Part C of the deferred unification cleanup. The Artists page is no
longer in the sidebar, but its JS file can't be deleted yet because
it houses ~20 general-purpose helpers that other modules depend on
(escapeHtml used in 229 places, service-status polling, image-colour
extraction, download-bubble infrastructure, discography completion
checking, enrichment card rendering).
Moved all non-page-specific code from artists.js into the new
webui/static/shared-helpers.js — pure copy/paste, zero logic change.
Two contiguous blocks extracted:
Block A (lines 1097..1398 of original artists.js): discography
completion suite — checkDiscographyCompletion, handleStreaming-
CompletionUpdate, cacheCompletionData, updateAlbumCompletion-
Overlay, getCompletionStatusText, setAlbumDownloadedStatus,
setAlbumDownloadingStatus.
Block B (lines 2206..EOF of original artists.js): download-bubble
infrastructure (artist + search + Beatport clusters with their
snapshot/hydrate/modal/monitor helpers), openDownloadMissingModal-
ForArtistAlbum, image-colour extractor and dynamic-glow helper,
escapeHtml, service-status polling, renderEnrichmentCards.
Function declarations in a plain <script> tag are auto-global, so all
existing callers continue to resolve without any import/export
changes. Load order in index.html: shared-helpers.js loads right
after core.js (which defines the artistDownloadBubbles / search-
DownloadBubbles / beatportDownloadBubbles globals these helpers use).
Stats:
artists.js: 4638 → 1903 lines (-2735)
shared-helpers.js: new, 2762 lines
No function duplicated between the two files
All 357 tests pass (3 new from split-integrity parametrization)
What's left in artists.js is purely the Artists page — search UI,
detail view, state switching, watchlist button, discography loading.
All of that is reachable only by typing /artists in the URL bar
since the sidebar entry was retired in Phase 4b. Parts D + E will
delete that remainder and the file itself.