Using Claude.ai and Claude Code Together

Two Tools, Two Roles

Claude.ai and Claude Code are optimized for different parts of the development process:

Claude.ai excels at:

• Architectural thinking and technical design
• Explaining complex concepts
• Writing and editing documentation
• Reviewing code you paste into the conversation
• Planning without time pressure
• Generating options and tradeoffs

Claude Code excels at:

• Implementing decisions against your actual codebase
• Multi-step autonomous execution
• Running tests and verifying changes
• Large-scale refactors across many files
• Debugging with full context of your file system
• Scripted and automated tasks

Treating them as substitutes misses the point. They're complementary tools in a single workflow.

The Plan-Then-Implement Workflow

The most effective combined workflow:

Phase 1: Design in Claude.ai

[In Claude.ai]

I'm building a notification system for a React + Supabase app.
Users should receive in-app notifications when someone assigns
a task to them.

Current auth: Supabase Auth, user ID available as auth.uid()
Current stack: React 18, TanStack Query v5, Zustand for UI state

Design the notification system:
- Database schema for notifications table
- Real-time delivery approach (Supabase Realtime vs polling)
- React state management pattern
- Where the notification polling/subscription should live
- Component structure: notification bell, dropdown, notification item

Output a concise technical design I can hand to Claude Code.

Claude.ai produces a technical design document — schema, component structure, implementation notes.

Phase 2: Implement in Claude Code

[In Claude Code]

Implement the notification system based on this design:
[paste the technical design from Claude.ai]

Also read CLAUDE.md for project conventions.

Start with the database schema — show me the SQL before running
any migrations. Then implement the subscription hook, the Zustand
slice, and the notification bell component.

Run typecheck after each major step.

Claude Code implements the design into your actual codebase, following your conventions, running verifications, and applying changes to disk.

Diagnosing Claude Code Problems with Claude.ai

When Claude Code gets stuck or produces unexpected output, Claude.ai provides an external perspective:

[In Claude.ai]

I'm using Claude Code on a React project. It's trying to migrate
our context-based auth to Zustand but keeps introducing TypeScript
errors that compound across files.

Here's the original AuthContext.tsx:
[paste file]

Here's what Claude Code changed:
[paste modified files]

Here are the TypeScript errors:
[paste tsc output]

What's the root cause and what's the correct migration path?

Claude.ai diagnoses the problem from a clean conversational context. You then bring the precise fix back to Claude Code:

[In Claude Code]

The root cause of the TypeScript errors is [Claude.ai's diagnosis].
Make this specific change to [file]:
[precise instructions based on Claude.ai's fix]
Do not modify any other files.
Run typecheck after.

Documentation: Claude.ai Writes, Claude Code Audits

Claude.ai is far better than Claude Code at writing prose documentation. But Claude Code has access to the actual codebase to verify accuracy.

[In Claude.ai]
Write a README.md section on "Authentication Flow" based on this code:
[paste AuthContext.tsx and auth.service.ts]

[In Claude Code]
Read the Authentication Flow section in README.md.
Cross-check it against the actual auth implementation in
src/context/AuthContext.tsx and src/services/auth.service.ts.
Report any inaccuracies, outdated information, or missing steps.

This pattern produces accurate documentation — Claude.ai handles the prose quality, Claude Code handles the factual accuracy.

Code Review: Claude.ai Analyzes, Claude Code Applies

[In Claude.ai]
Review this PR diff for security issues, anti-patterns, and
code quality problems. Be specific about severity.
[paste diff]

[In Claude Code]
Apply the following code review feedback from this PR review:
[paste Claude.ai's specific feedback items]
Make only the changes corresponding to severity: HIGH items.
Run tests after each change.

Architecture Decisions: Always Claude.ai

For decisions with long-term architectural implications — database schema design, state management patterns, API design, library selection — do the thinking in Claude.ai:

• More conversational iteration
• Better at exploring tradeoffs without a bias toward "just implement it"
• Doesn't risk accidentally touching your codebase while thinking through options
• Produces documentation and decision records as natural outputs

Bring decisions to Claude Code only after they're made and you know what you want built.

Key Takeaways

• Claude.ai for design, planning, documentation, and diagnosis — Claude Code for implementation, execution, and verification
• The Plan-Then-Implement workflow is the most effective combined pattern for feature development
• Use Claude.ai as an external diagnostic partner when Claude Code is stuck
• Architecture and design decisions belong in Claude.ai; implementation belongs in Claude Code

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Try It Yourself: Take an upcoming feature or task. Write a technical design for it in Claude.ai. Then feed that design to Claude Code as implementation instructions. Note how much less back-and-forth Claude Code requires when given a clear specification vs. a vague description.