fix(chat): restore the mars rover backdrop in inbox search

[chrisnojima]

The parallax mars scene at the bottom of the desktop inbox search pane was gone. Two independent bugs, either of which alone was enough to hide it.

Zero-area lazy images never load

ImageIconDesktop emits an <img> with no width/height attribute. The scene's three layers are absolutely positioned with only bottom/left, so each had a 0×0 layout box until its bitmap arrived — and Chromium never fires lazy-load for a zero-area box, so the image that would have given it a size could never load. Silent: complete:false, naturalWidth:0, no network request, no console error.

Confirmed with a cache-busted A/B matrix in the running app:

position	loading	size	result
absolute	lazy	unsized	never loads
absolute	lazy	sized	loads
absolute	eager	unsized	loads
static	lazy	unsized	never loads

So it's the zero area, not position: absolute. The rover sprite escaped only by luck of its in-flow wrapper.

Fix: give each layer the asset's own pixel size. The wrapper styles are split from the image styles so the names mean what they say, which also drops roverLayer — its bottom/left were dead, overwritten inline by transRoverY/transRoverX every render.

srcSet advertised candidates with no file behind them

srcSet was hardcoded to 1x, 2x, 3x for every icon, but 22 icons in iconMeta don't ship all three — the mars trio has no @3x. The browser picks one candidate up front and never falls back if it 404s, so at devicePixelRatio 3 (Windows at 300% scaling) all three 404'd and the scene stayed missing even once sized. Worse, a sized failed image draws a broken-image glyph where an unsized one drew nothing, so fixing the first bug alone would have traded "invisible" for "three broken glyphs".

The generator already read the full directory listing and threw the @2x/@3x information away. It now records the available multiples as mults, emitted only when it isn't the default [1, 2, 3], and image-icon builds srcSet from that — so a missing @3x falls back to @2x. The dark <source> now resolves its directory and extension from the dark asset's own name rather than the light icon's (latent, but an all-404 dark srcSet for any asset that differed).

Also

icon-placeholder-avatar-lighter-32@2.png and @3.png are really 64px and 96px retina art that lost the trailing x in their filenames, so the generator read them as separate 1x icons and was about to bake mults: [1] into the constants, pinning that icon to the 32px asset forever. Renamed.

Verification

In the running app against a cold cache (the probes warm these URLs, so a warm run is a false green), reloaded under the DPR override — setDeviceMetricsOverride alone does not re-run srcset selection on already-loaded images:

• DPR 3: picks @2x, loads, renders 539×379 / 74×78 / 539×90. Previously 404 on all three.
• DPR 2: same.
• Zero 4xx image responses app-wide on both runs; previously three.
• A dark-variant icon's <source> still resolves all three candidates against the dark asset name.

yarn lint:all clean — eslint quiet, 1727 compiled / 0 bailed out / 0 whole-props deps, tsc green on both desktop and native.

[Copilot]

🟡 Changes recommended

The generator-updated icon.constants-gen.d.ts declarations don’t currently include the new multsFor export, which can break typed consumers relying on that .d.ts.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Restores the desktop inbox-search Mars rover parallax backdrop by (1) preventing srcSet from advertising non-existent density candidates and (2) ensuring the parallax layers have non-zero layout size so Chromium lazy-loading will actually fetch them.

Changes:

• Generate and consume per-asset available retina multipliers (mults) so desktop srcSet only includes files that exist (including correct resolution for dark variants).
• Adjust inbox-search rover backdrop layout so each layer has explicit pixel dimensions and uses a dedicated positioning wrapper.
• Rename/add corrected retina placeholder-avatar assets so the generator doesn’t misclassify them as separate 1x icons.

File summaries

File	Description
shared/desktop/yarn-helper/font.mts	Generator now detects which @Nx variants exist per asset and emits mults metadata.
shared/common-adapters/icon.constants-gen.tsx	Adds multsFor() helper to expose per-icon multipliers with a default fallback.
shared/common-adapters/icon.constants-gen.shared.tsx	Generated metadata now includes mults for assets missing some multipliers (e.g. Mars rover layers).
shared/common-adapters/icon.constants-gen.d.ts	Updates generated declaration types for mults/nameDark (but currently missing a multsFor export declaration).
shared/common-adapters/image-icon.tsx	Desktop srcSet now built from multsFor() and resolves dark <source> candidates using the dark asset’s own dir/extension.
shared/chat/inbox-search/background.tsx	Adds explicit sizing and wrapper styles so lazy-loaded absolutely-positioned layers are fetchable/rendered.
shared/images/icons/icon-placeholder-avatar-lighter-32@2x.png	Updated/renamed asset to correctly represent a 2x retina candidate.
shared/images/icons/icon-placeholder-avatar-lighter-32@3x.png	Updated/renamed asset to correctly represent a 3x retina candidate.

Review details

• Files reviewed: 5/8 changed files
• Comments generated: 1
• Review effort level: Lite

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