Resume interrupted downloads instead of restarting from scratch

MSVC/WinSDK/WDK/DXSDK payloads run into the hundreds of MB to several GB, so a dropped connection or a retry after a transient error used to mean throwing away everything already fetched and starting over from byte 0. Track progress in a dest+".part" file and resume it via an HTTP Range request, falling back to a full restart when the server doesn't honor Range (200 instead of 206) or the local part is stale (416).
Make the wine-not-found error actionable
2026-08-03 15:57:24 +00:00 · 2026-07-25 18:17:59 +10:00 · 2026-07-25 18:17:59 +10:00 · 2026-07-25 18:14:47 +10:00 · 2026-07-25 18:10:56 +10:00 · 2026-07-25 16:23:46 +10:00
50 changed files with 3599 additions and 189 deletions
@@ -43,3 +43,13 @@ jobs:

      - name: go test
        run: go test ./...
+
+      - name: staticcheck
+        uses: dominikh/staticcheck-action@9716614d4101e79b4340dd97b10e54d68234e431 # v1.4.1
+        with:
+          version: latest
+          # Staticcheck itself needs a newer Go than the 1.23 this repo
+          # targets (go.mod's floor) - let the action install its own,
+          # separate from the "Set up Go" step above. min-go-version
+          # defaults to reading go.mod, so diagnostics still target 1.23.
+          install-go: true
@@ -1,37 +1,99 @@
 # vintner

-Cross compile with MSVC on Linux, using Wine — a single-binary Go tool
-inspired by [mstorsjo/msvc-wine](https://github.com/mstorsjo/msvc-wine)'s
-approach (download the real MSVC/WinSDK, wrap the compiler under Wine),
-implemented independently.
+[![CI](https://github.com/Cheviiot/vintner/actions/workflows/ci.yml/badge.svg)](https://github.com/Cheviiot/vintner/actions/workflows/ci.yml)
+[![Release](https://img.shields.io/github/v/release/Cheviiot/vintner)](https://github.com/Cheviiot/vintner/releases/latest)
+[![License: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE.txt)

-Once installed, you invoke the real Microsoft toolchain exactly like on
-Windows: `cl`, `link`, `lib`, `rc`, `midl`, `mc`, `mt`, `dumpbin`, `msbuild`,
-`nmake`, `ml`, `ml64`, `armasm`, `armasm64`, plus trivial `cmd`/`findstr`
-shims, all just work from your `PATH`.
+vintner cross-compiles with the real MSVC toolchain on Linux, using Wine.
+One Go binary drops in as `cl`, `link`, `lib`, `rc`, `midl`, `mc`, `mt`,
+`dumpbin`, `msbuild`, `nmake`, `ml`, `ml64`, `armasm`, `armasm64`, plus
+`cmd`/`findstr` shims, so once installed you invoke the real Microsoft
+tools exactly like on Windows. It handles full MSBuild projects, with
+`--with-wdk` real KMDF/UMDF Windows drivers, and with `--with-dxsdk` the
+real D3DX9 headers/libs.
+
+Inspired by [mstorsjo/msvc-wine](https://github.com/mstorsjo/msvc-wine)'s
+approach: download the real MSVC/WinSDK, wrap the compiler under Wine.
+
+## Contents
+
+- [How it works](#how-it-works)
+- [Installation](#installation)
+- [Quick start](#quick-start)
+- [Commands](#commands)
+- [Invoking tools without PATH](#invoking-tools-without-path)
+- [Diagnosing problems (vintner doctor)](#diagnosing-problems-vintner-doctor)
+- [Building drivers (WDK)](#building-drivers-wdk)
+- [Building against D3DX9 (DirectX SDK)](#building-against-d3dx9-directx-sdk)
+- [Automated/scripted builds](#automatedscripted-builds)
+- [Language](#language)
+- [Shell completion](#shell-completion)
+- [Using clang-cl/lld-link instead of Wine](#using-clang-cllld-link-instead-of-wine)
+- [toolrelay.exe](#toolrelayexe)
+- [Compatibility patches](#compatibility-patches)
+- [Building from source](#building-from-source)
+- [License](#license)

 ## How it works

-`vintner` is one Go binary that behaves differently depending on the name
-it's invoked as (a "multi-call binary", like busybox):
+vintner is a multi-call binary, like busybox: it behaves differently
+depending on the name it's invoked as.

- Invoked as `cl`, `link`, `lib`, ... → it loads a small per-architecture
-  `env.json`, builds the `INCLUDE`/`LIB`/`WINEPATH` environment Wine needs,
-  rewrites absolute unix paths in the arguments into Wine's `z:\...` form
-  (working around [a Wine/cl.exe include-path bug](https://bugs.winehq.org/show_bug.cgi?id=55200)),
-  runs the real `.exe` under `wine`/`wine64`, and rewrites the tool's output
-  back from `z:\...` paths to plain unix paths so your build system's error
+- As `cl`, `link`, `lib`, and the rest: it loads a per-architecture
+  `env.json`, sets `INCLUDE`/`LIB`/`WINEPATH`, and rewrites absolute Unix
+  paths in the arguments to Wine's `z:\...` form (Wine and cl.exe
+  otherwise mishandle relative includes — see
+  [winehq bug 55200](https://bugs.winehq.org/show_bug.cgi?id=55200)). It
+  then runs the real `.exe` under `wine`/`wine64`, and rewrites `z:\...`
+  paths back to Unix paths in the output, so your build system's error
  parsing keeps working.
- Invoked as `vintner` → it exposes the `download`, `install`, `env` and
-  `version` management subcommands described below (each also has a short
-  alias: `dl`, `i`, `e`, `v`; `help`/`h` prints usage).
+- As `vintner`: it exposes the `download`, `install`, `env`, `version`,
+  `doctor` and `completion` subcommands below (short aliases: `dl`, `i`,
+  `e`, `v`; `help`/`h` prints usage).
+
+## Installation
+
+On ALT Linux, via [Nivora](https://github.com/Cheviiot/Nivora):
+
+```bash
+stplr install nivora/vintner
+```
+
+Prebuilt binary, from the [latest release](https://github.com/Cheviiot/vintner/releases/latest):
+
+```bash
+curl -fLo vintner "https://github.com/Cheviiot/vintner/releases/latest/download/vintner-linux-$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/')"
+chmod +x vintner
+sudo install vintner /usr/local/bin/vintner
+```
+
+From source: see [Building from source](#building-from-source).
+
+Either way, `wine`/`wine64`, `msitools` (for `msiextract`) and `git` need
+to be on `PATH` at run time. Nivora installs pull these in automatically
+as package dependencies.
+
+### Prerequisites
+
+- `wine` (or `wine64`) — runs the real `cl.exe`/`link.exe`/etc.
+- `msitools` (`msiextract`) — unpacks the `.msi` payloads MSVC/WinSDK ship as.
+- `git` — applies the compatibility patches bundled with `download` (see
+  [Compatibility patches](#compatibility-patches)).
+- `cabextract` — only needed for `download --with-dxsdk` (see
+  [Building against D3DX9](#building-against-d3dx9-directx-sdk)).
+
+On ALT Linux:
+
+```bash
+pkcon install wine msitools git cabextract
+```

 ## Quick start

 ```bash
-# 1. Download and unpack MSVC + Windows SDK into ~/.vintner (requires
-#    accepting Microsoft's Visual Studio Build Tools license, and msitools
-#    for unpacking .msi payloads). Pass --dest <dir> for a different location.
+# 1. Download and unpack MSVC + Windows SDK into ~/.vintner (accepts
+#    Microsoft's Visual Studio Build Tools license). Pass --dest <dir>
+#    for a different location.
 vintner download --accept-license

 # 2. Wire up the tool wrappers
@@ -42,18 +104,8 @@ export PATH=~/.vintner/bin/x64:$PATH
 cl /nologo /EHsc hello.cpp
 ```

-### Prerequisites
-
- `wine` (or `wine64`) — runs the real `cl.exe`/`link.exe`/etc.
- `msitools` (`msiextract`) — unpacks the `.msi` payloads MSVC/WinSDK ship as.
- `git` — used to apply the small compatibility patches bundled with
-  `download` (see Compatibility patches below).
-
-On ALT Linux:
-
-```bash
-pkcon install wine msitools
-```
+Don't want to touch PATH? Skip step 3 and run tools through vintner
+directly instead - see [Invoking tools without PATH](#invoking-tools-without-path).

 ## Commands

@@ -62,49 +114,143 @@ vintner download (dl) --accept-license [--dest <dir>] [options]   fetch and unpa
 vintner install (i) [dir]                                         wire up wrappers for a downloaded MSVC
 vintner env (e) --bin <dir>/bin/<arch>                            print INCLUDE/LIB for native clang-cl/lld-link use
 vintner version (v)                                               print the version
+vintner doctor                                                    check wine/toolchain setup
 vintner help (h)                                                  print usage
+vintner completion bash|zsh                                       print a shell completion script
 ```

 `--dest`/`[dir]` both default to `~/.vintner` when omitted.

 `download`'s main options: `--msvc-version`, `--sdk-version`,
-`--architecture`, `--host-arch`, `--only-host`, `--with-wdk` (also fetch the
-Windows Driver Kit, for building KMDF/UMDF drivers), `--ignore`,
-`--only-download`, `--only-unpack`, `--keep-unpack`, `--skip-patch`,
-`--cache`, `--language`, `--include-optional`, `--skip-recommended`,
-`--major`, `--preview`, `--manifest`, `--list-workloads`,
-`--list-components`, `--print-deps-tree`. Run `vintner download -h` for the
-full list with descriptions.
+`--architecture` (repeatable: `x86`/`x64`/`arm`/`arm64`/`host`),
+`--host-arch`, `--only-host`, `--with-wdk` (see below), `--with-dxsdk`
+(see below), `--ignore` (repeatable), `--only-download`, `--only-unpack`,
+`--keep-unpack`, `--skip-patch`, `--cache`, `--language`,
+`--include-optional`, `--skip-recommended`, `--major`, `--preview`,
+`--manifest`, `--list-workloads`, `--list-components`,
+`--print-deps-tree`. Run `vintner download -h` for the full list with
+descriptions.

 `--list-workloads`/`--list-components` print every workload/component id
-(with its human-readable title) available in the fetched manifest and exit
-without downloading anything - useful for discovering what to pass as a bare
-package id or via `--with-*`. `--print-deps-tree` prints the dependency tree
-of whatever would actually be selected (honoring every other flag), also
-without downloading.
+and its human-readable title from the fetched manifest, then exit
+without downloading anything. Useful for finding what to pass as a bare
+package id or through `--with-*`. `--print-deps-tree` prints the
+dependency tree of whatever would actually be selected — honoring every
+other flag — without downloading anything.

-### Building drivers (WDK)
+## Invoking tools without PATH

-`vintner download --with-wdk` additionally fetches the Windows Driver Kit
-(headers, import libs, and the MSBuild `WindowsKernelModeDriver10.0`/
-`WindowsUserModeDriver10.0` PlatformToolsets) so `msbuild` can build real
-KMDF/UMDF drivers - compiling, linking, INF stamping and the `Inf2Cat`
-signability check (with `SignMode=off`) all work under Wine. Verified
-end-to-end against a real sample driver from
+`cl`, `link`, `msbuild`, and the rest also work as `vintner <tool>
+[args...]`, with no need to add `<dest>/bin/<arch>` to `PATH` or rely on
+the symlinks `install` sets up there:
+
+```bash
+vintner cl /nologo /EHsc hello.cpp
+vintner msbuild MyProject.sln
+```
+
+Resolves the toolchain to use from `VINTNER_BIN` if set (same meaning as
+`env --bin`: point it at a `<dest>/bin/<arch>` directory directly — useful
+for a non-default `--dest`, or to pick a specific architecture when more
+than one is installed), otherwise defaults to
+`~/.vintner/bin/<host-arch>`, the layout a plain `vintner download &&
+vintner install` with no `--dest` override produces.
+
+## Diagnosing problems (vintner doctor)
+
+```bash
+vintner doctor
+```
+
+Checks the things vintner actually needs at runtime — that `wine`/`wine64`
+is on `PATH` and actually runs, that `msitools`/`cabextract` are present,
+and that every installed `<dest>/bin/<arch>` toolchain (or the one
+`VINTNER_BIN` points at) has its MSVC/SDK/MSBuild directories in place —
+and prints a pass/fail checklist. Exits non-zero if anything failed.
+Useful before filing a bug, or after a `download`/`install` that seemed to
+finish but left tools failing in confusing ways.
+
+## Building drivers (WDK)
+
+`--with-wdk` also fetches the Windows Driver Kit: headers, import libs,
+and the MSBuild `WindowsKernelModeDriver10.0`/`WindowsUserModeDriver10.0`
+PlatformToolsets.
+
+```bash
+vintner download --accept-license --with-wdk
+```
+
+With it, `msbuild` builds real KMDF/UMDF drivers — compiling, linking,
+INF stamping, and the `Inf2Cat` signability check (`SignMode=off`) all
+work under Wine. Tested against a real sample driver from
 [microsoft/Windows-driver-samples](https://github.com/microsoft/Windows-driver-samples).
-Only x64 and arm64 targets have a WDK package upstream (no x86/arm).
+Only x64 and arm64 targets have a WDK package upstream; there's no x86 or
+arm one.

-### Language
+## Building against D3DX9 (DirectX SDK)

-CLI messages (usage text, progress lines, prompts) are in English by
-default. Set `VINTNER_LANG=ru` (or have a `ru`-prefixed `LC_ALL`/
-`LC_MESSAGES`/`LANG`, e.g. `ru_RU.UTF-8`) for Russian. Deeper error text
-bubbled up from internal packages stays in English.
+`--with-dxsdk` fetches the DirectX SDK (June 2010) — the last standalone
+release of D3DX9/10/11, XInput and XAudio2, dropped from the Windows SDK
+entirely once D3DX was deprecated. It unpacks the real headers and x86/x64
+import libs (`d3dx9.h`/`d3dx9.lib` included) to `<dest>/DXSDK`.

-### Using clang-cl/lld-link instead of Wine
+```bash
+vintner download --accept-license --with-dxsdk
+```

-You don't need Wine at all if you drive the (nonredistributable) MSVC/WinSDK
-headers and libraries with Clang/LLD in MSVC-compatible mode:
+Point your project's `IncludePath`/`LibraryPath` at
+`<dest>/DXSDK/Include` and `<dest>/DXSDK/Lib/x86` or `<dest>/DXSDK/Lib/x64`.
+Requires `cabextract` on `PATH` (the installer is a self-extracting CAB
+archive).
+
+## Automated/scripted builds
+
+Every tool invocation runs unbounded by default, same as the real thing on
+Windows. Set `VINTNER_TIMEOUT` (a `time.ParseDuration` string, e.g. `30m`,
+`2h`) to have vintner kill and fail a build that runs longer than that
+instead of hanging forever - meant for CI and other unattended callers, not
+interactive use. This guards against one confirmed failure mode: an
+MSBuild node-reuse worker (`/nodeReuse:true` is MSBuild's own default) can
+survive its parent process under Wine and, if a prior build was
+interrupted mid-compile, come back wedged - reused by the next `msbuild`
+call and failing every subsequent build with a confusing, unrelated-looking
+error, indefinitely, until it's killed by hand. vintner already forces
+`/nodeReuse:false` on every `msbuild` invocation to prevent this in the
+first place; `VINTNER_TIMEOUT` is the backstop for whatever else might
+wedge under Wine that isn't MSBuild-specific.
+
+```bash
+VINTNER_TIMEOUT=30m msbuild MyProject.sln
+```
+
+## Language
+
+CLI text (usage, progress lines, prompts) defaults to English. Set
+`VINTNER_LANG=ru` (or a `ru`-prefixed `LC_ALL`/`LC_MESSAGES`/`LANG`, e.g.
+`ru_RU.UTF-8`) for Russian:
+
+```bash
+VINTNER_LANG=ru vintner help
+```
+
+Error text from internal packages stays in English regardless.
+
+## Shell completion
+
+Already set up if you installed via Nivora. Otherwise:
+
+```bash
+source <(vintner completion bash)   # or add to ~/.bashrc
+source <(vintner completion zsh)    # or add to ~/.zshrc
+```
+
+Completes subcommands, including the short aliases, `download`'s flags,
+and directory arguments for `install`/`env --bin`.
+
+## Using clang-cl/lld-link instead of Wine
+
+The MSVC/WinSDK headers and libraries work directly with Clang/LLD in
+MSVC-compatible mode. No Wine needed:

 ```bash
 eval "$(vintner env --bin ~/.vintner/bin/x64)"
@@ -112,49 +258,44 @@ clang-cl -c hello.c
 lld-link hello.obj -out:hello.exe
 ```

+## toolrelay.exe
+
+`install` compiles `assets/vendor/toolrelay.cpp`, a small native Windows
+launcher, with the freshly-installed host-arch `cl.exe`. This is
+best-effort: if `wine` isn't available yet, or the compile fails, install
+still succeeds, and tool invocations just skip it. When present, every
+non-MSBuild tool call is routed through it via two named FIFOs.
+
+That's what lets `mt.exe`'s CMake-compatibility exit code
+(`0x41020001` → `0xbb`) survive Wine's own exit-code truncation: a native
+Windows process can read the real 32-bit exit code via
+`GetExitCodeProcess()` before Wine collapses it to a single byte on the
+way back to Unix.
+
+## Compatibility patches
+
+`download` applies a few small patches (`assets/patches`) to the
+downloaded MSVC/WinSDK tree, so `VsDevCmd.bat` and MSBuild's
+SDK-detection props work without a Windows Registry, which doesn't exist
+under Wine. They look up the SDK directly under the VS install root
+instead of querying the registry, skip telemetry, and don't fail devcmd
+setup when an optional component (ConnectionManagerExe, bundled
+CMake/Ninja) is missing.
+
 ## Building from source

 ```bash
 go build -o vintner ./cmd/vintner
+go vet ./...
+go test ./...
 ```

-Go 1.23+ is all you need to build it; `wine`/`msitools` are only needed at
-run time (`install`/tool invocation and `download` respectively).
-
-## toolrelay.exe
-
-`install` compiles `assets/vendor/toolrelay.cpp` (a small native Windows
-launcher, original to this project) with the freshly-installed host-arch
-`cl.exe` (best-effort: if `wine` isn't present yet, or the compile fails,
-install still succeeds and the wrapper runtime just falls back to invoking
-tools directly through wine). When present, every non-MSBuild tool
-invocation is routed through it via two named FIFOs. This is what lets
-`mt.exe`'s CMake-compatibility exit-code translation (`0x41020001` → `0xbb`)
-survive Wine's own exit-code truncation: only a native Windows process
-observing the untranslated code via `GetExitCodeProcess()` can catch it
-before Wine marshals the process exit back to Unix and drops everything but
-the low byte.
-
-## Compatibility patches
-
-`download` applies a handful of small patches (`assets/patches`) to the
-downloaded MSVC/WinSDK tree - independently written for this project - that
-make `VsDevCmd.bat` and MSBuild's SDK-detection props work without a
-Windows Registry (which doesn't exist under Wine): they check the SDK
-directly under the VS install root instead of querying the registry, skip
-telemetry, and don't hard-fail devcmd setup when an optional component
-(ConnectionManagerExe, bundled CMake/Ninja) wasn't downloaded.
-
-## Known gaps
-
-None currently tracked. Download/select/unpack/install, general MSBuild
-projects, WDK driver builds, dependency-tree printing, and
-workload/component listing are all implemented and verified against real
-projects.
+Go 1.23+ builds it. `wine`/`msitools` are only needed at run time, for
+`install`/tool invocation and `download` respectively.

 ## License

-MIT, see [LICENSE.txt](LICENSE.txt) - covers vintner's own source only. The
-MSVC Build Tools / Windows SDK / WDK that `download` fetches remain governed
-by Microsoft's own license (accepted via `--accept-license`), same as with
+MIT (see [LICENSE.txt](LICENSE.txt)) for vintner's own source. The MSVC
+Build Tools, Windows SDK, and WDK that `download` fetches stay under
+Microsoft's own license (accepted via `--accept-license`), same as with
 any other way of obtaining them.
@@ -79,8 +79,16 @@ HANDLE MakeKillOnCloseJob() {
 }

 bool IsMtExe(const wchar_t *path) {
-  const wchar_t *name = wcsrchr(path, L'\\');
-  name = name ? name + 1 : path;
+  // vintner passes toolExePath straight through from Go's filepath.Join,
+  // which uses forward slashes even for a path that's about to be handed
+  // to a native Windows process - so the separator here isn't reliably
+  // '\\'. Check both; using whichever comes later in the string covers a
+  // mixed-separator path too.
+  const wchar_t *back = wcsrchr(path, L'\\');
+  const wchar_t *fwd = wcsrchr(path, L'/');
+  const wchar_t *sep = back;
+  if (fwd && (!sep || fwd > sep)) sep = fwd;
+  const wchar_t *name = sep ? sep + 1 : path;
  return _wcsicmp(name, L"mt.exe") == 0;
 }

@@ -0,0 +1,167 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/Cheviiot/vintner/internal/wrapper"
+)
+
+// runCompletion prints a shell completion script for shell ("bash" or
+// "zsh") to stdout, meant to be sourced directly:
+//
+//	source <(vintner completion bash)   # or add to ~/.bashrc
+//	source <(vintner completion zsh)    # or add to ~/.zshrc
+//
+// The flag lists below are hand-maintained alongside download.go/env.go's
+// flag.FlagSet definitions rather than generated from them - there's no
+// reflection-friendly registry to walk, and the flag set rarely changes.
+// The tool name list isn't hand-maintained, though (see wrapper.ToolNames):
+// a hand-copied one already went stale once already for a flag
+// (--with-dxsdk missing from here after being added to download.go), and a
+// list of every wrapped tool has more entries and changes for the same
+// reasons the flag lists do, so it's worth generating for real.
+func runCompletion(args []string) int {
+	if len(args) != 1 {
+		fmt.Println("usage: vintner completion bash|zsh")
+		return 1
+	}
+	switch args[0] {
+	case "bash":
+		fmt.Print(bashCompletionScript())
+		return 0
+	case "zsh":
+		fmt.Print(zshCompletionScript())
+		return 0
+	default:
+		fmt.Printf("vintner completion: unsupported shell %q (want bash or zsh)\n", args[0])
+		return 1
+	}
+}
+
+const downloadFlags = "--dest --cache --major --preview --manifest --accept-license " +
+	"--msvc-version --sdk-version --host-arch --only-host --language " +
+	"--include-optional --skip-recommended --only-download --only-unpack " +
+	"--keep-unpack --skip-patch --list-workloads --list-components " +
+	"--print-deps-tree --with-wdk --with-dxsdk --architecture --ignore -h --help"
+
+// subcommandNames lists vintner's own management subcommands (long form
+// plus every short alias) - unlike the wrapped-tool names, these really are
+// fixed enough to hand-maintain: adding one is rare and always touches
+// main.go's dispatch switch right next to this file anyway.
+const subcommandNames = "download dl install i env e version v doctor help h completion"
+
+func bashCompletionScript() string {
+	return `# vintner bash completion - eval "$(vintner completion bash)"
+_vintner_complete() {
+    local cur cmd
+    COMPREPLY=()
+    cur="${COMP_WORDS[COMP_CWORD]}"
+    cmd="${COMP_WORDS[1]}"
+
+    if [ "$COMP_CWORD" -eq 1 ]; then
+        COMPREPLY=($(compgen -W "` + subcommandNames + ` ` + strings.Join(wrapper.ToolNames(), " ") + `" -- "$cur"))
+        return 0
+    fi
+
+    case "$cmd" in
+        download|dl)
+            COMPREPLY=($(compgen -W "` + downloadFlags + `" -- "$cur"))
+            ;;
+        install|i)
+            COMPREPLY=($(compgen -d -- "$cur"))
+            ;;
+        env|e)
+            COMPREPLY=($(compgen -W "--bin -h --help" -- "$cur"))
+            ;;
+        completion)
+            COMPREPLY=($(compgen -W "bash zsh" -- "$cur"))
+            ;;
+    esac
+    return 0
+}
+complete -F _vintner_complete vintner
+`
+}
+
+func zshCompletionScript() string {
+	var toolEntries strings.Builder
+	for _, name := range wrapper.ToolNames() {
+		fmt.Fprintf(&toolEntries, "        %q\n", name+":run this tool directly, e.g. \"vintner "+name+" ...\"")
+	}
+
+	return `#compdef vintner
+# vintner zsh completion - source <(vintner completion zsh)
+
+_vintner() {
+    local -a subcommands
+    subcommands=(
+        'download:fetch and unpack MSVC/WinSDK/WDK'
+        'dl:alias for download'
+        'install:wire up wrappers for a downloaded MSVC'
+        'i:alias for install'
+        'env:print INCLUDE/LIB for native clang-cl/lld-link use'
+        'e:alias for env'
+        'version:print the version'
+        'v:alias for version'
+        'doctor:check wine/toolchain setup'
+        'help:print usage'
+        'h:alias for help'
+        'completion:print a shell completion script'
+` + toolEntries.String() + `    )
+
+    if (( CURRENT == 2 )); then
+        _describe 'command' subcommands
+        return
+    fi
+
+    case "${words[2]}" in
+        download|dl)
+            local -a flags
+            flags=(
+                '--dest[directory to install into]:directory:_files -/'
+                '--cache[persistent download cache directory]:directory:_files -/'
+                '--major[major VS version]:version:'
+                '--preview[use the preview/insiders channel]'
+                '--manifest[use a predownloaded installer manifest file]:file:_files'
+                '--accept-license[do not prompt for accepting the license]'
+                '--msvc-version[install a specific MSVC toolchain version]:version:'
+                '--sdk-version[install a specific Windows SDK version]:version:'
+                '--host-arch[host architecture]:arch:(x86 x64 arm64)'
+                '--only-host[only download packages matching the host architecture]'
+                '--language[preferred package language]:language:'
+                '--include-optional[include all optional dependencies]'
+                '--skip-recommended[skip recommended dependencies]'
+                '--only-download[stop after downloading package files]'
+                '--only-unpack[unpack without pruning to just the CLI tools]'
+                '--keep-unpack[keep the scratch unpack dir]'
+                '--skip-patch[do not apply the Wine compatibility patches]'
+                '--list-workloads[list available workloads and exit]'
+                '--list-components[list available components and exit]'
+                '--print-deps-tree[print the dependency tree and exit]'
+                '--with-wdk[also fetch the Windows Driver Kit]'
+                '--with-dxsdk[also fetch the DirectX SDK]'
+                '--architecture[target architecture]:arch:(x86 x64 arm arm64 host)'
+                '--ignore[package id to skip]:package id:'
+                '-h[show help]'
+                '--help[show help]'
+            )
+            _arguments $flags
+            ;;
+        install|i)
+            _files -/
+            ;;
+        env|e)
+            _arguments \
+                '--bin[bin/<arch> directory produced by install]:directory:_files -/' \
+                '-h[show help]' '--help[show help]'
+            ;;
+        completion)
+            _values 'shell' bash zsh
+            ;;
+    esac
+}
+
+_vintner "$@"
+`
+}
@@ -0,0 +1,64 @@
+package main
+
+import (
+	"os/exec"
+	"strings"
+	"testing"
+
+	"github.com/Cheviiot/vintner/internal/wrapper"
+)
+
+// TestCompletionScriptsAreSyntacticallyValid catches the easy way to break
+// these: a typo in the hand-maintained flag lists that produces invalid
+// shell syntax. It shells out to bash/zsh -n rather than parsing the script
+// itself, so it's testing exactly what a user's shell would see.
+func TestCompletionScriptsAreSyntacticallyValid(t *testing.T) {
+	for _, tc := range []struct {
+		shell  string
+		script string
+	}{
+		{"bash", bashCompletionScript()},
+		{"zsh", zshCompletionScript()},
+	} {
+		t.Run(tc.shell, func(t *testing.T) {
+			if _, err := exec.LookPath(tc.shell); err != nil {
+				t.Skipf("%s not installed", tc.shell)
+			}
+			cmd := exec.Command(tc.shell, "-n", "/dev/stdin")
+			cmd.Stdin = strings.NewReader(tc.script)
+			if out, err := cmd.CombinedOutput(); err != nil {
+				t.Fatalf("%s -n rejected the completion script: %v\n%s", tc.shell, err, out)
+			}
+		})
+	}
+}
+
+// TestCompletionScriptsListEveryTool guards against the exact staleness bug
+// found and fixed alongside this test: a hand-copied tool/flag list here
+// drifting from the real set in internal/wrapper (or download.go's flags)
+// as tools/flags get added. Every current tool name must appear in both
+// generated scripts.
+func TestCompletionScriptsListEveryTool(t *testing.T) {
+	bash := bashCompletionScript()
+	zsh := zshCompletionScript()
+	for _, name := range wrapper.ToolNames() {
+		if !strings.Contains(bash, name) {
+			t.Errorf("bash completion script doesn't mention tool %q", name)
+		}
+		if !strings.Contains(zsh, name+":") {
+			t.Errorf("zsh completion script doesn't mention tool %q", name)
+		}
+	}
+}
+
+func TestRunCompletionUnknownShell(t *testing.T) {
+	if code := runCompletion([]string{"fish"}); code != 1 {
+		t.Errorf("runCompletion([\"fish\"]) = %d, want 1", code)
+	}
+	if code := runCompletion(nil); code != 1 {
+		t.Errorf("runCompletion(nil) = %d, want 1", code)
+	}
+	if code := runCompletion([]string{"bash", "extra"}); code != 1 {
+		t.Errorf("runCompletion with extra arg = %d, want 1", code)
+	}
+}
@@ -0,0 +1,176 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"time"
+
+	"github.com/Cheviiot/vintner/internal/i18n"
+	"github.com/Cheviiot/vintner/internal/wineenv"
+)
+
+// runDoctor checks the pieces vintner actually needs at runtime - wine
+// itself, the optional extraction tools download needs, and every
+// installed <dest>/bin/<arch> toolchain's on-disk layout - and prints a
+// pass/fail checklist. The point is surfacing a broken setup as a short,
+// readable report instead of a wine-specific error buried deep inside a
+// build (see internal/wineenv.FindWine's own error, which this reuses).
+func runDoctor(args []string) int {
+	if len(args) > 0 && (args[0] == "-h" || args[0] == "--help") {
+		fmt.Fprintln(os.Stderr, i18n.T("doctor.usage"))
+		return 1
+	}
+
+	d := &doctorReport{}
+	d.checkWine()
+	d.checkExtractionTools()
+	d.checkToolchains()
+
+	if d.failed {
+		fmt.Println(i18n.T("doctor.summary_fail"))
+		return 1
+	}
+	fmt.Println(i18n.T("doctor.summary_ok"))
+	return 0
+}
+
+type doctorReport struct {
+	failed bool
+}
+
+func (d *doctorReport) ok(format string, args ...any) {
+	fmt.Printf("  [ok]   "+format+"\n", args...)
+}
+
+func (d *doctorReport) warn(format string, args ...any) {
+	fmt.Printf("  [warn] "+format+"\n", args...)
+}
+
+func (d *doctorReport) fail(format string, args ...any) {
+	fmt.Printf("  [FAIL] "+format+"\n", args...)
+	d.failed = true
+}
+
+func (d *doctorReport) checkWine() {
+	fmt.Println(i18n.T("doctor.section_wine"))
+
+	wineBin, err := wineenv.FindWine()
+	if err != nil {
+		d.fail("%s", err)
+		return
+	}
+	d.ok("found: %s", wineBin)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	out, err := exec.CommandContext(ctx, wineBin, "--version").Output()
+	if err != nil {
+		d.fail("%s --version failed: %v", wineBin, err)
+		return
+	}
+	d.ok("runs: %s", trimNewline(string(out)))
+}
+
+func (d *doctorReport) checkExtractionTools() {
+	fmt.Println(i18n.T("doctor.section_extract"))
+
+	if _, err := exec.LookPath("msiextract"); err != nil {
+		d.warn(i18n.T("doctor.msitools_missing"))
+	} else {
+		d.ok("msitools: found (needed by `vintner download`)")
+	}
+
+	if _, err := exec.LookPath("cabextract"); err != nil {
+		d.warn(i18n.T("doctor.cabextract_missing"))
+	} else {
+		d.ok("cabextract: found (needed by --with-wdk/--with-dxsdk)")
+	}
+}
+
+func (d *doctorReport) checkToolchains() {
+	fmt.Println(i18n.T("doctor.section_toolchain"))
+
+	if binDir := os.Getenv("VINTNER_BIN"); binDir != "" {
+		d.checkToolchainAt(binDir, "VINTNER_BIN="+binDir)
+		return
+	}
+
+	def, err := defaultToolchainDir()
+	if err != nil {
+		d.fail("%s", err)
+		return
+	}
+	destBin := filepath.Join(def, "bin")
+	archDirs := installedArchDirs(destBin)
+	if len(archDirs) == 0 {
+		d.fail(i18n.T("doctor.no_toolchain", destBin))
+		return
+	}
+	for _, arch := range archDirs {
+		d.checkToolchainAt(filepath.Join(destBin, arch), arch)
+	}
+}
+
+// installedArchDirs returns the subdirectories of destBin that carry their
+// own env.json, i.e. every architecture `vintner install` actually set up
+// (there can be more than one - e.g. x86 and x64 side by side).
+func installedArchDirs(destBin string) []string {
+	entries, err := os.ReadDir(destBin)
+	if err != nil {
+		return nil
+	}
+	var dirs []string
+	for _, e := range entries {
+		if !e.IsDir() {
+			continue
+		}
+		if _, err := os.Stat(filepath.Join(destBin, e.Name(), wineenv.ConfigFileName)); err == nil {
+			dirs = append(dirs, e.Name())
+		}
+	}
+	return dirs
+}
+
+func (d *doctorReport) checkToolchainAt(binDir, label string) {
+	cfg, err := wineenv.Load(binDir)
+	if err != nil {
+		d.fail("%s: %s", label, err)
+		return
+	}
+	baseUnix, err := wineenv.FindBaseUnix(binDir)
+	if err != nil {
+		d.fail("%s: %s", label, err)
+		return
+	}
+	d.ok("%s: MSVC %s, SDK %s, root %s", label, cfg.MSVCVer, cfg.SDKVer, baseUnix)
+
+	paths := wineenv.NewPaths(cfg, baseUnix)
+	for _, dir := range []struct{ name, path string }{
+		{"MSVC bin", paths.BinDir},
+		{"SDK bin", paths.SDKBinDir},
+		{"MSBuild bin", paths.MSBuildBinDir},
+	} {
+		if fi, err := os.Stat(dir.path); err != nil || !fi.IsDir() {
+			d.fail("%s: %s missing: %s", label, dir.name, dir.path)
+		} else {
+			d.ok("%s: %s: %s", label, dir.name, dir.path)
+		}
+	}
+
+	relay := filepath.Join(baseUnix, "bin", "toolrelay.exe")
+	if fi, err := os.Stat(relay); err != nil || fi.IsDir() {
+		d.warn("%s: toolrelay.exe not built (mt.exe's CMake exit-code translation won't apply; re-run `vintner install` to retry)", label)
+	} else {
+		d.ok("%s: toolrelay.exe: %s", label, relay)
+	}
+}
+
+func trimNewline(s string) string {
+	for len(s) > 0 && (s[len(s)-1] == '\n' || s[len(s)-1] == '\r') {
+		s = s[:len(s)-1]
+	}
+	return s
+}
@@ -0,0 +1,83 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/Cheviiot/vintner/internal/wineenv"
+)
+
+func TestRunDoctorUsage(t *testing.T) {
+	for _, flag := range []string{"-h", "--help"} {
+		if code := runDoctor([]string{flag}); code != 1 {
+			t.Errorf("runDoctor([%q]) = %d, want 1", flag, code)
+		}
+	}
+}
+
+func TestDoctorReportOkWarnFail(t *testing.T) {
+	d := &doctorReport{}
+	d.ok("fine")
+	d.warn("meh")
+	if d.failed {
+		t.Fatal("ok/warn must not mark the report as failed")
+	}
+	d.fail("broken")
+	if !d.failed {
+		t.Fatal("fail must mark the report as failed")
+	}
+}
+
+func TestInstalledArchDirsFindsOnlyDirsWithEnvJSON(t *testing.T) {
+	destBin := t.TempDir()
+	for _, dir := range []string{"x64", "x86", "not-a-toolchain"} {
+		if err := os.MkdirAll(filepath.Join(destBin, dir), 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, dir := range []string{"x64", "x86"} {
+		if err := os.WriteFile(filepath.Join(destBin, dir, wineenv.ConfigFileName), []byte("{}"), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	got := installedArchDirs(destBin)
+	want := map[string]bool{"x64": true, "x86": true}
+	if len(got) != len(want) {
+		t.Fatalf("installedArchDirs = %v, want exactly %v", got, want)
+	}
+	for _, arch := range got {
+		if !want[arch] {
+			t.Errorf("installedArchDirs returned unexpected entry %q", arch)
+		}
+	}
+}
+
+func TestInstalledArchDirsMissingDir(t *testing.T) {
+	if got := installedArchDirs(filepath.Join(t.TempDir(), "does-not-exist")); got != nil {
+		t.Errorf("installedArchDirs on a missing dir = %v, want nil", got)
+	}
+}
+
+func TestCheckToolchainAtMissingEnvJSON(t *testing.T) {
+	d := &doctorReport{}
+	d.checkToolchainAt(t.TempDir(), "test")
+	if !d.failed {
+		t.Error("checkToolchainAt against a dir with no env.json should fail the report")
+	}
+}
+
+func TestTrimNewline(t *testing.T) {
+	cases := map[string]string{
+		"wine-9.0\n":   "wine-9.0",
+		"wine-9.0\r\n": "wine-9.0",
+		"wine-9.0":     "wine-9.0",
+		"":             "",
+	}
+	for in, want := range cases {
+		if got := trimNewline(in); got != want {
+			t.Errorf("trimNewline(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
@@ -10,6 +10,7 @@ import (

 	"github.com/Cheviiot/vintner/internal/download"
 	"github.com/Cheviiot/vintner/internal/i18n"
+	"github.com/Cheviiot/vintner/internal/lock"
 )

 func runDownload(args []string) int {
@@ -35,6 +36,7 @@ func runDownload(args []string) int {
 	listComponents := fs.Bool("list-components", false, "list available components from the manifest and exit, without downloading anything")
 	printDepsTree := fs.Bool("print-deps-tree", false, "print the dependency tree of the selected packages and exit, without downloading anything")
 	withWDK := fs.Bool("with-wdk", false, "also fetch and install the Windows Driver Kit (headers, libs and MSBuild driver PlatformToolsets, for building KMDF/UMDF drivers)")
+	withDXSDK := fs.Bool("with-dxsdk", false, "also fetch and install the DirectX SDK (June 2010): real D3DX9/10/11, XInput and XAudio2 headers and import libs, dropped from the modern Windows SDK")
 	var archsFlag stringList
 	fs.Var(&archsFlag, "architecture", "target architecture to include (x86, x64, arm, arm64, host); repeatable")
 	var ignoreFlag stringList
@@ -45,6 +47,17 @@ func runDownload(args []string) int {
 	}
 	packages := fs.Args()

+	for _, a := range archsFlag {
+		if !validArchitectures[a] {
+			fmt.Fprintf(os.Stderr, "vintner download: invalid --architecture %q (expected one of x86, x64, arm, arm64, host)\n", a)
+			return 2
+		}
+	}
+	if *hostArch != "" && !validHostArchs[*hostArch] {
+		fmt.Fprintf(os.Stderr, "vintner download: invalid --host-arch %q (expected one of x86, x64, arm64)\n", *hostArch)
+		return 2
+	}
+
 	opts := &download.Options{
 		Package:         packages,
 		Ignore:          []string(ignoreFlag),
@@ -165,6 +178,12 @@ func runDownload(args []string) int {
 		fmt.Fprintln(os.Stderr, "vintner download:", err)
 		return 1
 	}
+	unlock, err := lock.Acquire(destAbs)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "vintner download:", err)
+		return 1
+	}
+	defer unlock()

 	unpack := destAbs
 	if !*onlyUnpack {
@@ -208,6 +227,13 @@ func runDownload(args []string) int {
 		}
 	}

+	if *withDXSDK && !*onlyUnpack {
+		if err := downloadDXSDK(cache, destAbs); err != nil {
+			fmt.Fprintln(os.Stderr, "vintner download:", err)
+			return 1
+		}
+	}
+
 	fmt.Println(i18n.T("download.done", destAbs))
 	return 0
 }
@@ -244,6 +270,18 @@ func downloadWDK(opts *download.Options, selected []*download.Package, cache, de
 	return nil
 }

+// downloadDXSDK fetches and unpacks the DirectX SDK (June 2010) into
+// destAbs/DXSDK. See internal/download/dxsdk.go for why this is a separate
+// download path from the rest of ExpandSelection/FetchPayloads/Unpack.
+func downloadDXSDK(cache, destAbs string) error {
+	dxsdkDir, err := download.DownloadDXSDK(cache, destAbs)
+	if err != nil {
+		return err
+	}
+	fmt.Print(i18n.T("download.dxsdk_installed", dxsdkDir))
+	return nil
+}
+
 func contains(list []string, v string) bool {
 	for _, s := range list {
 		if s == v {
@@ -267,6 +305,9 @@ func printPackageList(headerKey string, pkgs []*download.Package, language strin
 	}
 }

+var validArchitectures = map[string]bool{"x86": true, "x64": true, "arm": true, "arm64": true, "host": true}
+var validHostArchs = map[string]bool{"x86": true, "x64": true, "arm64": true}
+
 func detectHostArch() string {
 	if runtime.GOARCH == "arm64" {
 		return "arm64"
@@ -0,0 +1,40 @@
+package main
+
+import "testing"
+
+// TestRunDownloadRejectsInvalidArchFlags exercises the validation added
+// after the flags are parsed, which must reject typos before runDownload
+// gets anywhere near the network (FetchChannelManifest) - these tests would
+// hang/fail on network access if that ordering ever regressed.
+func TestRunDownloadRejectsInvalidArchFlags(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		args []string
+	}{
+		{"bad architecture", []string{"--architecture", "x866"}},
+		{"bad architecture, valid mixed with invalid", []string{"--architecture", "x64", "--architecture", "sparc"}},
+		{"bad host-arch", []string{"--host-arch", "sparc"}},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if code := runDownload(tc.args); code != 2 {
+				t.Errorf("runDownload(%v) = %d, want 2", tc.args, code)
+			}
+		})
+	}
+}
+
+func TestValidArchitectureSets(t *testing.T) {
+	for _, a := range []string{"x86", "x64", "arm", "arm64", "host"} {
+		if !validArchitectures[a] {
+			t.Errorf("validArchitectures[%q] = false, want true", a)
+		}
+	}
+	for _, a := range []string{"x86", "x64", "arm64"} {
+		if !validHostArchs[a] {
+			t.Errorf("validHostArchs[%q] = false, want true", a)
+		}
+	}
+	if validHostArchs["arm"] {
+		t.Error(`validHostArchs["arm"] = true, want false (no 32-bit ARM host toolchain exists)`)
+	}
+}
@@ -0,0 +1,23 @@
+package main
+
+import "testing"
+
+func TestRunEnvRequiresBin(t *testing.T) {
+	if code := runEnv(nil); code != 1 {
+		t.Errorf("runEnv(nil) = %d, want 1", code)
+	}
+}
+
+func TestRunEnvRejectsMissingBinDir(t *testing.T) {
+	if code := runEnv([]string{"--bin", "/nonexistent/path/for/vintner/tests"}); code != 1 {
+		t.Errorf("runEnv with a nonexistent --bin = %d, want 1", code)
+	}
+}
+
+func TestToUnixPathList(t *testing.T) {
+	got := toUnixPathList(`z:\vc\include;z:\kits\10\include`)
+	want := "/vc/include;/kits/10/include"
+	if got != want {
+		t.Errorf("toUnixPathList(...) = %q, want %q", got, want)
+	}
+}
@@ -0,0 +1,17 @@
+package main
+
+import "testing"
+
+func TestRunInstallRejectsExtraArgs(t *testing.T) {
+	if code := runInstall([]string{"one", "two"}); code != 1 {
+		t.Errorf("runInstall with two args = %d, want 1", code)
+	}
+}
+
+func TestRunInstallHelp(t *testing.T) {
+	for _, flag := range []string{"-h", "--help"} {
+		if code := runInstall([]string{flag}); code != 1 {
+			t.Errorf("runInstall([%q]) = %d, want 1", flag, code)
+		}
+	}
+}
@@ -1,9 +1,9 @@
 // Command vintner cross compiles with the real MSVC toolchain on Linux
 // via Wine. It's a multi-call binary that behaves as `cl`, `link`, `lib`,
 // `rc`, `midl`, `mt`, `dumpbin`, `msbuild`, etc. when invoked under one of
-// those names (via symlinks set up by `vintner install`), and
-// otherwise exposes the `download`/`install`/`env`/`version` management
-// subcommands.
+// those names (via symlinks set up by `vintner install`) or as
+// `vintner <tool> ...` directly (see runTool), and otherwise exposes the
+// `download`/`install`/`env`/`version` management subcommands.
 package main

 import (
@@ -24,11 +24,8 @@ func main() {
 	base := filepath.Base(os.Args[0])
 	name := strings.TrimSuffix(strings.ToLower(base), ".exe")

-	if _, ok := wrapper.Tools[name]; ok {
-		os.Exit(wrapper.Run(name, os.Args[1:]))
-	}
-	if name == "cmd" || name == "findstr" {
-		os.Exit(wrapper.Run(name, os.Args[1:]))
+	if wrapper.IsTool(name) {
+		os.Exit(wrapper.Run(name, os.Args[1:], ""))
 	}

 	os.Exit(runCLI(os.Args[1:]))
@@ -40,6 +37,10 @@ func runCLI(args []string) int {
 		return 1
 	}

+	if wrapper.IsTool(args[0]) {
+		return runTool(args[0], args[1:])
+	}
+
 	switch args[0] {
 	case "download", "dl":
 		return runDownload(args[1:])
@@ -47,8 +48,12 @@ func runCLI(args []string) int {
 		return runInstall(args[1:])
 	case "env", "e":
 		return runEnv(args[1:])
+	case "completion":
+		return runCompletion(args[1:])
+	case "doctor":
+		return runDoctor(args[1:])
 	case "version", "v", "--version":
-		fmt.Println("vintner " + version)
+		fmt.Println(versionString())
 		return 0
 	case "-h", "--help", "help", "h":
 		printUsage()
@@ -0,0 +1,30 @@
+package main
+
+import "testing"
+
+// TestRunCLIDispatch covers the subset of runCLI's switch that has no side
+// effects (no filesystem/network touched) - the actual subcommand bodies
+// (download/install/env) get their own focused tests.
+func TestRunCLIDispatch(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		args []string
+		want int
+	}{
+		{"no args prints usage", nil, 1},
+		{"unknown subcommand", []string{"frobnicate"}, 1},
+		{"help long", []string{"--help"}, 0},
+		{"help short flag", []string{"-h"}, 0},
+		{"help word", []string{"help"}, 0},
+		{"help alias", []string{"h"}, 0},
+		{"version word", []string{"version"}, 0},
+		{"version alias", []string{"v"}, 0},
+		{"version flag", []string{"--version"}, 0},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := runCLI(tc.args); got != tc.want {
+				t.Errorf("runCLI(%v) = %d, want %d", tc.args, got, tc.want)
+			}
+		})
+	}
+}
@@ -0,0 +1,22 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestDefaultToolchainDir(t *testing.T) {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		t.Skipf("no home directory available: %v", err)
+	}
+	got, err := defaultToolchainDir()
+	if err != nil {
+		t.Fatalf("defaultToolchainDir() error: %v", err)
+	}
+	want := filepath.Join(home, ".vintner")
+	if got != want {
+		t.Errorf("defaultToolchainDir() = %q, want %q", got, want)
+	}
+}
@@ -0,0 +1,40 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/Cheviiot/vintner/internal/wrapper"
+)
+
+// runTool dispatches `vintner <tool> [args...]` (cl, link, msbuild, ...)
+// directly, without needing <dest>/bin/<arch> on PATH or a same-directory
+// symlink pointing back at this binary.
+//
+// Resolves which toolchain bin dir to use from VINTNER_BIN if set (same
+// meaning as `env --bin`: point it directly at a <dest>/bin/<arch>
+// directory - useful for a non-default --dest, or to pick a specific
+// architecture when more than one is installed), else defaults to
+// <defaultToolchainDir>/bin/<hostArch>, the layout a plain `vintner
+// download && vintner install` with no --dest override produces.
+func runTool(tool string, args []string) int {
+	binDir := os.Getenv("VINTNER_BIN")
+	if binDir == "" {
+		def, err := defaultToolchainDir()
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "vintner:", err)
+			return 1
+		}
+		binDir = filepath.Join(def, "bin", detectHostArch())
+	}
+	if fi, err := os.Stat(binDir); err != nil || !fi.IsDir() {
+		fmt.Fprintf(os.Stderr,
+			"vintner: no installed toolchain found at %s\n"+
+				"Run `vintner download --accept-license && vintner install` first, "+
+				"or set VINTNER_BIN to an existing <dest>/bin/<arch> directory.\n",
+			binDir)
+		return 1
+	}
+	return wrapper.Run(tool, args, binDir)
+}
@@ -0,0 +1,24 @@
+package main
+
+import (
+	"path/filepath"
+	"testing"
+)
+
+func TestRunToolReportsMissingToolchain(t *testing.T) {
+	t.Setenv("VINTNER_BIN", filepath.Join(t.TempDir(), "does-not-exist"))
+	if code := runTool("cl", nil); code != 1 {
+		t.Errorf("runTool with a nonexistent VINTNER_BIN = %d, want 1", code)
+	}
+}
+
+func TestRunToolUsesVINTNERBinOverDefault(t *testing.T) {
+	// A directory that exists but has no env.json - past the "toolchain
+	// found at all" check, into wrapper.Run's own (already-tested)
+	// env.json-loading error path. Confirms VINTNER_BIN is actually being
+	// read and passed through, without needing a full fake toolchain.
+	t.Setenv("VINTNER_BIN", t.TempDir())
+	if code := runTool("cl", nil); code != 1 {
+		t.Errorf("runTool with an empty VINTNER_BIN dir = %d, want 1 (from the missing env.json)", code)
+	}
+}
@@ -0,0 +1,56 @@
+package main
+
+import (
+	"fmt"
+	"runtime/debug"
+)
+
+// versionString renders "vintner <version>" plus, when available, the git
+// commit and build time Go's toolchain embeds automatically (since Go
+// 1.18, `go build` stamps vcs.revision/vcs.time/vcs.modified into the
+// binary on its own - no -ldflags needed for this part, so it works the
+// same whether the binary came from CI or a plain local `go build`).
+// Knowing the exact commit a reported bug was built from, not just the
+// X.Y.Z tag, is the point: two builds of the same tag could still differ
+// if the tag was ever moved, or if someone built from an uncommitted tree.
+//
+// Note for anyone testing this: `go build` stamps vcs.* build settings,
+// but `go test` binaries don't get them - there's no environment where a
+// `go test` run can exercise the revision-formatting branch below, hence
+// formatVersion is split out and tested directly instead.
+func versionString() string {
+	revision, buildTime, dirty := "", "", false
+	if info, ok := debug.ReadBuildInfo(); ok {
+		for _, s := range info.Settings {
+			switch s.Key {
+			case "vcs.revision":
+				revision = s.Value
+			case "vcs.time":
+				buildTime = s.Value
+			case "vcs.modified":
+				dirty = s.Value == "true"
+			}
+		}
+	}
+	return formatVersion(version, revision, buildTime, dirty)
+}
+
+// formatVersion is the pure part of versionString: given a revision (full
+// git SHA, may be empty), it's shortened to 12 chars and marked "-dirty" if
+// the build tree had uncommitted changes.
+func formatVersion(ver, revision, buildTime string, dirty bool) string {
+	v := "vintner " + ver
+	if revision == "" {
+		return v
+	}
+	if len(revision) > 12 {
+		revision = revision[:12]
+	}
+	if dirty {
+		revision += "-dirty"
+	}
+	if buildTime != "" {
+		return fmt.Sprintf("%s (%s, %s)", v, revision, buildTime)
+	}
+	return fmt.Sprintf("%s (%s)", v, revision)
+}
@@ -0,0 +1,46 @@
+package main
+
+import "testing"
+
+func TestFormatVersion(t *testing.T) {
+	for _, tc := range []struct {
+		name                     string
+		ver, revision, buildTime string
+		dirty                    bool
+		want                     string
+	}{
+		{
+			name: "no VCS info at all",
+			ver:  "dev",
+			want: "vintner dev",
+		},
+		{
+			name:      "clean build with full info",
+			ver:       "0.3.0",
+			revision:  "6186837fd23616335ba8aff830801692a756799c",
+			buildTime: "2026-07-25T01:33:41Z",
+			want:      "vintner 0.3.0 (6186837fd236, 2026-07-25T01:33:41Z)",
+		},
+		{
+			name:     "dirty tree",
+			ver:      "0.3.0",
+			revision: "6186837fd23616335ba8aff830801692a756799c",
+			dirty:    true,
+			want:     "vintner 0.3.0 (6186837fd236-dirty)",
+		},
+		{
+			name:     "short revision left untouched",
+			ver:      "dev",
+			revision: "abc123",
+			want:     "vintner dev (abc123)",
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			got := formatVersion(tc.ver, tc.revision, tc.buildTime, tc.dirty)
+			if got != tc.want {
+				t.Errorf("formatVersion(%q, %q, %q, %v) = %q, want %q",
+					tc.ver, tc.revision, tc.buildTime, tc.dirty, got, tc.want)
+			}
+		})
+	}
+}
@@ -0,0 +1,94 @@
+package download
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+)
+
+// The DirectX SDK (June 2010) is the last standalone release of D3DX9 (and
+// D3DX10/11, XInput, XAudio2, ...). Microsoft never carried D3DX forward
+// into the Windows 10/11 SDK - it's deprecated in favor of D3DCompiler/
+// WICTextureLoader/DirectXTex, but plenty of legacy code (this included)
+// still links against the real d3dx9.h/d3dx9.lib. Like the WDK (see
+// wdk.go), it isn't part of the VS installer manifest or any package feed
+// vsman knows about, so this is a separate, self-contained download path
+// outside ExpandSelection/FetchPayloads/UnpackSelectedPackages.
+//
+// The installer is a self-extracting PE with an appended CAB archive.
+// cabextract (already a vintner prerequisite - see runMsiExtract's sibling
+// extractWindowsSDKPackage) unpacks it directly, without needing Wine or a
+// separate archive tool. Its -F/--filter flag (repeatable) restricts
+// extraction to the Include and Lib subtrees actually needed for building -
+// about 21MB out of the installer's 1.2GB uncompressed payload.
+
+const dxsdkURL = "https://download.microsoft.com/download/A/E/7/AE743F1F-632B-4809-87A9-AA1BB3458E31/DXSDK_Jun10.exe"
+
+// dxsdkSHA256 pins the exact installer build this code was written against
+// (verified by fully extracting it with both cabextract and 7z and cross
+// checking the file lists) - the June 2010 DirectX SDK is a frozen legacy
+// artifact Microsoft is not going to rebuild. A var, not a const, so tests
+// can point it at a small fake payload instead of the real 600MB installer.
+var dxsdkSHA256 = "705271dc83bfee54d9b94e028426e288d5f070784b7446d164f48ecfbb2a02cb"
+
+// DownloadDXSDK fetches (or reuses a cached copy of) the DirectX SDK (June
+// 2010) installer into cacheDir, then unpacks its Include and Lib trees -
+// headers and x86/x64 import libs for D3DX9/10/11, XInput, XAudio2, and the
+// rest - into destDir/DXSDK. Returns that directory.
+func DownloadDXSDK(cacheDir, destDir string) (string, error) {
+	if _, err := exec.LookPath("cabextract"); err != nil {
+		return "", fmt.Errorf("cabextract not found in PATH (install the cabextract package): %w", err)
+	}
+
+	cacheFile := filepath.Join(cacheDir, "DXSDK_Jun10.exe")
+	if !isFile(cacheFile) {
+		fmt.Println("Downloading DirectX SDK (June 2010)")
+		if err := httpDownloadFile(dxsdkURL, cacheFile); err != nil {
+			return "", fmt.Errorf("downloading DirectX SDK: %w", err)
+		}
+	} else {
+		fmt.Println("Using existing file", filepath.Base(cacheFile))
+	}
+	sum, err := sha256File(cacheFile)
+	if err != nil {
+		return "", err
+	}
+	if !equalFoldHex(sum, dxsdkSHA256) {
+		return "", fmt.Errorf("incorrect hash for downloaded file %s, aborting", filepath.Base(cacheFile))
+	}
+
+	scratch, err := os.MkdirTemp(destDir, "dxsdk-unpack-")
+	if err != nil {
+		return "", err
+	}
+	defer os.RemoveAll(scratch)
+
+	if err := runCabextract(cacheFile, scratch, "DXSDK/Include/*", "DXSDK/Lib/*"); err != nil {
+		return "", fmt.Errorf("extracting DirectX SDK: %w", err)
+	}
+
+	dxsdkDir := filepath.Join(destDir, "DXSDK")
+	if err := combineDirTrees(filepath.Join(scratch, "DXSDK"), dxsdkDir); err != nil {
+		return "", fmt.Errorf("moving DirectX SDK content into place: %w", err)
+	}
+	return dxsdkDir, nil
+}
+
+// runCabextract extracts srcFile into destDir, restricted to entries
+// matching any of patterns (cabextract's -F, repeatable, glob-matched
+// against the full in-archive path).
+func runCabextract(srcFile, destDir string, patterns ...string) error {
+	if err := os.MkdirAll(destDir, 0o755); err != nil {
+		return err
+	}
+	args := []string{"-q", "-d", destDir}
+	for _, p := range patterns {
+		args = append(args, "-F", p)
+	}
+	args = append(args, srcFile)
+	cmd := exec.Command("cabextract", args...)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
@@ -0,0 +1,111 @@
+package download
+
+import (
+	"os"
+	"path/filepath"
+	"runtime"
+	"testing"
+)
+
+// withFakeCabextract prepends a directory containing a fake "cabextract"
+// script to PATH, so tests can exercise runCabextract/DownloadDXSDK without
+// the real tool (or a real DXSDK installer) present. The fake script
+// records the arguments it was invoked with to argsFile and creates an
+// empty DXSDK/Include and DXSDK/Lib under whatever -d directory it was
+// given, mimicking a successful (if empty) extraction.
+func withFakeCabextract(t *testing.T, argsFile string) {
+	t.Helper()
+	if runtime.GOOS == "windows" {
+		t.Skip("fake cabextract script requires a POSIX shell")
+	}
+	bin := t.TempDir()
+	script := `#!/bin/sh
+echo "$@" > "` + argsFile + `"
+dest=""
+prev=""
+for a in "$@"; do
+  if [ "$prev" = "-d" ]; then
+    dest="$a"
+  fi
+  prev="$a"
+done
+mkdir -p "$dest/DXSDK/Include" "$dest/DXSDK/Lib"
+`
+	path := filepath.Join(bin, "cabextract")
+	if err := os.WriteFile(path, []byte(script), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("PATH", bin+":"+os.Getenv("PATH"))
+}
+
+func TestRunCabextractPassesFilterArgs(t *testing.T) {
+	dest := t.TempDir()
+	argsFile := filepath.Join(t.TempDir(), "args")
+	withFakeCabextract(t, argsFile)
+
+	src := filepath.Join(t.TempDir(), "installer.exe")
+	writeFile(t, src, "fake-installer-bytes")
+
+	if err := runCabextract(src, dest, "DXSDK/Include/*", "DXSDK/Lib/*"); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := os.ReadFile(argsFile)
+	if err != nil {
+		t.Fatalf("expected the fake cabextract to have run: %v", err)
+	}
+	want := "-q -d " + dest + " -F DXSDK/Include/* -F DXSDK/Lib/* " + src + "\n"
+	if string(got) != want {
+		t.Errorf("cabextract args = %q, want %q", got, want)
+	}
+}
+
+func TestDownloadDXSDKReusesCachedFileAndRejectsHashMismatch(t *testing.T) {
+	argsFile := filepath.Join(t.TempDir(), "args")
+	withFakeCabextract(t, argsFile)
+
+	cacheDir := t.TempDir()
+	destDir := t.TempDir()
+	writeFile(t, filepath.Join(cacheDir, "DXSDK_Jun10.exe"), "not the real installer")
+
+	_, err := DownloadDXSDK(cacheDir, destDir)
+	if err == nil {
+		t.Fatal("expected an error for a cached file that doesn't match dxsdkSHA256")
+	}
+	if _, statErr := os.Stat(argsFile); statErr == nil {
+		t.Error("cabextract should not have run before the hash was verified")
+	}
+}
+
+func TestDownloadDXSDKMovesExtractedContentIntoPlace(t *testing.T) {
+	argsFile := filepath.Join(t.TempDir(), "args")
+	withFakeCabextract(t, argsFile)
+
+	cacheDir := t.TempDir()
+	destDir := t.TempDir()
+	cacheFile := filepath.Join(cacheDir, "DXSDK_Jun10.exe")
+	writeFile(t, cacheFile, "fake-installer-bytes-for-hash-test")
+
+	// Patch the expected hash to match our fake cached file, since we can't
+	// (and shouldn't) fetch or embed the real 600MB installer in a test.
+	sum, err := sha256File(cacheFile)
+	if err != nil {
+		t.Fatal(err)
+	}
+	restore := dxsdkSHA256
+	dxsdkSHA256 = sum
+	defer func() { dxsdkSHA256 = restore }()
+
+	dxsdkDir, err := DownloadDXSDK(cacheDir, destDir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if dxsdkDir != filepath.Join(destDir, "DXSDK") {
+		t.Errorf("DownloadDXSDK returned %q, want %q", dxsdkDir, filepath.Join(destDir, "DXSDK"))
+	}
+	for _, sub := range []string{"Include", "Lib"} {
+		if !isDir(filepath.Join(dxsdkDir, sub)) {
+			t.Errorf("expected %s/%s to exist after extraction", dxsdkDir, sub)
+		}
+	}
+}
@@ -0,0 +1,152 @@
+package download
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func writeFile(t *testing.T, path, content string) {
+	t.Helper()
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestCombineDirTreesNonexistentSrcIsNoop(t *testing.T) {
+	dest := t.TempDir()
+	if err := combineDirTrees(filepath.Join(t.TempDir(), "does-not-exist"), dest); err != nil {
+		t.Fatalf("combineDirTrees with a nonexistent src returned an error: %v", err)
+	}
+}
+
+func TestCombineDirTreesRenamesWholesaleWhenDestMissing(t *testing.T) {
+	root := t.TempDir()
+	src := filepath.Join(root, "src")
+	dest := filepath.Join(root, "nested", "dest")
+	writeFile(t, filepath.Join(src, "file.txt"), "hello")
+
+	if err := combineDirTrees(src, dest); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.ReadFile(filepath.Join(dest, "file.txt")); err != nil {
+		t.Errorf("expected %s/file.txt to exist after combine: %v", dest, err)
+	}
+	if isDir(src) {
+		t.Error("src should have been moved (renamed), not copied")
+	}
+}
+
+func TestCombineDirTreesMergesNewSubdir(t *testing.T) {
+	root := t.TempDir()
+	src, dest := filepath.Join(root, "src"), filepath.Join(root, "dest")
+	writeFile(t, filepath.Join(src, "NewDir", "a.txt"), "a")
+	writeFile(t, filepath.Join(dest, "Existing.txt"), "keep me")
+
+	if err := combineDirTrees(src, dest); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.ReadFile(filepath.Join(dest, "NewDir", "a.txt")); err != nil {
+		t.Errorf("expected merged NewDir/a.txt: %v", err)
+	}
+	if _, err := os.ReadFile(filepath.Join(dest, "Existing.txt")); err != nil {
+		t.Errorf("pre-existing dest file was lost: %v", err)
+	}
+}
+
+func TestCombineDirTreesMergesCaseInsensitiveCollision(t *testing.T) {
+	root := t.TempDir()
+	src, dest := filepath.Join(root, "src"), filepath.Join(root, "dest")
+	// src has "Include" (capital I), dest already has "include" (lowercase) -
+	// this is exactly the MSVC/WinSDK casing-inconsistency scenario the
+	// function's doc comment describes.
+	writeFile(t, filepath.Join(src, "Include", "new.h"), "new")
+	writeFile(t, filepath.Join(dest, "include", "old.h"), "old")
+
+	if err := combineDirTrees(src, dest); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.ReadFile(filepath.Join(dest, "include", "new.h")); err != nil {
+		t.Errorf("new.h should have merged into the existing lowercase 'include' dir: %v", err)
+	}
+	if _, err := os.ReadFile(filepath.Join(dest, "include", "old.h")); err != nil {
+		t.Errorf("old.h should still be there: %v", err)
+	}
+	if isDir(filepath.Join(dest, "Include")) {
+		t.Error("a separate capital-I 'Include' dir should not have been created")
+	}
+}
+
+func TestCombineDirTreesRecursesIntoExactNameMatch(t *testing.T) {
+	root := t.TempDir()
+	src, dest := filepath.Join(root, "src"), filepath.Join(root, "dest")
+	writeFile(t, filepath.Join(src, "lib", "x64", "new.lib"), "new")
+	writeFile(t, filepath.Join(dest, "lib", "x64", "old.lib"), "old")
+
+	if err := combineDirTrees(src, dest); err != nil {
+		t.Fatal(err)
+	}
+	for _, f := range []string{"new.lib", "old.lib"} {
+		if _, err := os.ReadFile(filepath.Join(dest, "lib", "x64", f)); err != nil {
+			t.Errorf("expected lib/x64/%s to survive the merge: %v", f, err)
+		}
+	}
+}
+
+func TestCopyRedirectedAssembliesNoConfigIsNoop(t *testing.T) {
+	dir := t.TempDir()
+	app := filepath.Join(dir, "MSBuild.exe")
+	if err := CopyRedirectedAssemblies(app); err != nil {
+		t.Fatalf("with no .config file present, expected no error, got: %v", err)
+	}
+}
+
+func TestCopyRedirectedAssembliesCopiesReferencedDLL(t *testing.T) {
+	dir := t.TempDir()
+	app := filepath.Join(dir, "MSBuild.exe")
+	writeFile(t, app+".config", `<?xml version="1.0"?>
+<configuration>
+  <runtime>
+    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
+      <dependentAssembly>
+        <codeBase version="1.0.0.0" href="amd64\Some.Assembly.dll"/>
+      </dependentAssembly>
+    </assemblyBinding>
+  </runtime>
+</configuration>`)
+	writeFile(t, filepath.Join(dir, "amd64", "Some.Assembly.dll"), "binary-content")
+
+	if err := CopyRedirectedAssemblies(app); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := os.ReadFile(filepath.Join(dir, "Some.Assembly.dll"))
+	if err != nil {
+		t.Fatalf("expected Some.Assembly.dll copied next to MSBuild.exe: %v", err)
+	}
+	if string(got) != "binary-content" {
+		t.Errorf("copied file content = %q, want %q", got, "binary-content")
+	}
+}
+
+func TestCopyRedirectedAssembliesSkipsMissingTarget(t *testing.T) {
+	dir := t.TempDir()
+	app := filepath.Join(dir, "MSBuild.exe")
+	writeFile(t, app+".config", `<?xml version="1.0"?>
+<configuration>
+  <runtime>
+    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
+      <dependentAssembly>
+        <codeBase href="nowhere\Missing.dll"/>
+      </dependentAssembly>
+    </assemblyBinding>
+  </runtime>
+</configuration>`)
+
+	if err := CopyRedirectedAssemblies(app); err != nil {
+		t.Fatalf("a redirect pointing at a nonexistent file should be silently skipped, got: %v", err)
+	}
+}
@@ -84,6 +84,9 @@ func FetchPayloads(selected []*Package, cacheDir string, allowHashMismatch bool)
 func fetchOnePayloadWithRetries(payload Payload, dest, fileID string, allowHashMismatch bool) (int64, error) {
 	var lastErr error
 	for attempt := 0; attempt < maxDownloadAttempts; attempt++ {
+		if attempt > 0 {
+			time.Sleep(retryBackoff(attempt))
+		}
 		n, err := tryDownloadPayload(payload, dest, fileID, allowHashMismatch)
 		if err == nil {
 			return n, nil
@@ -94,6 +97,17 @@ func fetchOnePayloadWithRetries(payload Payload, dest, fileID string, allowHashM
 	return 0, fmt.Errorf("giving up on %s after %d attempts: %w", fileID, maxDownloadAttempts, lastErr)
 }

+// retryBackoff gives a transient failure (network blip, momentary rate
+// limiting) a little room to clear before hammering the same URL again:
+// 1s, 2s, 4s, 8s, capped at 10s.
+func retryBackoff(attempt int) time.Duration {
+	d := time.Second << uint(attempt-1)
+	if d > 10*time.Second {
+		d = 10 * time.Second
+	}
+	return d
+}
+
 func tryDownloadPayload(payload Payload, dest, fileID string, allowHashMismatch bool) (int64, error) {
 	if fi, err := os.Stat(dest); err == nil && fi.Mode().IsRegular() {
 		if payload.SHA256 != "" {
@@ -135,27 +149,63 @@ func tryDownloadPayload(payload Payload, dest, fileID string, allowHashMismatch

 var downloadHTTPClient = &http.Client{Timeout: 30 * time.Minute}

+// httpDownloadFile downloads url to dest via a dest+".part" temp file,
+// resuming from wherever a previous attempt left off if one exists - MSVC/
+// WinSDK/WDK/DXSDK payloads run into the hundreds of MB to multiple GB, so
+// restarting an interrupted download from byte 0 (a dropped connection, a
+// retry after this same function returned an error) wastes real time and
+// bandwidth on a flaky connection. Requests a byte Range starting at the
+// existing .part file's size, if any; a server that doesn't honor Range
+// (responds 200 instead of 206) gets treated as sending the whole file
+// again from byte 0, so the .part is truncated and started over rather
+// than getting byte-0 content appended onto existing bytes.
 func httpDownloadFile(url, dest string) error {
-	resp, err := downloadHTTPClient.Get(url)
+	tmp := dest + ".part"
+	var offset int64
+	if fi, err := os.Stat(tmp); err == nil {
+		offset = fi.Size()
+	}
+
+	req, err := http.NewRequest(http.MethodGet, url, nil)
+	if err != nil {
+		return err
+	}
+	if offset > 0 {
+		req.Header.Set("Range", fmt.Sprintf("bytes=%d-", offset))
+	}
+	resp, err := downloadHTTPClient.Do(req)
 	if err != nil {
 		return err
 	}
 	defer resp.Body.Close()
-	if resp.StatusCode != http.StatusOK {
+
+	var out *os.File
+	switch resp.StatusCode {
+	case http.StatusOK:
+		// No partial-content support (or nothing to resume from): the body
+		// is the whole file from byte 0.
+		out, err = os.Create(tmp)
+	case http.StatusPartialContent:
+		out, err = os.OpenFile(tmp, os.O_WRONLY|os.O_APPEND, 0o644)
+	case http.StatusRequestedRangeNotSatisfiable:
+		// Our .part is already >= the real file size - stale or corrupt.
+		// Discard it; the next retry starts clean with no Range header.
+		os.Remove(tmp)
+		return fmt.Errorf("GET %s: range not satisfiable, discarding partial download and retrying from scratch", url)
+	default:
 		return fmt.Errorf("GET %s: %s", url, resp.Status)
 	}
-	tmp := dest + ".part"
-	out, err := os.Create(tmp)
 	if err != nil {
 		return err
 	}
+
 	if _, err := io.Copy(out, resp.Body); err != nil {
 		out.Close()
-		os.Remove(tmp)
+		// Deliberately not removing tmp here: whatever bytes made it to
+		// disk are exactly what the next attempt should resume from.
 		return err
 	}
 	if err := out.Close(); err != nil {
-		os.Remove(tmp)
 		return err
 	}
 	return os.Rename(tmp, dest)
@@ -0,0 +1,173 @@
+package download
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"testing"
+)
+
+func TestHTTPDownloadFileFullDownload(t *testing.T) {
+	const body = "the quick brown fox jumps over the lazy dog"
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprint(w, body)
+	}))
+	defer srv.Close()
+
+	dest := filepath.Join(t.TempDir(), "out")
+	if err := httpDownloadFile(srv.URL, dest); err != nil {
+		t.Fatal(err)
+	}
+	got, err := os.ReadFile(dest)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != body {
+		t.Errorf("downloaded content = %q, want %q", got, body)
+	}
+}
+
+// rangeServer serves a fixed body and honors byte-range requests, exactly
+// like a real payload host (GitHub Releases, nuget.org, etc.) would.
+func rangeServer(body string) *httptest.Server {
+	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		rng := r.Header.Get("Range")
+		if rng == "" {
+			w.WriteHeader(http.StatusOK)
+			fmt.Fprint(w, body)
+			return
+		}
+		var start int
+		if _, err := fmt.Sscanf(rng, "bytes=%d-", &start); err != nil || start < 0 || start > len(body) {
+			w.WriteHeader(http.StatusRequestedRangeNotSatisfiable)
+			return
+		}
+		w.Header().Set("Content-Range", "bytes "+strconv.Itoa(start)+"-"+strconv.Itoa(len(body)-1)+"/"+strconv.Itoa(len(body)))
+		w.WriteHeader(http.StatusPartialContent)
+		fmt.Fprint(w, body[start:])
+	}))
+}
+
+func TestHTTPDownloadFileResumesFromExistingPart(t *testing.T) {
+	const body = "the quick brown fox jumps over the lazy dog"
+	srv := rangeServer(body)
+	defer srv.Close()
+
+	dest := filepath.Join(t.TempDir(), "out")
+	partial := body[:10]
+	if err := os.WriteFile(dest+".part", []byte(partial), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := httpDownloadFile(srv.URL, dest); err != nil {
+		t.Fatal(err)
+	}
+	got, err := os.ReadFile(dest)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != body {
+		t.Errorf("resumed download content = %q, want %q (partial %q should have been continued, not duplicated or lost)", got, body, partial)
+	}
+}
+
+func TestHTTPDownloadFileRestartsWhenServerIgnoresRange(t *testing.T) {
+	const body = "the quick brown fox jumps over the lazy dog"
+	// Always answers 200 with the full body, regardless of Range - some
+	// servers/CDNs genuinely don't support partial content.
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprint(w, body)
+	}))
+	defer srv.Close()
+
+	dest := filepath.Join(t.TempDir(), "out")
+	// A stale/bogus .part that must NOT end up prepended to the real
+	// content - if httpDownloadFile appended instead of truncating here,
+	// the result would start with this garbage.
+	if err := os.WriteFile(dest+".part", []byte("GARBAGE-FROM-A-STALE-ATTEMPT"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := httpDownloadFile(srv.URL, dest); err != nil {
+		t.Fatal(err)
+	}
+	got, err := os.ReadFile(dest)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != body {
+		t.Errorf("content = %q, want exactly %q (no leftover garbage prepended)", got, body)
+	}
+}
+
+func TestHTTPDownloadFileKeepsPartOnMidTransferFailure(t *testing.T) {
+	const fullBody = "0123456789"
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprint(w, fullBody[:5])
+		if f, ok := w.(http.Flusher); ok {
+			f.Flush()
+		}
+		// Simulate a dropped connection partway through by closing the
+		// underlying connection abruptly instead of finishing the body.
+		hj, ok := w.(http.Hijacker)
+		if !ok {
+			return
+		}
+		conn, _, err := hj.Hijack()
+		if err == nil {
+			conn.Close()
+		}
+	}))
+	defer srv.Close()
+
+	dest := filepath.Join(t.TempDir(), "out")
+	err := httpDownloadFile(srv.URL, dest)
+	if err == nil {
+		t.Fatal("expected an error from the truncated connection")
+	}
+
+	partial, err := os.ReadFile(dest + ".part")
+	if err != nil {
+		t.Fatalf("expected the .part file with the bytes received so far to survive a failed download: %v", err)
+	}
+	if !strings.HasPrefix(fullBody, string(partial)) || len(partial) == 0 {
+		t.Errorf(".part content = %q, want a non-empty prefix of %q", partial, fullBody)
+	}
+}
+
+func TestHTTPDownloadFileRangeNotSatisfiableDiscardsPart(t *testing.T) {
+	const body = "short"
+	srv := rangeServer(body)
+	defer srv.Close()
+
+	dest := filepath.Join(t.TempDir(), "out")
+	// .part is already longer than the real file - triggers 416 from
+	// rangeServer's own bounds check.
+	if err := os.WriteFile(dest+".part", []byte("this partial file is way too long"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := httpDownloadFile(srv.URL, dest); err == nil {
+		t.Fatal("expected an error on the first (416) attempt")
+	}
+	if _, err := os.Stat(dest + ".part"); !os.IsNotExist(err) {
+		t.Error("expected the stale .part to be discarded after a 416 response")
+	}
+
+	// The retry (a fresh caller, no Range header since .part is gone) should
+	// now succeed cleanly.
+	if err := httpDownloadFile(srv.URL, dest); err != nil {
+		t.Fatalf("retry after discarding the stale .part failed: %v", err)
+	}
+	got, err := os.ReadFile(dest)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != body {
+		t.Errorf("content = %q, want %q", got, body)
+	}
+}
@@ -0,0 +1,59 @@
+package download
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestRetryBackoff(t *testing.T) {
+	for _, tc := range []struct {
+		attempt int
+		want    time.Duration
+	}{
+		{1, 1 * time.Second},
+		{2, 2 * time.Second},
+		{3, 4 * time.Second},
+		{4, 8 * time.Second},
+		{5, 10 * time.Second}, // capped
+		{10, 10 * time.Second},
+	} {
+		if got := retryBackoff(tc.attempt); got != tc.want {
+			t.Errorf("retryBackoff(%d) = %v, want %v", tc.attempt, got, tc.want)
+		}
+	}
+}
+
+func TestSHA256File(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "f")
+	if err := os.WriteFile(path, []byte("hello"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	got, err := sha256File(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// echo -n hello | sha256sum
+	want := "2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824"
+	if got != want {
+		t.Errorf("sha256File(hello) = %q, want %q", got, want)
+	}
+}
+
+func TestEqualFoldHex(t *testing.T) {
+	for _, tc := range []struct {
+		a, b string
+		want bool
+	}{
+		{"ABCDEF", "abcdef", true},
+		{"abc123", "ABC123", true},
+		{"abc123", "abc124", false},
+		{"abc", "abcd", false},
+		{"", "", true},
+	} {
+		if got := equalFoldHex(tc.a, tc.b); got != tc.want {
+			t.Errorf("equalFoldHex(%q, %q) = %v, want %v", tc.a, tc.b, got, tc.want)
+		}
+	}
+}
@@ -198,6 +198,9 @@ const maxManifestAttempts = 5
 func httpGet(url string) ([]byte, error) {
 	var lastErr error
 	for attempt := 0; attempt < maxManifestAttempts; attempt++ {
+		if attempt > 0 {
+			time.Sleep(retryBackoff(attempt))
+		}
 		data, err := tryHTTPGet(url)
 		if err == nil {
 			return data, nil
@@ -0,0 +1,134 @@
+package download
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestPayloadName(t *testing.T) {
+	for _, tc := range []struct {
+		fileName string
+		want     string
+	}{
+		{"payload.msi", "payload.msi"},
+		{"folder/payload.msi", "payload.msi"},
+		{`folder\payload.msi`, "payload.msi"},
+		{`a\b/c\payload.msi`, "payload.msi"},
+		{"", ""},
+	} {
+		p := Payload{FileName: tc.fileName}
+		if got := p.Name(); got != tc.want {
+			t.Errorf("Payload{FileName: %q}.Name() = %q, want %q", tc.fileName, got, tc.want)
+		}
+	}
+}
+
+func TestPackageKey(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		p    Package
+		want string
+	}{
+		{"id only", Package{ID: "Foo"}, "Foo"},
+		{"id+version", Package{ID: "Foo", Version: "1.0"}, "Foo-1.0"},
+		{
+			"id+version+all arches",
+			Package{ID: "Foo", Version: "1.0", Chip: "x64", MachineArch: "x86", ProductArch: "neutral"},
+			"Foo-1.0-chip.x64-machineArch.x86-productArch.neutral",
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := tc.p.Key(); got != tc.want {
+				t.Errorf("Key() = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}
+
+func TestPackageLocalized(t *testing.T) {
+	noResources := Package{}
+	if got := noResources.Localized("en"); got != nil {
+		t.Errorf("Localized() on a package with no LocalizedResources = %v, want nil", got)
+	}
+
+	p := Package{LocalizedResources: []LocalizedResource{
+		{Language: "de-DE", Title: "Deutsch"},
+		{Language: "en-US", Title: "English"},
+		{Language: "ru-RU", Title: "Русский"},
+	}}
+
+	for _, tc := range []struct {
+		lang      string
+		wantTitle string
+	}{
+		{"ru", "Русский"},
+		{"ru-RU", "Русский"},
+		{"en", "English"},
+		{"", "English"},   // "" defaults to "en"
+		{"fr", "English"}, // no fr variant, falls back to the en-* one
+	} {
+		t.Run("lang="+tc.lang, func(t *testing.T) {
+			got := p.Localized(tc.lang)
+			if got == nil {
+				t.Fatalf("Localized(%q) = nil", tc.lang)
+			}
+			if got.Title != tc.wantTitle {
+				t.Errorf("Localized(%q).Title = %q, want %q", tc.lang, got.Title, tc.wantTitle)
+			}
+		})
+	}
+}
+
+func TestPackageSizes(t *testing.T) {
+	p := Package{
+		InstallSizes: map[string]int64{"x86": 100, "x64": 200},
+		Payloads:     []Payload{{Size: 10}, {Size: 20}, {Size: 30}},
+	}
+	if got := p.InstalledSize(); got != 300 {
+		t.Errorf("InstalledSize() = %d, want 300", got)
+	}
+	if got := p.DownloadSize(); got != 60 {
+		t.Errorf("DownloadSize() = %d, want 60", got)
+	}
+}
+
+func TestPackageDependenciesNormalizesBothShapes(t *testing.T) {
+	p := Package{DependenciesRaw: map[string]json.RawMessage{
+		"Bare.Version":    json.RawMessage(`"1.0"`),
+		"Full.Object":     json.RawMessage(`{"version":"2.0","type":"Optional","id":"Real.Target"}`),
+		"Recommended.Dep": json.RawMessage(`{"version":"3.0","type":"Recommended"}`),
+	}}
+	deps := p.Dependencies()
+
+	if d := deps["Bare.Version"]; d.Version != "1.0" || d.TargetID != "" || d.Type != "" {
+		t.Errorf("Bare.Version = %+v, want Version=1.0 TargetID='' Type=''", d)
+	}
+	if d := deps["Full.Object"]; d.Version != "2.0" || d.TargetID != "Real.Target" || d.Type != "Optional" {
+		t.Errorf("Full.Object = %+v, want Version=2.0 TargetID=Real.Target Type=Optional", d)
+	}
+	if d := deps["Recommended.Dep"]; d.Version != "3.0" || d.Type != "Recommended" {
+		t.Errorf("Recommended.Dep = %+v, want Version=3.0 Type=Recommended", d)
+	}
+
+	// Calling Dependencies() again must return the same cached map, not
+	// re-parse (and must not panic on the second call).
+	if d2 := p.Dependencies(); len(d2) != len(deps) {
+		t.Errorf("second Dependencies() call returned a different map: %v vs %v", d2, deps)
+	}
+}
+
+func TestHumanizeBytes(t *testing.T) {
+	for _, tc := range []struct {
+		size int64
+		want string
+	}{
+		{500, "500 bytes"},
+		{2048, "2.0 KB"},
+		{5 * 1024 * 1024, "5.0 MB"},
+		{2 * 1024 * 1024 * 1024, "2.0 GB"},
+	} {
+		if got := HumanizeBytes(tc.size); got != tc.want {
+			t.Errorf("HumanizeBytes(%d) = %q, want %q", tc.size, got, tc.want)
+		}
+	}
+}
@@ -16,7 +16,6 @@ var reSDKVersion = regexp.MustCompile(`^\d+\.\d+\.\d+`)
 type TriState = *bool

 func on() TriState { v := true; return &v }
-func off() TriState { v := false; return &v }

 // Options holds every flag that feeds package selection and download.
 type Options struct {
@@ -303,6 +302,7 @@ func selectSDK(opts *Options, idx Index) error {
 			}
 		}
 		if !found {
+			sort.Strings(versions)
 			return fmt.Errorf("WinSDK version %s not found (available: %s)", opts.SDKVersion, strings.Join(versions, ", "))
 		}
 	}
@@ -347,7 +347,14 @@ func collectDependencyClosure(idx Index, included map[string]bool, target string
 	included[key] = true

 	ret := []*Package{p}
-	for target, dep := range p.Dependencies() {
+	deps := p.Dependencies()
+	targets := make([]string, 0, len(deps))
+	for target := range deps {
+		targets = append(targets, target)
+	}
+	sort.Strings(targets)
+	for _, target := range targets {
+		dep := deps[target]
 		id := target
 		if dep.TargetID != "" {
 			id = dep.TargetID
@@ -193,6 +193,40 @@ func TestAggregateDependsHostArchMismatchExcludes(t *testing.T) {
 	}
 }

+// TestExpandSelectionDeterministic guards against collectDependencyClosure
+// iterating a package's dependency map directly (Go map iteration order is
+// randomized per range statement, so a regression here wouldn't necessarily
+// show up on the first run - looping catches it reliably in practice).
+func TestExpandSelectionDeterministic(t *testing.T) {
+	idx := fixtureIndex(t, "x86")
+	opts := &Options{
+		Package:         []string{"Microsoft.VisualStudio.Workload.VCTools"},
+		HostArch:        "x86",
+		OnlyHost:        true,
+		IncludeOptional: true,
+	}
+	first, err := ExpandSelection(idx, opts)
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := idsOf(first)
+	for i := 0; i < 50; i++ {
+		got, err := ExpandSelection(idx, opts)
+		if err != nil {
+			t.Fatal(err)
+		}
+		gotIDs := idsOf(got)
+		if len(gotIDs) != len(want) {
+			t.Fatalf("run %d: got %v, want %v", i, gotIDs, want)
+		}
+		for j := range want {
+			if gotIDs[j] != want[j] {
+				t.Fatalf("run %d: order changed: got %v, want %v", i, gotIDs, want)
+			}
+		}
+	}
+}
+
 func idsOf(pkgs []*Package) []string {
 	var ids []string
 	for _, p := range pkgs {
@@ -0,0 +1,118 @@
+package download
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestWDKNuGetID(t *testing.T) {
+	for _, tc := range []struct{ arch, want string }{
+		{"x64", "Microsoft.Windows.WDK.x64"},
+		{"x86", "Microsoft.Windows.WDK.x64"}, // no 32-bit package exists
+		{"arm64", "Microsoft.Windows.WDK.ARM64"},
+	} {
+		if got := WDKNuGetID(tc.arch); got != tc.want {
+			t.Errorf("WDKNuGetID(%q) = %q, want %q", tc.arch, got, tc.want)
+		}
+	}
+}
+
+func TestSDKBuildPrefix(t *testing.T) {
+	for _, tc := range []struct {
+		name     string
+		selected []*Package
+		want     string
+	}{
+		{"no SDK package", []*Package{{ID: "Something.Else"}}, ""},
+		{"win10sdk", []*Package{{ID: "Win10SDK_10.0.26100", Version: "10.0.26100.1742"}}, "10.0.26100"},
+		{"win11sdk case-insensitive id", []*Package{{ID: "WIN11SDK_10.0.22621", Version: "10.0.22621.5"}}, "10.0.22621"},
+		{"short version", []*Package{{ID: "Win10SDK_x", Version: "10.0"}}, ""},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := SDKBuildPrefix(tc.selected); got != tc.want {
+				t.Errorf("SDKBuildPrefix(...) = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}
+
+func TestFillMissingHostToolsCopiesWithoutOverwriting(t *testing.T) {
+	cDir := t.TempDir()
+	writeFile(t, filepath.Join(cDir, "bin", "10.0.26100.0", "x64", "stampinf.exe"), "x64-stampinf")
+	writeFile(t, filepath.Join(cDir, "bin", "10.0.26100.0", "x64", "inf2cat.exe"), "x64-inf2cat")
+	// x86 already ships its own real inf2cat.exe - must not be clobbered.
+	writeFile(t, filepath.Join(cDir, "bin", "10.0.26100.0", "x86", "inf2cat.exe"), "real-x86-inf2cat")
+
+	if err := fillMissingHostTools(cDir); err != nil {
+		t.Fatal(err)
+	}
+
+	x86Dir := filepath.Join(cDir, "bin", "10.0.26100.0", "x86")
+	stampinf, err := os.ReadFile(filepath.Join(x86Dir, "stampinf.exe"))
+	if err != nil {
+		t.Fatalf("expected stampinf.exe to be copied into x86: %v", err)
+	}
+	if string(stampinf) != "x64-stampinf" {
+		t.Errorf("copied stampinf.exe content = %q, want the x64 copy's content", stampinf)
+	}
+
+	inf2cat, err := os.ReadFile(filepath.Join(x86Dir, "inf2cat.exe"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(inf2cat) != "real-x86-inf2cat" {
+		t.Errorf("inf2cat.exe = %q, want the original x86 file preserved (not overwritten by the x64 copy)", inf2cat)
+	}
+}
+
+func TestFillMissingHostToolsNoBinDirIsNoop(t *testing.T) {
+	if err := fillMissingHostTools(t.TempDir()); err != nil {
+		t.Fatalf("missing bin/ dir should be a no-op, got: %v", err)
+	}
+}
+
+func TestDuplicateVersionedBuildTaskAssemblies(t *testing.T) {
+	cDir := t.TempDir()
+	buildDir := filepath.Join(cDir, "build")
+	writeFile(t, filepath.Join(buildDir, "Microsoft.DriverKit.Build.Tasks.17.0.dll"), "task-dll-bytes")
+	writeFile(t, filepath.Join(buildDir, "Microsoft.DriverKit.Build.Tasks.18.0.dll"), "already-there")
+	writeFile(t, filepath.Join(buildDir, "unrelated.dll"), "unrelated")
+
+	if err := duplicateVersionedBuildTaskAssemblies(cDir, "18.0"); err != nil {
+		t.Fatal(err)
+	}
+
+	// Already had an 18.0 copy - must not have been overwritten.
+	got, err := os.ReadFile(filepath.Join(buildDir, "Microsoft.DriverKit.Build.Tasks.18.0.dll"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != "already-there" {
+		t.Errorf("pre-existing 18.0 dll was overwritten: got %q", got)
+	}
+}
+
+func TestDuplicateVersionedBuildTaskAssembliesCreatesMissingCopy(t *testing.T) {
+	cDir := t.TempDir()
+	buildDir := filepath.Join(cDir, "build")
+	writeFile(t, filepath.Join(buildDir, "sub", "Foo.Bar.17.0.dll"), "bytes")
+
+	if err := duplicateVersionedBuildTaskAssemblies(cDir, "18.0"); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := os.ReadFile(filepath.Join(buildDir, "sub", "Foo.Bar.18.0.dll"))
+	if err != nil {
+		t.Fatalf("expected a Foo.Bar.18.0.dll duplicate: %v", err)
+	}
+	if string(got) != "bytes" {
+		t.Errorf("duplicated dll content = %q, want %q", got, "bytes")
+	}
+}
+
+func TestDuplicateVersionedBuildTaskAssembliesNoBuildDirIsNoop(t *testing.T) {
+	if err := duplicateVersionedBuildTaskAssemblies(t.TempDir(), "18.0"); err != nil {
+		t.Fatalf("missing build/ dir should be a no-op, got: %v", err)
+	}
+}
@@ -73,16 +73,22 @@ Usage:
  vintner install (i) [dir]            wire up wrappers for a downloaded MSVC
  vintner env (e) --bin <dir/bin/arch> print INCLUDE/LIB for native clang-cl/lld-link use
  vintner version (v)                  print the version
+  vintner doctor                       check wine/toolchain setup
  vintner help (h)                     show this message
+  vintner completion bash|zsh          print a shell completion script

 Run "vintner <command> --help" for that command's own options - download
-has many, including --with-wdk, --list-workloads, --list-components and
--print-deps-tree.
+has many, including --with-wdk, --with-dxsdk, --list-workloads,
+--list-components and --print-deps-tree.

 --dest/[dir] default to ~/.vintner if omitted.
 Language: set VINTNER_LANG=ru (or LANG=ru_RU...) for Russian output.
+Completion: source <(vintner completion bash)  # or zsh

-Once installed, add <dir>/bin/<arch> to PATH and invoke the tools directly:
+Once installed, add <dir>/bin/<arch> to PATH and invoke the tools directly,
+or skip PATH and run them through vintner itself - "vintner cl ...",
+"vintner msbuild ...", etc. (set VINTNER_BIN to a <dir>/bin/<arch> if it's
+not the default ~/.vintner/bin/<host-arch>):
  cl, link, lib, ml, ml64, mc, midl, mt, rc, dumpbin, msbuild, nmake, armasm, armasm64, cmd, findstr
 `,
 		RU: `vintner — кросс-компиляция настоящим MSVC на Linux через Wine
@@ -93,16 +99,23 @@ Once installed, add <dir>/bin/<arch> to PATH and invoke the tools directly:
  vintner install (i) [каталог]        настроить обёртки для скачанного MSVC
  vintner env (e) --bin <dir/bin/arch> вывести INCLUDE/LIB для clang-cl/lld-link напрямую
  vintner version (v)                  показать версию
+  vintner doctor                       проверить настройку wine/toolchain
  vintner help (h)                     показать эту справку
+  vintner completion bash|zsh          вывести скрипт автодополнения для оболочки

 Запустите «vintner <команда> --help» для параметров конкретной команды —
-у download их много, включая --with-wdk, --list-workloads, --list-components
-и --print-deps-tree.
+у download их много, включая --with-wdk, --with-dxsdk, --list-workloads,
+--list-components и --print-deps-tree.

 --dest/[каталог] по умолчанию — ~/.vintner.
 Язык: установите VINTNER_LANG=en (или LANG=en_US...) для вывода на английском.
+Можно не трогать PATH: "vintner cl ...", "vintner msbuild ..." и т.д. работают
+напрямую (VINTNER_BIN — если каталог не стандартный ~/.vintner/bin/<hostarch>).
+Автодополнение: source <(vintner completion bash)  # или zsh

-После установки добавьте <dir>/bin/<arch> в PATH и вызывайте инструменты напрямую:
+После установки добавьте <dir>/bin/<arch> в PATH и вызывайте инструменты
+напрямую, либо не трогая PATH — «vintner cl ...», «vintner msbuild ...»
+и т.д.:
  cl, link, lib, ml, ml64, mc, midl, mt, rc, dumpbin, msbuild, nmake, armasm, armasm64, cmd, findstr
 `,
 	},
@@ -120,8 +133,8 @@ Once installed, add <dir>/bin/<arch> to PATH and invoke the tools directly:
 		RU: "Каталог не указан, используется значение по умолчанию: %s",
 	},
 	"install.done": {
-		EN: "Done. Add %s to PATH to use cl, link, lib, ...",
-		RU: "Готово. Добавьте %s в PATH, чтобы использовать cl, link, lib и т.д.",
+		EN: "Done. Add %s to PATH to use cl, link, lib, ... directly, or run them as \"vintner cl\", \"vintner link\", etc. without touching PATH.",
+		RU: "Готово. Добавьте %s в PATH, чтобы использовать cl, link, lib и т.д. напрямую, либо запускайте их как «vintner cl», «vintner link» и т.д., не трогая PATH.",
 	},

 	"env.usage": {
@@ -157,6 +170,10 @@ Once installed, add <dir>/bin/<arch> to PATH and invoke the tools directly:
 		EN: "Installed WDK (%s) %s at %s\n",
 		RU: "WDK (%s) %s установлен в %s\n",
 	},
+	"download.dxsdk_installed": {
+		EN: "Installed DirectX SDK (June 2010) at %s\n",
+		RU: "DirectX SDK (июнь 2010) установлен в %s\n",
+	},
 	"download.workloads_header": {
 		EN: "Available Workloads (%d):\n",
 		RU: "Доступные рабочие нагрузки (Workload) (%d):\n",
@@ -173,4 +190,41 @@ Once installed, add <dir>/bin/<arch> to PATH and invoke the tools directly:
 		EN: "Do you accept the license? Answer \"yes\" or \"no\": ",
 		RU: "Вы принимаете лицензию? Ответьте «yes» или «no»: ",
 	},
+
+	"doctor.usage": {
+		EN: "usage: vintner doctor",
+		RU: "использование: vintner doctor",
+	},
+	"doctor.section_wine": {
+		EN: "Wine:",
+		RU: "Wine:",
+	},
+	"doctor.section_extract": {
+		EN: "Extraction tools:",
+		RU: "Инструменты распаковки:",
+	},
+	"doctor.section_toolchain": {
+		EN: "Installed toolchain:",
+		RU: "Установленный набор инструментов:",
+	},
+	"doctor.msitools_missing": {
+		EN: "msitools: not found (install the msitools package - needed by `vintner download`)",
+		RU: "msitools: не найден (установите пакет msitools — нужен для `vintner download`)",
+	},
+	"doctor.cabextract_missing": {
+		EN: "cabextract: not found (install the cabextract package - only needed for --with-wdk/--with-dxsdk)",
+		RU: "cabextract: не найден (установите пакет cabextract — нужен только для --with-wdk/--with-dxsdk)",
+	},
+	"doctor.no_toolchain": {
+		EN: "no installed toolchain found under %s (run `vintner download --accept-license && vintner install` first, or set VINTNER_BIN)",
+		RU: "установленный набор инструментов не найден в %s (сначала выполните `vintner download --accept-license && vintner install`, либо задайте VINTNER_BIN)",
+	},
+	"doctor.summary_ok": {
+		EN: "\nAll checks passed.",
+		RU: "\nВсе проверки пройдены.",
+	},
+	"doctor.summary_fail": {
+		EN: "\nSome checks failed - see [FAIL] lines above.",
+		RU: "\nНекоторые проверки не пройдены — см. строки [FAIL] выше.",
+	},
 }
@@ -0,0 +1,93 @@
+package i18n
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestDetect(t *testing.T) {
+	envKeys := []string{"VINTNER_LANG", "LC_ALL", "LC_MESSAGES", "LANG"}
+	clear := func() {
+		for _, k := range envKeys {
+			t.Setenv(k, "")
+			// t.Setenv("", "") leaves the var set-but-empty, which detect()
+			// already treats as "unset" (its loop skips v == "") - matches
+			// how a genuinely-unset env var behaves for this function.
+		}
+	}
+
+	for _, tc := range []struct {
+		name string
+		env  map[string]string
+		want Lang
+	}{
+		{"nothing set defaults to English", nil, EN},
+		{"VINTNER_LANG=ru", map[string]string{"VINTNER_LANG": "ru"}, RU},
+		{"VINTNER_LANG=en", map[string]string{"VINTNER_LANG": "en"}, EN},
+		{"VINTNER_LANG wins over a Russian LANG", map[string]string{"VINTNER_LANG": "en", "LANG": "ru_RU.UTF-8"}, EN},
+		{"LC_ALL wins over LANG", map[string]string{"LC_ALL": "ru_RU.UTF-8", "LANG": "en_US.UTF-8"}, RU},
+		{"LANG=ru_RU.UTF-8 alone", map[string]string{"LANG": "ru_RU.UTF-8"}, RU},
+		{"LANG=en_US.UTF-8 alone", map[string]string{"LANG": "en_US.UTF-8"}, EN},
+		{"unrelated locale defaults to English", map[string]string{"LANG": "de_DE.UTF-8"}, EN},
+		{"case-insensitive RU prefix", map[string]string{"VINTNER_LANG": "RU"}, RU},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			clear()
+			for k, v := range tc.env {
+				t.Setenv(k, v)
+			}
+			if got := detect(); got != tc.want {
+				t.Errorf("detect() = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}
+
+// TestCatalogCompleteness guards against adding an EN string without its RU
+// counterpart (or vice versa) - a silent gap here degrades to showing the
+// wrong language's text via T()'s EN-fallback rather than failing loudly.
+func TestCatalogCompleteness(t *testing.T) {
+	for key, entry := range catalog {
+		en, hasEN := entry[EN]
+		if !hasEN || strings.TrimSpace(en) == "" {
+			t.Errorf("catalog[%q] has no (non-empty) English translation", key)
+		}
+		ru, hasRU := entry[RU]
+		if !hasRU || strings.TrimSpace(ru) == "" {
+			t.Errorf("catalog[%q] has no (non-empty) Russian translation", key)
+		}
+	}
+}
+
+func TestTMissingKeyReturnsKeyItself(t *testing.T) {
+	got := T("no.such.key")
+	if got != "no.such.key" {
+		t.Errorf("T(unknown key) = %q, want the key itself", got)
+	}
+}
+
+func TestTFallsBackToEnglish(t *testing.T) {
+	const testKey = "test.fallback.only.en"
+	catalog[testKey] = map[Lang]string{EN: "hello %s"}
+	defer delete(catalog, testKey)
+
+	saved := current
+	current = RU
+	defer func() { current = saved }()
+
+	if got := T(testKey, "world"); got != "hello world" {
+		t.Errorf("T(%q) with no RU entry = %q, want %q", testKey, got, "hello world")
+	}
+}
+
+func TestTFormatsArgs(t *testing.T) {
+	saved := current
+	current = EN
+	defer func() { current = saved }()
+
+	got := T("download.wdk_installed", "x64", "10.0.26100.1", "/dest")
+	want := "Installed WDK (x64) 10.0.26100.1 at /dest\n"
+	if got != want {
+		t.Errorf("T(download.wdk_installed, ...) = %q, want %q", got, want)
+	}
+}
@@ -15,6 +15,7 @@ import (
 	"strings"

 	"github.com/Cheviiot/vintner/assets"
+	"github.com/Cheviiot/vintner/internal/lock"
 	"github.com/Cheviiot/vintner/internal/wineenv"
 )

@@ -34,6 +35,12 @@ func Install(dest, selfBinary string) error {
 		return fmt.Errorf("destination %q is not a directory", dest)
 	}

+	unlock, err := lock.Acquire(dest)
+	if err != nil {
+		return err
+	}
+	defer unlock()
+
 	// Targets are relative so the whole installed tree stays relocatable -
 	// moving or renaming dest doesn't break these symlinks the way an
 	// absolute target baked in at install time would.
@@ -62,6 +69,10 @@ func Install(dest, selfBinary string) error {
 		return err
 	}

+	if err := aliasPlatformToolsets(dest); err != nil {
+		return err
+	}
+
 	includeDir := filepath.Join(msvcDir, "include")
 	if err := Lowercase(includeDir, LowercaseOptions{Symlink: true}); err != nil {
 		return fmt.Errorf("lowercasing %s: %w", includeDir, err)
@@ -0,0 +1,92 @@
+package install
+
+import (
+	"os"
+	"path/filepath"
+	"regexp"
+
+	"github.com/Cheviiot/vintner/internal/wineenv"
+)
+
+var rePlatformToolsetDir = regexp.MustCompile(`^v(\d+)$`)
+
+// aliasPlatformToolsets makes every historical PlatformToolset name in
+// wineenv.KnownPlatformToolsets resolve to the one compiler `download`
+// actually fetched.
+//
+// MSBuild decides whether a PlatformToolset is "installed" at all - the
+// check behind MSB8020 - by testing whether
+// MSBuild/Microsoft/VC/v<schema>/Platforms/<arch>/PlatformToolsets/<toolset>/
+// exists on disk (Microsoft.Cpp.props, via
+// ToolLocationHelper.FindRootFolderWhereAllFilesExist). That's a plain file
+// lookup, not influenced by any environment variable - unlike the later,
+// env-var-driven VCInstallDir_<N> checks internal/wrapper's msbuildEnv
+// covers, this one needs the actual directory to exist under dest.
+// Microsoft's own downloaded MSBuild package only ships a PlatformToolsets
+// entry for the exact generation matching the fetched compiler, so any
+// project pinned to an older PlatformToolset (v142 for a project last saved
+// under VS2019, say) fails this check outright even though the one real
+// toolchain installed could easily build it.
+//
+// Toolset.props/Toolset.targets don't hardcode a version number (they just
+// import version-agnostic files like Microsoft.Cpp.MSVC.Toolset.<arch>.props),
+// so a symlink under any other historical name is a correct, transparent
+// alias rather than a divergent copy.
+func aliasPlatformToolsets(dest string) error {
+	schemaDirs, err := filepath.Glob(filepath.Join(dest, "MSBuild", "Microsoft", "VC", "v*"))
+	if err != nil {
+		return err
+	}
+	for _, schemaDir := range schemaDirs {
+		archDirs, err := filepath.Glob(filepath.Join(schemaDir, "Platforms", "*", "PlatformToolsets"))
+		if err != nil {
+			return err
+		}
+		for _, toolsetsDir := range archDirs {
+			if err := aliasOneDir(toolsetsDir); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// aliasOneDir symlinks every name in wineenv.KnownPlatformToolsets that
+// doesn't already exist in toolsetsDir onto whichever real v<N> toolset
+// subdirectory is actually present there.
+func aliasOneDir(toolsetsDir string) error {
+	entries, err := os.ReadDir(toolsetsDir)
+	if err != nil {
+		return err
+	}
+	var real string
+	for _, e := range entries {
+		if !e.IsDir() {
+			continue
+		}
+		if rePlatformToolsetDir.MatchString(e.Name()) {
+			real = e.Name()
+			break
+		}
+	}
+	if real == "" {
+		// Nothing numeric here (e.g. only the WindowsKernelModeDriver10.0-style
+		// WDK toolsets) - nothing to alias.
+		return nil
+	}
+
+	for _, n := range wineenv.KnownPlatformToolsets {
+		alias := "v" + n
+		if alias == real {
+			continue
+		}
+		aliasPath := filepath.Join(toolsetsDir, alias)
+		if exists(aliasPath) {
+			continue
+		}
+		if err := os.Symlink(real, aliasPath); err != nil {
+			return err
+		}
+	}
+	return nil
+}
@@ -0,0 +1,106 @@
+package install
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/Cheviiot/vintner/internal/wineenv"
+)
+
+func TestAliasPlatformToolsetsAliasesRealToolset(t *testing.T) {
+	dest := t.TempDir()
+	toolsetsDir := filepath.Join(dest, "MSBuild", "Microsoft", "VC", "v180", "Platforms", "x64", "PlatformToolsets")
+	realDir := filepath.Join(toolsetsDir, "v145")
+	if err := os.MkdirAll(realDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(realDir, "Toolset.props"), []byte("<Project/>"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	// A WDK toolset entry alongside it - must not be mistaken for the real
+	// numeric toolset or itself get aliased over.
+	if err := os.MkdirAll(filepath.Join(toolsetsDir, "WindowsKernelModeDriver10.0"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := aliasPlatformToolsets(dest); err != nil {
+		t.Fatalf("aliasPlatformToolsets: %v", err)
+	}
+
+	for _, n := range wineenv.KnownPlatformToolsets {
+		alias := filepath.Join(toolsetsDir, "v"+n)
+		fi, err := os.Lstat(alias)
+		if err != nil {
+			t.Errorf("expected v%s alias to exist: %v", n, err)
+			continue
+		}
+		if fi.Mode()&os.ModeSymlink == 0 {
+			t.Errorf("v%s should be a symlink, got mode %v", n, fi.Mode())
+			continue
+		}
+		target, err := os.Readlink(alias)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if target != "v145" {
+			t.Errorf("v%s symlink target = %q, want \"v145\"", n, target)
+		}
+		// Follow the alias and confirm it actually reaches the real content.
+		if !isFile(filepath.Join(toolsetsDir, "v"+n, "Toolset.props")) {
+			t.Errorf("v%s/Toolset.props not reachable through the alias", n)
+		}
+	}
+
+	if exists(filepath.Join(toolsetsDir, "WindowsKernelModeDriver10.0", "v"+wineenv.KnownPlatformToolsets[0])) {
+		t.Error("WDK toolset directory should not have been touched")
+	}
+}
+
+func TestAliasPlatformToolsetsDoesNotOverwriteExisting(t *testing.T) {
+	dest := t.TempDir()
+	toolsetsDir := filepath.Join(dest, "MSBuild", "Microsoft", "VC", "v180", "Platforms", "x64", "PlatformToolsets")
+	if err := os.MkdirAll(filepath.Join(toolsetsDir, "v145"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	// v142 already genuinely installed (e.g. a real VS install with several
+	// side-by-side toolsets) - must be left alone, not replaced with an alias.
+	real142 := filepath.Join(toolsetsDir, "v142")
+	if err := os.MkdirAll(real142, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(real142, "Toolset.props"), []byte("<!-- real v142 -->"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := aliasPlatformToolsets(dest); err != nil {
+		t.Fatalf("aliasPlatformToolsets: %v", err)
+	}
+
+	fi, err := os.Lstat(real142)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if fi.Mode()&os.ModeSymlink != 0 {
+		t.Error("pre-existing v142 directory should not have been replaced with a symlink")
+	}
+}
+
+func TestAliasPlatformToolsetsNoNumericToolset(t *testing.T) {
+	dest := t.TempDir()
+	// Only a WDK-style toolset present, nothing numeric to alias from.
+	toolsetsDir := filepath.Join(dest, "MSBuild", "Microsoft", "VC", "v180", "Platforms", "x64", "PlatformToolsets")
+	if err := os.MkdirAll(filepath.Join(toolsetsDir, "WindowsUserModeDriver10.0"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := aliasPlatformToolsets(dest); err != nil {
+		t.Fatalf("aliasPlatformToolsets: %v", err)
+	}
+
+	for _, n := range wineenv.KnownPlatformToolsets {
+		if exists(filepath.Join(toolsetsDir, "v"+n)) {
+			t.Errorf("v%s should not have been created with no real numeric toolset present", n)
+		}
+	}
+}
@@ -0,0 +1,49 @@
+// Package lock guards a destination directory against two `vintner
+// download`/`install` runs mutating it at the same time.
+package lock
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"syscall"
+)
+
+// FileName is the advisory lock file `download` and `install` both take
+// out against their (usually shared) destination directory before
+// touching anything in it - concurrent download+install, or two
+// downloads, against the same dest could otherwise interleave badly:
+// combineDirTrees' merge logic assumes it's the only thing moving files
+// into a given target at a time, and two `os.Rename` calls racing for the
+// same destination path is exactly the kind of thing that corrupts a tree
+// instead of erroring cleanly.
+const FileName = ".vintner.lock"
+
+// Acquire takes an exclusive, non-blocking lock on dest (creating dest if
+// it doesn't exist yet) and returns a func to release it, which the caller
+// must defer. If another vintner process already holds the lock, returns
+// an error immediately instead of blocking - there's no reason a second
+// invocation should silently queue up and wait for the first to finish
+// touching the same directory; the caller should simply not have started
+// it yet. Uses flock(2), so a crashed holder's lock is released
+// automatically by the kernel when its file descriptor closes - never
+// needs manual cleanup, unlike a plain "does a file exist" lock
+// convention would.
+func Acquire(dest string) (unlock func(), err error) {
+	if err := os.MkdirAll(dest, 0o755); err != nil {
+		return nil, err
+	}
+	path := filepath.Join(dest, FileName)
+	f, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0o644)
+	if err != nil {
+		return nil, err
+	}
+	if err := syscall.Flock(int(f.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); err != nil {
+		f.Close()
+		return nil, fmt.Errorf("another vintner download/install is already running against %s", dest)
+	}
+	return func() {
+		syscall.Flock(int(f.Fd()), syscall.LOCK_UN)
+		f.Close()
+	}, nil
+}
@@ -0,0 +1,124 @@
+package lock
+
+import (
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestAcquireAndRelease(t *testing.T) {
+	dest := t.TempDir()
+
+	unlock, err := Acquire(dest)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(filepath.Join(dest, FileName)); err != nil {
+		t.Errorf("expected the lock file to exist while held: %v", err)
+	}
+	unlock()
+
+	// Released - a second Acquire against the same dest must now succeed.
+	unlock2, err := Acquire(dest)
+	if err != nil {
+		t.Fatalf("Acquire after release failed: %v", err)
+	}
+	unlock2()
+}
+
+func TestAcquireCreatesDestIfMissing(t *testing.T) {
+	dest := filepath.Join(t.TempDir(), "does", "not", "exist", "yet")
+	unlock, err := Acquire(dest)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer unlock()
+	if fi, err := os.Stat(dest); err != nil || !fi.IsDir() {
+		t.Errorf("expected Acquire to create %s, stat err: %v", dest, err)
+	}
+}
+
+func TestAcquireFailsWhileAlreadyHeld(t *testing.T) {
+	dest := t.TempDir()
+
+	unlock, err := Acquire(dest)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer unlock()
+
+	if _, err := Acquire(dest); err == nil {
+		t.Fatal("expected a second Acquire against the same dest, while the first is still held, to fail")
+	}
+}
+
+func TestAcquireSucceedsAfterHolderReleases(t *testing.T) {
+	dest := t.TempDir()
+
+	unlock1, err := Acquire(dest)
+	if err != nil {
+		t.Fatal(err)
+	}
+	unlock1()
+
+	unlock2, err := Acquire(dest)
+	if err != nil {
+		t.Fatalf("Acquire should succeed once the first holder released: %v", err)
+	}
+	unlock2()
+}
+
+// TestAcquireFailsAcrossRealProcesses is the real end-to-end check: flock
+// is per-open-file-description, not per-process or per-thread, so a lock
+// held by *this* test process via one fd could in principle still be
+// re-acquirable by another fd in the same process depending on the
+// platform's exact semantics. Spawning this test binary as a genuinely
+// separate child process (via the standard TestMain re-exec trick) and
+// having it hold the lock while the parent tries to acquire it is what
+// actually proves two independent `vintner download`/`install` processes
+// contend correctly, not just two Go-level calls in one process.
+func TestAcquireFailsAcrossRealProcesses(t *testing.T) {
+	if os.Getenv("VINTNER_LOCK_TEST_HOLD") != "" {
+		unlock, err := Acquire(os.Getenv("VINTNER_LOCK_TEST_HOLD"))
+		if err != nil {
+			os.Exit(2)
+		}
+		defer unlock()
+		// Signal readiness, then wait to be killed by the parent. A plain
+		// `select {}` here would have zero other goroutines able to ever
+		// wake it, which Go's runtime provably detects as a deadlock and
+		// crashes on ("fatal error: all goroutines are asleep") - a real
+		// timer avoids that.
+		os.Stdout.WriteString("locked\n")
+		time.Sleep(time.Minute)
+	}
+
+	dest := t.TempDir()
+	exe, err := os.Executable()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cmd := exec.Command(exe, "-test.run=TestAcquireFailsAcrossRealProcesses")
+	cmd.Env = append(os.Environ(), "VINTNER_LOCK_TEST_HOLD="+dest)
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := cmd.Start(); err != nil {
+		t.Fatal(err)
+	}
+	defer cmd.Process.Kill()
+
+	buf := make([]byte, len("locked\n"))
+	if _, err := io.ReadFull(stdout, buf); err != nil || string(buf) != "locked\n" {
+		t.Fatalf("child process didn't report holding the lock: %v (%q)", err, buf)
+	}
+
+	if _, err := Acquire(dest); err == nil {
+		t.Fatal("expected Acquire to fail while a separate process holds the lock")
+	}
+}
@@ -0,0 +1,15 @@
+package wineenv
+
+// KnownPlatformToolsets are every numeric PlatformToolset short name
+// Microsoft.Cpp.Default.props has ever defined a
+// _PlatformToolsetShortNameFor_v<N> entry for (VS2013 through the VS2022
+// initial release; excludes the _xp/_wp80/_wp81 variants, which aren't
+// purely numeric). vintner only ever installs one compiler generation, but
+// real .vcxproj files in the wild are pinned to whichever generation they
+// were last edited under - v142 (VS2019) for anything not yet retargeted is
+// extremely common. Shared between internal/install (which symlinks these
+// names onto the one real MSBuild PlatformToolsets directory) and
+// internal/wrapper (which mirrors the same names onto VCInstallDir_<N>/
+// VCToolsInstallDir_<N> for the older, environment-variable-driven toolset
+// redirect chain) - see doc comments there for why both are needed.
+var KnownPlatformToolsets = []string{"90", "100", "110", "120", "140", "141", "142", "143"}
@@ -14,5 +14,5 @@ func FindWine() (string, error) {
 	if p, err := exec.LookPath("wine"); err == nil {
 		return p, nil
 	}
-	return "", fmt.Errorf("neither wine64 nor wine found in PATH")
+	return "", fmt.Errorf("neither wine64 nor wine found in PATH (install the wine package)")
 }
@@ -0,0 +1,60 @@
+package wineenv
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func fakeBinary(t *testing.T, name string) {
+	t.Helper()
+	bin := t.TempDir()
+	path := filepath.Join(bin, name)
+	if err := os.WriteFile(path, []byte("#!/bin/sh\n"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("PATH", bin)
+}
+
+func TestFindWinePrefersWine64(t *testing.T) {
+	bin := t.TempDir()
+	for _, name := range []string{"wine64", "wine"} {
+		if err := os.WriteFile(filepath.Join(bin, name), []byte("#!/bin/sh\n"), 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	t.Setenv("PATH", bin)
+
+	got, err := FindWine()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if filepath.Base(got) != "wine64" {
+		t.Errorf("FindWine() = %q, want wine64 to be preferred over wine", got)
+	}
+}
+
+func TestFindWineFallsBackToWine(t *testing.T) {
+	fakeBinary(t, "wine")
+
+	got, err := FindWine()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if filepath.Base(got) != "wine" {
+		t.Errorf("FindWine() = %q, want wine", got)
+	}
+}
+
+func TestFindWineErrorIsActionable(t *testing.T) {
+	t.Setenv("PATH", t.TempDir()) // empty dir, neither binary present
+
+	_, err := FindWine()
+	if err == nil {
+		t.Fatal("expected an error when neither wine64 nor wine is on PATH")
+	}
+	if !strings.Contains(err.Error(), "install") {
+		t.Errorf("FindWine() error = %q, want it to say what to install (matching msiextract/cabextract's error style)", err)
+	}
+}
@@ -0,0 +1,61 @@
+package wrapper
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestClPostProcessRewritesLineDirectivesInPreprocessedOutput(t *testing.T) {
+	dir := t.TempDir()
+	fi := filepath.Join(dir, "out.i")
+	// A #line directive as cl.exe's /P emits it: z:-prefixed, backslash
+	// path, doubled ("escaped") backslashes, CRLF line ending.
+	input := "#line 1 \"z:\\\\home\\\\user\\\\src\\\\hello.c\"\r\n" +
+		"int main(void) { return 0; }\r\n"
+	if err := os.WriteFile(fi, []byte(input), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	clPostProcess([]string{"/P", "/Fi" + fi, "hello.c"})
+
+	got, err := os.ReadFile(fi)
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := "#line 1 \"/home/user/src/hello.c\"\n" +
+		"int main(void) { return 0; }\n"
+	if string(got) != want {
+		t.Errorf("clPostProcess output = %q, want %q", got, want)
+	}
+}
+
+func TestClPostProcessNoopWithoutP(t *testing.T) {
+	dir := t.TempDir()
+	fi := filepath.Join(dir, "out.i")
+	original := "#line 1 \"z:\\\\foo.c\"\r\n"
+	if err := os.WriteFile(fi, []byte(original), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	// No "/P" flag - should leave the file untouched even though -Fi is present.
+	clPostProcess([]string{"/Fi" + fi, "foo.c"})
+
+	got, err := os.ReadFile(fi)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != original {
+		t.Errorf("file was modified without /P: got %q, want unchanged %q", got, original)
+	}
+}
+
+func TestClPostProcessNoopWithoutFi(t *testing.T) {
+	// Must not panic or error when -Fi wasn't passed - just silently skip.
+	clPostProcess([]string{"/P", "foo.c"})
+}
+
+func TestClPostProcessMissingFileIsSilent(t *testing.T) {
+	// The referenced -Fi file doesn't exist - clPostProcess must not panic.
+	clPostProcess([]string{"/P", "/Fi" + filepath.Join(t.TempDir(), "missing.i"), "foo.c"})
+}
@@ -29,7 +29,28 @@ func msbuildEnv(cfg *wineenv.Config, paths *wineenv.Paths) map[string]string {
 		// tools onto the same UTC clock removes the mismatch.
 		"TZ": "UTC",

+		// VCToolsVersion must be a real version string, not left unset:
+		// Microsoft.Cpp.VCTools.props itself falls back to the literal
+		// placeholder "VCToolsVersion_is_not_defined" whenever it's empty,
+		// and that placeholder then reaches unconditional (not gated behind
+		// CheckMSVCComponents) version-string comparisons elsewhere in
+		// Microsoft.CppBuild.targets, e.g. the SegmentHeap manifest check's
+		// VersionGreaterThanOrEquals(), which throws MSB4184 on a
+		// non-version string.
+		//
+		// CheckMSVCComponents=false is what actually makes an aliased
+		// PlatformToolset safe to combine with that real version: without
+		// it, CheckVCToolsetVersion (Microsoft.CppBuild.targets, MSB8052)
+		// rejects the combination whenever VCToolsVersion's numeric
+		// generation doesn't match PlatformToolset's - exactly the legacy-
+		// project case toolsetSuffixes/aliasPlatformToolsets exist for (a
+		// v142 project against the one real, newer compiler actually
+		// installed). Everything else CheckMSVCComponents gates
+		// (Microsoft.CppBuild.targets ~495-535) is diagnostic-only - MFC/ATL/
+		// Spectre component presence warnings, none of it feeding into the
+		// actual compile/link - so disabling it costs nothing here.
 		"DisableRegistryUse":  "true",
+		"CheckMSVCComponents": "false",
 		"VCToolsVersion":      cfg.MSVCVer,
 		"VsInstallRoot":       paths.BaseWin + `\`,
 		"VSInstallDir":        paths.BaseWin + `\`,
@@ -58,20 +79,29 @@ func msbuildEnv(cfg *wineenv.Config, paths *wineenv.Paths) map[string]string {
 		"Platform": msbuildPlatform(cfg.Arch),
 	}

-	// Microsoft.Cpp.props resolves the compiler/toolset location through
-	// VCInstallDir_<N>/VCToolsInstallDir_<N>, where <N> is whatever numeric
-	// suffix the installed MSBuild toolset property sheets use (e.g.
-	// .../MSBuild/Microsoft/VC/v180 -> "180"). Populate every one actually
-	// present, so a project pinned to any of them resolves to the one real
-	// toolchain that's installed.
-	matches, _ := filepath.Glob(filepath.Join(paths.BaseUnix, "MSBuild", "Microsoft", "VC", "v*"))
-	for _, m := range matches {
-		sub := reToolsetDir.FindStringSubmatch(filepath.Base(m))
-		if sub == nil {
-			continue
-		}
-		env["VCInstallDir_"+sub[1]] = paths.MSVCBaseWin + `\`
-		env["VCToolsInstallDir_"+sub[1]] = paths.MSVCDirWin + `\`
+	// VCInstallDir_<N>/VCToolsInstallDir_<N> are consulted under two
+	// completely different numbering schemes, both needing the single real
+	// toolchain behind every <N> they might ask for:
+	//
+	//  - Microsoft.Cpp.Default.props keys its early "is this toolset even
+	//    installed" check (the one MSB8020 comes from) off <N> = the
+	//    PlatformToolset suffix a .vcxproj actually declares (v142, v143,
+	//    v145, ...) - the same short name Microsoft stamps on
+	//    VC/Auxiliary/Build/Microsoft.VCToolsVersion.v<N>.default.props for
+	//    the downloaded compiler.
+	//  - Microsoft.CppBuild.targets (MSB8070) instead keys off <N> = the
+	//    MSBuild targets-schema version whose Microsoft.Cpp.props ended up
+	//    imported for this run (MSBuild/Microsoft/VC/v150|v160|v170|v180 -
+	//    fixed, shipped identically with every MSBuild release, unrelated to
+	//    which compiler is installed), to locate the specific toolset
+	//    version subfolder.
+	//
+	// Populate every <N> from both sources, all pointing at the one real
+	// toolchain that's installed, so a project pinned to any PlatformToolset
+	// resolves at every stage MSBuild checks it.
+	for _, n := range toolsetSuffixes(paths.BaseUnix) {
+		env["VCInstallDir_"+n] = paths.MSVCBaseWin + `\`
+		env["VCToolsInstallDir_"+n] = paths.MSVCDirWin + `\`
 	}

 	if strings.HasSuffix(paths.MSBuildBinDir, "amd64") {
@@ -94,6 +124,133 @@ func msbuildEnv(cfg *wineenv.Config, paths *wineenv.Paths) map[string]string {
 	return env
 }

+// toolsetSuffixes collects every numeric <N> that either VCInstallDir_<N>
+// lookup mechanism (see msbuildEnv) might be asked to resolve for this
+// installation: PlatformToolset short names from
+// vc/Auxiliary/Build/Microsoft.VCToolsVersion.v<N>.default.props, MSBuild
+// targets-schema versions from MSBuild/Microsoft/VC/v<N>, and every
+// historical PlatformToolset name (see wineenv.KnownPlatformToolsets) - a
+// project pinned to any of them all resolves to the one real toolchain
+// installed.
+func toolsetSuffixes(baseUnix string) []string {
+	seen := map[string]bool{}
+	var suffixes []string
+
+	record := func(n string) {
+		if seen[n] {
+			return
+		}
+		seen[n] = true
+		suffixes = append(suffixes, n)
+	}
+
+	add := func(dir, prefix, suffix string) {
+		matches, _ := filepath.Glob(filepath.Join(dir, "*"))
+		for _, m := range matches {
+			name := filepath.Base(m)
+			if prefix != "" {
+				if !strings.HasPrefix(name, prefix) {
+					continue
+				}
+				name = strings.TrimPrefix(name, prefix)
+			}
+			name = strings.TrimSuffix(name, suffix)
+			sub := reToolsetDir.FindStringSubmatch(name)
+			if sub == nil {
+				continue
+			}
+			record(sub[1])
+		}
+	}
+
+	add(filepath.Join(baseUnix, "vc", "Auxiliary", "Build"), "Microsoft.VCToolsVersion.", ".default.props")
+	add(filepath.Join(baseUnix, "MSBuild", "Microsoft", "VC"), "", "")
+	for _, n := range wineenv.KnownPlatformToolsets {
+		record(n)
+	}
+
+	return suffixes
+}
+
+// reGlobalProp matches an MSBuild global-property command-line switch
+// ("/p:Name=...", "-property:Name=...", case-insensitive on both the
+// -p/-property spelling and the property name) so msbuildGlobalArgs can tell
+// whether the caller already pinned a given property themselves.
+func reGlobalProp(name string) *regexp.Regexp {
+	return regexp.MustCompile(`(?i)^[-/](p|property):` + regexp.QuoteMeta(name) + `=`)
+}
+
+// msbuildGlobalArgs returns /p: switches to prepend to an MSBuild invocation,
+// one per forced property not already present in args.
+//
+// WindowsTargetPlatformVersion is the one property that needs this rather
+// than an env var: unlike VCInstallDir_<N> (an input to a props-file
+// *lookup*, so any value msbuildEnv sets is visible no matter what a project
+// pins its PlatformToolset to), WindowsTargetPlatformVersion is itself the
+// value most legacy .vcxproj files hardcode directly in a PropertyGroup -
+// and an explicit PropertyGroup assignment always wins over an inherited
+// environment variable of the same name. A command-line global property is
+// the one thing a project file can't override, which is exactly what's
+// needed here: vintner only ever installs one Windows SDK version, so - same
+// reasoning as the PlatformToolset fallback above - any project should
+// transparently build against that one installed version rather than fail
+// outright over an exact version string it happened to be pinned to when
+// last saved from a real Windows SDK selector dropdown.
+func msbuildGlobalArgs(cfg *wineenv.Config, args []string) []string {
+	forced := map[string]string{
+		"WindowsTargetPlatformVersion": cfg.SDKVer,
+	}
+
+	var out []string
+	for name, value := range forced {
+		re := reGlobalProp(name)
+		alreadySet := false
+		for _, a := range args {
+			if re.MatchString(a) {
+				alreadySet = true
+				break
+			}
+		}
+		if !alreadySet {
+			out = append(out, "/p:"+name+"="+value)
+		}
+	}
+	return out
+}
+
+var reNodeReuse = regexp.MustCompile(`(?i)^[-/](nodereuse|nr):`)
+
+// msbuildNodeReuseArgs returns ["/nodeReuse:false"] unless args already pins
+// node reuse one way or the other.
+//
+// MSBuild's node-reuse worker processes (its own /nodeReuse:true default)
+// don't behave like a normal child process here: they're meant to outlive
+// the parent msbuild.exe invocation that spawned them, waiting around under
+// Wine for the *next* msbuild call to reuse them - so nothing about
+// vintner's own process-lifetime handling (see signals.go) touches them,
+// and there's no parent process left to notice if one wedges. If a build is
+// interrupted (Ctrl-C, a killed session, a crashed Wine transport) mid-
+// compile, the worker can be left holding a half-open pipe/mutex,
+// permanently deadlocked rather than exited - confirmed in practice: a
+// stale reused node kept throwing an unrelated-looking
+// `System.TypeLoadException` on Microsoft.VisualStudio.Telemetry on every
+// subsequent build, for hours, until it was killed by hand and the next
+// build got a fresh node. Forcing node reuse off means every invocation
+// gets a clean process, so a wedged one can never poison a later,
+// unrelated build - at the cost of the couple-hundred-ms/node startup time
+// node reuse exists to save. Callers who deliberately want reuse (e.g.
+// running many builds back to back and are prepared to clean up wedged
+// nodes themselves) can still pass their own /nodeReuse or /nr switch to
+// override this.
+func msbuildNodeReuseArgs(args []string) []string {
+	for _, a := range args {
+		if reNodeReuse.MatchString(a) {
+			return nil
+		}
+	}
+	return []string{"/nodeReuse:false"}
+}
+
 func msbuildPlatform(arch string) string {
 	switch arch {
 	case "x86":
@@ -0,0 +1,222 @@
+package wrapper
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/Cheviiot/vintner/internal/wineenv"
+)
+
+func TestMsbuildPlatform(t *testing.T) {
+	for _, tc := range []struct{ arch, want string }{
+		{"x86", "Win32"},
+		{"x64", "x64"},
+		{"arm", "ARM"},
+		{"arm64", "ARM64"},
+	} {
+		if got := msbuildPlatform(tc.arch); got != tc.want {
+			t.Errorf("msbuildPlatform(%q) = %q, want %q", tc.arch, got, tc.want)
+		}
+	}
+}
+
+func newTestPaths(t *testing.T, cfg *wineenv.Config) (*wineenv.Paths, string) {
+	t.Helper()
+	base := t.TempDir()
+	return wineenv.NewPaths(cfg, base), base
+}
+
+func TestMsbuildEnvBasics(t *testing.T) {
+	cfg := &wineenv.Config{Arch: "x64", Host: "x64", DotnetHost: "amd64", MSVCVer: "14.51.36231", SDKVer: "10.0.26100.0"}
+	paths, _ := newTestPaths(t, cfg)
+
+	env := msbuildEnv(cfg, paths)
+
+	if env["TZ"] != "UTC" {
+		t.Errorf(`env["TZ"] = %q, want "UTC"`, env["TZ"])
+	}
+	if env["DisableRegistryUse"] != "true" {
+		t.Errorf(`env["DisableRegistryUse"] = %q, want "true"`, env["DisableRegistryUse"])
+	}
+	if env["CheckMSVCComponents"] != "false" {
+		t.Errorf(`env["CheckMSVCComponents"] = %q, want "false" (else CheckVCToolsetVersion errors on an aliased PlatformToolset)`, env["CheckMSVCComponents"])
+	}
+	// VCToolsVersion must be a real version string (see msbuildEnv's doc
+	// comment on it: leaving it unset makes Microsoft.Cpp.VCTools.props
+	// substitute a placeholder that then breaks unconditional version
+	// comparisons elsewhere). CheckMSVCComponents=false is what keeps this
+	// safe to combine with an aliased PlatformToolset.
+	if env["VCToolsVersion"] != cfg.MSVCVer {
+		t.Errorf(`env["VCToolsVersion"] = %q, want %q`, env["VCToolsVersion"], cfg.MSVCVer)
+	}
+	if env["WindowsTargetPlatformVersion"] != cfg.SDKVer {
+		t.Errorf(`env["WindowsTargetPlatformVersion"] = %q, want %q`, env["WindowsTargetPlatformVersion"], cfg.SDKVer)
+	}
+	if env["Platform"] != "x64" {
+		t.Errorf(`env["Platform"] = %q, want "x64"`, env["Platform"])
+	}
+	if env["SignMode"] != "off" {
+		t.Errorf(`env["SignMode"] = %q, want "off" (driver builds must not attempt real signing)`, env["SignMode"])
+	}
+	// No WDK content on disk in this test - must not claim otherwise.
+	if _, ok := env["WDKContentRoot"]; ok {
+		t.Error(`env["WDKContentRoot"] set even though no wdk/<arch>/c directory exists`)
+	}
+}
+
+func TestMsbuildEnvDiscoversEveryToolsetVersion(t *testing.T) {
+	cfg := &wineenv.Config{Arch: "x64", Host: "x64", DotnetHost: "amd64", MSVCVer: "14.51.36231", SDKVer: "10.0.26100.0"}
+	paths, base := newTestPaths(t, cfg)
+
+	// Real layout has two independent sources feeding VCInstallDir_<N>/
+	// VCToolsInstallDir_<N> (see toolsetSuffixes' doc comment for why both
+	// are needed): the PlatformToolset short names a downloaded compiler
+	// ships default-props for, and MSBuild's own fixed schema-version dirs.
+	buildDir := filepath.Join(base, "vc", "Auxiliary", "Build")
+	if err := os.MkdirAll(buildDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	for _, name := range []string{
+		"Microsoft.VCToolsVersion.v145.default.props",
+		"Microsoft.VCToolsVersion.v143.default.props",
+		"Microsoft.VCToolsVersion.default.props", // no version suffix - must not match
+	} {
+		if err := os.WriteFile(filepath.Join(buildDir, name), nil, 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, v := range []string{"v180", "not-a-version"} {
+		if err := os.MkdirAll(filepath.Join(base, "MSBuild", "Microsoft", "VC", v), 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	env := msbuildEnv(cfg, paths)
+
+	for _, n := range []string{"145", "143", "180"} {
+		if _, ok := env["VCInstallDir_"+n]; !ok {
+			t.Errorf("expected VCInstallDir_%s to be set", n)
+		}
+		if _, ok := env["VCToolsInstallDir_"+n]; !ok {
+			t.Errorf("expected VCToolsInstallDir_%s to be set", n)
+		}
+	}
+	if _, ok := env["VCInstallDir_not-a-version"]; ok {
+		t.Error("a directory not matching v<digits> should not have produced a VCInstallDir_ entry")
+	}
+}
+
+func TestToolsetSuffixesDedupsOverlap(t *testing.T) {
+	base := t.TempDir()
+	buildDir := filepath.Join(base, "vc", "Auxiliary", "Build")
+	if err := os.MkdirAll(buildDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(buildDir, "Microsoft.VCToolsVersion.v180.default.props"), nil, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.MkdirAll(filepath.Join(base, "MSBuild", "Microsoft", "VC", "v180"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+
+	got := toolsetSuffixes(base)
+	count := 0
+	for _, n := range got {
+		if n == "180" {
+			count++
+		}
+	}
+	if count != 1 {
+		t.Errorf("toolsetSuffixes() returned %q with %d entries for \"180\" (from both sources), want exactly 1", got, count)
+	}
+}
+
+func TestMsbuildGlobalArgsForcesWindowsTargetPlatformVersion(t *testing.T) {
+	cfg := &wineenv.Config{SDKVer: "10.0.26100.0"}
+
+	got := msbuildGlobalArgs(cfg, []string{"Foo.sln", "/p:Configuration=Release"})
+	want := "/p:WindowsTargetPlatformVersion=10.0.26100.0"
+	found := false
+	for _, a := range got {
+		if a == want {
+			found = true
+		}
+	}
+	if !found {
+		t.Errorf("msbuildGlobalArgs(...) = %v, want it to contain %q", got, want)
+	}
+}
+
+func TestMsbuildGlobalArgsRespectsExplicitOverride(t *testing.T) {
+	cfg := &wineenv.Config{SDKVer: "10.0.26100.0"}
+
+	for _, explicit := range []string{
+		"/p:WindowsTargetPlatformVersion=10.0.19041.0",
+		"-p:WindowsTargetPlatformVersion=10.0.19041.0",
+		"/property:WindowsTargetPlatformVersion=10.0.19041.0",
+	} {
+		got := msbuildGlobalArgs(cfg, []string{"Foo.sln", explicit})
+		for _, a := range got {
+			if reGlobalProp("WindowsTargetPlatformVersion").MatchString(a) {
+				t.Errorf("msbuildGlobalArgs with explicit %q also injected %q - should have left the caller's value alone", explicit, a)
+			}
+		}
+	}
+}
+
+func TestMsbuildEnvDetectsWDKContentRoot(t *testing.T) {
+	cfg := &wineenv.Config{Arch: "x64", Host: "x64", DotnetHost: "amd64", MSVCVer: "14.51.36231", SDKVer: "10.0.26100.0"}
+	paths, base := newTestPaths(t, cfg)
+
+	if err := os.MkdirAll(filepath.Join(base, "wdk", "x64", "c"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+
+	env := msbuildEnv(cfg, paths)
+
+	if env["WDKContentRoot"] == "" {
+		t.Error("expected WDKContentRoot to be set once wdk/x64/c exists on disk")
+	}
+	if env["WDKBuildFolder"] != cfg.SDKVer {
+		t.Errorf(`env["WDKBuildFolder"] = %q, want %q`, env["WDKBuildFolder"], cfg.SDKVer)
+	}
+}
+
+func TestMsbuildEnvPreferredToolArchitecture(t *testing.T) {
+	// PreferredToolArchitecture should only be set when the host toolset
+	// bin dir is the 64-bit ("amd64") .NET host - not for arm64.
+	cfg64 := &wineenv.Config{Arch: "x64", Host: "x64", DotnetHost: "amd64", MSVCVer: "1", SDKVer: "1"}
+	paths64, _ := newTestPaths(t, cfg64)
+	if env := msbuildEnv(cfg64, paths64); env["PreferredToolArchitecture"] != "x64" {
+		t.Errorf(`with DotnetHost=amd64, PreferredToolArchitecture = %q, want "x64"`, env["PreferredToolArchitecture"])
+	}
+
+	cfgARM := &wineenv.Config{Arch: "arm64", Host: "arm64", DotnetHost: "arm64", MSVCVer: "1", SDKVer: "1"}
+	pathsARM, _ := newTestPaths(t, cfgARM)
+	if env := msbuildEnv(cfgARM, pathsARM); env["PreferredToolArchitecture"] != "" {
+		t.Errorf(`with DotnetHost=arm64, PreferredToolArchitecture = %q, want unset`, env["PreferredToolArchitecture"])
+	}
+}
+
+func TestMsbuildNodeReuseArgsForcesOffByDefault(t *testing.T) {
+	got := msbuildNodeReuseArgs([]string{"Foo.sln", "/p:Configuration=Release"})
+	want := []string{"/nodeReuse:false"}
+	if len(got) != 1 || got[0] != want[0] {
+		t.Errorf("msbuildNodeReuseArgs(...) = %v, want %v", got, want)
+	}
+}
+
+func TestMsbuildNodeReuseArgsRespectsExplicitOverride(t *testing.T) {
+	for _, explicit := range []string{
+		"/nodeReuse:true",
+		"-nodeReuse:true",
+		"/nr:true",
+		"/NODEREUSE:FALSE", // caller explicitly wanting it off too - still shouldn't double up
+	} {
+		got := msbuildNodeReuseArgs([]string{"Foo.sln", explicit})
+		if got != nil {
+			t.Errorf("msbuildNodeReuseArgs with explicit %q = %v, want nil (left alone)", explicit, got)
+		}
+	}
+}
@@ -1,6 +1,7 @@
 package wrapper

 import (
+	"fmt"
 	"os"
 	"os/exec"
 )
@@ -25,11 +26,21 @@ func execInherit(args []string) int {
 	if len(args) == 0 {
 		return 0
 	}
-	cmd := exec.Command(args[0], args[1:]...)
-	cmd.Stdin = os.Stdin
-	cmd.Stdout = os.Stdout
-	cmd.Stderr = os.Stderr
-	if err := cmd.Run(); err != nil {
+	tc, cleanup := newToolCommand(args[0], args[1:]...)
+	defer cleanup()
+	tc.Stdin = os.Stdin
+	tc.Stdout = os.Stdout
+	tc.Stderr = os.Stderr
+	if err := tc.Start(); err != nil {
+		return 127
+	}
+	stopSignals := forwardSignals(tc.Process)
+	defer stopSignals()
+	if err := tc.Wait(); err != nil {
+		if tc.timedOut() {
+			fmt.Fprintln(os.Stderr, tc.timeoutMessage())
+			return 124
+		}
 		if exitErr, ok := err.(*exec.ExitError); ok {
 			return exitErr.ExitCode()
 		}
@@ -30,7 +30,15 @@ const toolRelayName = "toolrelay.exe"

 // Run executes the named multi-call tool with args, exactly as the original
 // bash wrappers would, and returns the process exit code.
-func Run(tool string, args []string) int {
+//
+// binDir is the <dest>/bin/<arch> directory holding env.json for this
+// invocation. Pass "" for the ordinary multi-call case (invoked as `cl`,
+// `link`, etc. via a same-directory symlink) to have it resolved from the
+// running binary's own location; a non-empty value is for `vintner <tool>
+// ...` direct dispatch (see cmd/vintner's runTool), which isn't running
+// from inside any particular <dest>/bin/<arch> and so has nothing to
+// resolve on its own.
+func Run(tool string, args []string, binDir string) int {
 	if nativeTools[tool] {
 		return runNative(tool, args)
 	}
@@ -41,19 +49,23 @@ func Run(tool string, args []string) int {
 		return 127
 	}

+	scriptDir := binDir
+	if scriptDir == "" {
 		// os.Executable() (backed by /proc/self/exe on Linux) fully resolves
-	// symlinks, unlike os.Args[0]: not every shell passes a PATH-resolved
-	// absolute path as argv[0] (some just pass the bare command name), which
-	// would make an argv[0]-based lookup resolve against the caller's cwd
-	// instead of the actual install dir. `install` sets each arch dir up
-	// with its own local copy of the binary precisely so this resolves to
-	// <dest>/bin/<arch>, not <dest>/bin.
+		// symlinks, unlike os.Args[0]: not every shell passes a
+		// PATH-resolved absolute path as argv[0] (some just pass the bare
+		// command name), which would make an argv[0]-based lookup resolve
+		// against the caller's cwd instead of the actual install dir.
+		// `install` sets each arch dir up with its own local copy of the
+		// binary precisely so this resolves to <dest>/bin/<arch>, not
+		// <dest>/bin.
 		exePath, err := os.Executable()
 		if err != nil {
 			fmt.Fprintln(os.Stderr, "vintner:", err)
 			return 1
 		}
-	scriptDir := filepath.Dir(exePath)
+		scriptDir = filepath.Dir(exePath)
+	}

 	cfg, err := wineenv.Load(scriptDir)
 	if err != nil {
@@ -83,24 +95,30 @@ func Run(tool string, args []string) int {
 		// MSBuild: skip all filtering/toolrelay (its output is meant to be
 		// read as-is), and add the extra environment MSBuild's own
 		// toolset/SDK-detection props need on top of the generic
-		// INCLUDE/LIB/WINEPATH.
-		cmd := exec.Command(wineBin, append([]string{toolExePath}, rewritten...)...)
+		// INCLUDE/LIB/WINEPATH, plus any global properties a project file
+		// itself could otherwise override (see msbuildGlobalArgs) and a
+		// forced /nodeReuse:false (see msbuildNodeReuseArgs).
+		msArgs := append(msbuildGlobalArgs(cfg, rewritten), rewritten...)
+		msArgs = append(msbuildNodeReuseArgs(rewritten), msArgs...)
+		tc, cleanup := newToolCommand(wineBin, append([]string{toolExePath}, msArgs...)...)
+		defer cleanup()
 		env := buildEnv(paths)
 		for k, v := range msbuildEnv(cfg, paths) {
 			env = append(env, k+"="+v)
 		}
-		cmd.Env = env
-		cmd.Stdin = os.Stdin
-		exitCode = runRawStdout(cmd)
+		tc.Env = env
+		tc.Stdin = os.Stdin
+		exitCode = runRawStdout(tc)
 	default:
 		relay := filepath.Join(paths.BaseUnix, "bin", toolRelayName)
 		if fi, err := os.Stat(relay); err == nil && !fi.IsDir() {
 			exitCode = runViaToolRelay(wineBin, relay, toolExePath, rewritten, paths, s.stdoutFilter, s.stderrFilter)
 		} else {
-			cmd := exec.Command(wineBin, append([]string{toolExePath}, rewritten...)...)
-			cmd.Env = buildEnv(paths)
-			cmd.Stdin = os.Stdin
-			exitCode = runFiltered(cmd, s.stdoutFilter, s.stderrFilter)
+			tc, cleanup := newToolCommand(wineBin, append([]string{toolExePath}, rewritten...)...)
+			defer cleanup()
+			tc.Env = buildEnv(paths)
+			tc.Stdin = os.Stdin
+			exitCode = runFiltered(tc, s.stdoutFilter, s.stderrFilter)
 		}
 	}

@@ -135,18 +153,21 @@ func runViaToolRelay(wineBin, relayExe, exePath string, args []string, paths *wi
 	defer os.Remove(stderrFifo)

 	cmdArgs := append([]string{relayExe, exePath}, args...)
-	cmd := exec.Command(wineBin, cmdArgs...)
-	cmd.Env = append(buildEnv(paths), "MSVCGOWINE_STDOUT="+stdoutFifo, "MSVCGOWINE_STDERR="+stderrFifo)
+	tc, cleanup := newToolCommand(wineBin, cmdArgs...)
+	defer cleanup()
+	tc.Env = append(buildEnv(paths), "MSVCGOWINE_STDOUT="+stdoutFifo, "MSVCGOWINE_STDERR="+stderrFifo)
 	if devNull, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0); err == nil {
 		defer devNull.Close()
-		cmd.Stdout = devNull
-		cmd.Stderr = devNull
+		tc.Stdout = devNull
+		tc.Stderr = devNull
 	}

-	if err := cmd.Start(); err != nil {
+	if err := tc.Start(); err != nil {
 		fmt.Fprintln(os.Stderr, "vintner:", err)
 		return 1
 	}
+	stopSignals := forwardSignals(tc.Process)
+	defer stopSignals()

 	var wg sync.WaitGroup
 	wg.Add(2)
@@ -169,10 +190,14 @@ func runViaToolRelay(wineBin, relayExe, exePath string, args []string, paths *wi
 		pumpLines(f, os.Stderr, stderrF)
 	}()

-	err := cmd.Wait()
+	err := tc.Wait()
 	wg.Wait()

 	if err != nil {
+		if tc.timedOut() {
+			fmt.Fprintln(os.Stderr, tc.timeoutMessage())
+			return 124
+		}
 		if exitErr, ok := err.(*exec.ExitError); ok {
 			return exitErr.ExitCode()
 		}
@@ -188,33 +213,39 @@ func runViaToolRelay(wineBin, relayExe, exePath string, args []string, paths *wi
 // own copy goroutines - not the caller's terminal or pipe - are exposed to
 // Wine's background processes holding those descriptors open; see
 // pipeDrainGrace.
-func runRawStdout(cmd *exec.Cmd) int {
-	stdout, err := cmd.StdoutPipe()
+func runRawStdout(tc *toolCommand) int {
+	stdout, err := tc.StdoutPipe()
 	if err != nil {
 		fmt.Fprintln(os.Stderr, "vintner:", err)
 		return 1
 	}
-	stderr, err := cmd.StderrPipe()
+	stderr, err := tc.StderrPipe()
 	if err != nil {
 		fmt.Fprintln(os.Stderr, "vintner:", err)
 		return 1
 	}

-	if err := cmd.Start(); err != nil {
+	if err := tc.Start(); err != nil {
 		fmt.Fprintln(os.Stderr, "vintner:", err)
 		return 1
 	}
+	stopSignals := forwardSignals(tc.Process)
+	defer stopSignals()

 	doneOut := make(chan struct{})
 	doneErr := make(chan struct{})
 	go func() { io.Copy(os.Stdout, stdout); close(doneOut) }()
 	go func() { io.Copy(os.Stderr, stderr); close(doneErr) }()

-	err = cmd.Wait()
+	err = tc.Wait()
 	drain(doneOut)
 	drain(doneErr)

 	if err != nil {
+		if tc.timedOut() {
+			fmt.Fprintln(os.Stderr, tc.timeoutMessage())
+			return 124
+		}
 		if exitErr, ok := err.(*exec.ExitError); ok {
 			return exitErr.ExitCode()
 		}
@@ -262,33 +293,39 @@ func buildEnv(p *wineenv.Paths) []string {

 // runFiltered streams stdout/stderr line by line through the tool's
 // filters (CR-stripping always applied first), then waits for completion.
-func runFiltered(cmd *exec.Cmd, stdoutF, stderrF lineFilter) int {
-	stdout, err := cmd.StdoutPipe()
+func runFiltered(tc *toolCommand, stdoutF, stderrF lineFilter) int {
+	stdout, err := tc.StdoutPipe()
 	if err != nil {
 		fmt.Fprintln(os.Stderr, "vintner:", err)
 		return 1
 	}
-	stderr, err := cmd.StderrPipe()
+	stderr, err := tc.StderrPipe()
 	if err != nil {
 		fmt.Fprintln(os.Stderr, "vintner:", err)
 		return 1
 	}

-	if err := cmd.Start(); err != nil {
+	if err := tc.Start(); err != nil {
 		fmt.Fprintln(os.Stderr, "vintner:", err)
 		return 1
 	}
+	stopSignals := forwardSignals(tc.Process)
+	defer stopSignals()

 	doneOut := make(chan struct{})
 	doneErr := make(chan struct{})
 	go func() { pumpLines(stdout, os.Stdout, stdoutF); close(doneOut) }()
 	go func() { pumpLines(stderr, os.Stderr, stderrF); close(doneErr) }()

-	err = cmd.Wait()
+	err = tc.Wait()
 	drain(doneOut)
 	drain(doneErr)

 	if err != nil {
+		if tc.timedOut() {
+			fmt.Fprintln(os.Stderr, tc.timeoutMessage())
+			return 124
+		}
 		if exitErr, ok := err.(*exec.ExitError); ok {
 			return exitErr.ExitCode()
 		}
@@ -310,4 +347,11 @@ func pumpLines(r io.Reader, w *os.File, filter lineFilter) {
 		}
 		fmt.Fprintln(w, line)
 	}
+	// bufio.Scanner silently stops (dropping the rest of the stream) once a
+	// single line exceeds its 16MB buffer - surface that rather than letting
+	// build output vanish without explanation (heavily templated C++ error
+	// messages are the realistic way to hit this).
+	if err := scanner.Err(); err != nil {
+		fmt.Fprintf(w, "vintner: output truncated: %v\n", err)
+	}
 }
@@ -0,0 +1,68 @@
+package wrapper
+
+import (
+	"os"
+	"os/exec"
+	"os/signal"
+	"syscall"
+	"time"
+)
+
+// killGrace bounds how long a forwarded SIGINT/SIGTERM gets to make a
+// subprocess tree exit on its own before escalating to SIGKILL - long
+// enough for wineserver to tear down a Windows process tree cleanly, short
+// enough that an unresponsive one doesn't hang vintner's own shutdown.
+const killGrace = 5 * time.Second
+
+// setNewProcessGroup puts cmd's eventual child in its own process group
+// (pgid = its own pid) instead of inheriting vintner's. Without this, a
+// caller that signals vintner by PID alone (a CI runner enforcing a
+// timeout, a supervisor's `kill <pid>`) never reaches the wine/wineserver
+// tree underneath it, which is then reparented to init and keeps running -
+// wasting CPU, holding file locks, leaving stray FIFOs/temp files behind.
+// (Interactive Ctrl-C already reaches every process in the terminal's
+// foreground group regardless of this, but forwardSignals below handles
+// that case too now that the child has moved to its own group.)
+func setNewProcessGroup(cmd *exec.Cmd) {
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+}
+
+// forwardSignals relays SIGINT/SIGTERM received by vintner itself to
+// proc's entire process group (proc must have been started via a cmd that
+// called setNewProcessGroup, making proc.Pid also the group id), escalating
+// to SIGKILL after killGrace if the group hasn't exited by then. Callers
+// must call the returned stop func once the process has actually exited
+// (e.g. right after cmd.Wait() returns), both to stop listening for
+// signals and to cancel a pending escalation.
+func forwardSignals(proc *os.Process) (stop func()) {
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
+	done := make(chan struct{})
+
+	go func() {
+		pgid := -proc.Pid
+		for {
+			select {
+			case sig := <-sigCh:
+				s, ok := sig.(syscall.Signal)
+				if !ok {
+					continue
+				}
+				_ = syscall.Kill(pgid, s)
+				select {
+				case <-time.After(killGrace):
+					_ = syscall.Kill(pgid, syscall.SIGKILL)
+				case <-done:
+					return
+				}
+			case <-done:
+				return
+			}
+		}
+	}()
+
+	return func() {
+		signal.Stop(sigCh)
+		close(done)
+	}
+}
@@ -0,0 +1,43 @@
+package wrapper
+
+import (
+	"os"
+	"os/exec"
+	"syscall"
+	"testing"
+	"time"
+)
+
+// TestForwardSignalsKillsChild verifies the actual mechanism that keeps a
+// wine subprocess from being orphaned: a SIGTERM delivered to the current
+// process (mimicking `kill <vintner-pid>`, not an interactive Ctrl-C) must
+// reach a child started with setNewProcessGroup, even though it's no longer
+// in the same process group.
+func TestForwardSignalsKillsChild(t *testing.T) {
+	cmd := exec.Command("sleep", "30")
+	setNewProcessGroup(cmd)
+	if err := cmd.Start(); err != nil {
+		t.Fatalf("starting sleep: %v", err)
+	}
+	stop := forwardSignals(cmd.Process)
+	defer stop()
+
+	// signal.Notify (inside forwardSignals) intercepts this rather than
+	// letting it terminate the test binary itself.
+	if err := syscall.Kill(os.Getpid(), syscall.SIGTERM); err != nil {
+		t.Fatalf("signaling self: %v", err)
+	}
+
+	done := make(chan error, 1)
+	go func() { done <- cmd.Wait() }()
+
+	select {
+	case err := <-done:
+		if err == nil {
+			t.Fatal("expected the child to be killed by the forwarded signal, but it exited successfully")
+		}
+	case <-time.After(3 * time.Second):
+		cmd.Process.Kill()
+		t.Fatal("child was still running 3s after the signal should have been forwarded")
+	}
+}
@@ -0,0 +1,97 @@
+package wrapper
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"syscall"
+	"time"
+)
+
+// waitDelay bounds how long cmd.Wait() itself may block after the process
+// group has already been told to die (by a timeout or a forwarded signal) -
+// usually resolved immediately, but a wedged Wine transport is exactly the
+// case that isn't guaranteed to notice a plain SIGKILL right away.
+const waitDelay = 5 * time.Second
+
+// commandTimeout returns how long a single tool invocation may run before
+// vintner kills it and reports a timeout, from VINTNER_TIMEOUT (a
+// time.ParseDuration string, e.g. "30m", "2h"). Unset, empty, or invalid
+// all mean "no timeout" (0) - the default stays a plain, unbounded build,
+// matching every real build observed so far (Ogre3D's from-scratch build
+// alone ran several minutes). This exists for exactly one failure mode: a
+// wedged Wine-hosted process (a corrupted MSBuild node-reuse worker in the
+// one confirmed case so far, but nothing about the mechanism is
+// MSBuild-specific) that will otherwise never exit on its own, hanging
+// vintner - and whatever's waiting on vintner - forever with no feedback.
+// Automated/scripted callers that would rather fail loudly after N minutes
+// than risk hanging indefinitely can set this; interactive use is
+// unaffected unless it's set.
+func commandTimeout() time.Duration {
+	v := os.Getenv("VINTNER_TIMEOUT")
+	if v == "" {
+		return 0
+	}
+	d, err := time.ParseDuration(v)
+	if err != nil || d <= 0 {
+		return 0
+	}
+	return d
+}
+
+// toolCommand wraps the exec.Cmd every wine-hosted tool invocation is built
+// from, plus enough state to tell a VINTNER_TIMEOUT kill apart from every
+// other failure once Wait() returns.
+type toolCommand struct {
+	*exec.Cmd
+	ctx     context.Context
+	cancel  context.CancelFunc
+	timeout time.Duration // 0 if VINTNER_TIMEOUT wasn't set
+}
+
+// newToolCommand builds a toolCommand: its own process group
+// (setNewProcessGroup) and, when VINTNER_TIMEOUT is set, a deadline that
+// kills the *whole group* - not just the immediate `wine` process, since a
+// wedged Wine-hosted child surviving past its parent is exactly the
+// scenario this needs to reach - if the tool hasn't finished in time.
+//
+// Callers must defer the returned cleanup func, and should call
+// timedOut() after Wait() returns to tell a timeout-triggered kill apart
+// from every other failure.
+func newToolCommand(name string, args ...string) (tc *toolCommand, cleanup func()) {
+	timeout := commandTimeout()
+	if timeout <= 0 {
+		cmd := exec.Command(name, args...)
+		setNewProcessGroup(cmd)
+		return &toolCommand{Cmd: cmd, ctx: context.Background()}, func() {}
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	cmd := exec.CommandContext(ctx, name, args...)
+	setNewProcessGroup(cmd)
+	// cmd.Cancel's default (Go 1.20+) only signals the immediate child;
+	// override it to reach the whole process group, same as
+	// forwardSignals - the wedged process a timeout exists to clean up is
+	// typically under wine, not wine itself.
+	cmd.Cancel = func() error {
+		if cmd.Process == nil {
+			return nil
+		}
+		return syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+	}
+	cmd.WaitDelay = waitDelay
+	tc = &toolCommand{Cmd: cmd, ctx: ctx, cancel: cancel, timeout: timeout}
+	return tc, cancel
+}
+
+// timedOut reports whether this command was killed by its own
+// VINTNER_TIMEOUT deadline rather than exiting (however it exited) on its
+// own - call after Wait() returns a non-nil error.
+func (tc *toolCommand) timedOut() bool {
+	return tc.ctx.Err() == context.DeadlineExceeded
+}
+
+func (tc *toolCommand) timeoutMessage() string {
+	return fmt.Sprintf("vintner: %s: timed out after %s (VINTNER_TIMEOUT), killed", tc.Path, tc.timeout)
+}
@@ -0,0 +1,82 @@
+package wrapper
+
+import (
+	"syscall"
+	"testing"
+	"time"
+)
+
+func TestCommandTimeout(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		env  string
+		want time.Duration
+	}{
+		{"unset", "", 0},
+		{"valid", "30m", 30 * time.Minute},
+		{"invalid unit-less number", "30", 0},
+		{"zero", "0s", 0},
+		{"negative", "-5m", 0},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Setenv("VINTNER_TIMEOUT", tc.env)
+			if got := commandTimeout(); got != tc.want {
+				t.Errorf("commandTimeout() with VINTNER_TIMEOUT=%q = %v, want %v", tc.env, got, tc.want)
+			}
+		})
+	}
+}
+
+// TestNewToolCommandKillsOnTimeout is the real end-to-end check: start a
+// process that would otherwise run far longer than the timeout (mimicking
+// a wedged Wine-hosted tool), and confirm newToolCommand's deadline
+// actually kills it - not just that timedOut() would report true in
+// principle, but that Wait() actually returns, promptly, with the process
+// gone.
+func TestNewToolCommandKillsOnTimeout(t *testing.T) {
+	t.Setenv("VINTNER_TIMEOUT", "300ms")
+
+	tc, cleanup := newToolCommand("sleep", "30")
+	defer cleanup()
+
+	if err := tc.Start(); err != nil {
+		t.Fatalf("starting sleep: %v", err)
+	}
+	pid := tc.Process.Pid
+
+	done := make(chan error, 1)
+	go func() { done <- tc.Wait() }()
+
+	select {
+	case err := <-done:
+		if err == nil {
+			t.Fatal("expected sleep 30 to be killed by the timeout, but it exited successfully")
+		}
+		if !tc.timedOut() {
+			t.Errorf("Wait() returned an error (%v) but timedOut() = false", err)
+		}
+	case <-time.After(5 * time.Second):
+		t.Fatal("newToolCommand's timeout did not kill the process within 5s of a 300ms deadline")
+	}
+
+	// Belt-and-suspenders: the process should genuinely be gone, not just
+	// reported as such. Signal 0 sends nothing but still fails with ESRCH
+	// once the pid is gone - the standard Unix way to probe existence.
+	if err := syscall.Kill(pid, 0); err == nil {
+		t.Errorf("pid %d still exists after the timeout killed it", pid)
+	}
+}
+
+func TestNewToolCommandNoTimeoutByDefault(t *testing.T) {
+	t.Setenv("VINTNER_TIMEOUT", "")
+
+	tc, cleanup := newToolCommand("true")
+	defer cleanup()
+
+	if err := tc.Run(); err != nil {
+		t.Fatalf("running `true` with no VINTNER_TIMEOUT set: %v", err)
+	}
+	if tc.timedOut() {
+		t.Error("timedOut() = true for a command that finished well within any reasonable time, with no timeout configured")
+	}
+}
@@ -4,7 +4,11 @@
 // filtering its output.
 package wrapper

-import "github.com/Cheviiot/vintner/internal/wineenv"
+import (
+	"sort"
+
+	"github.com/Cheviiot/vintner/internal/wineenv"
+)

 // dirKind selects which install directory a tool's real .exe lives in.
 type dirKind int
@@ -46,6 +50,32 @@ var Tools = map[string]spec{
 // nativeTools are handled entirely without Wine.
 var nativeTools = map[string]bool{"cmd": true, "findstr": true}

+// IsTool reports whether name is a recognized wrapped tool - either a
+// Wine-hosted one in Tools or a native shim in nativeTools. Shared between
+// the ordinary multi-call dispatch (invoked *as* one of these names via a
+// same-directory symlink) and `vintner <tool> ...` direct dispatch, so both
+// recognize exactly the same set of names.
+func IsTool(name string) bool {
+	_, ok := Tools[name]
+	return ok || nativeTools[name]
+}
+
+// ToolNames returns every recognized tool name, sorted - Tools and
+// nativeTools combined. Used to generate shell completion without a
+// separate hand-maintained list that could drift from the real set (as
+// happened once already with a stale --with-dxsdk completion entry).
+func ToolNames() []string {
+	names := make([]string, 0, len(Tools)+len(nativeTools))
+	for name := range Tools {
+		names = append(names, name)
+	}
+	for name := range nativeTools {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+	return names
+}
+
 func (s spec) exeDir(p *wineenv.Paths) string {
 	switch s.dir {
 	case dirSDK:
@@ -0,0 +1,63 @@
+package wrapper
+
+import (
+	"testing"
+
+	"github.com/Cheviiot/vintner/internal/wineenv"
+)
+
+func TestSpecExeDir(t *testing.T) {
+	paths := &wineenv.Paths{
+		BinDir:        "/bin-dir",
+		SDKBinDir:     "/sdk-bin-dir",
+		MSBuildBinDir: "/msbuild-bin-dir",
+	}
+	for _, tc := range []struct {
+		name string
+		dir  dirKind
+		want string
+	}{
+		{"dirBin", dirBin, "/bin-dir"},
+		{"dirSDK", dirSDK, "/sdk-bin-dir"},
+		{"dirMSBuild", dirMSBuild, "/msbuild-bin-dir"},
+	} {
+		s := spec{dir: tc.dir}
+		if got := s.exeDir(paths); got != tc.want {
+			t.Errorf("%s: exeDir() = %q, want %q", tc.name, got, tc.want)
+		}
+	}
+}
+
+func TestToolsAndNativeToolsAreDisjoint(t *testing.T) {
+	for name := range Tools {
+		if nativeTools[name] {
+			t.Errorf("%q is in both Tools and nativeTools", name)
+		}
+	}
+}
+
+func TestEveryToolHasAnExeName(t *testing.T) {
+	for name, s := range Tools {
+		if s.exeName == "" {
+			t.Errorf("Tools[%q] has no exeName", name)
+		}
+	}
+}
+
+func TestIsTool(t *testing.T) {
+	for name := range Tools {
+		if !IsTool(name) {
+			t.Errorf("IsTool(%q) = false, want true (it's in Tools)", name)
+		}
+	}
+	for name := range nativeTools {
+		if !IsTool(name) {
+			t.Errorf("IsTool(%q) = false, want true (it's in nativeTools)", name)
+		}
+	}
+	for _, name := range []string{"download", "install", "env", "version", "help", "completion", "frobnicate", ""} {
+		if IsTool(name) {
+			t.Errorf("IsTool(%q) = true, want false", name)
+		}
+	}
+}
Author	SHA1	Message	Date
Cheviiot	de49e80cb7	Resume interrupted downloads instead of restarting from scratch MSVC/WinSDK/WDK/DXSDK payloads run into the hundreds of MB to several GB, so a dropped connection or a retry after a transient error used to mean throwing away everything already fetched and starting over from byte 0. Track progress in a dest+".part" file and resume it via an HTTP Range request, falling back to a full restart when the server doesn't honor Range (200 instead of 206) or the local part is stale (416).	2026-07-25 18:17:59 +10:00
Cheviiot	98bac75767	Make the wine-not-found error actionable FindWine's error used to just say wine64/wine weren't on PATH, with no next step - surface the exact install fix ("install the wine package") instead of leaving the reader to figure that out themselves.	2026-07-25 18:17:59 +10:00
Cheviiot	5cf52c9f9f	Add `vintner doctor` for diagnosing a broken wine/toolchain setup A misconfigured environment (wine missing, msitools not installed, a partially-built toolchain) otherwise only surfaces as a wine-specific error buried deep inside a build. `vintner doctor` checks wine itself (found and actually runs), the optional extraction tools download needs, and every installed <dest>/bin/<arch> toolchain's on-disk layout, printing a pass/fail checklist and exiting non-zero if anything's broken.	2026-07-25 18:14:47 +10:00
Cheviiot	b366dfa9ac	Add a concurrency lock for download/install against the same destination combineDirTrees' merge logic assumes it's the only thing moving files into a given target at a time; two `vintner download`/`install` runs racing against the same --dest could otherwise interleave os.Rename calls and corrupt the tree instead of erroring cleanly. Take an exclusive, non-blocking flock(2) on the destination for the duration of each run, so a second invocation fails immediately with a clear message instead of silently colliding with the first.	2026-07-25 18:10:56 +10:00
Cheviiot	738234186d	Run wrapped tools directly as `vintner <tool> ...`, no PATH needed `vintner cl ...`, `vintner msbuild ...`, etc. now work without adding <dest>/bin/<arch> to PATH or relying on the same-directory symlinks `install` sets up there. wrapper.Run gained an explicit binDir parameter (empty string preserves the existing os.Executable()-based self-location for the ordinary multi-call/symlink case) so cmd/vintner's new runTool can point it at a resolved toolchain directory instead. Resolution order: VINTNER_BIN if set (same meaning as `env --bin` - point it at a <dest>/bin/<arch> directory directly, for a non-default --dest or a specific architecture), else <defaultToolchainDir>/bin/ <hostArch> - the layout a plain `vintner download && vintner install` with no --dest override produces. A missing toolchain gets a clear error pointing at both fixes, rather than bubbling up whatever wineenv.Load's env.json error looks like. Also fixed shell completion falling out of sync with the actual tool list: the bash/zsh scripts previously hand-copied tool/flag names (and had already gone stale once - --with-dxsdk was missing from the download flag completions since it was added). The tool name list is now generated from wrapper.ToolNames() instead of hand-maintained, and both scripts now complete tool names too, so `vintner <TAB>` suggests `cl`, `link`, `msbuild`, etc. alongside the management subcommands. Verified end-to-end with a minimal PATH (/usr/bin:/bin only, no toolchain dir on it at all): `vintner cl /nologo hello.c` compiled successfully, and `vintner msbuild -t:Rebuild ...` rebuilt the same real KMDF driver verified earlier this session - both via the default ~/.vintner/bin/<hostArch> resolution, no VINTNER_BIN override needed.	2026-07-25 16:23:46 +10:00
Cheviiot	f6b9a0811a	Prevent and recover from wedged Wine-hosted processes Prompted by a real incident: an MSBuild node-reuse worker (its own /nodeReuse:true default) survived a build getting interrupted, came back deadlocked, and got reused by the next `msbuild` invocation - which then failed with a confusing, unrelated-looking `System.TypeLoadException` on Microsoft.VisualStudio.Telemetry on every call for hours, until the stale process was killed by hand. That's exactly the "unrelated blocker" noted in this repo's own earlier session notes (CLAUDE.md) while debugging a real project's build - it wasn't a missing dependency, it was a corrupted reused process. Two changes: - vintner now forces /nodeReuse:false on every msbuild invocation (unless the caller already passed their own /nodeReuse or /nr switch), so a wedged worker can never poison a later, unrelated build in the first place. Costs each invocation the couple-hundred- ms/node startup time node reuse exists to save. - VINTNER_TIMEOUT (a duration string, e.g. "30m") bounds how long any single tool invocation is allowed to run, for the case something wedges that isn't MSBuild-specific. Every exec.Command site in internal/wrapper now goes through a shared newToolCommand constructor that, when the timeout is set, kills the whole process group (not just the immediate `wine` process - a wedged child surviving under it is exactly the scenario this needs to reach) via a context deadline, and reports a clear "timed out after Xm" message (exit 124, matching the timeout(1) convention) instead of a bare "signal: killed". Unset by default - every real build observed stays unbounded, matching Windows' own behavior. Verified end-to-end, not just at the unit level: a real `sleep 30` through the `cmd` native wrapper with VINTNER_TIMEOUT=1s was killed within the deadline and reported the timeout clearly (exit 124); a real `cl` invocation with the same 1s timeout finished normally (0.26s) without being mistaken for a hang.	2026-07-25 15:58:22 +10:00
Cheviiot	bdea270d71	docs: list cabextract as a prerequisite for --with-dxsdk	2026-07-25 15:44:36 +10:00
Cheviiot	25f751e874	Build old (pre-v145) PlatformToolset-pinned .vcxproj files vintner only ever downloads one compiler generation, but real-world .vcxproj files are pinned to whichever PlatformToolset they were last saved under - v142 (VS2019) for anything not actively maintained is extremely common. MSBuild checks toolset "installed-ness" (MSB8020) by testing whether MSBuild/Microsoft/VC/v<schema>/Platforms/<arch>/ PlatformToolsets/<toolset>/ exists on disk - a plain file lookup our downloaded MSBuild package only satisfies for the exact generation it shipped. `install` now symlinks every historical numeric PlatformToolset name (v90 through v143) onto whichever real toolset directory is actually present, so any of them resolves transparently; Toolset.props/ .targets don't hardcode a version number, so aliasing is correct, not just a workaround. Three more MSBuild property/environment issues came with it, all found building a real years-old project against the one modern toolchain vintner installs: - VCInstallDir_<N>/VCToolsInstallDir_<N> needed a third numbering source (PlatformToolset short names from Microsoft.VCToolsVersion. v<N>.default.props) alongside the existing MSBuild schema-version and known-toolset lists, so the env-var-driven half of toolset resolution covers the same names the on-disk alias does. - VCToolsVersion must be a real version string: left unset, it falls back to a literal placeholder that then hits an unconditional version-string comparison elsewhere in Microsoft.CppBuild.targets (MSB4184). Setting it to the real installed version in turn requires CheckMSVCComponents=false, since CheckVCToolsetVersion (MSB8052) otherwise rejects an aliased PlatformToolset whenever its numeric generation doesn't match VCToolsVersion's - exactly the case aliasing creates on purpose. Everything else CheckMSVCComponents gates is diagnostic-only (MFC/ATL/Spectre presence warnings), so disabling it costs nothing else. - WindowsTargetPlatformVersion needed to become an explicit /p: global property on the msbuild command line, not just an env var: legacy .vcxproj files commonly hardcode this in a PropertyGroup, and an explicit project assignment always wins over an inherited environment variable of the same name. A command-line global property is the one thing a project file can't override. Only injected when the caller hasn't already pinned it themselves.	2026-07-25 15:41:09 +10:00
Cheviiot	4795c7c105	Add DirectX SDK (D3DX9) download support download --with-dxsdk fetches the DirectX SDK (June 2010) - the last standalone release of D3DX9/10/11, XInput and XAudio2, dropped from the Windows SDK entirely once D3DX was deprecated, but still needed by plenty of legacy code. Like the WDK, it isn't part of the VS installer manifest, so this is its own self-contained fetch+unpack path: the installer is a self-extracting CAB, unpacked directly via cabextract (already a prerequisite for the WinSDK .msi payloads) with its -F filter restricting extraction to just Include/ and Lib/ - about 21MB out of the installer's 1.2GB uncompressed payload. Verified against the real installer: real d3dx9.h and d3dx9.lib (x86 and x64) extracted correctly and linked into an actual legacy game client build.	2026-07-25 15:40:41 +10:00
Cheviiot	91471397fa	Fix toolrelay.exe's mt.exe detection: it never matched a real path IsMtExe() looked for the last '\\' in the target executable path to find the bare filename, but vintner passes toolExePath straight from Go's filepath.Join (forward slashes) all the way through to CreateProcessW - so the path toolrelay.exe actually receives has no backslash in it at all, and IsMtExe() compared the entire path against "mt.exe", which of course never matched. The whole point of this file - translating mt.exe's CMake-compatibility exit code (0x41020001 -> 0xbb) before Wine's own exit-code truncation destroys it - has silently never fired in real usage. This had gone unnoticed because MSBuild's rawStdout path bypasses toolrelay.exe entirely, and every real end-to-end test so far (msbuild-driven builds, including the KMDF driver) went through that path. Found while getting a CMake+Ninja-generated MSVC build of a real project (Ogre3D) past its `cmake -E vs_link_exe` manifest step, which depends on exactly this translation. Now checks for both '\\' and '/' and uses whichever separator occurs last in the path. Verified directly: `mt /manifest ... /notify_update` through the wrapper now exits 187 (0xbb) instead of 1, and the Ogre build gets past the manifest-embedding step it was failing at.	2026-07-25 11:55:05 +10:00
Cheviiot	94a19e6b43	Show git commit and build time in `vintner version` Uses Go's automatic VCS build-info stamping (vcs.revision/vcs.time/ vcs.modified, embedded by `go build` since Go 1.18 - no -ldflags changes needed, works the same for a CI release build and a plain local `go build`). Knowing the exact commit a bug report's binary was built from, not just the X.Y.Z tag, is the point - two builds of the same tag could still differ. Split the pure formatting logic (formatVersion) from the debug.ReadBuildInfo() call so it's actually unit-testable: `go test` binaries don't get VCS stamping the way `go build` ones do, so there was no way to exercise the revision-formatting branch through versionString() itself.	2026-07-25 11:37:02 +10:00
Cheviiot	6186837fd2	docs: note that Nivora installs get shell completion automatically	2026-07-25 11:33:41 +10:00
Cheviiot	c049274626	Rewrite README prose: cut repeated self-assurance, tighten sentences The old version restated "independently implemented"/"original to this project" in three separate places, which reads as protesting too much rather than as confidence. Credits the msvc-wine inspiration once, plainly, and drops the rest. Also split several overlong comma-chained sentences, fixed the WDK section (a sentence was cut in half by its own code block), and cleaned up the license paragraph's phrasing. Content is unchanged - verified the two claims most worth double-checking (the clang-cl/lld-link path, and that `stplr install nivora/vintner` actually resolves) rather than just rewording them.	2026-07-25 10:55:01 +10:00
Cheviiot	fc20b2fb15	Add test coverage for cmd/vintner and internal/i18n Both were at 0% coverage. Focused on what's safely testable without touching the network or filesystem: flag validation (--architecture/ --host-arch, the same guard added in the stability pass), subcommand dispatch and aliases, help/usage error paths, and - for i18n - full language-detection table coverage plus a completeness check that every catalog key has both an EN and RU entry (an English-only or Russian-only entry would silently degrade rather than fail loudly, so this is worth locking in). cmd/vintner: 0% -> 28.8%, i18n: 0% -> 94.1%.	2026-07-25 10:41:48 +10:00
Cheviiot	26f6df6a9a	Add bash/zsh shell completion vintner completion bash\|zsh prints a completion script meant to be sourced (source <(vintner completion bash)); completes subcommands (including short aliases), download's flags, and directory arguments for install/env --bin. Mentioned in the top-level usage text and documented in the README. The Nivora package doesn't auto-install these system-wide yet - it'd need Stapler's install-completion helper, whose calling convention isn't documented anywhere in this repo or Nivora's other packages, so guessing at it risked a broken package build for a nice-to-have. source <(vintner completion bash) works today regardless of install method (Nivora, prebuilt binary, or from source).	2026-07-25 10:39:22 +10:00
Cheviiot	98ee39018a	Stop orphaning wine subprocesses when vintner is killed by PID Every wrapped tool invocation (cl/link/msbuild/etc via wine, plus the native cmd/findstr shims) now starts its child in its own process group and forwards SIGINT/SIGTERM to that group, escalating to SIGKILL after a 5s grace period if it doesn't exit. Previously, interactive Ctrl-C happened to work by accident (the child inherited the terminal's foreground process group and got the signal directly), but anything that signals vintner by PID alone - a CI job's timeout, a supervisor's `kill <pid>` - never reached the wine/wineserver tree underneath it, which got reparented to init and kept running: wasted CPU, held file locks, stray FIFOs/temp files. Verified two ways: a unit test (signals_test.go) that starts a detached `sleep 30`, signals the test process itself, and checks the child actually dies; and a real end-to-end run - killed an in-flight `msbuild` driver build by PID mid-compile and confirmed no orphaned msbuild/cl/link/vintner process was left behind (wineserver and its persistent service processes are expected to survive, by design - see pipeDrainGrace's doc comment).	2026-07-25 10:34:45 +10:00
Cheviiot	4b3aacfdf7	fix(ci): let staticcheck install its own newer Go instead of reusing 1.23	2026-07-25 04:21:15 +10:00
Cheviiot	0b7b686e3a	Add staticcheck to CI Caught a real dead-code finding (an unused off() helper) during this session's stability pass; running it on every push/PR catches this class of issue automatically instead of relying on someone happening to run it locally.	2026-07-25 04:19:34 +10:00
Cheviiot	0a4f05c673	Add regression test for deterministic dependency resolution order Loops ExpandSelection 50 times and checks the result order never changes, guarding against the map-iteration-order bug fixed in the previous commit ever coming back unnoticed. Verified this actually catches the regression by temporarily reverting the fix locally.	2026-07-25 04:17:57 +10:00
Cheviiot	e0475101b2	Rewrite README with real install paths, TOC, and current command surface Adds the two installation options that now actually exist (Nivora package, prebuilt GitHub Release binary) alongside building from source, a table of contents, CI/release/license badges, and a Language section for VINTNER_LANG. Moves the more implementation- focused toolrelay.exe/compatibility-patches explanations into collapsible sections so the top of the page stays focused on using the tool rather than how it's built.	2026-07-25 04:16:33 +10:00
Cheviiot	d11b534fa1	Stability pass: deterministic dependency order, retry backoff, input validation Found via manual audit plus a staticcheck run: - collectDependencyClosure iterated a package's dependencies map directly, so which package "won" a same-key collision (and the order things got downloaded/unpacked in) could vary between runs of the exact same download command. Sort the dependency targets first, matching what --print-deps-tree's tree-printer already did. Verified two consecutive --print-deps-tree runs now produce byte-identical output. - HTTP retry loops (manifest fetch, payload download) retried immediately with no backoff, which just hammers a server harder during exactly the kind of transient failure retries exist for. Added a capped exponential backoff (1s/2s/4s/8s/10s). - --architecture/--host-arch accepted any string silently; a typo'd value matched nothing during package selection and surfaced as a confusing downstream failure far from the actual mistake. Now rejected up front with a clear error. - pumpLines' bufio.Scanner silently stops (dropping the rest of a tool's output) if a single line ever exceeds its buffer - narrow but real for pathological cases like heavily templated C++ diagnostics. Now at least reports that truncation happened instead of losing output with no trace. - Removed select.go's unused off() helper (staticcheck U1000). Re-verified end-to-end after these changes: a real KMDF driver build and a plain cl/link build both still succeed.	2026-07-25 04:14:34 +10:00