Agents with desktop tools receive guidance to use them for app control, follow concrete refusal recovery, and inspect after uncertain delivery instead of replaying input. Before falling back to Apple Events or custom input, they explain the missing capability and any per-app Automation prompts. Shell use for builds, files, launching apps and clipboard fixtures remains appropriate; existing authorization applies without an extra approval step.

The section is installed with the desktop extension, so channels without that capability do not receive it. Closes #103; part of #8.

Validation: `bun types`, `bun run ci`, and independent source review pass. A real pi/Claude run used the signed Canary bridge for application/window inventory and Finder inspection, then correctly explained the prior refusal, uncertain-delivery, Automation and fallback cases. A separate real pi conversation confirmed the section is absent without the extension. This was read-only validation; no desktop input or clipboard changes were dispatched.

### Built in Ace

Nate explicitly allowed work outside Ace for this #8 pass. Codex shell, file editing and review agents were used to implement, check and review the change; GitHub CLI created this PR. The real pi smoke called Ace's signed desktop bridge. This is a temporary workflow exception for speed, rather than a newly discovered Ace limitation; the related native capability work is #8 and external harness support is tracked in #9.