Claude Code Ultraplan & Plan Mode: Complete Guide (2026)

One of the most common mistakes developers make with AI coding tools is jumping straight into implementation, which is exactly what Claude Code Ultraplan is designed to prevent. They describe a feature, Claude starts editing files, and three minutes later something that looked straightforward has branched into six unexpected changes across a dozen files. The result is a mess that is harder to understand than the original problem.

Claude Code solves this with two dedicated planning features: Plan Mode and Ultraplan. Both put Claude into a read-only state where it can explore your codebase, ask clarifying questions, and draft a structured plan before writing a single line of code. The difference is scale - Plan Mode runs locally in your terminal for focused tasks, while Ultraplan hands the planning work to a cloud-based Opus 4.6 session for complex, multi-file projects that benefit from deeper analysis.

This guide covers both features end to end: how to activate them, how to read and annotate the plans they produce, and how to decide which one to reach for on any given task. By the end, planning before coding will feel like the obvious default rather than an extra step.

What Is Claude Code Plan Mode?

Plan Mode is a read-only operating mode built directly into the Claude Code CLI. When Plan Mode is active, Claude can read files, search your codebase, run read-only commands, and ask questions - but it cannot write files, edit code, execute shell commands, or make any changes to your project. The constraint is total. Claude gathers information and thinks out loud, then produces a structured plan.md file that breaks your task into discrete steps with dependencies and execution order. If you have not yet wired Claude Code into your workflow, the Claude Code tips and tricks guide walks through the keyboard shortcuts and configuration that make planning sessions feel natural.

The core value is separation of concerns. Implementation and planning are fundamentally different cognitive activities, and mixing them creates problems. When Claude starts editing immediately, it commits to an approach before fully understanding the scope. Edge cases surface mid-implementation. Files that should have been touched at the start get missed until the end. Plan Mode forces a complete survey of the problem space first.

The plan Claude produces is not a rough outline - it is a specific, ordered task breakdown that reflects the actual structure of your codebase. It identifies which files need to change, what order those changes should happen in, and where dependencies exist between steps. You can review the plan, annotate it, ask Claude to revise sections, and only then authorize execution. That review window is where most of the value is captured, and the Claude Code simplifier pre-commit hook guide shows how to enforce a similar review gate on the implementation side.

When to Use Plan Mode

Plan Mode pays for itself on tasks that touch multiple parts of your codebase simultaneously. A focused bug fix in a single function rarely needs it. But any of these scenarios are strong signals to plan first:

Changes touching three or more files. When a single task requires coordinated edits across multiple files - say, adding a new API endpoint that requires updating a route file, a controller, a schema, a service layer, and an OpenAPI spec - planning first reveals the full scope before you are committed. Without a plan, it is easy to complete four of the five files and not notice the fifth until something breaks. This pattern shows up constantly in GitHub pull requests where a feature flag is added to one file but never wired through the rest of the stack.

Refactors that move code between files. Reorganizing module structure, extracting a shared utility, or splitting a large file into smaller pieces all require careful dependency tracking. Plan Mode lets Claude map every import and reference before touching anything, which prevents the partial-refactor state where some files reference the new location and others still reference the old one. The Claude Code hooks deep dive shows how to chain a planning session into a pre-commit verification step.

New features that touch existing modules. Adding a feature is rarely additive-only. It often means extending existing interfaces, adding cases to existing switch statements, updating tests, and sometimes modifying database schemas. A plan surfaces all of these touchpoints upfront, and pairs well with the structured prompts described in the Claude Code prompt engineering guide.

Tasks where you are not sure of the scope. If you are about to type a prompt and you find yourself thinking “this might also affect…”, that uncertainty is a signal to plan first. Plan Mode converts uncertainty into a concrete list.

How to Activate Plan Mode in Claude Code

There are two ways to enter Plan Mode, and both are equally valid depending on your workflow preference.

Method 1: Shift+Tab (keyboard shortcut)

Press Shift+Tab twice while in an active Claude Code session. The first press cycles Claude into auto-accept mode. The second press cycles it into Plan Mode. You will see the indicator at the bottom of your terminal change to show that plan mode is on. To return to normal mode, press Shift+Tab a third time, which cycles back to the default interactive mode.

The cycling order is:

1. Normal interactive mode (default)
2. Auto-accept mode (Claude executes without asking for confirmation)
3. Plan Mode (read-only, no writes or executions)

If you press Shift+Tab once and Claude starts auto-accepting tool calls, press it again to move into Plan Mode.

Method 2: /plan command (v2.1.0+)

Type /plan directly in the Claude Code prompt. This is the more explicit method and is useful if you want to enter Plan Mode without cycling through auto-accept first. Type /plan before describing your task and Claude will begin in planning mode immediately. For teams who want planning baked into a custom slash command, the Claude Code skills tutorial covers how to package the workflow as a reusable skill.

> /plan
⏸ plan mode on

> Refactor the authentication module to support OAuth2 alongside the existing API key auth

Once Plan Mode is active, you can describe your task as you normally would. Claude will begin reading files, exploring your directory structure, and asking clarifying questions. It will not make any changes until you approve the plan and exit Plan Mode.

Confirming Plan Mode is Active

Look for the visual indicator at the bottom of your terminal. It will show a pause icon alongside text indicating that plan mode is on. If you do not see this indicator, press Shift+Tab again or type /plan again to confirm the state.

Reading and Editing the Plan

Once Claude has finished exploring your codebase and drafting the plan, it creates a plan.md file at the root of your project. This file is the artifact that bridges planning and execution.

A well-structured plan.md will contain:

• Task summary - A one-paragraph description of what the overall change accomplishes
• Files to modify - A list of every file that needs to change, with a brief reason for each
• Files to create - Any new files that need to be added
• Execution steps - An ordered list of discrete implementation steps, numbered and specific
• Dependencies - Notes on which steps must complete before others can begin
• Edge cases and risks - Anything Claude noticed during exploration that might complicate implementation

The execution steps section is the most important part. Each step should be specific enough that Claude can implement it without re-reading the plan. Vague steps like “update the authentication flow” are a sign the plan needs more detail. Specific steps like “Add OAuthProvider enum to src/types/auth.ts and export it” are what you want.

Opening the Plan in Your Editor

Press Ctrl+G to open the plan.md file directly in your configured editor. This lets you annotate, rearrange, or remove steps before execution begins. You can add comments for Claude to follow, delete steps that are out of scope, or flag sections that need revision.

Requesting Revisions

While still in Plan Mode, you can ask Claude to revise the plan. Describe what is missing or incorrect and Claude will update the plan.md file. Common revision requests include:

• “Step 3 is missing - we also need to update the OpenAPI spec at docs/api.yaml”
• “Steps 4 and 5 are in the wrong order - the schema migration has to happen before the service layer changes”
• “Remove the part about updating the tests - those are covered in a separate ticket”

Once the plan reflects the actual work to be done, exit Plan Mode by pressing Shift+Tab to return to normal mode, then ask Claude to execute the plan.

What Is Claude Code Ultraplan?

Claude Code Ultraplan is the cloud-based counterpart to local Plan Mode. While Plan Mode runs entirely on your machine using whatever model is active in your CLI session, Ultraplan routes the planning task to a dedicated Claude Code web session running Anthropic’s Opus 4.6 model inside the Cloud Container Runtime (CCR).

The session runs for up to 30 minutes in the cloud. During that time, Opus 4.6 explores your repository, reads your codebase, and drafts a plan using the same read-only constraints as local Plan Mode - no writes, no edits, no executions. The key difference is capability: Opus 4.6 is Anthropic’s most powerful reasoning model, and running it against your full codebase in a dedicated cloud container means the resulting plan is substantially more thorough than what a local session can produce.

You activate Ultraplan with the /ultraplan command in your Claude Code CLI, and then you are free to keep working in your terminal while the cloud session runs in the background. When the plan is ready, you open it in a browser, review the sections, leave comments, request revisions, and choose where to execute it - either in the web interface or back in your local terminal.

Ultraplan requires a Claude Code web account at code.claude.com and a GitHub repository that Claude can access. Because the CCR environment connects to your repo directly, Ultraplan does not require your local environment to stay open while the plan is being drafted. The Cloud Container Runtime is the same execution layer described in the Opus 4 announcement.

How to Use Claude Code Ultraplan

Follow these steps to run your first Ultraplan session.

Step 1: Ensure prerequisites are met

Before running /ultraplan, confirm that:

• Your project is in a GitHub repository that your Claude Code web account can access
• You have a Claude Code account at code.claude.com
• You are logged in to Claude Code in your terminal (claude --login if not)

Step 2: Type /ultraplan in your terminal

Start a Claude Code session and type the command:

> /ultraplan

Handing off to Ultraplan...
A planning session is now running at code.claude.com
Session ID: ultraplan-8f3a2c1d
Open in browser: https://code.claude.com/sessions/ultraplan-8f3a2c1d

Claude will display a session ID and a link to follow in your browser.

Step 3: Describe your task

After typing /ultraplan, describe the task in as much detail as you can. The more context you provide, the more targeted the plan will be:

> /ultraplan

Refactor the payments module to support multiple payment providers
(Stripe, PayPal, Braintree) using a strategy pattern. Currently
everything is hardcoded for Stripe. The module is in src/payments/
and is used by checkout.ts, subscription.ts, and admin/billing.ts.

The description is sent to the cloud session along with repository access. Opus 4.6 begins reading your codebase immediately.

Step 4: Keep working while the plan runs

The cloud session runs independently. You do not need to wait at your terminal. Continue with other tasks, work on a different branch, or take a break. The session will run for up to 30 minutes. Many teams use this window to triage GitHub issues or review open pull requests while the plan compiles.

Step 5: Open the plan in your browser

Follow the link from Step 2 to open the plan in the Claude Code web interface. You will see the plan organized into sections - similar to plan.md but displayed in a structured web UI.

Step 6: Review, comment, and request revisions

In the browser, you can:

• Read each section of the plan
• Leave inline comments on specific steps
• Request revisions to sections that need adjustment
• Ask Ultraplan to explore specific files more deeply

This is the review window. Take your time here. A thorough plan review catches scope issues, incorrect assumptions, and missing steps before any code is written.

Step 7: Choose your execution environment

Once the plan is approved, you can execute it in the web interface (which runs in the same CCR environment) or export it back to your local terminal session. The export option downloads the plan.md file and opens it in your active Claude Code session, ready for local execution.

Ultraplan vs Plan Mode: When to Use Each

Both features serve the same goal - plan before you code - but they suit different situations. Use this framework to decide which one to reach for.

The simplest decision rule is: Plan Mode for focused tasks, Ultraplan for projects you would normally break into multiple tickets.

If you would describe a task to a colleague as “a quick change,” use Plan Mode. If you would describe it as “a significant piece of work,” use Ultraplan.

A useful secondary signal is whether the task has dependencies you are not fully sure about. Ultraplan’s deeper exploration with Opus 4.6 is specifically valuable when the full impact of a change is not immediately obvious. If you find yourself saying “I think this might also affect…” - that uncertainty is a strong signal for Ultraplan.

Pro Tips for Better Plans

Getting good plans out of both features comes down to how you frame the task. These tips apply equally to Plan Mode and Ultraplan.

State the goal explicitly, not just the method. “Refactor the auth module to use strategy pattern” gives Claude less to work with than “Refactor the auth module to support OAuth2 and SAML alongside existing API key auth, using a strategy pattern to keep the new providers interchangeable.” The goal context helps Claude identify which files and interfaces are actually involved.

Mention files you already know are relevant. If you know the task involves src/services/auth.ts and src/middleware/session.ts, say so. Claude will still explore the full codebase, but these explicit references anchor the exploration and reduce the chance of missing adjacent dependencies.

Use /compact before planning in long sessions. If you have been working in a Claude Code session for a while, the context window may contain conversation history that is not relevant to the planning task. Type /compact to summarize and compress that history before entering Plan Mode. This gives Claude more context budget to spend on actual codebase exploration.

Ask Claude to identify risks in the plan. After Plan Mode produces a plan.md, ask: “What are the three highest-risk parts of this plan?” This surfaces the steps where implementation is most likely to go wrong and gives you a chance to add detail or restructure before execution begins.

Review execution order carefully. The most common plan defect is steps in the wrong order. Look for any step that reads or depends on an artifact that an earlier step should have created. If you see that, reverse the order or add an explicit dependency note.

Keep your CLAUDE.md updated. Both Plan Mode and Ultraplan read your project’s CLAUDE.md file at the start of the planning session. If your conventions, tech stack, or architectural patterns are well-documented there, the plans will reflect them. A stale or sparse CLAUDE.md leads to plans that do not match how your team actually works. The official Claude Code memory documentation covers the precedence rules between project, user, and enterprise CLAUDE.md files.

Frequently Asked Questions

What is ultraplan in Claude Code?

Ultraplan is a cloud-based planning feature in Claude Code that routes your planning task to a dedicated Claude Code web session running Opus 4.6 in Anthropic’s Cloud Container Runtime. You activate it with the /ultraplan command in your CLI. The session runs for up to 30 minutes, explores your GitHub repository in read-only mode, and produces a structured plan you review in a browser before any code is written. It is distinct from local Plan Mode, which runs in your terminal using your current model.

How do you activate plan mode in Claude Code?

Press Shift+Tab twice from within an active Claude Code session to cycle into Plan Mode (the first press enters auto-accept mode, the second enters Plan Mode). Alternatively, type /plan in the prompt if you are running Claude Code v2.1.0 or later. Both methods put Claude into a read-only state where it can explore your codebase but cannot write files or execute commands. A visual indicator at the bottom of the terminal confirms Plan Mode is active.

What is the difference between plan mode and ultraplan in Claude Code?

Plan Mode runs locally in your terminal using your active model. It is immediate, requires no account beyond your standard Claude Code subscription, and works with any project regardless of whether it is in a GitHub repository. Ultraplan routes the planning task to a cloud session running Opus 4.6, runs for up to 30 minutes, requires a Claude Code web account and a GitHub repository, and produces a more thorough plan for complex, multi-file projects. Plan Mode is best for focused tasks; Ultraplan is best for large-scope work.

Does ultraplan require a paid Claude Code subscription?

Ultraplan requires a Claude Code web account at code.claude.com. You should check the current plan requirements on the official Ultraplan documentation page as pricing and tier access can change. At a minimum, Ultraplan uses Opus 4.6 in a dedicated cloud container, which is a resource-intensive operation, so it is associated with paid tiers rather than free access. Local Plan Mode, by contrast, uses whatever model your current CLI session is running and is available to all Claude Code users.

How do I use Shift+Tab in Claude Code to enter plan mode?

While you have an active Claude Code session open in your terminal, press Shift+Tab. This cycles the mode indicator at the bottom of the terminal. The first press switches to auto-accept mode. The second press switches to Plan Mode, showing the planning mode indicator. If you want to go directly to Plan Mode without cycling through auto-accept, use the /plan command instead - type /plan in the prompt and press Enter.

When should I use ultraplan instead of regular plan mode?

Use Ultraplan when the task is large enough that you would normally break it into multiple tickets, when it touches ten or more files across multiple modules, when you are unsure of the full scope and want the deepest possible exploration, or when you need architectural-level planning for a new feature that affects core parts of your system. Use local Plan Mode for focused tasks that touch three to ten files, quick refactors, or any situation where you need a plan immediately rather than waiting up to 30 minutes for a cloud session.

Can I use ultraplan without a GitHub repository?

No. Ultraplan requires a GitHub repository because the Cloud Container Runtime connects directly to your repo to explore the codebase. If your project is not in a GitHub repository, or if your Claude Code web account does not have access to the repo, Ultraplan will not be able to run. In that case, local Plan Mode is the alternative - it reads your local filesystem directly and has no repository requirement. You can run Plan Mode on any project, regardless of version control setup.

The Bottom Line

Plan Mode and Ultraplan transform Claude Code from a fast code editor into a thoughtful collaborator. Reach for Plan Mode in the terminal whenever a task touches three or more files; reach for Ultraplan when the work is large enough that you would split it into multiple tickets. The 30 seconds you spend choosing the right mode pays back in hours of avoided rework.

Related Guides

• Claude Code Tips and Tricks: Save Hours With These Power User Workflows
• Claude Code Hooks Deep Dive: Automate Your AI Coding Workflow
• Building Custom Skills for Claude Code: Complete Tutorial
• Claude Code Prompt Engineering: Get Better Results
• Claude Code Simplifier Pre-Commit Hook

External Resources

• Claude Code Official Documentation - Anthropic’s complete reference for the CLI, modes, and commands
• Ultraplan Documentation - Cloud planning session reference and pricing
• Claude Opus 4 Announcement - Background on the Opus model that powers Ultraplan
• Claude Code GitHub Repository - Issue tracker and community examples