Long-Running Work in Harness Engineering

Lessons in this section

1. Context Windows

   Why an agent that works over many sessions forgets what it did, redoes finished work, and how a reset with a written handoff (progress.md and git log) beats a vague compacted summary. Covers context windows, context rot and task scheduling across sessions.

2. Feature Lists

   Why an agent with a big goal and no list calls the app done at 40%, and why a list without rules gets easier on its own. Build the initializer pack: init.sh, feature_list.json with every feature failing, a progress file and four rules lines.

3. Incremental Sessions

   Why an agent that does too much in one session runs out of room mid-feature and leaves a broken build, and how one feature per session plus a clean exit (green tests, a commit, nothing half-done, a progress note) keeps every session ready for the next.

4. End-to-End Testing

   Why green unit tests and a list full of "passes": true can still hide a feature that is never turned on, and how an end-to-end check in the passes rule (Playwright for the React frontend, HTTP tests for the ASP.NET Core backend) proves each feature works in the running app.

5. Evaluator Agents

   Why an agent that grades its own work passes everything, and how a separate evaluator with a concrete rubric catches skipped tests, rewritten descriptions, unrelated edits and features that never turn on. Covers the planner, generator and evaluator roles for frontend, backend and UI design reviews.