What happened?

fallow audit --base main appears to analyze against a temporary checkout of the base branch that does not have node_modules installed. In a React Native app whose tsconfig.json extends ./node_modules/@react-native/typescript-config/tsconfig.json, this causes a broken tsconfig chain warning and resolver fallback during audit.

In my case that fallback matters because the repo uses tsconfig path aliases heavily (@/*).

Observed warnings:

WARN node_modules directory not found. Run `npm install` / `pnpm install` first for accurate results.
WARN Broken tsconfig chain: Tsconfig not found /var/folders/.../fallow-audit-base-.../link-v2/node_modules/@react-native/typescript-config/tsconfig.json. Falling back to resolver-less resolution for affected files. Relative and bare imports still work, but tsconfig path aliases (e.g., `@/...`) will not. Fix the extends/references chain to restore alias support.

This happens even when the working tree itself has dependencies installed. The problem seems to be specifically the base-side temp checkout used by audit --base.

Why this is surprising

Issue #242 and its maintainer response on May 1, 2026 point users toward fallow audit --base "$BASE" --quiet as the preferred integrated path for hooks / gating. That makes this edge case important for React Native / Expo repos that extend tsconfig from node_modules.

Reproduction

A reduced shape that reproduces the problem:

1. Create a JS/TS repo with:

   • tsconfig.json containing:

     {
       "$schema": "https://json.schemastore.org/tsconfig",
       "extends": "./node_modules/@react-native/typescript-config/tsconfig.json",
       "compilerOptions": {
         "baseUrl": ".",
         "paths": {
           "@/*": ["src/*"]
         }
       }
     }

   • source files that import through @/...
   • @react-native/typescript-config installed locally

2. Ensure main contains that config.

3. On a feature branch, run:

npx fallow audit --base main --format json

4. Observe warnings about:
   • node_modules directory not found
   • broken tsconfig chain in a temp path like .../fallow-audit-base-.../node_modules/@react-native/typescript-config/tsconfig.json
   • fallback to resolver-less resolution, which explicitly says tsconfig path aliases will not work

What I tested locally

• Running focused commands like fallow dead-code --changed-since main, fallow health --changed-since main, and fallow dupes --changed-since main did not surface the same temp-base warning in the same way.
• Running fallow audit --base main consistently reproduced the warning.
• Installing dependencies in the current working tree did not remove the warning.
• Replacing tsconfig.json to extend a committed local base file instead of ./node_modules/... appears to avoid the structural problem, but that is a repo-level workaround rather than a clear answer about supported audit behavior.

Expected behavior

One of these, depending on intended design:

1. fallow audit --base <ref> should preserve enough dependency/config context on the base-side analysis so that tsconfig chains extending into node_modules still resolve correctly, or
2. the docs should explicitly call out that audit --base may fall back to resolver-less mode for repos whose tsconfig extends points into node_modules, with guidance on the recommended workaround.

Questions

1. Is this expected behavior for audit --base today?
2. Is there a supported way to make base-side temp analysis resolve node_modules-backed tsconfig chains correctly?
3. For React Native / Expo repos, is the recommended path to vendor/commit the base tsconfig instead of extending from ./node_modules/... if we want reliable audit results?

Fallow version

Reproduced with 2.65.0 and 2.66.0.

Operating system

macOS

Configuration

The important part is a repo with:

• tsconfig.json extending ./node_modules/@react-native/typescript-config/tsconfig.json
• tsconfig path aliases like @/*
• fallow audit --base main