REPO PACKAGE
facebook hermes
OFFICIAL5skills
1ready to use
LABSCO SUMMARY
Four of the five are specific to Hermes's own internals: add-ir-instruction walks through wiring a new IR instruction into the compiler, gc-safe-coding sets rules for writing GC-safe C++ against Hermes's managed types (HermesValue, Handle, GCScope, and the rest), modify-jsi-features covers adding a method to the JSI runtime interface across its core, Hermes implementation, and SynthTrace replay layers, and binary-size-analysis measures how a range of commits changed hermesvm's binary size. The fifth, non-interactive-git-rebase, is a generic git-history skill for reordering, splitting, or amending commits without an interactive editor — useful to any contributor, but it has nothing Hermes-specific in it and would work unchanged in any other repository.
This is not for someone building a React Native app. Hermes's own readme says as much: if you only want pre-built Hermes inside an RN app, you don't need to follow its build guide at all — these five skills assume you're compiling Hermes from source and changing its C++ internals, which is a small slice of everyone who ends up running Hermes.
READ THE FULL ANALYSIS
What it costs to use one. Only modify-jsi-features is labelled ready to run with no setup. The other four need either a local tool — a working Hermes/hermesvm build, or a git checkout with the right history — or are unverified in our data, meaning we have not independently confirmed what they assume. None depend on an account or an external service; the real cost here is a working C++ build of Hermes, not a subscription.
WHAT'S INSIDE
5 showing · 5 totalReady to use
Nothing else to set up — install it and go.
5 of 5
SETUP
Showing all 5 skills
add-ir-instruction
Adding one new instruction to the Hermes JavaScript compiler means editing a dozen files in step — the documentation, the checks, the type handling, three separate code generators and the tests — and this walks through every one of them in order.
binary-size-analysis
Works out which change in a stretch of the project's history made the Hermes engine bigger, by rebuilding at each one and measuring, then writes up the largest jumps with a breakdown of where the extra size went.
gc-safe-coding
The Hermes engine reclaims unused memory behind your back, and a reference the surrounding C++ code was holding can go stale the instant it does; these are the rules for writing code that survives that, and for spotting code that won't.
modify-jsi-features
There is one shared interface through which C++ code drives any JavaScript engine, and this adds a new call to it: a plain version that works everywhere, a faster Hermes-specific one, and the record-and-replay support that debugging depends on.
non-interactive-git-rebase
Rewriting a project's history normally means hand-editing a list in a text editor; this does the same reordering, dropping, splitting and amending from a script instead, and always leaves a safety copy of the original behind first.
No skill in this package matches that.
HOW TO GET IT
WHOLE PACKAGEInstall the whole package (5 skills)
npx skills add facebook/hermesSINGLE SKILLOr install a single skill
npx skills add facebook/hermes --skill <name> --full-depthPick the skill name from the Skills tab — each entry there installs independently.