fix(installer): preserve healthy Python runtime and Codex connections

scripts/install.ps1

@@ -2550,6 +2550,39 @@ function Install-Repository {
     Write-Success "Repository ready"
 }
 
+function Test-ReusableManagedVenv {
+    param([string]$VenvPath, [string]$BasePython, [string]$Version)
+    $pythonExe = Join-Path $VenvPath "Scripts\python.exe"
+    if (-not (Test-Path -LiteralPath $pythonExe -PathType Leaf)) { return $false }
+    $process = New-Object System.Diagnostics.Process
+    try {
+        $info = New-Object System.Diagnostics.ProcessStartInfo
+        $info.FileName = $pythonExe
+        $info.Arguments = '-I -c "import json,sys,ssl,ctypes,venv,encodings; print(json.dumps(dict(version=str(sys.version_info.major)+''.''+str(sys.version_info.minor),prefix=sys.prefix,base=sys._base_executable)))"'
+        $info.UseShellExecute = $false
+        $info.CreateNoWindow = $true
+        $info.RedirectStandardOutput = $true
+        $info.RedirectStandardError = $true
+        $process.StartInfo = $info
+        if (-not $process.Start()) { return $false }
+        $stdout = $process.StandardOutput.ReadToEndAsync()
+        $stderr = $process.StandardError.ReadToEndAsync()
+        if (-not $process.WaitForExit(15000)) {
+            try { $process.Kill() } catch { }
+            return $false
+        }
+        if ($process.ExitCode -ne 0) { return $false }
+        $health = $stdout.Result | ConvertFrom-Json
+        return ($health.version -eq $Version -and
+            [string]::Equals([IO.Path]::GetFullPath($health.prefix), [IO.Path]::GetFullPath($VenvPath), [StringComparison]::OrdinalIgnoreCase) -and
+            [string]::Equals([IO.Path]::GetFullPath($health.base), [IO.Path]::GetFullPath($BasePython), [StringComparison]::OrdinalIgnoreCase))
+    } catch {
+        return $false
+    } finally {
+        $process.Dispose()
+    }
+}
+
 function Install-Venv {
     if ($NoVenv) {
         Write-Info "Skipping virtual environment (-NoVenv)"
@@ -2567,6 +2600,19 @@ function Install-Venv {
         throw "Hermes-managed Python is unavailable. Run install.ps1 -Stage python first."
     }
 
+    # Routine source updates do not require replacing a healthy interpreter.
+    # Recreating it kills detached Codex bridges sharing this venv and leaves
+    # every subscription model disconnected until bootstrap finishes. Verify
+    # version, provenance and stdlib first; the dependency stage still performs
+    # the locked sync and import checks. Broken/mismatched runtimes retain the
+    # transactional repair path below.
+    $existingVenvPath = Join-Path $InstallDir "venv"
+    if (Test-ReusableManagedVenv -VenvPath $existingVenvPath -BasePython $resolvedPython.Path -Version $resolvedPython.Version) {
+        $env:UV_PYTHON = Join-Path $existingVenvPath "Scripts\python.exe"
+        Write-Success "Reusing healthy managed virtual environment; running Codex bridges preserved"
+        return
+    }
+
     Write-Info "Creating virtual environment with Python $($resolvedPython.Version)..."
     
     Push-Location $InstallDir