diff --git a/.github/workflows/debug-glibc.yml b/.github/workflows/debug-glibc.yml
new file mode 100644
index 00000000..29a8975d
--- /dev/null
+++ b/.github/workflows/debug-glibc.yml
@@ -0,0 +1,44 @@
+name: Debug nix develop environment
+
+on:
+  workflow_dispatch:
+
+jobs:
+  debug-nix:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v3
+
+      - name: Install Nix
+        uses: cachix/install-nix-action@v24
+
+      - name: Enter nix develop shell
+        run: |
+          nix develop --command bash -c '
+            echo "🔧 Nix develop shell entered"
+
+            echo
+            echo "🔍 Checking for stdlib.h"
+            find /nix/store -name "stdlib.h" || echo "❌ stdlib.h not found"
+
+            echo
+            echo "📂 Checking expected glibc include path"
+            ls -l /nix/store/*glibc*/include/stdlib.h || echo "❌ /glibc*/include/stdlib.h not found"
+
+            echo
+            echo "🧠 C compiler version and paths:"
+            gcc --version
+            echo
+
+            echo "📤 GCC include paths:"
+            echo | gcc -E -x c -v -
+
+            echo
+            echo "📤 g++ include paths:"
+            echo | g++ -E -x c++ -v -
+
+            echo
+            echo "✅ Diagnostic complete"
+          '
\ No newline at end of file
diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index fb04b7a2..d5e5f68d 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -2,30 +2,32 @@ name: "test"
 
 on:
   push:
-    branches: [ main, develop ]
+    branches: [main, develop]
   pull_request:
-    branches: [ main, develop ]
+    branches: [main, develop]
 
 jobs:
   testbuild:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     steps:
       - uses: actions/checkout@v4
 
-      # 🔴 REQUIRED: minimal system bootstrap so bindgen/libclang can start
-
       - name: Install system dependencies
         run: |
           sudo apt-get update
-          sudo apt-get install -y libclang-14-dev libstdc++6 clang
-
-      - name: Install nix
+          sudo apt-get install -y \
+            libclang-dev \
+            libstdc++6 \
+            clang \
+            cmake \
+            pkg-config
+
+      - name: Install Nix
         uses: cachix/install-nix-action@v27
         with:
-          install_url: https://releases.nixos.org/nix/nix-2.23.3/install
           extra_nix_config: |
-            experimental-features = flakes nix-command
+            experimental-features = nix-command flakes
 
       - uses: cachix/cachix-action@v15
         with:
@@ -33,4 +35,8 @@ jobs:
 
       - name: Install and test
         run: |
-          nix develop --command bash -c "npm i && npm t"
\ No newline at end of file
+          export LIBCLANG_PATH=$(nix eval --raw .#devShells.x86_64-linux.default.buildInputs | grep libclang | head -1)/lib
+          export LD_LIBRARY_PATH=$(nix eval --raw .#devShells.x86_64-linux.default.buildInputs | grep llvm | head -1)/lib:$LD_LIBRARY_PATH
+          export NIX_CFLAGS_COMPILE="-isystem $(nix eval --raw .#devShells.x86_64-linux.default.buildInputs | grep glibc | grep dev | head -1)/include"
+          export NIX_LDFLAGS="-L$(nix eval --raw .#devShells.x86_64-linux.default.buildInputs | grep glibc | grep -v dev | head -1)/lib"
+          nix develop --command bash -c "npm install && npm test"
diff --git a/ARCHITECTURE.md b/ARCHITECTURE.md
index 38ec99fd..d761f396 100644
--- a/ARCHITECTURE.md
+++ b/ARCHITECTURE.md
@@ -175,4 +175,5 @@ If you’re unsure where code belongs, ask:
 
 If the answer is **no**, it does not belong in `shared/` or `happ/`.
 
-That single heuristic will prevent most architectural violations.
\ No newline at end of file
+That single heuristic will prevent most architectural violations.
+
diff --git a/flake.nix b/flake.nix
index da7baf4b..a975e481 100644
--- a/flake.nix
+++ b/flake.nix
@@ -20,33 +20,38 @@
             # Pull in holonix dev shell
             inputsFrom = [ inputs'.holonix.devShells.default ];
 
-            # Extra native tools (incl. libclang + libstdc++ for CI)
-            nativeBuildInputs = [
-                          pkgs.libsodium
-                          pkgs.pkg-config
-                          pkgs.llvmPackages.libunwind
-                          pkgs.llvmPackages.libclang        # ✅ Required by bindgen
-                          pkgs.llvmPackages.clang-unwrapped # ✅ Needed to satisfy some crates
-                          pkgs.stdenv.cc.cc.lib             # ✅ Pulls in libstdc++.so
-                          pkgs.cmake
-                        ];
-
             packages = with pkgs; [
+              # ✅ Native build toolchain + headers required on CI (Ubuntu)
+              stdenv.cc
+              glibc.dev
+
+              # ✅ For crates like bindgen / cmake / datachannel-sys
+              llvmPackages.libclang
+              llvmPackages.clang-unwrapped
+              llvmPackages.libunwind
+              pkg-config
+              cmake
+              libsodium
+
+              # App-specific tools
               nodejs_22
               binaryen
             ];
 
             shellHook =
               ''
-                export PS1='$begin:math:display$\\033\[1\;34m$end:math:display$[holonix:\w]\$$begin:math:display$\\033\[0m$end:math:display$ '
+                export PS1='\[\033[1;34m\][holonix:\w]\$\[\033[0m\] '
 
-                # Cross-platform: modern CMake policy + reduce configure flakiness
+                # 🛠 For CMake-based crates and general safety
                 export CMAKE_ARGS="''${CMAKE_ARGS:-} -DCMAKE_POLICY_VERSION_MINIMUM=3.10"
                 export CMAKE_BUILD_PARALLEL_LEVEL="''${CMAKE_BUILD_PARALLEL_LEVEL:-1}"
+
+                # ✅ Critical for CI (Ubuntu) to find stdlib headers + libs
+                export NIX_CFLAGS_COMPILE="-isystem ${pkgs.glibc.dev}/include"
+                export NIX_LDFLAGS="-L${pkgs.glibc}/lib -L${pkgs.stdenv.cc.cc.lib}/lib"
               ''
-              # macOS-only: use Apple's toolchain for native deps
               + pkgs.lib.optionalString pkgs.stdenv.isDarwin ''
-                # Requires Xcode CLT: xcode-select --install
+                # macOS-only: use Apple's toolchain
                 export CC="$(xcrun -f clang)"
                 export CXX="$(xcrun -f clang++)"
                 export AR="$(xcrun -f ar)"