herdrdev · ogulcancelik · Aug 14, 2026 · Aug 14, 2026
diff --git a/Cargo.toml b/Cargo.toml
@@ -14,6 +14,7 @@ include = [
     "assets/sounds/*",
     "docs/next/api/herdr-api.schema.json",
     "skills/herdr/SKILL.md",
+    "website/install.ps1",
     "README.md",
     "LICENSE",
     "Cargo.toml",

diff --git a/scripts/windows_install_conpty_package_test.ps1 b/scripts/windows_install_conpty_package_test.ps1
@@ -113,10 +113,56 @@ try {
         }
     }
 
-    & "$PSScriptRoot\..\website\install.ps1" `
-        -ManifestUrl $manifestUrl `
-        -InstallDir $installDir `
-        -ExpectedBuildId "installer-test"
+    # Keep the existing positional web-installer contract, including Retain in slot five.
+    & "$PSScriptRoot\..\website\install.ps1" "preview" $manifestUrl $installDir "installer-test" 3
+
+    $localInstallDir = Join-Path $root "local-bin"
+    $env:HERDR_HOME = Join-Path $root "local-home"
+    $partialLocalModeRejected = $false
+    try {
+        & $installerPath `
+            -InstallDir $localInstallDir `
+            -LocalPackagePath $archive
+    } catch {
+        if ($_.Exception.Message -notlike "Local package mode requires*") {
+            throw
+        }
+        $partialLocalModeRejected = $true
+    }
+    if (-not $partialLocalModeRejected) {
+        throw "installer accepted partial local-package inputs"
+    }
+
+    $badLocalChecksumRejected = $false
+    try {
+        & $installerPath `
+            -ManifestUrl "$manifestUrl/unused" `
+            -InstallDir $localInstallDir `
+            -LocalPackagePath $archive `
+            -LocalPackageFormat "zip" `
+            -LocalPackageIdentity "0.0.0-preview.local-package" `
+            -LocalPackageSha256 ("0" * 64)
+    } catch {
+        if ($_.Exception.Message -notlike "Downloaded Herdr checksum did not match.*") {
+            throw
+        }
+        $badLocalChecksumRejected = $true
+    }
+    if (-not $badLocalChecksumRejected) {
+        throw "installer accepted a local package with the wrong checksum"
+    }
+
+    & $installerPath `
+        -ManifestUrl "$manifestUrl/unused" `
+        -InstallDir $localInstallDir `
+        -LocalPackagePath $archive `
+        -LocalPackageFormat "zip" `
+        -LocalPackageIdentity "0.0.0-preview.local-package" `
+        -LocalPackageSha256 $hash
+    if (-not (Test-Path -LiteralPath (Join-Path $localInstallDir "herdr.exe") -PathType Leaf)) {
+        throw "installer did not activate the verified local package"
+    }
+    $env:HERDR_HOME = $herdrHome
 
     $required = @(
         "herdr.exe",

diff --git a/src/update.rs b/src/update.rs
@@ -8,7 +8,6 @@
 
 use std::collections::BTreeMap;
 use std::env;
-#[cfg(not(windows))]
 use std::fs;
 #[cfg(not(windows))]
 use std::io;
@@ -125,6 +124,8 @@ impl UpdateChannel {
 struct AssetRef {
     url: String,
     sha256: Option<String>,
+    #[cfg(windows)]
+    format: Option<String>,
 }
 
 impl<'de> Deserialize<'de> for AssetRef {
@@ -137,6 +138,8 @@ impl<'de> Deserialize<'de> for AssetRef {
             serde_json::Value::String(url) if !url.trim().is_empty() => Ok(Self {
                 url: url.trim().to_string(),
                 sha256: None,
+                #[cfg(windows)]
+                format: None,
             }),
             serde_json::Value::Object(mut object) => {
                 let url = object
@@ -146,12 +149,18 @@ impl<'de> Deserialize<'de> for AssetRef {
                 let sha256 = object
                     .remove("sha256")
                     .and_then(|value| value.as_str().map(str::to_string));
+                #[cfg(windows)]
+                let format = object
+                    .remove("format")
+                    .and_then(|value| value.as_str().map(str::to_string));
                 if url.trim().is_empty() {
                     return Err(serde::de::Error::custom("asset url must not be empty"));
                 }
                 Ok(Self {
                     url: url.trim().to_string(),
                     sha256: sha256.filter(|value| !value.trim().is_empty()),
+                    #[cfg(windows)]
+                    format: format.filter(|value| !value.trim().is_empty()),
                 })
             }
             _ => Err(serde::de::Error::custom(
@@ -161,6 +170,30 @@ impl<'de> Deserialize<'de> for AssetRef {
     }
 }
 
+#[cfg(windows)]
+impl AssetRef {
+    fn package_format(&self) -> Result<String, String> {
+        let format = self
+            .format
+            .clone()
+            .unwrap_or_else(|| {
+                if self.url.to_ascii_lowercase().ends_with(".zip") {
+                    "zip"
+                } else {
+                    "exe"
+                }
+                .into()
+            })
+            .to_ascii_lowercase();
+        match format.as_str() {
+            "zip" | "exe" => Ok(format),
+            _ => Err(format!(
+                "update manifest asset has unsupported format '{format}'"
+            )),
+        }
+    }
+}
+
 #[derive(Deserialize)]
 struct UpdateManifest {
     version: String,
@@ -275,6 +308,8 @@ struct ReleaseInfo {
     target_protocol: Option<u32>,
     download_url: String,
     sha256: Option<String>,
+    #[cfg(windows)]
+    package_format: String,
     notes_body: String,
 }
 
@@ -382,6 +417,8 @@ fn release_info_from_manifest(manifest: &UpdateManifest) -> Result<Option<Releas
         target_protocol: manifest.protocol,
         download_url,
         sha256: Some(sha256),
+        #[cfg(windows)]
+        package_format: asset.package_format()?,
         notes_body,
     }))
 }
@@ -467,6 +504,8 @@ fn release_info_from_preview_manifest(
         target_protocol: Some(manifest.protocol),
         download_url,
         sha256: asset.sha256.clone(),
+        #[cfg(windows)]
+        package_format: asset.package_format()?,
         notes_body,
     }))
 }
@@ -636,30 +675,82 @@ fn install_downloaded_update(mut update: DownloadedUpdate) -> Result<(), String>
     Ok(())
 }
 
+#[cfg(windows)]
+const WINDOWS_INSTALLER: &str = include_str!("../website/install.ps1");
+
+#[cfg(windows)]
+struct DownloadedWindowsUpdate {
+    package_path: PathBuf,
+    installer_path: PathBuf,
+}
+
+#[cfg(windows)]
+impl Drop for DownloadedWindowsUpdate {
+    fn drop(&mut self) {
+        let _ = fs::remove_file(&self.package_path);
+        let _ = fs::remove_file(&self.installer_path);
+    }
+}
+
+#[cfg(windows)]
+fn download_windows_update(release: &ReleaseInfo) -> Result<DownloadedWindowsUpdate, String> {
+    let expected_sha256 = release
+        .sha256
+        .as_deref()
+        .ok_or("Windows update asset is missing a SHA-256 checksum")?;
+    let stem = format!("herdr-update-{}", std::process::id());
+    let update = DownloadedWindowsUpdate {
+        package_path: env::temp_dir().join(format!("{stem}.{}", release.package_format)),
+        installer_path: env::temp_dir().join(format!("{stem}.ps1")),
+    };
+    fs::write(&update.installer_path, WINDOWS_INSTALLER)
+        .map_err(|err| format!("failed to prepare Windows installer: {err}"))?;
+
+    let status = crate::noninteractive_process::curl_command()
+        .args(["-sfL", "--max-time", "120", "-o"])
+        .arg(&update.package_path)
+        .arg(&release.download_url)
+        .status()
+        .map_err(|err| format!("download failed: {err}"))?;
+    if !status.success() {
+        return Err("download failed".into());
+    }
+    crate::checksum::verify_sha256(&update.package_path, expected_sha256)
+        .map_err(|err| format!("downloaded update checksum verification failed: {err}"))?;
+    tracing::info!(sha256 = %expected_sha256, "downloaded update checksum verified");
+
+    Ok(update)
+}
+
 #[cfg(windows)]
 fn install_windows_update_with_installer(
-    channel: UpdateChannel,
-    expected_build_id: Option<&str>,
+    release: &ReleaseInfo,
+    update: &DownloadedWindowsUpdate,
 ) -> Result<(), String> {
+    let expected_sha256 = release
+        .sha256
+        .as_deref()
+        .ok_or("Windows update asset is missing a SHA-256 checksum")?;
     let mut command = Command::new("powershell");
     command
+        .args(["-NoProfile", "-ExecutionPolicy", "Bypass", "-File"])
+        .arg(&update.installer_path)
+        .args(["-Channel", release.channel.as_str(), "-LocalPackagePath"])
+        .arg(&update.package_path)
         .args([
-            "-NoProfile",
-            "-ExecutionPolicy",
-            "Bypass",
-            "-Command",
-            "irm https://herdr.dev/install.ps1 | iex",
+            "-LocalPackageFormat",
+            &release.package_format,
+            "-LocalPackageIdentity",
+            release.label(),
+            "-LocalPackageSha256",
+            expected_sha256,
         ])
-        .env("HERDR_CHANNEL", channel.as_str())
         // Drop any inherited PSModulePath. When herdr is launched from
         // PowerShell 7, its Core module paths come first and Windows
         // PowerShell 5.1 (this `powershell`) fails to autoload cmdlets like
         // Get-FileHash. Removing it lets 5.1 compute its own default path.
         // See PowerShell/PowerShell#8635.
         .env_remove("PSModulePath");
-    if let Some(build_id) = expected_build_id {
-        command.env("HERDR_EXPECTED_BUILD_ID", build_id);
-    }
     let status = command
         .status()
         .map_err(|err| format!("failed to run Windows installer: {err}"))?;
@@ -2041,7 +2132,10 @@ pub fn self_update(options: SelfUpdateOptions) -> Result<Version, String> {
         if let Some(sha256) = &release.sha256 {
             tracing::debug!(sha256 = %sha256, "selected Windows update asset has checksum");
         }
-        install_windows_update_with_installer(channel, release.build_id.as_deref())?;
+        eprintln!("downloading {}...", release.label());
+        let downloaded_update = download_windows_update(&release)?;
+        eprintln!("downloaded {}", release.label());
+        install_windows_update_with_installer(&release, &downloaded_update)?;
         let updated_exe = windows_installed_herdr_exe_path()?;
         eprintln!("installed {}", release.label());
         print_outdated_integration_notice_with_updated_binary(&updated_exe);

diff --git a/website/install.ps1 b/website/install.ps1
@@ -4,7 +4,11 @@ param(
     [string]$ManifestUrl = $env:HERDR_MANIFEST_URL,
     [string]$InstallDir = $env:HERDR_INSTALL_DIR,
     [string]$ExpectedBuildId = $env:HERDR_EXPECTED_BUILD_ID,
-    [int]$Retain = 3
+    [int]$Retain = 3,
+    [string]$LocalPackagePath,
+    [string]$LocalPackageFormat,
+    [string]$LocalPackageIdentity,
+    [string]$LocalPackageSha256
 )
 
 Set-StrictMode -Version Latest
@@ -20,6 +24,21 @@ if ($Channel -notin @("stable", "preview")) {
     exit 1
 }
 
+$localPackageValueCount = @(
+    $LocalPackagePath,
+    $LocalPackageFormat,
+    $LocalPackageIdentity,
+    $LocalPackageSha256 |
+        Where-Object { -not [string]::IsNullOrWhiteSpace($_) }
+).Count
+if ($localPackageValueCount -notin @(0, 4)) {
+    throw "Local package mode requires path, format, identity, and SHA-256."
+}
+$useLocalPackage = $localPackageValueCount -eq 4
+if ($useLocalPackage -and $LocalPackageFormat -notin @("zip", "exe")) {
+    throw "Local Herdr package has unsupported format '$LocalPackageFormat'."
+}
+
 function Write-Step {
     param([string]$Message)
     Write-Host "==> $Message"
@@ -548,7 +567,7 @@ switch ($architecture) {
     }
 }
 
-if ([string]::IsNullOrWhiteSpace($ManifestUrl)) {
+if (-not $useLocalPackage -and [string]::IsNullOrWhiteSpace($ManifestUrl)) {
     $ManifestUrl = if ($Channel -eq "preview") {
         "https://herdr.dev/preview.json"
     } else {
@@ -589,13 +608,21 @@ if (-not [string]::IsNullOrWhiteSpace($existingHerdr) -and -not (Test-PathStarts
     Write-WarningStep "PATH order decides which Herdr runs. This installer will put $visibleBinDir first for future and current PowerShell sessions."
 }
 
-Write-Step "Fetching Herdr $Channel manifest"
-$manifest = ConvertTo-ManifestObject -Manifest (Invoke-RestMethod -Uri $ManifestUrl)
-if (-not [string]::IsNullOrWhiteSpace($ExpectedBuildId) -and [string]$manifest.build_id -ne $ExpectedBuildId) {
-    throw "Preview manifest changed while updating. Expected build $ExpectedBuildId but found $($manifest.build_id). Run herdr update again."
+if ($useLocalPackage) {
+    $versionIdentity = $LocalPackageIdentity
+    $asset = [PSCustomObject]@{
+        Sha256 = $LocalPackageSha256
+        Format = $LocalPackageFormat
+    }
+} else {
+    Write-Step "Fetching Herdr $Channel manifest"
+    $manifest = ConvertTo-ManifestObject -Manifest (Invoke-RestMethod -Uri $ManifestUrl)
+    if (-not [string]::IsNullOrWhiteSpace($ExpectedBuildId) -and [string]$manifest.build_id -ne $ExpectedBuildId) {
+        throw "Preview manifest changed while updating. Expected build $ExpectedBuildId but found $($manifest.build_id). Run herdr update again."
+    }
+    $versionIdentity = Resolve-HerdrVersion -Manifest $manifest -SelectedChannel $Channel
+    $asset = Get-ManifestAsset -Manifest $manifest -Target $target
 }
-$versionIdentity = Resolve-HerdrVersion -Manifest $manifest -SelectedChannel $Channel
-$asset = Get-ManifestAsset -Manifest $manifest -Target $target
 $safeVersionIdentity = $versionIdentity -replace '[^0-9A-Za-z._-]', '-'
 $releaseName = "$safeVersionIdentity-$targetTriple"
 $releaseDir = Join-Path $releasesDir $releaseName
@@ -609,10 +636,16 @@ try {
         Remove-StaleInstallArtifacts -ReleasesDir $releasesDir
 
         if (-not (Test-HerdrReleaseComplete -ReleaseDir $releaseDir -Format $asset.Format)) {
-            $downloadPath = Join-Path $tempDir "herdr-download.$($asset.Format)"
+            $downloadPath = if ($useLocalPackage) {
+                $LocalPackagePath
+            } else {
+                Join-Path $tempDir "herdr-download.$($asset.Format)"
+            }
             $stagingDir = Join-Path $releasesDir ".staging.$releaseName.$PID"
-            Write-Step "Downloading Herdr"
-            Invoke-WebRequest -Uri $asset.Url -OutFile $downloadPath
+            if (-not $useLocalPackage) {
+                Write-Step "Downloading Herdr"
+                Invoke-WebRequest -Uri $asset.Url -OutFile $downloadPath
+            }
             Test-FileDigest -Path $downloadPath -ExpectedDigest $asset.Sha256
 
             if ($asset.Format -eq "zip") {