manager-helpers

Purpose

Small free helpers extracted from manager.ts to keep the class file under CLAUDE.md §3's 300-line hard cap. Both helpers (deriveCacheKey and checkAbortedSignal) are exercised through the manager's tests; they have no state and can be reused by any future internal collaborator that needs the same primitives.

Features

deriveCacheKey(url, verifyKey?) — stable cache key derivation that appends the first 8 bytes (hex) of the verify-key as a suffix so two loads against the same URL with different verify-keys live in separate cache slots.
checkAbortedSignal(signal, resolver, key?) — throw PackerBrowserError(ABORTED) when the supplied signal is already aborted; tolerates undefined for both signal and resolver so it works at every call site.

Usage: Basic Example

import { checkAbortedSignal, deriveCacheKey } from "./manager-helpers.js";

const key = deriveCacheKey("/asset.packed");
const keyed = deriveCacheKey("/asset.packed", new Uint8Array(64));
checkAbortedSignal(new AbortController().signal, undefined);

Usage: Advanced Example

import { checkAbortedSignal, deriveCacheKey } from "./manager-helpers.js";
import { defaultPackerBrowserResolver } from "../i18n/messages.js";

const ac = new AbortController();
ac.abort();
try {
    checkAbortedSignal(
        ac.signal,
        defaultPackerBrowserResolver,
        "packer-browser.error.ABORTED.preload"
    );
} catch (err) {
    console.error("preload aborted", err);
}

API Reference

deriveCacheKey(url: string, verifyKey?: Uint8Array): string.
checkAbortedSignal(signal: AbortSignal | undefined, resolver?: MessageResolver, key?: string): void.

Implementation Notes

The 8-byte cap on the verify-key prefix balances key uniqueness against cache-key memory cost. A full key would be 32 bytes hex- encoded (64 chars) per entry; the 8-byte prefix is enough to discriminate adversarially-distinct keys.
checkAbortedSignal accepts a custom message key so the same helper works for manager.load, manager.preload, manager.loadStream, and future async surfaces.
These helpers are NOT part of the public barrel — they're internal implementation details of the manager. Direct imports from outside the manager module are discouraged.

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