fix: isolate prepack types and secret symlink reads

CHANGELOG.md

@@ -5,6 +5,8 @@
 ### Fixes
 
 - Align POSIX and Windows handling for literal `..`-prefixed write targets, preserve whitespace in direct home-relative path inputs, and run the check suite on Windows CI. (#14; thanks @sjf)
+- Keep source prepack builds isolated from parent monorepo ambient type packages such as Bun typings. (#13; thanks @Kaspre)
+- Let secret-file reads follow symlink paths through the pinned real target unless callers opt into `rejectSymlink: true`.
 
 ## 0.2.0 - 2026-05-07
 

src/secret-file.ts

@@ -55,12 +55,26 @@ function readSecretFileOutcomeSync(
     };
   }
 
-  if (options.rejectSymlink && previewStat.isSymbolicLink()) {
-    return {
-      ok: false,
-      code: "symlink",
-      message: `${label} file at ${resolvedPath} must not be a symlink.`,
-    };
+  if (previewStat.isSymbolicLink()) {
+    if (!options.rejectSymlink) {
+      try {
+        previewStat = fs.statSync(resolvedPath);
+      } catch (error) {
+        const normalized = normalizeSecretReadError(error);
+        return {
+          ok: false,
+          code: (error as NodeJS.ErrnoException).code === "ENOENT" ? "not-found" : "invalid-path",
+          error: normalized,
+          message: `Failed to inspect ${label} file at ${resolvedPath}: ${String(normalized)}`,
+        };
+      }
+    } else {
+      return {
+        ok: false,
+        code: "symlink",
+        message: `${label} file at ${resolvedPath} must not be a symlink.`,
+      };
+    }
   }
   if (!previewStat.isFile()) {
     return {

test/coverage-more.test.ts

@@ -2,7 +2,17 @@ import fsSync from "node:fs";
 import fs from "node:fs/promises";
 import os from "node:os";
 import path from "node:path";
+import { Readable } from "node:stream";
 import { afterEach, describe, expect, it, vi } from "vitest";
+import { createBoundedReadStream, createMaxBytesTransform } from "../src/bounded-read-stream.js";
+import {
+  assertAsyncDirectoryGuard,
+  assertSyncDirectoryGuard,
+  createAsyncDirectoryGuard,
+  createNearestExistingDirectoryGuard,
+  createNearestExistingSyncDirectoryGuard,
+  createSyncDirectoryGuard,
+} from "../src/directory-guard.js";
 import { drainFileLockManagerForTest, resetFileLockManagerForTest } from "../src/file-lock.js";
 import { sameFileIdentity } from "../src/file-identity.js";
 import { readLocalFileFromRoots, resolveLocalPathFromRootsSync } from "../src/local-roots.js";
@@ -138,6 +148,46 @@ describe("small identity and lock wrappers", () => {
   });
 });
 
+describe("bounded streams and directory guard coverage", () => {
+  it("returns raw streams without limits and rejects oversized limited streams", async () => {
+    const raw = Readable.from(["ok"]);
+    const returned = createBoundedReadStream({ handle: { createReadStream: () => raw } }, undefined);
+    expect(returned).toBe(raw);
+
+    await expect(async () => {
+      for await (const _chunk of Readable.from(["ab", "cd"]).pipe(createMaxBytesTransform(3))) {
+        // Drain the stream so transform errors surface.
+      }
+    }).rejects.toMatchObject({ code: "too-large" });
+  });
+
+  it("detects changed or invalid directory guards", async () => {
+    const root = await tempRoot("fs-safe-dir-guard-more-");
+    const nested = path.join(root, "nested");
+    const filePath = path.join(root, "file.txt");
+    await fs.mkdir(nested);
+    await fs.writeFile(filePath, "not a dir", "utf8");
+
+    await expect(createAsyncDirectoryGuard(filePath)).rejects.toMatchObject({ code: "not-file" });
+    expect(() => createSyncDirectoryGuard(filePath)).toThrow("directory component");
+
+    const asyncGuard = await createAsyncDirectoryGuard(nested);
+    const syncGuard = createSyncDirectoryGuard(nested);
+    await fs.rm(nested, { recursive: true });
+    await fs.mkdir(nested);
+
+    await expect(assertAsyncDirectoryGuard(asyncGuard)).rejects.toMatchObject({
+      code: "path-mismatch",
+    });
+    expect(() => assertSyncDirectoryGuard(syncGuard)).toThrow("directory changed");
+
+    const nearest = await createNearestExistingDirectoryGuard(root, path.join(root, "missing", "x"));
+    expect(nearest.dir).toBe(root);
+    expect(createNearestExistingSyncDirectoryGuard(root, path.join(root, "missing", "x")).dir)
+      .toBe(root);
+  });
+});
+
 describe("sibling temp coverage", () => {
   it("syncs temp files and parent dirs when requested", async () => {
     const root = await tempRoot("fs-safe-sibling-more-");

test/secret-file.test.ts

@@ -68,9 +68,15 @@ describe("secret file helpers", () => {
     const root = await tempRoot("fs-safe-secret-");
     const target = path.join(root, "target.txt");
     const link = path.join(root, "link.txt");
+    const broken = path.join(root, "broken.txt");
     await fs.writeFile(target, "secret", "utf8");
     await fs.symlink(target, link);
+    await fs.symlink(path.join(root, "missing.txt"), broken);
 
+    expect(readSecretFileSync(link, "API token")).toBe("secret");
+    expect(tryReadSecretFileSync(link, "API token")).toBe("secret");
+    expectSecretReadCode(() => readSecretFileSync(broken, "API token"), "not-found");
+    expect(tryReadSecretFileSync(broken, "API token")).toBeUndefined();
     expect(() => readSecretFileSync(link, "API token", { rejectSymlink: true })).toThrow(
       `API token file at ${link} must not be a symlink.`,
     );

tsconfig.json

@@ -11,6 +11,7 @@
     "rootDir": "src",
     "strict": true,
     "target": "ES2022",
+    "types": ["node"],
     "verbatimModuleSyntax": true
   },
   "include": ["src/**/*.ts"]