diff --git a/.gitea/workflows/ci.yaml b/.gitea/workflows/ci.yaml
index f9d22c1..3373cec 100644
--- a/.gitea/workflows/ci.yaml
+++ b/.gitea/workflows/ci.yaml
@@ -63,7 +63,8 @@ jobs:
     if: ${{ needs.changes.outputs.dockerfile == 'true' }}
     uses: ./.gitea/workflows/docker.yaml
     with:
-      push: ${{ github.event_name != 'pull_request' }}
+      # Explicit string, not a boolean expression (act_runner mangles bools).
+      push: ${{ github.event_name == 'pull_request' && 'false' || 'true' }}
 
   # Runs after docker (if docker ran). A skipped docker job is fine; a failed
   # one blocks this via !failure(). Re-run tests when code OR the image changed.
diff --git a/.gitea/workflows/docker.yaml b/.gitea/workflows/docker.yaml
index 699af5b..27fa328 100644
--- a/.gitea/workflows/docker.yaml
+++ b/.gitea/workflows/docker.yaml
@@ -4,19 +4,22 @@ name: '🐳 Builder Image'
 # It is called by ci.yaml only when Dockerfile.builder or docs/requirements.txt
 # change. It runs on the host runner (NOT inside the builder container) because
 # it needs the Docker CLI/daemon.
+# Note: `push` is a STRING ("true"/"false"), not a boolean. Gitea's act_runner
+# mangles boolean inputs passed from an expression (they arrive as false), so we
+# pass an explicit string and compare with == 'true' below.
 on:
   workflow_call:
     inputs:
       push:
-        description: 'Push the built image to the registry'
-        type: boolean
-        default: true
+        description: 'Push the built image to the registry ("true"/"false")'
+        type: string
+        default: 'true'
   workflow_dispatch:
     inputs:
       push:
-        description: 'Push the built image to the registry'
-        type: boolean
-        default: true
+        description: 'Push the built image to the registry ("true"/"false")'
+        type: string
+        default: 'true'
 
 jobs:
   build:
@@ -48,7 +51,7 @@ jobs:
             .
 
       - name: Push builder image
-        if: ${{ inputs.push }}
+        if: ${{ inputs.push == 'true' }}
         run: |
           docker push gitea.tourolle.paris/dtourolle/kpnpp-builder:latest
           docker push gitea.tourolle.paris/dtourolle/kpnpp-builder:${{ github.sha }}
diff --git a/Dockerfile.builder b/Dockerfile.builder
index 7ad29c6..749f5f1 100644
--- a/Dockerfile.builder
+++ b/Dockerfile.builder
@@ -1,4 +1,4 @@
-# KPN++ Builder Image  (CI: pipeline trigger)
+# KPN++ Builder Image  (CI: pipeline trigger v2)
 # Pre-built image with GCC, CMake, Ninja, and Python dev headers for building and testing KPN++
 # Build: docker build -f Dockerfile.builder -t gitea.tourolle.paris/dtourolle/kpnpp-builder:latest .
 # Push:  docker push gitea.tourolle.paris/dtourolle/kpnpp-builder:latest