docs: define full-token Windows fixture provisioner

docs/implementation-plan.v1.md

@@ -830,11 +830,14 @@ Guest Control uses `rvboxtest`'s split-token, medium-integrity identity; its
 Administrators SID is deny-only. The reset snapshot contains no RVBox
 installation and the harness proves that `RVBoxClient` is absent immediately
 after every `prepare`. Do not bypass UAC or turn this active-session test user
-into an always-elevated account. Instead, provision a separate fixture-only
-full-token administrator, with its username and a mode-0600 host-side password
-file held outside the repository. `test-host install` uses that identity only
-to execute the staged real `rvbox.exe --install-service` path and proves it by
-polling SCM. It is not an RVBox product process, a service/broker, or a Task
+into an always-elevated account. Instead, enable the built-in Windows
+`Administrator` account only on this disposable fixture, retain its credential
+in a mode-0600 host-side password file, and preserve the normal Windows 10
+`FilterAdministratorToken=0` setting so Guest Control obtains a full high token.
+The harness verifies that token and fails closed if policy filters it; do not
+globally disable UAC or use a bypass. `test-host install` uses that identity
+only to execute the staged real `rvbox.exe --install-service` path and proves it
+by polling SCM. It is not an RVBox product process, a service/broker, or a Task
 Scheduler dependency, and it never enters the daemon's command-context choice.
 The normal active `rvboxtest` session remains the target for execution-role
 tests. The consent-prompt branch itself remains an interactive UAC test; an

docs/testing-vm.md

@@ -167,18 +167,23 @@ guest deletion.
 therefore launches it at medium integrity and it must never be used to create
 or modify machine-wide SCM state. The reset snapshot has no RVBox installation.
 
-To automate the real install path, provision one separate **fixture-only**
-full-token local administrator and retain its username/password solely in the
-Helium secret store. It must be a genuinely high-integrity Guest Control token;
-do not globally disable UAC or change `rvboxtest` into an always-elevated user.
-The normal harness receives it only through these environment variables:
+To automate the real install path, use the Windows built-in `Administrator`
+account as a separate **fixture-only** provisioning identity. Enable it only on
+this disposable VM, keep `FilterAdministratorToken=0` (the normal Windows 10
+default), and verify that Guest Control gives it a High Mandatory Level. This
+is the per-account exception that preserves UAC for `rvboxtest`; do **not**
+globally disable Admin Approval Mode or change `rvboxtest` into an
+always-elevated user. Store its username/password solely in the Helium secret
+store. The normal harness receives it only through these environment variables:
 
 ```sh
-export RVBOX_TEST_PROVISIONER_USER=FIXTURE_ONLY_FULL_ADMIN
+export RVBOX_TEST_PROVISIONER_USER=Administrator
 export RVBOX_TEST_PROVISIONER_PASSWORD_FILE=/home/cabbage/.local/share/rvbox-secrets/rvbox-win10-test-provisioner.password
 ```
 
-Both files remain mode `0600` on Helium and neither value is recorded in run
+If a policy or hardening configuration makes this account medium-integrity, the
+harness fails closed; do not replace it with a UAC-bypass mechanism. Both files
+remain mode `0600` on Helium and neither value is recorded in run
 reports or artifacts. `test-host install` first verifies that the reset guest
 has no `RVBoxClient`, checks the provisioner's High Mandatory Level, invokes
 the actual staged `rvbox.exe --install-service --config ...`, and polls SCM for

docs/testing.md

@@ -176,8 +176,10 @@ coverage.
 The clean baseline intentionally contains no RVBox service, tray registration,
 or RVBox state. Guest Control supplies `rvboxtest` with a filtered medium UAC
 token, so it cannot safely perform the first machine-wide install. The fixture
-therefore has a separate test-only full-token automation principal, whose
-username and mode-600 host-side password-file are provided only as
+therefore uses its separately enabled built-in `Administrator` account as a
+test-only full-token automation principal. Its `FilterAdministratorToken` must
+remain `0`, preserving UAC for `rvboxtest` rather than disabling it machine-wide.
+Its username and mode-600 host-side password-file are provided only as
 `RVBOX_TEST_PROVISIONER_USER` and `RVBOX_TEST_PROVISIONER_PASSWORD_FILE` for
 the `install`/machine-mutation actions. It is not an RVBox process, service,
 broker, or Task Scheduler dependency, and it is never used to choose a command