feat(observability): make the stranded-operation reaper visible while idle

[aparajon]

Why this matters

An idle reaper pass is silent by design: it settles nothing, and an instance that loses the election has nothing to report at all. That leaves a healthy steady state indistinguishable from a reaper that stopped ticking — hours of INFO logs answer neither question, and telling the two apart is the first thing an operator needs during an incident.

What it does

• States the reaper's cadence and batch size once at startup, so a later pass count can be read against a known interval.
• Closes each window of passes with one heartbeat line tallying passes run, operations settled, passes that stood down for another instance, and passes that failed.
• Separates the three pass outcomes in that tally, so an operator seeing no settlements can tell whether this instance did the work and found nothing, deferred to the election holder, or was failing outright.

Summarizing a window rather than narrating every pass keeps a healthy reaper to a few lines an hour — quiet enough to leave on, frequent enough that its absence is noticeable.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Adds periodic “heartbeat” observability to the stranded-operation reaper so operators can distinguish a healthy idle reaper from a stalled or unelected one, without logging every pass.

Changes:

• Introduces a heartbeat window that summarizes pass outcomes (ran / not elected / failed) and total operations settled.
• Emits a one-time startup INFO log stating cadence, batch size, and heartbeat window size; upgrades stop logs to INFO.
• Adds unit tests covering heartbeat window behavior and outcome tallies.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
pkg/api/reaper.go	Adds heartbeat aggregation + startup/heartbeat logs; refactors reaper pass to return an outcome and settled count.
pkg/api/reaper_test.go	Adds tests validating heartbeat summary emission, outcome tallies, and window reset behavior.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.