emrg: GUI workspace panel P2.3+P3.4 — WebContentsView HTML preview (rant 2026-08-11T12:20:35)

[argszero]

GUI right-column workspace panel: final major slice — embedded-browser HTML preview via WebContentsView (last remaining item of the rant's P2.3 framework + P3.4 preview content, which the design allows to land together).

P2.3 WebContentsView framework (main.js)

• Lazy creation on first HTML tab (R7-⑤): new WebContentsView({ sandbox: true, contextIsolation: true, nodeIntegration: false }), single instance reused (one preview at a time)
• Bounds sync (R4-②): right-aligned rect {x: winW-panelW, y: contentTop, w: panelW, h: winH-contentTop}; contentTop = viewer pane top reported by renderer; updated on win resize + emrg:panelResized IPC (width / collapse / narrow-screen)
• Security checklist (gap 8): setWindowOpenHandler → deny; will-frame-navigate → main-frame navigations restricted to file: (remote URLs blocked)
• Collapse → view hidden (bounds to offscreen, setVisible false)
• Renderer crash recovery (R5-④): main keeps preview path as source of truth; renderer pulls via emrg:getPreviewState after reload and reopens the tab

P3.4 HTML preview (renderer)

• .html/.htm → embedded preview (no read_file call); DOM placeholder (mixed model) visible when collapsed
• Tab switch semantics: HTML→HTML = reload (loadURL replace), HTML→non-HTML = closePreview, close tab = closePreview
• i18n zh/en result.htmlPreview; CSS .viewer-html placeholder

Verification: GUI 212/212 (+7 renderer smoke tests: IPC calls, html-path detection both states, html→html reload semantics, close/switch closePreview, panelResized reporting on init/collapse/expand, crash-recovery reopen, idempotent reopen), pytest 694/694, doc-count guard 3/3, import + --help ✓.

Rant 2026-08-11T12:20:35 acceptance: P1-P3 all slices now merged/submitted (P3.3 viewer #670 merged; this PR closes the last item).

[argszero]

✅ LGTM — cycle

P2.3+P3.4 WebContentsView HTML preview — final major workspace-panel slice. Verified locally:

• main.js: lazy WebContentsView (sandbox+contextIsolation+nodeIntegration:false), right-aligned bounds via previewRect (win resize + emrg:panelResized), will-frame-navigate file:-only main-frame gate + setWindowOpenHandler deny, preview path held in main as crash-recovery source of truth
• renderer: .html/.htm → embedded preview (no read_file), DOM placeholder mixed model, HTML→HTML reload / HTML→non-HTML closePreview semantics, panelResized on init/width/collapse, getPreviewState reopen after renderer crash
• GUI 212/212 (+7 renderer smoke), pytest 694/694, doc guard 3/3, import + --help ✓
  CI test PASS (31464133515).

[argszero]

✅ LGTM — cycle

Verified in worktree (head 7036193): GUI 212/212 (+7 renderer smoke: previewHtml IPC, html-path detection both states (.html/.htm/.HTM → preview; .py → readFile), html→html reload semantics, close/switch closePreview, panelResized init+collapse/expand, crash-recovery reopen, idempotent handlePreviewState), pytest 694/694, doc-count guard 3/3, node --check clean, CI test SUCCESS, MERGEABLE.

Security checklist confirmed: WebContentsView sandbox+contextIsolation+nodeIntegration:false (mirrors main window), setWindowOpenHandler deny, will-frame-navigate restricts main-frame to file: URLs, lazy create/single instance reuse, collapse → offscreen bounds, renderer-crash recovery with main as source of truth (emrg:getPreviewState). Closes the final rant slice (P2.3+P3.4) after #670.

[argszero]

✅ LGTM — cycle

Third LGTM. Verified at head 7036193 (merge base = master 80ab4a0, MERGEABLE):

• main.js: WebContentsView lazy creation (sandbox + contextIsolation + nodeIntegration:false), right-aligned previewRect bounds synced via emrg:panelResized + win resize, will-frame-navigate file:-only main-frame gate + setWindowOpenHandler deny, crash-recovery source of truth via emrg:getPreviewState
• renderer: .html/.htm embedded preview (no read_file) with DOM placeholder, syncPreview (HTML→HTML reload / non-HTML closePreview), panelResized reporting, idempotent handlePreviewState
• Tests: GUI 212/212 (+7 renderer smoke), pytest 694/694, doc guard 3/3
  CI test PASS (31464133515). Mergeable CLEAN.