5chan/docs/agent-playbooks/known-surprises.md

# Known Surprises

This file tracks repository-specific confusion points that caused agent mistakes.

## Entry Criteria

Add an entry only if all are true:

- It is specific to this repository (not generic advice).
- It is likely to recur for future agents.
- It has a concrete mitigation that can be followed.

If uncertain, ask the developer before adding an entry.

## Entry Template

```md
### [Short title]

- **Date:** YYYY-MM-DD
- **Observed by:** agent name or contributor
- **Context:** where/when it happened
- **What was surprising:** concrete unexpected behavior
- **Impact:** what went wrong or could go wrong
- **Mitigation:** exact step future agents should take
- **Status:** confirmed | superseded
```

## Entries

### Portless breaks Windows installs

- **Date:** 2026-03-04
- **Observed by:** Codex
- **Context:** GitHub Actions `Test Windows` dependency install on `windows-2022`
- **What was surprising:** `portless@0.5.2` is a local dev-only tool, but keeping it in `devDependencies` makes `yarn install` fail on Windows because the package declares `win32` unsupported.
- **Impact:** Windows CI fails before build steps run, even though the app does not need `portless` there.
- **Mitigation:** Keep `portless` in `optionalDependencies` and make `yarn start` fall back to direct `vite` startup when `portless` is unavailable.
- **Status:** confirmed