fix(ci): skip platforms without selected artifacts

build_tools/github_actions/configure_multi_arch_ci.py

@@ -1800,7 +1800,8 @@ def expand_build_configs(
     """Build a BuildConfig for each platform that supports the variant.
 
     Returns BuildConfigs with a BuildConfig per platform, or None for
-    platforms where the variant isn't available or no families match.
+    platforms where the variant isn't available, no families match, or no
+    artifacts will be built or reused.
     """
     all_families = get_all_families_for_trigger_types(
         ["presubmit", "postsubmit", "nightly"]
@@ -1834,6 +1835,15 @@ def expand_build_configs(
     linux_config: BuildConfig | None = None
     windows_config: BuildConfig | None = None
 
+    # Prebuilt stages still supply artifacts; only SKIP removes a stage's work.
+    topology = get_topology()
+    active_artifacts = [
+        topology.artifacts[name]
+        for stage in topology.get_build_stages()
+        if jobs.build_rocm.stage_decisions.get(stage.name) != JobAction.SKIP
+        for name in topology.get_produced_artifacts(stage.name)
+    ]
+
     for platform, families, build_only, test_only in [
         (
             "linux",
@@ -1848,6 +1858,13 @@ def expand_build_configs(
             targets.windows_test_only_families,
         ),
     ]:
+        if not any(
+            artifact.platform in (None, platform)
+            and platform not in artifact.disable_platforms
+            for artifact in active_artifacts
+        ):
+            print(f"  Platform {platform} has no artifacts to build or reuse, skipping")
+            continue
         variant_config = all_build_variants.get(platform, {}).get(build_variant)
         if not variant_config:
             print(

build_tools/github_actions/github_actions_api.py

@@ -477,7 +477,7 @@ def gha_append_step_summary(summary: str, mirror_to_job_file: bool = True):
     # Use double newlines to split sections in markdown.
     block = summary + "\n\n"
 
-    with open(step_summary_file, "a") as f:
+    with open(step_summary_file, "a", encoding="utf-8") as f:
         # Use double newlines to split sections in markdown.
         f.write(block)
 

build_tools/github_actions/tests/configure_multi_arch_ci_test.py

@@ -2202,7 +2202,7 @@ def _write_outputs(self, outputs: cm.CIOutputs) -> tuple[str, str]:
 
             return (
                 github_output.read_text(),
-                step_summary.read_text(),
+                step_summary.read_text(encoding="utf-8"),
             )
 
     def test_running_ci(self):
@@ -2225,6 +2225,54 @@ def test_skipped_ci(self):
         self.assertIn("enable_build_jobs=false", github_output)
         self.assertTrue(step_summary.startswith("## Multi-Arch CI Configuration"))
 
+    def test_platform_outputs_follow_selected_stages(self):
+        """Linux-only stages must not launch Windows artifact consumers.
+
+        Prebuilt stages count as work, but only inside the build allowlist.
+        Exercise the full setup pipeline and the outputs used by workflow gates.
+        """
+        cases = [
+            (["emulation"], "", False),
+            (["emulation"], "emulation", False),
+            (["emulation"], "compiler-runtime", False),
+            (["compiler-runtime"], "", True),
+            (["compiler-runtime"], "compiler-runtime", True),
+            ([], "", True),
+            ([], "all", True),
+        ]
+        for stages, prebuilt, expect_windows in cases:
+            with (
+                self.subTest(stages=stages, prebuilt=prebuilt),
+                patch.dict(os.environ, {"STAGE_REUSE_MODE": "dry-run"}),
+            ):
+                inputs = cm.CIInputs(
+                    run_id="12345",
+                    event_name="pull_request",
+                    commit_ref="feature",
+                    base_ref="HEAD^",
+                    build_variant="release",
+                    linux_amdgpu_families=["gfx94x"],
+                    windows_amdgpu_families=["gfx110x"],
+                    build_stages=stages,
+                    prebuilt_stages=prebuilt,
+                    baseline_run_id="123" if prebuilt else "",
+                )
+                outputs = cm.configure(inputs, cm.GitContext.empty())
+                github_output, _ = self._write_outputs(outputs)
+                values = dict(line.split("=", 1) for line in github_output.splitlines())
+                linux = json.loads(values["linux_build_config"])
+                self.assertEqual(linux["dist_amdgpu_families"], "gfx94X-dcgpu")
+                if expect_windows:
+                    windows = json.loads(values["windows_build_config"])
+                    self.assertEqual(windows["dist_amdgpu_families"], "gfx110X-all")
+                    self.assertEqual(linux["windows_amdgpu_families"], "gfx110X-all")
+                    if prebuilt:
+                        self.assertIn("compiler-runtime", windows["prebuilt_stages"])
+                        self.assertEqual(windows["baseline_run_id"], "123")
+                else:
+                    self.assertEqual(values["windows_build_config"], "")
+                    self.assertEqual(linux["windows_amdgpu_families"], "")
+
 
 # ---------------------------------------------------------------------------
 # End-to-end: configure() pipeline

build_tools/github_actions/tests/github_actions_api_test.py

@@ -1013,7 +1013,7 @@ def test_append_writes_both_step_summary_and_mirror(self):
         self.assertEqual(mirror.read_text(encoding="utf-8"), expected)
 
     def test_append_multiline_summary(self):
-        summary = "### Heading\n\n- bullet a\n- bullet b\n\n| col |\n| --- |"
+        summary = "### 📋 Heading\n\n- bullet a\n- bullet b\n\n| col |\n| --- |"
         with mock.patch.dict(os.environ, self.env, clear=False):
             gha_append_step_summary(summary)