Claude Code vs Claude.ai: Which to Use for Which Job

The Short Version: Different Access, Different Jobs

Both run on the same Claude models. The difference is what they can touch. Claude.ai is a conversation with your uploads, Projects, connectors, and a sandbox for code execution and files. Claude Code is an agent that works inside your repository: per its docs, it reads your codebase, edits files, runs commands, and works with git, from the terminal, IDE extensions, the desktop app, or the web.

That makes the choice less about which is smarter and more about whether the task needs ground truth from your code. If it does, chat is working from whatever you pasted, which is usually incomplete or out of date.

This post is about choosing between two Anthropic surfaces. For comparing Claude Code with other coding agents, see Cursor vs Claude Code vs Codex.

What Each Can Touch

Which To Use for Which Job

Plan in Chat, Execute in the Repo

The pattern that works best for many developers is to separate deciding from doing. Chat is a cheap place to argue with yourself: compare three approaches, poke holes in a schema, or decide what to cut. Once the decision is made, the repo agent should get a crisp brief, not the whole debate.

Claude Code also has its own planning: in plan mode it explores and reads without editing source files. Use that for plans that depend on how the code is actually structured. Use chat for plans that depend on product, users, or tradeoffs the code cannot tell you.

The handoff is where most of the value is lost or kept. A template:

Goal: Add CSV export to the Reports page.

Decided (do not revisit):
- Server-side generation; files over 10k rows stream.
- Columns match the on-screen table, in the same order.
- No new dependencies.

Out of scope: PDF export, scheduled exports.

Acceptance criteria:
1. "Export CSV" button on /reports, disabled while loading.
2. Exported file opens in Excel and Google Sheets without
   encoding issues (UTF-8 with BOM).
3. Tests cover empty report and a 25k-row report.
4. Typecheck, lint, and tests pass.

Start by reading the Reports page and its data loader, then
propose a short plan before editing.

Worked Example: Where the Handoff Saved a Day

Illustrative scenario: a solo developer spends 40 minutes in Claude.ai designing an export feature. The chat settles on streaming for large files, then later reverses a decision about column order. If they paste the full 30-message chat into Claude Code, the agent sees both versions of the column decision and has to guess which one won.

Instead, they write the ten-line handoff above. Claude Code reads the Reports page, notices the table already has a column-config array, proposes reusing it, and the developer approves. The handoff carried decisions, not history, so the agent spent its effort on the code.

The reverse handoff matters too. When Claude Code finishes, ask it for a summary of what changed and any follow-ups, and bring that back to chat if you are writing docs or a changelog.

Setting Up Each Side So Handoffs Are Cheap

Handoffs are expensive when each side starts from zero. A little setup on both ends removes most of the repetition.

• In Claude.ai: keep a Project per product with a short product brief, the current architecture summary, and your conventions. Planning chats inside that Project start with the right background without you pasting it.
• In Claude Code: keep a CLAUDE.md in the repo with build, test, and lint commands, architecture notes, and rules the agent must follow. The docs describe it as a file Claude Code reads at the start of every session.
• Keep them in sync: when an architectural decision changes, update both. A stale Project brief produces chat plans that contradict the repo, which is exactly the failure this split is meant to avoid.
• Store handoffs in the repo: a short docs/decisions note per feature gives future sessions, human or agent, the reasoning without the chat.

When not to split at all: small, well-understood changes. If you already know the fix, go straight to Claude Code and describe it in two sentences. The plan-then-execute pattern earns its overhead on work with real design choices, not on a typo fix.

Failure Modes of Using the Wrong Tool

• Designing against stale code in chat. You paste a file from last week, get a clean plan, and it conflicts with changes you forgot. If the answer depends on the code, let the agent read the code.
• Open-ended strategy in the repo agent. Asking Claude Code "what should our onboarding be?" invites it to explore files for answers that are not in the code. It burns time and usage.
• Copy-paste coding from chat. Pasting generated code into many files by hand skips the tests and type checks the agent would have run.
• No acceptance criteria. Without them, an agent's "done" means "I stopped." See vibe coding to production for review habits.

Usage matters too: on a Claude subscription, both draw on your plan's usage, so a long chat debate plus a long agent session can exhaust a session window faster than either alone. See planning work around the 5-hour window.

Where ClaudeKit Fits

ClaudeKit runs on claude.ai, so it helps with the chat half of this workflow. Pin the messages where decisions were made, so writing the handoff is a matter of reading your pins rather than rereading the thread. The Handoff Brief can turn a long planning conversation into a compact summary to start from; edit it into acceptance criteria before giving it to Claude Code.

Export the planning chat as Markdown if you want the reasoning saved in your repo's docs folder, and hover the usage circle before starting a long planning session that you will follow with an agent run.