docs: add Remote Control (§9.22) — mobile access feature documentation

- New section 9.22 in ultimate-guide.md with full Remote Control coverage
- Cheatsheet: dedicated section + Features Méconnues + slash commands
- security-hardening.md: Part 7 Remote Control Security threat model
- machine-readable/reference.yaml: /rc, /remote-control, /mobile, subcommand
- Resource evaluation: 2026-02-25 (score 4/5, community feedback included)

Key original content vs official Anthropic docs:
- Slash commands (/new, /compact) broken in remote UI — undocumented
- tmux multi-session workaround for 1-session limit
- Community security analysis (RCE surface, CISO implications)

Research Preview — Pro/Max plans only (v2.1.51+)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

guide/security-hardening.md

@@ -833,4 +833,74 @@ Beyond securing Claude Code itself, Anthropic offers a dedicated vulnerability s
 
 ---
 
-*Version 1.1.0 | February 2026 | Part of [Claude Code Ultimate Guide](../README.md)*
+## Part 7: Remote Control Security {#remote-control-security}
+
+> **Feature context**: Remote Control (Research Preview, Feb 2026) allows controlling a local Claude Code session from a phone, tablet, or browser. Available on Pro and Max plans only.
+
+### Architecture
+
+```
+Local terminal ──HTTPS outbound──► Anthropic relay ──► Mobile/Browser
+ (execution)                        (relay only)        (control UI)
+```
+
+**Security properties:**
+- Zero inbound ports (reduces attack surface vs SSH tunnels or ngrok)
+- HTTPS only (encrypted in transit)
+- Session URL = short-lived authentication token
+- Execution stays 100% local
+
+### Threat Model
+
+| Threat | Risk | Mitigation |
+|--------|------|------------|
+| **Session URL leak** | Full terminal access for whoever holds the URL | Treat URL as password — don't share in Slack/logs/screenshots |
+| **RCE via remote commands** | Attacker who gets the URL can run commands if they approve tool calls | Per-command approval prompts on mobile (not foolproof against active attacker) |
+| **Corporate policy violation** | Personal Claude account on corporate machine routes traffic through Anthropic relay | Verify policy before enabling, even on personal plans |
+| **Persistent session exposure** | Long-running sessions increase window of exposure | Close sessions when done; ~10min auto-timeout on disconnect |
+| **Shared/untrusted workstation** | Session URL valid while session is open | Never run remote-control on shared machines |
+
+> **Community perspective**: Senior devs immediately noted: "C'est une sacrée RCE qu'ils introduisent là." The session URL is effectively a live key to an executing terminal. The per-command approval mechanism limits accidental execution but does not protect against a determined attacker who holds the URL and approves all prompts.
+
+### Best Practices
+
+```bash
+# 1. Don't auto-enable — activate only when needed
+#    Avoid: /config → auto-enable remote-control
+
+# 2. Use on a dedicated, hardened workstation
+#    Not on machines with access to production credentials or secrets
+
+# 3. Close the session when done
+#    Ctrl+C on local terminal, or dismiss from the mobile app
+
+# 4. Never share session URLs in team chats, tickets, or logs
+#    They are live access tokens while the session is active
+
+# 5. Prefer use on personal dev machines
+#    Not on corporate machines with elevated privileges
+```
+
+### Enterprise Considerations
+
+Remote Control is **not available** on Team or Enterprise plans. However:
+
+- Developers on personal Pro/Max accounts may use it on corporate hardware
+- The relay traffic (your commands and Claude's responses) passes through Anthropic infrastructure
+- If your organization has strict data residency requirements, treat Remote Control like any cloud-routed tool
+- Recommended: use only on a dedicated "sandbox" workstation without access to production systems
+
+### Comparison: Remote Control vs Alternatives
+
+| Method | Inbound ports | Data path | Risk level |
+|--------|---------------|-----------|------------|
+| **Remote Control** | None (outbound HTTPS) | Anthropic relay | Low-Medium |
+| **SSH + mobile terminal** | Yes (port 22) | Direct | Medium |
+| **ngrok tunnel** | None (outbound) | ngrok relay | Medium |
+| **VPN + SSH** | Yes (behind VPN) | VPN + direct | Low |
+
+For the highest security: prefer SSH over VPN rather than Remote Control, especially on sensitive environments.
+
+---
+
+*Version 1.2.0 | February 2026 | Part of [Claude Code Ultimate Guide](../README.md)*