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.

.github/workflows/ci.yml

@@ -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

README.md

@@ -1,37 +1,92 @@
 # vintner
 
-Cross compile with MSVC on Linux, using Wine — a single-binary Go tool
+[![CI](https://github.com/Cheviiot/vintner/actions/workflows/ci.yml/badge.svg)](https://github.com/Cheviiot/vintner/actions/workflows/ci.yml)
-inspired by [mstorsjo/msvc-wine](https://github.com/mstorsjo/msvc-wine)'s
+[![Release](https://img.shields.io/github/v/release/Cheviiot/vintner)](https://github.com/Cheviiot/vintner/releases/latest)
-approach (download the real MSVC/WinSDK, wrap the compiler under Wine),
+[![License: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE.txt)
-implemented independently.
 
-Once installed, you invoke the real Microsoft toolchain exactly like on
+vintner cross-compiles with the real MSVC toolchain on Linux, using Wine.
-Windows: `cl`, `link`, `lib`, `rc`, `midl`, `mc`, `mt`, `dumpbin`, `msbuild`,
+One Go binary drops in as `cl`, `link`, `lib`, `rc`, `midl`, `mc`, `mt`,
-`nmake`, `ml`, `ml64`, `armasm`, `armasm64`, plus trivial `cmd`/`findstr`
+`dumpbin`, `msbuild`, `nmake`, `ml`, `ml64`, `armasm`, `armasm64`, plus
-shims, all just work from your `PATH`.
+`cmd`/`findstr` shims, so once installed you invoke the real Microsoft
+tools exactly like on Windows. It handles full MSBuild projects, and with
+`--with-wdk`, real KMDF/UMDF Windows drivers.
+
+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)
+- [Building drivers (WDK)](#building-drivers-wdk)
+- [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
+vintner is a multi-call binary, like busybox: it behaves differently
-it's invoked as (a "multi-call binary", like busybox):
+depending on the name it's invoked as.
 
-- Invoked as `cl`, `link`, `lib`, ... → it loads a small per-architecture
+- As `cl`, `link`, `lib`, and the rest: it loads a per-architecture
-  `env.json`, builds the `INCLUDE`/`LIB`/`WINEPATH` environment Wine needs,
+  `env.json`, sets `INCLUDE`/`LIB`/`WINEPATH`, and rewrites absolute Unix
-  rewrites absolute unix paths in the arguments into Wine's `z:\...` form
+  paths in the arguments to Wine's `z:\...` form (Wine and cl.exe
-  (working around [a Wine/cl.exe include-path bug](https://bugs.winehq.org/show_bug.cgi?id=55200)),
+  otherwise mishandle relative includes — see
-  runs the real `.exe` under `wine`/`wine64`, and rewrites the tool's output
+  [winehq bug 55200](https://bugs.winehq.org/show_bug.cgi?id=55200)). It
-  back from `z:\...` paths to plain unix paths so your build system's error
+  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
+- As `vintner`: it exposes the `download`, `install`, `env`, `version`
-  `version` management subcommands described below (each also has a short
+  and `completion` subcommands below (short aliases: `dl`, `i`, `e`, `v`;
-  alias: `dl`, `i`, `e`, `v`; `help`/`h` prints usage).
+  `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)).
+
+On ALT Linux:
+
+```bash
+pkcon install wine msitools git
+```
 
 ## Quick start
 
 ```bash
-# 1. Download and unpack MSVC + Windows SDK into ~/.vintner (requires
+# 1. Download and unpack MSVC + Windows SDK into ~/.vintner (accepts
-#    accepting Microsoft's Visual Studio Build Tools license, and msitools
+#    Microsoft's Visual Studio Build Tools license). Pass --dest <dir>
-#    for unpacking .msi payloads). Pass --dest <dir> for a different location.
+#    for a different location.
 vintner download --accept-license
 
 # 2. Wire up the tool wrappers
@@ -42,19 +97,6 @@ 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
-```
-
 ## Commands
 
 ```
@@ -63,48 +105,72 @@ vintner install (i) [dir]                                         wire up wrappe
 vintner env (e) --bin <dir>/bin/<arch>                            print INCLUDE/LIB for native clang-cl/lld-link use
 vintner version (v)                                               print the version
 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
+`--architecture` (repeatable: `x86`/`x64`/`arm`/`arm64`/`host`),
-Windows Driver Kit, for building KMDF/UMDF drivers), `--ignore`,
+`--host-arch`, `--only-host`, `--with-wdk` (see below), `--ignore`
-`--only-download`, `--only-unpack`, `--keep-unpack`, `--skip-patch`,
+(repeatable), `--only-download`, `--only-unpack`, `--keep-unpack`,
-`--cache`, `--language`, `--include-optional`, `--skip-recommended`,
+`--skip-patch`, `--cache`, `--language`, `--include-optional`,
-`--major`, `--preview`, `--manifest`, `--list-workloads`,
+`--skip-recommended`, `--major`, `--preview`, `--manifest`,
-`--list-components`, `--print-deps-tree`. Run `vintner download -h` for the
+`--list-workloads`, `--list-components`, `--print-deps-tree`. Run
-full list with descriptions.
+`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
+and its human-readable title from the fetched manifest, then exit
-without downloading anything - useful for discovering what to pass as a bare
+without downloading anything. Useful for finding what to pass as a bare
-package id or via `--with-*`. `--print-deps-tree` prints the dependency tree
+package id or through `--with-*`. `--print-deps-tree` prints the
-of whatever would actually be selected (honoring every other flag), also
+dependency tree of whatever would actually be selected — honoring every
-without downloading.
+other flag — without downloading anything.
 
-### Building drivers (WDK)
+## Building drivers (WDK)
 
-`vintner download --with-wdk` additionally fetches the Windows Driver Kit
+`--with-wdk` also fetches the Windows Driver Kit: headers, import libs,
-(headers, import libs, and the MSBuild `WindowsKernelModeDriver10.0`/
+and the MSBuild `WindowsKernelModeDriver10.0`/`WindowsUserModeDriver10.0`
-`WindowsUserModeDriver10.0` PlatformToolsets) so `msbuild` can build real
+PlatformToolsets.
-KMDF/UMDF drivers - compiling, linking, INF stamping and the `Inf2Cat`
+
-signability check (with `SignMode=off`) all work under Wine. Verified
+```bash
-end-to-end against a real sample driver from
+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
+## Language
 
-CLI messages (usage text, progress lines, prompts) are in English by
+CLI text (usage, progress lines, prompts) defaults to English. Set
-default. Set `VINTNER_LANG=ru` (or have a `ru`-prefixed `LC_ALL`/
+`VINTNER_LANG=ru` (or a `ru`-prefixed `LC_ALL`/`LC_MESSAGES`/`LANG`, e.g.
-`LC_MESSAGES`/`LANG`, e.g. `ru_RU.UTF-8`) for Russian. Deeper error text
+`ru_RU.UTF-8`) for Russian:
-bubbled up from internal packages stays in English.
 
-### Using clang-cl/lld-link instead of Wine
+```bash
+VINTNER_LANG=ru vintner help
+```
 
-You don't need Wine at all if you drive the (nonredistributable) MSVC/WinSDK
+Error text from internal packages stays in English regardless.
-headers and libraries with Clang/LLD in MSVC-compatible mode:
+
+## 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 +178,44 @@ 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
+Go 1.23+ builds it. `wine`/`msitools` are only needed at run time, for
-run time (`install`/tool invocation and `download` respectively).
+`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.
 
 ## License
 
-MIT, see [LICENSE.txt](LICENSE.txt) - covers vintner's own source only. The
+MIT (see [LICENSE.txt](LICENSE.txt)) for vintner's own source. The MSVC
-MSVC Build Tools / Windows SDK / WDK that `download` fetches remain governed
+Build Tools, Windows SDK, and WDK that `download` fetches stay under
-by Microsoft's own license (accepted via `--accept-license`), same as with
+Microsoft's own license (accepted via `--accept-license`), same as with
 any other way of obtaining them.

assets/vendor/toolrelay.cpp

@@ -79,8 +79,16 @@ HANDLE MakeKillOnCloseJob() {
 }
 
 bool IsMtExe(const wchar_t *path) {
-  const wchar_t *name = wcsrchr(path, L'\\');
+  // vintner passes toolExePath straight through from Go's filepath.Join,
-  name = name ? name + 1 : path;
+  // 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;
 }
 

cmd/vintner/completion.go

@@ -0,0 +1,140 @@
+package main
+
+import "fmt"
+
+// 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.
+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 --architecture --ignore -h --help"
+
+var bashCompletionScript = `# 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=($(compgen -W "download dl install i env e version v help h completion" -- "$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" -- "$cur"))
+            ;;
+    esac
+    return 0
+}
+complete -F _vintner_complete vintner
+`
+
+var zshCompletionScript = `#compdef vintner
+# vintner zsh completion - source <(vintner completion zsh)
+
+_vintner() {
+    local -a subcommands
+    subcommands=(
+        'download:fetch and unpack MSVC/WinSDK/WDK'
+        'dl:alias for download'
+        'install:wire up wrappers for a downloaded MSVC'
+        'i:alias for install'
+        'env:print INCLUDE/LIB for native clang-cl/lld-link use'
+        'e:alias for env'
+        'version:print the version'
+        'v:alias for version'
+        'help:print usage'
+        'h:alias for help'
+        'completion:print a shell completion script'
+    )
+
+    if (( CURRENT == 2 )); then
+        _describe 'command' subcommands
+        return
+    fi
+
+    case "${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]'
+                '--architecture[target architecture]:arch:(x86 x64 arm arm64 host)'
+                '--ignore[package id to skip]:package id:'
+                '-h[show help]'
+                '--help[show help]'
+            )
+            _arguments $flags
+            ;;
+        install|i)
+            _files -/
+            ;;
+        env|e)
+            _arguments \
+                '--bin[bin/<arch> directory produced by install]:directory:_files -/' \
+                '-h[show help]' '--help[show help]'
+            ;;
+        completion)
+            _values 'shell' bash zsh
+            ;;
+    esac
+}
+
+_vintner "$@"
+`

cmd/vintner/completion_test.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"os/exec"
+	"strings"
+	"testing"
+)
+
+// 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)
+			}
+		})
+	}
+}
+
+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)
+	}
+}

cmd/vintner/download.go

@@ -45,6 +45,17 @@ 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),
@@ -267,6 +278,9 @@ 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"

cmd/vintner/download_test.go

@@ -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)`)
+	}
+}

cmd/vintner/env_test.go

@@ -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)
+	}
+}

cmd/vintner/install_test.go

@@ -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)
+		}
+	}
+}

cmd/vintner/main.go

@@ -47,8 +47,10 @@ func runCLI(args []string) int {
 		return runInstall(args[1:])
 	case "env", "e":
 		return runEnv(args[1:])
+	case "completion":
+		return runCompletion(args[1:])
 	case "version", "v", "--version":
-		fmt.Println("vintner " + version)
+		fmt.Println(versionString())
 		return 0
 	case "-h", "--help", "help", "h":
 		printUsage()

cmd/vintner/main_test.go

@@ -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)
+			}
+		})
+	}
+}

cmd/vintner/paths_test.go

@@ -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)
+	}
+}

cmd/vintner/version.go

@@ -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)
+}

cmd/vintner/version_test.go

@@ -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)
+			}
+		})
+	}
+}

internal/download/extract_test.go

@@ -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)
+	}
+}

internal/download/fetch.go

@@ -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 != "" {

internal/download/fetch_test.go

@@ -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)
+		}
+	}
+}

internal/download/manifest.go

@@ -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

internal/download/manifest_test.go

@@ -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)
+		}
+	}
+}

internal/download/select.go

@@ -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

internal/download/select_test.go

@@ -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 {

internal/download/wdk_test.go

@@ -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)
+	}
+}

internal/i18n/i18n.go

@@ -74,6 +74,7 @@ Usage:
   vintner env (e) --bin <dir/bin/arch> print INCLUDE/LIB for native clang-cl/lld-link use
   vintner version (v)                  print the version
   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
@@ -81,6 +82,7 @@ has many, including --with-wdk, --list-workloads, --list-components and
 
 --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:
   cl, link, lib, ml, ml64, mc, midl, mt, rc, dumpbin, msbuild, nmake, armasm, armasm64, cmd, findstr
@@ -94,6 +96,7 @@ Once installed, add <dir>/bin/<arch> to PATH and invoke the tools directly:
   vintner env (e) --bin <dir/bin/arch> вывести INCLUDE/LIB для clang-cl/lld-link напрямую
   vintner version (v)                  показать версию
   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
@@ -101,6 +104,7 @@ Once installed, add <dir>/bin/<arch> to PATH and invoke the tools directly:
 
 --dest/[каталог] по умолчанию — ~/.vintner.
 Язык: установите VINTNER_LANG=en (или LANG=en_US...) для вывода на английском.
+Автодополнение: source <(vintner completion bash)  # или zsh
 
 После установки добавьте <dir>/bin/<arch> в PATH и вызывайте инструменты напрямую:
   cl, link, lib, ml, ml64, mc, midl, mt, rc, dumpbin, msbuild, nmake, armasm, armasm64, cmd, findstr

internal/i18n/i18n_test.go

@@ -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)
+	}
+}

internal/wrapper/clpost_test.go

@@ -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"})
+}

internal/wrapper/msbuildenv_test.go

@@ -0,0 +1,117 @@
+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["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)
+
+	for _, v := range []string{"v145", "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", "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 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"])
+	}
+}

internal/wrapper/native.go

@@ -29,7 +29,13 @@ func execInherit(args []string) int {
 	cmd.Stdin = os.Stdin
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
-	if err := cmd.Run(); err != nil {
+	setNewProcessGroup(cmd)
+	if err := cmd.Start(); err != nil {
+		return 127
+	}
+	stopSignals := forwardSignals(cmd.Process)
+	defer stopSignals()
+	if err := cmd.Wait(); err != nil {
 		if exitErr, ok := err.(*exec.ExitError); ok {
 			return exitErr.ExitCode()
 		}

internal/wrapper/run.go

@@ -91,6 +91,7 @@ func Run(tool string, args []string) int {
 		}
 		cmd.Env = env
 		cmd.Stdin = os.Stdin
+		setNewProcessGroup(cmd)
 		exitCode = runRawStdout(cmd)
 	default:
 		relay := filepath.Join(paths.BaseUnix, "bin", toolRelayName)
@@ -100,6 +101,7 @@ func Run(tool string, args []string) int {
 			cmd := exec.Command(wineBin, append([]string{toolExePath}, rewritten...)...)
 			cmd.Env = buildEnv(paths)
 			cmd.Stdin = os.Stdin
+			setNewProcessGroup(cmd)
 			exitCode = runFiltered(cmd, s.stdoutFilter, s.stderrFilter)
 		}
 	}
@@ -137,6 +139,7 @@ func runViaToolRelay(wineBin, relayExe, exePath string, args []string, paths *wi
 	cmdArgs := append([]string{relayExe, exePath}, args...)
 	cmd := exec.Command(wineBin, cmdArgs...)
 	cmd.Env = append(buildEnv(paths), "MSVCGOWINE_STDOUT="+stdoutFifo, "MSVCGOWINE_STDERR="+stderrFifo)
+	setNewProcessGroup(cmd)
 	if devNull, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0); err == nil {
 		defer devNull.Close()
 		cmd.Stdout = devNull
@@ -147,6 +150,8 @@ func runViaToolRelay(wineBin, relayExe, exePath string, args []string, paths *wi
 		fmt.Fprintln(os.Stderr, "vintner:", err)
 		return 1
 	}
+	stopSignals := forwardSignals(cmd.Process)
+	defer stopSignals()
 
 	var wg sync.WaitGroup
 	wg.Add(2)
@@ -204,6 +209,8 @@ func runRawStdout(cmd *exec.Cmd) int {
 		fmt.Fprintln(os.Stderr, "vintner:", err)
 		return 1
 	}
+	stopSignals := forwardSignals(cmd.Process)
+	defer stopSignals()
 
 	doneOut := make(chan struct{})
 	doneErr := make(chan struct{})
@@ -278,6 +285,8 @@ func runFiltered(cmd *exec.Cmd, stdoutF, stderrF lineFilter) int {
 		fmt.Fprintln(os.Stderr, "vintner:", err)
 		return 1
 	}
+	stopSignals := forwardSignals(cmd.Process)
+	defer stopSignals()
 
 	doneOut := make(chan struct{})
 	doneErr := make(chan struct{})
@@ -310,4 +319,11 @@ 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)
+	}
 }

internal/wrapper/signals.go

@@ -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)
+	}
+}

internal/wrapper/signals_test.go

@@ -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")
+	}
+}

internal/wrapper/tools_test.go

@@ -0,0 +1,45 @@
+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)
+		}
+	}
+}