fix private pip installation and notification of healed build

.gitea/workflows/python-checks.yml

@@ -22,8 +22,10 @@ on:
         type: boolean
         default: true
       use_private_index:
-        type: boolean
-        default: false
+        # Gitea 1.27.x does not reliably propagate boolean inputs through
+        # reusable workflows.  Keep this a string until that regression is fixed.
+        type: string
+        default: "false"
 
 jobs:
   check:
@@ -38,15 +40,54 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Configure private package index
-        if: ${{ inputs.use_private_index }}
+      # Keep this step unconditional.  A Gitea Actions update can otherwise silently
+      # skip it when a boolean workflow_call input is not propagated as expected;
+      # pip then misleadingly reports that the private package does not exist.
+      - name: Configure and verify private package index
         env:
+          PRIVATE_INDEX_ENABLED: ${{ inputs.use_private_index }}
           PRIVATE_INDEX_URL: ${{ secrets.PIP_EXTRA_INDEX_URL }}
         run: |
+          echo "Private package index requested: ${PRIVATE_INDEX_ENABLED:-<empty>}"
+          if [ "${PRIVATE_INDEX_ENABLED}" != "true" ]; then
+            echo "Private package index is not requested for this workflow call."
+            exit 0
+          fi
           if [ -z "$PRIVATE_INDEX_URL" ]; then
             echo "use_private_index=true but the PIP_EXTRA_INDEX_URL secret is empty or not set"
             exit 1
           fi
+
+          # Probe the configured simple index before pip resolves dependencies.  The
+          # probe deliberately prints only scheme/host/path, never URL credentials.
+          python - "$PRIVATE_INDEX_URL" <<'PY'
+          import base64
+          import sys
+          from urllib.error import HTTPError, URLError
+          from urllib.parse import unquote, urlsplit, urlunsplit
+          from urllib.request import Request, urlopen
+
+          configured_url = sys.argv[1]
+          parsed = urlsplit(configured_url)
+          hostname = parsed.hostname or "<missing host>"
+          port = f":{parsed.port}" if parsed.port else ""
+          safe_url = urlunsplit((parsed.scheme, f"{hostname}{port}", parsed.path, parsed.query, ""))
+          request = Request(safe_url, headers={"Accept": "application/vnd.pypi.simple.v1+json"})
+          if parsed.username is not None:
+              credentials = f"{unquote(parsed.username)}:{unquote(parsed.password or '')}".encode()
+              request.add_header("Authorization", "Basic " + base64.b64encode(credentials).decode())
+          try:
+              with urlopen(request, timeout=15) as response:  # nosec B310 -- configured CI package index
+                  print(f"Private package-index probe: HTTP {response.status} at {safe_url}")
+          except HTTPError as error:
+              print(f"Private package-index probe: HTTP {error.code} at {safe_url}")
+              if error.code in {401, 403}:
+                  print("Authentication was rejected by the private package index.")
+              raise SystemExit(1)
+          except URLError as error:
+              print(f"Private package-index probe could not reach {safe_url}: {error.reason}")
+              raise SystemExit(1)
+          PY
           pip config --site set global.extra-index-url "$PRIVATE_INDEX_URL"
 
       - name: Install Tools & Deps
@@ -86,4 +127,4 @@ jobs:
         with:
           name: coverage-xml
           path: coverage.xml
-          if-no-files-found: warn
+          if-no-files-found: warn