ui: unified theme selector with seasonal scene packs (C3X + C4)

[ghbarker]

What this adds

A single Theme selector (Settings → Visuals) on both the comma 3X and comma four UIs, driven by one BPThemePack param and one shared entry list — so theming is selected the same way on both devices. The selector carries:

• Off (stock UI)
• 8-Bit Racer — the existing theme, absorbed into the selector (its separate toggle is removed)
• Ten seasonal packs: New Year's, Valentine's, St. Patrick's, April Fools, Easter, Cinco de Mayo, Fourth of July, Halloween, Thanksgiving, Christmas

Theme packs are asset-only

<pack_name>/
  colors/colors.json        # Path, PathEdge, LaneLines, LeadMarker, RoadEdges, Accent, Background — all optional
  sounds/<name>.wav         # optional alert-sound overrides by filename (mono 16-bit 48 kHz)
  steering_wheel/wheel.png  # optional wheel icon

New themes need zero code. Users can also drop packs into /data/bp_themes/ over SSH — discovered automatically, same-name user packs shadow bundled ones. Everything degrades gracefully: a malformed wav falls back to the stock sound, a missing color key keeps the stock color.

Themed views render as full scenes

v2 — animated + static scene layers. Each pack may ship a scene.json consumed by one
shared scene engine (theme_scene.py): particle layers (falling snow, rising hearts,
tumbling leaves, fluttering bats, firework bursts), static decor (string lights with
catenary droop, berry garlands, flag bunting, a carved pumpkin) and a sky treatment —
full strength in Minimal Driving View, subtle over the live camera, alerts always on
top. Sprites are procedurally rendered signed-distance fields, so the PR contains no
new image assets: every snowflake, heart and bat below is generated from math at load
time and tinted per particle. The scene architecture is one modular interface
(SceneBase with background/foreground passes + capability flags); 8-Bit Racer now
rides the same dispatch through a capability adapter with its drawing untouched, and a
pack without scene.json renders exactly as before. Budgets are hard-capped and
validated — a malformed user scene.json degrades to colors-only. 24 new tests.

• Background paints a sky gradient behind the road whenever Minimal Driving View hides the camera
• The path ribbon runs a full-strength gradient (PathEdge near → Path far)
• Lane lines and road edges use the wider minimal-view geometry with a stronger glow halo
• Accent tints the torque-bar fill (the high-torque yellow→orange warning blend is preserved) and the MICI set-speed value
• The vision-lead chevron and its info box follow LeadMarker (radar leads stay blue)

UI details

• C3X: the Theme row opens a scrollable option dialog (same pattern as the preferred-network picker), so any number of packs fits.
• MICI: a cycling toggle built from the same entries; its indicator pills auto-compress.
• soundd hot-reloads sounds when the selection changes (only while no alert is playing).

Assets

Bundled palettes are original. Steering-wheel icons are from OpenMoji (CC BY-SA 4.0, credited in selfdrive/assets/bp_themes/README.md). Total asset weight ~2.5 MB, stored as regular git blobs (exempted from LFS in .gitattributes, matching the existing BP asset pattern).

Testing

• Selector state logic (Off / 8-Bit Racer / pack, case-insensitivity, unknown-pack fallback) verified via script on this exact commit
• Both UI layouts boot clean with a pack active (WSL, replay environment)
• scons builds after the BPThemePack params key addition
• Pack integrity check: all ten packs load colors + wheel icon

Screenshots

Captured on the PC preview (replay of a real drive, Minimal Driving View). Theme switching is live — no restart between these. Everything you see beyond the road — the falling snow, string lights, garlands, leaves, bats, the pumpkin — is procedural: zero image assets in the diff.

Halloween

Christmas

8-Bit Racer (same selector)

New Year's	Valentine's
St. Patrick's	April Fools
Easter	Cinco de Mayo
Fourth of July	Thanksgiving

comma four (MICI) layout

🤖 Generated with Claude Code

[ghbarker]

Superseded by a fresh PR with the v2 scene system and updated screenshots — same branch, clean two-commit history (original selector + scenes). New PR follows momentarily.