ci(cua-driver): consolidate Linux Nix validation (conv2 6/7)

.github/workflows/ci-distro-compat-cua-driver.yml

@@ -18,7 +18,7 @@ name: "CI: cua-driver distro-compat matrix"
 #     built one. This is the only way to catch ABI mismatches because the NixOS
 #     CI builds its own binary against NixOS's own glibc.
 #   - Keep this fast and cheap: containers + --version/doctor only. Full GUI
-#     integration tests stay in nix-build.yml.
+#     behavior stays in the canonical Rust X11 and Wayland E2E workflows.
 #   - Non-blocking by default (continue-on-error: true) — the released binary
 #     may not exist yet on a fresh branch; the job is informational until the
 #     first linux release tag exists.
@@ -27,7 +27,8 @@ name: "CI: cua-driver distro-compat matrix"
 # Also runs on push to main and on workflow_dispatch so it works as a
 # post-release regression guard.
 #
-# Companion to nix-build.yml — does NOT replace it. See CUA-599.
+# Companion to the Rust desktop E2E workflows; it validates released binaries,
+# not source-built harness behavior.
 
 on:
   pull_request:

.github/workflows/ci-nix-linux.yml

@@ -1,23 +1,21 @@
 name: "CI: Nix Linux Rust source"
 
-# This is the automatic Nix lane. Desktop-heavy legacy checks live in
-# nix-build.yml and nix-wayland.yml and are maintainer-dispatched instead.
+# Nix owns reproducible Linux package and Rust-source builds. Interactive
+# desktop behavior is owned by the Rust E2E workflows.
 on:
   pull_request:
     paths:
       - "flake.nix"
       - "flake.lock"
-      - "nix/cua-driver/package.nix"
-      - "nix/cua-driver/tests/rust-unit.nix"
+      - "nix/cua-driver/**"
       - "libs/cua-driver/rust/**"
       - ".github/workflows/ci-nix-linux.yml"
   push:
     branches: [main]
     paths:
       - "flake.nix"
       - "flake.lock"
-      - "nix/cua-driver/package.nix"
-      - "nix/cua-driver/tests/rust-unit.nix"
+      - "nix/cua-driver/**"
       - "libs/cua-driver/rust/**"
       - ".github/workflows/ci-nix-linux.yml"
   workflow_dispatch:
@@ -31,15 +29,28 @@ concurrency:
 
 jobs:
   rust-source:
-    name: Nix Linux Rust source check
+    name: Nix / ${{ matrix.name }}
     runs-on: ubuntu-latest
-    timeout-minutes: 45
+    timeout-minutes: 60
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: compositor build
+            attribute: cua-compositor-build
+          - name: driver package
+            attribute: cua-driver-build
+          - name: Rust unit tests
+            attribute: cua-driver-linux-rust-unit
     steps:
       - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
       - name: Install Nix
         uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30
         with:
           extra_nix_config: |
             experimental-features = nix-command flakes
-      - name: Run source-built Rust check
-        run: nix build .#checks.x86_64-linux.cua-driver-linux-rust-unit --print-build-logs --show-trace
+      - name: Build ${{ matrix.name }}
+        run: >-
+          nix build
+          .#checks.x86_64-linux.${{ matrix.attribute }}
+          --no-link --print-build-logs --show-trace

.github/workflows/e2e-rust-linux-wayland.yml

@@ -14,6 +14,7 @@ on:
         default: sway
         options:
           - sway
+          - cua-compositor
       lane:
         description: "Diagnostic lane; canonical dispatches use all"
         required: false
@@ -80,6 +81,7 @@ jobs:
           ref: ${{ needs.source.outputs.sha }}
       - uses: dtolnay/rust-toolchain@stable
       - name: Install Sway and Rust build dependencies
+        if: inputs.environment == 'sway'
         shell: bash
         run: |
           sudo apt-get update
@@ -91,11 +93,23 @@ jobs:
             libxext-dev libdrm-dev libgbm-dev libwebkit2gtk-4.1-dev \
             libssl-dev libxdo-dev libayatana-appindicator3-dev librsvg2-dev \
             ffmpeg jq
+      - name: Install Nix for the custom compositor environment
+        if: inputs.environment == 'cua-compositor'
+        uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30
+        with:
+          extra_nix_config: |
+            experimental-features = nix-command flakes
       - name: Run complete native Wayland matrix
         shell: bash
         env:
           CUA_AT_SPI_BUS_LAUNCHER: /usr/libexec/at-spi-bus-launcher
-        run: scripts/ci/linux/run-rust-e2e-wayland.sh
+        run: |
+          if [[ "${{ inputs.environment }}" == "cua-compositor" ]]; then
+            nix develop .#cua-driver-inject-e2e \
+              -c scripts/ci/linux/run-rust-e2e-inject.sh
+          else
+            scripts/ci/linux/run-rust-e2e-wayland.sh
+          fi
       - name: Upload Wayland results
         if: always()
         uses: actions/upload-artifact@65c4c4a1ddee5b72f698fdd19549f0f0fb45cf08 # v4