keeper: graceful shutdown and in-flight round draining in watch mode

[karagozemin]

Summary

services/keeper watch mode should handle SIGINT/SIGTERM by finishing any in-flight reveal/settle operation before exiting, instead of terminating mid-transaction.

Motivation

Killing the keeper mid-settle can leave a round in an ambiguous state and require manual recovery.

Acceptance criteria

• Signal handler that stops picking up new rounds and waits for the current one to complete (with a timeout).
• Structured log line on shutdown start/finish.
• Test simulating a shutdown signal during a queued round.
• README note on operational behavior.

[SHEROSE0]

Hi Maintainer,

I've read through the task description and understand the requirements. I'm confident I can work on this issue. Could you kindly assign it to me?

Thank you!

[Bolajiomo99]

Hi team, I'd love to be considered if a slot opens up. I can implement graceful shutdown handlers for SIGINT/SIGTERM inside the keeper service, ensuring in-flight reveal/settle operations drain cleanly before exit. I will build out the round-blocking logic with an operational timeout, incorporate structured shutdown logs, write the signal simulation test, and document the behavior in the README.

[Sheebazz]

@Sheebazz has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I would like to work on this issue. I will implement graceful shutdown handling for the keeper so that it stops accepting new rounds after receiving a termination signal, waits for any in-flight reveal or settlement operation to complete within a defined timeout, adds structured shutdown logging, includes a test covering shutdown during an active round, and updates the documentation to describe the expected operational behavior.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Sheebazz to this issue.

[drips-wave]

Congratulations, @Sheebazz! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @Sheebazz: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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