[Starosdev]

Summary

The ZFS collector reports pool status, pool-level error totals and scrub results, but nothing turned them into a notification. Each metrics upload now compares the uploaded pool with the row stored by the previous upload and notifies when the status changed away from ONLINE, an error total grew, or a scrub finished with errors. Sibling of #1127 for Btrfs.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Refactoring (no functional changes)
• CI/CD or infrastructure change

Related Issues

Closes #1130

Changes Made

• notify/zfs.go: ZFSFailureTypes decides which problems are new (or still present, with repeat notifications on) and NewZFSNotify builds the payload. Failure types by severity: ZFSPoolDegraded (any status other than ONLINE, including one unhealthy status worsening to another), ZFSDeviceErrors (pool-level total_read_errors, total_write_errors, total_checksum_errors grew), ZFSScrubErrors (scrub finished with scrub_errors_count above 0, told apart from the previous scrub by scrub_end_time). device_type is ZFS, device_serial is the pool GUID.
• handler/zfs_upload_metrics.go: reads the stored row before RegisterZFSPool, because that call replaces the vdev rows. Muted or archived pools never notify. A read error other than not-found skips the check for that upload. A healthy upload never loads settings.
• handler/state_notify.go: new notifyStateChange holds the mute, settings, repeat and gate handling once; btrfs_upload_metrics.go now calls it instead of its own copy. No behaviour change for Btrfs; its existing tests pass unchanged.
• Docs: new "Notifications" section in docs/ZFS_POOL_MONITORING.md; README feature line mentions ZFS alerts.

Testing

• I have tested this locally
• I have added/updated tests that prove my fix/feature works
• All existing tests pass

go test ./webapp/backend/pkg/notify/ -run 'ZFS|Btrfs' -count=1 and go test ./webapp/backend/pkg/web/handler/ -count=1

• notify: TestZFSFailureTypes (18 cases) and TestNewZFSNotify pass; Btrfs tests unchanged and passing. The full notify package still has the macOS-only TestScriptStreamsOutputAndPreservesEnvironment failure noted in feat(btrfs): notify on degraded filesystems, device errors and scrub errors #1127, unrelated.
• handler: whole package ok (35s), including four new ZFS upload tests: healthy upload loads no settings, muted pool skips, unreadable previous state skips, first upload of a degraded pool delivers one webhook with failure_type=ZFSPoolDegraded after reading the stored row before registering.
• go build ./webapp/backend/... and go vet on both packages clean; gofmt -l reports nothing in the touched files.

Review: not required (lands on develop; reaches users through the promotion PR and release).

Checklist

• My code follows the project's code style
• I have performed a self-review of my code
• I have commented my code where necessary (particularly complex areas)
• I have updated the documentation if needed
• My changes generate no new warnings
• No console.log, debug statements, or commented-out code

Screenshots (if applicable)

N/A

Additional Notes

Vdev-level error matching was left out on purpose: the pool-level totals already move whenever any vdev counter moves, and the notification message points at the pool page for the per-vdev detail.