Sprint Contract — Multi-Agent Quality System#

Based on Anthropic's harness design for long-running apps: separate the agent doing the work from the agent judging it.

Core Principle#

Never let the builder evaluate their own work on complex tasks. LLMs reliably praise their own output — even when it's mediocre. An independent evaluator, tuned to be skeptical, catches what self-evaluation misses.

Architecture#

text

Planner (you/human) → Generator (sub-agent) → Evaluator (independent sub-agent)
     ↑                                              |
     └──────────── feedback loop ←──────────────────┘

Workflow#

1. Write a BRIEF.md with Sprint Contract#

Every task gets a BRIEF.md. The Sprint Contract section is mandatory — it lists specific, testable completion criteria.

markdown

# Task Brief

## Background
[Why this task exists]

## Objective
[What to build/fix]

## Sprint Contract (Completion Criteria)
- [ ] Criterion 1 (specific, verifiable)
- [ ] Criterion 2
- [ ] ...

⚠️ Write criteria specific to THIS task. No generic checklists.

## Related Files
[File paths relevant to the task]

## Constraints
[Tech stack, prior decisions, known pitfalls]

## Handoff Requirements
Write a HANDOFF.md when done, containing:
- What was done (file change list)
- Design decisions made (and why)
- What's left / known issues
- Everything needed for reporting to the human

2. Spawn Generator (Builder)#

The generator receives the BRIEF.md and builds against the Sprint Contract. Key rules for the generator prompt:

• Work against the Sprint Contract criteria
• Self-check each criterion before handing off
• Write HANDOFF.md when done
• Write files first, read references second (output > research)

3. Spawn Evaluator (Independent QA)#

After the generator finishes, spawn a separate agent as evaluator. The evaluator prompt must include:

The Sprint Contract — copied from BRIEF.md, to verify each criterion.

4 Evaluation Dimensions (select what's relevant):

DimensionWhat to checkFunctional completenessEvery Sprint Contract criterion passesUser experienceFlow is intuitive, no dead endsVisual qualityLayout, spacing, colors are professionalCode/content qualityNo errors, clean logic, no regressions

The critical prompt line:

"Your job is to find problems, not to praise. If everything looks fine, you probably didn't test carefully enough. Report issues honestly — better a false alarm than a missed bug."

4. Decision Gate#

Based on evaluator feedback:

• All criteria pass → Ship it
• Criteria fail → Feed evaluator report back to generator for fixes
• Architecture issues → Escalate to human

When to Use Each Mode#

Task complexityGeneratorEvaluatorExampleSimple (< 30 min)Sub-agentSelf-evaluate, mark "⚠️ untested"Fix a typo, update configMedium (30 min - 2 hr)Sub-agentIndependent sub-agentNew feature, bug fixComplex (2+ hr)Claude Code / ACPIndependent sub-agent + human reviewArchitecture change, new project

Sprint Contract Examples#

See references/contract-examples.md for project-specific contract templates.

Key Insights from Anthropic's Research#

1. File-based communication — Agents talk through files (BRIEF.md, HANDOFF.md), not conversation
2. Evaluator calibration — Default LLMs are too lenient; explicitly prompt for skepticism
3. Sprint scoping — One feature at a time; don't bundle unrelated work
4. Opus 4.6 + 1M context — Context anxiety is gone; sprint decomposition is less critical, but evaluator still adds value at task boundaries
5. Evaluation criteria shape output — The wording of your criteria directly steers what the generator produces