[u7-u7]

Problem

The badcase scaffold puts a relative filesystem path directly into an ESM import. If the checkout path contains #, Node treats the remainder as a URL fragment and cannot load fixtures.mjs. A literal %20 is decoded as a space; ? has the same problem on platforms where it is a legal path character. The generated case is unusable even though all files exist.

Change

Encode each relative path component as a URL component while preserving / separators and relative .. segments. Relative imports remain relocatable. The cross-drive Windows file-URL fallback introduced in #459 is unchanged.

Add a regression that copies the actual scaffold/helper modules into checkout directories containing # and literal %20, generates cases outside those directories, then imports and renders each generated fixture. Also cover ? on non-Windows systems.

This is independent of #503: it fixes fixture module resolution, not run IDs or event acceptance. The branch is based directly on current main and does not include #503.

Verification

• Regression on unchanged main failed with ERR_MODULE_NOT_FOUND (the helper path was truncated at #).
• node --test evals/browser/tests/*.test.mjs: 26 passed, 0 failed.
• node evals/browser/cli.mjs validate: 10 cases / 19 fixture routes validated.
• Biome 2.4.15 check of both changed files: passed, no fixes.
• git diff --check: clean.
• Tested on Linux, Node 24.22.1. Windows execution and the Rust/extension suites were not run; no Rust or extension runtime code changed.

AI assistance

Prepared and tested with OpenAI Codex. No human-review attestation is made. Submitted as a draft without requesting reviewers.