diff --git a/.gitea/workflows/mcp-tests.yml b/.gitea/workflows/mcp-tests.yml
index 5b122ae..3ced0af 100644
--- a/.gitea/workflows/mcp-tests.yml
+++ b/.gitea/workflows/mcp-tests.yml
@@ -31,5 +31,4 @@ jobs:
 
       - name: Run MCP lint/format/tests via nix-shell
         run: |
-          repo_root="$PWD"
-          MCP_TESTS_WORKDIR="$repo_root" nix run .#mcp-tests
+          nix run .#mcp-tests
diff --git a/parts/packages.nix b/parts/packages.nix
index 0025619..13950a7 100644
--- a/parts/packages.nix
+++ b/parts/packages.nix
@@ -36,27 +36,7 @@
           ruff
         ];
         text = ''
-          start_dir="$PWD"
-          if [ -n "''${MCP_TESTS_WORKDIR:-}" ]; then
-            cd "''${MCP_TESTS_WORKDIR}"
-          elif [ -n "''${GITEA_WORKSPACE:-}" ]; then
-            cd "''${GITEA_WORKSPACE}"
-          elif [ -n "''${GITHUB_WORKSPACE:-}" ]; then
-            cd "''${GITHUB_WORKSPACE}"
-          elif command -v git >/dev/null 2>&1; then
-            repo_root="$(git rev-parse --show-toplevel 2>/dev/null || true)"
-            if [ -n "$repo_root" ]; then
-              cd "$repo_root"
-            fi
-          fi
-          while [ ! -x ./scripts/mcp-server/run-tests.sh ]; do
-            if [ "$PWD" = "/" ]; then
-              echo "Could not find executable scripts/mcp-server/run-tests.sh starting from $start_dir" >&2
-              exit 1
-            fi
-            cd ..
-          done
-          exec bash ./scripts/mcp-server/run-tests.sh "$@"
+          exec bash ${inputs.self}/scripts/mcp-server/run-tests.sh "$@"
         '';
       };
     in
diff --git a/scripts/mcp-server/run-tests.sh b/scripts/mcp-server/run-tests.sh
index ad18d58..51a3212 100755
--- a/scripts/mcp-server/run-tests.sh
+++ b/scripts/mcp-server/run-tests.sh
@@ -8,10 +8,13 @@ cd "$here"
 
 cache_root="${TMPDIR:-/tmp}/mcp-tests-cache"
 mkdir -p "$cache_root"
+export HOME="${TMPDIR:-/tmp}/mcp-tests-home"
+mkdir -p "$HOME"
 export XDG_CACHE_HOME="$cache_root/xdg"
 export RUFF_CACHE_DIR="$cache_root/ruff"
 export MYPY_CACHE_DIR="$cache_root/mypy"
 export PYTEST_ADDOPTS="${PYTEST_ADDOPTS:-} -o cache_dir=$cache_root/pytest"
+export PYTHONDONTWRITEBYTECODE=1
 
 fix=false
 for arg in "$@"; do