Implement P05 checked services and safe selected delivery recovery

Assistant: codex
Assistant-Model: gpt-6-astra
Assistant-Session: 01a092fe-13b1-7f12-ac74-7d258af4d79c

.forgejo/workflows/acceptance.yaml

@@ -0,0 +1,21 @@
+name: Transactional mail acceptance
+on:
+  push:
+    branches: [main]
+    paths: ["src/**", "tests/**", "pyproject.toml", ".forgejo/workflows/acceptance.yaml"]
+  workflow_dispatch:
+jobs:
+  mail:
+    runs-on: ubuntu-latest
+    container:
+      image: python:3.12-slim@sha256:d764629ce0ddd8c71fd371e9901efb324a95789d2315a47db7e4d27e78f1b0e9
+    steps:
+      - name: Test exact source commit
+        run: |
+          set -eu
+          mkdir source
+          python -c 'import os, urllib.request; urllib.request.urlretrieve("https://forgejo.coulomb.social/" + os.environ["GITHUB_REPOSITORY"] + "/archive/" + os.environ["GITHUB_SHA"] + ".tar.gz", "source.tar.gz")'
+          tar xzf source.tar.gz -C source --strip-components=1
+          cd source
+          pip install . pytest
+          PYTHONDONTWRITEBYTECODE=1 PYTHONPATH=src python -m pytest -p no:cacheprovider -q