jwx is a Go library implementing JOSE security standards for signing, encrypting, parsing, and verifying JSON-based messages and tokens such as JWTs, JWSs, JWEs, and JWKs. Go developers use it to add authentication and related cryptographic protocols to products, and the catalogue includes guidance for assistants helping developers work with its version 4 API.
Borrowing it
Nothing to install: this file belongs to lestrrat-go/jwx. 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/lestrrat-go/jwx/develop/v4/.claude/skills/jwx-companion-bulk/SKILL.mdgit clone --depth 1 https://github.com/lestrrat-go/jwxWrote 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/lestrrat-go/jwx/jwx-companion-bulk)<a href="https://agentmods.dev/skills/lestrrat-go/jwx/jwx-companion-bulk"><img src="https://agentmods.dev/badge/skills/lestrrat-go/jwx/jwx-companion-bulk/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/lestrrat-go/jwx/jwx-companion-bulk"><img src="https://agentmods.dev/badge/skills/lestrrat-go/jwx/jwx-companion-bulk.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00000 | $0.01923 |
| Opus 5 | $0.00000 | $0.00962 |
| Sonnet 5 | $0.00000 | $0.00385 |
| Haiku 4.5 | $0.00000 | $0.00192 |
Grade A, and why
jwx-companion-bulk 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 12d 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 — 224 lines — stays where its author put it; the contents beside it link to each section on GitHub.
jwx-companion-bulk
Apply a uniform operation across jwx companion modules (github.com/jwx-go/*). Handles cloning, branching, applying changes, verifying, committing, and reporting.
Arguments
/jwx-companion-bulk <instructions...>
$INSTRUCTIONS(required) — what to do across companion modules. Free-form text.
Flags (parsed from instructions)
--modules=<name,name,...>— target only these modules (comma-separated names)--ref-module=<name>— use this module as the reference/template for file-copy operations--pr— push branches and create PRs (off by default; commits locally only)--dry-run— show what would change without modifying anything
If instructions are ambiguous, ask the user before proceeding.
1. Read Config
- Read
companions.yamlfrom the project root. - Parse the
moduleslist. Each entry has:name,repo,branch. - If
--modules=was provided, filter to only those names. Error if a name is not found.
2. Ensure Clones
For each module in the (filtered) list:
-
If
$PROJECT/.companions/repo/<name>/does not exist:cd $PROJECT git clone <repo> .companions/repo/<name> -
If it already exists, update it:
cd $PROJECT/.companions/repo/<name> git fetch origin -
Determine the default branch for each module:
- If
branchis set in the config, use that. - Otherwise, read
origin/HEAD:
This returns e.g.cd $PROJECT/.companions/repo/<name> git symbolic-ref refs/remotes/origin/HEADrefs/remotes/origin/develop/v4— strip the prefix. - If
origin/HEADis not set, query GitHub:gh repo view <org>/<name> --json defaultBranchRef --jq .defaultBranchRef.name
- If
-
Checkout the default branch:
cd $PROJECT/.companions/repo/<name> git checkout <default-branch>cd $PROJECT/.companions/repo/<name> git pull --ff-only
3. Pre-flight Checks
Run these on ALL targeted modules BEFORE modifying ANY:
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.
- 12d ago First seen · 224 lines · 0 tokens per session scan A f8670374c07e
jwx-companion-bulk is a skill published in the GitHub repository lestrrat-go/jwx (2,424 stars, last pushed 4d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,923 tokens. 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.
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