RxJS 9 beta.0 approval

Decision

The repository evidence approves rxjs@9.0.0-beta.0 and the synchronized four-package train to begin the RxJS 9 public beta under npm's next tag, once the configured blocking CI jobs are green. RxJS 7 remains npm's latest line and remains maintained.

This approval does not publish a package, create a GitHub release, promote RxJS 9 to latest, or approve the stable 9.0.0 release. Stable promotion requires public beta feedback and a separate explicit decision. The version number is 9 because the paused RxJS 8 effort predates this platform-based generation; RxJS 8 was not silently shipped or erased.

Adoption evidence

The exact four package artifacts were packed and audited locally. An isolated, offline consumer installed the rxjs, @rxjs/observable-polyfill, and @rxjs/test tarballs and passed:

• ESM imports and runtime behavior;
• Node 22.13, 24.12, and advisory 26.5 require(esm) behavior;
• strict public TypeScript declarations;
• @rxjs/test virtual-time behavior;
• a minified browser bundle using only the packed ESM files.

The browser bundle was 20,222 bytes. Packed artifact sizes were:

Package	Tarball bytes	Budget
rxjs	183,920	250,000
@rxjs/observable-polyfill	23,375	30,000
@rxjs/test	47,270	60,000
@rxjs/migrate	112,638	140,000

The audit found no source specs, CommonJS/browser/Webpack dialect copies, or missing package documentation. The Nx first-release version dry run resolves the complete train to 9.0.0-beta.0.

Broader qualification

• Focused product suites pass 51 polyfill, 750 RxJS, 75 test-harness, and 166 migration tests.
• Pinned Observable WPT passes all 52 URLs, 525 upstream subtests, and 52 exact implementation-identity attestations.
• Current Chromium, Firefox, and WebKit pass the shared eight-case lifecycle and Symbol contract. Desktop and Mobile Safari are separate blocking SafariDriver jobs; Mobile Safari requires an actual iOS simulator.
• Node, Deno, Bun, Webpack, bundle-size, and performance evidence passes the checked-in gates described in RELEASE_GATES.md.
• The representative migration program has three completed RxJS 7 migrations and one correct safe stop across Vitest, Mocha, Jest, application/library, cold, platform-shared, mixed, and unsupported contracts.

Known non-blockers

The complete source-pinned RxJS 7 corpus retains 39 cold and 22 fallback failures. Every one is a reviewed platform-lifecycle divergence or unsupported arbitrary-subscribable compatibility case. They are executable migration evidence, not hidden failures and not a promise of an RxJS 7 compatibility runtime.

Local branded Safari execution was not forced by changing a persistent host security setting. The clean-runner Safari and iOS simulator jobs are blocking conditions of publication, not waived evidence.

Publication boundary

The release process requires a clean, synchronized master checkout and one interactive pnpm release:beta 9.0.0-beta.0 command. It checks version identity, package-local documentation, ESM-only exports, package gates, and npm dry runs; prints the exact tarball integrities; and then uses npm's OTP/WebAuthn flow for each public package. The supporting packages publish first and rxjs publishes last. No CI credential or documentation application is part of publication.