diff --git a/.github/workflows/studio-windows-api-smoke.yml b/.github/workflows/studio-windows-api-smoke.yml
index b1d6a31b1e..7c10183f35 100644
--- a/.github/workflows/studio-windows-api-smoke.yml
+++ b/.github/workflows/studio-windows-api-smoke.yml
@@ -84,7 +84,11 @@ jobs:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           New-Item -ItemType Directory -Force -Path logs | Out-Null
-          & ./install.ps1 --local --no-torch 2>&1 | Tee-Object -FilePath logs/install.log
+          # *>&1 captures Write-Host (Information stream) output;
+          # plain 2>&1 does not. setup.ps1 emits "prebuilt installed
+          # and validated" via Write-Host, and we grep for that.
+          $ProgressPreference = 'SilentlyContinue'
+          & ./install.ps1 --local --no-torch *>&1 | Tee-Object -FilePath logs/install.log
 
       - name: Assert install.ps1 used the Windows llama.cpp prebuilt
         run: |
diff --git a/.github/workflows/studio-windows-inference-smoke.yml b/.github/workflows/studio-windows-inference-smoke.yml
index e387e8326f..3a11e494cb 100644
--- a/.github/workflows/studio-windows-inference-smoke.yml
+++ b/.github/workflows/studio-windows-inference-smoke.yml
@@ -94,7 +94,11 @@ jobs:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           New-Item -ItemType Directory -Force -Path logs | Out-Null
-          & ./install.ps1 --local --no-torch 2>&1 | Tee-Object -FilePath logs/install.log
+          # *>&1 captures Write-Host (Information stream) output;
+          # plain 2>&1 does not. setup.ps1 emits "prebuilt installed
+          # and validated" via Write-Host, and we grep for that.
+          $ProgressPreference = 'SilentlyContinue'
+          & ./install.ps1 --local --no-torch *>&1 | Tee-Object -FilePath logs/install.log
 
       - name: Assert install.ps1 used the Windows llama.cpp prebuilt
         run: |
@@ -329,7 +333,11 @@ jobs:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           New-Item -ItemType Directory -Force -Path logs | Out-Null
-          & ./install.ps1 --local --no-torch 2>&1 | Tee-Object -FilePath logs/install.log
+          # *>&1 captures Write-Host (Information stream) output;
+          # plain 2>&1 does not. setup.ps1 emits "prebuilt installed
+          # and validated" via Write-Host, and we grep for that.
+          $ProgressPreference = 'SilentlyContinue'
+          & ./install.ps1 --local --no-torch *>&1 | Tee-Object -FilePath logs/install.log
 
       - name: Assert install.ps1 used the Windows llama.cpp prebuilt
         run: |
@@ -655,7 +663,11 @@ jobs:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           New-Item -ItemType Directory -Force -Path logs | Out-Null
-          & ./install.ps1 --local --no-torch 2>&1 | Tee-Object -FilePath logs/install.log
+          # *>&1 captures Write-Host (Information stream) output;
+          # plain 2>&1 does not. setup.ps1 emits "prebuilt installed
+          # and validated" via Write-Host, and we grep for that.
+          $ProgressPreference = 'SilentlyContinue'
+          & ./install.ps1 --local --no-torch *>&1 | Tee-Object -FilePath logs/install.log
 
       - name: Assert install.ps1 used the Windows llama.cpp prebuilt
         run: |
diff --git a/.github/workflows/studio-windows-ui-smoke.yml b/.github/workflows/studio-windows-ui-smoke.yml
index a96b54d28a..843caf71a6 100644
--- a/.github/workflows/studio-windows-ui-smoke.yml
+++ b/.github/workflows/studio-windows-ui-smoke.yml
@@ -97,7 +97,16 @@ jobs:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           New-Item -ItemType Directory -Force -Path logs | Out-Null
-          & ./install.ps1 --local --no-torch 2>&1 | Tee-Object -FilePath logs/install.log
+          # *>&1 redirects ALL PowerShell streams (stdout, stderr,
+          # warning, verbose, debug, information) into the success
+          # stream so Tee-Object captures everything. install.ps1
+          # and setup.ps1 emit step/substep markers via Write-Host
+          # which lands on the Information stream (PS 5+); without
+          # the wildcard redirect, those markers (including
+          # "prebuilt installed and validated") never reach
+          # logs/install.log and the post-step grep asserter fails.
+          $ProgressPreference = 'SilentlyContinue'
+          & ./install.ps1 --local --no-torch *>&1 | Tee-Object -FilePath logs/install.log
 
       - name: Assert install.ps1 used the Windows llama.cpp prebuilt
         run: |
diff --git a/.github/workflows/studio-windows-update-smoke.yml b/.github/workflows/studio-windows-update-smoke.yml
index 551760825a..9b11ab50a3 100644
--- a/.github/workflows/studio-windows-update-smoke.yml
+++ b/.github/workflows/studio-windows-update-smoke.yml
@@ -79,7 +79,11 @@ jobs:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           New-Item -ItemType Directory -Force -Path logs | Out-Null
-          & ./install.ps1 --local --no-torch 2>&1 | Tee-Object -FilePath logs/install.log
+          # *>&1 captures Write-Host (Information stream) output;
+          # plain 2>&1 does not. setup.ps1 emits "prebuilt installed
+          # and validated" via Write-Host, and we grep for that.
+          $ProgressPreference = 'SilentlyContinue'
+          & ./install.ps1 --local --no-torch *>&1 | Tee-Object -FilePath logs/install.log
 
       - name: Assert install.ps1 used the Windows llama.cpp prebuilt
         run: |