diff --git a/scripts/generate-docs-content.ts b/scripts/generate-docs-content.ts
index 1fb3954ec..84ea93551 100644
--- a/scripts/generate-docs-content.ts
+++ b/scripts/generate-docs-content.ts
@@ -1,10 +1,10 @@
-import { execFileSync } from "node:child_process";
 import { readFileSync, writeFileSync } from "node:fs";
 import { join, relative, sep } from "node:path";
 
 import { globbySync } from "globby";
 
 import { renderHookEventsMatrix } from "./hook-events-table.js";
+import { repoRoot, runOxfmt } from "./run-oxfmt.js";
 
 /**
  * Embed the canonical `docs/**\/*.md` hierarchy into a generated TypeScript
@@ -12,21 +12,9 @@ import { renderHookEventsMatrix } from "./hook-events-table.js";
  * (npm dist bundles and bun-compiled binaries alike). The generated file is
  * committed; CI fails on drift via `pnpm run check:docs-content`.
  */
-const repoRoot = join(import.meta.dirname, "..");
 const docsRoot = join(repoRoot, "docs");
 const outputPath = join(repoRoot, "src", "generated", "docs-content.ts");
 
-// Normalize to the repo's formatter so the drift check compares stable output.
-// npx is npx.cmd on Windows; a shell resolves it. stderr is inherited so a
-// formatter failure stays diagnosable.
-const runOxfmt = (path: string): void => {
-  execFileSync("npx", ["oxfmt", relative(repoRoot, path)], {
-    cwd: repoRoot,
-    stdio: ["ignore", "ignore", "inherit"],
-    shell: process.platform === "win32",
-  });
-};
-
 // Regenerate the derived hook-event matrix inside file-formats.md before
 // embedding, so a stale committed table fails the docs-content drift check
 // (`check:docs-content` diffs this file as well as the embed). Written
@@ -34,7 +22,7 @@ const runOxfmt = (path: string): void => {
 // owns the final column layout, mirroring generate-supported-tools-tables.ts.
 const hookMatrixPath = join(docsRoot, "reference", "file-formats.md");
 writeFileSync(hookMatrixPath, renderHookEventsMatrix(readFileSync(hookMatrixPath, "utf8")), "utf8");
-runOxfmt(hookMatrixPath);
+runOxfmt([hookMatrixPath]);
 
 const filePaths = globbySync("**/*.md", {
   cwd: docsRoot,
@@ -68,6 +56,6 @@ const lines: string[] = [
 ];
 
 writeFileSync(outputPath, lines.join("\n"), "utf8");
-runOxfmt(outputPath);
+runOxfmt([outputPath]);
 // oxlint-disable-next-line no-console
 console.log(`Embedded ${entries.length} docs into ${relative(repoRoot, outputPath)}`);
diff --git a/scripts/generate-json-schema.ts b/scripts/generate-json-schema.ts
index 83e0e9e01..51f4ee206 100644
--- a/scripts/generate-json-schema.ts
+++ b/scripts/generate-json-schema.ts
@@ -1,4 +1,3 @@
-import { execFileSync } from "node:child_process";
 import { writeFileSync } from "node:fs";
 import { join } from "node:path";
 
@@ -13,6 +12,7 @@ import {
 } from "../src/constants/rulesync-paths.js";
 import { RulesyncMcpFileSchema } from "../src/features/mcp/rulesync-mcp.js";
 import { RulesyncPermissionsFileSchema } from "../src/types/permissions.js";
+import { runOxfmt } from "./run-oxfmt.js";
 
 type SchemaMeta = {
   $id: string;
@@ -70,4 +70,4 @@ generateSchema(
 );
 
 // Format generated schema files with oxfmt for consistent formatting
-execFileSync("npx", ["oxfmt", outputPath, mcpOutputPath, permissionsOutputPath]);
+runOxfmt([outputPath, mcpOutputPath, permissionsOutputPath]);
diff --git a/scripts/generate-supported-tools-tables.ts b/scripts/generate-supported-tools-tables.ts
index ada549dcf..5b2fac375 100644
--- a/scripts/generate-supported-tools-tables.ts
+++ b/scripts/generate-supported-tools-tables.ts
@@ -1,4 +1,3 @@
-import { execFileSync } from "node:child_process";
 import { readFileSync, writeFileSync } from "node:fs";
 import { join } from "node:path";
 
@@ -7,6 +6,7 @@ import { TOOL_DISPLAY, type ToolDisplayEntry } from "../src/types/tool-display.j
 import { ALL_TOOL_TARGETS, type ToolTarget } from "../src/types/tool-targets.js";
 import { formatError } from "../src/utils/error.js";
 import { replaceBetweenMarkers } from "./markdown-markers.js";
+import { runOxfmt } from "./run-oxfmt.js";
 
 const FEATURES = [
   "rules",
@@ -145,7 +145,7 @@ const main = (): void => {
   // run it here. Freshness is checked in CI by running this script then
   // `git diff` (see the `check:supported-tools` package script) — the same
   // approach as the gitignore generator, avoiding an oxfmt-vs-generator conflict.
-  execFileSync("pnpm", ["exec", "oxfmt", ...targets.map((t) => t.path)], { stdio: "inherit" });
+  runOxfmt(targets.map((t) => t.path));
 };
 
 main();
diff --git a/scripts/run-oxfmt.test.ts b/scripts/run-oxfmt.test.ts
new file mode 100644
index 000000000..ca6c411ea
--- /dev/null
+++ b/scripts/run-oxfmt.test.ts
@@ -0,0 +1,58 @@
+import { execFileSync } from "node:child_process";
+import { join } from "node:path";
+
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+import { repoRoot, runOxfmt } from "./run-oxfmt.js";
+
+vi.mock("node:child_process", () => ({
+  execFileSync: vi.fn(),
+}));
+
+const execFileSyncMock = vi.mocked(execFileSync);
+
+describe("runOxfmt", () => {
+  afterEach(() => {
+    execFileSyncMock.mockClear();
+    vi.unstubAllGlobals();
+  });
+
+  it("does not spawn oxfmt when no paths are given, so it cannot format the whole repo", () => {
+    runOxfmt([]);
+
+    expect(execFileSyncMock).not.toHaveBeenCalled();
+  });
+
+  it("passes repo-root-relative paths and runs from the repo root", () => {
+    runOxfmt([
+      join(repoRoot, "README.md"),
+      join(repoRoot, "docs", "reference", "supported-tools.md"),
+    ]);
+
+    expect(execFileSyncMock).toHaveBeenCalledTimes(1);
+    const [command, args, options] = execFileSyncMock.mock.calls[0]!;
+    expect(command).toBe("npx");
+    expect(args).toEqual([
+      "--no-install",
+      "oxfmt",
+      "README.md",
+      join("docs", "reference", "supported-tools.md"),
+    ]);
+    expect(options?.cwd).toBe(repoRoot);
+  });
+
+  it("resolves npx through a shell only on Windows", () => {
+    const platform = process.platform;
+
+    Object.defineProperty(process, "platform", { value: "win32", configurable: true });
+    try {
+      runOxfmt([join(repoRoot, "README.md")]);
+    } finally {
+      Object.defineProperty(process, "platform", { value: platform, configurable: true });
+    }
+    expect(execFileSyncMock.mock.calls[0]?.[2]?.shell).toBe(true);
+
+    runOxfmt([join(repoRoot, "README.md")]);
+    expect(execFileSyncMock.mock.calls[1]?.[2]?.shell).toBe(false);
+  });
+});
diff --git a/scripts/run-oxfmt.ts b/scripts/run-oxfmt.ts
new file mode 100644
index 000000000..b216a1fca
--- /dev/null
+++ b/scripts/run-oxfmt.ts
@@ -0,0 +1,25 @@
+import { execFileSync } from "node:child_process";
+import { join, relative } from "node:path";
+
+export const repoRoot = join(import.meta.dirname, "..");
+
+/**
+ * Format generated files with the repo's formatter so drift checks compare
+ * stable output. Shared by the generator scripts (docs content, supported-tools
+ * tables, JSON schemas) so a fix here reaches every call site.
+ *
+ * npx is npx.cmd on Windows; a shell resolves it. `--no-install` keeps npx from
+ * silently fetching a different oxfmt version when the pinned devDependency is
+ * missing, which would surface as an unexplained drift-check failure. stderr is
+ * inherited so a formatter failure stays diagnosable.
+ */
+export const runOxfmt = (paths: string[]): void => {
+  if (paths.length === 0) {
+    return;
+  }
+  execFileSync("npx", ["--no-install", "oxfmt", ...paths.map((path) => relative(repoRoot, path))], {
+    cwd: repoRoot,
+    stdio: ["ignore", "ignore", "inherit"],
+    shell: process.platform === "win32",
+  });
+};