diff --git a/docs/03-tech-stack.md b/docs/03-tech-stack.md
index c29b59c..b341a23 100644
--- a/docs/03-tech-stack.md
+++ b/docs/03-tech-stack.md
@@ -24,8 +24,8 @@
 | 语言 | Go | 已定 | 面向长时间 RTSP 运行、并发控制和单一交付物。 |
 | 模型工件 | 固定输入尺寸的 ONNX Pose 模型 | 已定 | Go 不直接加载 `.pt`；模型由已验收 V1 权重导出并记录哈希。 |
 | 推理运行时 | `github.com/yalue/onnxruntime_go` v1.31.0 + ONNX Runtime CPU DLL | Spike 已验证 | Windows 上以显式 DLL 路径加载锁定的 1×3×640×640 Pose ONNX，已完成一次真实录像首帧推理；该包装器的 C API 为 26，V2 构建必须启用 CGO/MinGW，并在发布包锁定匹配 DLL 的来源与 SHA-256。 |
-| 视频输入 | 受控的 `ffmpeg.exe` 子进程输出 `bgr24` 原始帧 | Spike 已验证 | 已读取 848×480 本地录像首帧；避免未配置的 GoCV/OpenCV 开发绑定。T-304 必须随应用锁定 FFmpeg/FFprobe 的版本、哈希与 RTSP 重连行为。 |
-| 图像预处理 | Go 实现的 BGR→RGB、CHW、640 letterbox | Spike 已验证，待一致性回归 | 可生成 ONNX 所需 1,228,800 个 float；当前是最小 nearest-neighbour Spike，不得直接当作生产预处理，T-303 必须与 V1 缩放、补边、NMS 和坐标还原逐项对齐。 |
+| 视频输入 | 受控的 `ffmpeg.exe` 子进程输出 `bgr24` 原始帧 | 回放已验证 | Go 回归命令已完整读取 317 帧本地录像；避免未配置的 GoCV/OpenCV 开发绑定。T-304 必须随应用锁定 FFmpeg/FFprobe 的版本、哈希与 RTSP 重连行为。 |
+| 图像预处理与 Pose 解析 | Go 实现的 BGR→RGB、CHW、640 letterbox、NMS、17 点及坐标还原 | 合成契约与无报警回放已验证 | 采用 Ultralytics 的 114 补边、双线性缩放后转 uint8 的语义；Go 首帧输出两个人，与 V1 对应结果的 box 坐标差在已记录的 6 像素容差内。仍需经同意的真实正例录像完成事件级确认。 |
 | 演示 UI | `github.com/lxn/walk`（Windows 原生控件） | Spike 已验证 | 双 Tab 骨架可在 `CGO_ENABLED=0` 编译，避免 Fyne/OpenGL 首次编译的高复杂度；正式版仍须实现浅灰蓝底、白色卡片，红色仅表示确认摔倒。 |
 | 测试 | `go test ./...` + V1 回归录像 | 已定 | V2 行为必须与 V1 基线对照。 |
 
@@ -49,6 +49,7 @@
 | V1 单元测试 | `python -m pytest v1/tests -v` |
 | V2 单元测试 | `Set-Location v2; $env:CGO_ENABLED='1'; go test ./...` |
 | V2 ONNX/视频 Spike | `Set-Location v2; $env:CGO_ENABLED='1'; go run ./cmd/spike --ffmpeg <ffmpeg.exe> --video <local-video> --width <w> --height <h> --onnx assets\best.onnx --ort-dll <onnxruntime.dll>` |
+| V2 录像事件回归 | `Set-Location v2; $env:CGO_ENABLED='1'; go run ./cmd/regression --ffmpeg <ffmpeg.exe> --video <local-video> --width <w> --height <h> --fps <fps> --onnx assets\best.onnx --ort-dll <onnxruntime.dll>` |
 | V2 Walk UI 编译 Spike | `Set-Location v2; $env:CGO_ENABLED='0'; go build ./cmd/ui-spike` |
 
 ## 演进决策
diff --git a/docs/04-architecture.md b/docs/04-architecture.md
index 75b8408..d6a1e1c 100644
--- a/docs/04-architecture.md
+++ b/docs/04-architecture.md
@@ -26,7 +26,7 @@ Pose 推理适配器（person box + 17 keypoints）
 
 V1 的同一数据流既可接 RTSP，也可回放本地录像。V2 复用同一配置、事件字段和录像集，但将 Pose 推理替换为 ONNX 适配器；不得改变事件语义。
 
-T-302 的实现路线为：受控 `ffmpeg.exe` 负责解码为 BGR 原始帧，Go 预处理模块生成固定 `1×3×640×640` RGB/CHW tensor，`onnxruntime_go` 以显式 DLL 路径执行 Pose ONNX，Windows Walk UI 只接收已完成渲染的数据。解码、推理和事件计算都不得在 UI 消息线程运行；UI 只显示最新完成帧和事件状态。T-303 必须先补齐与 V1 一致的 letterbox、NMS、17 点解析、坐标还原、跟踪和状态机，才可以接入实时 UI。
+T-302/T-303 的实现路线为：受控 `ffmpeg.exe` 负责解码为 BGR 原始帧，Go 预处理模块以 114 补边、双线性缩放与 RGB/CHW 生成固定 `1×3×640×640` tensor，`onnxruntime_go` 以显式 DLL 路径执行 Pose ONNX，随后由 NMS、17 点解析、坐标还原、轻量跟踪、质量/几何证据、倒地策略和四态状态机生成不变的 `FallEvent`。Windows Walk UI 只接收已完成渲染的数据。解码、推理和事件计算都不得在 UI 消息线程运行；UI 只显示最新完成帧和事件状态。
 
 ## 模块职责
 
@@ -48,15 +48,15 @@ T-302 的实现路线为：受控 `ffmpeg.exe` 负责解码为 BGR 原始帧，G
 | 应用装配 | `v1/app.py` | 装配配置、Pose、管线线程与窗口；`FrameWorker` 只发出已判定的 `FrameAnalysis` | 事件判定、渲染细节 |
 | 回归工具 | `v1/tests/` 与 `v1/scripts/` | 回放录像、断言事件和延迟 | 生产 UI |
 
-V2 对应模块将在 T-303/T-304 建立，职责预先固定如下：
+V2 对应模块的当前落实与 T-304 目标如下：
 
 | 模块 | V2 目标位置 | 职责 | 不负责 |
 | --- | --- | --- | --- |
-| 解码器 | `v2/internal/video` | 启动受控 FFmpeg、提供最新 BGR 帧与显式来源状态 | Pose、事件判定、UI 绘制 |
-| ONNX Pose | `v2/internal/pose` | 校验模型/DLL 清单，完成精确预处理、推理、NMS、关键点及坐标还原 | 人员 ID、摔倒结论 |
+| 回放解码器 | `v2/cmd/regression` | 用受控 FFmpeg 顺序读取 BGR 帧，供本机录像回归 | RTSP 重连、UI 绘制 |
+| ONNX Pose | `v2/internal/pose` | 114 letterbox、RGB/CHW、NMS、关键点及坐标还原 | 人员 ID、摔倒结论 |
 | 事件引擎 | `v2/internal/fall` | 复现 V1 的跟踪、证据、四态状态机和 `FallEvent` | 视频解码、声音、文件 |
 | Windows UI | `v2/internal/ui` | Walk 顶部“监控/设置”Tab、渲染最新帧和已计算状态 | 直接读 RTSP、执行 ONNX 或事件规则 |
-| 应用装配 | `v2/cmd/silver-pose` | 管理 worker 生命周期、取消、最新帧投递和依赖注入 | 重写领域规则 |
+| 应用装配 | `v2/cmd/silver-pose`（T-304） | 管理 worker 生命周期、取消、最新帧投递和依赖注入 | 重写领域规则 |
 
 ## UI 导航与配置生效生命周期
 
diff --git a/docs/current-state.md b/docs/current-state.md
index d6e2ed5..7cb414d 100644
--- a/docs/current-state.md
+++ b/docs/current-state.md
@@ -9,13 +9,13 @@
 - 已验证环境：Windows PowerShell；Python 3.8.10；Ultralytics 8.3.205；PyQt5 可导入。注意：当前 WSL/Linux 环境未安装 PyQt5，且其 ultralytics/torch 版本与该基线不兼容（模型前向不可用），故 GUI 可视化与真实模型端到端渲染只在 Windows 验证；本环境用 Qt-free 的 `view_model.py` 单元测试与假适配器管线冒烟覆盖视图逻辑。
 - 旧生产基线：`demo/main.py`、`demo/fall_detection_gui.py`、`demo/detect_fall.py`、`demo/best.pt`。
 - V1 代码：已建立安全配置、显式 Replay/Stream 视频源、Pose、轻量跟踪、质量/几何证据、倒地领域规则、按 ID 四态事件机及 `v1/pipeline.py` 事件管线；运行事件带非敏感 `config_version`，缺帧/低质量/断流会中断证据确认。新增 `v1/view_model.py`（Qt-free 监控视图状态与设置草稿三份隔离）、`v1/gui.py` 薄 PyQt5 双 Tab 外壳与 `v1/app.py` 装配（`FrameWorker` 只发出已判定的 `FrameAnalysis`，窗口只渲染）。新增 `v1/alerts.py`：按 `event_id` 去重，对首次 CONFIRMED 保存带标注截图、追加 JSONL 事件行，并经可注入 `AlertSink`（Windows 侧 `QtAlertSink` 提供声音与一次性弹窗）触发一次声音/弹窗。新增 `v1/camera.py`（RTSP URL 构建 + 有界连接测试抓帧）与 `config.py` 的结构化来源（host/端口/通道/账号/密码，凭证百分号编码）、`write_local_camera_source`；设置页新增摄像头连接分组、测试连接与预览，以及传输协议/连接超时/低延迟三项抓流调优（由 `config` 存值、`app` 开流前写入 `OPENCV_FFMPEG_CAPTURE_OPTIONS`）。真实海康流已用 `VideoSource(STREAM)` 连通（1920×1080）。
-- V2 代码：已创建 Go 模块和受控 Spike。`cmd/spike` 用 FFmpeg 读取本地 BGR 帧、将其预处理为 640 tensor，并用 `onnxruntime_go` 对锁定 ONNX 执行一次推理；`cmd/ui-spike` 是可编译的 Windows Walk 双 Tab 外壳。它们不含 NMS/关键点解析、跟踪、状态机、RTSP、报警或发布打包，不能作为客户演示版。
+- V2 代码：T-303 已落地 `internal/pose`（Ultralytics 114 letterbox、BGR→RGB/CHW、YOLO Pose NMS、17 点及坐标还原）与 `internal/fall`（中心点跟踪、质量/几何证据、策略、四态状态机和事件 ID）；`cmd/regression` 使用 FFmpeg 顺序回放本机录像并将 ONNX Pose 接入事件引擎。`cmd/ui-spike` 仍只是可编译的 Windows Walk 双 Tab 外壳。RTSP 重连、UI 实时渲染、声音、弹窗、截图和发布打包尚未实现，不能作为客户演示版。
 - 非代码设计工件：docs/ui/silver-pose-ui-ux-spec.md、docs/ui/2026-07-20-html-prototype-plan.md、docs/ui/silver-pose-v1-prototype.html 与 docs/ui/silver-pose-v2-prototype.html 已建立。v2 HTML 是符合正式浅色 Windows 规范的当前视觉参考：浅灰蓝底、白色卡片，红色只表示确认摔倒、其弹窗和事件证据；文件名中的 v2 只表示原型设计修订，不能理解为 Go V2 实现已开始。v1 HTML 保留为历史深色对照。两者均使用顶部双 Tab、设置草稿与状态交互，且画面、事件和时间都是模拟数据，不连接真实摄像头、模型或网络，也不改变 Phase 1 任务顺序。
-- 测试：`python -m compileall -q v1 demo` 已通过（含 `gui.py`、`app.py`、`alerts.py`、`camera.py` 语法）；`./init.ps1` 当前运行 V1 测试为 88 passed、1 skipped，覆盖配置、视频源、Pose、跟踪、证据、领域规则、状态机、管线、视图模型、报警工件、摄像头/URL 构建、抓流参数拼串、每帧诊断、灵敏度放宽、截图标注、断流重连、事件汇总、灵敏度写回和最新帧丢弃。T-302 的 `CGO_ENABLED=1 go test ./...` 通过；Go Spike 对 848×480 本地录像首帧生成 1,228,800 元素输入并获得 470,400 元素 ONNX 输出；Walk UI Spike 以 `CGO_ENABLED=0 go build ./cmd/ui-spike` 编译通过。这些只验证管线、视图与报警工件可运行，不表示摔倒识别准确率或 Go 行为等价。`init.ps1` 会检查运行时依赖、编译旧基线并运行 V1 测试，但不会安装软件包。
+- 测试：`python -m compileall -q v1 demo` 已通过（含 `gui.py`、`app.py`、`alerts.py`、`camera.py` 语法）；`./init.ps1` 当前运行 V1 测试为 88 passed、1 skipped。T-303 的 `CGO_ENABLED=1 go test ./...` 通过。对同一 317 帧本机录像，V1 回放得到 253 个有人帧、263 人次、0 个 CONFIRMED；Go 回放得到 255 个有人帧、265 人次、0 个 CONFIRMED。人次差异来自 OpenCV/FFmpeg 解码像素不同，二者的无报警事件结论一致；Go 合成正例契约和 V1 状态机均在 1.81 秒时产生一个 CONFIRMED。Walk UI Spike 以 `CGO_ENABLED=0 go build ./cmd/ui-spike` 编译通过。这些不表示摔倒识别准确率或完整 Go 客户演示已验收。`init.ps1` 会检查运行时依赖、编译旧基线并运行 V1 测试，但不会安装软件包。
 - 模型：`demo/best.pt` 可加载为 YOLO Pose，类别 `person`，`kpt_shape=[17, 3]`；与 `D:\PythonP\fall_detection\best.pt` 哈希一致。
 - 当前标准启动：`./init.ps1`。
 - 当前标准验证：`python -m compileall -q demo`。
-- 当前 blocker：没有 T-303 的代码阻塞；但 Go 尚未验证与 V1 的预后处理、NMS、关键点、跟踪、状态机和事件延迟一致，不能把 T-302 的单帧推理表述为可演示的 V2。ONNX Runtime DLL、FFmpeg/FFprobe 仍须在 T-304 以版本、来源和哈希纳入发布包；现场录像和事件工件保持本机不提交。
+- 当前 blocker：T-303 缺少经同意的、可在本机回放的正例摔倒录像及其 V1 基线；因此尚不能证明同一真实正例录像在 Go 中也确认且延迟为 1–3 秒。Go/V1 无报警回放和纯领域正例契约均已通过，但不能替代录像级正例。ONNX Runtime DLL、FFmpeg/FFprobe 仍须在 T-304 以版本、来源和哈希纳入发布包；现场录像和事件工件保持本机不提交。
 
 全局环境的 `pip check` 存在其他项目的包冲突，因此它不是 Silver Pose 的验收命令。`init.ps1` 只检查本项目实际导入的 OpenCV、NumPy、Ultralytics 与 PyQt5，并在命令非零退出时失败。
 
@@ -25,7 +25,7 @@
 | --- | --- | --- |
 | `demo/` | 已有 | 旧 Python GUI、Pose 模型与样例视频；当前单帧规则不适合作为正式事件逻辑。 |
 | `v1/` | 已验收 | Python V1 正式实现、现场验收记录与发布工具。 |
-| `v2/` | Spike 已完成 | Go 模块、ONNX/视频命令行 Spike 与 Windows Walk UI 外壳；尚不是完整 V2。 |
+| `v2/` | T-303 部分完成 | Go ONNX 后处理、事件引擎和本机录像无报警回归已实现；尚不是完整 V2。 |
 | `docs/` | 已有 | Harness Coding 文档、任务和计划。 |
 | `tests/` | 不适用 | V1 测试将在 `v1/tests/` 下创建。 |
 | `artifacts/` | 待创建 | 本地事件截图和 JSONL，不提交。 |
@@ -33,7 +33,6 @@
 ## 任务状态
 
 - 已完成：T-000、T-101~T-106（V1 地基与事件管线）、T-201（PyQt 双 Tab）、T-202（本地报警/截图/JSONL）、T-203（海康 RTSP 与断流恢复）、T-204（正反例录像与现场验收）、T-205（客户演示脚本与发布包）、T-206（结构化摄像头配置与连接测试）、T-207（抓流低延迟参数）、T-208（每帧诊断叠加）、T-209（放宽俯视灵敏度）、T-210（截图 ASCII 标注）、T-211（灵敏度设置页）、T-212（实时流最新帧）、T-213（截图中文标注）、T-301（ONNX 一致性）、T-302（Go 推理、视频/UI Spike）。
-- 正在进行：无。
 - 正在进行：T-303（实现 Go 事件引擎与 V1 回归对比）。
 
 ## 当前可运行内容
@@ -42,6 +41,11 @@
 ./init.ps1
 Set-Location demo
 python main.py
+
+# 本机录像 Go 回归（需本机 ONNX Runtime DLL、FFmpeg 与已锁定 ONNX 工件）
+Set-Location ..\v2
+$env:CGO_ENABLED='1'
+go run ./cmd/regression --help
 ```
 
 ## 已知事实和限制
diff --git a/progress.md b/progress.md
index b5e63fc..af6bc0f 100644
--- a/progress.md
+++ b/progress.md
@@ -487,3 +487,12 @@
 - 阻塞：无代码阻塞。任务验收将明确区分“提交的合成契约回归 / 本机 demo 无报警回放”与“需本机正例录像才能证实的录像级确认事件、延迟”。
 - 决策：不复制或提交客户录像；先忠实复现 V1 的纯领域合约，并让回归工具接收外部本机录像和基线 JSON。
 - 下一步：先为 Go Pose 后处理与事件状态机编写失败测试。
+
+## 【2026-07-22】T-303 实现与无报警录像回归（部分完成）
+
+- 状态：PARTIAL（代码与无报警回归完成；真实正例录像回归待本机素材）
+- 变更：新增 `v2/internal/pose`（114 补边、双线性缩放后 uint8 量化、BGR→RGB/CHW、YOLOv8 Pose NMS、17 点与坐标还原）、`v2/internal/fall`（归一化中心点跟踪、姿态质量/几何证据、倒地策略、四态状态机、事件 ID）和 `v2/cmd/regression`（FFmpeg 回放→ONNX Pose→事件引擎）。`spike` 的预处理现委托给同一正式实现，ONNX Runtime session 可跨帧复用。
+- 验证：Go 单元测试覆盖 letterbox 补边/通道布局、NMS 坐标还原、输入长度、事件确认、缺帧中断和持续站立不报警；`CGO_ENABLED=1 go test ./...` 通过。本机 317 帧回放：V1 为 253 个有人帧、263 人次、0 个 CONFIRMED；Go 为 255 个有人帧、265 人次、0 个 CONFIRMED。二者无报警结论一致。合成正例以同一 V1 策略/状态机合约在 1.81 秒生成一个 CONFIRMED，Go 测试同样通过。
+- 阻塞：无客户或正例录像被提交；仓库也没有经同意的正例回放素材。因此不能把合成契约或无报警录像表述为真实正例的 Go/V1 等价，也不能把 T-303 标为 DONE。
+- 决策：保持 T-303 为 DOING；回归命令接受本机路径，不把录像、截图、事件 JSONL、RTSP 地址或凭证写进仓库。解码器差异造成同一无报警录像的人次计数轻微差异，事件而非逐帧检测人次是当前验收基线。
+- 下一步：提供或指定一段经同意、无敏感信息的本机正例录像及其 V1 输出后，运行同一命令比对确认事件与 1–3 秒延迟；通过后才可完成 T-303，继而领取 T-304。
diff --git a/v2/cmd/regression/main.go b/v2/cmd/regression/main.go
new file mode 100644
index 0000000..634bfaa
--- /dev/null
+++ b/v2/cmd/regression/main.go
@@ -0,0 +1,118 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"time"
+
+	"silverpose/v2/internal/fall"
+	"silverpose/v2/internal/pose"
+	"silverpose/v2/internal/spike"
+)
+
+func main() {
+	ffmpegPath := flag.String("ffmpeg", "ffmpeg", "path to ffmpeg.exe")
+	videoPath := flag.String("video", "..\\demo\\1.mp4", "local non-sensitive validation video")
+	width := flag.Int("width", 848, "source video frame width")
+	height := flag.Int("height", 480, "source video frame height")
+	fps := flag.Float64("fps", 30, "replay timestamp frames per second")
+	maxFrames := flag.Int("max-frames", 0, "maximum frames to process; zero reads the complete video")
+	modelPath := flag.String("onnx", "assets\\best.onnx", "locked ONNX pose model path")
+	runtimeDLLPath := flag.String("ort-dll", "", "absolute onnxruntime.dll path")
+	flag.Parse()
+
+	if *runtimeDLLPath == "" || *width <= 0 || *height <= 0 || *fps <= 0 || *maxFrames < 0 {
+		fail("--ort-dll is required; width, height and fps must be positive; max-frames cannot be negative")
+	}
+	engine, err := fall.NewEngine(fall.EngineConfig{
+		KeypointConfidenceThreshold:     0.4,
+		SuspectWindowSeconds:            0.5,
+		ConfirmWindowSeconds:            1.8,
+		RecoveryWindowSeconds:           2.0,
+		CooldownSeconds:                 10.0,
+		RequireRapidDrop:                false,
+		RequireLowerBody:                false,
+		HorizontalAngleThresholdDegrees: 45.0,
+		ConfigVersion:                   "v1-default-20260722",
+		SessionID:                       "video-regression",
+	})
+	if err != nil {
+		fail("create event engine: %v", err)
+	}
+	runtime, err := spike.OpenRuntime(*modelPath, *runtimeDLLPath)
+	if err != nil {
+		fail("open ONNX Pose runtime: %v", err)
+	}
+	defer runtime.Close()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
+	defer cancel()
+	command := exec.CommandContext(ctx, *ffmpegPath, "-v", "error", "-i", *videoPath, "-f", "rawvideo", "-pix_fmt", "bgr24", "-")
+	stdout, err := command.StdoutPipe()
+	if err != nil {
+		fail("open FFmpeg output: %v", err)
+	}
+	if err := command.Start(); err != nil {
+		fail("start FFmpeg: %v", err)
+	}
+
+	frameBytes := *width * *height * 3
+	frame := make([]byte, frameBytes)
+	frameCount := 0
+	personFrames := 0
+	personCount := 0
+	events := make([]fall.Event, 0)
+	limited := false
+	for *maxFrames == 0 || frameCount < *maxFrames {
+		_, err := io.ReadFull(stdout, frame)
+		if errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF) {
+			break
+		}
+		if err != nil {
+			fail("read FFmpeg BGR frame: %v", err)
+		}
+		input, transform, err := pose.PreprocessBGR(frame, *width, *height, 640)
+		if err != nil {
+			fail("preprocess frame %d: %v", frameCount, err)
+		}
+		output, err := runtime.Run(input)
+		if err != nil {
+			fail("run ONNX Pose for frame %d: %v", frameCount, err)
+		}
+		people, err := pose.ParseYOLOv8Pose(output, transform, 0.25, 0.70)
+		if err != nil {
+			fail("parse ONNX Pose for frame %d: %v", frameCount, err)
+		}
+		result := engine.Process(fall.Frame{Timestamp: float64(frameCount) / *fps, Width: *width, Height: *height, Poses: people})
+		if len(people) > 0 {
+			personFrames++
+			personCount += len(people)
+		}
+		events = append(events, result.Events...)
+		frameCount++
+	}
+	if *maxFrames > 0 && frameCount == *maxFrames {
+		limited = true
+		cancel()
+	}
+	if err := command.Wait(); err != nil {
+		if !limited {
+			fail("FFmpeg ended with an error: %v", err)
+		}
+	}
+
+	fmt.Printf("REGRESSION_OK frames=%d person_frames=%d people=%d events=%d\n", frameCount, personFrames, personCount, len(events))
+	for _, event := range events {
+		fmt.Printf("EVENT id=%s track=%s latency=%.6f state=%s\n", event.EventID, event.TrackID, event.LatencySeconds, event.State)
+	}
+}
+
+func fail(format string, args ...any) {
+	fmt.Fprintf(os.Stderr, "regression: "+format+"\n", args...)
+	os.Exit(1)
+}
diff --git a/v2/cmd/spike/main.go b/v2/cmd/spike/main.go
index b327a47..69e2dbe 100644
--- a/v2/cmd/spike/main.go
+++ b/v2/cmd/spike/main.go
@@ -8,6 +8,7 @@ import (
 	"os/exec"
 	"time"
 
+	"silverpose/v2/internal/pose"
 	"silverpose/v2/internal/spike"
 )
 
@@ -41,7 +42,7 @@ func main() {
 		fail("decoded BGR frame has %d bytes, want %d; verify --width/--height", len(raw), expectedBytes)
 	}
 
-	input, err := spike.LetterboxBGRToNCHW(raw, *width, *height, 640)
+	input, transform, err := pose.PreprocessBGR(raw, *width, *height, 640)
 	if err != nil {
 		fail("preprocess frame: %v", err)
 	}
@@ -49,6 +50,10 @@ func main() {
 	if err != nil {
 		fail("run ONNX Pose: %v", err)
 	}
+	people, err := pose.ParseYOLOv8Pose(output, transform, 0.25, 0.70)
+	if err != nil {
+		fail("parse ONNX Pose: %v", err)
+	}
 
 	max := float32(0)
 	for _, value := range output {
@@ -56,7 +61,10 @@ func main() {
 			max = value
 		}
 	}
-	fmt.Printf("SPIKE_OK frame=%dx%d input=%d output=%d max=%.4f\n", *width, *height, len(input), len(output), max)
+	fmt.Printf("SPIKE_OK frame=%dx%d input=%d output=%d people=%d max=%.4f\n", *width, *height, len(input), len(output), len(people), max)
+	for index, person := range people {
+		fmt.Printf("PERSON index=%d conf=%.6f box=%.3f,%.3f,%.3f,%.3f\n", index, person.Confidence, person.Box.Left, person.Box.Top, person.Box.Right, person.Box.Bottom)
+	}
 }
 
 func fail(format string, args ...any) {
diff --git a/v2/internal/fall/evidence.go b/v2/internal/fall/evidence.go
new file mode 100644
index 0000000..474930a
--- /dev/null
+++ b/v2/internal/fall/evidence.go
@@ -0,0 +1,62 @@
+package fall
+
+import (
+	"math"
+
+	"silverpose/v2/internal/pose"
+)
+
+var torsoJoints = [...]int{5, 6, 11, 12}
+var lowerJoints = [...]int{13, 14, 15, 16}
+
+func assessPoseQuality(person pose.PersonPose, threshold float32, requireLowerBody bool) PoseQuality {
+	if threshold < 0 || threshold > 1 {
+		return PoseQuality{Reason: "invalid_threshold"}
+	}
+	visible := 0
+	for _, keypoint := range person.Keypoints {
+		if keypoint.Confidence >= threshold {
+			visible++
+		}
+	}
+	for _, index := range torsoJoints {
+		if person.Keypoints[index].Confidence < threshold {
+			return PoseQuality{Reason: "required_joint_low_confidence", VisibleJointCount: visible}
+		}
+	}
+	if requireLowerBody {
+		for _, index := range lowerJoints {
+			if person.Keypoints[index].Confidence < threshold {
+				return PoseQuality{Reason: "required_joint_low_confidence", VisibleJointCount: visible}
+			}
+		}
+	}
+	return PoseQuality{Accepted: true, Reason: "accepted", VisibleJointCount: visible}
+}
+
+func extractEvidence(person pose.PersonPose, quality PoseQuality, previous *PoseEvidence, horizontalAngleThreshold float32) PoseEvidence {
+	if !quality.Accepted {
+		return PoseEvidence{Reason: quality.Reason}
+	}
+	shoulderX, shoulderY := midpoint(person, 5, 6)
+	hipX, hipY := midpoint(person, 11, 12)
+	vectorX := hipX - shoulderX
+	vectorY := hipY - shoulderY
+	torsoLength := float32(math.Hypot(float64(vectorX), float64(vectorY)))
+	if torsoLength == 0 {
+		return PoseEvidence{HipCenterY: hipY, HasHipCenterY: true, TorsoLength: 0, Reason: "degenerate_torso"}
+	}
+	cosine := math.Max(-1, math.Min(1, math.Abs(float64(vectorX))/float64(torsoLength)))
+	angle := float32(math.Acos(cosine) * 180 / math.Pi)
+	rapid := previous != nil && previous.Accepted && previous.HasHipCenterY && hipY-previous.HipCenterY >= 0.5*torsoLength
+	return PoseEvidence{
+		Accepted: true, HorizontalPose: angle <= horizontalAngleThreshold,
+		RapidVerticalChange: rapid, HorizontalAngleDegree: angle, HasAngle: true,
+		HipCenterY: hipY, HasHipCenterY: true, TorsoLength: torsoLength, Reason: "accepted",
+	}
+}
+
+func midpoint(person pose.PersonPose, first, second int) (float32, float32) {
+	return (person.Keypoints[first].X + person.Keypoints[second].X) / 2,
+		(person.Keypoints[first].Y + person.Keypoints[second].Y) / 2
+}
diff --git a/v2/internal/fall/pipeline.go b/v2/internal/fall/pipeline.go
new file mode 100644
index 0000000..850c500
--- /dev/null
+++ b/v2/internal/fall/pipeline.go
@@ -0,0 +1,94 @@
+package fall
+
+import "fmt"
+
+type Engine struct {
+	config           EngineConfig
+	tracker          *tracker
+	policy           *policy
+	stateMachine     *stateMachine
+	previousEvidence map[string]PoseEvidence
+	activeTrackIDs   map[string]bool
+}
+
+func NewEngine(config EngineConfig) (*Engine, error) {
+	if config.KeypointConfidenceThreshold < 0 || config.KeypointConfidenceThreshold > 1 {
+		return nil, fmt.Errorf("keypoint confidence threshold must be between 0 and 1")
+	}
+	if config.SuspectWindowSeconds < 0 {
+		return nil, fmt.Errorf("suspect window seconds must be non-negative")
+	}
+	if config.HorizontalAngleThresholdDegrees < 0 || config.HorizontalAngleThresholdDegrees > 90 {
+		return nil, fmt.Errorf("horizontal angle threshold degrees must be between 0 and 90")
+	}
+	tracker, err := newTracker(0.2, 2.0)
+	if err != nil {
+		return nil, err
+	}
+	stateMachine, err := newStateMachine(config)
+	if err != nil {
+		return nil, err
+	}
+	return &Engine{
+		config: config, tracker: tracker, policy: newPolicy(config.SuspectWindowSeconds, config.RequireRapidDrop),
+		stateMachine: stateMachine, previousEvidence: make(map[string]PoseEvidence), activeTrackIDs: make(map[string]bool),
+	}, nil
+}
+
+func (engine *Engine) StateOf(trackID string) State {
+	return engine.stateMachine.stateOf(trackID)
+}
+
+func (engine *Engine) Process(frame Frame) FrameResult {
+	tracked, err := engine.tracker.update(frame.Poses, frame.Timestamp, frame.Width, frame.Height)
+	if err != nil {
+		return FrameResult{}
+	}
+	currentIDs := make(map[string]bool, len(tracked))
+	for _, trackedPose := range tracked {
+		currentIDs[trackedPose.TrackID] = true
+	}
+	events := engine.rejectMissingTracks(currentIDs, frame.Timestamp)
+	people := make([]PersonAnalysis, 0, len(tracked))
+	for _, trackedPose := range tracked {
+		quality := assessPoseQuality(trackedPose.Pose, engine.config.KeypointConfidenceThreshold, engine.config.RequireLowerBody)
+		var previous *PoseEvidence
+		if candidate, found := engine.previousEvidence[trackedPose.TrackID]; found {
+			previous = &candidate
+		}
+		poseEvidence := extractEvidence(trackedPose.Pose, quality, previous, engine.config.HorizontalAngleThresholdDegrees)
+		stateBefore := engine.stateMachine.stateOf(trackedPose.TrackID)
+		evidence := engine.policy.evaluate(trackedPose.TrackID, poseEvidence, frame.Timestamp, stateBefore)
+		newEvents, err := engine.stateMachine.update(trackedPose.TrackID, evidence, frame.Timestamp)
+		if err == nil {
+			events = append(events, newEvents...)
+		}
+		if poseEvidence.Accepted {
+			engine.previousEvidence[trackedPose.TrackID] = poseEvidence
+		} else {
+			delete(engine.previousEvidence, trackedPose.TrackID)
+		}
+		people = append(people, PersonAnalysis{
+			TrackedPose: trackedPose, PoseEvidence: poseEvidence, Evidence: evidence,
+			State: engine.stateMachine.stateOf(trackedPose.TrackID),
+		})
+	}
+	engine.activeTrackIDs = currentIDs
+	return FrameResult{People: people, Events: events}
+}
+
+func (engine *Engine) rejectMissingTracks(currentIDs map[string]bool, now float64) []Event {
+	events := make([]Event, 0)
+	for trackID := range engine.activeTrackIDs {
+		if currentIDs[trackID] {
+			continue
+		}
+		delete(engine.previousEvidence, trackID)
+		engine.policy.evaluate(trackID, PoseEvidence{}, now, engine.stateMachine.stateOf(trackID))
+		newEvents, err := engine.stateMachine.update(trackID, Evidence{}, now)
+		if err == nil {
+			events = append(events, newEvents...)
+		}
+	}
+	return events
+}
diff --git a/v2/internal/fall/pipeline_test.go b/v2/internal/fall/pipeline_test.go
new file mode 100644
index 0000000..91981c3
--- /dev/null
+++ b/v2/internal/fall/pipeline_test.go
@@ -0,0 +1,105 @@
+package fall
+
+import (
+	"math"
+	"testing"
+
+	"silverpose/v2/internal/pose"
+)
+
+func TestEngineConfirmsPersistentHorizontalPoseAtV1Delay(t *testing.T) {
+	engine, err := NewEngine(EngineConfig{
+		KeypointConfidenceThreshold:     0.4,
+		SuspectWindowSeconds:            0.5,
+		ConfirmWindowSeconds:            1.8,
+		RecoveryWindowSeconds:           2.0,
+		CooldownSeconds:                 10.0,
+		RequireRapidDrop:                false,
+		RequireLowerBody:                false,
+		HorizontalAngleThresholdDegrees: 45.0,
+		ConfigVersion:                   "cfg-v1-contract",
+		SessionID:                       "regression",
+	})
+	if err != nil {
+		t.Fatalf("NewEngine returned an error: %v", err)
+	}
+
+	engine.Process(Frame{Timestamp: 0.0, Width: 180, Height: 180, Poses: []pose.PersonPose{testPose(false)}})
+	engine.Process(Frame{Timestamp: 0.1, Width: 180, Height: 180, Poses: []pose.PersonPose{testPose(true)}})
+	result := engine.Process(Frame{Timestamp: 1.91, Width: 180, Height: 180, Poses: []pose.PersonPose{testPose(true)}})
+
+	if len(result.Events) != 1 {
+		t.Fatalf("events = %+v, want one confirmation", result.Events)
+	}
+	event := result.Events[0]
+	if event.TrackID != "P-0001" || math.Abs(event.LatencySeconds-1.81) > 1e-9 || event.ConfigVersion != "cfg-v1-contract" {
+		t.Fatalf("event = %+v", event)
+	}
+	if got := engine.StateOf("P-0001"); got != Confirmed {
+		t.Fatalf("state = %s, want CONFIRMED", got)
+	}
+}
+
+func TestEngineDoesNotConfirmWhenTrackIsMissing(t *testing.T) {
+	engine, err := NewEngine(testConfig())
+	if err != nil {
+		t.Fatalf("NewEngine returned an error: %v", err)
+	}
+
+	engine.Process(Frame{Timestamp: 0.0, Width: 180, Height: 180, Poses: []pose.PersonPose{testPose(false)}})
+	engine.Process(Frame{Timestamp: 0.1, Width: 180, Height: 180, Poses: []pose.PersonPose{testPose(true)}})
+	engine.Process(Frame{Timestamp: 0.2, Width: 180, Height: 180})
+	result := engine.Process(Frame{Timestamp: 1.9, Width: 180, Height: 180, Poses: []pose.PersonPose{testPose(true)}})
+
+	if len(result.Events) != 0 {
+		t.Fatalf("events = %+v, want none after a missing track", result.Events)
+	}
+}
+
+func TestEngineDoesNotAlarmForUprightSequence(t *testing.T) {
+	engine, err := NewEngine(testConfig())
+	if err != nil {
+		t.Fatalf("NewEngine returned an error: %v", err)
+	}
+
+	for _, timestamp := range []float64{0.0, 0.6, 1.2, 1.8, 2.4} {
+		result := engine.Process(Frame{Timestamp: timestamp, Width: 180, Height: 180, Poses: []pose.PersonPose{testPose(false)}})
+		if len(result.Events) != 0 {
+			t.Fatalf("timestamp %v emitted %+v for upright pose", timestamp, result.Events)
+		}
+	}
+}
+
+func testConfig() EngineConfig {
+	return EngineConfig{
+		KeypointConfidenceThreshold:     0.4,
+		SuspectWindowSeconds:            0.5,
+		ConfirmWindowSeconds:            1.8,
+		RecoveryWindowSeconds:           2.0,
+		CooldownSeconds:                 10.0,
+		RequireRapidDrop:                false,
+		RequireLowerBody:                false,
+		HorizontalAngleThresholdDegrees: 45.0,
+		ConfigVersion:                   "cfg-v1-contract",
+		SessionID:                       "regression",
+	}
+}
+
+func testPose(horizontal bool) pose.PersonPose {
+	person := pose.PersonPose{Box: pose.Box{Left: 20, Top: 20, Right: 160, Bottom: 160}, Confidence: 0.9}
+	for index := range person.Keypoints {
+		person.Keypoints[index] = pose.Keypoint{X: float32(index), Y: float32(index), Confidence: 0.9}
+	}
+	if horizontal {
+		person.Keypoints[5] = pose.Keypoint{X: 20, Y: 80, Confidence: 0.9}
+		person.Keypoints[6] = pose.Keypoint{X: 30, Y: 80, Confidence: 0.9}
+		person.Keypoints[11] = pose.Keypoint{X: 70, Y: 100, Confidence: 0.9}
+		person.Keypoints[12] = pose.Keypoint{X: 80, Y: 100, Confidence: 0.9}
+	} else {
+		person.Keypoints[5] = pose.Keypoint{X: 30, Y: 10, Confidence: 0.9}
+		person.Keypoints[6] = pose.Keypoint{X: 40, Y: 10, Confidence: 0.9}
+		person.Keypoints[11] = pose.Keypoint{X: 30, Y: 30, Confidence: 0.9}
+		person.Keypoints[12] = pose.Keypoint{X: 40, Y: 30, Confidence: 0.9}
+	}
+	return person
+}
diff --git a/v2/internal/fall/policy.go b/v2/internal/fall/policy.go
new file mode 100644
index 0000000..b2240f9
--- /dev/null
+++ b/v2/internal/fall/policy.go
@@ -0,0 +1,37 @@
+package fall
+
+type policy struct {
+	suspectWindowSeconds float64
+	requireRapidDrop     bool
+	rapidDropAt          map[string]float64
+}
+
+func newPolicy(suspectWindowSeconds float64, requireRapidDrop bool) *policy {
+	return &policy{
+		suspectWindowSeconds: suspectWindowSeconds,
+		requireRapidDrop:     requireRapidDrop,
+		rapidDropAt:          make(map[string]float64),
+	}
+}
+
+func (policy *policy) evaluate(trackID string, poseEvidence PoseEvidence, now float64, state State) Evidence {
+	if !poseEvidence.Accepted {
+		delete(policy.rapidDropAt, trackID)
+		return Evidence{}
+	}
+	if poseEvidence.RapidVerticalChange {
+		policy.rapidDropAt[trackID] = now
+	}
+	candidate := false
+	if state == Suspect {
+		candidate = poseEvidence.HorizontalPose
+	} else if poseEvidence.HorizontalPose {
+		if !policy.requireRapidDrop {
+			candidate = true
+		} else if droppedAt, found := policy.rapidDropAt[trackID]; found {
+			candidate = now-droppedAt <= policy.suspectWindowSeconds
+		}
+	}
+	recovery := (state == Confirmed || state == Recovering) && !poseEvidence.HorizontalPose && !poseEvidence.RapidVerticalChange
+	return Evidence{Accepted: true, IsFallCandidate: candidate, IsRecoveryCandidate: recovery}
+}
diff --git a/v2/internal/fall/state.go b/v2/internal/fall/state.go
new file mode 100644
index 0000000..160d725
--- /dev/null
+++ b/v2/internal/fall/state.go
@@ -0,0 +1,142 @@
+package fall
+
+import "fmt"
+
+type stateRecord struct {
+	state State
+
+	suspectStartedAt     float64
+	hasSuspectStartedAt  bool
+	confirmedAt          float64
+	hasConfirmedAt       bool
+	recoveryStartedAt    float64
+	hasRecoveryStartedAt bool
+	lastUpdatedAt        float64
+	hasLastUpdatedAt     bool
+}
+
+type stateMachine struct {
+	confirmWindowSeconds  float64
+	recoveryWindowSeconds float64
+	cooldownSeconds       float64
+	configVersion         string
+	sessionID             string
+	records               map[string]*stateRecord
+	nextEventNumber       int
+}
+
+func newStateMachine(config EngineConfig) (*stateMachine, error) {
+	if config.ConfirmWindowSeconds < 1 || config.ConfirmWindowSeconds > 3 {
+		return nil, fmt.Errorf("confirm window seconds must be between 1 and 3")
+	}
+	if config.RecoveryWindowSeconds <= 0 {
+		return nil, fmt.Errorf("recovery window seconds must be positive")
+	}
+	if config.CooldownSeconds < 0 {
+		return nil, fmt.Errorf("cooldown seconds must be non-negative")
+	}
+	if config.ConfigVersion == "" {
+		return nil, fmt.Errorf("config version must be non-empty")
+	}
+	return &stateMachine{
+		confirmWindowSeconds: config.ConfirmWindowSeconds, recoveryWindowSeconds: config.RecoveryWindowSeconds,
+		cooldownSeconds: config.CooldownSeconds, configVersion: config.ConfigVersion, sessionID: config.SessionID,
+		records: make(map[string]*stateRecord), nextEventNumber: 1,
+	}, nil
+}
+
+func (machine *stateMachine) stateOf(trackID string) State {
+	if record, found := machine.records[trackID]; found {
+		return record.state
+	}
+	return Normal
+}
+
+func (machine *stateMachine) update(trackID string, evidence Evidence, now float64) ([]Event, error) {
+	if trackID == "" {
+		return nil, fmt.Errorf("track ID must be non-empty")
+	}
+	record, found := machine.records[trackID]
+	if !found {
+		record = &stateRecord{state: Normal}
+		machine.records[trackID] = record
+	}
+	if record.hasLastUpdatedAt && now < record.lastUpdatedAt {
+		return nil, fmt.Errorf("timestamps must be monotonic per track")
+	}
+	record.lastUpdatedAt, record.hasLastUpdatedAt = now, true
+
+	if !evidence.Accepted {
+		machine.rejectEvidence(record)
+		return nil, nil
+	}
+	switch record.state {
+	case Normal:
+		if evidence.IsFallCandidate {
+			record.state, record.suspectStartedAt, record.hasSuspectStartedAt = Suspect, now, true
+		}
+		return nil, nil
+	case Suspect:
+		if !evidence.IsFallCandidate {
+			machine.setNormal(record)
+			return nil, nil
+		}
+		if now-record.suspectStartedAt >= machine.confirmWindowSeconds {
+			record.state, record.confirmedAt, record.hasConfirmedAt = Confirmed, now, true
+			event := machine.newEvent(trackID, record.suspectStartedAt, now)
+			record.hasSuspectStartedAt = false
+			return []Event{event}, nil
+		}
+		return nil, nil
+	case Confirmed:
+		if evidence.IsRecoveryCandidate && now-record.confirmedAt >= machine.cooldownSeconds {
+			record.state, record.recoveryStartedAt, record.hasRecoveryStartedAt = Recovering, now, true
+		}
+		return nil, nil
+	case Recovering:
+		if evidence.IsFallCandidate {
+			record.state, record.suspectStartedAt, record.hasSuspectStartedAt = Suspect, now, true
+			record.hasRecoveryStartedAt = false
+			return nil, nil
+		}
+		if !evidence.IsRecoveryCandidate {
+			record.state, record.hasRecoveryStartedAt = Confirmed, false
+			return nil, nil
+		}
+		if now-record.recoveryStartedAt >= machine.recoveryWindowSeconds {
+			machine.setNormal(record)
+		}
+		return nil, nil
+	default:
+		return nil, fmt.Errorf("unknown fall state")
+	}
+}
+
+func (machine *stateMachine) rejectEvidence(record *stateRecord) {
+	if record.state == Suspect {
+		machine.setNormal(record)
+	} else if record.state == Recovering {
+		record.state, record.hasRecoveryStartedAt = Confirmed, false
+	}
+}
+
+func (machine *stateMachine) setNormal(record *stateRecord) {
+	record.state = Normal
+	record.hasSuspectStartedAt = false
+	record.hasConfirmedAt = false
+	record.hasRecoveryStartedAt = false
+}
+
+func (machine *stateMachine) newEvent(trackID string, suspectedAt, confirmedAt float64) Event {
+	prefix := "FALL-"
+	if machine.sessionID != "" {
+		prefix += machine.sessionID + "-"
+	}
+	event := Event{
+		EventID: fmt.Sprintf("%s%06d", prefix, machine.nextEventNumber), TrackID: trackID,
+		ConfigVersion: machine.configVersion, SuspectedAtMonotonic: suspectedAt,
+		ConfirmedAtMonotonic: confirmedAt, LatencySeconds: confirmedAt - suspectedAt, State: Confirmed,
+	}
+	machine.nextEventNumber++
+	return event
+}
diff --git a/v2/internal/fall/tracker.go b/v2/internal/fall/tracker.go
new file mode 100644
index 0000000..73fdb4e
--- /dev/null
+++ b/v2/internal/fall/tracker.go
@@ -0,0 +1,93 @@
+package fall
+
+import (
+	"fmt"
+	"math"
+	"sort"
+
+	"silverpose/v2/internal/pose"
+)
+
+type track struct {
+	centerX    float32
+	centerY    float32
+	lastSeenAt float64
+}
+
+type tracker struct {
+	maxMatchDistanceRatio float64
+	maxAgeSeconds         float64
+	tracks                map[string]track
+	nextTrackNumber       int
+}
+
+func newTracker(maxMatchDistanceRatio, maxAgeSeconds float64) (*tracker, error) {
+	if maxMatchDistanceRatio <= 0 || maxMatchDistanceRatio > 1 {
+		return nil, fmt.Errorf("max match distance ratio must be in (0, 1]")
+	}
+	if maxAgeSeconds <= 0 {
+		return nil, fmt.Errorf("max age seconds must be positive")
+	}
+	return &tracker{
+		maxMatchDistanceRatio: maxMatchDistanceRatio,
+		maxAgeSeconds:         maxAgeSeconds,
+		tracks:                make(map[string]track),
+		nextTrackNumber:       1,
+	}, nil
+}
+
+func (tracker *tracker) update(poses []pose.PersonPose, now float64, width, height int) ([]TrackedPose, error) {
+	if width <= 0 || height <= 0 {
+		return nil, fmt.Errorf("frame size must contain positive width and height")
+	}
+	tracker.expire(now)
+	availableIDs := make(map[string]bool, len(tracker.tracks))
+	for trackID := range tracker.tracks {
+		availableIDs[trackID] = true
+	}
+	tracked := make([]TrackedPose, 0, len(poses))
+	for _, person := range poses {
+		centerX := (person.Box.Left + person.Box.Right) / 2
+		centerY := (person.Box.Top + person.Box.Bottom) / 2
+		trackID := tracker.nearestAvailable(centerX, centerY, availableIDs, width, height)
+		if trackID == "" {
+			trackID = fmt.Sprintf("P-%04d", tracker.nextTrackNumber)
+			tracker.nextTrackNumber++
+		} else {
+			delete(availableIDs, trackID)
+		}
+		tracker.tracks[trackID] = track{centerX: centerX, centerY: centerY, lastSeenAt: now}
+		tracked = append(tracked, TrackedPose{TrackID: trackID, Pose: person})
+	}
+	return tracked, nil
+}
+
+func (tracker *tracker) nearestAvailable(centerX, centerY float32, availableIDs map[string]bool, width, height int) string {
+	ids := make([]string, 0, len(availableIDs))
+	for trackID := range availableIDs {
+		ids = append(ids, trackID)
+	}
+	sort.Strings(ids)
+	closestID := ""
+	closestDistance := math.Inf(1)
+	for _, trackID := range ids {
+		previous := tracker.tracks[trackID]
+		distance := math.Hypot(
+			float64(centerX-previous.centerX)/float64(width),
+			float64(centerY-previous.centerY)/float64(height),
+		)
+		if distance <= tracker.maxMatchDistanceRatio && distance < closestDistance {
+			closestID = trackID
+			closestDistance = distance
+		}
+	}
+	return closestID
+}
+
+func (tracker *tracker) expire(now float64) {
+	for trackID, current := range tracker.tracks {
+		if now-current.lastSeenAt > tracker.maxAgeSeconds {
+			delete(tracker.tracks, trackID)
+		}
+	}
+}
diff --git a/v2/internal/fall/types.go b/v2/internal/fall/types.go
new file mode 100644
index 0000000..7d4ec5f
--- /dev/null
+++ b/v2/internal/fall/types.go
@@ -0,0 +1,83 @@
+package fall
+
+import "silverpose/v2/internal/pose"
+
+type State string
+
+const (
+	Normal     State = "NORMAL"
+	Suspect    State = "SUSPECT"
+	Confirmed  State = "CONFIRMED"
+	Recovering State = "RECOVERING"
+)
+
+type Evidence struct {
+	Accepted            bool
+	IsFallCandidate     bool
+	IsRecoveryCandidate bool
+}
+
+type PoseQuality struct {
+	Accepted          bool
+	Reason            string
+	VisibleJointCount int
+}
+
+type PoseEvidence struct {
+	Accepted              bool
+	HorizontalPose        bool
+	RapidVerticalChange   bool
+	HorizontalAngleDegree float32
+	HasAngle              bool
+	HipCenterY            float32
+	HasHipCenterY         bool
+	TorsoLength           float32
+	Reason                string
+}
+
+type Event struct {
+	EventID              string
+	TrackID              string
+	ConfigVersion        string
+	SuspectedAtMonotonic float64
+	ConfirmedAtMonotonic float64
+	LatencySeconds       float64
+	State                State
+}
+
+type Frame struct {
+	Timestamp float64
+	Width     int
+	Height    int
+	Poses     []pose.PersonPose
+}
+
+type TrackedPose struct {
+	TrackID string
+	Pose    pose.PersonPose
+}
+
+type PersonAnalysis struct {
+	TrackedPose  TrackedPose
+	PoseEvidence PoseEvidence
+	Evidence     Evidence
+	State        State
+}
+
+type FrameResult struct {
+	People []PersonAnalysis
+	Events []Event
+}
+
+type EngineConfig struct {
+	KeypointConfidenceThreshold     float32
+	SuspectWindowSeconds            float64
+	ConfirmWindowSeconds            float64
+	RecoveryWindowSeconds           float64
+	CooldownSeconds                 float64
+	RequireRapidDrop                bool
+	RequireLowerBody                bool
+	HorizontalAngleThresholdDegrees float32
+	ConfigVersion                   string
+	SessionID                       string
+}
diff --git a/v2/internal/pose/postprocess.go b/v2/internal/pose/postprocess.go
new file mode 100644
index 0000000..c306762
--- /dev/null
+++ b/v2/internal/pose/postprocess.go
@@ -0,0 +1,125 @@
+package pose
+
+import (
+	"fmt"
+	"sort"
+)
+
+// ParseYOLOv8Pose turns the fixed [1,56,8400] YOLO Pose output into source
+// pixel coordinates, applying confidence filtering and class-agnostic NMS.
+func ParseYOLOv8Pose(output []float32, transform LetterboxTransform, confidenceThreshold, iouThreshold float32) ([]PersonPose, error) {
+	if len(output) != YOLOPoseOutputValues {
+		return nil, fmt.Errorf("YOLO Pose output length = %d, want %d", len(output), YOLOPoseOutputValues)
+	}
+	if transform.Scale <= 0 {
+		return nil, fmt.Errorf("letterbox scale must be positive")
+	}
+	if confidenceThreshold < 0 || confidenceThreshold > 1 || iouThreshold < 0 || iouThreshold > 1 {
+		return nil, fmt.Errorf("confidence and IoU thresholds must be between 0 and 1")
+	}
+
+	candidates := make([]PersonPose, 0)
+	for candidate := 0; candidate < YOLOPoseCandidateCount; candidate++ {
+		confidence := valueAt(output, 4, candidate)
+		if confidence < confidenceThreshold {
+			continue
+		}
+		centerX := valueAt(output, 0, candidate)
+		centerY := valueAt(output, 1, candidate)
+		width := valueAt(output, 2, candidate)
+		height := valueAt(output, 3, candidate)
+		person := PersonPose{
+			Box: Box{
+				Left:   transform.restoreX(centerX - width/2),
+				Top:    transform.restoreY(centerY - height/2),
+				Right:  transform.restoreX(centerX + width/2),
+				Bottom: transform.restoreY(centerY + height/2),
+			},
+			Confidence: confidence,
+		}
+		for keypoint := 0; keypoint < YOLOPoseKeypointCount; keypoint++ {
+			channel := 5 + keypoint*3
+			person.Keypoints[keypoint] = Keypoint{
+				X:          transform.restoreX(valueAt(output, channel, candidate)),
+				Y:          transform.restoreY(valueAt(output, channel+1, candidate)),
+				Confidence: valueAt(output, channel+2, candidate),
+			}
+		}
+		candidates = append(candidates, person)
+	}
+
+	sort.SliceStable(candidates, func(left, right int) bool {
+		return candidates[left].Confidence > candidates[right].Confidence
+	})
+	selected := make([]PersonPose, 0, len(candidates))
+	for _, candidate := range candidates {
+		overlaps := false
+		for _, accepted := range selected {
+			if intersectionOverUnion(candidate.Box, accepted.Box) > iouThreshold {
+				overlaps = true
+				break
+			}
+		}
+		if !overlaps {
+			selected = append(selected, candidate)
+		}
+	}
+	return selected, nil
+}
+
+func valueAt(output []float32, channel, candidate int) float32 {
+	return output[channel*YOLOPoseCandidateCount+candidate]
+}
+
+func (transform LetterboxTransform) restoreX(value float32) float32 {
+	return clampCoordinate((value-float32(transform.PadLeft))/transform.Scale, transform.OriginalWidth)
+}
+
+func (transform LetterboxTransform) restoreY(value float32) float32 {
+	return clampCoordinate((value-float32(transform.PadTop))/transform.Scale, transform.OriginalHeight)
+}
+
+func clampCoordinate(value float32, size int) float32 {
+	if size <= 0 {
+		return value
+	}
+	if value < 0 {
+		return 0
+	}
+	maximum := float32(size)
+	if value > maximum {
+		return maximum
+	}
+	return value
+}
+
+func intersectionOverUnion(left, right Box) float32 {
+	intersectionLeft := maxFloat(left.Left, right.Left)
+	intersectionTop := maxFloat(left.Top, right.Top)
+	intersectionRight := minFloat(left.Right, right.Right)
+	intersectionBottom := minFloat(left.Bottom, right.Bottom)
+	intersectionWidth := maxFloat(0, intersectionRight-intersectionLeft)
+	intersectionHeight := maxFloat(0, intersectionBottom-intersectionTop)
+	intersection := intersectionWidth * intersectionHeight
+	leftArea := maxFloat(0, left.Right-left.Left) * maxFloat(0, left.Bottom-left.Top)
+	rightArea := maxFloat(0, right.Right-right.Left) * maxFloat(0, right.Bottom-right.Top)
+	union := leftArea + rightArea - intersection
+	if union <= 0 {
+		return 0
+	}
+	return intersection / union
+}
+
+func minFloat(left, right float32) float32 {
+	if left < right {
+		return left
+	}
+	return right
+}
+
+func maxFloat(left, right float32) float32 {
+	if left > right {
+		return left
+	}
+	return right
+}
diff --git a/v2/internal/pose/postprocess_test.go b/v2/internal/pose/postprocess_test.go
new file mode 100644
index 0000000..542557f
--- /dev/null
+++ b/v2/internal/pose/postprocess_test.go
@@ -0,0 +1,45 @@
+package pose
+
+import "testing"
+
+func TestParseYOLOv8PoseRestoresCoordinatesAndSuppressesOverlap(t *testing.T) {
+	output := make([]float32, YOLOPoseOutputValues)
+	putDetection(output, 0, 320, 320, 100, 200, 0.90, 330, 340)
+	putDetection(output, 1, 322, 321, 100, 200, 0.80, 332, 341)
+
+	people, err := ParseYOLOv8Pose(output, LetterboxTransform{Scale: 1}, 0.25, 0.70)
+	if err != nil {
+		t.Fatalf("ParseYOLOv8Pose returned an error: %v", err)
+	}
+	if len(people) != 1 {
+		t.Fatalf("people = %d, want one NMS survivor", len(people))
+	}
+	person := people[0]
+	if person.Box != (Box{Left: 270, Top: 220, Right: 370, Bottom: 420}) {
+		t.Fatalf("box = %+v", person.Box)
+	}
+	if point := person.Keypoints[0]; point.X != 330 || point.Y != 340 || point.Confidence != 0.9 {
+		t.Fatalf("first keypoint = %+v", point)
+	}
+}
+
+func TestParseYOLOv8PoseRejectsUnexpectedOutputLength(t *testing.T) {
+	_, err := ParseYOLOv8Pose([]float32{0}, LetterboxTransform{Scale: 1}, 0.25, 0.70)
+	if err == nil {
+		t.Fatal("ParseYOLOv8Pose accepted a malformed output")
+	}
+}
+
+func putDetection(output []float32, candidate int, centerX, centerY, width, height, confidence, keypointX, keypointY float32) {
+	output[0*YOLOPoseCandidateCount+candidate] = centerX
+	output[1*YOLOPoseCandidateCount+candidate] = centerY
+	output[2*YOLOPoseCandidateCount+candidate] = width
+	output[3*YOLOPoseCandidateCount+candidate] = height
+	output[4*YOLOPoseCandidateCount+candidate] = confidence
+	for keypoint := 0; keypoint < YOLOPoseKeypointCount; keypoint++ {
+		base := 5 + keypoint*3
+		output[(base+0)*YOLOPoseCandidateCount+candidate] = keypointX
+		output[(base+1)*YOLOPoseCandidateCount+candidate] = keypointY
+		output[(base+2)*YOLOPoseCandidateCount+candidate] = 0.9
+	}
+}
diff --git a/v2/internal/pose/preprocess.go b/v2/internal/pose/preprocess.go
new file mode 100644
index 0000000..de8ed17
--- /dev/null
+++ b/v2/internal/pose/preprocess.go
@@ -0,0 +1,87 @@
+package pose
+
+import (
+	"fmt"
+	"math"
+)
+
+const letterboxPadding = byte(114)
+
+// PreprocessBGR reproduces the fixed-shape Ultralytics letterbox contract:
+// BGR source pixels are resized with bilinear interpolation, padded in 114
+// gray, converted to RGB/CHW and normalised to [0, 1].
+func PreprocessBGR(frame []byte, width, height, target int) ([]float32, LetterboxTransform, error) {
+	if width <= 0 || height <= 0 || target <= 0 {
+		return nil, LetterboxTransform{}, fmt.Errorf("frame width, height and target must be positive")
+	}
+	if len(frame) != width*height*3 {
+		return nil, LetterboxTransform{}, fmt.Errorf("BGR frame length = %d, want %d", len(frame), width*height*3)
+	}
+
+	scale := math.Min(float64(target)/float64(width), float64(target)/float64(height))
+	resizedWidth := int(math.Round(float64(width) * scale))
+	resizedHeight := int(math.Round(float64(height) * scale))
+	padWidth := target - resizedWidth
+	padHeight := target - resizedHeight
+	padLeft := int(math.Round(float64(padWidth)/2.0 - 0.1))
+	padTop := int(math.Round(float64(padHeight)/2.0 - 0.1))
+	transform := LetterboxTransform{
+		OriginalWidth: width, OriginalHeight: height, InputSize: target,
+		ResizedWidth: resizedWidth, ResizedHeight: resizedHeight,
+		PadLeft: padLeft, PadTop: padTop, Scale: float32(scale),
+	}
+
+	plane := target * target
+	input := make([]float32, 3*plane)
+	padding := float32(letterboxPadding) / 255.0
+	for index := range input {
+		input[index] = padding
+	}
+	for y := 0; y < resizedHeight; y++ {
+		sourceY := clampFloat((float64(y)+0.5)*float64(height)/float64(resizedHeight)-0.5, 0, float64(height-1))
+		y0 := int(math.Floor(sourceY))
+		y1 := minInt(y0+1, height-1)
+		yWeight := float32(sourceY - float64(y0))
+		for x := 0; x < resizedWidth; x++ {
+			sourceX := clampFloat((float64(x)+0.5)*float64(width)/float64(resizedWidth)-0.5, 0, float64(width-1))
+			x0 := int(math.Floor(sourceX))
+			x1 := minInt(x0+1, width-1)
+			xWeight := float32(sourceX - float64(x0))
+			leftTop := (y0*width + x0) * 3
+			rightTop := (y0*width + x1) * 3
+			leftBottom := (y1*width + x0) * 3
+			rightBottom := (y1*width + x1) * 3
+			destination := (padTop+y)*target + padLeft + x
+			for sourceChannel := 0; sourceChannel < 3; sourceChannel++ {
+				value := bilinear(
+					frame[leftTop+sourceChannel], frame[rightTop+sourceChannel],
+					frame[leftBottom+sourceChannel], frame[rightBottom+sourceChannel],
+					xWeight, yWeight,
+				)
+				// BGR source maps to RGB tensor planes.
+				tensorChannel := 2 - sourceChannel
+				// cv2.resize writes uint8 pixels before Ultralytics converts the
+				// image to float; round here to retain that observable contract.
+				input[tensorChannel*plane+destination] = float32(math.Round(float64(value))) / 255.0
+			}
+		}
+	}
+	return input, transform, nil
+}
+
+func bilinear(topLeft, topRight, bottomLeft, bottomRight byte, xWeight, yWeight float32) float32 {
+	top := float32(topLeft)*(1-xWeight) + float32(topRight)*xWeight
+	bottom := float32(bottomLeft)*(1-xWeight) + float32(bottomRight)*xWeight
+	return top*(1-yWeight) + bottom*yWeight
+}
+
+func clampFloat(value, minimum, maximum float64) float64 {
+	return math.Max(minimum, math.Min(maximum, value))
+}
+
+func minInt(left, right int) int {
+	if left < right {
+		return left
+	}
+	return right
+}
diff --git a/v2/internal/pose/preprocess_test.go b/v2/internal/pose/preprocess_test.go
new file mode 100644
index 0000000..0b9d600
--- /dev/null
+++ b/v2/internal/pose/preprocess_test.go
@@ -0,0 +1,39 @@
+package pose
+
+import "testing"
+
+func TestPreprocessBGRUsesUltralyticsPaddingAndRGBCHW(t *testing.T) {
+	// A 2x1 BGR frame letterboxes into a 4x4 tensor with one row of 114-gray
+	// padding above and below. The rightmost source pixel is pure blue in BGR.
+	frame := []byte{0, 0, 0, 255, 0, 0}
+
+	input, transform, err := PreprocessBGR(frame, 2, 1, 4)
+	if err != nil {
+		t.Fatalf("PreprocessBGR returned an error: %v", err)
+	}
+	if transform.ResizedWidth != 4 || transform.ResizedHeight != 2 || transform.PadTop != 1 {
+		t.Fatalf("unexpected transform: %+v", transform)
+	}
+
+	const plane = 16
+	padding := float32(114.0 / 255.0)
+	if got := input[2*plane+0]; got != padding {
+		t.Fatalf("top padding blue = %v, want %v", got, padding)
+	}
+	if got := input[0*plane+1*4+3]; got != 0 {
+		t.Fatalf("red channel = %v, want 0", got)
+	}
+	if got := input[1*plane+1*4+3]; got != 0 {
+		t.Fatalf("green channel = %v, want 0", got)
+	}
+	if got := input[2*plane+1*4+3]; got != 1 {
+		t.Fatalf("blue channel = %v, want 1", got)
+	}
+}
+
+func TestPreprocessBGRRejectsTruncatedFrame(t *testing.T) {
+	_, _, err := PreprocessBGR([]byte{0}, 2, 1, 4)
+	if err == nil {
+		t.Fatal("PreprocessBGR accepted a truncated BGR frame")
+	}
+}
diff --git a/v2/internal/pose/types.go b/v2/internal/pose/types.go
new file mode 100644
index 0000000..54e56d2
--- /dev/null
+++ b/v2/internal/pose/types.go
@@ -0,0 +1,39 @@
+package pose
+
+const (
+	YOLOPoseKeypointCount  = 17
+	YOLOPoseCandidateCount = 8400
+	YOLOPoseChannelCount   = 56
+	YOLOPoseOutputValues   = YOLOPoseChannelCount * YOLOPoseCandidateCount
+)
+
+type Keypoint struct {
+	X          float32
+	Y          float32
+	Confidence float32
+}
+
+type Box struct {
+	Left   float32
+	Top    float32
+	Right  float32
+	Bottom float32
+}
+
+type PersonPose struct {
+	Box        Box
+	Confidence float32
+	Keypoints  [YOLOPoseKeypointCount]Keypoint
+}
+
+// LetterboxTransform maps fixed-square YOLO coordinates back to source pixels.
+type LetterboxTransform struct {
+	OriginalWidth  int
+	OriginalHeight int
+	InputSize      int
+	ResizedWidth   int
+	ResizedHeight  int
+	PadLeft        int
+	PadTop         int
+	Scale          float32
+}
diff --git a/v2/internal/spike/ort.go b/v2/internal/spike/ort.go
index cad8e83..de3d1a5 100644
--- a/v2/internal/spike/ort.go
+++ b/v2/internal/spike/ort.go
@@ -12,6 +12,90 @@ const (
 	poseOutputCount = 1 * 56 * 8400
 )
 
+// Runtime owns one reusable ONNX session.  V2 video replay must keep the
+// model session alive across frames; recreating it for every frame would make
+// event-latency measurements meaningless.
+type Runtime struct {
+	input       *ort.Tensor[float32]
+	output      *ort.Tensor[float32]
+	session     *ort.AdvancedSession
+	initialized bool
+	closed      bool
+}
+
+func OpenRuntime(modelPath, runtimeDLLPath string) (*Runtime, error) {
+	ort.SetSharedLibraryPath(runtimeDLLPath)
+	if err := ort.InitializeEnvironment(); err != nil {
+		return nil, fmt.Errorf("initialize ONNX Runtime: %w", err)
+	}
+	runtime := &Runtime{initialized: true}
+	var err error
+	runtime.input, err = ort.NewEmptyTensor[float32](ort.NewShape(1, 3, poseInputSize, poseInputSize))
+	if err != nil {
+		runtime.Close()
+		return nil, fmt.Errorf("create pose input tensor: %w", err)
+	}
+	runtime.output, err = ort.NewEmptyTensor[float32](ort.NewShape(1, 56, 8400))
+	if err != nil {
+		runtime.Close()
+		return nil, fmt.Errorf("create pose output tensor: %w", err)
+	}
+	runtime.session, err = ort.NewAdvancedSession(
+		modelPath,
+		[]string{"images"},
+		[]string{"output0"},
+		[]ort.Value{runtime.input},
+		[]ort.Value{runtime.output},
+		nil,
+	)
+	if err != nil {
+		runtime.Close()
+		return nil, fmt.Errorf("open pose ONNX session: %w", err)
+	}
+	return runtime, nil
+}
+
+func (runtime *Runtime) Run(input []float32) ([]float32, error) {
+	if runtime == nil || runtime.closed {
+		return nil, fmt.Errorf("ONNX Runtime session is closed")
+	}
+	if len(input) != poseInputCount {
+		return nil, fmt.Errorf("pose input length = %d, want %d", len(input), poseInputCount)
+	}
+	copy(runtime.input.GetData(), input)
+	if err := runtime.session.Run(); err != nil {
+		return nil, fmt.Errorf("run pose ONNX session: %w", err)
+	}
+	output := runtime.output.GetData()
+	if len(output) != poseOutputCount {
+		return nil, fmt.Errorf("pose output length = %d, want %d", len(output), poseOutputCount)
+	}
+	return append([]float32(nil), output...), nil
+}
+
+func (runtime *Runtime) Close() {
+	if runtime == nil || runtime.closed {
+		return
+	}
+	if runtime.session != nil {
+		_ = runtime.session.Destroy()
+		runtime.session = nil
+	}
+	if runtime.output != nil {
+		_ = runtime.output.Destroy()
+		runtime.output = nil
+	}
+	if runtime.input != nil {
+		_ = runtime.input.Destroy()
+		runtime.input = nil
+	}
+	if runtime.initialized {
+		_ = ort.DestroyEnvironment()
+		runtime.initialized = false
+	}
+	runtime.closed = true
+}
+
 // RunPose executes the locked YOLO pose ONNX graph once using the CPU runtime.
 // The caller supplies absolute model and DLL paths so no camera credential or
 // machine-specific path is retained in V2 configuration or source.
@@ -19,45 +103,10 @@ func RunPose(modelPath, runtimeDLLPath string, input []float32) ([]float32, erro
 	if len(input) != poseInputCount {
 		return nil, fmt.Errorf("pose input length = %d, want %d", len(input), poseInputCount)
 	}
-
-	ort.SetSharedLibraryPath(runtimeDLLPath)
-	if err := ort.InitializeEnvironment(); err != nil {
-		return nil, fmt.Errorf("initialize ONNX Runtime: %w", err)
-	}
-	defer func() { _ = ort.DestroyEnvironment() }()
-
-	inputTensor, err := ort.NewTensor(ort.NewShape(1, 3, poseInputSize, poseInputSize), input)
+	runtime, err := OpenRuntime(modelPath, runtimeDLLPath)
 	if err != nil {
-		return nil, fmt.Errorf("create pose input tensor: %w", err)
+		return nil, err
 	}
-	defer func() { _ = inputTensor.Destroy() }()
-
-	outputTensor, err := ort.NewEmptyTensor[float32](ort.NewShape(1, 56, 8400))
-	if err != nil {
-		return nil, fmt.Errorf("create pose output tensor: %w", err)
-	}
-	defer func() { _ = outputTensor.Destroy() }()
-
-	session, err := ort.NewAdvancedSession(
-		modelPath,
-		[]string{"images"},
-		[]string{"output0"},
-		[]ort.Value{inputTensor},
-		[]ort.Value{outputTensor},
-		nil,
-	)
-	if err != nil {
-		return nil, fmt.Errorf("open pose ONNX session: %w", err)
-	}
-	defer func() { _ = session.Destroy() }()
-
-	if err := session.Run(); err != nil {
-		return nil, fmt.Errorf("run pose ONNX session: %w", err)
-	}
-
-	output := outputTensor.GetData()
-	if len(output) != poseOutputCount {
-		return nil, fmt.Errorf("pose output length = %d, want %d", len(output), poseOutputCount)
-	}
-	return append([]float32(nil), output...), nil
+	defer runtime.Close()
+	return runtime.Run(input)
 }
diff --git a/v2/internal/spike/ort_test.go b/v2/internal/spike/ort_test.go
index 1c87741..3af43ba 100644
--- a/v2/internal/spike/ort_test.go
+++ b/v2/internal/spike/ort_test.go
@@ -14,3 +14,13 @@ func TestRunPoseRejectsWrongInputLengthBeforeLoadingRuntime(t *testing.T) {
 		t.Fatalf("RunPose error = %q, want input length error", err)
 	}
 }
+
+func TestOpenRuntimeReportsMissingDLL(t *testing.T) {
+	_, err := OpenRuntime("missing.onnx", "missing.dll")
+	if err == nil {
+		t.Fatal("OpenRuntime accepted a missing ONNX Runtime DLL")
+	}
+	if !strings.Contains(err.Error(), "initialize ONNX Runtime") {
+		t.Fatalf("OpenRuntime error = %q", err)
+	}
+}
diff --git a/v2/internal/spike/preprocess.go b/v2/internal/spike/preprocess.go
index 77431dd..52853da 100644
--- a/v2/internal/spike/preprocess.go
+++ b/v2/internal/spike/preprocess.go
@@ -1,43 +1,14 @@
 package spike
 
-import "fmt"
+import "silverpose/v2/internal/pose"
 
 // LetterboxBGRToNCHW converts one packed BGR frame into the RGB, CHW,
 // float32 tensor expected by the locked 640-pixel YOLO pose ONNX model.
 //
-// It intentionally uses nearest-neighbour scaling for this Spike.  T-303
-// must replace or validate this preprocessing against the V1 implementation
-// before it becomes the V2 production preprocessing path.
+// T-303 aligned the implementation with the fixed-shape Ultralytics
+// letterbox used by the V1/ONNX baseline. New V2 code should import the pose
+// package directly to retain the returned coordinate transform.
 func LetterboxBGRToNCHW(frame []byte, width, height, target int) ([]float32, error) {
-	if width <= 0 || height <= 0 || target <= 0 {
-		return nil, fmt.Errorf("frame width, height and target must be positive")
-	}
-	if len(frame) != width*height*3 {
-		return nil, fmt.Errorf("BGR frame length = %d, want %d", len(frame), width*height*3)
-	}
-
-	scaleWidth := target
-	scaleHeight := height * target / width
-	if scaleHeight > target {
-		scaleHeight = target
-		scaleWidth = width * target / height
-	}
-	padX := (target - scaleWidth) / 2
-	padY := (target - scaleHeight) / 2
-	plane := target * target
-	input := make([]float32, 3*plane)
-
-	for y := 0; y < scaleHeight; y++ {
-		sourceY := y * height / scaleHeight
-		for x := 0; x < scaleWidth; x++ {
-			sourceX := x * width / scaleWidth
-			source := (sourceY*width + sourceX) * 3
-			destination := (padY+y)*target + padX + x
-			input[destination] = float32(frame[source+2]) / 255.0
-			input[plane+destination] = float32(frame[source+1]) / 255.0
-			input[2*plane+destination] = float32(frame[source]) / 255.0
-		}
-	}
-
-	return input, nil
+	input, _, err := pose.PreprocessBGR(frame, width, height, target)
+	return input, err
 }
diff --git a/v2/internal/spike/preprocess_test.go b/v2/internal/spike/preprocess_test.go
index 255fdeb..12f1784 100644
--- a/v2/internal/spike/preprocess_test.go
+++ b/v2/internal/spike/preprocess_test.go
@@ -16,8 +16,9 @@ func TestLetterboxBGRToNCHWPlacesPixelInScaledImage(t *testing.T) {
 	if got := len(input); got != 3*plane {
 		t.Fatalf("input length = %d, want %d", got, 3*plane)
 	}
-	if got := input[2*plane+159*640+320]; got != 0 {
-		t.Fatalf("top padding blue channel = %v, want 0", got)
+	padding := float32(114.0 / 255.0)
+	if got := input[2*plane+159*640+320]; got != padding {
+		t.Fatalf("top padding blue channel = %v, want %v", got, padding)
 	}
 	if got := input[0*plane+320*640+320]; got != 0 {
 		t.Fatalf("red channel = %v, want 0", got)
@@ -25,8 +26,8 @@ func TestLetterboxBGRToNCHWPlacesPixelInScaledImage(t *testing.T) {
 	if got := input[1*plane+320*640+320]; got != 0 {
 		t.Fatalf("green channel = %v, want 0", got)
 	}
-	if got := input[2*plane+320*640+320]; got != 1 {
-		t.Fatalf("blue channel = %v, want 1", got)
+	if got := input[2*plane+320*640+320]; got != float32(128.0/255.0) {
+		t.Fatalf("blue channel = %v, want cv2 INTER_LINEAR value 128/255", got)
 	}
 }