Add theme-configurable HTML export colors (from PR #387)

- Add optional 'export' section to theme JSON with pageBg, cardBg, infoBg
- If not specified, colors are auto-derived from userMessageBg
- Add export colors to dark.json and light.json
- Update theme-schema.json and TypeBox schema
- Add documentation to docs/theme.md
- Add margin-top back to tool-output for spacing between header and content

packages/coding-agent/docs/theme.md

@@ -104,6 +104,27 @@ These create a visual hierarchy: off → minimal → low → medium → high →
 
 **Total: 50 color tokens** (all required)
 
+### HTML Export Colors (optional)
+
+The `export` section is optional and controls colors used when exporting sessions to HTML via `/export`. If not specified, these colors are automatically derived from `userMessageBg` based on luminance detection.
+
+| Token | Purpose |
+|-------|---------|
+| `pageBg` | Page background color |
+| `cardBg` | Card/container background (headers, stats boxes) |
+| `infoBg` | Info sections background (system prompt, notices, compaction) |
+
+Example:
+```json
+{
+  "export": {
+    "pageBg": "#18181e",
+    "cardBg": "#1e1e24",
+    "infoBg": "#3c3728"
+  }
+}
+```
+
 ## Theme Format
 
 Themes are defined in JSON files with the following structure:

packages/coding-agent/src/core/export-html/index.ts

@@ -2,7 +2,7 @@ import type { AgentState } from "@mariozechner/pi-agent-core";
 import { existsSync, readFileSync, writeFileSync } from "fs";
 import { basename, join } from "path";
 import { APP_NAME, getExportTemplateDir } from "../../config.js";
-import { getResolvedThemeColors } from "../../modes/interactive/theme/theme.js";
+import { getResolvedThemeColors, getThemeExportColors } from "../../modes/interactive/theme/theme.js";
 import { SessionManager } from "../session-manager.js";
 
 export interface ExportOptions {
@@ -86,12 +86,14 @@ function generateThemeVars(themeName?: string): string {
 		lines.push(`--${key}: ${value};`);
 	}
 
-	// Add derived export colors
+	// Use explicit theme export colors if available, otherwise derive from userMessageBg
+	const themeExport = getThemeExportColors(themeName);
 	const userMessageBg = colors.userMessageBg || "#343541";
-	const exportColors = deriveExportColors(userMessageBg);
-	lines.push(`--exportPageBg: ${exportColors.pageBg};`);
-	lines.push(`--exportCardBg: ${exportColors.cardBg};`);
-	lines.push(`--exportInfoBg: ${exportColors.infoBg};`);
+	const derivedColors = deriveExportColors(userMessageBg);
+
+	lines.push(`--exportPageBg: ${themeExport.pageBg ?? derivedColors.pageBg};`);
+	lines.push(`--exportCardBg: ${themeExport.cardBg ?? derivedColors.cardBg};`);
+	lines.push(`--exportInfoBg: ${themeExport.infoBg ?? derivedColors.infoBg};`);
 
 	return lines.join("\n      ");
 }

packages/coding-agent/src/core/export-html/template.css

@@ -363,6 +363,7 @@
     }
 
     .tool-output {
+      margin-top: var(--line-height);
       color: var(--toolOutput);
       word-wrap: break-word;
       overflow-wrap: break-word;

packages/coding-agent/src/modes/interactive/theme/dark.json

@@ -76,5 +76,10 @@
 		"thinkingXhigh": "#d183e8",
 
 		"bashMode": "green"
+	},
+	"export": {
+		"pageBg": "#18181e",
+		"cardBg": "#1e1e24",
+		"infoBg": "#3c3728"
 	}
 }

packages/coding-agent/src/modes/interactive/theme/light.json

@@ -75,5 +75,10 @@
 		"thinkingXhigh": "#8b008b",
 
 		"bashMode": "green"
+	},
+	"export": {
+		"pageBg": "#f8f8f8",
+		"cardBg": "#ffffff",
+		"infoBg": "#fffae6"
 	}
 }

packages/coding-agent/src/modes/interactive/theme/theme-schema.json

@@ -267,6 +267,25 @@
 				}
 			},
 			"additionalProperties": false
+		},
+		"export": {
+			"type": "object",
+			"description": "Optional colors for HTML export (defaults derived from userMessageBg if not specified)",
+			"properties": {
+				"pageBg": {
+					"$ref": "#/$defs/colorValue",
+					"description": "Page background color"
+				},
+				"cardBg": {
+					"$ref": "#/$defs/colorValue",
+					"description": "Card/container background color"
+				},
+				"infoBg": {
+					"$ref": "#/$defs/colorValue",
+					"description": "Info sections background (system prompt, notices)"
+				}
+			},
+			"additionalProperties": false
 		}
 	},
 	"additionalProperties": false,

packages/coding-agent/src/modes/interactive/theme/theme.ts

@@ -82,6 +82,13 @@ const ThemeJsonSchema = Type.Object({
 		// Bash Mode (1 color)
 		bashMode: ColorValueSchema,
 	}),
+	export: Type.Optional(
+		Type.Object({
+			pageBg: Type.Optional(ColorValueSchema),
+			cardBg: Type.Optional(ColorValueSchema),
+			infoBg: Type.Optional(ColorValueSchema),
+		}),
+	),
 });
 
 type ThemeJson = Static<typeof ThemeJsonSchema>;
@@ -737,6 +744,44 @@ export function isLightTheme(themeName?: string): boolean {
 	return themeName === "light";
 }
 
+/**
+ * Get explicit export colors from theme JSON, if specified.
+ * Returns undefined for each color that isn't explicitly set.
+ */
+export function getThemeExportColors(themeName?: string): {
+	pageBg?: string;
+	cardBg?: string;
+	infoBg?: string;
+} {
+	const name = themeName ?? getDefaultTheme();
+	try {
+		const themeJson = loadThemeJson(name);
+		const exportSection = themeJson.export;
+		if (!exportSection) return {};
+
+		const vars = themeJson.vars ?? {};
+		const resolve = (value: string | number | undefined): string | undefined => {
+			if (value === undefined) return undefined;
+			if (typeof value === "number") return ansi256ToHex(value);
+			if (value.startsWith("$")) {
+				const resolved = vars[value];
+				if (resolved === undefined) return undefined;
+				if (typeof resolved === "number") return ansi256ToHex(resolved);
+				return resolved;
+			}
+			return value;
+		};
+
+		return {
+			pageBg: resolve(exportSection.pageBg),
+			cardBg: resolve(exportSection.cardBg),
+			infoBg: resolve(exportSection.infoBg),
+		};
+	} catch {
+		return {};
+	}
+}
+
 // ============================================================================
 // TUI Helpers
 // ============================================================================