[ZEPPELIN-5235] Add Cancel all paragraphs button to the new UI

[HwangRock]

What is this PR for?

The note action bar has a run-all button but no way to stop a note from the UI. Stopping a running
note is only reachable through DELETE /api/notebook/job/{noteId}, so a user who starts a long note has
to leave the page and issue a REST call, or cancel each paragraph one by one.

This adds a Cancel all paragraphs button next to run-all in the new UI. The button sends a new
CANCEL_ALL_PARAGRAPHS websocket message, and cancelAllParagraphs() in NotebookService aborts
every paragraph of the note that has not terminated yet.

The abort loop already existed inline in stopNoteJobs() in NotebookRestApi. It is extracted to
Note.abortAll() so the REST endpoint and the websocket handler share one implementation instead of
drifting apart. Permission handling follows the existing run path: the service checks
Permission.RUNNER the same way cancelParagraph() does, and the note is reached through
notebook.processNote() so the note lock is held while paragraphs are aborted.

No new cancellation mechanism is introduced. Note.abortAll() calls the existing Paragraph.abort(),
which delegates to interpreter.cancel() exactly as single-paragraph cancel does today. The button is
disabled in revision view and while no paragraph is running.

What type of PR is it?

Improvement

Todos

• - Extract Note.abortAll() and reuse it from stopNoteJobs()
• - Add CANCEL_ALL_PARAGRAPHS op and NotebookService.cancelAllParagraphs()
• - Add the button to the new UI action bar and the message to the SDK
• - Unit tests for the notebook, service and socket layers

What is the Jira issue?

https://issues.apache.org/jira/browse/ZEPPELIN-5235

How should this be tested?

NotebookServiceTest covers the success path, the forbidden path for a non-runner, and an unknown
note id. NotebookServerTest covers the op routing. NotebookTest covers Note.abortAll() leaving
terminated paragraphs alone.

Manually: create a note with six python paragraphs where the first two finish within a few seconds and
the rest sleep for minutes, run all, then press the button while a paragraph is running. The running
paragraph moves to ABORT, the finished ones keep FINISHED, and paragraphs that never started stay
untouched.

Screenshots (if appropriate)

2026-08-15.7.51.13.mov

Questions:

• Does the license files need to update? No.
• Is there breaking changes for older versions? No. The REST behaviour is unchanged and the new op is additive.
• Does this needs documentation? No.

[jongyoul]

LGTM for the backend part.

[voidmatcha]

LGTM 👍

One thing in the description: it says stopping a note is reachable through PUT /api/notebook/job/{noteId}, but the endpoint is @DELETE (NotebookRestApi.java:879). There is no PUT on that path.

[HwangRock]

Good catch, stopNoteJobs() is @DELETE, not PUT. Fixed the description. Thanks @voidmatcha!

[voidmatcha]

Merged into master (2cc438b).