diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8dd3596..19ef10b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -270,9 +270,38 @@ jobs:
       - uses: actions/setup-go@v7
         with:
           go-version: 1.27.2
-      - run: sudo apt-get update && sudo apt-get install -y qemu-user-static
+      # ⛔ `qemu-user-static` is a VIRTUAL package on Ubuntu 26.04, which
+      # `ubuntu-latest` became on 2026-10-19, and apt refuses to choose between its
+      # two providers:
+      #
+      #   E: Package 'qemu-user-static' has no installation candidate
+      #
+      # ⚠ Installing a provider is NOT the fix: `qemu-user-binfmt` registers binfmt
+      # handlers, it does not ship the `qemu-<arch>-static` binaries this lane
+      # invokes. `qemu-user` ships the dynamic `qemu-<arch>`, which is all that
+      # `go test -exec` needs, so both are installed and BOTH NAMES are accepted
+      # below. go-tex/engine#645 has the full account.
+      - name: install qemu user-mode emulators
+        timeout-minutes: 10
+        run: sudo apt-get update && sudo apt-get install -y qemu-user qemu-user-binfmt
       - name: Test under qemu (${{ matrix.goarch }})
-        run: CGO_ENABLED=0 GOARCH=${{ matrix.goarch }} go test -exec=${{ matrix.qemu }} ./...
+        run: |
+          base="${{ matrix.qemu }}"
+          q=""
+          for cand in "$base" "${base%-static}"; do
+            command -v "$cand" >/dev/null 2>&1 && q="$cand" && break
+          done
+          # ⛔ A missing emulator FAILS this lane. A lane that reports success for
+          # an architecture it never ran is the one outcome this matrix exists to
+          # rule out.
+          if [ -z "$q" ]; then
+            echo "::error::no qemu user emulator for ${{ matrix.goarch }} (looked for $base and ${base%-static})"
+            exit 1
+          fi
+          # Printed on purpose: without it, "ran under emulation" and "skipped" are
+          # indistinguishable from a green tick.
+          echo "running ${{ matrix.goarch }} under $q"
+          CGO_ENABLED=0 GOARCH=${{ matrix.goarch }} go test -exec="$q" ./...
 
   # Live X11 proof: open a real window under Xvfb, present a known test
   # pattern, capture it and assert sampled pixels; synthesise a key + click