diff --git a/packages/rstack/src/fmt/discovery.ts b/packages/rstack/src/fmt/discovery.ts
new file mode 100644
index 0000000..ebfed7e
--- /dev/null
+++ b/packages/rstack/src/fmt/discovery.ts
@@ -0,0 +1,60 @@
+import { getFileInfo, type FileInfoOptions } from 'prettier';
+import { resolveFmtOptions } from './config.ts';
+import { discoverFmtPaths } from './discoverPaths.ts';
+import { createFmtIgnoreMatcher } from './ignore.ts';
+import type { DiscoverFmtFilesOptions, FmtFileRequest, ResolvedFmtConfig } from './types.ts';
+
+const fileInfoOptions = {
+  ignorePath: [],
+  resolveConfig: false,
+  withNodeModules: true,
+} satisfies FileInfoOptions;
+
+const resolveFileRequest = async (
+  filePath: string,
+  config: ResolvedFmtConfig,
+): Promise<FmtFileRequest | undefined> => {
+  const options = resolveFmtOptions(filePath, config);
+
+  if (options.plugins?.length) {
+    throw new Error('Prettier plugins are not supported yet.');
+  }
+
+  const parser = options.parser ?? (await getFileInfo(filePath, fileInfoOptions)).inferredParser;
+  if (!parser) {
+    return;
+  }
+
+  return {
+    path: filePath,
+    options: {
+      ...options,
+      filepath: filePath,
+      parser,
+    },
+  };
+};
+
+/** Discovers format-ready files without reading Prettier config files or `.prettierignore`. */
+const discoverFmtFiles = async ({
+  cwd,
+  patterns,
+  config,
+}: DiscoverFmtFilesOptions): Promise<FmtFileRequest[]> => {
+  const candidates = await discoverFmtPaths({ cwd, patterns });
+  if (candidates.length === 0) {
+    return [];
+  }
+
+  const isFmtIgnored = config.ignorePatterns.length ? createFmtIgnoreMatcher(config) : undefined;
+  const filePaths = isFmtIgnored
+    ? candidates.filter((filePath) => !isFmtIgnored(filePath))
+    : candidates;
+  const files = await Promise.all(
+    filePaths.map((filePath) => resolveFileRequest(filePath, config)),
+  );
+
+  return files.filter((file): file is FmtFileRequest => file !== undefined);
+};
+
+export { discoverFmtFiles };
diff --git a/packages/rstack/src/fmt/types.ts b/packages/rstack/src/fmt/types.ts
index 8944223..16400e1 100644
--- a/packages/rstack/src/fmt/types.ts
+++ b/packages/rstack/src/fmt/types.ts
@@ -28,6 +28,22 @@ interface FormatTextOptions {
   config: ResolvedFmtConfig;
 }
 
+interface DiscoverFmtFilesOptions {
+  /** Absolute directory used to resolve input paths. */
+  cwd: string;
+  /** Files, directories, and positive or negative globs. Defaults to the current directory. */
+  patterns?: string[];
+  /** Resolved project config applied to discovered files. */
+  config: ResolvedFmtConfig;
+}
+
+interface FmtFileRequest {
+  /** Absolute path to the file. */
+  path: string;
+  /** Final Prettier options with the parser and file path resolved. */
+  options: PrettierOptions & Required<Pick<PrettierOptions, 'filepath' | 'parser'>>;
+}
+
 interface FormattedTextResult {
   status: 'formatted';
   formatted: string;
@@ -42,8 +58,10 @@ interface SkippedTextResult {
 type FormatTextResult = FormattedTextResult | SkippedTextResult;
 
 export type {
+  DiscoverFmtFilesOptions,
   FmtConfig,
   FmtConfigDefinition,
+  FmtFileRequest,
   FormatTextOptions,
   FormatTextResult,
   ResolvedFmtConfig,
diff --git a/packages/rstack/tests/fmt/discovery.test.ts b/packages/rstack/tests/fmt/discovery.test.ts
new file mode 100644
index 0000000..4b8e866
--- /dev/null
+++ b/packages/rstack/tests/fmt/discovery.test.ts
@@ -0,0 +1,82 @@
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import path from 'node:path';
+import { expect, test } from 'rstack/test';
+import { normalizeFmtConfig } from '../../src/fmt/config.ts';
+import { discoverFmtFiles } from '../../src/fmt/discovery.ts';
+import type { FmtConfig } from '../../src/fmt/types.ts';
+
+const withProject = async (callback: (rootPath: string) => Promise<void>): Promise<void> => {
+  const rootPath = mkdtempSync(path.join(tmpdir(), 'rstack fmt '));
+
+  try {
+    await callback(rootPath);
+  } finally {
+    rmSync(rootPath, { force: true, recursive: true });
+  }
+};
+
+const writeProjectFile = (rootPath: string, filePath: string, content = ''): string => {
+  const absolutePath = path.join(rootPath, filePath);
+  mkdirSync(path.dirname(absolutePath), { recursive: true });
+  writeFileSync(absolutePath, content);
+  return absolutePath;
+};
+
+const discover = async (cwd: string, patterns?: string[], config?: FmtConfig, configRoot = cwd) =>
+  discoverFmtFiles({
+    cwd,
+    patterns,
+    config: normalizeFmtConfig(config, configRoot),
+  });
+
+const relativePaths = (rootPath: string, files: Awaited<ReturnType<typeof discover>>): string[] =>
+  files.map((file) => path.relative(rootPath, file.path));
+
+test('applies config ignore patterns to discovered and explicit files', async () => {
+  await withProject(async (rootPath) => {
+    const keepPath = writeProjectFile(rootPath, 'generated/keep.ts');
+    const blockedPath = writeProjectFile(rootPath, 'generated/blocked.ts');
+    writeProjectFile(rootPath, 'src/index.ts');
+    const config = { ignorePatterns: ['generated/blocked.ts'] };
+
+    const discoveredFiles = await discover(rootPath, undefined, config);
+    const explicitFiles = await discover(rootPath, [keepPath, blockedPath], config);
+
+    expect(relativePaths(rootPath, discoveredFiles)).toEqual([
+      path.join('generated', 'keep.ts'),
+      path.join('src', 'index.ts'),
+    ]);
+    expect(relativePaths(rootPath, explicitFiles)).toEqual([path.join('generated', 'keep.ts')]);
+  });
+});
+
+test('applies config ignore patterns outside the config root', async () => {
+  await withProject(async (rootPath) => {
+    const configRoot = path.join(rootPath, 'project');
+    const filePath = writeProjectFile(rootPath, 'shared/index.ts');
+    mkdirSync(configRoot);
+
+    await expect(
+      discover(configRoot, [filePath], { ignorePatterns: ['../shared/*.ts'] }, configRoot),
+    ).resolves.toEqual([]);
+  });
+});
+
+test('resolves parsers and accepts unknown extensions with an explicit parser', async () => {
+  await withProject(async (rootPath) => {
+    writeProjectFile(rootPath, 'index.ts');
+    writeProjectFile(rootPath, 'source.custom');
+    writeProjectFile(rootPath, 'unknown.extension');
+
+    const inferredFiles = await discover(rootPath);
+    const configuredFiles = await discover(rootPath, ['source.custom'], { parser: 'babel' });
+
+    expect(relativePaths(rootPath, inferredFiles)).toEqual(['index.ts']);
+    expect(inferredFiles[0].options.parser).toBe('typescript');
+    expect(configuredFiles[0].options).toMatchObject({
+      filepath: path.join(rootPath, 'source.custom'),
+      parser: 'babel',
+    });
+  });
+});