oxc-project/oxc is a Rust collection of tools for parsing, transforming, resolving, linting, formatting, and minifying JavaScript and TypeScript. It is used to build and maintain JavaScript development and build toolchains. Catalogue add-ons provide workflows for using Oxc tools.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/oxc-project/oxc/insta-snapshotsnpx skills add oxc-project/oxc --skill insta-snapshotsgit clone --depth 1 https://github.com/oxc-project/oxcWrote 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/oxc-project/oxc/insta-snapshots)<a href="https://agentmods.dev/skills/oxc-project/oxc/insta-snapshots"><img src="https://agentmods.dev/badge/skills/oxc-project/oxc/insta-snapshots.svg" alt="Measured on agentmods" 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 | $0.00022 | $0.00938 |
| Opus 5 | $0.00011 | $0.00469 |
| Sonnet 5 | $0.00004 | $0.00188 |
| Haiku 4.5 | $0.00002 | $0.00094 |
Grade A, and why
insta-snapshots 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 6d 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 — 137 lines — stays where its author put it; the contents beside it link to each section on GitHub.
This skill guides you through working with insta snapshot tests in the Oxc codebase without requiring terminal interaction.
What are Insta Snapshots?
Insta is a snapshot testing library for Rust. Oxc uses it extensively for:
- Linter rule tests (
crates/oxc_linter/src/snapshots/) - Semantic analysis tests (
crates/oxc_semantic/tests/integration/snapshots/) - Other crate-specific snapshot tests
Snapshots track expected test outputs (often failures or errors). When code changes, new snapshots are generated as .snap.new files for review.
Running Tests and Generating Snapshots
Run tests for a specific crate:
cargo test -p <crate_name>
This generates .snap.new files if test outputs have changed.
Reviewing Snapshots Non-Interactively
IMPORTANT: Avoid using cargo insta review (the interactive terminal UI). Instead, follow these steps:
1. List all pending snapshots
cargo insta pending-snapshots
# Or for workspace-wide:
cargo insta pending-snapshots --workspace
This shows all .snap.new files waiting for review.
2. Read the snapshot files directly
New snapshots are stored as .snap.new files next to their corresponding .snap files. You can use cargo insta pending-snapshots to view the changes to the snapshot files.
3. Accept or reject changes
Accept all pending snapshots:
cargo insta accept
# Or workspace-wide:
cargo insta accept --workspace
Accept specific snapshot(s):
cargo insta accept --snapshot <snapshot_name>
Reject all pending snapshots:
cargo insta reject
# Or workspace-wide:
cargo insta reject --workspace
This deletes all .snap.new files.
4. Verify the changes
After accepting, the .snap.new files become .snap files. Check with git:
git diff <path/to/snapshots/>
Common Workflows
After fixing a bug or adding new snapshot tests:
- Run tests:
cargo test -p oxc_linter(or relevant crate) - Check pending:
cargo insta pending-snapshots - Read new snapshots to verify they match expected behavior
- Accept if correct:
cargo insta accept - Commit the updated
.snapfiles
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.
- 6d ago First seen · 137 lines · 22 tokens per session scan A a4867aac228a
insta-snapshots is a skill published in the GitHub repository oxc-project/oxc (22,650 stars, last pushed today), licensed MIT. It adds 22 tokens to every session and 938 once invoked, about $0.0001 per session on Opus 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.
Other skills, from other repositories
oxc-docs
Comprehensive reference for the JavaScript Oxidation Compiler (Oxc) — a collection of high-performance JavaScript tools written in Rust. Covers parser design (lexer, AST, parser, errors, semantic analysis), architecture (parser, linter, test infrastructure, AST tools), ECMAScript specification and grammar, performance…
handle-regression
Protocol for detecting, isolating, and fixing regressions in test262 pass count. Use when a test run shows fewer passes than expected.
regression-triage
Bulk-classify a list of test262 pass→other transitions from a CI run. Distinct from handle-regression (single fix) and analyze-regression (diff two runs). Use after a merge wave when the sharded run reports N regressions and you need to bucket them by root cause and decide which are false positives.
merge-wave
Triage N open PRs with sharded test262 results, rank by net pass delta, merge winners, close catastrophes. Use when multiple PRs have completed CI and you want to land a batch.
create-issue
Create a new issue file from a test262 failure pattern. Includes smoke test, sample extraction, and proper frontmatter.
test262-pass-rates
Show current test262 pass rates for both the js-host (gc) and standalone targets side by side, from committed baseline summaries — no network fetch, no compile. Use for a quick conformance status check.