diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 49a00fcaad0..86398f8afac 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -306,7 +306,7 @@ repos:
         entry: npm run source-shape:check
         language: system
         pass_filenames: false
-        files: ^(.+\.(test|spec)\.(js|ts|mjs|mts|cjs|cts)|scripts/find-source-shape-tests\.ts|ci/source-shape-test-budget\.json)$
+        files: ^(.+\.(test|spec)\.(js|ts|mjs|mts|cjs|cts)|scripts/find-source-shape-tests\.mts|ci/source-shape-test-budget\.json)$
         priority: 20
 
       - id: test-file-size-budget
@@ -314,7 +314,7 @@ repos:
         entry: npm run test-size:check
         language: system
         pass_filenames: false
-        files: ^(test/|src/.*\.(test|spec)\.(ts|js|mts|mjs|cts|cjs)$|nemoclaw/src/.*\.(test|spec)\.(ts|js|mts|mjs|cts|cjs)$|scripts/check-test-file-size-budget\.ts$|ci/test-file-size-budget\.json$)
+        files: ^(test/|src/.*\.(test|spec)\.(ts|js|mts|mjs|cts|cjs)$|nemoclaw/src/.*\.(test|spec)\.(ts|js|mts|mjs|cts|cjs)$|scripts/check-test-file-size-budget\.mts$|ci/test-file-size-budget\.json$)
         priority: 20
 
       - id: test-skills-yaml
diff --git a/package.json b/package.json
index 5544c3a5789..c8b2029d677 100644
--- a/package.json
+++ b/package.json
@@ -32,8 +32,8 @@
     "test:diagnose:leaks": "vitest run --project cli --project plugin --project e2e-support --detectAsyncLeaks --coverage=false --reporter=default --reporter=hanging-process",
     "test:integration": "npm run clean:cli && npm run build:cli && vitest run --project integration --project installer-integration",
     "test:package": "npm run clean:cli && npm --prefix nemoclaw run clean && npm run build:cli && npm --prefix nemoclaw run build && vitest run --project package-contract",
-    "test:coverage:cli": "npm run clean:cli && npm run build:cli && tsx scripts/check-dist-sourcemaps.ts dist && vitest run --project cli --project integration --coverage --coverage.reporter=text-summary --coverage.reporter=json-summary --coverage.reportsDirectory=coverage/cli --coverage.include=\"bin/**/*.js\" --coverage.include=\"src/**/*.ts\" --coverage.exclude=\"test/**/*.js\" --coverage.exclude=\"test/**/*.ts\" && tsx scripts/check-coverage-ratchet.ts coverage/cli/coverage-summary.json ci/coverage-threshold-cli.json \"CLI coverage\"",
-    "test:coverage:plugin": "vitest run --project plugin --coverage --coverage.reporter=text-summary --coverage.reporter=json-summary --coverage.reportsDirectory=coverage/plugin --coverage.include=\"nemoclaw/src/**/*.ts\" --coverage.include=\"nemoclaw/src/**/*.cts\" --coverage.exclude=\"**/*.test.ts\" && tsx scripts/check-coverage-ratchet.ts coverage/plugin/coverage-summary.json ci/coverage-threshold-plugin.json \"Plugin coverage\"",
+    "test:coverage:cli": "npm run clean:cli && npm run build:cli && tsx scripts/check-dist-sourcemaps.mts dist && vitest run --project cli --project integration --coverage --coverage.reporter=text-summary --coverage.reporter=json-summary --coverage.reportsDirectory=coverage/cli --coverage.include=\"bin/**/*.js\" --coverage.include=\"src/**/*.ts\" --coverage.exclude=\"test/**/*.js\" --coverage.exclude=\"test/**/*.ts\" && tsx scripts/check-coverage-ratchet.mts coverage/cli/coverage-summary.json ci/coverage-threshold-cli.json \"CLI coverage\"",
+    "test:coverage:plugin": "vitest run --project plugin --coverage --coverage.reporter=text-summary --coverage.reporter=json-summary --coverage.reportsDirectory=coverage/plugin --coverage.include=\"nemoclaw/src/**/*.ts\" --coverage.include=\"nemoclaw/src/**/*.cts\" --coverage.exclude=\"**/*.test.ts\" && tsx scripts/check-coverage-ratchet.mts coverage/plugin/coverage-summary.json ci/coverage-threshold-plugin.json \"Plugin coverage\"",
     "test:live-e2e": "npm run clean:cli && npm run build:cli && NEMOCLAW_RUN_LIVE_E2E=1 vitest run --project e2e-live",
     "test:imports:check": "tsx scripts/checks/no-test-dist-imports.ts",
     "test:projects:check": "tsx scripts/checks/vitest-project-overlap.ts",
@@ -54,11 +54,11 @@
     "clean:cli": "node -e \"require('node:fs').rmSync('dist', { recursive: true, force: true })\"",
     "typecheck:cli": "tsc -p tsconfig.cli.json",
     "validate:configs": "tsx scripts/validate-configs.mts",
-    "type-safety:hotspots": "tsx scripts/type-safety-hotspots.ts",
-    "source-shape:scan": "tsx scripts/find-source-shape-tests.ts --metrics",
-    "source-shape:check": "tsx scripts/find-source-shape-tests.ts --check",
-    "test-size:check": "tsx scripts/check-test-file-size-budget.ts",
-    "test-conditionals:scan": "tsx scripts/find-test-conditionals.ts",
+    "type-safety:hotspots": "tsx scripts/type-safety-hotspots.mts",
+    "source-shape:scan": "tsx scripts/find-source-shape-tests.mts --metrics",
+    "source-shape:check": "tsx scripts/find-source-shape-tests.mts --check",
+    "test-size:check": "tsx scripts/check-test-file-size-budget.mts",
+    "test-conditionals:scan": "tsx scripts/find-test-conditionals.mts",
     "bump:version": "tsx scripts/bump-version.mts",
     "release:plan": "tsx scripts/release-plan.mts",
     "release:cut": "bash scripts/release-cut-tag.sh",
diff --git a/scripts/check-coverage-ratchet.ts b/scripts/check-coverage-ratchet.mts
similarity index 97%
rename from scripts/check-coverage-ratchet.ts
rename to scripts/check-coverage-ratchet.mts
index a28b3aacaa9..a92a6144a7d 100755
--- a/scripts/check-coverage-ratchet.ts
+++ b/scripts/check-coverage-ratchet.mts
@@ -69,7 +69,7 @@ function main(): void {
   const [summaryPath, thresholdPath, label = "coverage"] = process.argv.slice(2);
   if (!summaryPath || !thresholdPath) {
     throw new Error(
-      "Usage: coverage-ratchet.ts <coverage-summary.json> <coverage-threshold.json> [label]",
+      "Usage: check-coverage-ratchet.mts <coverage-summary.json> <coverage-threshold.json> [label]",
     );
   }
 
diff --git a/scripts/check-dist-sourcemaps.ts b/scripts/check-dist-sourcemaps.mts
similarity index 95%
rename from scripts/check-dist-sourcemaps.ts
rename to scripts/check-dist-sourcemaps.mts
index 3b7dbf22f7d..17634aefeca 100644
--- a/scripts/check-dist-sourcemaps.ts
+++ b/scripts/check-dist-sourcemaps.mts
@@ -3,6 +3,7 @@
 
 import fs from "node:fs";
 import path from "node:path";
+import { fileURLToPath } from "node:url";
 
 type SourceMap = {
   sources?: unknown;
@@ -76,6 +77,6 @@ function main(): void {
   process.exit(1);
 }
 
-if (require.main === module) {
+if (fileURLToPath(import.meta.url) === path.resolve(process.argv[1] ?? "")) {
   main();
 }
diff --git a/scripts/check-test-file-size-budget.ts b/scripts/check-test-file-size-budget.mts
similarity index 100%
rename from scripts/check-test-file-size-budget.ts
rename to scripts/check-test-file-size-budget.mts
diff --git a/scripts/find-source-shape-tests.ts b/scripts/find-source-shape-tests.mts
similarity index 99%
rename from scripts/find-source-shape-tests.ts
rename to scripts/find-source-shape-tests.mts
index 54521b41402..bfbb40f4f0e 100755
--- a/scripts/find-source-shape-tests.ts
+++ b/scripts/find-source-shape-tests.mts
@@ -2109,7 +2109,7 @@ function isDirectInvocation(): boolean {
   const invoked = process.argv[1];
   return Boolean(
     invoked &&
-      (import.meta.url === `file://${invoked}` || invoked.endsWith("find-source-shape-tests.ts")),
+      (import.meta.url === `file://${invoked}` || invoked.endsWith("find-source-shape-tests.mts")),
   );
 }
 
diff --git a/scripts/find-test-conditionals.ts b/scripts/find-test-conditionals.mts
similarity index 99%
rename from scripts/find-test-conditionals.ts
rename to scripts/find-test-conditionals.mts
index f817387b83b..285756b9493 100755
--- a/scripts/find-test-conditionals.ts
+++ b/scripts/find-test-conditionals.mts
@@ -557,7 +557,7 @@ function parseArgs(argv: readonly string[]): CliOptions {
       roots.push(argv[++index] ?? "");
     } else if (arg === "--help" || arg === "-h") {
       console.log(
-        `Usage: tsx scripts/find-test-conditionals.ts [--top N] [--min-score N] [--root PATH] [--json]\n\nScans test/spec files under test, src, and nemoclaw/src by default.`,
+        `Usage: tsx scripts/find-test-conditionals.mts [--top N] [--min-score N] [--root PATH] [--json]\n\nScans test/spec files under test, src, and nemoclaw/src by default.`,
       );
       process.exit(0);
     } else {
diff --git a/scripts/list-command-helper-uses.ts b/scripts/list-command-helper-uses.mts
similarity index 97%
rename from scripts/list-command-helper-uses.ts
rename to scripts/list-command-helper-uses.mts
index e839aefcc78..ba0c6a939a1 100644
--- a/scripts/list-command-helper-uses.ts
+++ b/scripts/list-command-helper-uses.mts
@@ -168,13 +168,13 @@ function parseArgs(argv: string[]): Options {
 
 function printHelp(): void {
   console.log(
-    "Usage: tsx scripts/list-command-helper-uses.ts [--root <dir>] [--names run,runInteractive,...] [--include-tests] [--list-calls] [--markdown] [--json] [path ...]\n\n" +
+    "Usage: tsx scripts/list-command-helper-uses.mts [--root <dir>] [--names run,runInteractive,...] [--include-tests] [--list-calls] [--markdown] [--json] [path ...]\n\n" +
       "Lists AST-level callsites and assignments for command helper names such as run(), runInteractive(), runCapture(), runShell(), execFileSync(), spawnSync(), and runCommand(). By default it excludes test files and groups results by inferred command head.\n\n" +
       "Examples:\n" +
-      "  tsx scripts/list-command-helper-uses.ts\n" +
-      "  tsx scripts/list-command-helper-uses.ts --markdown src\n" +
-      "  tsx scripts/list-command-helper-uses.ts --include-tests --list-calls --json src test\n" +
-      "  tsx scripts/list-command-helper-uses.ts --names run,runInteractive src test\n",
+      "  tsx scripts/list-command-helper-uses.mts\n" +
+      "  tsx scripts/list-command-helper-uses.mts --markdown src\n" +
+      "  tsx scripts/list-command-helper-uses.mts --include-tests --list-calls --json src test\n" +
+      "  tsx scripts/list-command-helper-uses.mts --names run,runInteractive src test\n",
   );
 }
 
diff --git a/scripts/type-safety-hotspots.ts b/scripts/type-safety-hotspots.mts
similarity index 100%
rename from scripts/type-safety-hotspots.ts
rename to scripts/type-safety-hotspots.mts
diff --git a/test/codebase-growth-guardrails-conditionals.test.ts b/test/codebase-growth-guardrails-conditionals.test.ts
index ceb9eaae4e9..2b84c905f81 100644
--- a/test/codebase-growth-guardrails-conditionals.test.ts
+++ b/test/codebase-growth-guardrails-conditionals.test.ts
@@ -8,7 +8,7 @@ import path from "node:path";
 
 import { describe, expect, it } from "vitest";
 
-import { scanTextForTestConditionals } from "../scripts/find-test-conditionals";
+import { scanTextForTestConditionals } from "../scripts/find-test-conditionals.mts";
 
 const WORKFLOW_PATH = ".github/workflows/codebase-growth-guardrails.yaml";
 const STEP_NAME = "Require changed test files not to add if statements";
diff --git a/test/coverage-ratchet.test.ts b/test/coverage-ratchet.test.ts
index c63097708c5..1b343427a1c 100644
--- a/test/coverage-ratchet.test.ts
+++ b/test/coverage-ratchet.test.ts
@@ -7,7 +7,7 @@ import { tmpdir } from "node:os";
 import { join, relative } from "node:path";
 import { describe, expect, it } from "vitest";
 
-import { findCoverageFailures } from "../scripts/check-coverage-ratchet";
+import { findCoverageFailures } from "../scripts/check-coverage-ratchet.mts";
 
 const thresholds = {
   lines: 71.2,
@@ -51,7 +51,7 @@ describe("coverage ratchet", () => {
         [
           "--import",
           "tsx",
-          "scripts/check-coverage-ratchet.ts",
+          "scripts/check-coverage-ratchet.mts",
           relative(process.cwd(), summaryPath),
           relative(process.cwd(), thresholdPath),
           "Test coverage",
@@ -66,4 +66,17 @@ describe("coverage ratchet", () => {
       rmSync(directory, { force: true, recursive: true });
     }
   });
+
+  it("reports the .mts usage path when required arguments are missing (#6922)", () => {
+    const result = spawnSync(
+      process.execPath,
+      ["--import", "tsx", "scripts/check-coverage-ratchet.mts"],
+      { cwd: process.cwd(), encoding: "utf8" },
+    );
+
+    expect(result.status).toBe(1);
+    expect(result.stderr).toContain(
+      "Usage: check-coverage-ratchet.mts <coverage-summary.json> <coverage-threshold.json> [label]",
+    );
+  });
 });
diff --git a/test/dist-sourcemaps.test.ts b/test/dist-sourcemaps.test.ts
index 938d45f8a46..bf957fbd6ee 100644
--- a/test/dist-sourcemaps.test.ts
+++ b/test/dist-sourcemaps.test.ts
@@ -1,35 +1,103 @@
 // SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
 
+import { spawnSync } from "node:child_process";
 import fs from "node:fs";
 import os from "node:os";
 import path from "node:path";
+import { pathToFileURL } from "node:url";
 
 import { describe, expect, it } from "vitest";
 
-import { findMissingDistSourcemapSources } from "../scripts/check-dist-sourcemaps";
+import { findMissingDistSourcemapSources } from "../scripts/check-dist-sourcemaps.mts";
+
+function writeCleanFixtureDist(root: string): string {
+  const distLib = path.join(root, "dist", "lib");
+  const srcLib = path.join(root, "src", "lib");
+  fs.mkdirSync(distLib, { recursive: true });
+  fs.mkdirSync(srcLib, { recursive: true });
+  fs.writeFileSync(path.join(srcLib, "present.ts"), "export {};\n");
+  fs.writeFileSync(
+    path.join(distLib, "present.js.map"),
+    JSON.stringify({ version: 3, sources: ["../../src/lib/present.ts"], mappings: "" }),
+  );
+  return path.join(root, "dist");
+}
+
+function writeStaleFixtureDist(root: string): string {
+  const distDir = writeCleanFixtureDist(root);
+  fs.writeFileSync(
+    path.join(distDir, "lib", "missing.js.map"),
+    JSON.stringify({ version: 3, sources: ["../../src/lib/missing.ts"], mappings: "" }),
+  );
+  return distDir;
+}
 
 describe("dist sourcemap checks", () => {
   it("reports JavaScript sourcemaps pointing at missing source files", () => {
     const root = fs.mkdtempSync(path.join(os.tmpdir(), "nemoclaw-sourcemap-check-"));
-    const distLib = path.join(root, "dist", "lib");
-    const srcLib = path.join(root, "src", "lib");
-    fs.mkdirSync(distLib, { recursive: true });
-    fs.mkdirSync(srcLib, { recursive: true });
-    fs.writeFileSync(path.join(srcLib, "present.ts"), "export {};\n");
-    fs.writeFileSync(
-      path.join(distLib, "present.js.map"),
-      JSON.stringify({ version: 3, sources: ["../../src/lib/present.ts"], mappings: "" }),
+    const distDir = writeStaleFixtureDist(root);
+
+    expect(findMissingDistSourcemapSources(distDir)).toEqual([
+      `${path.join(distDir, "lib", "missing.js.map")} -> ../../src/lib/missing.ts`,
+    ]);
+
+    fs.rmSync(root, { recursive: true, force: true });
+  });
+
+  it("invoking the .mts entrypoint directly exits 0 for a clean dist directory", () => {
+    const root = fs.mkdtempSync(path.join(os.tmpdir(), "nemoclaw-sourcemap-cli-clean-"));
+    const distDir = writeCleanFixtureDist(root);
+
+    const result = spawnSync(
+      process.execPath,
+      ["--import", "tsx", "scripts/check-dist-sourcemaps.mts", distDir],
+      { cwd: process.cwd(), encoding: "utf8" },
     );
-    fs.writeFileSync(
-      path.join(distLib, "missing.js.map"),
-      JSON.stringify({ version: 3, sources: ["../../src/lib/missing.ts"], mappings: "" }),
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toContain(
+      `All JavaScript sourcemaps in ${distDir} reference existing sources.`,
     );
 
-    expect(findMissingDistSourcemapSources(path.join(root, "dist"))).toEqual([
-      `${path.join(distLib, "missing.js.map")} -> ../../src/lib/missing.ts`,
-    ]);
+    fs.rmSync(root, { recursive: true, force: true });
+  });
+
+  it("invoking the .mts entrypoint directly exits 1 and reports stale sources", () => {
+    const root = fs.mkdtempSync(path.join(os.tmpdir(), "nemoclaw-sourcemap-cli-stale-"));
+    const distDir = writeStaleFixtureDist(root);
+
+    const result = spawnSync(
+      process.execPath,
+      ["--import", "tsx", "scripts/check-dist-sourcemaps.mts", distDir],
+      { cwd: process.cwd(), encoding: "utf8" },
+    );
+
+    expect(result.status).toBe(1);
+    expect(result.stderr).toContain(`Stale JavaScript sourcemap sources found in ${distDir}:`);
+    expect(result.stderr).toContain(
+      `${path.join(distDir, "lib", "missing.js.map")} -> ../../src/lib/missing.ts`,
+    );
 
     fs.rmSync(root, { recursive: true, force: true });
   });
+
+  it("importing the .mts entrypoint does not run its CLI main", () => {
+    const scriptUrl = pathToFileURL(path.resolve("scripts/check-dist-sourcemaps.mts")).href;
+    const result = spawnSync(
+      process.execPath,
+      [
+        "--import",
+        "tsx",
+        "-e",
+        `import(${JSON.stringify(scriptUrl)}).then(() => { console.log("IMPORT_ONLY_OK"); });`,
+      ],
+      { cwd: process.cwd(), encoding: "utf8" },
+    );
+
+    expect(result.status).toBe(0);
+    expect(result.stdout.trim()).toBe("IMPORT_ONLY_OK");
+    expect(result.stdout).not.toContain("reference existing sources");
+    expect(result.stdout).not.toContain("Stale JavaScript sourcemap sources found");
+  });
 });
diff --git a/test/docker-abstraction-guard.test.ts b/test/docker-abstraction-guard.test.ts
index 98fe989ab7f..56a44f895a1 100644
--- a/test/docker-abstraction-guard.test.ts
+++ b/test/docker-abstraction-guard.test.ts
@@ -8,7 +8,7 @@ import { describe, expect, it } from "vitest";
 
 const REPO_ROOT = path.join(import.meta.dirname, "..");
 const TSX = path.join(REPO_ROOT, "node_modules", ".bin", "tsx");
-const INVENTORY_SCRIPT = path.join(REPO_ROOT, "scripts", "list-command-helper-uses.ts");
+const INVENTORY_SCRIPT = path.join(REPO_ROOT, "scripts", "list-command-helper-uses.mts");
 const DOCKER_ABSTRACTION_PREFIX = "src/lib/adapters/docker/";
 
 type CommandUse = {
diff --git a/test/list-command-helper-uses.test.ts b/test/list-command-helper-uses.test.ts
index 3a82f78fb56..fe3c69ca2f2 100644
--- a/test/list-command-helper-uses.test.ts
+++ b/test/list-command-helper-uses.test.ts
@@ -10,7 +10,7 @@ import { describe, expect, it } from "vitest";
 
 const REPO_ROOT = path.join(import.meta.dirname, "..");
 const TSX = path.join(REPO_ROOT, "node_modules", ".bin", "tsx");
-const SCRIPT = path.join(REPO_ROOT, "scripts", "list-command-helper-uses.ts");
+const SCRIPT = path.join(REPO_ROOT, "scripts", "list-command-helper-uses.mts");
 
 type HelperMatch = {
   filePath: string;
diff --git a/test/pr-workflow-contract.test.ts b/test/pr-workflow-contract.test.ts
index f6d265634b3..0af5ac9d774 100644
--- a/test/pr-workflow-contract.test.ts
+++ b/test/pr-workflow-contract.test.ts
@@ -569,7 +569,7 @@ describe("pull request and main workflow contracts", () => {
       "test/example.test.ts",
       "src/lib/example.spec.ts",
       "nemoclaw/src/example.test.ts",
-      "scripts/find-source-shape-tests.ts",
+      "scripts/find-source-shape-tests.mts",
       "ci/source-shape-test-budget.json",
     ]) {
       expect(files.test(path), path).toBe(true);
@@ -657,7 +657,7 @@ describe("pull request and main workflow contracts", () => {
     );
     expect(cliCoverageCalls[4]).toEqual([
       "tsx",
-      "scripts/check-coverage-ratchet.ts",
+      "scripts/check-coverage-ratchet.mts",
       "coverage/cli/coverage-summary.json",
       "ci/coverage-threshold-cli.json",
       "CLI coverage",
@@ -672,7 +672,7 @@ describe("pull request and main workflow contracts", () => {
     );
     expect(pluginCoverageCalls[1]).toEqual([
       "tsx",
-      "scripts/check-coverage-ratchet.ts",
+      "scripts/check-coverage-ratchet.mts",
       "coverage/plugin/coverage-summary.json",
       "ci/coverage-threshold-plugin.json",
       "Plugin coverage",
diff --git a/test/source-shape-scanner.test.ts b/test/source-shape-scanner.test.ts
index 410b0893ea8..97e673c4691 100644
--- a/test/source-shape-scanner.test.ts
+++ b/test/source-shape-scanner.test.ts
@@ -1,6 +1,10 @@
 // SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
 
+import { spawnSync } from "node:child_process";
+import path from "node:path";
+import { pathToFileURL } from "node:url";
+
 import { describe, expect, it } from "vitest";
 
 import {
@@ -8,7 +12,7 @@ import {
   scanTextForTest,
   scanTextForTestReport,
   sourceShapeSummary,
-} from "../scripts/find-source-shape-tests";
+} from "../scripts/find-source-shape-tests.mts";
 
 function detectedCaseNames(source: string): string[] {
   return scanTextForTest("test/virtual-source-shape.test.ts", source).map((entry) => entry.name);
@@ -666,3 +670,48 @@ describe("source-shape scanner", () => {
     ).toEqual([expect.stringContaining("duplicate source-shape exception identity")]);
   });
 });
+
+describe("source-shape scanner CLI entrypoint", () => {
+  function runCli(...args: string[]): { status: number | null; stdout: string; stderr: string } {
+    const result = spawnSync(
+      process.execPath,
+      ["--import", "tsx", "scripts/find-source-shape-tests.mts", ...args],
+      { cwd: process.cwd(), encoding: "utf8" },
+    );
+    return { status: result.status, stdout: result.stdout, stderr: result.stderr };
+  }
+
+  it("invoking the .mts entrypoint with --check prints the human report, metrics, and preserves the budget exit status", () => {
+    const { status, stdout } = runCli("--check");
+    expect(status).toBe(0);
+    expect(stdout).toMatch(
+      /No source-shape tests detected\.|Detected \d+ source-shape test cases:/,
+    );
+    expect(stdout).toContain("METRIC source_shape_cases=");
+  }, 90_000);
+
+  it("invoking the .mts entrypoint with --json prints a parsable report and exits 0", () => {
+    const { status, stdout } = runCli("--json");
+    expect(status).toBe(0);
+    const report = JSON.parse(stdout) as { summary: { source_shape_cases: number } };
+    expect(typeof report.summary.source_shape_cases).toBe("number");
+  }, 90_000);
+
+  it("importing the .mts entrypoint does not run its CLI main", () => {
+    const scriptUrl = pathToFileURL(path.resolve("scripts/find-source-shape-tests.mts")).href;
+    const result = spawnSync(
+      process.execPath,
+      [
+        "--import",
+        "tsx",
+        "-e",
+        `import(${JSON.stringify(scriptUrl)}).then(() => { console.log("IMPORT_ONLY_OK"); });`,
+      ],
+      { cwd: process.cwd(), encoding: "utf8" },
+    );
+
+    expect(result.status).toBe(0);
+    expect(result.stdout.trim()).toBe("IMPORT_ONLY_OK");
+    expect(result.stdout).not.toContain("METRIC source_shape_cases=");
+  });
+});
diff --git a/test/test-conditionals-scanner.test.ts b/test/test-conditionals-scanner.test.ts
index 665ca8d7876..0ddc5012bd1 100644
--- a/test/test-conditionals-scanner.test.ts
+++ b/test/test-conditionals-scanner.test.ts
@@ -3,7 +3,7 @@
 
 import { describe, expect, it } from "vitest";
 
-import { scanTextForTestConditionals } from "../scripts/find-test-conditionals";
+import { scanTextForTestConditionals } from "../scripts/find-test-conditionals.mts";
 
 describe("test conditional scanner", () => {
   it("detects real if statements without matching strings or comments", () => {
diff --git a/test/test-file-size-budget.test.ts b/test/test-file-size-budget.test.ts
index 435cb1fdf6a..4be37554b40 100644
--- a/test/test-file-size-budget.test.ts
+++ b/test/test-file-size-budget.test.ts
@@ -8,7 +8,7 @@ import {
   evaluateTestFileSizeBudget,
   formatViolations,
   parseBudget,
-} from "../scripts/check-test-file-size-budget";
+} from "../scripts/check-test-file-size-budget.mts";
 
 describe("test file size budget", () => {
   it("counts trailing-newline and non-trailing-newline files consistently", () => {
diff --git a/test/type-safety-hotspots.test.ts b/test/type-safety-hotspots.test.ts
index 933475c1119..3235a1218b1 100644
--- a/test/type-safety-hotspots.test.ts
+++ b/test/type-safety-hotspots.test.ts
@@ -11,7 +11,7 @@ import {
   analyzeTypeSafetyHotspots,
   parseArgs,
   renderTextReport,
-} from "../scripts/type-safety-hotspots";
+} from "../scripts/type-safety-hotspots.mts";
 
 const tempDirs: string[] = [];