diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 31023e4..aaa7056 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -57,13 +57,33 @@ jobs:
           path: coverage.xml
 
   # ---------------------------------------------------------------
-  # Job 2 — Build Docker images (only when Docker files change)
+  # Job 0 — Detect whether Docker-relevant files changed
+  # ---------------------------------------------------------------
+  changes:
+    runs-on: ubuntu-latest
+    outputs:
+      docker: ${{ steps.filter.outputs.docker }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dorny/paths-filter@v3
+        id: filter
+        with:
+          filters: |
+            docker:
+              - 'docker/**'
+              - 'pyproject.toml'
+              - 'uv.lock'
+              - 'requirements.txt'
+              - '.github/workflows/ci.yml'
+
+  # ---------------------------------------------------------------
+  # Job 2 — Build Docker images (only when Docker-relevant files change)
   # ---------------------------------------------------------------
   docker-build:
     runs-on: ubuntu-latest
-    needs: lint-and-test
+    needs: [lint-and-test, changes]
     if: >
-      github.event_name == 'pull_request' ||
+      needs.changes.outputs.docker == 'true' ||
       contains(github.event.head_commit.message, '[docker]')
 
     steps: