diff --git a/scripts/check-changed.mjs b/scripts/check-changed.mjs
index 3414885d7f8..f9321ff0209 100644
--- a/scripts/check-changed.mjs
+++ b/scripts/check-changed.mjs
@@ -8,8 +8,7 @@ import {
 } from "./changed-lanes.mjs";
 import { booleanFlag, parseFlagArgs, stringFlag } from "./lib/arg-utils.mjs";
 import { printTimingSummary } from "./lib/check-timing-summary.mjs";
-
-const ROUTABLE_TEST_PATH_RE = /^(?:src|test|extensions|ui|packages|apps)(?:\/|$)/u;
+import { resolveChangedTestTargetPlan } from "./test-projects.test-support.mjs";
 
 export function createChangedCheckPlan(result) {
   const commands = [];
@@ -25,6 +24,7 @@ export function createChangedCheckPlan(result) {
     return {
       commands,
       testTargets: [],
+      runChangedTestsBroad: false,
       runFullTests: false,
       runExtensionTests: false,
       summary: "docs-only",
@@ -41,6 +41,7 @@ export function createChangedCheckPlan(result) {
     return {
       commands,
       testTargets: [],
+      runChangedTestsBroad: false,
       runFullTests: true,
       runExtensionTests: false,
       summary: "all",
@@ -82,10 +83,12 @@ export function createChangedCheckPlan(result) {
     add("pairing account guard", ["lint:auth:pairing-account-scope"]);
   }
 
-  const testTargets = result.paths.filter((changedPath) => ROUTABLE_TEST_PATH_RE.test(changedPath));
+  const testPlan = resolveChangedTestTargetPlan(result.paths);
+  const runChangedTestsBroad = testPlan.mode === "broad";
   return {
     commands,
-    testTargets,
+    testTargets: testPlan.targets,
+    runChangedTestsBroad,
     runFullTests: false,
     runExtensionTests: result.extensionImpactFromCore,
     summary: Object.entries(lanes)
@@ -118,6 +121,21 @@ export async function runChangedCheck(result, options = {}) {
       printSummary(timings, options);
       return status;
     }
+  } else if (plan.runChangedTestsBroad) {
+    const testArgs = options.explicitPaths
+      ? ["scripts/test-projects.mjs"]
+      : ["scripts/test-projects.mjs", "--changed", options.base ?? "origin/main"];
+    const status = await runNode(
+      {
+        name: options.explicitPaths ? "tests all" : "tests changed broad",
+        args: testArgs,
+      },
+      timings,
+    );
+    if (status !== 0) {
+      printSummary(timings, options);
+      return status;
+    }
   } else if (plan.testTargets.length > 0) {
     const status = await runNode(
       {
@@ -154,6 +172,9 @@ function printPlan(result, plan, options) {
   if (result.extensionImpactFromCore) {
     console.error(`${prefix} core contract changed; extension tests included`);
   }
+  if (plan.runChangedTestsBroad) {
+    console.error(`${prefix} broad changed tests included`);
+  }
   for (const reason of result.reasons) {
     console.error(`${prefix} ${reason}`);
   }
@@ -246,5 +267,8 @@ if (isDirectRun()) {
         ? listStagedChangedPaths()
         : listChangedPathsFromGit({ base: args.base, head: args.head });
   const result = detectChangedLanes(paths);
-  process.exitCode = await runChangedCheck(result, args);
+  process.exitCode = await runChangedCheck(result, {
+    ...args,
+    explicitPaths: args.paths.length > 0,
+  });
 }
diff --git a/scripts/test-projects.test-support.d.mts b/scripts/test-projects.test-support.d.mts
index 04fa5b5fe2d..e81d36d50a9 100644
--- a/scripts/test-projects.test-support.d.mts
+++ b/scripts/test-projects.test-support.d.mts
@@ -35,6 +35,11 @@ export function resolveChangedTargetArgs(
   listChangedPaths?: (baseRef: string, cwd: string) => string[],
 ): string[] | null;
 
+export function resolveChangedTestTargetPlan(changedPaths: string[]): {
+  mode: "none" | "broad" | "targets";
+  targets: string[];
+};
+
 export function listFullExtensionVitestProjectConfigs(): string[];
 
 export function createVitestRunSpecs(
diff --git a/scripts/test-projects.test-support.mjs b/scripts/test-projects.test-support.mjs
index 4c6e97828e1..896486e1e5d 100644
--- a/scripts/test-projects.test-support.mjs
+++ b/scripts/test-projects.test-support.mjs
@@ -168,9 +168,27 @@ const BROAD_CHANGED_RERUN_PATTERNS = [
   /^vitest(?:\..+)?\.(?:config\.ts|paths\.mjs)$/u,
   /^test\/vitest\/vitest\.(?:config|shared\.config|scoped-config|performance-config)\.ts$/u,
   /^test\/helpers\//u,
-  /^scripts\/run-vitest\.mjs$/u,
-  /^scripts\/test-projects(?:\.test-support)?\.mjs$/u,
 ];
+const TOOLING_SOURCE_TEST_TARGETS = new Map([
+  ["scripts/changed-lanes.mjs", ["test/scripts/changed-lanes.test.ts"]],
+  ["scripts/check-changed.mjs", ["test/scripts/changed-lanes.test.ts"]],
+  ["scripts/lib/vitest-local-scheduling.mjs", ["test/scripts/vitest-local-scheduling.test.ts"]],
+  [
+    "scripts/run-vitest.mjs",
+    ["test/scripts/test-projects.test.ts", "test/scripts/vitest-local-scheduling.test.ts"],
+  ],
+  ["scripts/test-projects.mjs", ["test/scripts/test-projects.test.ts"]],
+  ["scripts/test-projects.test-support.d.mts", ["test/scripts/test-projects.test.ts"]],
+  ["scripts/test-projects.test-support.mjs", ["test/scripts/test-projects.test.ts"]],
+]);
+const TOOLING_TEST_TARGETS = new Map([
+  ["test/scripts/changed-lanes.test.ts", ["test/scripts/changed-lanes.test.ts"]],
+  ["test/scripts/test-projects.test.ts", ["test/scripts/test-projects.test.ts"]],
+  [
+    "test/scripts/vitest-local-scheduling.test.ts",
+    ["test/scripts/vitest-local-scheduling.test.ts"],
+  ],
+]);
 const VITEST_CONFIG_TARGET_KIND_BY_PATH = new Map(
   Object.entries(VITEST_CONFIG_BY_KIND).map(([kind, config]) => [config, kind]),
 );
@@ -239,7 +257,29 @@ function isVitestConfigTargetForKind(kind, targetArg, cwd) {
 }
 
 function listChangedPathsFromGit(baseRef, cwd) {
-  return execFileSync("git", ["diff", "--name-only", `${baseRef}...HEAD`], {
+  return [
+    ...new Set([
+      ...runGitNameOnlyDiff(cwd, [`${baseRef}...HEAD`]),
+      ...runGitNameOnlyDiff(cwd, ["--cached", "--diff-filter=ACMR"]),
+      ...runGitNameOnlyDiff(cwd, ["--diff-filter=ACMR"]),
+      ...runGitLsFiles(cwd, ["--others", "--exclude-standard"]),
+    ]),
+  ].toSorted((left, right) => left.localeCompare(right));
+}
+
+function runGitNameOnlyDiff(cwd, extraArgs) {
+  return execFileSync("git", ["diff", "--name-only", ...extraArgs], {
+    cwd,
+    encoding: "utf8",
+    stdio: ["ignore", "pipe", "pipe"],
+  })
+    .split("\n")
+    .map((line) => normalizePathPattern(line.trim()))
+    .filter((line) => line.length > 0);
+}
+
+function runGitLsFiles(cwd, extraArgs) {
+  return execFileSync("git", ["ls-files", ...extraArgs], {
     cwd,
     encoding: "utf8",
     stdio: ["ignore", "pipe", "pipe"],
@@ -290,10 +330,45 @@ function shouldKeepBroadChangedRun(changedPaths) {
   );
 }
 
+function resolveToolingChangedTestTargets(changedPaths) {
+  const targets = [];
+  for (const changedPath of changedPaths) {
+    const testTargets =
+      TOOLING_SOURCE_TEST_TARGETS.get(changedPath) ?? TOOLING_TEST_TARGETS.get(changedPath);
+    if (!testTargets) {
+      return null;
+    }
+    targets.push(...testTargets);
+  }
+  return [...new Set(targets)];
+}
+
 function isRoutableChangedTarget(changedPath) {
   return /^(?:src|test|extensions|ui|packages)(?:\/|$)/u.test(changedPath);
 }
 
+export function resolveChangedTestTargetPlan(changedPaths) {
+  if (changedPaths.length === 0) {
+    return { mode: "none", targets: [] };
+  }
+  const toolingTargets = resolveToolingChangedTestTargets(changedPaths);
+  if (toolingTargets) {
+    return { mode: "targets", targets: toolingTargets };
+  }
+  if (shouldKeepBroadChangedRun(changedPaths)) {
+    return { mode: "broad", targets: [] };
+  }
+  const changedLanes = detectChangedLanes(changedPaths);
+  if (changedLanes.lanes.all) {
+    return { mode: "broad", targets: [] };
+  }
+  const targets = changedPaths.filter(isRoutableChangedTarget);
+  if (changedLanes.extensionImpactFromCore) {
+    targets.push("extensions");
+  }
+  return { mode: "targets", targets: [...new Set(targets)] };
+}
+
 export function listFullExtensionVitestProjectConfigs() {
   return (
     fullSuiteVitestShards.find((shard) => shard.config === FULL_EXTENSIONS_VITEST_CONFIG)
@@ -311,19 +386,11 @@ export function resolveChangedTargetArgs(
     return null;
   }
   const changedPaths = listChangedPaths(baseRef, cwd);
-  if (changedPaths.length === 0 || shouldKeepBroadChangedRun(changedPaths)) {
+  const plan = resolveChangedTestTargetPlan(changedPaths);
+  if (plan.mode === "broad") {
     return null;
   }
-  const changedLanes = detectChangedLanes(changedPaths);
-  if (changedLanes.lanes.all) {
-    return null;
-  }
-  const routablePaths = changedPaths.filter(isRoutableChangedTarget);
-  const targets = [...routablePaths];
-  if (changedLanes.extensionImpactFromCore) {
-    targets.push("extensions");
-  }
-  return [...new Set(targets)];
+  return plan.targets;
 }
 
 function classifyTarget(arg, cwd) {