system: validate UEFI installer ISO boot path

docs/reports/phase18-installer-iso-freebsd.md

@@ -52,12 +52,16 @@ Instead it uses a small UEFI El Torito boot image plus an in-memory installer ro
 3. the ISO root also contains `/boot/root.img`
 4. `loader.conf` on the ISO is augmented with:
    - `mdroot_load="YES"`
-   - `mdroot_type="md_image"`
+   - `mdroot_type="mfs_root"`
    - `mdroot_name="/boot/root.img"`
-   - `rootdev="ufs:/dev/md0"`
    - `vfs.root.mountfrom="ufs:/dev/md0"`
    - `vfs.root.mountfrom.options="rw"`
 
+A practical loader detail surfaced during validation:
+
+- setting `rootdev` or `currdev` to `md0:` in the ISO loader path is wrong for this loader configuration and caused an early EFI-loader crash before kernel handoff
+- the reliable ISO path is to let loader keep its current device on the CD media, preload `/boot/root.img`, and pass only `vfs.root.mountfrom=ufs:/dev/md0`
+
 This preserves the existing Fruix installer environment semantics while avoiding the need to make the whole installer operate directly from a read-only ISO root.
 
 ### Installer root image contents
@@ -66,7 +70,7 @@ This preserves the existing Fruix installer environment semantics while avoiding
 
 - installer closure
 - target closure
-- target store closure
+- target runtime store closure needed for installation/boot
 - staged target rootfs under `/var/lib/fruix/installer/target-rootfs`
 - installer plan and state files under `/var/lib/fruix/installer`
 - installer helper scripts:
@@ -86,7 +90,7 @@ While exercising the refactored split modules, two issues surfaced and were fixe
    - this constant was accidentally omitted when `modules/fruix/system/freebsd.scm` was split
    - the missing definition was restored in `modules/fruix/system/freebsd/build.scm`
 
-## Current validation status
+## Validation
 
 ### Completed smoke validation
 
@@ -119,21 +123,83 @@ installer_closure_path=/tmp/...-fruix-system-fruix-freebsd-installer
 target_closure_path=/tmp/...-fruix-system-fruix-freebsd
 ```
 
-### Validation harness added
+### End-to-end harness validation
 
 Added:
 
 - `tests/system/run-phase18-installer-iso.sh`
 
-This harness is intended to validate the full Phase 18.3 flow:
+This harness validates the full Phase 18.3 flow:
 
 1. build installer ISO
 2. boot it under QEMU/UEFI/TCG
-3. install onto a second disk from inside the booted ISO environment
+3. install onto a target disk from inside the booted ISO environment
 4. boot the installed target
 
-## Status
+Passing validation:
 
-Phase 18.3 implementation is now in place, with successful build-smoke validation and a dedicated end-to-end harness added.
+- `PASS phase18-installer-iso`
 
-The remaining step is full end-to-end boot/install validation of the ISO path under QEMU/UEFI/TCG and, if practical, the broader validated virtualization path.
+Validated result summary:
+
+```text
+installer_iso_store_path=/frx/store/...-fruix-installer-iso-fruix-freebsd-installer
+installer_iso_image=/frx/store/...-fruix-installer-iso-fruix-freebsd-installer/installer.iso
+installer_boot_efi_image=/frx/store/...-fruix-installer-iso-fruix-freebsd-installer/efiboot.img
+installer_root_image=/frx/store/...-fruix-installer-iso-fruix-freebsd-installer/root.img
+install_target_device=/dev/vtbd0
+freebsd_source_kind=git
+freebsd_source_ref=stable/15
+freebsd_source_commit=332708a606f6bf0841c1d4a74c0d067f5640fe89
+materialized_source_store=/frx/store/459499e0eb29f4c73ad455060dd2502d21fb56f205c0a676831cf723b3a0c378-freebsd-source-stable15-installer-iso-target-source
+installer_state=done
+installer_sshd_status=running
+target_esp_fstype=msdosfs
+target_root_fstype=ufs
+target_shepherd_status=running
+target_sshd_status=running
+installer_iso_boot=ok
+installer_iso_install=ok
+installed_target_boot=ok
+```
+
+Notable ISO-specific validation detail:
+
+- unlike the disk-image-style installer environment from Phase 18.2, the ISO boots from `cd0`, so the target virtio disk appears as:
+  - `/dev/vtbd0`
+- the earlier installer-environment default:
+  - `/dev/vtbd1`
+  remains correct for the disk-image installer, but not for the ISO path
+
+The harness verified all of the following:
+
+1. `fruix system installer-iso` produces a bootable ISO artifact in `/frx/store`
+2. the ISO boots successfully under QEMU/UEFI/TCG
+3. the booted installer ISO environment becomes reachable over SSH
+4. `/run/current-system` inside the installer ISO points at the installer closure
+5. the installer rc.d job reaches:
+   - `state=done`
+6. the installer log records:
+   - `fruix-installer:done`
+7. the installed target disk contains:
+   - GPT partitioning
+   - EFI filesystem: `msdosfs`
+   - root filesystem: `ufs`
+   - `EFI/BOOT/BOOTX64.EFI`
+   - `/var/lib/fruix/install.scm`
+8. the installed target then boots successfully as its own Fruix system under QEMU/UEFI/TCG
+9. after target boot:
+   - `/run/current-system` points at the target closure
+   - shepherd is running
+   - `sshd` is running
+   - activation completed successfully
+
+## Result
+
+Phase 18.3 is complete.
+
+Fruix now has a validated bootable UEFI installer ISO on FreeBSD that can:
+
+- boot into a Fruix-managed installer environment from ISO media
+- perform the non-interactive installation flow onto a target disk
+- and boot the installed target successfully