[Bug]: provider badge initials are invisible on light accent colors

[Mnigos]

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/web

Steps to reproduce

1. Open Settings → Providers and edit a provider instance (for example Codex).
2. Set a custom accent color to white #ffffff (any light color reproduces it).
3. Look at the provider icon in the sidebar, the model picker, or Settings → Usage.

Expected behavior

The account badge keeps its initials readable for every accent color. A light accent should get dark text, a dark accent should get light text.

Actual behavior

The badge always paints its initials in white (text-white in apps/web/src/components/chat/ProviderInstanceIcon.tsx), so with a white or light accent the initials disappear. In the screenshot below Codex has a white accent and shows no "CO", while Claude's orange accent still shows "CL".

The mobile badge has the same hardcoded white text in apps/mobile/src/components/ProviderIcon.tsx.

Impact

Cosmetic issue

Version or commit

0.0.40-nightly

Environment

macOS desktop app, dark theme

Screenshots, recordings, or supporting files

See the screenshot above.

[juliusmarminge]

Thanks for the clear repro and screenshot — this checks out.

The account badge always paints initials in white:

• web: text-white on the accent chip in apps/web/src/components/chat/ProviderInstanceIcon.tsx (sidebar, model picker, Settings → Usage)
• mobile: color: "#ffffff" in apps/mobile/src/components/ProviderIcon.tsx

So any light accent (#ffffff, pastels) hides the letters. Desktop uses the web component, so both clients need the same contrast rule.

This is not a duplicate of #11562 / #11610 (badge overlapping the logo). #7968 only fixed the neutral badge background for dark themes and left accent text white.

Suggested fix: pick black vs white from the accent’s relative luminance (theme code already does this in readableThemeForeground / apps/web/src/themePalette.ts). Put the helper next to normalizeProviderAccentColor in packages/client-runtime so web and mobile stay aligned. A threshold a bit above the WCAG midpoint keeps existing mid-tone accents (e.g. Claude orange) on white text.

#11643 already implements that (Fixes #11641). Review that PR rather than starting a second fix.

Cosmetic / a11y-adjacent bug; accepted as a small UI fix.