diff --git a/gitea/actions/local-ci-build/action.yml b/gitea/actions/local-ci-build/action.yml
index 6f5f524..14693f3 100644
--- a/gitea/actions/local-ci-build/action.yml
+++ b/gitea/actions/local-ci-build/action.yml
@@ -189,7 +189,13 @@ runs:
         Set-StrictMode -Version Latest
         $ErrorActionPreference = 'Stop'
 
-        $ciScriptsDir = $env:GITEA_CI_SCRIPT_ROOT
+        # Resolve Python interpreter from venv (Phase A4 — Python orchestrator).
+        # Override with CI_VENV_PYTHON env var; default matches Setup-Host.ps1 layout.
+        $venvPython = $env:CI_VENV_PYTHON
+        if (-not $venvPython) { $venvPython = 'F:\CI\python\venv\Scripts\python.exe' }
+        if (-not (Test-Path -LiteralPath $venvPython)) {
+            throw "Python interpreter not found at '$venvPython'. Set CI_VENV_PYTHON or run Setup-Host.ps1."
+        }
 
         # Build job ID — append suffix when provided (matrix disambiguation)
         $jobId = '${{ github.run_id }}-${{ github.run_attempt }}'
@@ -212,15 +218,6 @@ runs:
             $repoUrl = '${{ github.server_url }}/${{ github.repository }}.git'
         }
 
-        # Parse extra-guest-env-json into a hashtable (§6.5 secret injection)
-        $extraGuestEnv = @{}
-        if ($env:INPUT_EXTRA_GUEST_ENV_JSON -and $env:INPUT_EXTRA_GUEST_ENV_JSON -ne '{}') {
-            $parsed = $env:INPUT_EXTRA_GUEST_ENV_JSON | ConvertFrom-Json
-            foreach ($prop in $parsed.PSObject.Properties) {
-                $extraGuestEnv[$prop.Name] = [string]$prop.Value
-            }
-        }
-
         # Resolve guest OS: honor explicit input; for Auto, infer from RUNNER_LABELS
         $resolvedGuestOS = $env:INPUT_GUEST_OS
         if ($resolvedGuestOS -eq 'Auto') {
@@ -252,27 +249,30 @@ runs:
             }
         }
 
-        # Build parameter hashtable for Invoke-CIJob.ps1
-        $params = @{
-            JobId               = $jobId
-            RepoUrl             = $repoUrl
-            Branch              = '${{ github.ref_name }}'
-            Commit              = '${{ github.sha }}'
-            BuildCommand        = $env:INPUT_BUILD_COMMAND
-            GuestArtifactSource = $env:INPUT_ARTIFACT_SOURCE
-            GuestOS             = $resolvedGuestOS
-            Configuration       = $env:INPUT_CONFIGURATION
+        # Build argument list for the Python CLI. Long-form kebab-case flags only.
+        $pyArgs = @(
+            '-m', 'ci_orchestrator', 'job',
+            '--job-id',                $jobId,
+            '--repo-url',              $repoUrl,
+            '--branch',                '${{ github.ref_name }}',
+            '--commit',                '${{ github.sha }}',
+            '--build-command',         $env:INPUT_BUILD_COMMAND,
+            '--guest-artifact-source', $env:INPUT_ARTIFACT_SOURCE,
+            '--guest-os',              $resolvedGuestOS,
+            '--configuration',         $env:INPUT_CONFIGURATION,
+            '--template-path',         $resolvedTemplatePath,
+            '--snapshot-name',         $resolvedSnapshotName
+        )
+
+        if ($env:INPUT_SUBMODULES       -eq 'true') { $pyArgs += '--submodules' }
+        if ($env:INPUT_USE_GIT_CLONE    -eq 'true') { $pyArgs += '--use-git-clone' }
+        if ($env:INPUT_USE_SHARED_CACHE -eq 'true') { $pyArgs += '--use-shared-cache' }
+        if ($env:INPUT_SKIP_ARTIFACT    -eq 'true') { $pyArgs += '--skip-artifact' }
+        if ($env:INPUT_EXTRA_GUEST_ENV_JSON -and $env:INPUT_EXTRA_GUEST_ENV_JSON -ne '{}') {
+            $pyArgs += @('--extra-env-json', $env:INPUT_EXTRA_GUEST_ENV_JSON)
         }
 
-        if ($env:INPUT_SUBMODULES       -eq 'true') { $params['Submodules']    = $true }
-        if ($env:INPUT_USE_GIT_CLONE    -eq 'true') { $params['UseGitClone']    = $true }
-        if ($env:INPUT_USE_SHARED_CACHE -eq 'true') { $params['UseSharedCache'] = $true }
-        if ($env:INPUT_SKIP_ARTIFACT    -eq 'true') { $params['SkipArtifact']   = $true }
-        if ($resolvedTemplatePath)                   { $params['TemplatePath']   = $resolvedTemplatePath }
-        if ($resolvedSnapshotName)                { $params['SnapshotName']  = $resolvedSnapshotName }
-        if ($extraGuestEnv.Count -gt 0)           { $params['ExtraGuestEnv'] = $extraGuestEnv }
-
-        & "$ciScriptsDir\Invoke-CIJob.ps1" @params
+        & $venvPython @pyArgs
         if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
 
         # Emit outputs consumed by subsequent steps
diff --git a/runner/config.yaml b/runner/config.yaml
index d5cd66e..c5a82ab 100644
--- a/runner/config.yaml
+++ b/runner/config.yaml
@@ -35,6 +35,9 @@ runner:
     GITEA_CI_SSH_KEY_PATH: "F:\\CI\\keys\\ci_linux"
     # Root directory of the local-ci-system repository on this host (scripts\ subdir)
     GITEA_CI_SCRIPT_ROOT: "N:\\Code\\Workspace\\Local-CI-CD-System\\scripts"
+    # Force UTF-8 stdio for the Python orchestrator (Phase A4) so non-ASCII
+    # characters in build logs survive the act_runner -> Gitea round-trip.
+    PYTHONIOENCODING: "utf-8"
 
   # Optional: load additional env vars from a file (one KEY=VALUE per line)
   # env_file: "F:\\CI\\runner.env"