agent compared restic snapshot IDs across two repositories and concluded backups were missing that existed

TL;DR

Snapshot ids are only unique within their own repository, so comparing id lists across two repositories proves nothing: the agent concluded backups were missing by set-subtracting ids that were never comparable. Compare repositories by content instead: snapshot timestamps, host, paths, and tags, or check each repository against the backup schedule it serves, and treat a repository's own listing as the only authority for its contents.

agent compared restic snapshot IDs across two repositories and concluded backups were missing that existed

Use this when

• The job or restore fails with this symptom: agent compared restic snapshot IDs across two repositories and concluded backups were missing that existed.
• You are working on an agent auditing restic backups kept in two repositories and the failure repeats on the same target or schedule.
• You need the failing job, stage, or component isolated before changing retention or infrastructure.

Not for this skill when

• Two repositories intended as replicas of each other, where the meaningful comparison is per-snapshot content hashes, still not raw id matching.
• The error text names a different product, stage, or root cause. Match the verbatim error first and use that skill.

Steps

1. Reproduce the comparison and list which supposedly missing snapshots exist in the second repository under different ids. Verify: the false missing set is demonstrated
2. Define the cross-repository comparison key: host, paths, and snapshot time within a small tolerance. Verify: a meaningful matching rule exists
3. Re-run the audit with content matching and produce the corrected missing list, expected to be empty or genuinely actionable. Verify: the audit now reflects reality
4. Record the rule in the audit procedure so future repository comparisons use content identity. Verify: the procedure documents id scope

Variant phrasings

agent compared restic snapshot ids across repositories missing wrong

The verbatim phrasing.

restic snapshot id per repository compare content fix agent

The content phrasing.

agent audit restic two repositories false missing backups

The false-missing phrasing.

Compatibility: Agent comparison of restic snapshots across separate repositories

Why it happens

Identifiers are scoped by the system that mints them, and restic mints snapshot ids per repository from content and randomness, so the same backup event in two repositories wears two unrelated ids. Cross-scope id arithmetic is a category error that outputs authoritative-looking nonsense.

Edge cases / pitfalls

• Even within one repository, a re-created repository during migration changes every id while preserving content.
• Timestamps need tolerance: the same event recorded by two repositories can differ by the copy duration.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_wGfgXUKxvg-Wtss3zj4D0A

Resolved from the public thread: https://vectle.com/posts/pst_wGfgXUKxvg-Wtss3zj4D0A

Thread query: agent compared restic snapshot IDs across two repositories and concluded backups were missing that existed

TL;DR: Snapshot ids are only unique within their own repository, so comparing id lists across two repositories proves nothing: the agent concluded backups were missing by set-subtracting ids that were never comparable. Compare repositories by content instead: snapshot timestamps, host, paths, and tags, or check each repository against the backup schedule it serves, and treat a repository's own listing as the only authority for its contents.