
creationix-rx-data-store
Expert skill for using RX, an embedded data store for JSON-shaped data with random-access reads, no-parse lookups, and a text-safe binary encoding format.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/reason-machines/trending-skills --skill creationix-rx-data-store- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads creationix-rx-data-store automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
RX Data Store
Skill by ara.so — Daily 2026 Skills collection.
RX is an embedded data store for JSON-shaped data. Encode once, then query the encoded document in place — no parsing, no object graph, no GC pressure. Think of it as no-SQL SQLite: unstructured data with database-style random access.
Key benefits:
- O(1) array access, O(log n) object key lookup on encoded data
- Automatic deduplication of values and shared schemas
- Text-safe encoding (copy-paste friendly, no binary tooling needed)
- Minimal heap allocations (~10 vs millions for JSON parsing)
- ~18x compression on real deployment manifests (92 MB → 5.1 MB)
Installation
npm install @creationix/rx # library
npm install -g @creationix/rx # CLI (global)
npx @creationix/rx data.rx # CLI (one-off)
Core API
String API (most common)
import { stringify, parse } from "@creationix/rx";
// Encode
const rx = stringify({ users: ["alice", "bob"], version: 3 });
// Returns a string — store it anywhere you'd store JSON text
// Decode (returns a read-only Proxy)
const data = parse(rx) as any;
data.users[0] // "alice"
data.version // 3
Object.keys(data) // ["users", "version"]
JSON.stringify(data) // works — full JS interop
Uint8Array API (performance-critical paths)
import { encode, open } from "@creationix/rx";
const buf = encode({ path: "/api/users", status: 200 });
const data = open(buf) as any;
data.path // "/api/users"
data.status // 200
Inspect API (lazy AST)
import { encode, inspect } from "@creationix/rx";
const buf = encode({ name: "alice", scores: [10, 20, 30] });
const root = inspect(buf);
root.tag // ":"
root[0].tag // "," (a string key)
root[0].value // "name"
root.length // 4 (key, value, key, value)
// Iterate children
for (const child of root) {
console.log(child.tag, child.b64);
}
// Object helpers
for (const [key, val] of root.entries()) { /* ... */ }
const node = root.index("name"); // key lookup → node
const elem = root.index(2); // array index → node
// Filtered key search (O(log n + m) on indexed objects)
for (const [key, val] of root.filteredKeys("/api/")) { /* ... */ }
Escape hatch to underlying buffer
import { handle } from "@creationix/rx";
const h = handle(data.nested);
// h.data: Uint8Array
// h.right: byte offset
Encoding Options
stringify(data, {
// Add sorted indexes to containers with >= N entries (enables O(log n) lookup)
// Use 0 for all containers, false to disable entirely
indexes: 10,
// External refs — shared dictionary of known values for cross-document dedup
refs: { R: ["/api/users", "/api/teams"] },
// Streaming — receive chunks as they're produced
onChunk: (chunk: string, offset: number) => process.stdout.write(chunk),
});
encode(data, {
indexes: 10,
refs: { R: ["/api/users", "/api/teams"] },
onChunk: (chunk: Uint8Array, offset: number) => { /* ... */ },
});
If the encoder used external refs, pass the same dictionary to the decoder:
const data = parse(payload, { refs: { R: ["/api/users", "/api/teams"] } });
const data = open(buf, { refs: { R: ["/api/users", "/api/teams"] } });
CLI
rx data.rx # pretty-print as tree (default on TTY)
rx data.rx -j # convert to JSON
rx data.json -r # convert to RX
cat data.rx | rx # read from stdin (auto-detect format)
rx data.rx -s key 0 sub # select a sub-value: data["key"][0]["sub"]
rx data.rx -o out.json # write to file
rx data.rx --ast # output encoding structure as JSON
rx data.rx -w # write converted file (.json↔.rx)
Full CLI flags:
| Flag | Description |
|---|---|
<file> | Input file (format auto-detected) |
- | Read from stdin explicitly |
-j, --json | Output as JSON |
-r, --rexc | Output as RX |
-t, --tree | Output as tree |
-a, --ast | Output encoding structure |
-s, --select <seg>... | Select a sub-value by path segments |
-w, --write | Write converted file |
-o, --out <path> | Write to file instead of stdout |
-c, --color / --no-color | Force or disable ANSI color |
--index-threshold <n> | Index containers above n values (default: 16) |
--string-chain-threshold <n> | Split strings longer than n (default: 64) |
--string-chain-delimiter <s> | Delimiter for string chains (default: /) |
--key-complexity-threshold <n> | Max object complexity for dedupe keys (default: 100) |
Shell completions:
rx --completions setup zsh # or bash
Tip — paged, colorized viewing:
p() { rx "$1" -t -c | less -RFX; }
Proxy Behavior
The value returned by parse/open is read-only:
obj.newKey = 1; // throws TypeError
delete obj.key; // throws TypeError
"key" in obj; // works (zero-alloc key search)
obj.nested === obj.nested // true (container Proxies are memoized)
Supported operations on the Proxy:
- Property access:
data.key,data[0] Object.keys(),Object.entries(),Object.values()for...of,for...inArray.isArray().map(),.filter(),.find(),.reduce()- Spread and destructuring
JSON.stringify()
Common Patterns
Build-step: convert JSON artifact to RX
import { readFileSync, writeFileSync } from "fs";
import { stringify } from "@creationix/rx";
const json = JSON.parse(readFileSync("manifest.json", "utf-8"));
const rx = stringify(json, { indexes: 10 });
writeFileSync("manifest.rx", rx, "utf-8");
Runtime: sparse read from large RX file
import { readFileSync } from "fs";
import { parse } from "@creationix/rx";
const manifest = parse(readFileSync("manifest.rx", "utf-8")) as any;
// Only the accessed values are decoded — everything else is skipped
const route = manifest.routes["/dashboard/projects"];
console.log(route.title, route.component, route.auth);
Streaming encode to stdout
import { stringify } from "@creationix/rx";
stringify(largeData, {
onChunk: (chunk, offset) => process.stdout.write(chunk),
});
Using external refs for cross-document deduplication
import { stringify, parse } from "@creationix/rx";
const sharedRefs = { R: ["/api/users", "/api/teams", "/api/projects"] };
// Encode multiple documents sharing the same ref dictionary
const doc1 = stringify(data1, { refs: sharedRefs });
const doc2 = stringify(data2, { refs: sharedRefs });
// Decode with the same dictionary
const val1 = parse(doc1, { refs: sharedRefs }) as any;
const val2 = parse(doc2, { refs: sharedRefs }) as any;
Low-level inspect traversal (zero allocation)
import { encode, inspect } from "@creationix/rx";
const buf = encode(routes);
const root = inspect(buf);
// Walk object entries without creating JS objects
if (root.tag === ":") {
for (const [key, val] of root.entries()) {
if (key.value === "/dashboard") {
console.log("Found:", val.index("title").value);
break;
}
}
}
Type-safe usage pattern
import { parse } from "@creationix/rx";
interface Route {
title: string;
component: string;
auth: boolean;
}
interface Manifest {
routes: Record<string, Route>;
version: number;
}
// Cast after parse — RX Proxy supports all read operations
const manifest = parse(rxString) as unknown as Manifest;
const dashboard = manifest.routes["/dashboard"];
Format Reference
RX is a text encoding — not human-readable like JSON, but safe to copy-paste.
Every value is read right-to-left. The parser scans left past base64 digits to find a tag character:
[body][tag][b64 varint]
◄── read this way ──
| JSON | RX | Description |
|---|---|---|
42 | +1k | tag + (integer), b64 1k = 84, zigzag → 42 |
"hi" | hi,2 | tag , (string), length = 2 |
true | 't | tag ' (ref), built-in literal |
[1,2,3] | +6+4+2;6 | tag ; (array), b64 6 = content size |
{"a":1} | +2a,1:a | tag : (object), interleaved keys/values |
Tags: + integer · * decimal · , string · ' ref/literal · : object · ; array · ^ pointer · . chain · # index
When to Use RX vs Alternatives
| Scenario | Use |
|---|---|
| Large artifact, sparse reads | RX |
| Build manifests, route tables | RX |
| Small config files | JSON |
| Human-authored config | JSON/YAML |
| Write-heavy / mutable data | Real database |
| Fixed schema, minimize wire size | Protobuf |
| Relational/tabular data | SQLite |
| Minimizing compressed transfer | gzip/zstd + JSON |
Troubleshooting
TypeError: Cannot set property on decoded value
The Proxy returned by parse/open is read-only by design. To mutate, spread into a plain object first:
const mutable = { ...parse(rx) };
mutable.newKey = "value"; // works
Decoded value looks correct but instanceof Array fails
Use Array.isArray(val) instead — this is correctly intercepted by the Proxy.
External refs mismatch / wrong values decoded
Ensure the exact same refs dictionary (same keys, same arrays, same order) is passed to both stringify/encode and parse/open.
CLI not found after global install
npm install -g @creationix/rx
# If still not found, check your npm global bin path:
npm bin -g
Inspecting encoded bytes
rx data.rx --ast # shows encoding structure with tags and offsets
Or use the live viewer at rx.run — paste RX or JSON directly.
Performance: lookups slower than expected
Ensure indexes threshold is set appropriately when encoding. For large objects (e.g., 35k keys), use indexes: 0 to index all containers:
stringify(data, { indexes: 0 });
Resources
- rx.run — live web viewer, paste RX or JSON to inspect
- docs/rx-format.md — full format spec with grammar and railroad diagrams
- docs/cursor-api.md — low-level zero-allocation cursor API
- samples/ — example datasets (route manifest, RPG state, emoji metadata, sensor telemetry)
FAQ
What does the creationix-rx-data-store skill do?
Expert skill for using RX, an embedded data store for JSON-shaped data with random-access reads, no-parse lookups, and a text-safe binary encoding format.
How do I install creationix-rx-data-store?
Run npx skills add https://github.com/reason-machines/trending-skills --skill creationix-rx-data-store in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/creationix-rx-data-store/ (personal) or .claude/skills/creationix-rx-data-store/ (project).
Which AI agents can use creationix-rx-data-store?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is creationix-rx-data-store safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains creationix-rx-data-store?
It is published by reason-machines in reason-machines/trending-skills. It has 905 recorded installs.
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