diff --git a/.github/scripts/main/main.sh b/.github/scripts/main/main.sh
index 8b0d031a1a8..41256c996f2 100644
--- a/.github/scripts/main/main.sh
+++ b/.github/scripts/main/main.sh
@@ -12,7 +12,7 @@ unset-dev-version () {
 export OCAMLRUNPARAM=b
 
 (set +x ; echo -en "::group::build opam\r") 2>/dev/null
-if [[ "$OPAM_TEST" -eq 1 ]] || [[ "$OPAM_DOC" -eq 1 ]] ; then
+if [[ "$OPAM_TEST" -eq 1 ]] || [[ "$OPAM_DOC" -eq 1 ]] || [[ "$OPAM_DEPENDS" -eq 1 ]] ; then
   export OPAMROOT=$OPAMBSROOT
   # If the cached root is newer, regenerate a binary compatible root
   opam env || { rm -rf $OPAMBSROOT; init-bootstrap; }
@@ -91,6 +91,40 @@ if [[ "$OPAM_DOC" -eq 1 ]]; then
   echo '::endgroup::checking generated files'
 fi
 
+prepare_project () {
+  # warning, perform a cd
+  org=$1
+  project=$2
+
+  url="https://github.com/$org/$project"
+  dir="$CACHE/$project"
+
+  if [ ! -d "$CACHE/$project" ]; then
+    git clone "$url" "$dir"
+  fi
+  cd "$dir"
+  git fetch origin
+  if [ "$GITHUB_EVENT_NAME" = "pull_request" ] && git ls-remote --exit-code origin "$GITHUB_PR_USER/$BRANCH" ; then
+    BRANCH=$GITHUB_PR_USER/$BRANCH
+  fi
+  if git ls-remote --exit-code origin "$BRANCH"; then
+    PR_BRANCH=$BRANCH
+  elif [ "$GITHUB_EVENT_NAME" = pull_request ] && git ls-remote --exit-code origin "$GITHUB_BASE_REF"; then
+    PR_BRANCH=$GITHUB_BASE_REF
+  else
+    PR_BRANCH=master
+  fi
+  if git branch | grep -q "$PR_BRANCH"; then
+    git checkout "$PR_BRANCH"
+    git reset --hard "origin/$PR_BRANCH"
+  else
+    git checkout -b "$PR_BRANCH" "origin/$PR_BRANCH"
+  fi
+
+  test -d _opam || opam switch create . --no-install --formula '"ocaml-system"'
+  opam pin "$GITHUB_WORKSPACE" -yn --with-version to-test
+}
+
 if [ "$OPAM_TEST" = "1" ]; then
   # test if an upgrade is needed
   set +e
@@ -121,35 +155,52 @@ if [ "$OPAM_TEST" = "1" ]; then
 
   # Compile and run opam-rt
   (set +x ; echo -en "::group::opam-rt\r") 2>/dev/null
-  opamrt_url="https://github.com/ocaml-opam/opam-rt"
-  if [ ! -d $CACHE/opam-rt ]; then
-    git clone $opamrt_url  $CACHE/opam-rt
-  fi
-  cd $CACHE/opam-rt
-  git fetch origin
-  if [ "$GITHUB_EVENT_NAME" = "pull_request" ] && git ls-remote --exit-code origin "$GITHUB_PR_USER/$BRANCH" ; then
-    BRANCH=$GITHUB_PR_USER/$BRANCH
-  fi
-  if git ls-remote --exit-code origin "$BRANCH"; then
-    OPAM_RT_BRANCH=$BRANCH
-  elif [ "$GITHUB_EVENT_NAME" = pull_request ] && git ls-remote --exit-code origin "$GITHUB_BASE_REF"; then
-    OPAM_RT_BRANCH=$GITHUB_BASE_REF
-  else
-    OPAM_RT_BRANCH=master
-  fi
-  if git branch | grep -q "$OPAM_RT_BRANCH"; then
-    git checkout "$OPAM_RT_BRANCH"
-    git reset --hard "origin/$OPAM_RT_BRANCH"
-  else
-    git checkout -b "$OPAM_RT_BRANCH" "origin/$OPAM_RT_BRANCH"
-  fi
+  prepare_project "ocaml-opam" "opam-rt"
 
-  test -d _opam || opam switch create . --no-install --formula '"ocaml-system"'
-  eval $(opam env)
-  opam pin $GITHUB_WORKSPACE -yn --with-version to-test
   # opam lib pins defined in opam-rt are ignored as there is a local pin
   opam pin . -yn --ignore-pin-depends
   opam install opam-rt --deps-only opam-devel.to-test
-  make || { opam reinstall opam-client -y; make; }
+  opam exec -- make || { opam reinstall opam-client -y; opam exec -- make; }
   (set +x ; echo -en "::endgroup::opam-rt\r") 2>/dev/null
 fi
+
+test_project () {
+  org=$1
+  project=$2
+  ignore_depends=$3
+  make_cmd=$4
+
+  ignore=""
+  if [ $ignore_depends -eq 1 ]; then
+    ignore="--ignore-pin-depends"
+  fi
+
+  (set +x; echo -en "::group::depends-$project\r") 2>/dev/null
+  prepare_project "$org" "$project"
+  set +e
+  opam pin . -yn $ignore
+  opam install "$project" --deps-only opam-client.to-test
+  opam exec -- $make_cmd || { opam reinstall opam-client -y; opam exec -- $make_cmd; }
+  code=$?
+  if [ $code -ne 0 ]; then
+    DEPENDS_ERRORS="$DEPENDS_ERRORS $project"
+  fi
+  set -e
+  (set +x ; echo -en "::endgroup::depends-$project\r") 2>/dev/null
+}
+
+if [ "$OPAM_DEPENDS" = "1" ]; then
+
+  DEPENDS_ERRORS=""
+  (set +x; echo -en "::group::depends\r") 2>/dev/null
+
+  test_project "ocaml-opam" "opam-publish" 0 "make"
+  test_project "AltGr" "opam-bundle" 0 "make"
+  test_project "ocamlpro" "opam-custom-install" 1 "dune build"
+
+  if [ -n "$DEPENDS_ERRORS" ]; then
+    echo -e "\e[31mErrors detected in plugins $DEPENDS_ERRORS\e[0m";
+    exit 1
+  fi
+  (set +x ; echo -en "::endgroup::depends\r") 2>/dev/null
+fi
diff --git a/.github/scripts/main/preamble.sh b/.github/scripts/main/preamble.sh
index e15bd61422f..bf6597b4994 100644
--- a/.github/scripts/main/preamble.sh
+++ b/.github/scripts/main/preamble.sh
@@ -19,6 +19,7 @@ PATH=$OPAM_LOCAL/bin:$OCAML_LOCAL/bin:$PATH; export PATH
 OPAM_COLD=${OPAM_COLD:-0}
 OPAM_TEST=${OPAM_TEST:-0}
 OPAM_DOC=${OPAM_DOC:-0}
+OPAM_DEPENDS=${OPAM_DEPENDS:-0}
 OPAM_UPGRADE=${OPAM_UPGRADE:-0}
 
 OPAM_REPO_MAIN=https://github.com/ocaml/opam-repository.git
@@ -44,7 +45,7 @@ fi
 
 # used only for TEST jobs
 init-bootstrap () {
-  if [ "$OPAM_TEST" = "1" ] || [ "$OPAM_DOC" = "1" ] || [ -n "$SOLVER" ]; then
+  if [ "$OPAM_TEST" = "1" ] || [ "$OPAM_DOC" = "1" ] || [ "$OPAM_DEPENDS" = "1" ] || [ -n "$SOLVER" ]; then
     set -e
     export OPAMROOT=$OPAMBSROOT
     # The system compiler will be picked up
diff --git a/.github/workflows/ci.ml b/.github/workflows/ci.ml
index 2fc71589177..cd2d81a253a 100644
--- a/.github/workflows/ci.ml
+++ b/.github/workflows/ci.ml
@@ -480,6 +480,26 @@ let upgrade_job ~analyse_job ~build_linux_job ~build_windows_job ~build_macOS_jo
     ++ run "Test (upgrade)" ["bash -exu .github/scripts/main/upgrade.sh"]
     ++ end_job f
 
+let depends_job ~analyse_job ~build_linux_job ?section runner ~oc ~workflow f =
+  let platform = os_of_platform runner in
+  let host = host_of_platform platform in
+  let only_on target = only_on platform target in
+  let needs = [analyse_job; build_linux_job ] in
+  let env = [("OPAM_DEPENDS", "1")] in
+  let matrix = platform_ocaml_matrix ~fail_fast:false start_latests_ocaml in
+  let ocamlv = "${{ matrix.ocamlv }}" in
+  job ~oc ~workflow ?section ~runs_on:(Runner [platform]) ~env ~needs ~matrix ("Depends-" ^ name_of_platform platform)
+    ++ only_on Linux (run "Install bubblewrap" ["sudo apt install bubblewrap"])
+    ++ only_on Linux (run "Disable AppArmor" ["echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns"])
+    ++ checkout ()
+    ++ cache Archives
+    ++ cache OCaml platform ocamlv host
+    ++ build_cache OCaml platform ocamlv host
+    ++ cache OpamBS ocamlv "depends"
+    ++ build_cache OpamBS ocamlv "depends"
+    ++ run "Compile" ~env:[("BASE_REF_SHA", "${{ github.event.pull_request.base.sha }}"); ("PR_REF_SHA", "${{ github.event.pull_request.head.sha }}"); ("GITHUB_PR_USER", "${{ github.event.pull_request.user.login }}")] ["bash -exu .github/scripts/main/main.sh " ^ host]
+    ++ end_job f
+
 let hygiene_job (type a) ~analyse_job (platform : a platform) ~oc ~workflow f =
   job ~oc ~workflow ~section:"Around opam tests" ~runs_on:(Runner [platform]) ~needs:[analyse_job] "Hygiene"
     ++ install_sys_dune [os_of_platform platform]
@@ -557,6 +577,7 @@ let main oc : unit =
   @@ fun _ -> upgrade_job ~analyse_job ~build_linux_job ~build_windows_job ~build_macOS_job ~section:"Upgrade from 1.2 to current" Linux
   @@ fun _ -> upgrade_job ~analyse_job ~build_linux_job ~build_windows_job ~build_macOS_job MacOS
   @@ fun _ -> hygiene_job ~analyse_job (Specific (Linux, "22.04"))
+  @@ fun build_linux_job -> depends_job ~analyse_job ~build_linux_job Linux
   @@ fun _ -> end_workflow
 
 let () =
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 4b4631d2d2a..4673f511976 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -692,3 +692,55 @@ jobs:
         PR_REF_SHA: ${{ github.event.pull_request.head.sha }}
       if: contains(steps.files.outputs.modified, 'configure.ac') || contains(steps.files.outputs.modified, 'shell/install.sh') || contains(steps.files.outputs.all, 'src_ext') || contains(steps.files.outputs.all, '.github/workflows')
       run: bash -exu .github/scripts/main/hygiene.sh
+
+  Depends-Linux:
+    runs-on: ubuntu-latest
+    needs: [ Analyse, Hygiene ]
+    strategy:
+      matrix:
+        ocamlv: [ 4.14.2, 5.3.0 ]
+      fail-fast: false
+    env:
+      OPAM_DEPENDS: 1
+    steps:
+    - name: Install bubblewrap
+      run: sudo apt install bubblewrap
+    - name: Disable AppArmor
+      run: echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns
+    - name: Checkout tree
+      uses: actions/checkout@v4
+    - name: src_ext/archives and opam-repository Cache
+      id: archives
+      uses: actions/cache@v4
+      with:
+        path: |
+          src_ext/archives
+          ~/opam-repository
+        key: ${{ needs.Analyse.outputs.archives }}
+        enableCrossOsArchive: true
+    - name: OCaml ${{ matrix.ocamlv }} Cache
+      id: ocaml-cache
+      uses: actions/cache@v4
+      with:
+        path: ~/.cache/ocaml-local/**
+        key: ${{ runner.os }}-ocaml-${{ matrix.ocamlv }}-${{ needs.Analyse.outputs.ocaml-cache }}
+    - name: Create OCaml ${{ matrix.ocamlv }} cache
+      if: steps.ocaml-cache.outputs.cache-hit != 'true'
+      run: bash -exu .github/scripts/main/ocaml-cache.sh ${{ runner.os }} ${{ matrix.ocamlv }}
+    - name: opam bootstrap Cache
+      id: opam-bootstrap
+      uses: actions/cache@v4
+      with:
+        path: |
+          ${{ env.OPAMBSROOT }}/**
+          ~/.cache/opam-local/bin/**
+        key: opamdepends-${{ runner.os }}-${{ env.OPAMBSVERSION }}-${{ matrix.ocamlv }}-${{ env.OPAM_REPO_SHA }}-${{ needs.Analyse.outputs.opam-bs-cache }}
+    - name: Create opam bootstrap cache
+      if: steps.opam-bootstrap.outputs.cache-hit != 'true'
+      run: bash -exu .github/scripts/main/opam-bs-cache.sh
+    - name: Compile
+      env:
+        BASE_REF_SHA: ${{ github.event.pull_request.base.sha }}
+        PR_REF_SHA: ${{ github.event.pull_request.head.sha }}
+        GITHUB_PR_USER: ${{ github.event.pull_request.user.login }}
+      run: bash -exu .github/scripts/main/main.sh x86_64-pc-linux-gnu
diff --git a/master_changes.md b/master_changes.md
index 836232e95c4..d585e1eda2b 100644
--- a/master_changes.md
+++ b/master_changes.md
@@ -189,6 +189,7 @@ users)
   * Add OCaml 5.3/MSVC to the build matrix [#6192 @kit-ty-kate]
   * Add a test making sure `opam init` works in the absence of `OPAMROOT` [#5663 @kit-ty-kate]
   * Show Cygwin version info after loading it from the cache [#6383 @kit-ty-kate]
+  * Add a job that test plugins compilation in order to keep them synchroniser [#6394 @rjbou]
 
 ## Doc
   * Update the command to install opam to point to the new simplified url on opam.ocaml.org [#6226 @kit-ty-kate]