refactor: repro tsx CJS node_modules resolution bug on Node 24+

Replace statuses/JSON repro with superagent-based HTTP fetch so the
test exercises tsx's CJS require() hook — the actual failure surface
on Node 24 where tsx wrongly rewrites intra-node_modules relative
paths (.js → .jsx/.ts etc.).

- swap statuses → superagent (CJS pkg with internal require() calls)
- src/status.ts: fetchJson() wraps superagent GET
- src/status.test.ts: offline local http server, two JSON round-trips
- add tsx-pr (file:../tsx-fix) — local build of PR #803 fix branch
- add test:pr script; drop @types/statuses
- update README to document new bug, fix, and all four test variants

Refs privatenumber/tsx#800, privatenumber/tsx#803

Author: torbjornvatn

README.md

@@ -1,43 +1,78 @@
-# tsx JSON bug reproduction
+# tsx CJS node_modules resolution bug reproduction
 
-Minimal repo that proves a regression introduced in **tsx v4.21.1** where `.json` files
-are incorrectly transformed as JavaScript, producing the error:
+Minimal repo that proves a regression where tsx on **Node 24+** incorrectly applies
+TypeScript extension resolution (`.js → .ts/.tsx/.jsx`) to `require()` calls made
+*inside* `node_modules`, breaking CJS packages such as **superagent**.
 
 ```
-SyntaxError: …/statuses/codes.json: Unexpected token 'v', "var _00="C"... is not valid JSON
+Error: Cannot find module '.../mime-db/index.jsx'
+    at Object.<anonymous> (.../superagent/lib/node/index.js:...)
 ```
 
+Tracked in: [privatenumber/tsx#800](https://github.com/privatenumber/tsx/issues/800)  
+Fixed by: [privatenumber/tsx#803](https://github.com/privatenumber/tsx/pull/803) (linked locally as `tsx-pr`)
+
 ## What's in here
 
-| File                 | Purpose                                                  |
-| -------------------- | -------------------------------------------------------- |
-| `src/status.ts`      | Imports `statuses` (which loads `codes.json` internally) |
-| `src/status.test.ts` | Three `node:test` assertions that exercise `status.ts`   |
+| File                   | Purpose                                                              |
+| ---------------------- | -------------------------------------------------------------------- |
+| `src/status.ts`        | Uses **superagent** (a CJS package) to `GET` a URL and return JSON  |
+| `src/status.test.ts`   | Two `node:test` assertions — spins up a local HTTP server, no network needed |
+| `../tsx-fix/`          | Local checkout of the PR branch (`imevanc/tsx-fix@fix/node-modules-extension-rewrite`), built and linked as `tsx-pr` |
 
 ## Reproduce
 
 ```bash
 npm install
 
-# ✅ Passes with tsx@4.21.0
+# ✅ Passes — tsx@4.21.0 (unaffected, before the regression window)
 npm run test:good
 
-# ❌ Fails with tsx@4.21.1
+# ❌ Fails — tsx@4.21.1 (regression introduced here)
 npm run test:bad
+
+# ❌ Fails — tsx@latest (still unfixed in the published release)
+npm run test:latest
+
+# ✅ Passes — tsx PR #803 (local build of the fix branch)
+npm run test:pr
 ```
 
-Both scripts run the **identical** test command, only the tsx version differs:
+All scripts run the **same** test command, only the tsx version differs:
 
 ```
-node --test-reporter spec --import=tsx[-good|-bad]/esm --test 'src/**/*.test.ts'
+node --test-reporter spec --import=tsx[-good|-bad|-latest|-pr]/esm --test 'src/**/*.test.ts'
 ```
 
-The error only occurs with Node version 24, if I run `nvm use 22` before `npm run test:bad`, the tests pass just fine.
+> **Note:** The failure only manifests on **Node 24+**.  Running `nvm use 22` before
+> `npm run test:bad` makes the tests pass because on Node 22 CJS `require()` calls
+> never go through the ESM hooks.
+
+## Why it breaks
+
+On Node 24, `module.registerHooks()` intercepts CJS `require()` calls through ESM
+sync hooks.  When a CJS file inside `node_modules` does `require('./relative/path')`,
+tsx's resolver applies `mapTsExtensions()`, probing `.ts/.tsx/.jsx` candidates.
+`nextResolve` for each probe re-enters the hooks recursively and fails for every
+extension — including the original `.js` — because Node's native CJS resolver can't
+resolve these paths in the recursive hook context.
+
+## The fix (PR #803)
 
-## Why it breaks (this section is AI generate, so it might not be the actual reason)
+In `createResolveSync`, early-return to Node's native resolver when:
 
-`statuses` ships a plain JSON file (`node_modules/statuses/codes.json`).  
-Starting in 4.21.1, tsx's ESM loader began applying its esbuild transform pipeline
-to `.json` files. esbuild compiles JSON into a JS module (`var _00 = …`), but Node's
-`--experimental-json-modules` / import assertions path then tries to re-parse the
-_compiled output_ as raw JSON — and fails.
+1. The hook context is a CJS `require()` call,
+2. the parent file is inside `node_modules`, and
+3. the specifier is a relative file path.
+
+This prevents tsx from ever trying to rewrite extensions for intra-`node_modules`
+requires, which matches the behaviour on Node 22.
+
+## Building `tsx-pr` locally
+
+```bash
+cd ../tsx-fix          # the cloned PR branch
+pnpm install
+pnpm build
+# then back in this repo: npm install (picks up file:../tsx-fix)
+```