling loop remains stable after network interruptions
• Tested with Clash proxy on macOS

Related Issues

This partially addresses issues where bots stop responding after running for some time behind proxies.

[RichardAtCT]

PR Review
Reviewed head: d837d3f723e4c29dc932532715820648787ed3b9

Summary

• Explicitly passes proxy URL from env vars to Application.builder() to fix connection pool corruption when running behind a proxy (Clash, V2Ray, etc.)

What looks good

• Correct use of builder.proxy() — this is the right PTB API for this
• Sensible env var priority: HTTPS_PROXY before HTTP_PROXY
• Logs when proxy is active, silent when not — good operational behaviour

Issues / questions

1. [Important] src/bot/core.py — import os inside a method body is non-idiomatic; os is almost certainly already imported at the top of this file. Move the import there if not already present.

2. [Important] src/bot/core.py — Logging the full proxy URL (proxy=proxy_url) will expose credentials if the URL contains a username/password (e.g. http://user:pass@host:port). Redact before logging:

   from urllib.parse import urlparse
   parsed = urlparse(proxy_url)
   safe = parsed._replace(password="***").geturl() if parsed.password else proxy_url
   logger.info("Proxy configured", proxy=safe)

3. [Minor] The PR doesn't address the connection pool corruption aspect — it only ensures the proxy is used. If the polling loop truly gets stuck after network interruptions, there may be a separate reconnect/retry issue worth a follow-up ticket.

Test gaps

• No test coverage. At minimum, a unit test that mocks os.environ with HTTPS_PROXY set and asserts builder.proxy() is called would provide a regression guard.

Verdict
⚠️ Merge after fixes — credential leak in logs is a real concern; import os placement is a quick cleanup.

— Friday, AI assistant to @RichardAtCT (posted as @RichardAtCT — FridayOpenClawBot access pending)