[teamleaderleo]

This PR is the primitive, the Debug toggle and the host feed. Adoption on the surfaces (composer, bubbles, queue card, menus and popovers, hover/link/Updated cards, jump pill) follows right after in its own PR; the gallery entry ui.liquid-glass shows them all.

Liquid glass with a real lens: the wallpaper bends at each glass rim, with a thin specular rim and an optional chromatic fringe (Spectrum). One shared web primitive, .ui-glass.

The lens is off by default. Leo (2026-10-21): "the lens thing we just need to see and feel... we can put it as a toggle and later promote to default". Today's glass (Plain Glass) is unchanged for everyone. In DEV and NIGHTLY builds, the Debug Settings choice glass.lens (Glass and Overlays > Liquid Glass: Plain Glass, Lens, Spectrum) turns it on, and Toggle Liquid Glass Lens in the command palette or the Debug menu flips Plain and Lens live. It lives in the build's debug-tunables.json, outside the settings schema, so there is no Settings row and no new default; Release never activates Debug Settings and stays Plain. A Settings > Appearance control comes back when the lens is promoted.

Design: plans/cmux-next/glass-lens-DESIGN.md. WebKit can't refract a backdrop (backdrop-filter: url() parses but renders nothing; probed on macOS 27), and the wallpaper is drawn natively behind transparent web views. So the host sends each page a still of the wallpaper and its rect (cmuxTheme.backdrop), and one WebGL canvas per page lenses that copy under every visible .ui-glass.

• Web (webviews/src/ui/glass/): tokens --glass-tint, --glass-blur, --glass-frost, --glass-refraction, --glass-rim, --glass-dispersion; class .ui-glass; the lens (lens.ts), which does nothing in Plain, under Reduce Transparency, with no still, or with no glass on screen, and whose rAF loop runs only after scroll, resize, DOM or animation changes. Gallery entry ui.liquid-glass over a generated wallpaper.
• Host: the Debug choice glass.lens (GlassLensMode.tunable); effective mode is Plain under Reduce Transparency or Low Power Mode, sent as data-glass. GlassBackdropFeed per web view (PageWebView, AgentPaneView, AgentActivityHostView) sends the art as drawn (JPEG, ≤1024 px, off the main thread, cached), its aspect-filled rect, blur and tint; null for video, no art or translucent art.

Media

The PR head built on a fleet mini (cmux-austin-mini-0), the gallery's glass transcript in a cmux NEXT browser tab over a colorful wallpaper:

Lens	Plain Glass	Spectrum

Video, scrolling under the lens (stepped captures, not real time): lens-scroll-stepped.mp4

Frame time

Same mini (M4, 60 Hz display, no 120 Hz mini in the fleet), PR head app build, 400 turns (402 glass surfaces, 9 on screen), constant 1800 px/s scroll, 6 runs x 6 s per mode:

Mode	p50	p95	p99	dropped
Lens	17 ms	18 ms	19 ms	0.14%
Plain	17 ms	17 ms	19 ms	0.09%
Spectrum	17 ms	18 ms	19 ms	0.23%

60.0 fps in every mode; drops are mostly each run's first frame. This counts requestAnimationFrame cadence, not compositor-side misses, at 1x scale.

Changelog

Added: An opt-in Liquid Glass lens for glass surfaces in DEV and NIGHTLY builds (Toggle Liquid Glass Lens in the palette or the Debug menu); the default glass is unchanged.

Observed / Not run

Observed:

• bun test test/glass-state.test.ts: 13 pass. CMUX_BROWSER_TESTS=1 bun test test/glass-lens.test.ts: 10 pass in Chromium and WebKit (stripes displaced at the rim, not at the center or outside; no canvas in Plain or under Reduce Transparency; one redraw per move, then the loop stops; canvas removed with the last glass).
• Gallery captures over the fixture wallpaper in all modes, both engines: the rim bends and magnifies the wallpaper; text under the composer and a menu frosts.
• Scrolling 120 glass bubbles one step per frame, headless WebKit: p50 17 ms, p95 21 ms (plain: p50 17 ms). On a fleet mini in the app: see Frame time.
• Two independent review passes (heads a885dbe, 55af381).
• Fleet at the merged head 6acb984 (the final head 048ea3c only adds the regenerated action exports on top): cmux-ci compile-check --app passed; GlassLensTests, GlassBackdropTests, PaletteRankCatalogTests, ActionContractTests, ActionSurfaceParityTests, PaletteMenuVocabularyTests pass (aws-m4pro-7).
• Settings exports regenerated on the fleet at that head are byte-identical to base; defaults_guard.py check-stamp passes (no new default).
• Gallery accent/glass invariant scan of the Inspector, Summary card, Updated (changelog update surfaces) and Chief inspector entries: 32 stages, 0 opaque-glass findings.
• bun run check: one type error in test/editor-find-narrow.test.tsx, unchanged here and red on base (from fix(cmux-next editor): the find pill stays inside a narrow editor #22872).
• Webview shard reds: each failing file compared head vs base locally; the same counts fail on base (chief-context-copy, composer-history, composer-location-strip, composer-mention, composer-suggested-prompt, quiet-access-chip, settings summaries over 60 chars), the rest pass on both.
• prepush-gate.py: no new violations.

Not run:

• The native wallpaper feed in the app (the mini run used the gallery's fixture still), a Retina 2x display and 120 Hz.
• Flipping the toggle in a running NIGHTLY build (covered by GlassLensTests through the tunable store and by the compile; not clicked by hand).

Leo-ask: ask-0e7ea215d7
Leo-ask: ask-b5bfc7b208

Agent session: cmux16

🤖 Generated with Claude Code

[github-actions]

cmux status _{(one comment, edited in place; each line is updated by the job that owns it)}

Review 048ea3c: HQ feed card · gallery before/after runs · checks

App of this head (app.zip, kept 1 day)

gh workflow run reload-build.yml -R manaflow-ai/cmux --ref feat-cmux-next -f tag=pr22815 -f ref=cmux/glass-lens -f platform=macos -f backend_mode=local

Gallery before/after for 048ea3c: 16 states rendered, 16 images differ, 1484 more touched states not rendered. Images are in the run's artifact, not on this public PR.

gh run download 39679527628 -R manaflow-ai/cmux -n gallery-advisory-22815-048ea3cc4d8db36cfca894cfeb5e4ea549a76ebd (then read gallery-review.json)

States

State	Theme	Status	Diff	Picked by
pages.agent-activity/empty	Apple System Colors Light	unchanged	0%	own desktop.css
pages.agent-activity/empty	Apple System Colors	unchanged	0%	own desktop.css
pages.agent-activity/split	Apple System Colors Light	unchanged	0%	own desktop.css
pages.agent-activity/split	Apple System Colors	unchanged	0%	own desktop.css
pages.agent-activity/timeline	Apple System Colors Light	unchanged	0%	own desktop.css
pages.agent-activity/timeline	Apple System Colors	unchanged	0%	own desktop.css
pages.agent-activity/grid	Apple System Colors Light	unchanged	0%	own desktop.css
pages.agent-activity/grid	Apple System Colors	unchanged	0%	own desktop.css
ui.liquid-glass/lens	Apple System Colors Light	new	0%	own Glass.tsx
ui.liquid-glass/lens	Apple System Colors	new	0%	own Glass.tsx
ui.liquid-glass/plain	Apple System Colors Light	new	0%	own Glass.tsx
ui.liquid-glass/plain	Apple System Colors	new	0%	own Glass.tsx
ui.liquid-glass/spectrum	Apple System Colors Light	new	0%	own Glass.tsx
ui.liquid-glass/spectrum	Apple System Colors	new	0%	own Glass.tsx
ui.liquid-glass/lens-light	Apple System Colors Light	new	0%	own Glass.tsx
ui.liquid-glass/lens-light	Apple System Colors	new	0%	own Glass.tsx
ui.liquid-glass/plain-light	Apple System Colors Light	new	0%	own Glass.tsx
ui.liquid-glass/plain-light	Apple System Colors	new	0%	own Glass.tsx
ui.liquid-glass/spectrum-light	Apple System Colors Light	new	0%	own Glass.tsx
ui.liquid-glass/spectrum-light	Apple System Colors	new	0%	own Glass.tsx
ui.liquid-glass/lens-text	Apple System Colors Light	new	0%	own Glass.tsx
ui.liquid-glass/lens-text	Apple System Colors	new	0%	own Glass.tsx
ui.liquid-glass/plain-text	Apple System Colors Light	new	0%	own Glass.tsx
ui.liquid-glass/plain-text	Apple System Colors	new	0%	own Glass.tsx
agent-pane.composer/new-chat	Apple System Colors Light	unchanged	0%	names README.md
agent-pane.composer/new-chat	Apple System Colors	unchanged	0%	names README.md
agent-pane.composer/side-session	Apple System Colors Light	unchanged	0%	names README.md
agent-pane.composer/side-session	Apple System Colors	unchanged	0%	names README.md
agent-pane.composer/new-chat-suggest-open	Apple System Colors Light	unchanged	0%	names README.md
agent-pane.composer/new-chat-suggest-open	Apple System Colors	unchanged	0%	names README.md
agent-pane.composer/new-chat-suggest-failing	Apple System Colors Light	unchanged	0%	names README.md
agent-pane.composer/new-chat-suggest-failing	Apple System Colors	unchanged	0%	names README.md

_{Pick other states with a Gallery: entry.id, entry.id/variant line in the PR body.}

Not verified: macOS jobs did not run: compile and app tests were skipped on 048ea3cc4d; ci-status is green without them.

CI passes on 048ea3cc4d (run 39679876143 attempt 1).
macOS jobs did not run: compile and app tests were skipped: Fast static checks skipped (the macos job needs both to succeed). Re-run CI once they pass, before merging.

Written by scripts/ci/classify_failures.py (ci-failure-attribution.yml); signatures are its SIGNATURES table. A machine verdict is the runner's fault, not this PR's; yours means the failing file is one this PR changes, also red on main that main's latest full suite fails the same way, seen on other PRs that it failed on another pull request's run lately.

web and size checks: green

CI fast guards passes on 048ea3cc4d (run). This covers only the fast guards, not CI: CI's result is ci-status.

Tour of 048ea3cc4d (run): no media. The tour job failed before the tour ran (build or setup); the run log has the output.

[teamleaderleo]

Bead cx-eydu9 created for this PR by the cmux coordinator.

[teamleaderleo]

owner: 01a15c40-f076-7583-9fcd-099f2a1deab4

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[blacksmith-sh]

Found 6 test failures on Blacksmith runners:

Failures

Test	View Logs
/tmp/tmpazmrxgtj/summary-missing.json (live):/summary-missing.json (live):	View Logs
/tmp/tmpke6b9sml/summary-fail.json (live):/summary-fail.json (live):	View Logs
[new_workspaces] debug.new_workspace timed 0 of 50 new workspace rows/ [new_workspaces] debug.new_workspace timed 0 of 50 new workspace rows	View Logs
[new_workspaces] the window draws no frames/[new_workspaces] the window draws no frames	View Logs
[tabs] debug.tab_switch timed 0 of 40 switches/ [tabs] debug.tab_switch timed 0 of 40 switches	View Logs
[tabs] the window draws no frames/[tabs] the window draws no frames	View Logs

^{Need help on this PR? Tag @codesmith-bot with what you need.}

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[teamleaderleo]

cmux-next crash-class rules / cmux-next crash-class rules is red on 14 of 15 fresh feat-cmux-next PR heads in the last 2:00:00, so it is most likely a base red, not this PR's. The base-reds lane has it; a base merge picks up the fix once it lands.

[teamleaderleo]

Review (independent review subagent): SHIP at 800de14

Delta since the reviewed 6126d33: a base merge of feat-cmux-next (89078c9, which brings in #23478) and the settings exports regenerated on the fleet (800de14, cmux-ci step 488cb6a08483a6ed97777436).

• PR lines unchanged: for all 38 PR files, the added and removed lines are identical before and after the merge (AgentPaneView, PageWebView, WebTheme, AppServices, AppDelegate, desktop.ts, lens.ts among them).
• Strings: Localizable.xcstrings is valid, and each of the 5 glass keys appears once.
• Generated files: check-stamp passes, and the schema and MDM diff adds only the Glass setting.
• Base and glass: base adds no new .ui-glass or --glass-* uses that this PR would double-apply.

Evidence at this head:

• Fleet compile-check --app passed (job d3385607dcf3e70a4f828018, 74 s).
• SidebarPinnedRowWidthTests passes (step 5fc52a01ede4f27a676108bd, aws-m4pro-7). It was red at the old base e6fb991 and is fixed by cmux-next sidebar: pinned rows end where the other rows do (row trim) #23478.
• At the merge commit 89078c9, HiddenPageHibernationTests and SidebarIncrementalMatchesRebuildTests pass on the same worker (step acaa83998697d89929e38fd6).
• bun run check is clean, and the glass and desktop tests pass.

The defaults call is still needed: the new appearance.glass default ("lens") needs an approving review on this head from a call owner.

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[teamleaderleo]

Review (subagent): SHIP at 048ea3c

Correctness review of the final head. Default unchanged: with no Debug override every page draws Plain glass. The settings schema, docs/mdm and the sources sha256 match base, and defaults_guard passes. The Debug toggle glass.lens is registered and live: GlassModeWatch triggers ThemeStore.repaintAll, then data-glass. The action is debug-only, offered in the palette and the Debug menu, and hidden in Release. No GlassSetting or appearance.glass leftovers. Exports match the catalog. The lens stays inert in Plain: no canvas, no WebGL, no feed. Never-opaque check clean; glass-state and glass-lens tests pass. Fleet at merged head 6acb984: app compile passed; GlassLensTests, GlassBackdropTests, PaletteRankCatalogTests, ActionContractTests, ActionSurfaceParityTests, PaletteMenuVocabularyTests pass.

[teamleaderleo]

CI at 048ea3c: 61 passed, 1 red: gallery health agent-pane.url-chip#pull-request-lines-by-kind: play: waitFor did not hold. That is a base red: the same state fails on feat-cmux-next run 39679793310 and on unrelated PRs (composer-look-plain-glyphs, composer-look-model-button, next-project-framework-icons, chat/live-line-rhythm). Fleet cmux-ci compile-check --app at 048ea3c: passed (job 5bff6acbf2b0691edbe8eb3e).

[github-actions]

Shipped in:

• cmux NEXT nightly 1.0.0-nightly.3969193688601 (ae0085bef4)
• cmux NEXT nightly 1.0.0-nightly.3969270034001 (ceb44fc207)
• cmux NEXT nightly 1.0.0-nightly.3969340227301 (01b25c3563)
• cmux NEXT nightly 1.0.0-nightly.3969476605401 (28c01c3aaa)
• cmux NEXT nightly 1.0.0-nightly.3969569695701 (3955ea8e00)