ci: reduce node runner fanout

test/scripts/channel-contract-test-plan.test.ts

@@ -25,13 +25,11 @@ describe("scripts/lib/channel-contract-test-plan.mjs", () => {
         task: shard.task,
       })),
     ).toEqual(
-      ["registry", "core"].flatMap((family) =>
-        suffixes.map((suffix) => ({
-          checkName: `checks-fast-contracts-channels-${family}-${suffix}`,
-          runtime: "node",
-          task: "contracts-channels",
-        })),
-      ),
+      suffixes.map((suffix) => ({
+        checkName: `checks-fast-contracts-channels-${suffix}`,
+        runtime: "node",
+        task: "contracts-channels",
+      })),
     );
   });
 
@@ -45,13 +43,11 @@ describe("scripts/lib/channel-contract-test-plan.mjs", () => {
   });
 
   it("keeps registry-backed surface shards spread across checks", () => {
-    for (const shard of createChannelContractTestShards().filter((entry) =>
-      entry.checkName.includes("-registry-"),
-    )) {
+    for (const shard of createChannelContractTestShards()) {
       const surfaceRegistryFiles = shard.includePatterns.filter((pattern) =>
         pattern.includes("/surfaces-only.registry-backed-shard-"),
       );
-      expect(surfaceRegistryFiles.length).toBeLessThanOrEqual(3);
+      expect(surfaceRegistryFiles.length).toBeLessThanOrEqual(4);
     }
   });
 });

test/scripts/ci-node-test-plan.test.ts

@@ -25,6 +25,40 @@ function listTestFiles(rootDir: string): string[] {
 }
 
 describe("scripts/lib/ci-node-test-plan.mjs", () => {
+  it("combines the small core unit shards to reduce CI runner fanout", () => {
+    const coreUnitShards = createNodeTestShards()
+      .filter((shard) => shard.shardName.startsWith("core-unit-"))
+      .map((shard) => ({
+        configs: shard.configs,
+        requiresDist: shard.requiresDist,
+        shardName: shard.shardName,
+      }));
+
+    expect(coreUnitShards).toEqual([
+      {
+        configs: [
+          "test/vitest/vitest.unit-fast.config.ts",
+          "test/vitest/vitest.unit-support.config.ts",
+        ],
+        requiresDist: false,
+        shardName: "core-unit-fast-support",
+      },
+      {
+        configs: [
+          "test/vitest/vitest.unit-src.config.ts",
+          "test/vitest/vitest.unit-security.config.ts",
+        ],
+        requiresDist: false,
+        shardName: "core-unit-src-security",
+      },
+      {
+        configs: ["test/vitest/vitest.unit-ui.config.ts"],
+        requiresDist: false,
+        shardName: "core-unit-ui",
+      },
+    ]);
+  });
+
   it("names the node shard checks as core test lanes", () => {
     const shards = createNodeTestShards();