fix(agent): Stop resource watches when users ask

[dcramer]

When Junior starts watching a pull request, it stores a resource subscription
for the current Slack conversation. The bug was that a later message such as
stop could be handled as ordinary chat: Junior would say monitoring stopped,
but the stored subscription could remain active. The existing cancellation tool
also required an internal subscription ID that users never see.

This replaces that model-facing contract with a no-argument
stopWatchingResources action. It cancels every resource watch owned by the
current conversation through the existing bulk-cancellation boundary, and
Junior only confirms after that call succeeds. Stopping everything is
intentional: resource watches are conversation-owned, and the existing Slack
thread opt-out path already uses the same scope.

Creating a watch now returns the exact inverse catalog call, so a later turn can
understand natural requests such as stop without relying on a magic phrase or
rediscovering subscription IDs. Creating subscriptions stays directly
available; the less-common list and stop actions live in the deferred tool
catalog. A regression eval creates a pull-request watch, follows it with
stop, and requires the cancellation action before the confirmation.

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Project	Deployment	Actions	Updated (UTC)
junior-docs	Ready	Preview	Jul 24, 2026 10:03pm

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