docs(agents): add Remote Access section — remote.sh chokepoint + DNS-only

Establishes non-negotiable pattern for projects managing remote hosts:
all SSH through a remote.sh chokepoint (never direct ssh/scp), DNS names
only (never IP literals), and qemu-guest-agent visibility-only (never
execution). Adds corresponding DO NOT entries.

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Assisted-by: Crush:glm-5.2

AGENTS.md

@@ -164,6 +164,25 @@ docker run --rm --env-file ~/.creds/discourse.env \
 - **Secrets:** NEVER commit secrets. Credentials come from env vars / `.env` (gitignored). Use placeholders in `.env.example`.
 - **IAC testing:** test against the corresponding `sectestbed-` VM (snapshot to base state). `preprod-` VMs for vendor-upgrade testing. Do not require AWX as a prerequisite.
 
+## Remote Access (projects with remote hosts)
+
+**If this project manages remote hosts** (servers, VMs, network devices),
+these rules are NON-NEGOTIABLE:
+
+- **Ship a `remote.sh` chokepoint.** ALL SSH/SCP to any host MUST route
+  through a single chokepoint script (`tests/remote.sh` or equivalent).
+  NEVER call `ssh`/`scp` directly — the harness blocks raw ssh and the
+  command scanner rejects it. One script = one place to configure
+  hosts/users/keys, one place to audit.
+- **DNS names ONLY.** NEVER use IP address literals in any command, script,
+  or config. ALWAYS use DNS names. If a DNS name does not resolve, fix DNS
+  first — do not fall back to IP literals. This eliminates the per-session
+  discovery tax of finding the right IP for each host.
+- **If using qemu-guest-agent:** visibility only (`qm guest cmd <id> ping`,
+  `network-get-interfaces`). NEVER use `qm guest exec` or any wrapper as an
+  execution, access, or key-delivery channel. SSH is the only approved
+  remote access path.
+
 ## Key Commands
 
 At a terminal (Mode 1), use `make` or call scripts directly:
@@ -217,6 +236,9 @@ Bypass with `--no-verify` in genuine emergencies only.
 - Install language toolchains on the host.
 - Use `:latest` image tags or Docker's default container naming.
 - Author long-form docs in gitea — use Discourse.
+- Call `ssh`/`scp` directly — always route through the project's `remote.sh` chokepoint.
+- Use IP address literals for any host — always use DNS names.
+- Use `qm guest exec` or any guest-agent execution channel — SSH only.
 - Commit secrets.
 - Run destructive git operations without explicit instruction.
 - Declare the work "done" — the human decides that.