fix(server): block V2 replacements until session cleanup completes

.github/workflows/ci.yml

@@ -5,6 +5,8 @@ on:
   push:
     branches:
       - main
+      # Keep v2 checked while its pull request has conflicts with main.
+      - t3code/codex-turn-mapping
 
 permissions:
   contents: read
@@ -52,7 +54,9 @@ jobs:
         run: vpr typecheck
 
       - name: Install browser secret helper build libraries
-        run: sudo apt-get update && sudo apt-get install -y libsecret-1-dev pkg-config
+        run: |
+          sudo sed -i 's|http://|https://|g' /etc/apt/blacksmith-ubuntu-mirrors.txt /etc/apt/sources.list.d/ubuntu.sources
+          sudo apt-get update && sudo apt-get install -y libsecret-1-dev pkg-config
 
       - name: Build desktop pipeline
         run: vp run build:desktop
@@ -78,6 +82,17 @@ jobs:
             !/.repos/
           sparse-checkout-cone-mode: false
 
+      # Blacksmith boots GitHub's Ubuntu runner image (gcc is usually present),
+      # but ACP process-tree live tests compile a small pthread fixture with `cc`
+      # and soft-skip when it is missing. Install build-essential so that path
+      # always runs in CI instead of silently no-oping.
+      - name: Install C toolchain for process-tree fixtures
+        run: |
+          sudo sed -i 's|http://|https://|g' /etc/apt/blacksmith-ubuntu-mirrors.txt /etc/apt/sources.list.d/ubuntu.sources
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends build-essential
+          command -v cc
+
       - name: Setup Vite+
         uses: voidzero-dev/setup-vp@v1
         with: