v5.1.0: history tab, portable data folder, optional faststart, new icons & build tools

README.md

@@ -10,10 +10,37 @@ removed, so it needs **no Python and no ML model** — just ffmpeg.
 ## Features
 
 - Drag-and-drop / browse to add videos, reorder, select which to merge.
-- Stream-copy concat with honest real-time progress (and a `+faststart`
-  finalising pass so the output seeks instantly).
+- Stream-copy concat with honest real-time progress. On local NVMe a merge runs
+  at ~95 % of plain file-copy speed — the disk is the limit, not the app.
+- **History** tab: every merge (done, failed, stopped, or interrupted by a
+  crash) with its files, size, time and MB/s. Show the output in its folder, or
+  load the same files again with "Merge again".
 - BiliBili-Live filename helper (`[date][uploader][title]` → readable name).
 - Optionally delete the originals after a successful merge.
+- Optional **Web-optimize MP4 (`+faststart`)**, off by default. It moves the
+  MP4 index to the front so playback can begin mid-download, but ffmpeg has to
+  re-read and re-write the whole file to do it — measured at 17–56 % extra time
+  locally and 60 % over a NAS. Local players don't need it.
+
+## Portable: everything stays in one folder
+
+Nothing is written outside the app folder — not to `%APPDATA%`, not to the
+registry. Copy the folder to another PC and history, theme and options come
+with it:
+
+```
+VideoConcat\
+  Video Concat.exe
+  ffmpeg.exe, ffprobe.exe
+  data\
+    history.jsonl   <- merge history, one JSON line per job
+    running.json    <- only while a merge runs; left behind = "interrupted"
+    webview\        <- WebView2 profile (theme, options)
+```
+
+`data\` is created on first run. If the folder isn't writable (say, under
+Program Files), the app still works but shows a banner and keeps no history.
+It needs the WebView2 runtime, which ships with Windows 10 and 11.
 
 ## Build a standalone (copy-paste) version
 
@@ -28,15 +55,69 @@ dist-portable\VideoConcat\
 ```
 
 Copy that whole `VideoConcat` folder to any Windows PC and run it — nothing else
-to install.
+to install. To **upgrade** an existing copy, replace only `Video Concat.exe`
+and keep its `data\` folder; history carries over.
 
 ### Build requirements (on the build machine only)
 
 - [Node.js](https://nodejs.org/)
 - [Rust](https://rustup.rs/) (`winget install Rustlang.Rustup`)
 - Visual Studio 2022 with the **Desktop development with C++** workload
-- ffmpeg (in `C:\ffmpeg\bin` or on `PATH`)
+- ffmpeg: in `C:\ffmpeg\bin`, on `PATH`, or point `FFMPEG_DIR` at any folder
+  holding `ffmpeg.exe` + `ffprobe.exe` (an existing portable copy works:
+  `set FFMPEG_DIR=%USERPROFILE%\Documents\VideoConcat`)
+
+Building from a network share is slow and fragile (thousands of small files in
+`node_modules` and `target`). Copy the source to a local disk first.
 
 ## Develop
 
 Double-click **`dev.bat`** (hot-reload UI + Rust). Needs ffmpeg on `PATH`.
+In dev mode the `data\` folder sits next to the debug exe in `src-tauri\target\debug\`.
+
+## Test
+
+```
+npm run build            # the Rust tests embed dist/, so build the UI first
+cd src-tauri && cargo test
+```
+
+Covers the BiliBili rename parser, concat-list path escaping (`\\?\` and UNC
+prefixes, quotes), duration reuse, "never delete the output", and history
+crash recovery.
+
+## Benchmark
+
+`tools/bench_concat.py` times each pipeline stage with the exact ffmpeg flags
+the app uses, against the I/O floor of a plain file copy:
+
+```
+python tools/bench_concat.py --ffmpeg-dir <folder with ffmpeg> --make 6 --src D:\bench --dst D:\bench\out
+```
+
+## Icons
+
+The app icon lives as vector art in `src-tauri/icons/icon.svg` — a rounded-square
+gradient tile with the three-filmstrips-into-one-arrow mark. Everything else in
+`src-tauri/icons/` is generated from it:
+
+```
+python tools/make_icons.py
+```
+
+That rewrites the PNGs and `icon.ico` with 8x supersampling and a real alpha
+channel, dropping sub-pixel detail (sprocket holes below 48px, the play-triangle
+knockout below 64px) rather than smearing it. Only the Windows/desktop icons are
+regenerated; the `android/` and `ios/` subfolders are untouched.
+
+To fix the icon on an **already-built** exe without recompiling it:
+
+```
+python tools/patch_exe_icon.py "path\to\Video Concat.exe"
+```
+
+That rewrites only the `RT_ICON` / `RT_GROUP_ICON` resources — `.text`, `.rdata`
+and `.data` come out byte-identical — and keeps a `.bak` alongside. Explorer
+caches icons aggressively, so follow it with `ie4uinit.exe -show`.
+
+Both tools need `pillow` and `numpy`.