chore(labels): run the legacy label cleanup across the organization

[ss-o]

Tracks the execution that #465 and PR #466 deliberately left out of scope. The tooling is the PR; running it is this issue.

Blocked on

• PR feat(labels): add gated migrate and delete paths to labels-sync.rb #466 merged
• Explicit maintainer approval for the run, with figures re-measured at run time

Measured scope (2026-07-21, will need re-measuring)

Across 86 active, public, non-fork repositories, counting every issue and pull request in any state:

Operation	Count
Unused legacy labels to delete	1,405
In-use legacy labels to migrate	60 (repo, label) pairs
Items to relabel before those deletions	1,002 across 31 repos
Unknown labels	1,503 — never deleted, delete_unknown_labels: false

Roughly 2,400 irreversible write operations. dependencies 📦 → area:dependencies alone accounts for 754 items across 18 repos.

Why the figures must be re-measured

The counts above come from a point-in-time sweep. Labels gain items continuously, and a label that reads as unused today may not be tomorrow. The tooling measures usage live per repo, so a stale plan is not itself dangerous — but the approval should be given against real numbers, not these.

Suggested sequence

1. Re-run the read-only audit and post current figures here
2. Pilot on a single low-traffic repository, verify the result by hand
3. Migrate in-use labels before deleting unused ones, so a mid-run abort leaves the safer state
4. Batch by repository, not by label, so a failure is contained
5. Archive the before-state and the per-repo result, as was done for the canonical rollout

Cautions

• The canonical set contains both dependencies (the Dependabot and Renovate auto-applied label) and area:dependencies. Only the emoji-suffixed dependencies 📦 is legacy. Do not touch the bare dependencies.
• labels-sync.rb has no rate-limit backoff and returns early on first error per repo. Expect to re-run to converge.
• Two labels.yml files have drifted; docs cite the stale one #461 (two labels.yml files have drifted) should land first — deleting against the wrong source of truth would be difficult to undo.

Related

• feat(labels): add gated migrate and delete paths to labels-sync.rb #465 — tooling
• feat(labels): add gated migrate and delete paths to labels-sync.rb #466 — implementation PR
• Two labels.yml files have drifted; docs cite the stale one #461 — labels.yml drift, should resolve first