The PRD-First Workflow: A Cost-Effective Multi-Model Development Pattern

When user K asked in Discord about burning through money using Claude Opus for app development, reddev shared a workflow pattern that several community members found valuable:

"Plan with opus, create a markdown PRD, use another model to code, then get Claude to review"

This simple advice encapsulates a powerful cost-saving strategy that lets you use premium models where they matter most.

The Four-Phase Workflow

Phase 1: Plan with Opus (or Your Best Model)

Use your most capable model for the initial planning phase. This is where you need:

• Clear thinking about architecture
• Edge case identification
• Technical decision-making

The planning phase typically uses far fewer tokens than implementation, so spending on a premium model here is worthwhile.

Phase 2: Create a Markdown PRD

The Product Requirements Document becomes your handoff artifact. This is the key insight - by having Opus (or Sonnet 4.6) produce a detailed PRD in markdown, you create a portable specification that cheaper models can execute against.

A good PRD includes:

• Feature specifications
• Technical requirements and constraints
• API contracts
• File structure
• Success criteria

Phase 3: Code with a Cheaper Model

Now hand the PRD to a more cost-effective model for implementation. Community members mentioned several options:

reddev noted:

"Claude is great with UX / front end (Gemini too), codex great at the nuts & bolts/backend, Kimi is 80% as good as others but 90% cheaper."

riprsa suggested:

"Try codex, its almost free on chatgpt 20$ sub. You can set codex as main model and use opus when you have a more specific context."

The PRD gives the cheaper model clear guardrails, reducing hallucination and keeping implementation on track.

Phase 4: Review with Claude

Bring Claude back for code review. Premium models excel at:

• Catching subtle bugs
• Identifying security issues
• Suggesting architectural improvements
• Verifying the implementation matches the PRD

Implementing This in OpenClaw

You can implement this workflow in several ways:

1. Session-level model switching:

/model anthropic/claude-opus-4-6

Use this for planning, then switch models for coding.

2. Sub-agent delegation: Have your main agent (on Opus) spawn a coding sub-agent on a cheaper model, passing the PRD as context.

3. Config-based model routing: Set up different agent profiles for different tasks, each configured with the appropriate model.

Model Strengths Reference

Based on community experience:

Why This Works

1. Concentrated intelligence where it matters: Complex decisions happen in planning and review - phases that use relatively few tokens.

2. Clear handoffs reduce errors: The PRD creates an explicit contract between phases, reducing the chance of context drift.

3. Cheaper models perform well with constraints: Given clear instructions (the PRD), budget models can execute implementation tasks effectively.

4. Review catches implementation issues: Having a premium model verify the work catches problems before they compound.

Community Discussion

This tip came from the #general channel (February 2026). The full thread included discussion about model pricing, ChatGPT subscription usage for Codex, and model-specific strengths.

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