diff --git a/.github/scripts/ecosystem_smoke.jl b/.github/scripts/ecosystem_smoke.jl
new file mode 100644
index 0000000..d0c0c8b
--- /dev/null
+++ b/.github/scripts/ecosystem_smoke.jl
@@ -0,0 +1,39 @@
+using Pkg
+
+Pkg.develop(path = ENV["QI_PATH"])
+for path in readdir(ENV["DOWNSTREAMS_PATH"]; join = true)
+    Pkg.develop(path = path)
+end
+Pkg.add("TensorCore")
+
+modules = map((
+    :QuantumInterface,
+    :QuantumOpticsBase,
+    :QuantumOptics,
+    :SecondQuantizedAlgebra,
+    :Gabs,
+    :QuantumSymbolics,
+    :QuantumClifford,
+    :QuantumSavory,
+)) do name
+    Base.eval(Main, :(import $name))
+    getfield(Main, name)
+end
+import TensorCore
+
+for mod in modules
+    for name in (:tensor, :⊗)
+        isdefined(mod, name) || continue
+        @assert getfield(mod, name) === TensorCore.tensor "$mod.$name is not TensorCore.tensor"
+    end
+end
+@assert !applicable(TensorCore.tensor)
+
+ambiguities = Base.detect_ambiguities(modules..., TensorCore; recursive = true)
+tensor_ambiguities = filter(ambiguities) do (left, right)
+    any((left, right)) do method
+        isdefined(method.module, method.name) &&
+            getfield(method.module, method.name) === TensorCore.tensor
+    end
+end
+@assert isempty(tensor_ambiguities) "TensorCore.tensor ambiguities: $tensor_ambiguities"
diff --git a/.github/scripts/test_downstream.jl b/.github/scripts/test_downstream.jl
new file mode 100644
index 0000000..4ee13f5
--- /dev/null
+++ b/.github/scripts/test_downstream.jl
@@ -0,0 +1,11 @@
+using Pkg
+using TOML
+
+qi_path = ENV["QI_PATH"]
+downstream_path = ENV["DOWNSTREAM_PATH"]
+package = TOML.parsefile(joinpath(downstream_path, "Project.toml"))["name"]
+
+Pkg.develop(path = qi_path)
+Pkg.develop(path = downstream_path)
+Pkg.build(package)
+Pkg.test(package)
diff --git a/.github/workflows/breakage.yml b/.github/workflows/breakage.yml
index d95961e..c17343a 100644
--- a/.github/workflows/breakage.yml
+++ b/.github/workflows/breakage.yml
@@ -17,6 +17,8 @@ jobs:
         pkg: [
           "qojulia/QuantumOpticsBase.jl",
           "qojulia/QuantumOptics.jl",
+          "qojulia/SecondQuantizedAlgebra.jl",
+          "QuantumSavory/Gabs.jl",
           "QuantumSavory/QuantumSymbolics.jl",
           "QuantumSavory/QuantumClifford.jl",
           "QuantumSavory/QuantumSavory.jl",
@@ -41,30 +43,48 @@ jobs:
             ${{ runner.os }}-test-${{ env.cache-name }}-
             ${{ runner.os }}-test-
             ${{ runner.os }}-
-      - uses: julia-actions/julia-buildpkg@v1
-
       # Breakage test
       - name: 'Breakage of ${{ matrix.pkg }}, ${{ matrix.pkgversion }} version'
         env:
           URL: ${{ matrix.pkg }}
           VERSION: ${{ matrix.pkgversion }}
         run: |
-          set -v
-          mkdir -p ./pr
-          echo "${{ github.event.number }}" > ./pr/NR
-          git clone https://github.com/$URL
-          export PKG=$(echo $URL | cut -f2 -d/)
-          cd $PKG
-          TAG=$VERSION
-          export TAG
-          julia -e 'using Pkg;
-            PKG, TAG, VERSION = ENV["PKG"], ENV["TAG"], ENV["VERSION"]
-            joburl = joinpath(ENV["GITHUB_SERVER_URL"], ENV["GITHUB_REPOSITORY"], "actions/runs", ENV["GITHUB_RUN_ID"])
-            open("../pr/$PKG-$VERSION", "w") do io
-                TAG == "no_tag" && error("No tag for $VERSION")
-                pkg"activate .";
-                pkg"instantiate";
-                pkg"dev ../";
-                pkg"build";
-                pkg"test";
-            end'
+          downstream="${RUNNER_TEMP}/downstream"
+          environment="${RUNNER_TEMP}/environment"
+          git clone "https://github.com/${URL}" "$downstream"
+          mkdir -p "$environment"
+          QI_PATH="$GITHUB_WORKSPACE" DOWNSTREAM_PATH="$downstream" \
+            julia --project="$environment" .github/scripts/test_downstream.jl
+
+  ecosystem-smoke:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: julia-actions/setup-julia@v3
+        with:
+          version: 1
+          arch: x64
+      - uses: actions/cache@v5
+        env:
+          cache-name: cache-artifacts
+        with:
+          path: ~/.julia/artifacts
+          key: ${{ runner.os }}-smoke-${{ env.cache-name }}-${{ hashFiles('**/Project.toml') }}
+          restore-keys: |
+            ${{ runner.os }}-smoke-${{ env.cache-name }}-
+            ${{ runner.os }}-smoke-
+            ${{ runner.os }}-
+      - name: Check the shared tensor interface
+        run: |
+          downstreams="${RUNNER_TEMP}/downstreams"
+          environment="${RUNNER_TEMP}/environment"
+          mkdir -p "$downstreams" "$environment"
+          git clone https://github.com/qojulia/QuantumOpticsBase.jl "$downstreams/QuantumOpticsBase"
+          git clone https://github.com/qojulia/QuantumOptics.jl "$downstreams/QuantumOptics"
+          git clone https://github.com/qojulia/SecondQuantizedAlgebra.jl "$downstreams/SecondQuantizedAlgebra"
+          git clone https://github.com/QuantumSavory/Gabs.jl "$downstreams/Gabs"
+          git clone https://github.com/QuantumSavory/QuantumSymbolics.jl "$downstreams/QuantumSymbolics"
+          git clone https://github.com/QuantumSavory/QuantumClifford.jl "$downstreams/QuantumClifford"
+          git clone https://github.com/QuantumSavory/QuantumSavory.jl "$downstreams/QuantumSavory"
+          QI_PATH="$GITHUB_WORKSPACE" DOWNSTREAMS_PATH="$downstreams" \
+            julia --project="$environment" .github/scripts/ecosystem_smoke.jl