diff --git a/.cursor/skills/theme-authoring/SKILL.md b/.cursor/skills/theme-authoring/SKILL.md
new file mode 100644
index 00000000..58de7286
--- /dev/null
+++ b/.cursor/skills/theme-authoring/SKILL.md
@@ -0,0 +1,96 @@
+---
+name: theme-authoring
+description: Creates BetterSEQTA+ custom themes as `.theme.json` files for import or publishing to the BetterSEQTA theme store. Use when the user asks to make a new theme, adjust theme colors/CSS, or prepare a theme JSON for upload.
+---
+
+# Theme authoring (BetterSEQTA+)
+
+## Goal
+Produce a valid `*.theme.json` file that BetterSEQTA+ can install (via theme import or store download).
+
+## Output contract
+Return:
+- The final theme JSON (ready to save as `my-theme.theme.json`)
+- A short list of the main palette values used (accent + background + text)
+
+## Theme JSON schema (practical)
+Required keys:
+- `id`: string (stable identifier; use kebab-case, e.g. `banana-theme`)
+- `name`: string (display name)
+- `description`: string
+- `defaultColour`: string CSS color (e.g. `rgb(...)` or `#RRGGBB`)
+- `CanChangeColour`: boolean
+- `CustomCSS`: string (CSS applied as a `<style>` tag)
+
+Common optional keys:
+- `hideThemeName`: boolean
+- `forceTheme`: boolean (when true, the theme forces light/dark)
+- `forceDark`: boolean (when forcing, `true` = dark, `false` = light)
+- `images`: array of `{ id, variableName, data }` where `data` is base64 PNG (no prefix required, but allowed)
+- `coverImage`: base64 image string (optional)
+- `adaptiveCssVariables`: string[] (advanced; see below)
+
+## Workflow
+### 1) Pick a theme concept + palette
+Decide:
+- **Accent**: set as `defaultColour`
+- **Surfaces**: `--background-primary`, `--background-secondary`
+- **Text**: set `--theme-fg-parts` to a readable RGB triple
+
+If the theme is intended to be “bright” and friendly, default to **forced light**:
+- `forceTheme: true`, `forceDark: false`
+
+If it’s intended to be “night/dark”, default to **forced dark**:
+- `forceTheme: true`, `forceDark: true`
+
+### 2) Write `CustomCSS`
+Use a consistent, minimal set of overrides:
+- In `:root` set:
+  - `--background-primary`, `--background-secondary`
+  - `--theme-offset-bg`, `--theme-offset-bg-more` (slightly darker/lighter than secondary)
+  - `--theme-bg-parts`, `--theme-sel-bg-parts`, `--theme-fg-parts` (RGB triples)
+- Set the page background on:
+  - `html, body, #container, #content`
+  - Use 2–3 subtle `radial-gradient(...)` layers + a `linear-gradient(...)`
+  - Finish with `, var(--background) !important;` so custom backgrounds still work
+
+Recommended template (edit values and gradient stops):
+
+```json
+{
+  "id": "my-theme",
+  "name": "My Theme",
+  "description": "One-line vibe description.",
+  "defaultColour": "rgb(123, 100, 200)",
+  "CanChangeColour": true,
+  "hideThemeName": false,
+  "forceTheme": true,
+  "forceDark": false,
+  "CustomCSS": ":root {\\n  --background-primary: rgb(255, 255, 255) !important;\\n  --background-secondary: rgb(235, 235, 235) !important;\\n  --theme-offset-bg: rgb(245, 245, 245) !important;\\n  --theme-offset-bg-more: rgb(225, 225, 225) !important;\\n  --theme-bg-parts: 255, 255, 255 !important;\\n  --theme-sel-bg-parts: 123, 100, 200 !important;\\n  --theme-fg-parts: 20, 20, 20 !important;\\n}\\n\\nhtml,\\nbody,\\n#container,\\n#content {\\n  background-image:\\n    radial-gradient(circle at 18% 18%, rgb(123 100 200 / 20%) 0%, transparent 40%),\\n    radial-gradient(circle at 82% 78%, rgb(123 100 200 / 14%) 0%, transparent 46%),\\n    linear-gradient(145deg, rgb(255 255 255) 0%, rgb(245 245 245) 55%, rgb(235 235 235) 100%),\\n    var(--background) !important;\\n  background-size: auto, auto, auto, cover !important;\\n  background-position: center, center, center, center !important;\\n  background-repeat: no-repeat !important;\\n  background-attachment: fixed !important;\\n}\\n\"\n+}
+```
+
+### 3) Validate mentally (fast checks)
+- **Contrast**: `--theme-fg-parts` must be readable on both primary and secondary backgrounds.
+- **Forcing**: if `forceTheme: true`, ensure `forceDark` matches the palette.
+- **No hard dependency on images** unless you include `images`.
+
+### 4) Hand off
+Name the file as: `<id>.theme.json` (e.g. `banana.theme.json`).
+
+## Advanced: `adaptiveCssVariables` (optional)
+Use only when you want the theme to react cleanly to **Adaptive Theme Colour** in BetterSEQTA+.
+
+What it does:
+- It requests the app to write values derived from the current `--better-main` into CSS custom properties you list.
+- Supports channel bindings by suffix:
+  - `--my-var:r` (red channel as `0..255`)
+  - `--my-var:g` (green channel)
+  - `--my-var:b` (blue channel)
+  - `--my-var` (full colour string)
+
+When to use:
+- Your theme does math/mixing in CSS and needs stable numeric channels.
+
+When NOT to use:
+- Most themes. If your theme looks good with a fixed palette, omit it.
+
diff --git a/src/plugins/built-in/themes/theme-manager.ts b/src/plugins/built-in/themes/theme-manager.ts
index b3bc490a..e37f90e5 100644
--- a/src/plugins/built-in/themes/theme-manager.ts
+++ b/src/plugins/built-in/themes/theme-manager.ts
@@ -25,7 +25,9 @@ type ThemeContent = {
   CanChangeColour?: boolean;
   CustomCSS?: string;
   hideThemeName?: boolean;
+  forceTheme?: boolean;
   forceDark?: boolean;
+  adaptiveCssVariables?: string[];
   images?: { id: string; variableName: string; data: string }[]; // data: base64
 };
 
@@ -35,7 +37,7 @@ export type InstallThemeMeta = {
   serverUpdatedAtSec?: number;
   forceTheme?: boolean;
   adaptiveCssVariables?: string[];
-  images: { id: string; variableName: string; data: string }[]; // data: base64
+  images?: { id: string; variableName: string; data: string }[]; // data: base64
 };
 
 export class ThemeManager {