diff --git a/dsl/extdeps/bmc/types.dag b/dsl/extdeps/bmc/types.dag
index eeab55ad414..38cf5af5507 100644
--- a/dsl/extdeps/bmc/types.dag
+++ b/dsl/extdeps/bmc/types.dag
@@ -122,6 +122,10 @@ type RedfishPrivilege =
   | PrivilegeConfigureComponents
   | PrivilegeConfigureSelf
 
+type RedfishVirtualMediaSupport =
+    VirtualMediaSupported
+  | VirtualMediaUnsupported
+
 fn redfish_boot_target_wire(t: RedfishBootSourceOverrideTarget) -> NonEmptyStr {
   match t {
     BootTargetNone => "None"
diff --git a/dsl/extdeps/boards/asrock_rack.dag b/dsl/extdeps/boards/asrock_rack.dag
index c2bd58f76f1..a2614987315 100644
--- a/dsl/extdeps/boards/asrock_rack.dag
+++ b/dsl/extdeps/boards/asrock_rack.dag
@@ -7,6 +7,7 @@ import std.baseboard {
 import std.bmc { OpenBmc }
 import std.types { NonEmptyStr }
 
+import extdeps.bmc.types { RedfishVirtualMediaSupport, VirtualMediaUnsupported }
 import extdeps.external_authority { ExternalAuthority }
 import extdeps.uri { Uri, Https }
 
@@ -25,3 +26,5 @@ data asrock_altrad8ud_1l2t_catalog: BaseboardCatalogRow = BaseboardCatalogRow {
 
 data asrock_altrad8ud_redfish_system_id: NonEmptyStr = "system"
 data asrock_altrad8ud_redfish_chassis_id: NonEmptyStr = "ALTRAD8UD_1L2T"
+
+data asrock_altrad8ud_virtual_media_support: RedfishVirtualMediaSupport = VirtualMediaUnsupported
diff --git a/dsl/extdeps/os/ubuntu_autoinstall.dag b/dsl/extdeps/os/ubuntu_autoinstall.dag
new file mode 100644
index 00000000000..29c301021d2
--- /dev/null
+++ b/dsl/extdeps/os/ubuntu_autoinstall.dag
@@ -0,0 +1,25 @@
+module extdeps.os.ubuntu_autoinstall
+
+import std.logic { Bool }
+import std.types { Int }
+import std.os.types { UbuntuDistribution }
+import extdeps.uri { Uri, Https }
+import extdeps.external_authority { ExternalAuthority }
+
+data extdeps_external_authority_anchor: ExternalAuthority = ExternalAuthority {
+  uri: Uri {
+    scheme: Https
+    locator: "canonical-subiquity.readthedocs-hosted.com/en/latest/reference/autoinstall-reference.html"
+  }
+}
+
+type AutoinstallDeliveryMethod =
+    NoCloudNet { seed_url: Uri }
+  | NoCloudLocal
+
+type UbuntuAutoinstallPayload {
+  autoinstall_version: Int
+  delivery: AutoinstallDeliveryMethod
+  fully_automated: Bool
+  target_distribution: UbuntuDistribution
+}
diff --git a/dsl/extdeps/provisioning/network_boot.dag b/dsl/extdeps/provisioning/network_boot.dag
new file mode 100644
index 00000000000..da2b3d27c1e
--- /dev/null
+++ b/dsl/extdeps/provisioning/network_boot.dag
@@ -0,0 +1,57 @@
+module extdeps.provisioning.network_boot
+
+import std.types { NonEmptyStr }
+import extdeps.toolchain.types {
+  Architecture,
+  X86_64,
+  X86,
+  Aarch64,
+  Arm,
+  Armv7,
+  Mips,
+  Mipsel,
+  Mips64,
+  Mips64el,
+  Riscv64,
+  Wasm32,
+}
+import extdeps.uri { Uri, Https }
+import extdeps.external_authority { ExternalAuthority }
+
+data extdeps_external_authority_anchor: ExternalAuthority = ExternalAuthority {
+  uri: Uri {
+    scheme: Https
+    locator: "uefi.org/specs/UEFI/2.10/24_Network_Protocols_UDP_and_MTFTP.html"
+  }
+}
+
+type ClientNetworkBootMode =
+    LegacyBiosPxe { tftp_root: Uri }
+  | UefiPxe { tftp_root: Uri }
+  | UefiHttpBoot
+
+type DhcpBootDirection =
+    NativeDhcpBootOptions
+  | ProxyDhcp
+
+fn network_uefi_bootloader_artifact(arch: Architecture) -> NonEmptyStr? {
+  match arch {
+    Aarch64 => Present { value: "grubnetaa64.efi" }
+    X86_64 => Present { value: "grubnetx64.efi" }
+    X86 => Absent
+    Arm => Absent
+    Armv7 => Absent
+    Mips => Absent
+    Mipsel => Absent
+    Mips64 => Absent
+    Mips64el => Absent
+    Riscv64 => Absent
+    Wasm32 => Absent
+  }
+}
+
+type NetworkBootChain {
+  boot_mode: ClientNetworkBootMode
+  dhcp_direction: DhcpBootDirection
+  image_http_root: Uri
+}
diff --git a/dsl/gunbc/os_install.dag b/dsl/gunbc/os_install.dag
new file mode 100644
index 00000000000..fc3ca970abd
--- /dev/null
+++ b/dsl/gunbc/os_install.dag
@@ -0,0 +1,92 @@
+module gunbc.os_install
+
+import std.logic { Bool }
+import std.os.types { OperatingSystemProduct, UbuntuOs, NobleNumbat2404Lts }
+import extdeps.toolchain.types { Architecture, Aarch64 }
+import extdeps.uri { Uri, Https }
+import extdeps.provisioning.network_boot {
+  NetworkBootChain,
+  UefiHttpBoot,
+  DhcpBootDirection,
+  NativeDhcpBootOptions,
+  ProxyDhcp,
+}
+import extdeps.os.ubuntu_autoinstall {
+  UbuntuAutoinstallPayload,
+  NoCloudNet,
+}
+import extdeps.bmc.types {
+  RedfishBootSourceOverrideTarget,
+  BootTargetPxe,
+  RedfishBootSourceOverrideEnabled,
+  BootOverrideOnce,
+  RedfishResetType,
+  ResetForceRestart,
+}
+
+type NetworkBootDelivery {
+  chain: NetworkBootChain
+  autoinstall: UbuntuAutoinstallPayload
+}
+
+type LanInstallInfraSurvey {
+  existing_dhcp_configurable: Bool
+  dedicated_install_server_present: Bool
+}
+
+fn survey_implied_dhcp_direction(survey: LanInstallInfraSurvey) -> DhcpBootDirection {
+  if survey.existing_dhcp_configurable {
+    NativeDhcpBootOptions
+  } else {
+    ProxyDhcp
+  }
+}
+
+type Srv3OsInstallPlan {
+  os_target: OperatingSystemProduct
+  host_architecture: Architecture
+  lan_survey: LanInstallInfraSurvey
+  network_boot_delivery: NetworkBootDelivery
+  bmc_boot_target: RedfishBootSourceOverrideTarget
+  bmc_boot_enabled: RedfishBootSourceOverrideEnabled
+  post_stage_reset: RedfishResetType
+}
+
+data srv3_lan_install_survey: LanInstallInfraSurvey = LanInstallInfraSurvey {
+  existing_dhcp_configurable: false,
+  dedicated_install_server_present: false,
+}
+
+data srv3_network_boot_chain: NetworkBootChain = NetworkBootChain {
+  boot_mode: UefiHttpBoot,
+  dhcp_direction: survey_implied_dhcp_direction(survey: srv3_lan_install_survey),
+  image_http_root: Uri {
+    scheme: Https,
+    locator: "install.srv3.lan/ubuntu-24.04/",
+  },
+}
+
+data srv3_ubuntu_autoinstall: UbuntuAutoinstallPayload = UbuntuAutoinstallPayload {
+  autoinstall_version: 1,
+  delivery: NoCloudNet {
+    seed_url: Uri {
+      scheme: Https,
+      locator: "install.srv3.lan/ubuntu-24.04/autoinstall/",
+    },
+  },
+  fully_automated: true,
+  target_distribution: NobleNumbat2404Lts,
+}
+
+data srv3_os_install_plan: Srv3OsInstallPlan = Srv3OsInstallPlan {
+  os_target: UbuntuOs { distro: NobleNumbat2404Lts },
+  host_architecture: Aarch64,
+  lan_survey: srv3_lan_install_survey,
+  network_boot_delivery: NetworkBootDelivery {
+    chain: srv3_network_boot_chain,
+    autoinstall: srv3_ubuntu_autoinstall,
+  },
+  bmc_boot_target: BootTargetPxe,
+  bmc_boot_enabled: BootOverrideOnce,
+  post_stage_reset: ResetForceRestart,
+}
diff --git a/dsl/test/claim/srv3_os_install_witness_test.dag b/dsl/test/claim/srv3_os_install_witness_test.dag
new file mode 100644
index 00000000000..607649a23b7
--- /dev/null
+++ b/dsl/test/claim/srv3_os_install_witness_test.dag
@@ -0,0 +1,97 @@
+module test.claim.srv3_os_install
+
+import std.logic { Bool }
+import std.os.types { UbuntuOs, WindowsOs, MacosOs, NobleNumbat2404Lts }
+import extdeps.toolchain.types { X86_64, Riscv64 }
+import extdeps.provisioning.network_boot {
+  network_uefi_bootloader_artifact,
+  NativeDhcpBootOptions,
+  ProxyDhcp,
+  UefiHttpBoot,
+  LegacyBiosPxe,
+  UefiPxe,
+}
+import extdeps.os.ubuntu_autoinstall {
+  NoCloudNet,
+  NoCloudLocal,
+}
+import gunbc.os_install {
+  LanInstallInfraSurvey,
+  survey_implied_dhcp_direction,
+  srv3_network_boot_chain,
+  srv3_os_install_plan,
+}
+import extdeps.bmc.types {
+  redfish_boot_target_wire,
+  redfish_boot_override_enabled_wire,
+  VirtualMediaSupported,
+  VirtualMediaUnsupported,
+}
+import extdeps.boards.asrock_rack {
+  asrock_altrad8ud_virtual_media_support,
+}
+
+test fn srv3_bootloader_artifact_is_arch_grounded() -> Bool {
+  match network_uefi_bootloader_artifact(arch: srv3_os_install_plan.host_architecture) {
+    Present { value: a } => a == "grubnetaa64.efi"
+    Absent => false
+  }
+    && match network_uefi_bootloader_artifact(arch: X86_64) {
+      Present { value: x } => x == "grubnetx64.efi"
+      Absent => false
+    }
+    && match network_uefi_bootloader_artifact(arch: Riscv64) {
+      Present { value: _ } => false
+      Absent => true
+    }
+}
+
+test fn srv3_chain_is_uefi_http_boot() -> Bool {
+  match srv3_network_boot_chain.boot_mode {
+    UefiHttpBoot => true
+    LegacyBiosPxe { tftp_root: _ } => false
+    UefiPxe { tftp_root: _ } => false
+  }
+}
+
+test fn srv3_survey_forces_proxy_dhcp() -> Bool {
+  match srv3_network_boot_chain.dhcp_direction {
+    ProxyDhcp => true
+    NativeDhcpBootOptions => false
+  }
+    && match survey_implied_dhcp_direction(
+      survey: LanInstallInfraSurvey {
+        existing_dhcp_configurable: true,
+        dedicated_install_server_present: false,
+      }
+    ) {
+      ProxyDhcp => false
+      NativeDhcpBootOptions => true
+    }
+}
+
+test fn srv3_board_has_no_virtual_media() -> Bool {
+  match asrock_altrad8ud_virtual_media_support {
+    VirtualMediaSupported => false
+    VirtualMediaUnsupported => true
+  }
+}
+
+test fn srv3_plan_targets_ubuntu_2404_aarch64_pxe_once() -> Bool {
+  match srv3_os_install_plan.os_target {
+    UbuntuOs { distro: d } =>
+      match d {
+        NobleNumbat2404Lts => true
+      }
+    WindowsOs { distro: _ } => false
+    MacosOs { distro: _ } => false
+  }
+    && redfish_boot_target_wire(t: srv3_os_install_plan.bmc_boot_target) == "Pxe"
+    && redfish_boot_override_enabled_wire(e: srv3_os_install_plan.bmc_boot_enabled) == "Once"
+    && srv3_os_install_plan.network_boot_delivery.autoinstall.fully_automated
+    && srv3_os_install_plan.network_boot_delivery.autoinstall.autoinstall_version == 1
+    && match srv3_os_install_plan.network_boot_delivery.autoinstall.delivery {
+      NoCloudNet { seed_url: _ } => true
+      NoCloudLocal => false
+    }
+}