fix(telegram): add timeout to start_polling() in network error handler

When the connection pool is in a degraded state after
_drain_polling_connections(), start_polling() can hang indefinitely
when both primary and fallback Telegram endpoints are unreachable. The
httpx client may hold a stale socket that neither connects nor times out
within PTB's internal flow, causing the reconnect ladder to stall at
attempt 1/10 forever.

Wrap start_polling() in asyncio.wait_for() with a 30-second timeout so a
hung call raises asyncio.TimeoutError and feeds back into the existing
retry ladder. This unblocks:
- The 10-retry ladder advances to attempt 2, 3, ...
- The heartbeat loop sees _polling_error_task.done() and can trigger recovery
- The reconnect watcher gets the adapter in _failed_platforms

Fixes #59614

plugins/platforms/telegram/adapter.py

@@ -416,6 +416,12 @@ def _rich_normalize_linebreaks(text: str) -> str:
 # reconnect/teardown ladder. This is an internal safety bound (not a user knob),
 # applied identically at every stop() site so no path can hang on a dead socket.
 _UPDATER_STOP_TIMEOUT = 15.0
+# start_polling() can also hang when the connection pool is in a degraded state
+# after _drain_polling_connections(), particularly when both primary and fallback
+# Telegram endpoints are unreachable. Bounding start_polling() prevents the
+# reconnect ladder from stalling indefinitely and allows the heartbeat loop to
+# trigger its own recovery path. Refs: NousResearch/hermes-agent#59614
+_UPDATER_START_TIMEOUT = 30.0
 
 
 class TelegramAdapter(BasePlatformAdapter):
@@ -2072,11 +2078,26 @@ class TelegramAdapter(BasePlatformAdapter):
         try:
             if not app:
                 raise RuntimeError("Telegram application was torn down during reconnect")
-            await app.updater.start_polling(
-                allowed_updates=Update.ALL_TYPES,
-                drop_pending_updates=False,
-                error_callback=self._polling_error_callback_ref,
-            )
+            # Guard start_polling() with a timeout: when the connection pool is
+            # in a degraded state (e.g., after _drain_polling_connections()), the
+            # httpx client may hold a stale socket that neither connects nor times
+            # out within PTB's internal flow. Bounding start_polling() prevents
+            # the reconnect ladder from stalling indefinitely and allows the
+            # heartbeat loop to trigger its own recovery path.
+            # Refs: NousResearch/hermes-agent#59614
+            try:
+                await asyncio.wait_for(
+                    app.updater.start_polling(
+                        allowed_updates=Update.ALL_TYPES,
+                        drop_pending_updates=False,
+                        error_callback=self._polling_error_callback_ref,
+                    ),
+                    timeout=_UPDATER_START_TIMEOUT,
+                )
+            except asyncio.TimeoutError:
+                raise RuntimeError(
+                    "start_polling() timed out — connection pool may be wedged"
+                )
             logger.info(
                 "[%s] Telegram polling resumed after network error (attempt %d)",
                 self.name, attempt,