diff --git a/actions/environment-setup/action.yml b/actions/environment-setup/action.yml
index 834fecf..d3f3065 100644
--- a/actions/environment-setup/action.yml
+++ b/actions/environment-setup/action.yml
@@ -185,6 +185,27 @@ runs:
         CONFIG_FILE: ${{ inputs.config }}
       run: ${{ github.action_path }}/scripts/parse-config.sh "$CONFIG_FILE"
 
+    # ══════════════════════════════════════════════════════════════════════════
+    # 🧹 FREE DISK SPACE (optional, Linux only)
+    # ══════════════════════════════════════════════════════════════════════════
+    # Runs before any heavy install/compile steps so they see a fresh ~10–14 GB.
+    # GitHub-hosted ubuntu runners pre-install Android SDK, .NET, Haskell, large
+    # Docker images, etc. — none of which we need for a typical Rust/Nx build.
+    # Gated on `free_disk_space: true` in .environment.yml so the action remains
+    # opt-in (the cleanup takes ~30–60s and isn't needed for small workloads).
+
+    - name: Free disk space
+      if: steps.config.outputs.free_disk_space == 'true' && runner.os == 'Linux'
+      uses: jlumbroso/free-disk-space@v1.3.1
+      with:
+        tool-cache: false       # keep actions/cache, Node, Python, Go pre-installs
+        android: true
+        dotnet: true
+        haskell: true
+        large-packages: false   # slow and we don't need most of it gone
+        swap-storage: false     # keep swap — Rust linker still benefits
+        docker-images: true
+
     # ══════════════════════════════════════════════════════════════════════════
     # ✅ VALIDATE CI ENV VARS (cargo-critical)
     # ══════════════════════════════════════════════════════════════════════════
diff --git a/actions/environment-setup/schema.json b/actions/environment-setup/schema.json
index 7f6f195..965e961 100644
--- a/actions/environment-setup/schema.json
+++ b/actions/environment-setup/schema.json
@@ -173,6 +173,11 @@
       ]
     },
 
+    "free_disk_space": {
+      "type": "boolean",
+      "description": "Free ~10–14 GB by purging pre-installed runner images content (Android SDK, .NET, Haskell, Docker images we won't use, etc.) via jlumbroso/free-disk-space. Runs first in the setup flow before any other step. Linux runners only."
+    },
+
     "services": {
       "type": "object",
       "description": "External daemons installed onto the runner's PATH so tests can spawn them as subprocesses (via Command::new(\"redis-server\") etc.). Each key toggles a specific service binary. Linux runners only for now.",
diff --git a/actions/environment-setup/scripts/parse-config.sh b/actions/environment-setup/scripts/parse-config.sh
index 9f156ec..cd3e1f3 100755
--- a/actions/environment-setup/scripts/parse-config.sh
+++ b/actions/environment-setup/scripts/parse-config.sh
@@ -96,6 +96,12 @@ fi
 out "has_config=true"
 echo "📖 Parsing $CONFIG_FILE..."
 
+# ------------------------------------------------------------------------------
+# Top-level knob: free disk space
+# ------------------------------------------------------------------------------
+FREE_DISK=$(yq_get '.free_disk_space' "false")
+out "free_disk_space=$FREE_DISK"
+
 # ------------------------------------------------------------------------------
 # Node.js
 # ------------------------------------------------------------------------------