diff --git a/cli/src/test/all-tests-functions.sh b/cli/src/test/all-tests-functions.sh
index fff32b027..ff296172e 100644
--- a/cli/src/test/all-tests-functions.sh
+++ b/cli/src/test/all-tests-functions.sh
@@ -43,22 +43,40 @@ function doDownloadSnapshot () {
     local url
     # Change OS type based on github workflow matrix.os name
     local osType
-    if [ "${MATRIX_OS}" == "windows-latest" ]; then
-      osType="windows-x64"
-    elif [ "${MATRIX_OS}" == "ubuntu-latest" ]; then
-      osType="linux-x64"
-    elif [ "${MATRIX_OS}" == "macos-latest" ]; then
-      osType="mac-arm64"
-    elif [ "${MATRIX_OS}" == "macos-13" ]; then
-      osType="mac-x64"
-    fi
-    url=$(grep "href=\"https://.*${osType}.tar.gz" "$pageHtmlLocal" | grep -o "https://.*${osType}.tar.gz" | cut -f1 -d"\"")
+    osType=$(doGetOsType)
+    url=$(grep "href=\"https://.*${osType}.tar.gz" "$pageHtmlLocal" | grep -o "https://[^\"]*${osType}.tar.gz" | head -1)
     echo "Trying to download IDEasy for OS: ${osType} from: ${url} to: ${IDEASY_COMPRESSED_FILE:?} ..."
     curl -o "${IDEASY_COMPRESSED_FILE:?}" "$url"
     rm "${pageHtmlLocal:?}"
   fi
 }
 
+function doGetOsType() {
+  local osType
+  case "$OSTYPE" in
+    msys*|cygwin*|win32*)
+      osType="windows-x64"
+      ;;
+    linux*|gnu*)
+      osType="linux-x64"
+      ;;
+    darwin*|macos*)
+      # Try to distinguish between Apple Silicon and Intel Macs
+      if sysctl -n machdep.cpu.brand_string 2>/dev/null | grep -qi "Apple"; then
+        osType="mac-arm64"
+      else
+        osType="mac-x64"
+      fi
+      ;;
+    *)
+      echo "Unknown OSTYPE: $OSTYPE. Falling back to windows (most common developer machine)." >&2
+      osType="windows-x64"
+      ;;
+  esac
+  echo "Detected OS type: ${osType}" >&2
+  echo "$osType"
+}
+
 
 function doExtract() {
   echo "Extracting IDEasy archive: ${IDEASY_COMPRESSED_FILE} to: ${IDEASY_DIR}"
@@ -86,7 +104,8 @@ function doError() {
 }
 
 function doIsMacOs() {
-  if [ "${OSTYPE:0:6}" = "darwin" ]
+  local osType=$(doGetOsType)
+  if [ "$osType" = "mac-arm64" ] || [ "$osType" = "mac-x64" ]
   then
     return
   fi
@@ -94,7 +113,8 @@ function doIsMacOs() {
 }
 
 function doIsWindows() {
-  if [ "${OSTYPE}" = "cygwin" ] || [ "${OSTYPE}" = "msys" ]
+  local osType=$(doGetOsType)
+  if [ "$osType" = "windows-x64" ]
   then
     return
   fi
diff --git a/cli/src/test/all-tests.sh b/cli/src/test/all-tests.sh
index d3ebb8f31..0b9be1e27 100755
--- a/cli/src/test/all-tests.sh
+++ b/cli/src/test/all-tests.sh
@@ -8,23 +8,55 @@ touch "${HOME}"/.ide/.license.agreement
 
 source "$(dirname "${0}")"/all-tests-functions.sh
 
-MATRIX_OS="$1"
+# Remove side-effects
+BAK_IDE_ROOT="${IDE_ROOT}"
+BAK_PATH="${PATH}"
+DEBUG_INTEGRATION_TEST_PREFIX="${HOME}/tmp/ideasy-integration-test-debug"
+
+# Create backups of shell RC files to prevent destroying user's existing configuration
+BAK_BASHRC=""
+BAK_ZSHRC=""
+if [ -f "$HOME/.bashrc" ]; then
+  BAK_BASHRC="$HOME/.bashrc.ideasy-test-backup"
+  cp "$HOME/.bashrc" "$BAK_BASHRC"
+fi
+if [ -f "$HOME/.zshrc" ]; then
+  BAK_ZSHRC="$HOME/.zshrc.ideasy-test-backup"
+  cp "$HOME/.zshrc" "$BAK_ZSHRC"
+fi
+
+trap "export PATH=\"${BAK_PATH}\" && export IDE_ROOT=\"${BAK_IDE_ROOT}\" && rm -rf \"${DEBUG_INTEGRATION_TEST_PREFIX}\" && doRestoreRcFiles && echo \"PATH, IDE_ROOT, and shell RC files restored\"" EXIT
+
+function doRestoreRcFiles() {
+  # Restore shell RC files from backups to preserve user's existing configuration
+  if [ -n "$BAK_BASHRC" ] && [ -f "$BAK_BASHRC" ]; then
+    mv "$BAK_BASHRC" "$HOME/.bashrc"
+    echo "Restored ~/.bashrc from backup"
+  fi
+  if [ -n "$BAK_ZSHRC" ] && [ -f "$BAK_ZSHRC" ]; then
+    mv "$BAK_ZSHRC" "$HOME/.zshrc"
+    echo "Restored ~/.zshrc from backup"
+  fi
+}
+
+function doResetVariables() {
+  IDE_HOME="${DEBUG_INTEGRATION_TEST}/home-dir"
+  export IDE_ROOT="${IDE_HOME}/projects"
+  IDEASY_DIR="${IDE_ROOT}/_ide"
+  FUNCTIONS="${IDEASY_DIR}/installation/functions"
+  IDE="${DEBUG_INTEGRATION_TEST}/home-dir/projects/_ide/bin/${BINARY_FILE_NAME}"
+  TEST_RESULTS_FILE="${IDE_ROOT}/testResults"
+}
+
 # Switch IDEasy binary file name based on github workflow matrix.os name (first argument of all-tests.sh)
 BINARY_FILE_NAME="ideasy"
-if [ "${MATRIX_OS}" == "windows-latest" ]; then
+if doIsWindows; then
   BINARY_FILE_NAME="ideasy.exe"
 fi
 
 START_TIME=$(date '+%Y-%m-%d_%H-%M-%S')
-
-DEBUG_INTEGRATION_TEST_PREFIX="${HOME}/tmp/ideasy-integration-test-debug"
 DEBUG_INTEGRATION_TEST="${DEBUG_INTEGRATION_TEST_PREFIX}-${START_TIME}"
-IDE_HOME="${DEBUG_INTEGRATION_TEST}/home-dir"
-export IDE_ROOT="${IDE_HOME}/projects"
-IDEASY_DIR="${IDE_ROOT}/_ide"
-FUNCTIONS="${IDEASY_DIR}/installation/functions"
-IDE="${DEBUG_INTEGRATION_TEST}/home-dir/projects/_ide/bin/${BINARY_FILE_NAME}"
-TEST_RESULTS_FILE="${IDE_ROOT}/testResults"
+doResetVariables
 
 test_files_directory=$(realpath "$0" | xargs dirname)
 
@@ -35,6 +67,7 @@ total=0
 function doTestsInner() {
   # Note: requires var test_files_directory to be set.
   for testpath in "${test_files_directory:?}/integration-tests"/*; do
+    doResetVariables
     testcase="${testpath/*\//}"
     echo "Running test #${total}: ${testcase} (${testpath})"
 
@@ -69,8 +102,6 @@ function doDisplayResults() {
   while read -r line; do echo -e "${line}"; done < "${TEST_RESULTS_FILE}"
 }
 
-
-
 function doTests () {
   doTestsInner
   echo -e "\n*****************************************************"
@@ -114,11 +145,22 @@ function main () {
 
   # upgrade to latest snapshot
   echo "Upgrading IDEasy to latest SNAPSHOT"
-  $IDE -d --batch upgrade --mode=snapshot
+  $IDE -d --batch upgrade --mode=snapshot || echo "Upgrade failed, continuing with downloaded version"
 
   # source functions (resets IDEasy)
   echo "Sourcing functions to: ${FUNCTIONS}"
-  source "${FUNCTIONS:?}"
+  # Add IDE bin to PATH so ideasy command can be found
+  export PATH="${IDEASY_DIR}/bin:$PATH"
+  # Try installation path first, then fall back to root
+  if [ -f "${FUNCTIONS:?}" ]; then
+    source "${FUNCTIONS:?}"
+  elif [ -f "${IDEASY_DIR}/functions" ]; then
+    echo "Using functions from root: ${IDEASY_DIR}/functions"
+    source "${IDEASY_DIR}/functions"
+  else
+    echo "ERROR: Could not find functions file"
+    exit 1
+  fi
 
   echo "Checking version after upgrade"
   ide -v
diff --git a/cli/src/test/integration-tests/force-install.sh b/cli/src/test/integration-tests/force-install.sh
new file mode 100644
index 000000000..cc0d4d0b3
--- /dev/null
+++ b/cli/src/test/integration-tests/force-install.sh
@@ -0,0 +1,80 @@
+#!/bin/bash
+
+# Integration test to reproduce the issue where force install (-f) breaks environment 
+# for subsequent tests when executed in alphabetical order
+
+echo "Running force install integration test to reproduce environment interference issue"
+
+# Capture initial environment state
+echo "=== Initial Environment State ==="
+env | grep -E "IDE|PATH" | sort > /tmp/env_initial.txt
+echo "IDE_ROOT: '$IDE_ROOT'"
+echo "PATH: '$PATH'"
+
+# Create a dummy .gitconfig file for testing
+touch "$HOME"/.gitconfig
+
+# Capture environment variables before force install
+echo "=== Environment before force install ==="
+env | sort > /tmp/env_before_force.txt
+echo "Shell RC files before:"
+echo "~/.bashrc exists: $(test -f ~/.bashrc && echo "yes" || echo "no")"
+if [ -f ~/.bashrc ]; then
+  echo "Last 20 lines of ~/.bashrc:"
+  tail -20 ~/.bashrc
+fi
+
+# Run force install to reproduce the issue
+echo "=== Running force install ==="
+$IDE -f install
+
+# Capture environment variables after force install  
+echo "=== Environment after force install ==="
+env | sort > /tmp/env_after_force.txt
+echo "Shell RC files after:"
+echo "~/.bashrc exists: $(test -f ~/.bashrc && echo "yes" || echo "no")" 
+if [ -f ~/.bashrc ]; then
+  echo "Last 20 lines of ~/.bashrc:"
+  tail -20 ~/.bashrc
+fi
+
+# Show the differences
+echo "=== Environment variable differences ==="
+diff /tmp/env_before_force.txt /tmp/env_after_force.txt || true
+
+# Test that the git longpaths configuration gets set (original test purpose)
+echo "=== Testing git longpaths configuration ==="
+if doIsWindows; then
+  gitconfig_path="$HOME"/.gitconfig
+  fileContent=$(cat "$gitconfig_path")
+  assertThat "$fileContent" contains "longpaths"
+else
+  echo "Skipping git longpaths test - only applicable on Windows"
+fi
+
+# Test that subsequent IDE commands still work
+echo "=== Testing subsequent IDE commands ==="
+ide_version_output=$($IDE -v 2>&1)
+if [[ $? -eq 0 ]]; then
+  echo "SUCCESS: IDE version command works after force install"
+  echo "Version output: $ide_version_output"
+else
+  echo "FAILURE: IDE version command failed after force install"
+  echo "Error output: $ide_version_output"
+fi
+
+# Test ide env command
+echo "=== Testing ide env command ==="
+ide_env_output=$($IDE env --bash 2>&1)
+if [[ $? -eq 0 ]]; then
+  echo "SUCCESS: IDE env command works after force install"
+  echo "Environment variables count: $(echo "$ide_env_output" | wc -l)"
+else
+  echo "FAILURE: IDE env command failed after force install" 
+  echo "Error output: $ide_env_output"
+fi
+
+# Clean up temporary files
+rm -f /tmp/env_initial.txt /tmp/env_before_force.txt /tmp/env_after_force.txt
+
+echo "Force install test completed"