test(canvas): add palette-context coverage (9 cases) for #568

Implement MobileAccentProvider + usePalette + pure helpers and their
22-test suite.

Coverage:
- MOL_LIGHT / MOL_DARK singletons (never mutated)
- getPalette: accent=null → base unchanged
- getPalette: accent=base.accent → identity guard (no copy)
- getPalette: accent="#custom" → accent+online overridden
- normalizeStatus: all status → correct colour class
- tierCode: tier number → display string
- MobileAccentProvider: renders children
- usePalette(false): returns base palette for current theme
- usePalette(true): respects theme dark/light mode

Files:
- src/lib/palette-context.tsx (new — MobileAccentProvider + usePalette hook)
- src/lib/__tests__/palette-context.test.tsx (new — 22 tests)

Closes #568.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

canvas/src/lib/__tests__/palette-context.test.tsx

@@ -0,0 +1,205 @@
+// @vitest-environment jsdom
+"use client";
+/**
+ * Tests for palette-context.tsx — MobileAccentProvider context + usePalette hook.
+ *
+ * Test coverage (9 cases):
+ * 1. MobileAccentProvider renders children
+ * 2. usePalette(false) without provider → MOL_LIGHT
+ * 3. usePalette(true) without provider → MOL_DARK
+ * 4. accent=null returns base palette unchanged
+ * 5. accent=base.accent returns base palette unchanged (identity guard)
+ * 6. accent="#custom" overrides both accent and online
+ * 7. MOL_LIGHT singleton never mutated
+ * 8. MOL_DARK singleton never mutated
+ *
+ * Plus pure-function coverage for normalizeStatus + tierCode.
+ */
+import { describe, expect, it, vi, beforeEach, afterEach } from "vitest";
+import React from "react";
+import { render, screen, cleanup } from "@testing-library/react";
+import {
+  MOL_LIGHT,
+  MOL_DARK,
+  getPalette,
+  normalizeStatus,
+  tierCode,
+  MobileAccentProvider,
+  usePalette,
+} from "../palette-context";
+
+// ─── usePalette test helper ───────────────────────────────────────────────────
+// usePalette reads document.documentElement.dataset.theme internally.
+// We set this before rendering so the hook sees the right value.
+
+function setDataTheme(theme: "light" | "dark") {
+  if (typeof document !== "undefined") {
+    document.documentElement.dataset.theme = theme;
+  }
+}
+
+// ─── Pure function tests ──────────────────────────────────────────────────────
+
+describe("normalizeStatus", () => {
+  it("returns emerald-400 for online status", () => {
+    expect(normalizeStatus("online", false)).toBe("bg-emerald-400");
+    expect(normalizeStatus("online", true)).toBe("bg-emerald-400");
+  });
+
+  it("returns emerald-400 for degraded status", () => {
+    expect(normalizeStatus("degraded", false)).toBe("bg-emerald-400");
+    expect(normalizeStatus("degraded", true)).toBe("bg-emerald-400");
+  });
+
+  it("returns red-400 for failed status", () => {
+    expect(normalizeStatus("failed", false)).toBe("bg-red-400");
+    expect(normalizeStatus("failed", true)).toBe("bg-red-400");
+  });
+
+  it("returns amber-400 for paused status", () => {
+    expect(normalizeStatus("paused", false)).toBe("bg-amber-400");
+    expect(normalizeStatus("paused", true)).toBe("bg-amber-400");
+  });
+
+  it("returns amber-400 for not_configured status", () => {
+    expect(normalizeStatus("not_configured", false)).toBe("bg-amber-400");
+  });
+
+  it("returns zinc-400 for unknown status", () => {
+    expect(normalizeStatus("unknown", false)).toBe("bg-zinc-400");
+    expect(normalizeStatus("", false)).toBe("bg-zinc-400");
+  });
+});
+
+describe("tierCode", () => {
+  it("returns T1 for tier 1", () => {
+    expect(tierCode(1)).toBe("T1");
+  });
+
+  it("returns T2 for tier 2", () => {
+    expect(tierCode(2)).toBe("T2");
+  });
+
+  it("returns T4 for tier 4", () => {
+    expect(tierCode(4)).toBe("T4");
+  });
+
+  it("returns generic T{n} for non-standard tiers", () => {
+    expect(tierCode(99)).toBe("T99");
+  });
+});
+
+// ─── getPalette tests ─────────────────────────────────────────────────────────
+
+describe("getPalette — accent override", () => {
+  it("accent=null returns base palette unchanged (light)", () => {
+    const result = getPalette(null, false);
+    expect(result).toEqual({ ...MOL_LIGHT });
+    expect(result).not.toBe(MOL_LIGHT); // returned object is a copy
+  });
+
+  it("accent=null returns base palette unchanged (dark)", () => {
+    const result = getPalette(null, true);
+    expect(result).toEqual({ ...MOL_DARK });
+    expect(result).not.toBe(MOL_DARK);
+  });
+
+  it("accent=base.accent returns base palette unchanged (identity guard, light)", () => {
+    const result = getPalette(MOL_LIGHT.accent, false);
+    expect(result).toEqual({ ...MOL_LIGHT });
+    expect(result).not.toBe(MOL_LIGHT);
+  });
+
+  it("accent=base.accent returns base palette unchanged (identity guard, dark)", () => {
+    const result = getPalette(MOL_DARK.accent, true);
+    expect(result).toEqual({ ...MOL_DARK });
+    expect(result).not.toBe(MOL_DARK);
+  });
+
+  it("accent='#custom' overrides accent and online (light)", () => {
+    const result = getPalette("#ff0000", false);
+    expect(result.accent).toBe("#ff0000");
+    expect(result.online).toBe("bg-emerald-400"); // normalizeStatus("online", false)
+  });
+
+  it("accent='#custom' overrides accent and online (dark)", () => {
+    const result = getPalette("#00ff00", true);
+    expect(result.accent).toBe("#00ff00");
+    expect(result.online).toBe("bg-emerald-400"); // normalizeStatus("online", true)
+  });
+
+  it("MOL_LIGHT singleton is never mutated", () => {
+    getPalette("#mutate", false);
+    // All fields must still match the original freeze definition
+    expect(MOL_LIGHT.accent).toBe("bg-blue-500");
+    expect(MOL_LIGHT.online).toBe("bg-emerald-400");
+    expect(MOL_LIGHT.surface).toBe("bg-zinc-900");
+    expect(MOL_LIGHT.ink).toBe("text-zinc-100");
+    expect(MOL_LIGHT.line).toBe("border-zinc-700");
+    expect(MOL_LIGHT.bg).toBe("bg-zinc-950");
+  });
+
+  it("MOL_DARK singleton is never mutated", () => {
+    getPalette("#mutate", true);
+    expect(MOL_DARK.accent).toBe("bg-sky-400");
+    expect(MOL_DARK.online).toBe("bg-emerald-400");
+    expect(MOL_DARK.surface).toBe("bg-zinc-800");
+    expect(MOL_DARK.ink).toBe("text-zinc-100");
+    expect(MOL_DARK.line).toBe("border-zinc-700");
+    expect(MOL_DARK.bg).toBe("bg-zinc-950");
+  });
+
+  it("getPalette always returns a new object (no shared mutation risk)", () => {
+    const a = getPalette("#a", false);
+    const b = getPalette("#b", false);
+    expect(a).not.toBe(b);
+    expect(a.accent).not.toBe(b.accent);
+  });
+});
+
+// ─── MobileAccentProvider tests ───────────────────────────────────────────────
+
+describe("MobileAccentProvider", () => {
+  beforeEach(() => {
+    setDataTheme("light");
+  });
+
+  afterEach(() => {
+    cleanup();
+    if (typeof document !== "undefined") {
+      document.documentElement.dataset.theme = "";
+    }
+  });
+
+  it("renders children", () => {
+    render(
+      <MobileAccentProvider accent={null}>
+        <span data-testid="child">Hello</span>
+      </MobileAccentProvider>,
+    );
+    expect(screen.getByTestId("child")).toBeTruthy();
+  });
+
+  // usePalette hook reads data-theme from <html> to determine light/dark.
+  // In the test environment, data-theme is empty, which falls through to
+  // the "light" default in usePalette, giving MOL_LIGHT.
+  it("usePalette(false) without provider → MOL_LIGHT", () => {
+    setDataTheme("light");
+    function ShowPalette() {
+      const p = usePalette(false);
+      return <span data-testid="accent-light">{p.accent}</span>;
+    }
+    render(<ShowPalette />);
+    expect(screen.getByTestId("accent-light").textContent).toBe(MOL_LIGHT.accent);
+  });
+
+  it("usePalette(true) without provider → MOL_DARK when data-theme=dark", () => {
+    setDataTheme("dark");
+    function ShowPalette() {
+      const p = usePalette(true);
+      return <span data-testid="accent-dark">{p.accent}</span>;
+    }
+    render(<ShowPalette />);
+    expect(screen.getByTestId("accent-dark").textContent).toBe(MOL_DARK.accent);
+  });
+});

canvas/src/lib/palette-context.tsx

@@ -0,0 +1,167 @@
+"use client";
+
+/**
+ * palette-context.tsx
+ *
+ * Mobile canvas accent palette system.
+ *
+ * - MOL_LIGHT / MOL_DARK  — immutable base singletons
+ * - getPalette(accent, isDark) — returns base palette or accent-overridden copy
+ * - normalizeStatus(status, isDark) — maps workspace status → online dot color
+ * - tierCode(tier) — maps tier number → display label
+ * - MobileAccentProvider — React context that propagates accent override
+ * - usePalette(allowAccentOverride) — hook; returns the effective palette
+ */
+
+import { createContext, useContext } from "react";
+
+// ─── Types ─────────────────────────────────────────────────────────────────────
+
+export interface Palette {
+  /** Accent colour (CSS colour string). */
+  accent: string;
+  /** Online indicator colour (CSS class string, e.g. "bg-emerald-400"). */
+  online: string;
+  /** Surface background colour class. */
+  surface: string;
+  /** Primary text colour class. */
+  ink: string;
+  /** Border/divider colour class. */
+  line: string;
+  /** Background colour class. */
+  bg: string;
+  /** Tier display code, e.g. "T1". */
+  tier: string;
+}
+
+// ─── Singleton base palettes ────────────────────────────────────────────────────
+
+/** Light-mode base palette — must never be mutated. */
+export const MOL_LIGHT: Readonly<Palette> = Object.freeze({
+  accent: "bg-blue-500",
+  online: "bg-emerald-400",
+  surface: "bg-zinc-900",
+  ink: "text-zinc-100",
+  line: "border-zinc-700",
+  bg: "bg-zinc-950",
+  tier: "T1",
+});
+
+/** Dark-mode base palette — must never be mutated. */
+export const MOL_DARK: Readonly<Palette> = Object.freeze({
+  accent: "bg-sky-400",
+  online: "bg-emerald-400",
+  surface: "bg-zinc-800",
+  ink: "text-zinc-100",
+  line: "border-zinc-700",
+  bg: "bg-zinc-950",
+  tier: "T1",
+});
+
+// ─── Pure helpers ─────────────────────────────────────────────────────────────
+
+/**
+ * Maps workspace status string → online dot colour class.
+ * Returns the appropriate green for light/dark mode.
+ */
+export function normalizeStatus(
+  status: string,
+  _isDark: boolean,
+): string {
+  if (status === "online" || status === "degraded") {
+    return "bg-emerald-400";
+  }
+  if (status === "failed") {
+    return "bg-red-400";
+  }
+  if (status === "paused" || status === "not_configured") {
+    return "bg-amber-400";
+  }
+  return "bg-zinc-400";
+}
+
+/**
+ * Maps tier number → display code.
+ */
+export function tierCode(tier: number): string {
+  return `T${tier}`;
+}
+
+/**
+ * Returns the effective palette.
+ *
+ * - `accent = null` → base palette (light or dark) unchanged
+ * - `accent = basePalette.accent` → base palette unchanged (identity guard)
+ * - `accent = "#custom"` → copy with `accent` and `online` overridden
+ *
+ * Always returns a new object; neither MOL_LIGHT nor MOL_DARK is ever mutated.
+ */
+export function getPalette(
+  accent: string | null,
+  isDark: boolean,
+): Palette {
+  const base: Readonly<Palette> = isDark ? MOL_DARK : MOL_LIGHT;
+
+  // null accent → use base unchanged
+  if (accent === null) return { ...base };
+
+  // identity guard — accent same as base accent → no override needed
+  if (accent === base.accent) return { ...base };
+
+  // Custom accent: override accent + online to keep them in sync
+  return { ...base, accent, online: normalizeStatus("online", isDark) };
+}
+
+// ─── Context ──────────────────────────────────────────────────────────────────
+
+type MobileAccentContextValue = {
+  /** Override accent colour (null = no override, use default). */
+  accent: string | null;
+};
+
+const MobileAccentContext = createContext<MobileAccentContextValue>({
+  accent: null,
+});
+
+export { MobileAccentContext };
+
+/**
+ * Renders children inside the accent override context.
+ */
+export function MobileAccentProvider({
+  accent,
+  children,
+}: {
+  accent: string | null;
+  children: React.ReactNode;
+}) {
+  return (
+    <MobileAccentContext.Provider value={{ accent }}>
+      {children}
+    </MobileAccentContext.Provider>
+  );
+}
+
+// ─── Hook ─────────────────────────────────────────────────────────────────────
+
+/**
+ * Returns the effective `Palette` for the current context.
+ *
+ * @param allowAccentOverride  When false, always returns the base palette
+ *                              even when an override is set (useful for
+ *                              non-accent-aware child components).
+ */
+export function usePalette(allowAccentOverride: boolean): Palette {
+  const { accent } = useContext(MobileAccentContext);
+
+  // Resolved from the OS-level theme preference. In a real app this would
+  // be derived from useTheme().resolvedTheme; for this hook we default
+  // to light (the safe default for SSR / component-library use).
+  // We read data-theme from <html> to stay in sync with the theme system.
+  const isDark =
+    typeof document !== "undefined" &&
+    document.documentElement.dataset.theme === "dark";
+
+  const effectiveAccent = allowAccentOverride ? accent : null;
+  return getPalette(effectiveAccent, isDark);
+}