diff --git a/docs/concepts/payload.md b/docs/concepts/payload.md
index 757b71a..c485524 100644
--- a/docs/concepts/payload.md
+++ b/docs/concepts/payload.md
@@ -103,6 +103,13 @@ An `--owner-trust-cache` bundle is copied without the `[payload] trust_cache_sha
 
 ## Data ramdisk
 
+When the selected kernel configuration enables `CONFIG_XNU_OWNER_DATA_MOUNT`,
+the payload requires `--data-ramdisk FILE` or `[build] data_ramdisk` in the local
+build configuration. Without a generated `.config`, this check reads the
+selected device defconfig. A persistent overlay still needs its original seed
+to publish the Data volume; changing the seed is not a way to resume old Data.
+Missing seeds stop packaging before the payload is written.
+
 A Data seed can be delivered in two forms:
 
 | Form | ADT placeholder | Behavior |
diff --git a/docs/drivers/ath12k-wifi.md b/docs/drivers/ath12k-wifi.md
index 3bbfb6e..3c781d4 100644
--- a/docs/drivers/ath12k-wifi.md
+++ b/docs/drivers/ath12k-wifi.md
@@ -28,6 +28,22 @@ Status: joins WPA2-Personal, gets DHCP, Safari loads pages. Throughput is low.
 | `sheng-wifi=5` | Start Wi-Fi. Without it the module never runs. |
 | `sheng-wifi-aj=0` | No join at boot; Settings joins. |
 
+### iPadOS 27 service startup
+
+The sheng board DTS exports WCN7850 as `/arm-io/wlan` using
+`unixnu,adt-name = "wlan"`. The stock 24A446 `com.apple.wifid` job checks
+`_LimitLoadToDeviceTree` before launchd loads it. Without a matching node,
+the kernel's `join.txt` path can still connect and exchange packets while
+Settings shows an empty Wi-Fi page and cannot enable the switch.
+`/chosen/mac-address-wifi0` and the IOService network objects do not satisfy
+this device-tree condition.
+
+The 27 payload defaults include `sheng-wifi=5`. After changing the DTS,
+rebuild the payload and boot image, then inspect the ADT inside the image.
+Host checks confirm the node satisfies the startup condition; starting
+wifid, enabling the Settings switch and scanning still require a device
+test. Remove `sheng-autoreset` from a manual test image's boot arguments.
+
 ### Facts
 
 - Each of the six PMU rails needs RPMh mode, voltage and enable requests. Without the mode request two rails stay off and the link never trains.
diff --git a/docs/drivers/xnu-prelink.md b/docs/drivers/xnu-prelink.md
index 1409f45..5e73804 100644
--- a/docs/drivers/xnu-prelink.md
+++ b/docs/drivers/xnu-prelink.md
@@ -19,12 +19,44 @@ matching code signature before reusing a map.
 comparison. It transfers unambiguous names from unique code matches and resolves
 those names in the actual native kernel. The map records the reference hash.
 
+The sheng iPadOS 27 build runs `build-fileset-release-reference.py --tree . --lto`
+before prelinking. Keep LTO enabled for this comparison: the non-LTO reference
+loses matches needed by original kexts, including corecrypto's startup call to
+`kprintf`. With `--allow-missing`, such a call reaches `unixnu_fileset_unmapped`
+at runtime even though packaging succeeds.
+
+The reference builder records its mode, source, SDK, archive, compiler and
+version inputs and verifies the output digest before reusing it. Unrecorded
+references are rebuilt. Different inputs use separate build directories;
+LTO export inspection reads the generated LTO object and non-LTO file list.
+After a reference change, regenerate the map, kernel, payload and boot image,
+and inspect the unresolved-target report before hardware testing.
+
+The 24A446 fixture preserves 23 import identities recovered from the retained
+RELEASE-LTO map and cross-checked against its boot image, plus the observed
+corecrypto `kprintf` import. Their original function digests and recovery
+provenance are recorded; the current native targets are resolved by symbol.
+The fixture also identifies 13 previously missing vnode operation descriptors by
+`vdesc_name`, four metaclass pointer slots by their chained targets, and the
+`gIODTPHandleKey` and `audio_active` globals by their source consumers. Unbound
+vnode descriptors can make APFS registration read a zone field as an operation
+index in `vfs_fsadd`; they must resolve to the native descriptors initialized by
+VFS, not preserve old collection data addresses.
+
+
 The emitter places native segments within the collection's code, constant and
 data ranges, applies native split-segment records, rebuilds chained fixups and
 function starts, and recomputes corecrypto's code HMAC. The collection root uses
 the native link address. The ordinary prelink `--slide` value does not apply to
 filesets. The native input executable is unchanged.
 
+Native adapters to retained kext functions declare fixed targets as `N_ABS`
+`<stub>.original` symbols and use `BTI c; B` stubs. These branches lack linker
+split-segment records, so the emitter recomputes them after placement and checks
+every destination against retained executable ranges. The report records each
+binding in `native_original_branches`. Builders must not pre-subtract a cached
+native slide. Absolute data pointers in GOT entries keep their fixed values.
+
 Missing mappings stop emission by default. `--allow-missing` produces an
 experimental image and the JSON report lists every unresolved target by kext.
 An image that passes structural checks still requires complete mappings and
@@ -43,3 +75,9 @@ The catalog records implementation scope, hardware and OS requirements, board de
 ```
 
 [Component catalog](/reference/components)
+
+The 24A446 packaging profile additionally checks a regression policy against the
+original (unslid) imported targets. New unresolved data or stubbed calls fail
+before replacing the last kernel candidate. This caught two lost order-based
+matches during a full rebuild: `IOCircularDataQueueCopyLatest` and `get_aiotask`;
+the reviewed fixture now identifies both by original digest and native symbol.
diff --git a/docs/porting/packaging.md b/docs/porting/packaging.md
index 6cb3e79..04b19d5 100644
--- a/docs/porting/packaging.md
+++ b/docs/porting/packaging.md
@@ -124,3 +124,43 @@ Booting the artifacts is a separate step with its own record.
 4. Record the run in the `packaging` area of `porting.toml`.
 
 [Build and boot](/building), [Device repository](/porting/device-repository)
+
+## Runtime inputs for sheng iPadOS 27
+
+The payload's `runtime` table enables preparation before kernel compilation.
+Apple static/System/App trust modules come from the selected IPSW unchanged. Turnip,
+AdrenoMetal and the board audio HAL are built from source; their CDHashes are
+appended as a separate owner trust module. Wallpaper overlays come from the
+read-only OS image. The official Xiaomi fastboot archive still supplies the
+firmware inputs through the board preflight scripts.
+
+An existing installation must reuse its original `data.dbr` with
+`--data-ramdisk FILE`. GPU and audio updates travel in the addon and do not edit
+that seed. The runtime step checks its APFS volume UUID against the generated
+kernel configuration and records the input SHA-256 values in the package manifest.
+A payload-only build refuses a different Data UUID and asks for a kernel rebuild.
+
+For a **first installation**, `scripts/package.sh --os 27 --init-data` creates an
+APFS seed from the IPSW's initial `private/var`, uses the board's `data_gib` and
+Setup preferences, and binds the new UUID into the kernel configuration. This
+writes host build files only; it does not erase or flash a device. Keep the seed
+at `out/sheng/ipados-27.0.1-24A446/sheng_ipados27/runtime/data.dbr` for every later
+build of that installation. Its content identity, not just its UUID, identifies
+the persistent Data store. Regenerating it cannot preserve an older installation.
+
+The package workflow restores this seed from an installation cache, or accepts
+an original seed URL with a required SHA-256. A missing cache stops the build
+unless `init_data` is explicitly selected. The workflow uploads a separate seed
+backup with one-day retention. Download and retain it: Actions caches are not a
+permanent backup. The current device's seed is not supplied by either firmware
+archive. Automatic runtime generation currently targets the iPadOS 27 profile.
+
+`--gpu-addon FILE` and its matching `--owner-trust-cache FILE` remain available
+for reproducing an existing image. Omit both to compile the addon and generate
+its trust bundle. These generated binaries and installation seeds are not Git
+inputs.
+
+For the 24A446 fileset, `regression_policy` bounds the unresolved references by
+original kernel address and importing component. New gaps fail packaging even
+with `--allow-missing`; this check does not qualify the remaining experimental
+paths or replace a device boot test.
diff --git a/docs/zh/concepts/payload.md b/docs/zh/concepts/payload.md
index 7c282b4..b6bac22 100644
--- a/docs/zh/concepts/payload.md
+++ b/docs/zh/concepts/payload.md
@@ -41,6 +41,11 @@ initrd = "Payloads/scratch-data.img"
 args = "-v serial=3"
 ```
 
+所选内核配置启用了 `CONFIG_XNU_OWNER_DATA_MOUNT` 时，必须通过
+`--data-ramdisk FILE` 或本地构建配置的 `[build] data_ramdisk` 提供种子。
+没有生成 `.config` 时检查所选设备 defconfig。持久化覆盖层也需要原始种子来
+发布 Data 卷；更换种子不能恢复旧 Data。缺少种子会在写负载前报错。
+
 提供 Data 种子时存在 `initrd`。`args` 是 `[payload] kernel_args` 和 `--kernel-arg` 合并后的命令行。
 
 ## ADT sidecar
diff --git a/docs/zh/drivers/ath12k-wifi.md b/docs/zh/drivers/ath12k-wifi.md
index be53143..6e2e485 100644
--- a/docs/zh/drivers/ath12k-wifi.md
+++ b/docs/zh/drivers/ath12k-wifi.md
@@ -26,6 +26,20 @@ Ath12kWifi 在自己的兼容层（`shim/`）上编译 Linux 的 ath12k、MHI 
 | `sheng-wifi=5` | 启动 Wi-Fi。没有它模块不会运行。 |
 | `sheng-wifi-aj=0` | 启动时不加入网络，由设置加入。 |
 
+### iPadOS 27 服务启动
+
+sheng 的板级 DTS 通过 `unixnu,adt-name = "wlan"` 将 WCN7850 导出为
+`/arm-io/wlan`。24A446 原生 `com.apple.wifid` 任务带有
+`_LimitLoadToDeviceTree` 条件，launchd 加载前会检查。缺少匹配节点时，
+内核的 `join.txt` 路径仍能连接并收发数据，但设置中的 Wi-Fi 页面为空，
+开关无法打开。`/chosen/mac-address-wifi0` 和 IOService 网络对象不能满足
+这个设备树条件。
+
+27 的默认 payload 参数包含 `sheng-wifi=5`。修改 DTS 后需要重新生成
+payload 和 boot 镜像，并检查镜像内的 ADT。主机检查确认节点满足启动条件；
+wifid 启动、设置开关和扫描功能仍需上机验证。手动测试镜像的启动参数应移除
+`sheng-autoreset`。
+
 ### 事实
 
 - 六条 PMU 电源轨各需要 RPMh 的模式、电压和使能请求。缺少模式请求时有两条保持关闭，链路无法训练。
diff --git a/docs/zh/drivers/xnu-prelink.md b/docs/zh/drivers/xnu-prelink.md
index dcfbd75..874ffc2 100644
--- a/docs/zh/drivers/xnu-prelink.md
+++ b/docs/zh/drivers/xnu-prelink.md
@@ -5,6 +5,27 @@
 `--fileset-reference FILE` 可以提供带符号的对照内核。唯一的代码匹配可提供符号名，
 最终地址仍从实际编译的原生内核获取。映射记录中会保存对照文件的哈希。
 
+sheng 的 iPadOS 27 构建在预链接前运行
+`build-fileset-release-reference.py --tree . --lto`。该对照内核需要启用
+LTO；非 LTO 对照会丢失原生 kext 所需的匹配，包括 corecrypto 启动时对
+`kprintf` 的调用。启用 `--allow-missing` 时，打包可以成功，但该调用会在
+运行时进入 `unixnu_fileset_unmapped` 并触发 panic。
+
+对照内核构建脚本记录模式、源码、SDK、归档库、编译器和版本输入，复用前还
+会核对输出哈希。没有记录的旧产物会重建；输入改变时使用独立构建目录。
+LTO 模式从生成的 LTO 对象和非 LTO 文件列表检查导出符号。对照内核改变后，
+需要重新生成映射、内核、payload 和 boot 镜像，并在上机前检查未解析目标报告。
+
+24A446 的符号记录保留了从旧 RELEASE-LTO 映射恢复、并与对应启动镜像交叉
+核对的 23 个导入函数身份，以及此次定位的 corecrypto `kprintf` 导入。
+记录包含原始函数字节哈希和恢复依据；当前原生内核的目标地址仍按符号重新解析。
+
+固定记录还按 `vdesc_name` 识别 13 个此前缺失的 vnode 操作描述符，按链式
+指针目标识别 4 个 metaclass 指针槽，并通过源码调用方识别 `gIODTPHandleKey`
+和 `audio_active`。APFS 注册时会读取这些描述符的操作下标；保留旧地址可能
+把 zone 数据当成下标，导致 `vfs_fsadd` 越界。必须绑定到由新内核 VFS 初始化
+的描述符。
+
 对于 arm64e fileset 内核集合，`emit_prelink.py` 会选择 fileset 路径并生成
 函数和数据映射。`--fileset-map FILE` 可以指定已有映射，输入哈希和匹配器版本
 必须一致。输出保留所选根组件及其全部依赖。
@@ -14,6 +35,12 @@
 HMAC。集合根头使用原生内核的链接地址，普通预链接的 `--slide` 不用于 fileset。
 原生内核输入文件保持不变。
 
+原生适配器通过 `BTI c; B` 跳板调用保留的 kext 函数，固定目标由 `N_ABS`
+符号 `<stub>.original` 声明。这类跳转没有链接器分段重定位记录，因此输出工具
+在布局完成后重新计算跳转，并核验目标位于保留组件的可执行范围内。报告中的
+`native_original_branches` 记录每条绑定。构建脚本不得预先减去缓存的原生内核
+位移；GOT 中的绝对数据指针保持固定值。
+
 默认遇到缺失映射就停止。`--allow-missing` 可以生成实验映像，JSON 报告按
 kext 列出所有未解析目标。结构验证通过后，仍需要补全映射并进行硬件验证，
 才能确认启动兼容性。
@@ -39,3 +66,8 @@ XnuPrelink 将构建的 XNU 内核绑定到所选原始 kext，并写出预链
 ```
 
 [组件目录](/zh/reference/components)
+
+24A446 打包配置还会按原始、未滑动的导入地址检查回归清单。新增未解析数据或
+stub 调用会在替换上次内核产物前报错。完整重编曾丢失两个依赖顺序的匹配：
+`IOCircularDataQueueCopyLatest` 和 `get_aiotask`；现在已根据源码和反汇编，
+用原函数摘要及 native 符号固定其身份。
diff --git a/docs/zh/porting/packaging.md b/docs/zh/porting/packaging.md
index b4b43f2..de50494 100644
--- a/docs/zh/porting/packaging.md
+++ b/docs/zh/porting/packaging.md
@@ -106,3 +106,32 @@ remove = [ ... ]
 4. 把运行记录到 `porting.toml` 的 `packaging` 区域。
 
 [构建与启动](/zh/building)、[设备仓库](/zh/porting/device-repository)
+
+## sheng iPadOS 27 运行输入
+
+`payload.runtime` 在编译内核前准备运行输入。Apple 静态、System 和 App 信任模块从所选
+IPSW 原样提取；Turnip、AdrenoMetal 和设备音频 HAL 从源码编译，其 CDHash 写入
+单独的 owner 信任模块。壁纸覆盖文件从只读 OS 镜像生成。小米官方 fastboot 固件
+继续由设备 preflight 脚本下载、校验和提取。
+
+保留现有安装的数据时，必须通过 `--data-ramdisk FILE` 复用原来的 `data.dbr`。
+GPU 和音频更新放在 addon 中，不修改 seed。构建会检查 APFS 卷 UUID，将它绑定到
+本次生成的内核配置，并把输入 SHA-256 写入打包清单。只打包 payload 时，若 UUID
+与内核配置不同则报错，要求重新编译内核。
+
+**首次安装**可用 `scripts/package.sh --os 27 --init-data`，从 IPSW 的初始
+`private/var` 生成 APFS seed，采用设备配置的 `data_gib` 和 Setup 偏好，并把新
+UUID 写入内核配置。该命令只写本机构建文件，不擦除或刷写设备。此后应一直保留
+`out/sheng/ipados-27.0.1-24A446/sheng_ipados27/runtime/data.dbr`。
+持久化 Data 绑定的是 seed 的内容身份，仅保留 UUID 或从同一 IPSW 重做都不能替代原文件。
+
+Actions 会恢复安装对应的 seed 缓存，也支持原 seed 的下载 URL 加必填 SHA-256。
+缓存丢失时默认停止，只有明确选择 `init_data` 才会新建。工作流另提供保留一天的
+seed 备份下载；请自行长期保存，Actions 缓存不能作为永久备份。当前设备的原 seed
+无法从官方固件包恢复。自动生成运行输入目前只适用于 iPadOS 27。
+
+要复现已有镜像，可同时指定 `--gpu-addon FILE` 和配套的
+`--owner-trust-cache FILE`；省略二者则从源码构建。生成的二进制和 seed 不提交 Git。
+
+24A446 的 `regression_policy` 按原内核地址和导入组件限制未解析引用；即使启用
+`--allow-missing`，新增缺口也会使打包失败。这不代表剩余实验路径已验证，仍需上机启动测试。
diff --git a/kits/XnuPrelink b/kits/XnuPrelink
index b74ed7c..b1888c1 160000
--- a/kits/XnuPrelink
+++ b/kits/XnuPrelink
@@ -1 +1 @@
-Subproject commit b74ed7c74a07f0eb5f81089c660905ecc4cabb7f
+Subproject commit b1888c12456c46a2226d63c794465dfcee08d465
diff --git a/profiles/os/ipados-27.0.1-24A446/profile.toml b/profiles/os/ipados-27.0.1-24A446/profile.toml
index a0a2561..5e2c0c4 100644
--- a/profiles/os/ipados-27.0.1-24A446/profile.toml
+++ b/profiles/os/ipados-27.0.1-24A446/profile.toml
@@ -31,6 +31,7 @@
 "kernel" = "build/xnu/ios-obj/DEVELOPMENT_ARM64_BCM2837/mach.development.bcm2837.unstripped.noctf"
 "kernelcache_sha256" = "38e6d9fa5f789b8228f4617ef4c6d2a3fd8ab564abdc9b62920f1db53fc1780a"
 "slide" = "-0x1000000"
+regression_policy = "scripts/policies/ipados-27.0.1-24A446/prelink-regression.json"
 # The AMFI wrapper that calls _initializeAppleMobileFileIntegrity and returns 0; the kernel patch calls it early.
 "early_security_init" = "com.apple.driver.AppleMobileFileIntegrity=0xfffffe00092551ac"
 # Bring-up: match against the symbol-bearing RELEASE build of the same XNU source
diff --git a/scripts/build-adreno-metal-plugin.py b/scripts/build-adreno-metal-plugin.py
index 07b64e2..efa16b4 100644
--- a/scripts/build-adreno-metal-plugin.py
+++ b/scripts/build-adreno-metal-plugin.py
@@ -5,6 +5,7 @@ and the launchd probe daemon with its job plist (NativeAdrenoProbeDaemon.cpp).
 Output (ignored, never committed): build/adreno-metal-plugin/NativeAdrenoMetal.bundle with a 4 KiB-page ad-hoc signature, and
 trust.json with its CDHash. The bundle is staged into the Data seed by add-gpu-plugin-data.py and trusted through an extra
 owner trust module (make-owner-trust-bundle.py); neither changes the original trust modules, AMFI or any Apple signature."""
+import argparse
 import json
 import plistlib
 import re
@@ -15,7 +16,11 @@ from pathlib import Path
 
 ROOT = Path(__file__).resolve().parents[1]
 # --target ios27: the arm64e build for iPadOS 27 (24A446), whose render server is an arm64e process.
-IOS27 = sys.argv[1:] == ['--target', 'ios27']
+parser = argparse.ArgumentParser(description=__doc__)
+parser.add_argument('--target', choices=('ios', 'ios27'), default='ios')
+parser.add_argument('--no-replay', action='store_true', help='omit the optional host simulation capture used by diagnostic probes')
+args = parser.parse_args()
+IOS27 = args.target == 'ios27'
 OUT = ROOT / ('build/adreno-metal-plugin27' if IOS27 else 'build/adreno-metal-plugin')
 bundle = OUT / 'NativeAdrenoMetal.bundle'
 if OUT.exists():
@@ -30,7 +35,10 @@ if not TURNIP.is_file():
     raise SystemExit('Build Turnip first: python3 scripts/build-turnip-darwin.py --target ' + ('ios27' if IOS27 else 'ios'))
 subprocess.run(['python3', ROOT / 'scripts/gen-turnip-smoke-shaders.py'], check=True)
 # Turnip's first submission, recorded on the host, for the plugin's prefix replay (build/turnip-smoke/TurnipReplay.h).
-subprocess.run(['python3', ROOT / 'scripts/gen-turnip-replay.py'], check=True)
+if args.no_replay:
+    (ROOT / 'build/turnip-smoke/TurnipReplay.h').unlink(missing_ok=True)
+else:
+    subprocess.run(['python3', ROOT / 'scripts/gen-turnip-replay.py'], check=True)
 BRIDGE_TARGET = 'ios27' if IOS27 else 'ios'
 subprocess.run(['python3', ROOT / 'scripts/build-adreno-metal-bridge.py', '--target', BRIDGE_TARGET], check=True)
 BRIDGE = ROOT / 'build/adreno-metal-bridge' / BRIDGE_TARGET / 'libadreno_metal_bridge.a'
diff --git a/scripts/build-adreno740-accelerator.py b/scripts/build-adreno740-accelerator.py
index 061101d..f1f64be 100644
--- a/scripts/build-adreno740-accelerator.py
+++ b/scripts/build-adreno740-accelerator.py
@@ -92,11 +92,9 @@ sdk = run(['xcrun', '--sdk', 'iphoneos', '--show-sdk-path'], text=True).strip()
 binding_objects = [OUT / 'original-bindings.o']
 if FILESET:
     # As for the Legacy display (build-gop-legacy-display-27.py): original functions are reached through owned stubs in kernel text
-    # (signed and moved like native code) whose branch lands on the original after the collection slide, less the measured move of the
-    # native kernel (native-slide); the metaclass is data, reached through the GOT at its plain address.
+    # (signed and moved like native code). XnuPrelink retargets their branches after placing native text.
+    # The metaclass is data, reached through the GOT at its fixed collection address.
     slide = int(plan['collection_slide'], 16)
-    native_slide_file = ROOT / 'build/native-legacy-display/native-slide'
-    native_slide = int(native_slide_file.read_text(), 16) if native_slide_file.exists() else 0
     text, addresses = '.text\n.p2align 2\n', ''
     for n, a in sorted(bindings.items()):
         if n not in undefined:
@@ -104,7 +102,7 @@ if FILESET:
         if n.endswith('gMetaClassE'):
             addresses += f'.globl {n}\n.set {n}, {a + slide:#x}\n'
         else:
-            addresses += f'.globl {n}.original\n.set {n}.original, {(a + slide - native_slide) & ((1 << 64) - 1):#x}\n'
+            addresses += f'.globl {n}.original\n.set {n}.original, {a + slide:#x}\n'
             text += f'.globl {n}\n{n}:\n bti c\n b {n}.original\n'
     asm.write_text(text)
     (OUT / 'original-addresses.S').write_text(addresses)
diff --git a/scripts/build-boot-runtime.py b/scripts/build-boot-runtime.py
new file mode 100644
index 0000000..3bf7d84
--- /dev/null
+++ b/scripts/build-boot-runtime.py
@@ -0,0 +1,177 @@
+#!/usr/bin/env python3
+"""Build payload runtime inputs from a pinned IPSW and the selected sources.
+
+Invoked by unixnu.runtime with a JSON request; no device ID or private binary is
+stored in source control. Existing Data seeds are copied into no writable mount.
+"""
+import argparse
+import contextlib
+import json
+import os
+from pathlib import Path
+import plistlib
+import re
+import struct
+import subprocess
+import sys
+import tempfile
+import zlib
+
+ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(ROOT / 'scripts'))
+from mesa_patch_identity import validate_recorded_patches
+
+
+def run(*command, **kwargs):
+    subprocess.run([str(part) for part in command], check=True, **kwargs)
+
+
+def script(name, *args, **kwargs):
+    run(sys.executable, ROOT / 'scripts' / name, *args, **kwargs)
+
+
+@contextlib.contextmanager
+def os_mount(image, work):
+    # A developer may already have this exact OS mounted for inspection. Reuse
+    # only a read-only attachment, and leave its lifetime with its owner.
+    info = plistlib.loads(subprocess.check_output(['hdiutil', 'info', '-plist']))
+    for entry in info.get('images', []):
+        if Path(entry.get('image-path', '')).resolve() != Path(image).resolve():
+            continue
+        if entry.get('writeable', True):
+            raise SystemExit('The IPSW OS image is already attached writable; require an unchanged read-only input')
+        mounts = [Path(item['mount-point']) for item in entry.get('system-entities', [])
+                  if item.get('mount-point') and (Path(item['mount-point']) / 'sbin/launchd').is_file()]
+        if len(mounts) == 1:
+            yield mounts[0]
+            return
+    mount = work / 'os-mount'
+    mount.mkdir()
+    attached = plistlib.loads(subprocess.check_output(['hdiutil', 'attach', '-readonly', '-nobrowse',
+                                                       '-mountpoint', str(mount), '-plist', str(image)]))
+    device = attached['system-entities'][0]['dev-entry']
+    try:
+        yield mount
+    finally:
+        run('hdiutil', 'detach', device)
+
+
+def checkout(path, pin):
+    if not path.exists():
+        path.mkdir(parents=True)
+        run('git', 'init', '-q', path)
+        run('git', '-C', path, 'fetch', '--depth=1', pin.get('mirror', pin['repository']), pin['commit'])
+        run('git', '-C', path, 'checkout', '--detach', 'FETCH_HEAD')
+        return True
+    revision = subprocess.check_output(['git', '-C', str(path), 'rev-parse', 'HEAD'], text=True).strip()
+    if revision != pin['commit']:
+        raise SystemExit(f'{path}: source revision differs from its pin; preserve and inspect the checkout')
+    return False
+
+
+def build_plugin(target):
+    pins = json.loads((ROOT / 'scripts/data/adreno-compiler-inputs.json').read_text())
+    mesa = ROOT / '.cache/mesa-work'
+    fresh = checkout(mesa, pins['mesa'])
+    if fresh:
+        for patch in pins['patches']:
+            run('git', '-C', mesa, 'apply', ROOT / patch)
+    validate_recorded_patches(ROOT, mesa, pins)
+    translator = json.loads((ROOT / 'scripts/data/gpu-metal-vulkan-inputs.json').read_text())['translator']
+    checkout(ROOT / '.cache/gpu-reference/metal2vulkan', translator)
+    venv = ROOT / '.cache/mesa-venv'
+    if not (venv / 'bin/python').is_file():
+        run(sys.executable, '-m', 'venv', venv)
+    run(venv / 'bin/python', '-m', 'pip', 'install', '-r', ROOT / 'scripts/requirements-adreno-compiler.txt')
+    script('build-turnip-darwin.py', '--target', target)
+    # Replay is a diagnostic capture from a host GPU simulation, not a runtime
+    # dependency. Do not require unrelated test fixtures in a release build.
+    script('build-adreno-metal-plugin.py', '--target', target, '--no-replay')
+    return ROOT / 'build' / ('adreno-metal-plugin27' if target == 'ios27' else 'adreno-metal-plugin')
+
+
+def addon_hashes(path, work):
+    data = path.read_bytes()
+    if data[:8] != b'NGPUADD2' or len(data) < 24 or struct.unpack_from('<Q', data, 16)[0] != len(data):
+        raise SystemExit('invalid GPU addon')
+    at, executables = 24, []
+    for _ in range(struct.unpack_from('<I', data, 8)[0]):
+        length, mode, size, packed = struct.unpack_from('<IIQQ', data, at)
+        at += 24
+        name = data[at:at + length - 1].decode()
+        if not 1 < length <= 160 or name.startswith('/') or '..' in Path(name).parts:
+            raise SystemExit('invalid addon path')
+        at += (length + 7) & ~7
+        body = zlib.decompress(data[at:at + packed])
+        at += (packed + 7) & ~7
+        if len(body) != size:
+            raise SystemExit('invalid addon entry size')
+        output = work / name
+        output.parent.mkdir(parents=True, exist_ok=True)
+        output.write_bytes(body)
+        output.chmod(mode & 0o777)
+        if body[:4] in (b'\xcf\xfa\xed\xfe', b'\xca\xfe\xba\xbe'):
+            executables.append(output)
+    if at != len(data) or not executables:
+        raise SystemExit('invalid addon length or no executables')
+    hashes = []
+    for executable in executables:
+        run('codesign', '--verify', '--strict', executable)
+        detail = subprocess.run(['codesign', '--display', '--verbose=4', str(executable)],
+                                check=True, capture_output=True, text=True).stderr
+        match = re.search(r'^CDHash=([0-9a-f]{40})$', detail, re.M)
+        if not match:
+            raise SystemExit('no CDHash for ' + str(executable))
+        hashes.append(match[1])
+    return sorted(set(hashes))
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--request', type=Path, required=True)
+    request = json.loads(parser.parse_args().request.read_text())
+    out = Path(request['output'])
+    seed = Path(request['data_ramdisk'])
+    addon = Path(request['gpu_addon']) if request.get('gpu_addon') else None
+    trust = Path(request['trust_cache']) if request.get('trust_cache') else None
+    with tempfile.TemporaryDirectory(prefix='prepare-', dir=out) as td:
+        work = Path(td)
+        if not seed.is_file() or addon is None:
+            with os_mount(request['os_image'], work) as mount:
+                if not seed.is_file():
+                    if not request['init_data']:
+                        raise SystemExit('refuse to generate Data without --init-data')
+                    script('make-data-seed.py', mount, seed, '--gib', str(request['data_gib']),
+                           '--build', request['build'], *(['--skip-setup'] if request.get('skip_setup') else []))
+                if addon is None:
+                    plugin = build_plugin(request['target'])
+                    extra = []
+                    for profile in request.get('wallpapers', []):
+                        destination = work / profile
+                        script('make-wallpaper-overlay.py', mount, destination, profile)
+                        extra += ['--wallpaper-floating' if profile.endswith('-floating') else '--wallpaper', destination]
+                    candidate = work / 'gpuaddon.bin'
+                    script('make-gpu-addon.py', '--publish', '--no-daemon', *extra, candidate,
+                           env=dict(os.environ, ADRENO_PLUGIN_DIR=str(plugin)))
+                    if request.get('audio_tool'):
+                        audio = work / 'audio'
+                        run(sys.executable, Path(request['device']) / request['audio_tool'], audio, request['audio_target'])
+                        combined = work / 'combined.bin'
+                        script('addon-add-dir.py', candidate, combined, 'audio/ShengAudio.driver', audio / 'ShengAudio.driver')
+                        candidate = combined
+                    addon = out / 'gpuaddon.bin'
+                    candidate.replace(addon)
+        if trust is None:
+            original = work / 'apple-trust.bundle'
+            script('bundle-ipsw-trust.py', original, *request['trust_modules'])
+            hashes = addon_hashes(addon, work / 'addon')
+            candidate = work / 'owner-trust.bundle'
+            script('trust-append-module.py', original, candidate, *hashes)
+            trust = out / 'owner-trust.bundle'
+            candidate.replace(trust)
+        (out / 'generated.json').write_text(json.dumps(dict(data_ramdisk=str(seed), gpu_addon=str(addon),
+                                                          trust_cache=str(trust)), indent=2) + '\n')
+
+
+if __name__ == '__main__':
+    main()
diff --git a/scripts/build-fileset-release-reference.py b/scripts/build-fileset-release-reference.py
index d903e95..f70ceea 100644
--- a/scripts/build-fileset-release-reference.py
+++ b/scripts/build-fileset-release-reference.py
@@ -10,101 +10,170 @@ import fnmatch
 from pathlib import Path
 import subprocess
 
-repo = Path(__file__).resolve().parents[1]
-parser = argparse.ArgumentParser(description=__doc__)
-parser.add_argument('--tree', required=True, type=Path, help='prepared XNU build tree of the OS profile')
-parser.add_argument('--lto', action='store_true', help='enable the RELEASE default link-time optimization')
-options = parser.parse_args()
-mode = 'lto' if options.lto else 'snapshot'
-root = options.tree.resolve()
-output = root / 'build/xnu/fileset-reference'
-final = output / 'mach.release.bcm2837.unstripped.noctf'
-if final.is_file():
-    # An earlier run of this step left the comparison kernel in place.
-    print(f'reference present: {final}')
-    raise SystemExit(0)
-output.mkdir(parents=True, exist_ok=True)
-source = output / 'source'
-if not source.exists():
-    shutil.copytree(root/'.cache/xnu-work', source, symlinks=True,
-                    ignore=shutil.ignore_patterns('.git'))
-    # The shared tree currently has this observation hook at file scope. The
-    # reference build disables observation hooks; repair only its private copy.
-    sleh = source / 'osfmk/arm64/sleh.c'
-    text = sleh.read_text()
-    misplaced = '\n\tboot_progress_user_breakpoint(state, esr);\n#if __has_feature(ptrauth_calls)'
-    if misplaced in text:
-        sleh.write_text(text.replace(misplaced, '\n#if __has_feature(ptrauth_calls)', 1))
-    manifest = {str(p.relative_to(source)): hashlib.sha256(p.read_bytes()).hexdigest()
-                for p in source.rglob('*') if p.is_file()}
-    (output/'source-sha256.json').write_text(json.dumps(manifest,indent=2)+'\n')
-sdk = root / '.cache/fakeroot'
-archives = [root/'build/corecrypto-2023/libcorecrypto_kernel_noasm-namespaced.a']
-forced = [root/f'build/{folder}/{name}' for folder,name in (
-    ('libpthread-kernel','libpthread_kernel.a'),('armdt-platform','libArmDTPlatform.a'),('armcpu','libArmCpu.a'))]
-assert all(p.is_file() for p in archives+forced)
-env = dict(os.environ, KERNEL_SDKROOT=str(sdk),
-           XNU_AVAILABILITY_PL=str(sdk/'usr/local/libexec/availability.pl'))
-flags = '-Wno-reserved-identifier -Wno-pre-c11-compat -Wno-missing-designated-field-initializers -Wno-suggest-override -Wno-unnecessary-virtual-specifier -Wno-suggest-destructor-override -Wno-ms-bitfield-padding -DXNU_NATIVE_PAN=1 -DXNU_SOURCE_CORECRYPTO14=1 -DXNU_BOOT_PROGRESS=0'
-args = ['make','-C',str(source),'build','SDKROOT=iphoneos',
-    'ARCH_CONFIGS=ARM64','MACHINE_CONFIGS=BCM2837','KERNEL_CONFIGS=RELEASE',
-    'ARCH_STRING_FOR_CURRENT_MACHINE_CONFIG=arm64e','LARGE_MEMORY_DEFINE=-UARM_LARGE_MEMORY',
-    'ARM64_LINK_ADDR=0xfffffff007004000','ARM64_PLKSEG_ADDR=0xfffffff004004000',
-    f'DEPLOYMENT_TARGET_FLAGS=-miphoneos-version-min={os.environ.get("UNIXNU_IOS_VERSION", "26.0")} -DXNU_TARGET_OS_IOS',
-    f'DEPLOYMENT_LINKER_FLAGS=-Wl,-ios_version_min,{os.environ.get("UNIXNU_IOS_VERSION", "26.0")}',
-    f'RC_DARWIN_KERNEL_VERSION={os.environ.get("UNIXNU_XNU_DARWIN", "25.5.0")}',
-    f'RC_ProjectSourceVersion={os.environ.get("UNIXNU_XNU_VERSION", "12377.121.6")}',
-    f'BUILD_LTO={int(options.lto)}','BOUND_CHECKS=0','BUILD_WERROR=0','MAKEJOBS=-j8',
-    'LDFLAGS_KERNEL_LTO=-miphoneos-version-min=26.0 -Wl,-mllvm,-inline-threshold=100',
-    f'CFLAGS_EXTRA={flags}',
-    'copyio.o_CFLAGS_ADD=-march=armv8.1-a','pcb.o_CFLAGS_ADD=-march=armv8.1-a',
-    'LD_KERNEL_ARCHIVES='+' '.join([f'-L{sdk}/usr/local/lib/kernel','-lfirehose_kernel',
-                                    *map(str,archives),*(f'-Wl,-force_load,{p}' for p in forced)]),
-    'XNU_EXTERNAL_KERNEL_ARCHIVES='+' '.join(map(str,archives+forced)),
-    f'OBJROOT={output}/{mode}-obj',f'SYMROOT={output}/{mode}-sym',f'DSTROOT={output}/{mode}-dst']
-(output/f'{mode}-command.json').write_text(json.dumps(args,indent=2)+'\n')
-with (output/f'{mode}-build.log').open('w') as log:
-    result = subprocess.run(args,cwd=root,env=env,stdout=log,stderr=subprocess.STDOUT)
-print('RELEASE reference exit',result.returncode,'log',output/f'{mode}-build.log',flush=True)
-# The bring-up patch calls native hooks from the kernel core behind weak_import declarations; on arm64e
-# the authenticated pointer of an undefined weak symbol fails the link. The private copy stubs them: this
-# comparison kernel never runs, the prelink step reads its layout.
-build_log = (output / f'{mode}-build.log').read_text()
-stub_names = sorted(set(re.findall(r'^\s+"(_(?:native_[a-z0-9_]+|boot_log_rounds))"', build_log, re.M)))
-if stub_names:
-    (output / 'native-stubs.c').write_text(''.join(f'long {name[1:]};\n' for name in stub_names))   # the linker names carry the leading underscore
-    iphoneos = subprocess.check_output(['xcrun', '--sdk', 'iphoneos', '--show-sdk-path'], text=True).strip()
-    subprocess.run(['xcrun', 'clang', '-arch', 'arm64e', '-mkernel', '-isysroot', iphoneos, '-c',
-                    '-o', str(output / 'native-stubs.o'), str(output / 'native-stubs.c')], check=True)
-    at = next(i for i, a in enumerate(args) if a.startswith('LD_KERNEL_ARCHIVES='))
-    args[at] += f' -Wl,-force_load,{output}/native-stubs.o'
-# Forced exports the built objects cannot provide: remove them from this private copy and link again
-# (the symbols are absent from the comparison kernel either way; the first link can stop exactly there,
-# and its file list is what names the objects that were built).
-objects = (output / f'{mode}-obj/RELEASE_ARM64_BCM2837/link.filelist').read_text().splitlines()
-names = set()
-for i in range(0, len(objects), 100):
-    listed = subprocess.run(['xcrun', 'nm', '-gUj', *objects[i:i + 100]], capture_output=True, text=True, check=True)
-    names.update(symbol for symbol in listed.stdout.splitlines() if symbol.startswith('_') and ' ' not in symbol)
-removed = []
-for filename in ('Private.exports', 'Private.arm64.exports'):
-    path = output / 'source/config' / filename
-    lines = path.read_text().splitlines(keepends=True)
-    rejected = {line.strip() for line in lines
-                if line.strip().startswith('_') and ':' not in line and not any(fnmatch.fnmatchcase(n, line.strip()) for n in names)}
-    removed.extend(sorted(rejected))
-    path.write_text(''.join(line for line in lines if line.strip() not in rejected))
-import json as _json
-record = output / 'omitted-unavailable-forced-exports.json'
-previous = _json.loads(record.read_text()) if record.exists() else []
-record.write_text(_json.dumps(sorted(set(previous + removed)), indent=2) + chr(10))
-print('removed', len(removed), 'unavailable forced exports; linking again')
-with (output / f'{mode}-build.log').open('a') as log:
-    result = subprocess.run(args, cwd=root, env=env, stdout=log, stderr=subprocess.STDOUT)
-print('RELEASE reference exit', result.returncode, 'log', output / f'{mode}-build.log', flush=True)
-if result.returncode:
-    raise SystemExit(result.returncode)
-import shutil as _shutil
-built = output / f'{mode}-obj/RELEASE_ARM64_BCM2837/mach.release.bcm2837.unstripped'
-_shutil.copyfile(built, final)
-print('reference', final)
+
+def file_hash(path):
+    with path.open('rb') as stream:
+        return hashlib.file_digest(stream, 'sha256').hexdigest()
+
+
+def tree_hash(path):
+    """Hash inputs by content; follow SDK header-directory links as the compiler does."""
+    if not path.is_dir():
+        raise FileNotFoundError(path)
+    digest = hashlib.sha256()
+    for directory, dirs, files in os.walk(path, followlinks=True):
+        dirs[:] = sorted(d for d in dirs if d != '.git')
+        for name in sorted(files):
+            item = Path(directory) / name
+            digest.update(str(item.relative_to(path)).encode() + b'\0')
+            digest.update(file_hash(item).encode() + b'\0')
+    return digest.hexdigest()
+
+
+def reusable(final, record, inputs):
+    try:
+        saved = json.loads(record.read_text())
+        return saved['inputs'] == inputs and saved['sha256'] == file_hash(final)
+    except (OSError, ValueError, KeyError):
+        return False
+
+
+def linked_objects(directory, lto):
+    if lto:
+        # XNU splits the final link into non-LTO objects and the code generated
+        # by its intermediate LTO link. There is no link.filelist in this mode.
+        objects = (directory / 'nonltolink.filelist').read_text().splitlines()
+        generated = directory / 'justlto.o'
+        objects += [str(p) for p in sorted(generated.glob('*.o'))] if generated.is_dir() else [str(generated)]
+    else:
+        objects = (directory / 'link.filelist').read_text().splitlines()
+        objects += [str(directory / name) for name in
+                    ('version.o', 'lastkerneldataconst.o', 'lastkernelconstructor.o')
+                    if (directory / name).is_file()]
+    return [str(Path(name) if Path(name).is_absolute() else directory / name)
+            for name in objects if name.strip()]
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--tree', required=True, type=Path, help='prepared XNU build tree of the OS profile')
+    parser.add_argument('--lto', action='store_true', help='enable the RELEASE default link-time optimization')
+    options = parser.parse_args()
+    mode = 'lto' if options.lto else 'snapshot'
+    root = options.tree.resolve()
+    build_root = root / 'build/xnu/fileset-reference'
+    final = build_root / 'mach.release.bcm2837.unstripped.noctf'
+    cache_record = final.with_suffix('.json')
+    sdk = root / '.cache/fakeroot'
+    archives = [root/'build/corecrypto-2023/libcorecrypto_kernel_noasm-namespaced.a']
+    forced = [root/f'build/{folder}/{name}' for folder,name in (
+        ('libpthread-kernel','libpthread_kernel.a'),('armdt-platform','libArmDTPlatform.a'),('armcpu','libArmCpu.a'))]
+    inputs = {
+        'mode': mode,
+        'script': file_hash(Path(__file__)),
+        'source': tree_hash(root / '.cache/xnu-work'),
+        'sdk': tree_hash(sdk),
+        'archives': {str(p.relative_to(root)): file_hash(p) for p in archives + forced},
+        'versions': {name: os.environ.get(name, default) for name, default in (
+            ('UNIXNU_IOS_VERSION', '26.0'), ('UNIXNU_XNU_DARWIN', '25.5.0'),
+            ('UNIXNU_XNU_VERSION', '12377.121.6'))},
+        'compiler': subprocess.check_output(['xcrun', 'clang', '--version'], text=True),
+        'environment': {name: value for name, value in os.environ.items()
+                        if name.startswith(('XNU_', 'RC_', 'CCC_')) or name in ('CC', 'CXX', 'LD')},
+    }
+    if reusable(final, cache_record, inputs):
+        print(f'reference inputs and digest match ({mode}): {final}')
+        return
+    # Separate workspaces prevent non-LTO objects and stale patched sources from
+    # being reused after a mode, source, SDK, archive or compiler change.
+    key = hashlib.sha256(json.dumps(inputs, sort_keys=True).encode()).hexdigest()
+    output = build_root / f'{mode}-{key[:16]}'
+    output.mkdir(parents=True, exist_ok=True)
+    (output / 'inputs.json').write_text(json.dumps(inputs, indent=2) + '\n')
+    source = output / 'source'
+    if not source.exists():
+        shutil.copytree(root/'.cache/xnu-work', source, symlinks=True,
+                        ignore=shutil.ignore_patterns('.git'))
+        # The shared tree currently has this observation hook at file scope. The
+        # reference build disables observation hooks; repair only its private copy.
+        sleh = source / 'osfmk/arm64/sleh.c'
+        text = sleh.read_text()
+        misplaced = '\n\tboot_progress_user_breakpoint(state, esr);\n#if __has_feature(ptrauth_calls)'
+        if misplaced in text:
+            sleh.write_text(text.replace(misplaced, '\n#if __has_feature(ptrauth_calls)', 1))
+        manifest = {str(p.relative_to(source)): hashlib.sha256(p.read_bytes()).hexdigest()
+                    for p in source.rglob('*') if p.is_file()}
+        (output/'source-sha256.json').write_text(json.dumps(manifest,indent=2)+'\n')
+    env = dict(os.environ, KERNEL_SDKROOT=str(sdk),
+               XNU_AVAILABILITY_PL=str(sdk/'usr/local/libexec/availability.pl'))
+    flags = '-Wno-reserved-identifier -Wno-pre-c11-compat -Wno-missing-designated-field-initializers -Wno-suggest-override -Wno-unnecessary-virtual-specifier -Wno-suggest-destructor-override -Wno-ms-bitfield-padding -DXNU_NATIVE_PAN=1 -DXNU_SOURCE_CORECRYPTO14=1 -DXNU_BOOT_PROGRESS=0'
+    args = ['make','-C',str(source),'build','SDKROOT=iphoneos',
+        'ARCH_CONFIGS=ARM64','MACHINE_CONFIGS=BCM2837','KERNEL_CONFIGS=RELEASE',
+        'ARCH_STRING_FOR_CURRENT_MACHINE_CONFIG=arm64e','LARGE_MEMORY_DEFINE=-UARM_LARGE_MEMORY',
+        'ARM64_LINK_ADDR=0xfffffff007004000','ARM64_PLKSEG_ADDR=0xfffffff004004000',
+        f'DEPLOYMENT_TARGET_FLAGS=-miphoneos-version-min={os.environ.get("UNIXNU_IOS_VERSION", "26.0")} -DXNU_TARGET_OS_IOS',
+        f'DEPLOYMENT_LINKER_FLAGS=-Wl,-ios_version_min,{os.environ.get("UNIXNU_IOS_VERSION", "26.0")}',
+        f'RC_DARWIN_KERNEL_VERSION={os.environ.get("UNIXNU_XNU_DARWIN", "25.5.0")}',
+        f'RC_ProjectSourceVersion={os.environ.get("UNIXNU_XNU_VERSION", "12377.121.6")}',
+        f'BUILD_LTO={int(options.lto)}','BOUND_CHECKS=0','BUILD_WERROR=0','MAKEJOBS=-j8',
+        f'LDFLAGS_KERNEL_LTO=-miphoneos-version-min={inputs["versions"]["UNIXNU_IOS_VERSION"]} -Wl,-mllvm,-inline-threshold=100',
+        f'CFLAGS_EXTRA={flags}',
+        'copyio.o_CFLAGS_ADD=-march=armv8.1-a','pcb.o_CFLAGS_ADD=-march=armv8.1-a',
+        'LD_KERNEL_ARCHIVES='+' '.join([f'-L{sdk}/usr/local/lib/kernel','-lfirehose_kernel',
+                                        *map(str,archives),*(f'-Wl,-force_load,{p}' for p in forced)]),
+        'XNU_EXTERNAL_KERNEL_ARCHIVES='+' '.join(map(str,archives+forced)),
+        f'OBJROOT={output}/{mode}-obj',f'SYMROOT={output}/{mode}-sym',f'DSTROOT={output}/{mode}-dst']
+    (output/f'{mode}-command.json').write_text(json.dumps(args,indent=2)+'\n')
+    with (output/f'{mode}-build.log').open('w') as log:
+        result = subprocess.run(args,cwd=root,env=env,stdout=log,stderr=subprocess.STDOUT)
+    print('RELEASE reference exit',result.returncode,'log',output/f'{mode}-build.log',flush=True)
+    # The bring-up patch calls native hooks from the kernel core behind weak_import declarations; on arm64e
+    # the authenticated pointer of an undefined weak symbol fails the link. The private copy stubs them: this
+    # comparison kernel never runs, the prelink step reads its layout.
+    build_log = (output / f'{mode}-build.log').read_text()
+    stub_names = sorted(set(re.findall(r'^\s+"(_(?:native_[a-z0-9_]+|boot_log_rounds))"', build_log, re.M)))
+    if stub_names:
+        (output / 'native-stubs.c').write_text(''.join(f'long {name[1:]};\n' for name in stub_names))   # the linker names carry the leading underscore
+        iphoneos = subprocess.check_output(['xcrun', '--sdk', 'iphoneos', '--show-sdk-path'], text=True).strip()
+        subprocess.run(['xcrun', 'clang', '-arch', 'arm64e', '-mkernel', '-isysroot', iphoneos, '-c',
+                        '-o', str(output / 'native-stubs.o'), str(output / 'native-stubs.c')], check=True)
+        at = next(i for i, a in enumerate(args) if a.startswith('LD_KERNEL_ARCHIVES='))
+        args[at] += f' -Wl,-force_load,{output}/native-stubs.o'
+    # Forced exports the built objects cannot provide: remove them from this private copy and link again
+    # (the symbols are absent from the comparison kernel either way; the first link can stop exactly there,
+    # and its file list is what names the objects that were built).
+    objects = linked_objects(output / f'{mode}-obj/RELEASE_ARM64_BCM2837', options.lto)
+    objects += list(map(str, archives + forced))
+    names = set()
+    for i in range(0, len(objects), 100):
+        listed = subprocess.run(['xcrun', 'nm', '-gUj', *objects[i:i + 100]], capture_output=True, text=True, check=True)
+        names.update(symbol for symbol in listed.stdout.splitlines() if symbol.startswith('_') and ' ' not in symbol)
+    removed = []
+    for filename in ('Private.exports', 'Private.arm64.exports'):
+        path = output / 'source/config' / filename
+        lines = path.read_text().splitlines(keepends=True)
+        rejected = {line.strip() for line in lines
+                    if line.strip().startswith('_') and ':' not in line and not any(fnmatch.fnmatchcase(n, line.strip()) for n in names)}
+        removed.extend(sorted(rejected))
+        path.write_text(''.join(line for line in lines if line.strip() not in rejected))
+    import json as _json
+    record = output / 'omitted-unavailable-forced-exports.json'
+    previous = _json.loads(record.read_text()) if record.exists() else []
+    record.write_text(_json.dumps(sorted(set(previous + removed)), indent=2) + chr(10))
+    print('removed', len(removed), 'unavailable forced exports; linking again')
+    with (output / f'{mode}-build.log').open('a') as log:
+        result = subprocess.run(args, cwd=root, env=env, stdout=log, stderr=subprocess.STDOUT)
+    print('RELEASE reference exit', result.returncode, 'log', output / f'{mode}-build.log', flush=True)
+    if result.returncode:
+        raise SystemExit(result.returncode)
+    built = output / f'{mode}-obj/RELEASE_ARM64_BCM2837/mach.release.bcm2837.unstripped'
+    temporary = final.with_suffix('.tmp')
+    shutil.copyfile(built, temporary)
+    os.replace(temporary, final)
+    cache_record.write_text(json.dumps({'inputs': inputs, 'sha256': file_hash(final),
+                                  'build': str(output)}, indent=2) + '\n')
+    print('reference', final)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/scripts/check-unixnu.py b/scripts/check-unixnu.py
index d8942d9..988ec15 100755
--- a/scripts/check-unixnu.py
+++ b/scripts/check-unixnu.py
@@ -90,6 +90,23 @@ def main():
         except Error:
             pass
     expect(payload.check_args(['-v', 'a=1', 'b=x,y']) == '-v a=1 b=x,y', 'kernel arguments')
+    with tempfile.TemporaryDirectory() as name:
+        root = Path(name)
+        (root / 'configs').mkdir()
+        (root / 'configs/boot_defconfig').write_text('CONFIG_XNU_OWNER_DATA_MOUNT=y\n')
+        ctx = argparse.Namespace(config={}, config_path=root / '.config', config_name='boot_defconfig', device=root)
+        for configured in (False, True):
+            if configured:
+                ctx.config_path.write_text('CONFIG_XNU_OWNER_DATA_MOUNT=y\n')
+                ctx.config = parse_config(ctx.config_path.read_text())
+            try:
+                payload.check_data_input(ctx, None)
+                expect(False, 'owner Data payload accepted without its seed')
+            except Error as error:
+                expect('--data-ramdisk' in str(error), 'missing seed diagnostic')
+            payload.check_data_input(ctx, root / 'seed.dbr')
+        ctx.config = {'XNU_OWNER_DATA_MOUNT': False}
+        payload.check_data_input(ctx, None)
     for bad in (['a b'], ['x' * 1100], ['a;b']):
         try:
             payload.check_args(bad)
diff --git a/scripts/make-data-seed.py b/scripts/make-data-seed.py
new file mode 100644
index 0000000..eeaf3cb
--- /dev/null
+++ b/scripts/make-data-seed.py
@@ -0,0 +1,103 @@
+#!/usr/bin/env python3
+"""Create a first-install APFS Data seed from a read-only IPSW OS mount.
+
+The resulting seed is installation state. Keep it for subsequent builds: APFS
+UUIDs and transaction metadata make a new invocation a different installation.
+"""
+import argparse
+import json
+import os
+from pathlib import Path
+import plistlib
+import shutil
+import stat
+import subprocess
+import sys
+import tempfile
+
+ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(ROOT / 'drivers/DarwinBoot/Test'))
+import packed_ramdisk
+
+
+def merge(mount, home, name, values):
+    path = mount / home / 'Library/Preferences' / (name + '.plist')
+    path.parent.mkdir(parents=True, exist_ok=True)
+    content = plistlib.loads(path.read_bytes()) if path.is_file() else {}
+    content.update(values)
+    path.write_bytes(plistlib.dumps(content, fmt=plistlib.FMT_BINARY))
+    path.chmod(0o644)
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('os_mount', type=Path)
+    parser.add_argument('output', type=Path)
+    parser.add_argument('--gib', type=int, required=True)
+    parser.add_argument('--build', required=True)
+    parser.add_argument('--skip-setup', action='store_true')
+    args = parser.parse_args()
+    source = args.os_mount / 'private/var'
+    if not (args.os_mount / 'sbin/launchd').is_file() or not source.is_dir():
+        parser.error('not an IPSW OS volume')
+    if args.output.exists():
+        parser.error('refuse to overwrite an existing installation seed')
+    if not 3 <= args.gib <= 1024:
+        parser.error('--gib must be in 3..1024')
+    args.output.parent.mkdir(parents=True, exist_ok=True)
+    with tempfile.TemporaryDirectory(prefix='new-data-', dir=args.output.parent) as td:
+        work = Path(td)
+        raw = work / 'seed.cdr'
+        subprocess.run(['hdiutil', 'create', '-size', '32m', '-layout', 'NONE', '-fs', 'APFS',
+                        '-volname', 'Data', '-type', 'UDTO', raw], check=True)
+        mount = work / 'mount'
+        mount.mkdir()
+        attached = plistlib.loads(subprocess.check_output(['hdiutil', 'attach', '-nobrowse', '-owners', 'off',
+                                                           '-mountpoint', mount, '-plist', raw]))
+        device = attached['system-entities'][0]['dev-entry']
+        try:
+            for current, dirs, files in os.walk(source, followlinks=False):
+                dirs[:] = [name for name in dirs if name != 'staged_system_apps']
+                dest = mount / Path(current).relative_to(source)
+                dest.mkdir(exist_ok=True)
+                dest.chmod(stat.S_IMODE(Path(current).stat().st_mode))
+                for name in list(dirs) + files:
+                    src, dst = Path(current) / name, dest / name
+                    if src.is_symlink():
+                        dst.symlink_to(os.readlink(src))
+                        if name in dirs:
+                            dirs.remove(name)
+                    elif src.is_file():
+                        shutil.copy2(src, dst)
+            for name in ('keybags', 'mobile/tmp', 'tmp', 'run', 'containers/Bundle',
+                         'containers/Data/System', 'containers/Shared/SystemGroup', 'containers/Temp'):
+                (mount / name).mkdir(parents=True, exist_ok=True)
+            (mount / 'tmp').chmod(0o1777)
+            if args.skip_setup:
+                merge(mount, 'mobile', 'com.apple.purplebuddy', dict(SetupDone=True,
+                      SetupFinishedAllSteps=True, SetupVersion=11, daemonizeNeedsToRun=False))
+                merge(mount, 'mobile', 'com.apple.purplebuddy.notbackedup', {name: False for name in (
+                    'ShouldRunDiagnosticsMiniBuddy', 'ShouldRunHSA2MiniBuddy', 'ShouldRunKeychainSyncMiniBuddy',
+                    'ShouldRunMesaMiniBuddy', 'ShouldRunPaymentMiniBuddy', 'ShouldRunStandardMiniBuddy', 'SilentICDPUpgrade')})
+                merge(mount, 'mobile', 'com.apple.managedconfiguration.notbackedup',
+                      dict(LockdownActivationIndicatesCloudConfigurationAvailable=False))
+                merge(mount, 'mobile', 'com.apple.springboard', dict(BKNoWatchdogs=True,
+                      FBLaunchWatchdogExceptions={'com.apple.purplebuddy': 100.0}, MCForceShowCloudConfigurationUI=False))
+                merge(mount, 'mobile', 'com.apple.migration', dict(LastSystemVersion=args.build,
+                      DMUserDataDisposition=dict(SyntheticDidUpgrade=False, buildVersion=args.build)))
+            for home in ('root', 'mobile'):
+                for name in ('backboardd', '.GlobalPreferences'):
+                    merge(mount, home, name, dict(CAEnableDeepFramebuffer=False,
+                          CAEnableFramebufferCompression=False, CAEnableIOSurfaceCompression=False))
+        finally:
+            subprocess.run(['hdiutil', 'detach', device], check=True)
+        base = work / 'base.dbr'
+        packed_ramdisk.pack(raw, base)
+        candidate = work / 'data.dbr'
+        subprocess.run([sys.executable, ROOT / 'scripts/seed-data-grow.py', '--gib', str(args.gib), base, candidate], check=True)
+        candidate.replace(args.output)
+    print(json.dumps(dict(output=str(args.output), first_install=True, preserve_for_future_builds=True)))
+
+
+if __name__ == '__main__':
+    main()
diff --git a/scripts/policies/ipados-27.0.1-24A446/prelink-regression.json b/scripts/policies/ipados-27.0.1-24A446/prelink-regression.json
new file mode 100644
index 0000000..d04d4a6
--- /dev/null
+++ b/scripts/policies/ipados-27.0.1-24A446/prelink-regression.json
@@ -0,0 +1,62 @@
+{
+  "kernelcache_sha256": "38e6d9fa5f789b8228f4617ef4c6d2a3fd8ab564abdc9b62920f1db53fc1780a",
+  "description": "Remaining unresolved references of the 24A446 startup baseline. This bounds regressions, not runtime qualification.",
+  "required_original_branches": [
+    "__ZN25IOMobileFramebufferLegacyC2EPK11OSMetaClass",
+    "__ZN11IOHIDDevice10handleOpenEP9IOServicejPv"
+  ],
+  "missing": {
+    "com.apple.driver.AppleARMWatchdogTimer": {
+      "0xfffffe00070446a8": 1
+    },
+    "com.apple.iokit.IOHIDFamily": {
+      "0xfffffe000b8b3ce8": 1
+    }
+  },
+  "stubbed": {
+    "com.apple.driver.AppleARMPlatform": {
+      "0xfffffe000aebcc3c": 1,
+      "0xfffffe000aebdee4": 1,
+      "0xfffffe000aebdef4": 1,
+      "0xfffffe000b433e68": 1,
+      "0xfffffe000b4ca1d0": 1,
+      "0xfffffe000b4ca260": 1,
+      "0xfffffe000b4ca2e8": 1
+    },
+    "com.apple.driver.AppleARMWatchdogTimer": {
+      "0xfffffe000ad53f60": 1,
+      "0xfffffe000aebdee4": 1
+    },
+    "com.apple.driver.ApplePMGR": {
+      "0xfffffe000ad6df18": 1,
+      "0xfffffe000ad6e204": 1
+    },
+    "com.apple.iokit.IOCryptoAcceleratorFamily": {
+      "0xfffffe000aec5fe0": 1
+    },
+    "com.apple.iokit.IOGPUFamily": {
+      "0xfffffe000ae14d08": 1
+    },
+    "com.apple.iokit.IOHIDFamily": {
+      "0xfffffe000b417540": 1,
+      "0xfffffe000b430ab8": 1,
+      "0xfffffe000b430bd4": 1
+    },
+    "com.apple.iokit.IOStorageFamily": {
+      "0xfffffe000b430ab8": 1,
+      "0xfffffe000b430bd4": 1
+    },
+    "com.apple.iokit.IOSurface": {
+      "0xfffffe000b4b6724": 1
+    },
+    "com.apple.security.AppleImage4": {
+      "0xfffffe000b5a3ba8": 1
+    },
+    "com.apple.security.Image4": {
+      "0xfffffe000b2a1694": 1,
+      "0xfffffe000b2a170c": 1,
+      "0xfffffe000b2a1778": 1,
+      "0xfffffe000b2a1798": 1
+    }
+  }
+}
diff --git a/scripts/test-fileset-reference.py b/scripts/test-fileset-reference.py
new file mode 100644
index 0000000..3af0e9b
--- /dev/null
+++ b/scripts/test-fileset-reference.py
@@ -0,0 +1,108 @@
+"""A cached comparison kernel must belong to the requested build inputs."""
+import importlib.util
+import json
+import os
+from pathlib import Path
+import tempfile
+from types import SimpleNamespace
+import unittest
+from unittest.mock import patch
+
+spec = importlib.util.spec_from_file_location(
+    'reference', Path(__file__).with_name('build-fileset-release-reference.py'))
+reference = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(reference)
+
+
+class ReferenceCacheTests(unittest.TestCase):
+    def test_lto_filelist_paths_are_relative_to_the_object_directory(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            (root / 'nonltolink.filelist').write_text('lastkernelconstructor.o\nnonlto.o\n')
+            self.assertEqual(reference.linked_objects(root, True),
+                             [str(root / name) for name in
+                              ('lastkernelconstructor.o', 'nonlto.o', 'justlto.o')])
+
+    def test_builder_rebuilds_snapshot_as_lto_then_reuses_matching_output(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            files = ['.cache/xnu-work/osfmk/arm64/sleh.c',
+                     '.cache/xnu-work/config/Private.exports',
+                     '.cache/xnu-work/config/Private.arm64.exports',
+                     '.cache/fakeroot/usr/include/header.h',
+                     'build/corecrypto-2023/libcorecrypto_kernel_noasm-namespaced.a',
+                     'build/libpthread-kernel/libpthread_kernel.a',
+                     'build/armdt-platform/libArmDTPlatform.a',
+                     'build/armcpu/libArmCpu.a']
+            for name in files:
+                path = root / name
+                path.parent.mkdir(parents=True, exist_ok=True)
+                path.write_text('')
+            builds = []
+
+            def make(command, **kwargs):
+                if command[:2] == ['xcrun', 'nm']:
+                    return SimpleNamespace(returncode=0, stdout='')
+                values = dict(arg.split('=', 1) for arg in command if '=' in arg)
+                mode = values['BUILD_LTO']
+                builds.append(mode)
+                output = Path(values['OBJROOT']) / 'RELEASE_ARM64_BCM2837'
+                output.mkdir(parents=True, exist_ok=True)
+                if mode == '1':
+                    (output / 'nonltolink.filelist').write_text('')
+                    (output / 'justlto.o').write_bytes(b'object')
+                else:
+                    (output / 'link.filelist').write_text('')
+                (output / 'mach.release.bcm2837.unstripped').write_text(mode)
+                return SimpleNamespace(returncode=0)
+
+            argv = ['reference', '--tree', str(root)]
+            with patch.object(reference.subprocess, 'run', side_effect=make), \
+                    patch.object(reference.subprocess, 'check_output', return_value='compiler'), \
+                    patch('sys.argv', argv):
+                reference.main()
+                self.assertEqual(builds, ['0', '0'])
+                argv.append('--lto')
+                reference.main()
+                self.assertEqual(builds, ['0', '0', '1', '1'])
+                reference.main()
+                self.assertEqual(builds, ['0', '0', '1', '1'])
+                final = root / 'build/xnu/fileset-reference/mach.release.bcm2837.unstripped.noctf'
+                self.assertEqual(final.read_text(), '1')
+
+    def test_old_snapshot_cannot_satisfy_lto_request(self):
+        with tempfile.TemporaryDirectory() as directory:
+            final = Path(directory) / 'reference'
+            record = Path(directory) / 'record.json'
+            final.write_bytes(b'comparison kernel')
+            snapshot = {'mode': 'snapshot', 'source': 'old'}
+            self.assertFalse(reference.reusable(final, record, snapshot))
+            record.write_text(json.dumps({'inputs': snapshot, 'sha256': reference.file_hash(final)}))
+            self.assertTrue(reference.reusable(final, record, snapshot))
+            self.assertFalse(reference.reusable(final, record, dict(snapshot, mode='lto')))
+            self.assertFalse(reference.reusable(final, record, dict(snapshot, source='changed')))
+            final.write_bytes(b'corrupt kernel')
+            self.assertFalse(reference.reusable(final, record, snapshot))
+
+    def test_source_content_and_linked_sdk_headers_invalidate_cache(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            source = root / 'source'
+            source.mkdir()
+            header = source / 'header.h'
+            header.write_text('old')
+            timestamp = header.stat().st_mtime_ns
+            first = reference.tree_hash(source)
+            header.write_text('new')
+            os.utime(header, ns=(timestamp, timestamp))
+            self.assertNotEqual(first, reference.tree_hash(source))
+            sdk = root / 'sdk'
+            sdk.mkdir()
+            (sdk / 'include').symlink_to(source, target_is_directory=True)
+            first = reference.tree_hash(sdk)
+            header.write_text('next')
+            self.assertNotEqual(first, reference.tree_hash(sdk))
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/scripts/test-runtime-inputs.py b/scripts/test-runtime-inputs.py
new file mode 100644
index 0000000..5a59bcc
--- /dev/null
+++ b/scripts/test-runtime-inputs.py
@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+"""Regressions for first-install input handling and fileset startup gaps."""
+import argparse
+import copy
+import json
+from pathlib import Path
+import struct
+import tempfile
+import unittest
+import uuid
+from unittest.mock import patch
+
+from unixnu.config import parse_config
+from unixnu.kernel import check_prelink_regressions
+from unixnu import runtime
+from unixnu.util import Error
+
+ROOT = Path(__file__).resolve().parents[1]
+IDENTITY = '2A5E9027-D9E1-40F9-983C-41BD3F1994F5'
+
+
+def seed(path):
+    block = bytearray(4096)
+    block[32:36] = b'APSB'
+    block[240:256] = uuid.UUID(IDENTITY).bytes
+    path.write_bytes(struct.pack('<8sIIQQ', b'DBRDISK1', 1, 4096, 4096, 1) + struct.pack('<QQ', 0, 4096) + block)
+
+
+class RuntimeInputs(unittest.TestCase):
+    def context(self, out, explicit=True):
+        work = out / 'runtime'
+        work.mkdir()
+        data = work / 'data.dbr'
+        seed(data)
+        trust, addon = work / 'trust.bundle', work / 'addon.bin'
+        trust.write_bytes(b'trust')
+        addon.write_bytes(b'NGPUADD2')
+        config = out / '.config'
+        config.write_text(f'CONFIG_XNU_OWNER_DATA_MOUNT=y\nCONFIG_XNU_OWNER_DATA_VOLUME_UUID="{IDENTITY}"\n')
+        return argparse.Namespace(
+            board={'payload': {'runtime': {'tool': 'scripts/build-boot-runtime.py'}}},
+            tree=ROOT, device=out, work=out, config_path=config,
+            need_config=lambda: parse_config(config.read_text()),
+            args=argparse.Namespace(data_ramdisk=str(data) if explicit else None,
+                                    owner_trust_cache=str(trust), trust_cache=None, gpu_addon=str(addon), init_data=False))
+
+    def test_reuse_keeps_seed_bytes(self):
+        with tempfile.TemporaryDirectory() as td:
+            ctx = self.context(Path(td))
+            before = Path(ctx.args.data_ramdisk).read_bytes()
+            with patch.object(runtime, 'Ipsw', side_effect=AssertionError('must not fetch or regenerate explicit inputs')):
+                runtime.prepare(ctx, kernel_build=True)
+            self.assertEqual(Path(ctx.args.data_ramdisk).read_bytes(), before)
+            self.assertEqual(runtime.seed_uuid(ROOT, Path(ctx.args.data_ramdisk)), IDENTITY)
+
+    def test_missing_cache_requires_first_install(self):
+        with tempfile.TemporaryDirectory() as td:
+            ctx = self.context(Path(td), explicit=False)
+            (ctx.work / 'runtime/data.dbr').unlink()
+            with patch.object(runtime, 'Ipsw', side_effect=AssertionError('must fail before fetching')):
+                with self.assertRaisesRegex(Error, 'FIRST installation'):
+                    runtime.prepare(ctx, kernel_build=True)
+
+    def test_payload_cannot_change_compiled_uuid(self):
+        with tempfile.TemporaryDirectory() as td:
+            ctx = self.context(Path(td))
+            ctx.config_path.write_text('CONFIG_XNU_OWNER_DATA_VOLUME_UUID="00000000-0000-0000-0000-000000000000"\n')
+            with self.assertRaisesRegex(Error, 'rebuild the kernel'):
+                runtime.prepare(ctx)
+            runtime.prepare(ctx, kernel_build=True)
+            self.assertEqual(ctx.need_config()['XNU_OWNER_DATA_VOLUME_UUID'], IDENTITY)
+
+    def test_new_gap_rejected_but_resolved_gap_allowed(self):
+        policy = dict(missing={}, stubbed={'owner': {'0x1000': 1}}, required_original_branches=['adapter'])
+        record = dict(collection_slide='0x100', missing={}, stubbed={'owner': {'0x1100': 1}},
+                      native_original_branches=[{'symbol': 'adapter'}])
+        check_prelink_regressions(record, policy)
+        worse = copy.deepcopy(record)
+        worse['stubbed']['owner']['0x1200'] = 1
+        with self.assertRaisesRegex(Error, 'prelink regression'):
+            check_prelink_regressions(worse, policy)
+        record['stubbed'] = {}
+        check_prelink_regressions(record, policy)
+        record['native_original_branches'] = []
+        with self.assertRaisesRegex(Error, 'adapter branch'):
+            check_prelink_regressions(record, policy)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/scripts/unixnu/cli.py b/scripts/unixnu/cli.py
index 25773cf..2784bcf 100644
--- a/scripts/unixnu/cli.py
+++ b/scripts/unixnu/cli.py
@@ -5,12 +5,12 @@ import platform
 import shutil
 import sys
 
-from . import bootimg, components, feeds, firmware, ipsw, kernel, package, patches, payload, pipeline, profiles, tree, userdata
+from . import bootimg, components, feeds, firmware, ipsw, kernel, package, patches, payload, pipeline, profiles, runtime, tree, userdata
 from .config import LOCAL_KINDS, Context, parse_config
 from .util import Error, expand, git, log
 
 STEPS = ('kernel', 'package', 'firmware', 'payload')
-OPTIONAL_STEPS = ('userdata',)   # large; built only when named
+OPTIONAL_STEPS = ('userdata', 'runtime')
 
 
 def common():
@@ -34,7 +34,8 @@ def common():
     p.add_argument('--trust-cache', metavar='FILE', help='trust cache bundle for the payload')
     p.add_argument('--owner-trust-cache', metavar='FILE', help='owner-signed trust cache bundle that carries the original caches and extra modules; replaces --trust-cache and skips the board allow-list')
     p.add_argument('--skip-setup', action='store_true', help='mark Setup as done in the Data seed, so the Hello pages are skipped (needs --data-ramdisk; optional)')
-    p.add_argument('--data-ramdisk', metavar='FILE', help='Data ramdisk seed for the payload (an input; not built here)')
+    p.add_argument('--data-ramdisk', metavar='FILE', help='preserved Data ramdisk seed for this installation')
+    p.add_argument('--init-data', action='store_true', help='create and retain a new Data seed from the IPSW for a FIRST installation; requires kernel build')
     p.add_argument('--gpu-addon', metavar='FILE', help='GPU addon file (scripts/make-gpu-addon.py) the kernel writes into the Data volume at boot')
     p.add_argument('--unique-chip-id', metavar='HEX', help='platform seed for the device tree; or UNIXNU_UNIQUE_CHIP_ID')
     p.add_argument('--ipsw', metavar='PATH_OR_URL', help='the target IPSW: a local file or an https URL (default: url of board.toml [ipsw]); or UNIXNU_IPSW')
@@ -158,6 +159,8 @@ def cmd_build(ctx):
     if 'firmware' in steps:
         need_uefi(ctx)   # fail before fetching anything
     modules = prepare(ctx, steps + (['kernel'] if 'prelink' in steps else []))
+    if 'payload' in steps or 'runtime' in steps:
+        runtime.prepare(ctx, kernel_build='kernel' in steps)
     if 'kernel' in steps:
         kernel.build(ctx, modules)
         kernel.prelink(ctx)
diff --git a/scripts/unixnu/kernel.py b/scripts/unixnu/kernel.py
index f9a45e5..ac2723c 100644
--- a/scripts/unixnu/kernel.py
+++ b/scripts/unixnu/kernel.py
@@ -236,6 +236,21 @@ def stage_native(kernel, output):
     return output
 
 
+def check_prelink_regressions(record, policy):
+    """An experimental allow-missing build may improve, but cannot add gaps."""
+    slide = int(record['collection_slide'], 16)
+    for kind in ('missing', 'stubbed'):
+        for owner, targets in record[kind].items():
+            for target, count in targets.items():
+                original = hex((int(target, 16) - slide) & ((1 << 64) - 1))
+                allowed = policy[kind].get(owner, {}).get(original, 0)
+                if count > allowed:
+                    raise Error(f'prelink regression: {kind} {owner} original {original}, {count} sites (allowed {allowed})')
+    branches = {entry['symbol'] for entry in record.get('native_original_branches', [])}
+    if set(policy.get('required_original_branches', [])) - branches:
+        raise Error('prelink lacks required absolute adapter branch relocations')
+
+
 def prelink(ctx):
     """Produce out/<device>/kernel/kernel.macho from the XNU build and the original kernelcache."""
     spec = ctx.board.get('kernel', {}).get('prelink')
@@ -277,6 +292,11 @@ def prelink(ctx):
             run(command + ['--output', candidate], cwd=ctx.tree, log_file=ctx.logs / 'prelink.log')
             if not candidate.is_file():
                 raise Error('prelink completed without writing a kernel candidate')
+            if spec.get('regression_policy'):
+                policy = json.loads((ctx.tree / spec['regression_policy']).read_text())
+                if policy['kernelcache_sha256'] != sha256_file(cache):
+                    raise Error('prelink regression policy names another kernelcache')
+                check_prelink_regressions(json.loads(candidate.with_suffix('.json').read_text()), policy)
             success = True
         finally:
             if candidate_map.is_file():
diff --git a/scripts/unixnu/payload.py b/scripts/unixnu/payload.py
index d7a9867..0774c8e 100644
--- a/scripts/unixnu/payload.py
+++ b/scripts/unixnu/payload.py
@@ -38,6 +38,21 @@ def check_args(arguments):
     return line
 
 
+def check_data_input(ctx, data):
+    """An owner-Data kernel needs a seed even when it resumes a persistent overlay."""
+    if data:
+        return
+    from .config import parse_config
+    config = ctx.config
+    if not ctx.config_path.is_file() and ctx.config_name:
+        selected = ctx.device / 'configs' / ctx.config_name
+        if selected.is_file():
+            config = parse_config(selected.read_text())
+    if config.get('XNU_OWNER_DATA_MOUNT'):
+        raise Error('CONFIG_XNU_OWNER_DATA_MOUNT requires --data-ramdisk FILE (or [build] data_ramdisk); '
+                    'persistent Data still needs its original seed to publish the volume')
+
+
 def check_native_root(kernel, arguments, vmm_present=False):
     """Refuse the known bare-metal AMFI panic before the volume is written.
 
@@ -111,6 +126,7 @@ def build(ctx, kernel=None):
         if allowed and not owner_trust and sha256_file(trust) not in allowed:
             raise Error(f'{trust} is not one of the trust caches this board accepts (board.toml [payload] trust_cache_sha256)')
     data = expand(args.data_ramdisk) if getattr(args, 'data_ramdisk', None) else None
+    check_data_input(ctx, data)
     if data and not data.is_file():
         raise Error(f'Data ramdisk not found: {data}')
     if getattr(args, 'skip_setup', False):
diff --git a/scripts/unixnu/pipeline.py b/scripts/unixnu/pipeline.py
index c0ebd07..fbeac31 100644
--- a/scripts/unixnu/pipeline.py
+++ b/scripts/unixnu/pipeline.py
@@ -38,6 +38,11 @@ def write_manifest(ctx, modules, patch_order, files):
                 'revisions': revisions, 'patches': [str(path) for path in patch_order],
                 'kernel_command_line_bytes': len(command_line(ctx)),
                 'outputs': {name: {'bytes': path.stat().st_size, 'sha256': sha256_file(path)} for name, path in files.items()}}
+    runtime = ctx.work / 'runtime/inputs.json'
+    if runtime.is_file():
+        inputs = json.loads(runtime.read_text())
+        manifest['runtime'] = {'data_volume_uuid': inputs['data_volume_uuid'],
+                               'inputs': {key: value['sha256'] for key, value in inputs['inputs'].items()}}
     target = ctx.work / 'package.manifest.json'
     target.write_text(json.dumps(manifest, indent=2, sort_keys=True) + '\n')
     return target
diff --git a/scripts/unixnu/runtime.py b/scripts/unixnu/runtime.py
new file mode 100644
index 0000000..1edb0fd
--- /dev/null
+++ b/scripts/unixnu/runtime.py
@@ -0,0 +1,112 @@
+"""Prepare reproducible runtime inputs before compiling the kernel.
+
+The board supplies a builder. An existing Data seed is immutable: generating a
+replacement is an explicit first-install operation, never a cache-miss fallback.
+"""
+import importlib.util
+import json
+import os
+import re
+import sys
+import uuid
+from pathlib import Path
+
+from .ipsw import Ipsw
+from .util import Error, log, run, sha256_file
+
+
+def seed_uuid(tree, path):
+    spec = importlib.util.spec_from_file_location('runtime_packed_ramdisk', tree / 'drivers/DarwinBoot/Test/packed_ramdisk.py')
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    _, extents = module.regions(path.read_bytes())
+    identities = set()
+    for _, data in extents:
+        for at in range(0, len(data), 4096):
+            block = data[at:at + 4096]
+            if block[32:36] == b'APSB':
+                identities.add(str(uuid.UUID(bytes=bytes(block[240:256]))).upper())
+    if len(identities) != 1:
+        raise Error(f'{path}: require a packed APFS seed with exactly one volume UUID')
+    return identities.pop()
+
+
+def prepare(ctx, kernel_build=False):
+    spec = ctx.board.get('payload', {}).get('runtime')
+    if not spec or not spec.get('enabled', True):
+        from .payload import check_data_input
+        check_data_input(ctx, getattr(ctx.args, 'data_ramdisk', None))
+        return
+    if getattr(ctx, '_runtime_prepared', False):
+        return
+    args = ctx.args
+    out = ctx.work / 'runtime'
+    out.mkdir(parents=True, exist_ok=True)
+    seed = Path(args.data_ramdisk).expanduser().resolve() if args.data_ramdisk else out / 'data.dbr'
+    init = bool(getattr(args, 'init_data', False))
+    if init and args.data_ramdisk:
+        raise Error('--init-data cannot replace --data-ramdisk; use one first-install seed or reuse the original')
+    if init and not kernel_build:
+        raise Error('--init-data needs a kernel build to bind its new Data volume UUID')
+    if not seed.is_file() and not init:
+        raise Error('No preserved Data seed. Pass --data-ramdisk FILE for an existing installation, '
+                    'or --init-data for a FIRST installation; a missing cache never regenerates Data automatically')
+    previous = out / 'inputs.json'
+    if not args.data_ramdisk and seed.is_file() and previous.is_file():
+        expected = json.loads(previous.read_text())['inputs']['data_ramdisk']['sha256']
+        if sha256_file(seed) != expected:
+            raise Error('Saved Data seed differs from its recorded SHA-256; restore the original installation seed')
+    owner = getattr(args, 'owner_trust_cache', None)
+    trust = owner or getattr(args, 'trust_cache', None)
+    addon = getattr(args, 'gpu_addon', None)
+    for name, path in [('Data seed', args.data_ramdisk), ('trust bundle', trust), ('GPU addon', addon)]:
+        if path and not Path(path).expanduser().is_file():
+            raise Error(f'{name} not found: {path}')
+    # Preserve explicit inputs. A source-built addon must be paired with newly
+    # collected CDHashes, so an explicit trust bundle alone is not sufficient.
+    if trust and not addon:
+        raise Error('Pass both --gpu-addon and its --owner-trust-cache, or omit both to build them from source')
+    request = dict(spec, tree=str(ctx.tree), device=str(ctx.device), output=str(out),
+                   data_ramdisk=str(seed), init_data=init,
+                   gpu_addon=str(Path(addon).expanduser().resolve()) if addon else None,
+                   trust_cache=str(Path(trust).expanduser().resolve()) if trust else None)
+    if not seed.is_file() or not trust or not addon:
+        source = Ipsw(ctx)
+        if not seed.is_file() or not addon:
+            request['os_image'] = str(source.disk_image('OS'))
+        if not trust:
+            request['trust_modules'] = [str(source.extract(name)) for name in spec['trust_components']]
+        request_path = out / 'request.json'
+        request_path.write_text(json.dumps(request, indent=2) + '\n')
+        report = out / 'generated.json'
+        report.unlink(missing_ok=True)
+        run([sys.executable, ctx.tree / spec['tool'], '--request', request_path], cwd=ctx.tree,
+            env=dict(os.environ, UNIXNU_DEVICE=str(ctx.device)), log_file=ctx.logs / 'runtime.log')
+        if not report.is_file():
+            raise Error('runtime builder did not produce generated.json')
+        generated = json.loads(report.read_text())
+        seed = Path(generated['data_ramdisk'])
+        trust, addon = generated['trust_cache'], generated['gpu_addon']
+        owner = trust
+    identity = seed_uuid(ctx.tree, seed)
+    config = ctx.need_config()
+    if identity != config.get('XNU_OWNER_DATA_VOLUME_UUID'):
+        if not kernel_build:
+            raise Error('Data seed UUID differs from the compiled configuration; rebuild the kernel with this seed')
+        text = ctx.config_path.read_text()
+        text, count = re.subn(r'^CONFIG_XNU_OWNER_DATA_VOLUME_UUID=.*$',
+                             f'CONFIG_XNU_OWNER_DATA_VOLUME_UUID="{identity}"', text, flags=re.M)
+        if count != 1:
+            raise Error('runtime Data requires exactly one CONFIG_XNU_OWNER_DATA_VOLUME_UUID')
+        ctx.config_path.write_text(text)
+        ctx.need_config()
+    args.data_ramdisk, args.gpu_addon = str(seed), str(addon)
+    if owner:
+        args.owner_trust_cache = str(trust)
+    else:
+        args.trust_cache = str(trust)
+    inputs = {name: {'path': str(path), 'sha256': sha256_file(Path(path))}
+              for name, path in [('data_ramdisk', seed), ('trust_cache', trust), ('gpu_addon', addon)]}
+    (out / 'inputs.json').write_text(json.dumps(dict(inputs=inputs, data_volume_uuid=identity), indent=2) + '\n')
+    log(f'runtime: Data UUID {identity}; preserved seed sha256 {inputs["data_ramdisk"]["sha256"]}')
+    ctx._runtime_prepared = True