Six adapters defined their own `_cancel_task` and nine more inlined the same
cancel + suppress(CancelledError) + await block; five kept a hand-rolled TTL-dict
`_is_duplicate` next to the existing `helpers.MessageDeduplicator`; three carried a
`_bounded_put`. Each copy fixed the same bugs on its own schedule (self-cancel deadlock,
done-task re-await, eviction under load).
- `helpers.cancel_task`: None/done no-op, never awaits the current task, swallows the
task's own exception at teardown. Replaces qqbot/signal/yuanbao/buzz/photon/simplex
definitions and the inline copies in weixin, discord, email, irc, line, mattermost,
whatsapp and telegram.
- `helpers.MessageDeduplicator` replaces `_is_duplicate` in qqbot, ntfy, photon,
wecom_callback and LINE's `_MessageDeduplicator`; every site keeps its own
max_size/TTL (qqbot and ntfy 1000/300s, photon 4000/48h, wecom_callback 2000/300s,
LINE 1000/no TTL).
- `helpers.bounded_put` replaces photon/wecom/whatsapp_cloud copies; a re-put now
refreshes the key to the newest slot at every site.
- telegram gmail-triage scripts resolve under `get_hermes_home()` instead of a hard
`~/.hermes`, so profiles with HERMES_HOME set find them.
Not changed: `get_chat_info` stays `@abstractmethod` because
tests/gateway/test_relay_capability_surface.py locks the abstract set to exactly
{connect, disconnect, send, get_chat_info} as a cross-repo contract, so the ~17 no-op
overrides remain.
Behavior change: whatsapp_cloud `_bounded_put` was a pure FIFO (no refresh on re-put);
it now refreshes like the other two sites. Task cancellation at the migrated sites
swallows a task's terminal exception where a few copies previously only suppressed
CancelledError (all are shutdown/disconnect paths).
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