diff --git a/scripts/build-tht.sh b/scripts/build-tht.sh
index b3a15fbb..27231ff8 100755
--- a/scripts/build-tht.sh
+++ b/scripts/build-tht.sh
@@ -5,6 +5,36 @@ export DOCKER_BUILDKIT=1
 repository_root=$(cd "$(dirname "$0")/.." && pwd)
 output_directory="${THT_THT_OUTPUT_DIRECTORY:-$repository_root/dist/tht}"
 
+usage() {
+  cat <<'EOF'
+Usage: bash scripts/build-tht.sh [--all] [--output ABSOLUTE_DIRECTORY]
+
+Build every supported native tht binary with the repository-pinned Docker builder.
+EOF
+}
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --all)
+      ;;
+    --output)
+      [[ $# -ge 2 ]] || { echo "--output requires an absolute directory" >&2; exit 2; }
+      output_directory=$2
+      shift
+      ;;
+    --help|-h)
+      usage
+      exit 0
+      ;;
+    *)
+      echo "unknown argument: $1" >&2
+      usage >&2
+      exit 2
+      ;;
+  esac
+  shift
+done
+
 if [[ "$output_directory" != /* || "$output_directory" == / || "$output_directory" == */ ||
       "$output_directory" == *//* || "/$output_directory/" == */../* ||
       "/$output_directory/" == */./* ]]; then
diff --git a/scripts/install-tht.ps1 b/scripts/install-tht.ps1
new file mode 100644
index 00000000..9374d0b4
--- /dev/null
+++ b/scripts/install-tht.ps1
@@ -0,0 +1,104 @@
+[CmdletBinding()]
+param()
+
+Set-StrictMode -Version Latest
+$ErrorActionPreference = 'Stop'
+
+function Get-Sha256([string]$Path) {
+    return (Get-FileHash -Algorithm SHA256 -LiteralPath $Path).Hash.ToLowerInvariant()
+}
+
+function Get-UserPathValue {
+    if ($env:THT_USER_PATH_FILE) {
+        if (Test-Path -LiteralPath $env:THT_USER_PATH_FILE) {
+            return [System.IO.File]::ReadAllText($env:THT_USER_PATH_FILE)
+        }
+        return ''
+    }
+    return [Environment]::GetEnvironmentVariable('Path', 'User')
+}
+
+function Set-UserPathValue([string]$Value) {
+    if ($env:THT_USER_PATH_FILE) {
+        [System.IO.File]::WriteAllText($env:THT_USER_PATH_FILE, $Value)
+        return
+    }
+    [Environment]::SetEnvironmentVariable('Path', $Value, 'User')
+}
+
+function Add-InstallDirectoryToUserPath([string]$InstallDirectory) {
+    $currentPath = Get-UserPathValue
+    $entries = @($currentPath -split ';' | Where-Object { $_ -ne '' })
+    if ($entries | Where-Object { $_.TrimEnd('\\') -ieq $InstallDirectory.TrimEnd('\\') }) {
+        return $false
+    }
+    $newPath = (@($entries) + $InstallDirectory) -join ';'
+    Set-UserPathValue $newPath
+    return $true
+}
+
+$repositoryRoot = Split-Path -Parent $PSScriptRoot
+$buildOutput = $null
+$sourceArtifactForInstall = $null
+$installDirectory = if ($env:THT_INSTALL_DIRECTORY) {
+    $env:THT_INSTALL_DIRECTORY
+} else {
+    Join-Path $env:LOCALAPPDATA 'ThothII\bin'
+}
+$installDirectory = [System.IO.Path]::GetFullPath($installDirectory)
+
+if ($env:THT_BUILD_ARTIFACT) {
+    $sourceArtifact = $env:THT_BUILD_ARTIFACT
+    if (-not (Test-Path -LiteralPath $sourceArtifact -PathType Leaf)) {
+        throw 'THT_BUILD_ARTIFACT is not a regular file'
+    }
+    if (-not $env:THT_BUILD_ARTIFACT_SHA256 -or $env:THT_BUILD_ARTIFACT_SHA256 -notmatch '^[0-9A-Fa-f]{64}$') {
+        throw 'THT_BUILD_ARTIFACT_SHA256 must be a 64-character SHA-256 digest'
+    }
+    if ((Get-Sha256 $sourceArtifact) -ne $env:THT_BUILD_ARTIFACT_SHA256.ToLowerInvariant()) {
+        throw 'packaged tht artifact checksum does not match'
+    }
+    $sourceArtifactForInstall = $sourceArtifact
+} else {
+    if ($env:PROCESSOR_ARCHITECTURE -notin @('AMD64', 'x86_64')) {
+        throw "unsupported Windows processor architecture: $env:PROCESSOR_ARCHITECTURE (supported: AMD64)"
+    }
+    $buildOutput = Join-Path ([System.IO.Path]::GetTempPath()) ("tht-build-" + [guid]::NewGuid())
+    New-Item -ItemType Directory -Path $buildOutput -Force | Out-Null
+    $previousOutput = $env:THT_THT_OUTPUT_DIRECTORY
+    $env:THT_THT_OUTPUT_DIRECTORY = $buildOutput
+    try {
+        & bash (Join-Path $repositoryRoot 'scripts/build-tht.sh') --all
+        if ($LASTEXITCODE -ne 0) { throw 'the repository-pinned Docker build failed' }
+    } finally {
+        $env:THT_THT_OUTPUT_DIRECTORY = $previousOutput
+    }
+    $sourceArtifactForInstall = Join-Path $buildOutput 'tht-windows-amd64.exe'
+    if (-not (Test-Path -LiteralPath $sourceArtifactForInstall -PathType Leaf)) {
+        throw 'the repository-pinned Docker build did not produce tht-windows-amd64.exe'
+    }
+}
+
+if ((Get-Item -LiteralPath $sourceArtifactForInstall).Length -eq 0) { throw 'native artifact is empty' }
+New-Item -ItemType Directory -Path $installDirectory -Force | Out-Null
+$stagedBinary = Join-Path $installDirectory ('.tht-' + [guid]::NewGuid() + '.exe')
+try {
+    Copy-Item -LiteralPath $sourceArtifactForInstall -Destination $stagedBinary -Force
+    & $stagedBinary --help | Out-Null
+    if ($LASTEXITCODE -ne 0) { throw 'native artifact did not pass its help check' }
+    Move-Item -LiteralPath $stagedBinary -Destination (Join-Path $installDirectory 'tht.exe') -Force
+} finally {
+    Remove-Item -LiteralPath $stagedBinary -Force -ErrorAction SilentlyContinue
+    if ($buildOutput) { Remove-Item -LiteralPath $buildOutput -Recurse -Force -ErrorAction SilentlyContinue }
+}
+
+$pathChanged = Add-InstallDirectoryToUserPath $installDirectory
+if ($env:Path -notlike "*$installDirectory*") {
+    $env:Path = "$installDirectory;$env:Path"
+}
+& (Join-Path $installDirectory 'tht.exe') --help | Out-Null
+if ($LASTEXITCODE -ne 0) { throw 'installed tht did not pass its help check' }
+Write-Output "Installed tht at $(Join-Path $installDirectory 'tht.exe')"
+if ($pathChanged) {
+    Write-Output 'Added ThothII to your user PATH. Open a new terminal before using tht there.'
+}
diff --git a/scripts/install-tht.sh b/scripts/install-tht.sh
new file mode 100644
index 00000000..d59db5ca
--- /dev/null
+++ b/scripts/install-tht.sh
@@ -0,0 +1,101 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repository_root=$(cd "$(dirname "$0")/.." && pwd)
+install_directory="${THT_INSTALL_DIRECTORY:-/usr/local/bin}"
+staging_root=$(mktemp -d)
+trap 'rm -rf "$staging_root"' EXIT HUP INT TERM
+
+fail() {
+  echo "install-tht.sh: $*" >&2
+  exit 1
+}
+
+sha256() {
+  if command -v sha256sum >/dev/null 2>&1; then
+    sha256sum "$1" | awk '{print $1}'
+  elif command -v shasum >/dev/null 2>&1; then
+    shasum -a 256 "$1" | awk '{print $1}'
+  else
+    fail "SHA-256 verification requires sha256sum or shasum"
+  fi
+}
+
+platform_artifact_name() {
+  local system architecture
+  system=$(uname -s)
+  architecture=$(uname -m)
+  case "$system" in
+    Darwin) system=darwin ;;
+    Linux) system=linux ;;
+    *) fail "unsupported operating system: $system (supported: macOS and Linux)" ;;
+  esac
+  case "$architecture" in
+    x86_64|amd64) architecture=amd64 ;;
+    arm64|aarch64) architecture=arm64 ;;
+    *) fail "unsupported processor architecture: $architecture (supported: amd64 and arm64)" ;;
+  esac
+  printf 'tht-%s-%s\n' "$system" "$architecture"
+}
+
+validate_packaged_artifact() {
+  local artifact=$1 expected actual
+  expected=${THT_BUILD_ARTIFACT_SHA256:-}
+  [[ "$expected" =~ ^[[:xdigit:]]{64}$ ]] || fail "THT_BUILD_ARTIFACT_SHA256 must be a 64-character SHA-256 digest"
+  actual=$(sha256 "$artifact")
+  [[ "${actual,,}" == "${expected,,}" ]] || fail "packaged tht artifact checksum does not match"
+}
+
+build_artifact() {
+  local build_output="$staging_root/build"
+  mkdir -p "$build_output"
+  THT_THT_OUTPUT_DIRECTORY="$build_output" bash "$repository_root/scripts/build-tht.sh" --all >&2
+  printf '%s/%s\n' "$build_output" "$(platform_artifact_name)"
+}
+
+install_atomically() {
+  local destination_directory=$1 source_file=$2
+  local temporary_destination
+  if mkdir -p "$destination_directory" 2>/dev/null && [[ -w "$destination_directory" ]]; then
+    temporary_destination=$(mktemp "$destination_directory/.tht.XXXXXX")
+    cp "$source_file" "$temporary_destination"
+    chmod 0755 "$temporary_destination"
+    mv -f "$temporary_destination" "$destination_directory/tht"
+    return
+  fi
+
+  command -v sudo >/dev/null 2>&1 || fail "cannot write to $destination_directory and sudo is unavailable"
+  sudo sh -c '
+    set -eu
+    destination_directory=$1
+    source_file=$2
+    mkdir -p "$destination_directory"
+    temporary_destination=$(mktemp "$destination_directory/.tht.XXXXXX")
+    trap "rm -f \"$temporary_destination\"" EXIT HUP INT TERM
+    cp "$source_file" "$temporary_destination"
+    chmod 0755 "$temporary_destination"
+    mv -f "$temporary_destination" "$destination_directory/tht"
+  ' sh "$destination_directory" "$source_file"
+}
+
+[[ "$install_directory" == /* ]] || fail "THT_INSTALL_DIRECTORY must be an absolute path"
+artifact_name=$(platform_artifact_name)
+if [[ -n "${THT_BUILD_ARTIFACT:-}" ]]; then
+  source_artifact=$THT_BUILD_ARTIFACT
+  [[ -f "$source_artifact" ]] || fail "THT_BUILD_ARTIFACT is not a regular file"
+  validate_packaged_artifact "$source_artifact"
+else
+  source_artifact=$(build_artifact)
+fi
+
+[[ -s "$source_artifact" ]] || fail "native artifact is missing: $artifact_name"
+staged_binary="$staging_root/tht"
+cp "$source_artifact" "$staged_binary"
+chmod 0755 "$staged_binary"
+"$staged_binary" --help >/dev/null || fail "native artifact did not pass its help check"
+
+install_atomically "$install_directory" "$staged_binary"
+resolved_command=$(command -v tht || true)
+[[ "$resolved_command" == "$install_directory/tht" ]] || fail "installed tht is not resolvable at $install_directory/tht; add $install_directory to PATH and open a new terminal"
+"$install_directory/tht" --help >/dev/null || fail "installed tht did not pass its help check"
+printf 'Installed tht at %s/tht\n' "$install_directory"
diff --git a/scripts/test-install-tht.ps1 b/scripts/test-install-tht.ps1
new file mode 100644
index 00000000..edd5c11c
--- /dev/null
+++ b/scripts/test-install-tht.ps1
@@ -0,0 +1,69 @@
+$ErrorActionPreference = 'Stop'
+
+$repositoryRoot = Split-Path -Parent $PSScriptRoot
+$installer = Join-Path $repositoryRoot 'scripts/install-tht.ps1'
+if (-not (Test-Path -LiteralPath $installer)) {
+    throw "installer is missing: $installer"
+}
+
+$isWindowsHost = $env:OS -eq 'Windows_NT'
+if (-not $isWindowsHost) {
+    $installerText = Get-Content -LiteralPath $installer -Raw
+    foreach ($requiredText in @('THT_INSTALL_DIRECTORY', 'LOCALAPPDATA', 'SetEnvironmentVariable', 'build-tht.sh', 'Move-Item')) {
+        if (-not $installerText.Contains($requiredText)) {
+            throw "Windows installer is missing required behavior: $requiredText"
+        }
+    }
+    Write-Output 'PowerShell installer behavior test skipped: requires Windows.'
+    exit 0
+}
+
+$temporaryRoot = Join-Path ([System.IO.Path]::GetTempPath()) ("tht installer test {0}" -f [guid]::NewGuid())
+$installDirectory = Join-Path $temporaryRoot 'command directory'
+$artifact = Join-Path $temporaryRoot 'tht.exe'
+$userPathStore = Join-Path $temporaryRoot 'user-path.txt'
+New-Item -ItemType Directory -Path $temporaryRoot -Force | Out-Null
+try {
+    $program = @'
+using System;
+public static class Program {
+    public static void Main(string[] args) {
+        if (args.Length == 1 && args[0] == "--help") { Console.WriteLine("Usage: tht"); return; }
+        if (args.Length == 1 && args[0] == "version") { Console.WriteLine("tht test version"); return; }
+        Environment.Exit(2);
+    }
+}
+'@
+    Add-Type -TypeDefinition $program -OutputAssembly $artifact -OutputType ConsoleApplication
+    [System.IO.File]::WriteAllText($userPathStore, 'C:\Existing Bin')
+
+    $env:THT_INSTALL_DIRECTORY = $installDirectory
+    $env:THT_BUILD_ARTIFACT = $artifact
+    $env:THT_BUILD_ARTIFACT_SHA256 = (Get-FileHash -Algorithm SHA256 -LiteralPath $artifact).Hash.ToLowerInvariant()
+    $env:THT_USER_PATH_FILE = $userPathStore
+    & $installer
+
+    $installed = Join-Path $installDirectory 'tht.exe'
+    if (-not (Test-Path -LiteralPath $installed)) { throw 'installer did not create tht.exe' }
+    if ((& $installed version) -ne 'tht test version') { throw 'installed tht.exe did not return version' }
+    $firstBytes = [System.IO.File]::ReadAllBytes($installed)
+
+    & $installer
+    if ((& $installed version) -ne 'tht test version') { throw 'installer was not idempotent' }
+    if (-not ([System.IO.File]::ReadAllBytes($installed).Length -eq $firstBytes.Length)) { throw 'replacement changed the unexpected binary' }
+
+    $storedPath = [System.IO.File]::ReadAllText($userPathStore)
+    $segments = $storedPath -split ';' | Where-Object { $_ -ne '' }
+    if ((@($segments | Where-Object { $_ -ieq $installDirectory }).Count) -ne 1) {
+        throw 'installer did not preserve a single destination PATH entry'
+    }
+    if (-not ($segments | Where-Object { $_ -ieq 'C:\Existing Bin' })) { throw 'installer did not preserve existing user PATH entries' }
+    Write-Output 'PowerShell tht installer tests passed.'
+}
+finally {
+    Remove-Item Env:THT_INSTALL_DIRECTORY -ErrorAction SilentlyContinue
+    Remove-Item Env:THT_BUILD_ARTIFACT -ErrorAction SilentlyContinue
+    Remove-Item Env:THT_BUILD_ARTIFACT_SHA256 -ErrorAction SilentlyContinue
+    Remove-Item Env:THT_USER_PATH_FILE -ErrorAction SilentlyContinue
+    Remove-Item -LiteralPath $temporaryRoot -Recurse -Force -ErrorAction SilentlyContinue
+}
diff --git a/scripts/test-install-tht.sh b/scripts/test-install-tht.sh
new file mode 100644
index 00000000..58b9ca5c
--- /dev/null
+++ b/scripts/test-install-tht.sh
@@ -0,0 +1,81 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repository_root=$(cd "$(dirname "$0")/.." && pwd)
+installer="$repository_root/scripts/install-tht.sh"
+temporary_root=$(mktemp -d)
+trap 'rm -rf "$temporary_root"' EXIT HUP INT TERM
+
+fail() {
+  echo "test-install-tht.sh: $*" >&2
+  exit 1
+}
+
+sha256() {
+  if command -v sha256sum >/dev/null 2>&1; then
+    sha256sum "$1" | awk '{print $1}'
+  else
+    shasum -a 256 "$1" | awk '{print $1}'
+  fi
+}
+
+write_artifact() {
+  local path=$1
+  local version=$2
+  cat >"$path" <<EOF
+#!/usr/bin/env bash
+set -euo pipefail
+case "\${1:-}" in
+  --help|-h) echo "Usage: tht" ;;
+  version) echo "$version" ;;
+  *) echo "unexpected argument: \${1:-}" >&2; exit 2 ;;
+esac
+EOF
+  chmod 0644 "$path"
+}
+
+test_directory="$temporary_root/command directory"
+artifact_one="$temporary_root/tht-one"
+artifact_two="$temporary_root/tht-two"
+write_artifact "$artifact_one" "tht test version one"
+write_artifact "$artifact_two" "tht test version two"
+
+system_path=$PATH
+run_installer() {
+  local artifact=$1
+  THT_INSTALL_DIRECTORY="$test_directory" \
+    THT_BUILD_ARTIFACT="$artifact" \
+    THT_BUILD_ARTIFACT_SHA256="$(sha256 "$artifact")" \
+    PATH="$test_directory:$system_path" \
+    bash "$installer"
+}
+
+run_installer "$artifact_one"
+
+test -x "$test_directory/tht" || fail "installed tht is not executable"
+first_inode=$(stat -f '%i' "$test_directory/tht" 2>/dev/null || stat -c '%i' "$test_directory/tht")
+first_version=$(PATH="$test_directory:$system_path" tht version)
+test "$first_version" = "tht test version one" || fail "installed command did not run version one"
+
+run_installer "$artifact_two"
+second_inode=$(stat -f '%i' "$test_directory/tht" 2>/dev/null || stat -c '%i' "$test_directory/tht")
+second_version=$(PATH="$test_directory:$system_path" tht version)
+test "$second_version" = "tht test version two" || fail "replacement did not install version two"
+test "$first_inode" != "$second_inode" || fail "replacement did not atomically replace the destination"
+
+run_installer "$artifact_two"
+third_version=$(PATH="$test_directory:$system_path" tht version)
+test "$third_version" = "tht test version two" || fail "re-running installer was not idempotent"
+
+if THT_INSTALL_DIRECTORY="$test_directory" \
+  THT_BUILD_ARTIFACT="$artifact_one" \
+  THT_BUILD_ARTIFACT_SHA256="not-a-checksum" \
+  PATH="$test_directory:$system_path" \
+  bash "$installer" >/dev/null 2>&1; then
+  fail "installer accepted a checksum mismatch"
+fi
+
+after_failed_checksum=$(PATH="$test_directory:$system_path" tht version)
+test "$after_failed_checksum" = "tht test version two" || fail "failed install replaced the existing command"
+
+echo "shell tht installer tests passed."