[mixelpixx]

Summary

The name, icon and title already set Arduino Agent apart, but inside it still used Arduino's teal everywhere. This PR moves both built-in themes to the indigo of the app icon.

How the colors are derived (agent-palette.ts, pure OKLCH math): instead of hand-picking a palette, Arduino's own theme JSON is transformed when the themes are registered.

• Accents: teal (hue 160–240, chroma ≥ 0.05) moves to the icon's hue, 277°, at the same lightness, with a little more chroma. For example #008184 → #5d64c6, #0ca1a6 → #757ff4, and the status bar #006d70 → #4e54a8.
• Neutrals: Arduino's slightly teal-tinted slates keep their lightness and their tiny chroma, but lean indigo instead. For example the dark editor background #1f272a → #24252c.
• Everything else: whites, greys and the yellow/red highlights are untouched. Keeping lightness preserves the contrast Arduino tuned.

Wiring (agent-theme.ts)

• Theme IDs kept: the converted themes are registered under Arduino's IDs (arduino-theme, arduino-theme-dark). The vendored settings dialog lists exactly those as the built-in Light/Dark, and users' saved workbench.colorTheme keeps working. Since the conversion runs on Arduino's JSON at registration, upstream theme updates carry over.
• Upstream bug fixed: arduino.branding.primary/secondary are now registered. Arduino's themes set them, and its CSS uses var(--theia-arduino-branding-primary) in the boards dialog, the library and board lists, the serial monitor scrollbar and the progress bar. But upstream never registers them, so the variable was undefined in every build and those accents never rendered.
• Hardcoded CSS overrides: the few rules in arduino-ide-extension's CSS that hardcode teal are overridden in terms of the branding color: the board/port status-bar items, the dialog border, list separators and the focus shadow.

Test plan

• yarn test:palette (new) passes 4/4:
  • teal accents land on hue 277 at the same lightness
  • neutrals stay below chroma 0.03
  • non-teal colors and alpha suffixes are untouched
  • both Arduino themes convert with no teal accents left, and the input is not mutated
• A swatch page of every before→after mapping in both themes, reviewed.
• A local Windows build, with screenshots of both themes. The light theme was forced by emulating prefers-color-scheme and reloading, so nothing was persisted.
  • Light: indigo toolbar and status bar, periwinkle Verify/Upload buttons, indigo keywords.
  • Dark: neutral charcoal backgrounds with no purple cast, indigo buttons and keywords, and the board status item tinted.
• --theia-arduino-branding-primary is now defined (#5d64c6 light, #757ff4 dark). It was empty before.
• CI.

🤖 Generated with Claude Code