diff --git a/.github/workflows/nix-action-coq-8.20.yml b/.github/workflows/nix-action-coq-8.20.yml
index 8ff06daeb..99355a856 100644
--- a/.github/workflows/nix-action-coq-8.20.yml
+++ b/.github/workflows/nix-action-coq-8.20.yml
@@ -29,7 +29,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -94,7 +94,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -149,7 +149,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -197,7 +197,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -216,6 +216,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: Building/fetching current CI target
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
@@ -252,7 +256,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -325,7 +329,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -382,7 +386,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -441,7 +445,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -520,7 +524,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -539,6 +543,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
@@ -603,7 +611,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -622,6 +630,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
@@ -671,7 +683,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -742,7 +754,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -807,7 +819,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -869,7 +881,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -888,6 +900,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
@@ -948,7 +964,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1015,7 +1031,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1084,7 +1100,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1103,6 +1119,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
@@ -1158,7 +1178,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1177,6 +1197,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
@@ -1219,7 +1243,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1281,7 +1305,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1359,7 +1383,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1421,7 +1445,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1485,7 +1509,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1504,6 +1528,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
@@ -1554,7 +1582,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1573,6 +1601,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: hierarchy-builder'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-8.20"
@@ -1615,7 +1647,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1694,7 +1726,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1775,7 +1807,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
diff --git a/.github/workflows/nix-action-coq-master-min-elpi.yml b/.github/workflows/nix-action-coq-master-min-elpi.yml
index cd3387b1e..32dadea79 100644
--- a/.github/workflows/nix-action-coq-master-min-elpi.yml
+++ b/.github/workflows/nix-action-coq-master-min-elpi.yml
@@ -27,7 +27,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -75,7 +75,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -94,6 +94,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: Building/fetching current CI target
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
@@ -128,7 +132,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -191,7 +195,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -210,6 +214,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
@@ -274,7 +282,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -293,6 +301,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
@@ -342,7 +354,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -413,7 +425,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -478,7 +490,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -540,7 +552,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -559,6 +571,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
@@ -619,7 +635,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -686,7 +702,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -755,7 +771,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -774,6 +790,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
@@ -829,7 +849,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -848,6 +868,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
@@ -890,7 +914,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -952,7 +976,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1030,7 +1054,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1092,7 +1116,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1156,7 +1180,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1175,6 +1199,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
@@ -1225,7 +1253,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1244,6 +1272,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: hierarchy-builder'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master-min-elpi"
@@ -1286,7 +1318,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1365,7 +1397,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
diff --git a/.github/workflows/nix-action-coq-master.yml b/.github/workflows/nix-action-coq-master.yml
index 932525614..b3833600e 100644
--- a/.github/workflows/nix-action-coq-master.yml
+++ b/.github/workflows/nix-action-coq-master.yml
@@ -27,7 +27,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -75,7 +75,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -94,6 +94,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: Building/fetching current CI target
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
@@ -128,7 +132,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -191,7 +195,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -210,6 +214,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
@@ -274,7 +282,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -293,6 +301,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
@@ -342,7 +354,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -413,7 +425,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -478,7 +490,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -540,7 +552,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -559,6 +571,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
@@ -619,7 +635,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -686,7 +702,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -755,7 +771,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -774,6 +790,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
@@ -829,7 +849,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -848,6 +868,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
@@ -890,7 +914,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -952,7 +976,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1030,7 +1054,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1092,7 +1116,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1156,7 +1180,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1175,6 +1199,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: mathcomp-ssreflect'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
@@ -1225,7 +1253,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1244,6 +1272,10 @@ jobs:
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
         --argstr job "coq"
+    - if: steps.stepCheck.outputs.status == 'built'
+      name: 'Building/fetching previous CI target: stdlib'
+      run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
+        --argstr job "stdlib"
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: hierarchy-builder'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "coq-master"
@@ -1286,7 +1318,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
@@ -1365,7 +1397,7 @@ jobs:
         fetch-depth: 0
         ref: ${{ env.tested_commit }}
     - name: Cachix install
-      uses: cachix/install-nix-action@v27
+      uses: cachix/install-nix-action@v30
       with:
         nix_path: nixpkgs=channel:nixpkgs-unstable
     - name: Cachix setup coq-elpi
diff --git a/.nix/config.nix b/.nix/config.nix
index 3958ebf7f..ba91607c6 100644
--- a/.nix/config.nix
+++ b/.nix/config.nix
@@ -31,6 +31,7 @@ let master = [
       coqPackages = common-bundles // {
         coq.override.version = "8.20";
       };
+      # only way to override elpi version is in .nix/coq-overlays/coq-elpi/default.nix
     };
 
     "coq-master" = {
@@ -39,7 +40,7 @@ let master = [
         coqeal.job = false;  # broken in master, c.f. https://github.com/coq/coq/pull/19228
       };
       ocamlPackages = {
-        elpi.override.version = "v2.0.3";
+        elpi.override.version = "2.0.6";
       };
     };
       
@@ -51,7 +52,7 @@ let master = [
       ocamlPackages = {
         # when updating this, don't forget to update dune-project
         # then use it to regenerate coq-elpi.opam
-        elpi.override.version = "v2.0.3";
+        elpi.override.version = "2.0.6";
       };
     };
 
diff --git a/.nix/coq-nix-toolbox.nix b/.nix/coq-nix-toolbox.nix
index 76a268d4a..6ac626e65 100644
--- a/.nix/coq-nix-toolbox.nix
+++ b/.nix/coq-nix-toolbox.nix
@@ -1 +1 @@
-"858ff8dd010deded3b9cab8e04fbfad20151af5c"
+"76c44f0123e79740391775e2f977622e2bdc7f26"
diff --git a/.nix/coq-overlays/coq-elpi/default.nix b/.nix/coq-overlays/coq-elpi/default.nix
index 1d3dc1828..c3223b681 100644
--- a/.nix/coq-overlays/coq-elpi/default.nix
+++ b/.nix/coq-overlays/coq-elpi/default.nix
@@ -1,60 +1,151 @@
-{ lib, mkCoqDerivation, which, coq, version ? null }:
+{
+  lib,
+  mkCoqDerivation,
+  which,
+  coq,
+  stdlib,
+  version ? null,
+}:
 
 let
-  elpi = coq.ocamlPackages.elpi.override (lib.switch coq.coq-version [
-    { case = "8.11"; out = { version = "1.11.4"; };}
-    { case = "8.12"; out = { version = "1.12.0"; };}
-    { case = "8.13"; out = { version = "1.13.7"; };}
-    { case = "8.14"; out = { version = "1.13.7"; };}
-    { case = "8.15"; out = { version = "1.15.0"; };}
-    { case = "8.16"; out = { version = "1.17.0"; };}
-    { case = "8.17"; out = { version = "1.17.0"; };}
-    { case = "8.18"; out = { version = "1.18.1"; };}
-    { case = "8.20"; out = { version = "2.0.3"; };}
-  ] {} );
-in (mkCoqDerivation {
+  elpi = coq.ocamlPackages.elpi.override (
+    lib.switch coq.coq-version [
+      {
+        case = "8.11";
+        out = {
+          version = "1.11.4";
+        };
+      }
+      {
+        case = "8.12";
+        out = {
+          version = "1.12.0";
+        };
+      }
+      {
+        case = "8.13";
+        out = {
+          version = "1.13.7";
+        };
+      }
+      {
+        case = "8.14";
+        out = {
+          version = "1.13.7";
+        };
+      }
+      {
+        case = "8.15";
+        out = {
+          version = "1.15.0";
+        };
+      }
+      {
+        case = "8.16";
+        out = {
+          version = "1.17.0";
+        };
+      }
+      {
+        case = "8.17";
+        out = {
+          version = "1.17.0";
+        };
+      }
+      {
+        case = "8.18";
+        out = {
+          version = "1.18.1";
+        };
+      }
+      {
+        case = "8.19";
+        out = {
+          version = "1.18.1";
+        };
+      }
+      {
+        case = "8.20";
+        out = {
+          version = "2.0.6";
+        };
+      }
+    ] { }
+  );
+in
+(mkCoqDerivation {
   pname = "elpi";
-  repo  = "coq-elpi";
+  repo = "coq-elpi";
   owner = "LPCIC";
   inherit version;
   defaultVersion = lib.switch coq.coq-version [
-    { case = "8.20"; out = "2.2.0"; }
-    { case = "8.19"; out = "2.0.1"; }
-    { case = "8.18"; out = "2.0.0"; }
-    { case = "8.17"; out = "1.18.0"; }
-    { case = "8.16"; out = "1.15.6"; }
-    { case = "8.15"; out = "1.14.0"; }
-    { case = "8.14"; out = "1.11.2"; }
-    { case = "8.13"; out = "1.11.1"; }
-    { case = "8.12"; out = "1.8.3_8.12"; }
-    { case = "8.11"; out = "1.6.3_8.11"; }
+    {
+      case = "8.20";
+      out = "2.2.0";
+    }
+    {
+      case = "8.19";
+      out = "2.0.1";
+    }
+    {
+      case = "8.18";
+      out = "2.0.0";
+    }
+    {
+      case = "8.17";
+      out = "1.18.0";
+    }
+    {
+      case = "8.16";
+      out = "1.15.6";
+    }
+    {
+      case = "8.15";
+      out = "1.14.0";
+    }
+    {
+      case = "8.14";
+      out = "1.11.2";
+    }
+    {
+      case = "8.13";
+      out = "1.11.1";
+    }
+    {
+      case = "8.12";
+      out = "1.8.3_8.12";
+    }
+    {
+      case = "8.11";
+      out = "1.6.3_8.11";
+    }
   ] null;
-  release."2.2.0".sha256      = "sha256-rADEoqTXM7/TyYkUKsmCFfj6fjpWdnZEOK++5oLfC/I=";
-  release."2.0.1".sha256      = "sha256-cuoPsEJ+JRLVc9Golt2rJj4P7lKltTrrmQijjoViooc=";
-  release."2.0.0".sha256      = "sha256-A/cH324M21k3SZ7+YWXtaYEbu6dZQq3K0cb1RMKjbsM=";
-  release."1.19.0".sha256     = "sha256-kGoo61nJxeG/BqV+iQaV3iinwPStND+7+fYMxFkiKrQ=";
-  release."1.18.0".sha256     = "sha256-2fCOlhqi4YkiL5n8SYHuc3pLH+DArf9zuMH7IhpBc2Y=";
-  release."1.17.0".sha256     = "sha256-J8GatRKFU0ekNCG3V5dBI+FXypeHcLgC5QJYGYzFiEM=";
-  release."1.15.6".sha256     = "sha256-qc0q01tW8NVm83801HHOBHe/7H1/F2WGDbKO6nCXfno=";
-  release."1.15.1".sha256     = "sha256-NT2RlcIsFB9AvBhMxil4ZZIgx+KusMqDflj2HgQxsZg=";
-  release."1.14.0".sha256     = "sha256:1v2p5dlpviwzky2i14cj7gcgf8cr0j54bdm9fl5iz1ckx60j6nvp";
-  release."1.13.0".sha256     = "1j7s7dlnjbw222gnbrsjgmjck1yrx7h6hwm8zikcyxi0zys17w7n";
-  release."1.12.1".sha256     = "sha256-4mO6/co7NcIQSGIQJyoO8lNWXr6dqz+bIYPO/G0cPkY=";
-  release."1.11.2".sha256     = "0qk5cfh15y2zrja7267629dybd3irvxk1raz7z8qfir25a81ckd4";
-  release."1.11.1".sha256     = "10j076vc2hdcbm15m6s7b6xdzibgfcbzlkgjnlkr2vv9k13qf8kc";
-  release."1.10.1".sha256     = "1zsyx26dvj7pznfd2msl2w7zbw51q1nsdw0bdvdha6dga7ijf7xk";
-  release."1.9.7".sha256      = "0rvn12h9dpk9s4pxy32p8j0a1h7ib7kg98iv1cbrdg25y5vs85n1";
-  release."1.9.5".sha256      = "0gjdwmb6bvb5gh0a6ra48bz5fb3pr5kpxijb7a8mfydvar5i9qr6";
-  release."1.9.4".sha256      = "0nii7238mya74f9g6147qmpg6gv6ic9b54x5v85nb6q60d9jh0jq";
-  release."1.9.3".sha256      = "198irm800fx3n8n56vx1c6f626cizp1d7jfkrc6ba4iqhb62ma0z";
-  release."1.9.2".sha256      = "1rr2fr8vjkc0is7vh1461aidz2iwkigdkp6bqss4hhv0c3ijnn07";
-  release."1.8.3_8.12".sha256  = "15z2l4zy0qpw0ws7bvsmpmyv543aqghrfnl48nlwzn9q0v89p557";
+  release."2.2.0".sha256 = "sha256-rADEoqTXM7/TyYkUKsmCFfj6fjpWdnZEOK++5oLfC/I=";
+  release."2.0.1".sha256 = "sha256-cuoPsEJ+JRLVc9Golt2rJj4P7lKltTrrmQijjoViooc=";
+  release."2.0.0".sha256 = "sha256-A/cH324M21k3SZ7+YWXtaYEbu6dZQq3K0cb1RMKjbsM=";
+  release."1.19.0".sha256 = "sha256-kGoo61nJxeG/BqV+iQaV3iinwPStND+7+fYMxFkiKrQ=";
+  release."1.18.0".sha256 = "sha256-2fCOlhqi4YkiL5n8SYHuc3pLH+DArf9zuMH7IhpBc2Y=";
+  release."1.17.0".sha256 = "sha256-J8GatRKFU0ekNCG3V5dBI+FXypeHcLgC5QJYGYzFiEM=";
+  release."1.15.6".sha256 = "sha256-qc0q01tW8NVm83801HHOBHe/7H1/F2WGDbKO6nCXfno=";
+  release."1.15.1".sha256 = "sha256-NT2RlcIsFB9AvBhMxil4ZZIgx+KusMqDflj2HgQxsZg=";
+  release."1.14.0".sha256 = "sha256:1v2p5dlpviwzky2i14cj7gcgf8cr0j54bdm9fl5iz1ckx60j6nvp";
+  release."1.13.0".sha256 = "1j7s7dlnjbw222gnbrsjgmjck1yrx7h6hwm8zikcyxi0zys17w7n";
+  release."1.12.1".sha256 = "sha256-4mO6/co7NcIQSGIQJyoO8lNWXr6dqz+bIYPO/G0cPkY=";
+  release."1.11.2".sha256 = "0qk5cfh15y2zrja7267629dybd3irvxk1raz7z8qfir25a81ckd4";
+  release."1.11.1".sha256 = "10j076vc2hdcbm15m6s7b6xdzibgfcbzlkgjnlkr2vv9k13qf8kc";
+  release."1.10.1".sha256 = "1zsyx26dvj7pznfd2msl2w7zbw51q1nsdw0bdvdha6dga7ijf7xk";
+  release."1.9.7".sha256 = "0rvn12h9dpk9s4pxy32p8j0a1h7ib7kg98iv1cbrdg25y5vs85n1";
+  release."1.9.5".sha256 = "0gjdwmb6bvb5gh0a6ra48bz5fb3pr5kpxijb7a8mfydvar5i9qr6";
+  release."1.9.4".sha256 = "0nii7238mya74f9g6147qmpg6gv6ic9b54x5v85nb6q60d9jh0jq";
+  release."1.9.3".sha256 = "198irm800fx3n8n56vx1c6f626cizp1d7jfkrc6ba4iqhb62ma0z";
+  release."1.9.2".sha256 = "1rr2fr8vjkc0is7vh1461aidz2iwkigdkp6bqss4hhv0c3ijnn07";
+  release."1.8.3_8.12".sha256 = "15z2l4zy0qpw0ws7bvsmpmyv543aqghrfnl48nlwzn9q0v89p557";
   release."1.8.3_8.12".version = "1.8.3";
-  release."1.8.2_8.12".sha256  = "1n6jwcdazvjgj8vsv2r9zgwpw5yqr5a1ndc2pwhmhqfl04b5dk4y";
+  release."1.8.2_8.12".sha256 = "1n6jwcdazvjgj8vsv2r9zgwpw5yqr5a1ndc2pwhmhqfl04b5dk4y";
   release."1.8.2_8.12".version = "1.8.2";
-  release."1.8.1".sha256      = "1fbbdccdmr8g4wwpihzp4r2xacynjznf817lhijw6kqfav75zd0r";
-  release."1.8.0".sha256      = "13ywjg94zkbki22hx7s4gfm9rr87r4ghsgan23xyl3l9z8q0idd1";
-  release."1.7.0".sha256      = "1ws5cqr0xawv69prgygbl3q6dgglbaw0vc397h9flh90kxaqgyh8";
+  release."1.8.1".sha256 = "1fbbdccdmr8g4wwpihzp4r2xacynjznf817lhijw6kqfav75zd0r";
+  release."1.8.0".sha256 = "13ywjg94zkbki22hx7s4gfm9rr87r4ghsgan23xyl3l9z8q0idd1";
+  release."1.7.0".sha256 = "1ws5cqr0xawv69prgygbl3q6dgglbaw0vc397h9flh90kxaqgyh8";
   release."1.6.3_8.11".sha256 = "1j340cr2bv95clzzkkfmsjkklham1mj84cmiyprzwv20q89zr1hp";
   release."1.6.3_8.11".version = "1.6.3";
   release."1.6.2_8.11".sha256 = "06xrx0ljilwp63ik2sxxr7h617dgbch042xfcnfpy5x96br147rn";
@@ -63,27 +154,29 @@ in (mkCoqDerivation {
   release."1.6.1_8.11".version = "1.6.1";
   release."1.6.0_8.11".sha256 = "0ahxjnzmd7kl3gl38kyjqzkfgllncr2ybnw8bvgrc6iddgga7bpq";
   release."1.6.0_8.11".version = "1.6.0";
-  release."1.6.0".sha256      = "0kf99i43mlf750fr7fric764mm495a53mg5kahnbp6zcjcxxrm0b";
+  release."1.6.0".sha256 = "0kf99i43mlf750fr7fric764mm495a53mg5kahnbp6zcjcxxrm0b";
   releaseRev = v: "v${v}";
 
   buildFlags = [ "OCAMLWARN=" ];
 
   mlPlugin = true;
   useDuneifVersion = v: lib.versions.isGe "2.2.0" v || v == "dev";
-  propagatedBuildInputs = [ coq.ocamlPackages.findlib elpi ];
+  propagatedBuildInputs = [
+    coq.ocamlPackages.findlib
+    elpi
+    stdlib
+  ];
 
   meta = {
     description = "Coq plugin embedding ELPI";
     maintainers = [ lib.maintainers.cohencyril ];
     license = lib.licenses.lgpl21Plus;
   };
-
-  preBuild = ''
-    make elpi/dune || true
-  '';
-}).overrideAttrs (o:
-  lib.optionalAttrs (o.version != null
-    && (o.version == "dev" || lib.versions.isGe "2.2.0" o.version))
-  {
-    propagatedBuildInputs = o.propagatedBuildInputs ++ [ coq.ocamlPackages.ppx_optcomp ];
-  })
+}).overrideAttrs
+  (
+    o:
+    lib.optionalAttrs (o.version != null && (o.version == "dev" || lib.versions.isGe "2.2.0" o.version))
+      {
+        propagatedBuildInputs = o.propagatedBuildInputs ++ [ coq.ocamlPackages.ppx_optcomp ];
+      }
+  )
diff --git a/.nix/ocaml-overlays/elpi/default.nix b/.nix/ocaml-overlays/elpi/default.nix
deleted file mode 100644
index a40d50715..000000000
--- a/.nix/ocaml-overlays/elpi/default.nix
+++ /dev/null
@@ -1,59 +0,0 @@
-{ lib
-, buildDunePackage, camlp5
-, ocaml
-, menhir, menhirLib
-, atdgen
-, stdlib-shims
-, re, perl, ncurses
-, ppxlib, ppx_deriving
-, coqPackages
-, version ? "2.0.3"
-}:
-
-let p5 = camlp5; in
-let camlp5 = p5.override { legacy = true; }; in
-
-let fetched = coqPackages.metaFetch ({
-    release."2.0.3".sha256 = "sha256-t2z0sWPiFgp6LuR6CsH/Zk9qfxW+3QjjFcYrB6qSPgc=";
-    release."1.20.0".sha256 = "sha256-lctZAIQgOg5d+LfILtWsBVcsemV3zTZYfJfDlCxHtcA=";
-    release."1.19.2".sha256 = "sha256-dBj5Ek7PWq/8Btq/dggJUqa8cUtfvbi6EWo/lJEDOU4=";
-    release."1.18.1".sha256 = "sha256-rrIv/mVC0Ez3nU7fpnzwduIC3tI6l73DjgAbv1gd2v0=";
-    release."1.17.0".sha256 = "sha256-J8FJBeaB+2HtHjrkgNzOZJngZ2AcYU+npL9Y1HNPnzo=";
-    release."1.15.2".sha256 = "sha256-+sQYQiN3n+dlzXzi5opOjhkJZqpkNwlHZcUjaUM6+xQ=";
-    release."1.15.0".sha256 = "sha256-vpQzbkDqJPCmaBmXcBnzlWGS7djW9wWv8xslkIlXgP0=";
-    releaseRev = v: "v${v}";
-    releaseArtifact = v: if lib.versionAtLeast v "1.13.8"
-      then "elpi-${v}.tbz"
-      else "elpi-v${v}.tbz";
-    location = { domain = "github.com"; owner = "LPCIC"; repo = "elpi"; };
-  }) version;
-in
-buildDunePackage {
-  pname = "elpi";
-  inherit (fetched) version src;
-
-  patches = lib.optional (version == "1.16.5")
-    ./atd_2_10.patch;
-
-  minimalOCamlVersion = "4.07";
-
-  # atdgen is both a library and executable
-  nativeBuildInputs = [ perl ]
-  ++ [ (if lib.versionAtLeast version "1.15" || version == "dev" then menhir else camlp5) ]
-  ++ lib.optional (lib.versionAtLeast version "1.16" || version == "dev") atdgen;
-  buildInputs = [ ncurses ]
-  ++ lib.optional (lib.versionAtLeast version "1.16" || version == "dev") atdgen;
-
-  propagatedBuildInputs = [ re stdlib-shims menhirLib ppxlib ppx_deriving ];
-
-  meta = with lib; {
-    description = "Embeddable λProlog Interpreter";
-    license = licenses.lgpl21Plus;
-    maintainers = [ maintainers.vbgl ];
-    homepage = "https://github.com/LPCIC/elpi";
-  };
-
-  postPatch = ''
-    substituteInPlace elpi_REPL.ml --replace-warn "tput cols" "${ncurses}/bin/tput cols"
-  '';
-}
diff --git a/default.nix b/default.nix
index 1a24d7a18..7c656a573 100644
--- a/default.nix
+++ b/default.nix
@@ -4,8 +4,8 @@
   bundle ? null, job ? null, inNixShell ? null, src ? ./.,
 }@args:
 let auto = fetchGit {
-  url = "https://github.com/coq-community/coq-nix-toolbox.git";
-  ref = "master";
+  url = "https://github.com/proux01/coq-nix-toolbox.git";
+  ref = "elpi206";
   rev = import .nix/coq-nix-toolbox.nix;
 };
 in