[jongyoul]

What is this PR for?

Remove Helium Applications, Spells, external visualization packages, the registry/bundler, and related APIs, UI, RPCs, configuration, examples, and documentation in one change.

Preserve built-in tables/charts, ordinary interpreters, ResourcePool, and %angular. Keep legacy application metadata and chart settings when saving notes; unavailable external visualizations display as Table. Replacement visualizations are outside this change.

What type of PR is it?

Improvement

What is the Jira issue?

ZEPPELIN-6757

How should this be tested?

Rebased onto apache/master 5a74f537b; current head: 5087b8ce2.

Validated on the rebased head with Node.js 22.23.4:

• Angular shell tests: 319 passed.
• Modern frontend production build, including SDK, notebook-core, visualization, React remote, and Angular shell: passed.
• SDK contract typecheck and WebSocket contract checks: passed.
• Frontend lint completed with 0 errors and existing warnings; unrelated automatic E2E assertion rewrites were excluded. The conflict-resolved result-component spec passes ESLint and Prettier.
• Documentation navigation: reproduced the adjacent-divider issue on the previous head, checked the fixed separator structure and version-prefixed links, and inspected a source-derived preview at desktop and narrow widths.

Earlier implementation validation, before this rebase:

• JDK 11 server/upstream and shaded-interpreter builds; Classic frontend production build.
• 39 focused server tests, common message contract tests, and 135 interpreter tests.
• Visualization E2E (3 tests), server startup/API smoke checks, and Apache RAT.
• The full local server suite had 7 setup errors from missing Spark/Python runtimes. Building those prerequisites on this ARM Mac was blocked by the pinned x86_64 gRPC generator artifact. Classic WAR directory-access checks passed after packaging the WAR.

The full Jekyll documentation build remains unverified locally because Docker is unavailable. The source-derived navigation preview does not replace that build. GitHub CI must be checked on the rebased head; the previous head had failed npm-audit and Playwright E2E checks.

Questions

• License files: no update required.
• Breaking changes: Helium packages and their APIs are removed. Rebuild and restart the server and interpreter processes together because Application RPCs/events were removed.
• Documentation: Helium-specific pages and references are removed.

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[tbonelee]

Thanks for taking on this cleanup.

Could you rebase this PR onto master and remove the extra divider left in the docs site's More dropdown after removing the Helium section?

[jongyoul]

Thanks @tbonelee. Rebased onto master (5a74f537b) and removed the extra divider from the documentation site's More dropdown in 5087b8ce2.

The rebase preserves the newer HTML warning-dismissal behavior and its regression test alongside the built-in visualization tests. All 319 Angular shell tests pass, as do the frontend production build, result-component lint/format checks, SDK typecheck, and WebSocket contract checks.

I also checked the navigation in a source-derived preview at desktop and narrow widths. Docker is unavailable locally, so I could not run the full Jekyll documentation build. The PR description now separates current checks from the earlier implementation validation.

[tbonelee]

Thanks for the update. The rebase and divider fix look good.

With SystemJS removed, Monaco no longer exposes its global API, but the editor and theme code still rely on it. This throws during edit handling and prevents changes from being saved.

I tried replacing those global references with explicit imports in e4739faea. All 320 shell tests and focused browser checks for saving, reloading, collaboration, theme switching, and table pagination passed locally.

Could you update the remaining references along these lines?