ci: exercise the PLATFORM_GUI depends knob in a linux64_platform_gui lane

The new lane builds depends with PLATFORM_GUI=1 (producing and hash-verifying the Platform CXX archive offline from vendored crates), then builds dash-qt against that prefix and runs the unit tests. The cache-sources producer generates and caches the platform-cxx vendored-crates archive, handing it to same-run consumers as an artifact on cache miss.

The --enable-platform-gui configure flag is added to this lane's BITCOIN_CONFIG by the Platform client library PR; until then the lane proves the depends knob and prefix link-compatibility. build.yml runs PR validation from the base branch (pull_request_target), so the lane first runs on push CI for this branch and takes effect for PRs after merge.

Author: PastaPastaPasta

.github/workflows/build-depends.yml

@@ -15,6 +15,11 @@ on:
         description: "Short hash of the CI base image manifest for cache busting"
         required: true
         type: string
+      rust-vendor-artifact:
+        description: "Artifact holding freshly generated Rust vendor archives"
+        required: false
+        type: string
+        default: ""
       runs-on:
         description: "Runner label to use (e.g., ubuntu-24.04 or ubuntu-24.04-arm)"
         required: true
@@ -144,6 +149,28 @@ jobs:
           key: depends-sources-${{ hashFiles('depends/packages/*') }}
           restore-keys: depends-sources-
 
+      - name: Restore Rust vendor sources
+        id: rust-vendor-cache
+        if: inputs.build-target == 'linux64_platform_gui'
+        uses: actions/cache/restore@v5
+        with:
+          path: depends/sources/platform-cxx-*-vendored.tar.gz
+          key: depends-rust-vendor-sources-${{ hashFiles('depends/Makefile', 'depends/funcs.mk', 'depends/packages/native_rust.mk', 'depends/packages/platform_cxx.mk', 'depends/patches/platform_cxx/cargo-config.toml') }}
+
+      - name: Download Rust vendor sources
+        if: inputs.build-target == 'linux64_platform_gui' && steps.rust-vendor-cache.outputs.cache-hit != 'true' && inputs.rust-vendor-artifact != ''
+        uses: actions/download-artifact@v8
+        with:
+          name: ${{ inputs.rust-vendor-artifact }}
+          path: depends/sources
+
+      - name: Check Rust vendor sources are present
+        if: inputs.build-target == 'linux64_platform_gui' && steps.rust-vendor-cache.outputs.cache-hit != 'true' && inputs.rust-vendor-artifact == ''
+        run: |
+          echo "::error::Rust vendor source cache missed and no same-run artifact was provided"
+          exit 1
+        shell: bash
+
       - name: Restore SDKs cache
         id: sdk-cache
         uses: actions/cache/restore@v5

.github/workflows/build.yml

@@ -165,6 +165,18 @@ jobs:
       base-image-digest: ${{ needs.check-skip.outputs.base-image-digest }}
       runs-on: ${{ needs.check-skip.outputs['runner-amd64'] }}
 
+  depends-linux64_platform_gui:
+    name: x86_64-pc-linux-gnu_platform_gui
+    uses: ./.github/workflows/build-depends.yml
+    needs: [check-skip, container, cache-sources]
+    if: ${{ vars.SKIP_LINUX64_PLATFORM_GUI == '' }}
+    with:
+      build-target: linux64_platform_gui
+      container-path: ${{ needs.container.outputs.path }}
+      base-image-digest: ${{ needs.check-skip.outputs.base-image-digest }}
+      rust-vendor-artifact: ${{ needs.cache-sources.outputs.rust-vendor-artifact }}
+      runs-on: ${{ needs.check-skip.outputs['runner-amd64'] }}
+
   depends-mac:
     name: x86_64-apple-darwin
     uses: ./.github/workflows/build-depends.yml
@@ -277,6 +289,20 @@ jobs:
       depends-artifact: ${{ needs.depends-linux64_nowallet.outputs.built-artifact }}
       runs-on: ${{ needs.check-skip.outputs['runner-amd64'] }}
 
+  src-linux64_platform_gui:
+    name: linux64_platform_gui-build
+    uses: ./.github/workflows/build-src.yml
+    needs: [check-skip, container, depends-linux64_platform_gui]
+    if: ${{ vars.SKIP_LINUX64_PLATFORM_GUI == '' }}
+    with:
+      build-target: linux64_platform_gui
+      container-path: ${{ needs.container.outputs.path }}
+      depends-key: ${{ needs.depends-linux64_platform_gui.outputs.key }}
+      depends-host: ${{ needs.depends-linux64_platform_gui.outputs.host }}
+      depends-dep-opts: ${{ needs.depends-linux64_platform_gui.outputs.dep-opts }}
+      depends-artifact: ${{ needs.depends-linux64_platform_gui.outputs.built-artifact }}
+      runs-on: ${{ needs.check-skip.outputs['runner-amd64'] }}
+
   src-linux64_sqlite:
     name: linux64_sqlite-build
     uses: ./.github/workflows/build-src.yml
@@ -372,6 +398,17 @@ jobs:
       container-path: ${{ needs.container-slim.outputs.path }}
       runs-on: ${{ needs.check-skip.outputs['runner-amd64'] }}
 
+  test-linux64_platform_gui:
+    name: linux64_platform_gui-test
+    uses: ./.github/workflows/test-src.yml
+    needs: [check-skip, container-slim, src-linux64_platform_gui, lint]
+    if: ${{ vars.SKIP_LINUX64_PLATFORM_GUI == '' }}
+    with:
+      bundle-key: ${{ needs.src-linux64_platform_gui.outputs.key }}
+      build-target: linux64_platform_gui
+      container-path: ${{ needs.container-slim.outputs.path }}
+      runs-on: ${{ needs.check-skip.outputs['runner-amd64'] }}
+
   test-linux64_sqlite:
     name: linux64_sqlite-test
     uses: ./.github/workflows/test-src.yml

.github/workflows/cache-depends-sources.yml

@@ -8,6 +8,10 @@ on:
         required: false
         type: string
         default: ubuntu-24.04-arm
+    outputs:
+      rust-vendor-artifact:
+        description: "Artifact holding freshly generated Rust vendor archives"
+        value: ${{ jobs.cache-sources.outputs.rust-vendor-artifact }}
   schedule:
     # Run daily at 6 AM UTC on the default branch to keep cache warm
     - cron: '0 6 * * *'
@@ -18,6 +22,8 @@ jobs:
     # Intentionally keep scheduled cache warming on GitHub-hosted ARM runners.
     # Blacksmith caches are expected to persist long enough without a warmup cron.
     runs-on: ${{ inputs.runs-on || 'ubuntu-24.04-arm' }}
+    outputs:
+      rust-vendor-artifact: ${{ steps.vendor-artifact.outputs.name }}
     steps:
       - name: Checkout code
         uses: actions/checkout@v6
@@ -35,6 +41,36 @@ jobs:
           restore-keys: depends-sources-
           lookup-only: true
 
+      - name: Cache Rust vendor sources
+        id: rust-vendor-cache
+        uses: actions/cache@v5
+        with:
+          path: depends/sources/platform-cxx-*-vendored.tar.gz
+          key: depends-rust-vendor-sources-${{ hashFiles('depends/Makefile', 'depends/funcs.mk', 'depends/packages/native_rust.mk', 'depends/packages/platform_cxx.mk', 'depends/patches/platform_cxx/cargo-config.toml') }}
+
       - name: Download sources
-        if: steps.cache-check.outputs.cache-hit != 'true'
-        run: make -C depends download
+        if: |
+          steps.cache-check.outputs.cache-hit != 'true' ||
+          steps.rust-vendor-cache.outputs.cache-hit != 'true'
+        run: |
+          make -C depends PLATFORM_GUI=1 download
+          make -C depends PLATFORM_GUI=1 vendor-platform_cxx-crates
+          # The cache producer normally runs on ARM, while the platform_gui
+          # consumer runs on x86_64. Native Rust is selected from the build
+          # architecture, so fetch the x86_64 compiler archive explicitly too.
+          make -C depends BUILD=x86_64-pc-linux-gnu PLATFORM_GUI=1 download-one
+
+      - name: Select Rust vendor artifact
+        id: vendor-artifact
+        if: github.event_name != 'schedule' && steps.rust-vendor-cache.outputs.cache-hit != 'true'
+        run: echo "name=depends-rust-vendor-sources-${{ github.run_id }}" >> "$GITHUB_OUTPUT"
+
+      - name: Upload Rust vendor sources
+        if: steps.vendor-artifact.outputs.name != ''
+        uses: actions/upload-artifact@v6
+        with:
+          name: ${{ steps.vendor-artifact.outputs.name }}
+          path: depends/sources/platform-cxx-*-vendored.tar.gz
+          compression-level: 0
+          retention-days: 1
+          overwrite: true

ci/dash/matrix.sh

@@ -28,6 +28,8 @@ elif [ "$BUILD_TARGET" = "linux64_multiprocess" ]; then
   source ./ci/test/00_setup_env_native_multiprocess.sh
 elif [ "$BUILD_TARGET" = "linux64_nowallet" ]; then
   source ./ci/test/00_setup_env_native_nowallet_libbitcoinkernel.sh
+elif [ "$BUILD_TARGET" = "linux64_platform_gui" ]; then
+  source ./ci/test/00_setup_env_native_platform_gui.sh
 elif [ "$BUILD_TARGET" = "linux64_sqlite" ]; then
   source ./ci/test/00_setup_env_native_sqlite.sh
 elif [ "$BUILD_TARGET" = "linux64_tsan" ]; then

ci/test/00_setup_env_native_platform_gui.sh

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+#
+# Copyright (c) 2026 The Dash Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+export LC_ALL=C.UTF-8
+
+# Builds depends with PLATFORM_GUI=1 so mbedtls and the Platform-owned CXX
+# binding archive (libdash_platform_cxx.a, built offline from vendored crates)
+# are produced, hash-verified and installed into the depends prefix, then
+# builds dash-qt against that prefix. The --enable-platform-gui configure flag
+# and the platform_* unit-test suites arrive with the Platform client library
+# and are added to BITCOIN_CONFIG there; until then this lane proves the
+# depends knob end to end and that the enriched prefix stays link-compatible.
+# Functional tests are skipped: there is no dashd-only surface to drive.
+export CONTAINER_NAME=ci_native_platform_gui
+export HOST=x86_64-pc-linux-gnu
+export PACKAGES="python3-zmq qtbase5-dev qttools5-dev-tools libdbus-1-dev libharfbuzz-dev"
+export DEP_OPTS="PLATFORM_GUI=1"
+export RUN_UNIT_TESTS="true"
+export RUN_UNIT_TESTS_SEQUENTIAL="false"
+export RUN_FUNCTIONAL_TESTS="false"
+export GOAL="install"
+export BITCOIN_CONFIG="--with-gui=qt5 --enable-zmq --with-libs=no --enable-reduce-exports LDFLAGS=-static-libstdc++"