Root cause: every local resource preview tab kept its own /api/local-folder/events EventSource alive. Hidden PDF and Office tabs consumed browser same-origin connection slots, so later preview iframes/file reads stalled and rendered as blank pages.
Changes:
- keep passive resource file watching active-tab only
- close inactive resource-tab EventSources on tab activation and release
- update the bug record with the PDF fifth-open and XLSX fourth-open repro and verification
Verification:
- node --check rust/crates/mnote-web/browser/document-resource-tab-runtime.js
- cargo test -p mnote-web --manifest-path rust/Cargo.toml pdf_preview_page_does_not_render_visible_toolbar
- cargo test -p mnote-web --manifest-path rust/Cargo.toml document_shell_returns_page_aggregate_snapshot
- cargo build -p mnote-web --manifest-path rust/Cargo.toml
- browser smoke: opened 5 XLSX previews; #4 and #5 completed with tableCount=1
- browser smoke: opened 5 DHA PDFs; #5 rendered 8/8 canvases, iframeCount=0, browser errors=0
lix-2026
eccf399142