nyaruka/phonenumbers is a Go implementation of Google's libphonenumber, a library that parses and validates telephone numbers using international numbering metadata. It is used in software that needs to interpret phone numbers from different countries, and its catalogue skill supports synchronizing the port with upstream changes.
Borrowing it
Nothing to install: this file belongs to nyaruka/phonenumbers. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/nyaruka/phonenumbers/main/.claude/skills/sync-upstream/SKILL.mdgit clone --depth 1 https://github.com/nyaruka/phonenumbersWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/nyaruka/phonenumbers/sync-upstream)<a href="https://agentmods.dev/skills/nyaruka/phonenumbers/sync-upstream"><img src="https://agentmods.dev/badge/skills/nyaruka/phonenumbers/sync-upstream/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/nyaruka/phonenumbers/sync-upstream"><img src="https://agentmods.dev/badge/skills/nyaruka/phonenumbers/sync-upstream.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00098 | $0.02609 |
| Opus 5.5 | $0.00039 | $0.01044 |
| Sonnet 5.5 | $0.00020 | $0.00522 |
| Haiku 4.5 | $0.00010 | $0.00261 |
Grade A, and why
sync-upstream scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 196 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Sync with upstream libphonenumber
This package is a Go port of google/libphonenumber, tracking its Java reference implementation. A sync has two phases — run them in order:
- Metadata regen — mechanical. Rebuild the embedded
data/blobs from a new upstream release. Fully automated bycmd/buildmetadata. - Code reconciliation — judgment. Port new Java logic changes into the Go files. Can't be automated; this is the real reason SYNC.md exists.
State lives in SYNC.md: the upstream version the port is synced against
and the deliberate divergences (what we intentionally do not port). Read it first. The
generated metadata/version.go (metadata.Version) records the same version — never hand-edit
that.
Run everything from the repo root (/Users/rowan/nyaruka/phonenumbers).
This skill never releases — no tag, no push, no CHANGELOG.md. Releases are cut
separately after reviewing the sync.
Phase 1 — Metadata regen (mechanical)
go run ./cmd/buildmetadata # latest upstream release
# go run ./cmd/buildmetadata v9.0.32 # or pin a specific tag
This resolves the target tag, wipes and re-clones upstream into _build/ (a shallow
--depth=1 checkout at the target tag — gitignored), rebuilds every embedded blob
(data/, metadata/data/, carrier/data/, geocoding/data/, timezone/data/), and
rewrites the generated metadata/version.go with the tag it built from.
Then:
go test ./...
Review the diff — include untracked files (git status not just git diff), since a new
upstream locale or prefix file produces a new blob. The only files that may change or appear
are the embedded blobs (data/, metadata/data/, carrier/data/, geocoding/data/,
timezone/data/) and the generated metadata/version.go:
- No changes at all → the metadata is already up to date; continue to Phase 2 (the code baseline may still lag the metadata version).
- Changes outside that set → something is wrong; stop and report the unexpected changes without committing.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 10d ago Changed · -18 lines · -26 tokens per session 857966719a0f
- 2mo ago First seen · 214 lines · 124 tokens per session scan A b2193c689ddf
sync-upstream is a skill published in the GitHub repository nyaruka/phonenumbers (1,608 stars, last pushed 11d ago), licensed MIT. It adds 98 tokens to every session and 2,609 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
sync-upstream compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| sync-upstreamnyaruka/phonenumbers | Skill | 1.6k | 11d ago | MIT | A | 98 | Claude Code |
| golang-testingaffaan-m/ECC | Skill | 298k | 4d ago | MIT | A | 37 | Claude Code, Kiro |
| golang-patternsaffaan-m/ECC | Skill | 298k | 4d ago | MIT | A | 45 | Claude Code, Kiro |
| golang-testingsamber/cc-skills-golang | Skill | 3.8k | 5d ago | MIT | A | 115 | Claude Code |
| golang-uber-fxsamber/cc-skills-golang | Skill | 3.8k | 5d ago | MIT | A | 122 | Claude Code |
| golang-samber-oopssamber/cc-skills-golang | Skill | 3.8k | 5d ago | MIT | A | 74 | Claude Code |
| ax-go-agent-optimizeax-llm/ax | Skill | 3.0k | 3d ago | Apache-2.0 | A | 51 | Claude Code, Codex |