AXI-172: Add Desktop Update Control cockpit

apps/desktop/src/plugins/README.md

@@ -11,6 +11,15 @@ in the companion
 [`hermes-example-plugins`](https://github.com/NousResearch/hermes-example-plugins)
 repo instead.
 
+The Axiom fork's bundled **Update Control** plugin belongs here because it
+dogfoods the fork-local `host.updates` facade and provides a shipped management
+surface. It reads detached local-client and active-backend snapshots, including
+deploy/upstream disparity when core publishes it, then hands the active target
+to the core-owned native updater. Do not add direct checks, branch writes, pull,
+merge, install, restart, or relaunch mutation to plugin code; polling,
+confirmation, dirty-tree policy, deploy reconciliation, and process handoff
+stay in core.
+
 User- and agent-authored plugins load at runtime from
 `$HERMES_HOME/desktop-plugins/<name>/plugin.js` (the disk door) — see the
 `hermes-desktop-plugins` skill.

apps/desktop/src/plugins/update-control/model.test.ts

@@ -0,0 +1,24 @@
+import { describe, expect, it } from 'vitest'
+
+import { friendlyError, hasUpdate, shortSha } from './model'
+
+describe('update summaries', () => {
+  it('treats either the explicit flag or a positive behind count as an update', () => {
+    expect(hasUpdate({ supported: true, updateAvailable: true })).toBe(true)
+    expect(hasUpdate({ supported: true, behind: 2 })).toBe(true)
+    expect(hasUpdate({ supported: false, behind: 2 })).toBe(false)
+    expect(hasUpdate({ supported: true, behind: 0 })).toBe(false)
+  })
+
+  it('shortens commit identifiers without inventing one', () => {
+    expect(shortSha('1234567890abcdef')).toBe('12345678')
+    expect(shortSha('abc')).toBe('abc')
+    expect(shortSha()).toBe('—')
+  })
+
+  it('turns unknown failures into useful general-purpose copy', () => {
+    expect(friendlyError(new Error('bridge offline'))).toBe('bridge offline')
+    expect(friendlyError('timeout')).toBe('timeout')
+    expect(friendlyError(null)).toBe('Update information is unavailable right now.')
+  })
+})

apps/desktop/src/plugins/update-control/model.ts

@@ -0,0 +1,25 @@
+export interface UpdateSummary {
+  supported?: boolean
+  updateAvailable?: boolean
+  behind?: number
+}
+
+export function hasUpdate(status: UpdateSummary | null | undefined): boolean {
+  return status?.supported === true && (status.updateAvailable === true || (status.behind ?? 0) > 0)
+}
+
+export function shortSha(value?: null | string): string {
+  return value ? value.slice(0, 8) : '—'
+}
+
+export function friendlyError(error: unknown): string {
+  if (error instanceof Error && error.message.trim()) {
+    return error.message
+  }
+
+  if (typeof error === 'string' && error.trim()) {
+    return error
+  }
+
+  return 'Update information is unavailable right now.'
+}

apps/desktop/src/plugins/update-control/plugin.test.tsx

@@ -0,0 +1,33 @@
+import { describe, expect, it, vi } from 'vitest'
+
+import plugin from './plugin'
+
+describe('Update Control plugin registration', () => {
+  it('ships opt-in and contributes the page, navigation, status, and palette action', () => {
+    const registerMany = vi.fn()
+
+    plugin.register({ registerMany } as never)
+
+    expect(plugin.defaultEnabled).toBe(false)
+    expect(plugin.id).toBe('update-control')
+
+    const contributions = registerMany.mock.calls[0]?.[0] as Array<{
+      area: string
+      data?: { label?: string; path?: string }
+      id: string
+      render?: unknown
+    }>
+
+    expect(contributions.map(contribution => contribution.id)).toEqual(['page', 'nav', 'status', 'open'])
+    expect(contributions.find(contribution => contribution.id === 'page')).toMatchObject({
+      area: 'routes',
+      data: { path: '/update-control' }
+    })
+    expect(contributions.find(contribution => contribution.id === 'nav')).toMatchObject({
+      area: 'sidebar.nav',
+      data: { label: 'Update Control', path: '/update-control' }
+    })
+    expect(contributions.find(contribution => contribution.id === 'status')?.render).toBeTypeOf('function')
+    expect(contributions.find(contribution => contribution.id === 'open')?.data?.label).toBe('Update Control: Open')
+  })
+})