v8-optimization Cursor ruleA
v8-optimization from reactive/data-client is a Cursor rule: instructions the Cursor agent follows in that repo.
mdr add reactive/data-client/.cursor/rules/v8-optimization.mdc@git:20261025.7adefeePins git:20261025.7adefee in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 14 of 14 checks passed
- Kind
- Cursor rule
- Repository
- reactive/data-client
- Path
.cursor/rules/v8-optimization.mdc- Versions recorded
- 1
- Latest version
- git:20261025.7adefee, committed Oct 25, 2026
- Size
- 3,463 bytes
- Repository stars
- 2,040
- License
- Apache-2.0
Measure V8 optimization (deopts, inline caches, shapes, inlining) before and after performance-sensitive library changes.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# V8 optimization check When a change to code that runs per entity, per render or per request could change how V8 optimizes it (shapes or property order, call-site polymorphism, `try`/`catch`, `arguments`, `delete`, closures or spreads in loops), spawn a fast subagent to measure base vs change: **Haiku** in Claude Code (Agent tool, `model: "haiku"`), **Grok 4.7 Fast** at medium in Cursor. Give it the changed functions, the base ref, and the suite and filter to run. Skip it for comments, types, strings and renamed locals; renamed object properties do change shapes. | Changed package | Harness | Build each ref first | Can measure | | --- | --- | --- | --- | | normalizr, core, endpoint | `examples/benchmark` | `yarn build:benchmark` (suites import `dist/`) | everything below | | react, rest | `examples/benchmark-react` | `yarn build:benchmark-react`, then `preview` | `bench:trace` (opt/deopt) and `bench:deopt` (`--prof`) only; report the rest as not measured | Measure the base in a separate `git worktree` (run `yarn install` there first), so neither side's checkout or `dist/` is stale. Always pass a narrow filter: unfiltered traces and logs run to many MB. …
Read the whole file at its exact version.
How to install
mdr add reactive/data-client/.cursor/rules/v8-optimization.mdc@sha256:661642939c9f655fThe line at the top of this page pins the label git:20261025.7adefee, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_pb6xi6mygrhwvxe2)
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Versions
The registry has recorded 1 version of this file, committed on Oct 25, 2026.
Audit of the latest version
- pass: Size between 200 bytes and 200 KB (3463 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
reactive/data-client · 2,040 stars · license Apache-2.0 · pushed 2026-11-01 · branch master
API
GET https://markdownregistry.com/api/v1/artifacts/art_pb6xi6mygrhwvxe2 GET https://markdownregistry.com/api/v1/resolve?ref=reactive/data-client/.cursor/rules/v8-optimization.mdc GET https://markdownregistry.com/api/v1/blob/661642939c9f655f7a899a838354db1c0e5b8966d9868fd452e22451070743f5
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Guides: Cursor rules vs AGENTS.md · which agent file does what.