diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 5990d9c..1f79aa0 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -1,11 +1,14 @@
-# To get started with Dependabot version updates, you'll need to specify which
-# package ecosystems to update and where the package manifests are located.
-# Please see the documentation for all configuration options:
-# https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
-
+# The previous file was GitHub's unfilled template (package-ecosystem: ""), which
+# does nothing. Weekly PRs for the pinned things that otherwise go stale.
 version: 2
 updates:
-  - package-ecosystem: "" # See documentation for possible values
-    directory: "/" # Location of package manifests
+  # SHA-pinned actions: Dependabot bumps the SHA and the "# vX.Y.Z" comment together.
+  - package-ecosystem: "github-actions"
+    directory: "/"
     schedule:
       interval: "weekly"
+  # maturin (hash-pinned). Verify the first PR keeps the --hash lines intact.
+  - package-ecosystem: "pip"
+    directory: "/environments/alpine-3.24-musl"
+    schedule:
+      interval: "weekly"
\ No newline at end of file
diff --git a/.github/workflows/build-environment-image.yml b/.github/workflows/build-environment-image.yml
index 1112a4e..0c91cb9 100644
--- a/.github/workflows/build-environment-image.yml
+++ b/.github/workflows/build-environment-image.yml
@@ -133,6 +133,12 @@ jobs:
             aarch64) goarch=arm64; rustup_sha_var=RUSTUP_SHA256_AARCH64 ;;
             *) echo "::error::unknown arch $ARCH"; exit 1 ;;
           esac
+          # The runner image is a declared trust root (not pinned): record exactly what ran.
+          [ -n "${ImageOS:-}" ] && [ -n "${ImageVersion:-}" ] \
+            || { echo "::error::ImageOS/ImageVersion not set; not a GitHub-hosted runner?"; exit 1; }
+          docker_version="$(docker version --format '{{.Server.Version}}')"
+          buildx_version="$(docker buildx version | awk '{print $2}')"
+          [ -n "$docker_version" ] && [ -n "$buildx_version" ] || { echo "::error::cannot read docker/buildx versions"; exit 1; }
           arg() { sed -n "s/^ARG $1=//p" "$CONTEXT/Containerfile"; }
           base="$(awk '/^FROM /{print $2; exit}' "$CONTEXT/Containerfile")"
           base_ref="${base%@*}"
@@ -153,6 +159,11 @@ jobs:
             --arg assert_script_sha256 "$(sha256sum "$CONTEXT/assert-sccache-build.sh" | cut -d' ' -f1)" \
             --arg requirements_sha256 "$(sha256sum "$CONTEXT/requirements-builder.txt" | cut -d' ' -f1)" \
             --arg apk_lock_sha256 "$(sha256sum "$CONTEXT/apk.lock.$ARCH" | cut -d' ' -f1)" \
+            --arg runner_image_os "$ImageOS" \
+            --arg runner_image_version "$ImageVersion" \
+            --arg runner_arch "${RUNNER_ARCH:-}" \
+            --arg docker_version "$docker_version" \
+            --arg buildx_version "$buildx_version" \
             --arg builder_image "$IMAGE@$DIGEST" \
             --arg commit "$COMMIT" \
             '{base_image_ref:$base_ref, base_image_index_digest:$base_index, base_platform:$base_platform,
@@ -160,6 +171,8 @@ jobs:
               rustup_sha256:$rustup_sha256, rust_version:$rust_version, sccache_version:$sccache_version,
               cargo_auditable_version:$cargo_auditable_version, assert_script_sha256:$assert_script_sha256,
               requirements_builder_sha256:$requirements_sha256, apk_lock_sha256:$apk_lock_sha256,
+              runner:{image_os:$runner_image_os, image_version:$runner_image_version, arch:$runner_arch,
+                      docker_version:$docker_version, buildx_version:$buildx_version},
               builder_image:$builder_image, source_commit:$commit}' > "builder-inputs.$ARCH.json"
           cat "builder-inputs.$ARCH.json"
 
diff --git a/.github/workflows/merge-bot.yml b/.github/workflows/merge-bot.yml
index 0ec18aa..a770d9a 100644
--- a/.github/workflows/merge-bot.yml
+++ b/.github/workflows/merge-bot.yml
@@ -136,20 +136,27 @@ jobs:
       - name: Wait for CodeQL checks
         run: |
           set -euo pipefail
+          # Required checks must exist, be completed, and conclude success.
+          # none/null (not created or still running) and neutral (CodeQL's
+          # aggregate check reports neutral while results are still being
+          # processed) mean "not settled yet": retry. Anything else that is
+          # not success is a hard fail. Timeout fails closed.
           for i in $(seq 1 20); do
             ok=1
-            for name in "CodeQL" "Analyze (actions)"; do
+            for name in "CodeQL" "Analyze (actions)" "Analyze (python)"; do
               c=$(gh api "repos/$GITHUB_REPOSITORY/commits/$HEAD_SHA/check-runs?per_page=100" \
-                --jq "[.check_runs[] | select(.name == \"$name\")] | sort_by(.started_at) | last | .conclusion // \"none\"")
-              echo "$name: $c"
-              if [ "$c" = "none" ] || [ "$c" = "null" ]; then ok=0
-              elif [ "$c" != "success" ]; then echo "::error::$name concluded $c"; exit 1
-              fi
+                --jq "[.check_runs[] | select(.name == \"$name\")] | sort_by(.started_at) | last | if . == null or .status != \"completed\" then \"none\" else .conclusion // \"none\" end")
+              echo "attempt $i: $name: $c"
+              case "$c" in
+                success) ;;
+                none|null|neutral) ok=0 ;;
+                *) echo "::error::$name concluded $c"; exit 1 ;;
+              esac
             done
             [ "$ok" = 1 ] && { echo "CodeQL checks green."; exit 0; }
             sleep 30
           done
-          echo "::error::CodeQL produced no result in 10 min. Check that the CodeQL workflow is enabled."; exit 1
+          echo "::error::CodeQL checks did not all reach success in 10 min (last state above). Check that the CodeQL workflow is enabled."; exit 1
 
   # ===============================================================
   # JOB 3: Human approval gate, then fast-forward push via GitHub App
@@ -191,4 +198,4 @@ jobs:
           # Non-force ref update: rejected unless it is a pure fast-forward. Same SHA, signatures kept.
           gh api -X PATCH "repos/$GITHUB_REPOSITORY/git/refs/heads/$BASE_REF" \
             -f sha="$HEAD_SHA" -F force=false --jq '.object.sha'
-          echo "Fast-forwarded $BASE_REF to $HEAD_SHA."
+          echo "Fast-forwarded $BASE_REF to $HEAD_SHA."
\ No newline at end of file