Add sync module

[streamich]

Introduces very light-weight Signal-like reactive primitives that work well with React.js external sync store.

import {val, comp} from 'thingies';

const view = val<'display' | 'edit'>('display');
const formatting = comp([view], (view) => {
  if (view !== 'edit') return;
  return new Formatting(123);
});

[Copilot]

Pull request overview

Adds a new sync module providing lightweight synchronous reactive primitives (Value, Computed) intended to integrate with React’s useSyncExternalStore, along with tests and documentation, and updates the Jest toolchain.

Changes:

• Introduces src/sync.ts with Value, Computed, and val/comp helpers.
• Exposes the new module via src/index.ts and documents it in README.md.
• Adds comprehensive Jest tests for the new primitives and upgrades Jest/@types/jest dependencies (with corresponding lockfile updates).

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
yarn.lock	Updates dependency lockfile due to Jest/tooling upgrades.
src/sync.ts	Adds reactive sync primitives and React external-store-compatible interfaces.
src/index.ts	Re-exports the new sync module from the package entrypoint.
src/tests/sync.spec.ts	Adds test coverage for Value/Computed behavior, caching, and disposal.
package.json	Upgrades Jest + typings (toolchain impact).
README.md	Documents the new Value/Computed primitives and factories.

Comments suppressed due to low confidence (1)

package.json:54

• Jest was bumped to v30 but ts-jest is still on the v29 line, while the test runner is configured to transform TS via ts-jest (jest.config.js). In yarn.lock, ts-jest@29.3.0 pulls jest-util@^29.0.0, which is a strong indicator it targets Jest 29 APIs. Please align versions (upgrade ts-jest to a Jest-30-compatible release, or keep Jest on v29) to avoid runtime/transform incompatibilities in CI.

    "@types/jest": "^30.0.0",
    "benchmark": "^2.1.4",
    "husky": "^8.0.0",
    "jest": "^30.3.0",
    "prettier": "^3.0.0",
    "pretty-quick": "^3.1.1",
    "rimraf": "^3.0.2",
    "ts-jest": "^29.1.2",
    "tslib": "^2.6.2",

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[Copilot]

There is trailing whitespace after the closing brace; this can cause unnecessary diffs and may fail stricter linters/formatters. Please remove the trailing space.

[Copilot]

The public API currently passes dependency snapshots as a single array/tuple argument (compute(args: V)), but the PR description example uses a single-value callback (comp([view], (view) => ...)). As implemented, that example would receive [view] (an array) rather than view. Either update the API to call compute(...snapshots) (and type it as (...args: V) => N) or update the docs/examples to reflect the tuple-argument shape (([view]) => ...).

[github-actions]

🎉 This PR is included in version 2.6.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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