diff --git a/ui-electrobun/tests/unit/plugin-store.test.ts b/ui-electrobun/tests/unit/plugin-store.test.ts
new file mode 100644
index 0000000..b92aae4
--- /dev/null
+++ b/ui-electrobun/tests/unit/plugin-store.test.ts
@@ -0,0 +1,191 @@
+// Tests for Electrobun plugin-store — pure logic.
+// Uses bun:test. Tests command registry, event bus, and permission validation.
+
+import { describe, it, expect, beforeEach } from 'bun:test';
+
+// ── Replicated types ──────────────────────────────────────────────────────────
+
+interface PluginMeta {
+  id: string;
+  name: string;
+  version: string;
+  description: string;
+  main: string;
+  permissions: string[];
+  allowedOrigins?: string[];
+  maxRuntime?: number;
+}
+
+interface PluginCommand {
+  pluginId: string;
+  label: string;
+  callback: () => void;
+}
+
+// ── Replicated event bus ────────────────────────────────────────────────────
+
+type EventHandler = (data: unknown) => void;
+
+function createEventBus() {
+  const listeners = new Map<string, Set<EventHandler>>();
+  return {
+    on(event: string, handler: EventHandler): void {
+      let set = listeners.get(event);
+      if (!set) { set = new Set(); listeners.set(event, set); }
+      set.add(handler);
+    },
+    off(event: string, handler: EventHandler): void {
+      listeners.get(event)?.delete(handler);
+    },
+    emit(event: string, data: unknown): void {
+      const set = listeners.get(event);
+      if (!set) return;
+      for (const handler of set) {
+        try { handler(data); } catch { /* swallow */ }
+      }
+    },
+    listenerCount(event: string): number {
+      return listeners.get(event)?.size ?? 0;
+    },
+  };
+}
+
+// ── Replicated command registry ──────────────────────────────────────────────
+
+function createCommandRegistry() {
+  let commands: PluginCommand[] = [];
+  return {
+    add(pluginId: string, label: string, callback: () => void): void {
+      commands = [...commands, { pluginId, label, callback }];
+    },
+    remove(pluginId: string): void {
+      commands = commands.filter(c => c.pluginId !== pluginId);
+    },
+    getAll(): PluginCommand[] { return commands; },
+    getByPlugin(pluginId: string): PluginCommand[] {
+      return commands.filter(c => c.pluginId === pluginId);
+    },
+  };
+}
+
+// ── Permission validation (replicated from plugin-host.ts) ──────────────────
+
+const VALID_PERMISSIONS = new Set(['palette', 'notifications', 'messages', 'events', 'network']);
+
+function validatePermissions(perms: string[]): { valid: boolean; invalid: string[] } {
+  const invalid = perms.filter(p => !VALID_PERMISSIONS.has(p));
+  return { valid: invalid.length === 0, invalid };
+}
+
+// ── Tests ───────────────────────────────────────────────────────────────────
+
+describe('command registry', () => {
+  let registry: ReturnType<typeof createCommandRegistry>;
+
+  beforeEach(() => {
+    registry = createCommandRegistry();
+  });
+
+  it('starts empty', () => {
+    expect(registry.getAll()).toHaveLength(0);
+  });
+
+  it('add registers a command', () => {
+    registry.add('my-plugin', 'Say Hello', () => {});
+    expect(registry.getAll()).toHaveLength(1);
+    expect(registry.getAll()[0].label).toBe('Say Hello');
+    expect(registry.getAll()[0].pluginId).toBe('my-plugin');
+  });
+
+  it('remove clears commands for a plugin', () => {
+    registry.add('p1', 'Cmd A', () => {});
+    registry.add('p1', 'Cmd B', () => {});
+    registry.add('p2', 'Cmd C', () => {});
+    registry.remove('p1');
+    expect(registry.getAll()).toHaveLength(1);
+    expect(registry.getAll()[0].pluginId).toBe('p2');
+  });
+
+  it('getByPlugin filters correctly', () => {
+    registry.add('p1', 'A', () => {});
+    registry.add('p2', 'B', () => {});
+    registry.add('p1', 'C', () => {});
+    expect(registry.getByPlugin('p1')).toHaveLength(2);
+    expect(registry.getByPlugin('p2')).toHaveLength(1);
+    expect(registry.getByPlugin('p3')).toHaveLength(0);
+  });
+});
+
+describe('event bus', () => {
+  let bus: ReturnType<typeof createEventBus>;
+
+  beforeEach(() => {
+    bus = createEventBus();
+  });
+
+  it('on registers listener', () => {
+    bus.on('test', () => {});
+    expect(bus.listenerCount('test')).toBe(1);
+  });
+
+  it('emit calls registered handlers', () => {
+    let received: unknown = null;
+    bus.on('data', (d) => { received = d; });
+    bus.emit('data', { value: 42 });
+    expect(received).toEqual({ value: 42 });
+  });
+
+  it('off removes listener', () => {
+    const handler = () => {};
+    bus.on('event', handler);
+    bus.off('event', handler);
+    expect(bus.listenerCount('event')).toBe(0);
+  });
+
+  it('emit does not throw for unregistered events', () => {
+    expect(() => bus.emit('nonexistent', null)).not.toThrow();
+  });
+
+  it('handler error is swallowed', () => {
+    bus.on('crash', () => { throw new Error('boom'); });
+    expect(() => bus.emit('crash', null)).not.toThrow();
+  });
+});
+
+describe('permission validation', () => {
+  it('accepts all valid permissions', () => {
+    const result = validatePermissions(['palette', 'notifications', 'messages', 'events', 'network']);
+    expect(result.valid).toBe(true);
+    expect(result.invalid).toHaveLength(0);
+  });
+
+  it('rejects unknown permissions', () => {
+    const result = validatePermissions(['palette', 'filesystem', 'exec']);
+    expect(result.valid).toBe(false);
+    expect(result.invalid).toEqual(['filesystem', 'exec']);
+  });
+
+  it('accepts empty permissions list', () => {
+    const result = validatePermissions([]);
+    expect(result.valid).toBe(true);
+  });
+});
+
+describe('plugin meta validation', () => {
+  it('maxRuntime defaults to 30 seconds', () => {
+    const meta: PluginMeta = {
+      id: 'test', name: 'Test', version: '1.0', description: 'desc',
+      main: 'index.js', permissions: [],
+    };
+    const maxRuntime = (meta.maxRuntime ?? 30) * 1000;
+    expect(maxRuntime).toBe(30_000);
+  });
+
+  it('allowedOrigins defaults to empty array', () => {
+    const meta: PluginMeta = {
+      id: 'test', name: 'Test', version: '1.0', description: 'desc',
+      main: 'index.js', permissions: ['network'],
+    };
+    expect(meta.allowedOrigins ?? []).toEqual([]);
+  });
+});
diff --git a/ui-electrobun/tests/unit/workspace-store.test.ts b/ui-electrobun/tests/unit/workspace-store.test.ts
new file mode 100644
index 0000000..be80662
--- /dev/null
+++ b/ui-electrobun/tests/unit/workspace-store.test.ts
@@ -0,0 +1,257 @@
+// Tests for Electrobun workspace-store — pure logic.
+// Uses bun:test. Tests CRUD operations and derived state logic.
+
+import { describe, it, expect, beforeEach } from 'bun:test';
+
+// ── Replicated types ──────────────────────────────────────────────────────────
+
+interface Project {
+  id: string;
+  name: string;
+  cwd: string;
+  accent: string;
+  status: 'running' | 'idle' | 'stalled';
+  costUsd: number;
+  tokens: number;
+  messages: Array<{ id: number; role: string; content: string }>;
+  provider?: string;
+  groupId?: string;
+  cloneOf?: string;
+}
+
+interface Group {
+  id: string;
+  name: string;
+  icon: string;
+  position: number;
+}
+
+const ACCENTS = [
+  'var(--ctp-mauve)', 'var(--ctp-sapphire)', 'var(--ctp-teal)',
+  'var(--ctp-peach)', 'var(--ctp-pink)', 'var(--ctp-lavender)',
+  'var(--ctp-green)', 'var(--ctp-blue)', 'var(--ctp-flamingo)',
+];
+
+// ── Pure store logic (no runes, no RPC) ──────────────────────────────────────
+
+function createWorkspaceState() {
+  let projects: Project[] = [];
+  let groups: Group[] = [{ id: 'dev', name: 'Development', icon: '1', position: 0 }];
+  let activeGroupId = 'dev';
+  let previousGroupId: string | null = null;
+
+  return {
+    getProjects: () => projects,
+    getGroups: () => groups,
+    getActiveGroupId: () => activeGroupId,
+    getMountedGroupIds: () => new Set([activeGroupId, ...(previousGroupId ? [previousGroupId] : [])]),
+    getActiveGroup: () => groups.find(g => g.id === activeGroupId) ?? groups[0],
+    getFilteredProjects: () => projects.filter(p => (p.groupId ?? 'dev') === activeGroupId),
+
+    addProject(name: string, cwd: string): void {
+      if (!name.trim() || !cwd.trim()) return;
+      const id = `p-${Date.now()}`;
+      const accent = ACCENTS[projects.length % ACCENTS.length];
+      projects = [...projects, {
+        id, name: name.trim(), cwd: cwd.trim(), accent,
+        status: 'idle', costUsd: 0, tokens: 0, messages: [],
+        provider: 'claude', groupId: activeGroupId,
+      }];
+    },
+
+    deleteProject(projectId: string): void {
+      projects = projects.filter(p => p.id !== projectId);
+    },
+
+    cloneCountForProject(projectId: string): number {
+      return projects.filter(p => p.cloneOf === projectId).length;
+    },
+
+    addGroup(name: string): void {
+      if (!name.trim()) return;
+      const id = `grp-${Date.now()}`;
+      const position = groups.length;
+      groups = [...groups, { id, name: name.trim(), icon: String(position + 1), position }];
+    },
+
+    setActiveGroup(id: string): void {
+      if (activeGroupId !== id) previousGroupId = activeGroupId;
+      activeGroupId = id;
+    },
+
+    getTotalCost: () => projects.reduce((s, p) => s + p.costUsd, 0),
+    getTotalTokens: () => projects.reduce((s, p) => s + p.tokens, 0),
+  };
+}
+
+// ── Tests ───────────────────────────────────────────────────────────────────
+
+describe('workspace store — project CRUD', () => {
+  let ws: ReturnType<typeof createWorkspaceState>;
+
+  beforeEach(() => {
+    ws = createWorkspaceState();
+  });
+
+  it('starts with empty projects', () => {
+    expect(ws.getProjects()).toHaveLength(0);
+  });
+
+  it('addProject creates a project with correct defaults', () => {
+    ws.addProject('My Project', '/home/user/code');
+    const projects = ws.getProjects();
+    expect(projects).toHaveLength(1);
+    expect(projects[0].name).toBe('My Project');
+    expect(projects[0].cwd).toBe('/home/user/code');
+    expect(projects[0].status).toBe('idle');
+    expect(projects[0].provider).toBe('claude');
+    expect(projects[0].groupId).toBe('dev');
+  });
+
+  it('addProject trims whitespace', () => {
+    ws.addProject('  padded  ', '  /path  ');
+    expect(ws.getProjects()[0].name).toBe('padded');
+    expect(ws.getProjects()[0].cwd).toBe('/path');
+  });
+
+  it('addProject rejects empty name or cwd', () => {
+    ws.addProject('', '/path');
+    ws.addProject('name', '');
+    ws.addProject('  ', '  ');
+    expect(ws.getProjects()).toHaveLength(0);
+  });
+
+  it('addProject assigns accent colors cyclically', () => {
+    for (let i = 0; i < ACCENTS.length + 1; i++) {
+      ws.addProject(`P${i}`, `/p${i}`);
+    }
+    const projects = ws.getProjects();
+    expect(projects[0].accent).toBe(ACCENTS[0]);
+    expect(projects[ACCENTS.length].accent).toBe(ACCENTS[0]); // wraps around
+  });
+
+  it('deleteProject removes the project', () => {
+    ws.addProject('A', '/a');
+    const id = ws.getProjects()[0].id;
+    ws.deleteProject(id);
+    expect(ws.getProjects()).toHaveLength(0);
+  });
+
+  it('deleteProject ignores unknown id', () => {
+    ws.addProject('A', '/a');
+    ws.deleteProject('nonexistent');
+    expect(ws.getProjects()).toHaveLength(1);
+  });
+
+  it('cloneCountForProject counts clones', () => {
+    ws.addProject('Main', '/main');
+    const mainId = ws.getProjects()[0].id;
+    // Manually add clones (addProject doesn't set cloneOf)
+    const projects = ws.getProjects();
+    projects.push({
+      id: 'clone-1', name: 'Clone 1', cwd: '/clone1', accent: ACCENTS[0],
+      status: 'idle', costUsd: 0, tokens: 0, messages: [],
+      cloneOf: mainId,
+    });
+    expect(ws.cloneCountForProject(mainId)).toBe(1);
+  });
+});
+
+describe('workspace store — group CRUD', () => {
+  let ws: ReturnType<typeof createWorkspaceState>;
+
+  beforeEach(() => {
+    ws = createWorkspaceState();
+  });
+
+  it('starts with default Development group', () => {
+    expect(ws.getGroups()).toHaveLength(1);
+    expect(ws.getGroups()[0].name).toBe('Development');
+  });
+
+  it('addGroup creates group with incremented position', () => {
+    ws.addGroup('Production');
+    expect(ws.getGroups()).toHaveLength(2);
+    expect(ws.getGroups()[1].name).toBe('Production');
+    expect(ws.getGroups()[1].position).toBe(1);
+    expect(ws.getGroups()[1].icon).toBe('2');
+  });
+
+  it('addGroup rejects empty name', () => {
+    ws.addGroup('');
+    ws.addGroup('  ');
+    expect(ws.getGroups()).toHaveLength(1);
+  });
+
+  it('activeGroup defaults to first group', () => {
+    expect(ws.getActiveGroup().id).toBe('dev');
+  });
+
+  it('setActiveGroup changes active and records previous', () => {
+    ws.addGroup('Staging');
+    const stagingId = ws.getGroups()[1].id;
+    ws.setActiveGroup(stagingId);
+    expect(ws.getActiveGroupId()).toBe(stagingId);
+    // mountedGroupIds should include both active and previous
+    expect(ws.getMountedGroupIds().has('dev')).toBe(true);
+    expect(ws.getMountedGroupIds().has(stagingId)).toBe(true);
+  });
+});
+
+describe('workspace store — derived state', () => {
+  let ws: ReturnType<typeof createWorkspaceState>;
+
+  beforeEach(() => {
+    ws = createWorkspaceState();
+  });
+
+  it('filteredProjects returns only active group projects', () => {
+    ws.addProject('DevProject', '/dev');
+    ws.addGroup('Staging');
+    const stagingId = ws.getGroups()[1].id;
+    ws.setActiveGroup(stagingId);
+    ws.addProject('StagingProject', '/staging');
+
+    // Switch back to dev
+    ws.setActiveGroup('dev');
+    const filtered = ws.getFilteredProjects();
+    expect(filtered).toHaveLength(1);
+    expect(filtered[0].name).toBe('DevProject');
+  });
+
+  it('mountedGroupIds only includes active + previous', () => {
+    ws.addGroup('G1');
+    ws.addGroup('G2');
+    const g1Id = ws.getGroups()[1].id;
+    const g2Id = ws.getGroups()[2].id;
+
+    ws.setActiveGroup(g1Id);
+    ws.setActiveGroup(g2Id);
+    const mounted = ws.getMountedGroupIds();
+    expect(mounted.size).toBe(2);
+    expect(mounted.has(g2Id)).toBe(true);   // active
+    expect(mounted.has(g1Id)).toBe(true);   // previous
+    expect(mounted.has('dev')).toBe(false);  // two switches ago — not mounted
+  });
+});
+
+describe('workspace store — aggregates', () => {
+  it('getTotalCost sums across projects', () => {
+    const ws = createWorkspaceState();
+    ws.addProject('A', '/a');
+    ws.addProject('B', '/b');
+    // Mutate costs directly
+    ws.getProjects()[0].costUsd = 1.50;
+    ws.getProjects()[1].costUsd = 2.75;
+    expect(ws.getTotalCost()).toBeCloseTo(4.25, 2);
+  });
+
+  it('getTotalTokens sums across projects', () => {
+    const ws = createWorkspaceState();
+    ws.addProject('A', '/a');
+    ws.addProject('B', '/b');
+    ws.getProjects()[0].tokens = 10000;
+    ws.getProjects()[1].tokens = 25000;
+    expect(ws.getTotalTokens()).toBe(35000);
+  });
+});