diff --git a/.dockerignore b/.dockerignore
index ced02564a8..75b1506fbb 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -7,3 +7,6 @@ karma-reports/
 .idea/
 .tmp/
 config.json*
+matrix-js-sdk/
+matrix-react-sdk/
+matrix-analytics-events/
\ No newline at end of file
diff --git a/.github/workflows/build_develop.yml b/.github/deactivated_workflows/build_develop.yml
similarity index 95%
rename from .github/workflows/build_develop.yml
rename to .github/deactivated_workflows/build_develop.yml
index 3a0670f978..dfc568d7c0 100644
--- a/.github/workflows/build_develop.yml
+++ b/.github/deactivated_workflows/build_develop.yml
@@ -22,9 +22,10 @@ jobs:
       - uses: actions/setup-node@v3
         with:
           cache: 'yarn'
+          node-version: 14
 
       - name: Install Dependencies
-        run: "./scripts/layered.sh"
+        run: "./scripts/layered.with.version.sh"
 
       - name: Build, Package & Upload sourcemaps
         run: "./scripts/ci_package.sh"
diff --git a/.github/workflows/dockerhub.yaml b/.github/deactivated_workflows/dockerhub.yaml
similarity index 100%
rename from .github/workflows/dockerhub.yaml
rename to .github/deactivated_workflows/dockerhub.yaml
diff --git a/.github/workflows/issue_closed.yml b/.github/deactivated_workflows/issue_closed.yml
similarity index 98%
rename from .github/workflows/issue_closed.yml
rename to .github/deactivated_workflows/issue_closed.yml
index 9bc4e76a4a..4a81c4d8a3 100644
--- a/.github/workflows/issue_closed.yml
+++ b/.github/deactivated_workflows/issue_closed.yml
@@ -11,7 +11,7 @@ jobs:
     steps:
       - uses: actions/github-script@v5
         with:
-          # PAT needed as the GITHUB_TOKEN won't be able to see cross-references from other orgs (matrix-org)
+          # PAT  needed as the GITHUB_TOKEN won't be able to see cross-references from other orgs (matrix-org)
           github-token: ${{ secrets.ELEMENT_BOT_TOKEN }}
           script: |
             const variables = {
diff --git a/.github/workflows/pull_request.yaml b/.github/deactivated_workflows/pull_request.yaml
similarity index 100%
rename from .github/workflows/pull_request.yaml
rename to .github/deactivated_workflows/pull_request.yaml
diff --git a/.github/workflows/sonarqube.yml b/.github/deactivated_workflows/sonarqube.yml
similarity index 100%
rename from .github/workflows/sonarqube.yml
rename to .github/deactivated_workflows/sonarqube.yml
diff --git a/.github/workflows/triage-assigned.yml b/.github/deactivated_workflows/triage-assigned.yml
similarity index 100%
rename from .github/workflows/triage-assigned.yml
rename to .github/deactivated_workflows/triage-assigned.yml
diff --git a/.github/workflows/triage-incoming.yml b/.github/deactivated_workflows/triage-incoming.yml
similarity index 100%
rename from .github/workflows/triage-incoming.yml
rename to .github/deactivated_workflows/triage-incoming.yml
diff --git a/.github/workflows/triage-labelled.yml b/.github/deactivated_workflows/triage-labelled.yml
similarity index 100%
rename from .github/workflows/triage-labelled.yml
rename to .github/deactivated_workflows/triage-labelled.yml
diff --git a/.github/workflows/triage-move-review-requests.yml b/.github/deactivated_workflows/triage-move-review-requests.yml
similarity index 100%
rename from .github/workflows/triage-move-review-requests.yml
rename to .github/deactivated_workflows/triage-move-review-requests.yml
diff --git a/.github/workflows/triage-priority-bugs.yml b/.github/deactivated_workflows/triage-priority-bugs.yml
similarity index 100%
rename from .github/workflows/triage-priority-bugs.yml
rename to .github/deactivated_workflows/triage-priority-bugs.yml
diff --git a/.github/workflows/triage-unlabelled.yml b/.github/deactivated_workflows/triage-unlabelled.yml
similarity index 100%
rename from .github/workflows/triage-unlabelled.yml
rename to .github/deactivated_workflows/triage-unlabelled.yml
diff --git a/.github/workflows/upgrade_dependencies.yml b/.github/deactivated_workflows/upgrade_dependencies.yml
similarity index 100%
rename from .github/workflows/upgrade_dependencies.yml
rename to .github/deactivated_workflows/upgrade_dependencies.yml
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index ab94c0e9ca..2e26697d2e 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1,3 +1,5 @@
+#Build the application
+#tchap modification : use "./scripts/layered.with.version.sh" instead of "./scripts/layered.sh"
 name: Build
 on:
   pull_request: { }
@@ -18,9 +20,10 @@ jobs:
       - uses: actions/setup-node@v3
         with:
           cache: 'yarn'
+          node-version: 14
 
       - name: Install Dependencies
-        run: "./scripts/layered.sh"
+        run: "./scripts/layered.with.version.sh"
 
       - name: Build
         run: "yarn build"
diff --git a/.github/workflows/static_analysis.yaml b/.github/workflows/static_analysis.yaml
index 98cf39a156..c34eb2a9f9 100644
--- a/.github/workflows/static_analysis.yaml
+++ b/.github/workflows/static_analysis.yaml
@@ -1,3 +1,5 @@
+#Run a static analysis
+#tchap modification : use "./scripts/layered.with.version.sh" instead of "./scripts/layered.sh"
 name: Static Analysis
 on:
   pull_request: { }
@@ -19,16 +21,18 @@ jobs:
       - uses: actions/setup-node@v3
         with:
           cache: 'yarn'
+          node-version: 14
 
       - name: Install Dependencies
-        run: "./scripts/layered.sh"
+        run: "./scripts/layered.with.version.sh"
 
       - name: Typecheck
         run: "yarn run lint:types"
 
-  i18n_lint:
-    name: "i18n Check"
-    uses: matrix-org/matrix-react-sdk/.github/workflows/i18n_check.yml@develop
+# tchap : tchap does not use extensively i18n 
+# i18n_lint:
+#    name: "i18n Check"
+#    uses: matrix-org/matrix-react-sdk/.github/workflows/i18n_check.yml@develop
 
   js_lint:
     name: "ESLint"
@@ -39,6 +43,7 @@ jobs:
       - uses: actions/setup-node@v3
         with:
           cache: 'yarn'
+          node-version: 14
 
       # Does not need branch matching as only analyses this layer
       - name: Install Deps
@@ -56,26 +61,29 @@ jobs:
       - uses: actions/setup-node@v3
         with:
           cache: 'yarn'
+          node-version: 14
 
       # Needs branch matching as it inherits .stylelintrc.js from matrix-react-sdk
       - name: Install Dependencies
-        run: "./scripts/layered.sh"
+        run: "./scripts/layered.with.version.sh"
 
       - name: Run Linter
         run: "yarn run lint:style"
 
-  analyse_dead_code:
-    name: "Analyse Dead Code"
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
+# tchap :  analyse:unused-exports does not work well with tchap customisations, it raises exception for "default export" not used
+  #analyse_dead_code:
+  #   name: "Analyse Dead Code"
+  #   runs-on: ubuntu-latest
+  #   steps:
+  #     - uses: actions/checkout@v2
 
-      - uses: actions/setup-node@v3
-        with:
-          cache: 'yarn'
+  #     - uses: actions/setup-node@v3
+  #       with:
+  #         cache: 'yarn'
+  #         node-version: 14
 
-      - name: Install Deps
-        run: "scripts/layered.sh"
+  #     - name: Install Deps
+  #       run: "scripts/layered.with.version.sh"
 
-      - name: Dead Code Analysis
-        run: "yarn run analyse:unused-exports"
+  #     - name: Dead Code Analysis
+  #       run: "yarn run analyse:unused-exports"
diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index ea3bbf8b82..75d9ec8745 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -1,3 +1,5 @@
+#Run the tests
+#tchap modification : use "./scripts/layered.with.version.sh" instead of "./scripts/layered.sh"
 name: Tests
 on:
   pull_request: { }
@@ -21,9 +23,10 @@ jobs:
         uses: actions/setup-node@v3
         with:
           cache: 'yarn'
+          node-version: 14
 
       - name: Install Dependencies
-        run: "./scripts/layered.sh"
+        run: "./scripts/layered.with.version.sh"
 
       - name: Run tests with coverage
         run: "yarn coverage --ci"
diff --git a/package.json b/package.json
index 0582405d58..e92456676c 100644
--- a/package.json
+++ b/package.json
@@ -25,9 +25,6 @@
     "package.json",
     "contribute.json"
   ],
-  "engines": {
-    "node": ">=14.19 <15"
-  },
   "style": "bundle.css",
   "scripts": {
     "i18n": "matrix-gen-i18n",
@@ -218,5 +215,8 @@
   "jestSonar": {
     "reportPath": "coverage",
     "sonar56x": true
+  },
+  "engines": {
+    "node": ">=14.19 <15"
   }
 }
diff --git a/scripts/fetchdep.sh b/scripts/fetchdep.sh
new file mode 100755
index 0000000000..e16b7279c4
--- /dev/null
+++ b/scripts/fetchdep.sh
@@ -0,0 +1,81 @@
+#!/bin/bash
+#copied from matrix-react-sdk/scripts
+
+set -x
+
+deforg="$1"
+defrepo="$2"
+defbranch="$3"
+
+[ -z "$defbranch" ] && defbranch="develop"
+
+rm -r "$defrepo" || true
+
+PR_ORG=${PR_ORG:-"matrix-org"}
+PR_REPO=${PR_REPO:-"matrix-react-sdk"}
+
+# A function that clones a branch of a repo based on the org, repo and branch
+clone() {
+    org=$1
+    repo=$2
+    branch=$3
+    if [ -n "$branch" ]
+    then
+        echo "Trying to use $org/$repo#$branch"
+        # Disable auth prompts: https://serverfault.com/a/665959
+        GIT_TERMINAL_PROMPT=0 git clone https://github.com/$org/$repo.git $repo --branch "$branch" --depth 1 && exit 0
+    fi
+}
+
+# A function that gets info about a PR from the GitHub API based on its number
+getPRInfo() {
+    number=$1
+    if [ -n "$number" ]; then
+        echo "Getting info about a PR with number $number"
+
+        apiEndpoint="https://api.github.com/repos/$PR_ORG/$PR_REPO/pulls/$number"
+
+        head=$(curl $apiEndpoint | jq -r '.head.label')
+    fi
+}
+
+# Some CIs don't give us enough info, so we just get the PR number and ask the
+# GH API for more info - "fork:branch". Some give us this directly.
+if [ -n "$BUILDKITE_BRANCH" ]; then
+    # BuildKite
+    head=$BUILDKITE_BRANCH
+elif [ -n "$PR_NUMBER" ]; then
+    # GitHub
+    getPRInfo $PR_NUMBER
+elif [ -n "$REVIEW_ID" ]; then
+    # Netlify
+    getPRInfo $REVIEW_ID
+fi
+
+# for forks, $head will be in the format "fork:branch", so we split it by ":"
+# into an array. On non-forks, this has the effect of splitting into a single
+# element array given ":" shouldn't appear in the head - it'll just be the
+# branch name. Based on the results, we clone.
+BRANCH_ARRAY=(${head//:/ })
+TRY_ORG=$deforg
+TRY_BRANCH=${BRANCH_ARRAY[0]}
+if [[ "$head" == *":"* ]]; then
+    # ... but only match that fork if it's a real fork
+    if [ "${BRANCH_ARRAY[0]}" != "$PR_ORG" ]; then
+        TRY_ORG=${BRANCH_ARRAY[0]}
+    fi
+    TRY_BRANCH=${BRANCH_ARRAY[1]}
+fi
+clone ${TRY_ORG} $defrepo ${TRY_BRANCH}
+
+# Try the target branch of the push or PR.
+if [ -n "$GITHUB_BASE_REF" ]; then
+    clone $deforg $defrepo $GITHUB_BASE_REF
+elif [ -n "$BUILDKITE_PULL_REQUEST_BASE_BRANCH" ]; then
+    clone $deforg $defrepo $BUILDKITE_PULL_REQUEST_BASE_BRANCH
+fi
+
+# Try HEAD which is the branch name in Netlify (not BRANCH which is pull/xxxx/head for PR builds)
+clone $deforg $defrepo $HEAD
+# Use the default branch as the last resort.
+clone $deforg $defrepo $defbranch
diff --git a/scripts/layered.with.version.sh b/scripts/layered.with.version.sh
new file mode 100755
index 0000000000..930d3288d9
--- /dev/null
+++ b/scripts/layered.with.version.sh
@@ -0,0 +1,54 @@
+#!/bin/bash
+#inspired from ./layered.sh
+set -x
+
+# Creates a layered environment with the full repo for the app and SDKs cloned
+# and linked. This gives an tchap-web dev environment ready to build with
+# matching branches of react-sdk's dependencies so that changes can be tested
+# in tchap-web.
+
+# Note that this style is different from the recommended developer setup: this
+# file nests js-sdk and matrix-react-sdk inside element-web, while the local
+# development setup places them all at the same level. We are nesting them here
+# because some CI systems do not allow moving to a directory above the checkout
+# for the primary repo (element-web in this case).
+
+# Install dependencies, as we'll be using fetchdep.sh from matrix-react-sdk
+yarn install --pure-lockfile
+
+# Pass appropriate repo to fetchdep.sh (not needed for tchap-web)
+#export PR_ORG=vector-im
+#export PR_REPO=element-web
+
+#tchap added : grep matrix dependencies version from package.json
+export MATRIX_JS_SDK_VERSION=$(awk -F \" '/"matrix-js-sdk": ".+"/ { print $4; exit; }' package.json)
+export MATRIX_REACT_SDK_VERSION=$(awk -F \" '/"matrix-react-sdk": ".+"/ { print $4; exit; }' package.json)
+
+# Set up the js-sdk first
+./scripts/fetchdep.sh matrix-org matrix-js-sdk v$MATRIX_JS_SDK_VERSION
+pushd matrix-js-sdk
+yarn link
+yarn install --pure-lockfile
+popd
+
+# Also set up matrix-analytics-events so we get the latest from
+# the main branch or a branch with matching name
+./scripts/fetchdep.sh matrix-org matrix-analytics-events main
+pushd matrix-analytics-events
+yarn link
+yarn install --pure-lockfile
+yarn build:ts
+popd
+
+# Now set up the react-sdk
+./scripts/fetchdep.sh matrix-org matrix-react-sdk v$MATRIX_REACT_SDK_VERSION
+pushd matrix-react-sdk
+yarn link
+yarn link matrix-js-sdk
+yarn link @matrix-org/analytics-events
+yarn install --pure-lockfile
+popd
+
+# Link the layers into element-web
+yarn link matrix-js-sdk
+yarn link matrix-react-sdk