Claude Code Ultraplan vs Ultrathink: Cloud Planning and Deep Reasoning

Cloud planning, terminal kickoff, browser sign-off — that was the loop Anthropic shipped when Claude Code v2.1.92 introduced /ultraplan alongside Claude Code Web in April 2026. A r/ClaudeAI thread by shanraisshan (~613 upvotes) became the community reference.

Update — September 1, 2026: Anthropic removed the Ultraplan research preview. The /ultraplan command, ultraplan keyword, and browser refine-from-plan option are gone. This post keeps the historical workflow, community feedback, and what to use instead — plus ultrathink, a separate feature people often confuse with Ultraplan.

TL;DR — Ultraplan vs ultrathink

/plan vs /ultraplan vs /ultrathink vs /ultrareview

Rule of thumb: /plan for approval gates, ultrathink for hard thinking inside an approved direction, /ultrareview before merge. Ultraplan's cloud-planning slot is now /plan + Claude Code on the web.

What /ultraplan did (historical — removed September 2026)

Anthropic's cloud-first pattern for coding agents — also visible in /ultrareview and /autofix-pr — treats the terminal as the power-user entry point and Claude Code Web as the review and execution surface. See also /ultraplan in the explainx.ai dictionary.

For planning specifically:

1. Kick off in the CLI — /ultraplan refactor the auth module to use JWT refresh tokens (or any task description).
2. Draft in the cloud — Claude builds a structured implementation plan in a remote session, not in your local context window alone.
3. Review in the browser — Open the plan at claude.ai/code (or the linked session). Add inline comments on specific steps, files, or assumptions — closer to a doc review than a chat transcript.
4. Choose execution path — Approve and run remotely on Anthropic's stack, or hand the plan back to your local Claude Code session for execution where you already have hooks, MCP servers, and file watchers wired up.

The design goal was legibility before execution: a plan you could read, annotate, and share without scrolling a terminal buffer. Anthropic later removed the preview — see official removal notice.

What ultrathink is (prompt keyword, not a command)

There is no /ultrathink in the official Commands index. ultrathink is keyword detection in the Claude Code harness: include it anywhere in a normal message and the CLI adds an instruction to reason more deeply for that turn only. See also /ultrathink in the explainx.ai dictionary.

ultrathink about why this migration deadlocks under concurrent writes,
then propose a fix that keeps backward compatibility

Only ultrathink is special. Phrases like "think hard", "think more", and "think deeply" pass through as ordinary prompt text — they do not trigger extended reasoning. Older guides described a "think" hierarchy (think → think hard → ultrathink); that hierarchy is not how Claude Code works today.

ultrathink vs /effort and thinking toggles

Practical default: leave the session at high effort for most work. Reach for ultrathink on individual gnarly prompts instead of running max effort for an entire afternoon of routine edits. See model vs effort in Claude Code when the keyword is not enough.

When to use ultrathink (and when to skip)

Use it when:

• You need deeper analysis on one question — race conditions, subtle auth bugs, migration ordering.
• You want extra reasoning without bumping session effort for every subsequent turn.
• You are inside an approved /plan direction and need hard thinking on a specific step.

Skip it when:

• You need a planning approval gate — use /plan, not ultrathink.
• You need session-wide depth — use /effort max instead of repeating ultrathink every message.
• You need pre-merge review — use /ultrareview or /code-review ultra.

Do not confuse ultrathink with ultraplan token burn: ultraplan was cloud session overhead; ultrathink is per-turn thinking tokens. Different cost profiles, same "ultra" marketing residue.

The ultraplan workflow (historical — April 2026)

# From any Claude Code session (v2.1.92+)
/ultraplan Add rate limiting to the public API using Redis

# Claude opens or links a cloud ultraplan session
# → review in browser, comment inline on steps
# → Execute remotely  OR  Send to CLI

Pair with Claude Code Web setup (/web-setup, /login) if you have been on API-key-only auth — cloud features expect a Claude.ai account link similar to /ultrareview.

/ultraplan vs /plan vs Codex-style planning (historical context)

Local Plan Mode remains the default for "show me what you will touch before you touch it" on everyday edits. With ultraplan removed, teams that wanted browser-reviewed plans use Claude Code on the web or local /plan plus stakeholder review out of band.

For OpenAI's parallel, see Ethan Mollick on Codex as bookmark agent and Codex usage limits — the industry pattern is the same (cloud agent, local entry), even when the planning UI differs.

What people are asking (April–September 2026)

"The browser review is weirdly satisfying"

Several r/ClaudeAI commenters noted that commenting on plan sections in a web doc felt more natural than approving a wall of terminal text. That matches how loop engineering teams already treat plans as artifacts — checkable, diffable, storable — not throwaway chat.

Non-git repos break the flow

A recurring failure mode: /ultraplan assumes git-backed project context like other cloud Claude Code paths. Monorepos without git, scratch folders, and zip-download workflows reported errors or empty plans. Fix: git init and commit baseline state, or use local /plan until your repo matches what Claude Code Web expects.

Plans siloed in cloud vs local session

Another friction point: the ultraplan session lives in the cloud, separate from your active terminal context. Inline comments do not automatically hydrate local CLAUDE.md memory or MCP state. After "Send to CLI," you still need to re-anchor — paste constraints, point at the approved plan, or resume with explicit file paths. Cloud-first does not mean context-free.

Plan quality on Opus disappointed some users

Even with git, thread participants reported shallow or generic plans on Opus for complex refactors — the kind of work where local /plan with a rich CLAUDE.md sometimes outperformed cloud draft. Mitigations that showed up in discussion:

• Front-load constraints in the /ultraplan prompt (files off-limits, test commands, migration rules).
• Run a local /plan first, then /ultraplan only when you need browser review — treat cloud as presentation layer, not replacement for repo context.
• Stack agent skills that encode planning templates.

Outages, quotas, and "ultraburn"

April 2026 coincided with Claude Code Web outage frustration in the same communities celebrating /ultraplan. Cloud planning sessions consume usage on Anthropic's side; meme terms like ultraburn, onlyplans (plans without execution), and ultralogin (auth friction before you plan) spread as shorthand for paying twice — once to plan in cloud, again to execute. Budget with the same discipline as enterprise token governance: cap scope, avoid ultraplan on tasks /plan handles in two minutes.

Where /ultraplan fits in a cloud vs local stack

Anthropic is not alone in pushing terminal trigger → cloud worker. Grok Bot's 200+ cloud agent org runs the same shape at a different scale — specialized bots, shared external memory, cloud agents doing the long work while humans orchestrate from chat or CLI.

For Claude Code specifically, think in layers:

The agent harness still owns permissions, stop conditions, and tool access — cloud routing and ultrathink are options inside it, not replacements for harness design.

What to use instead of /ultraplan

Anthropic's removal notice points to two replacements:

# Plan locally, execute remotely (documented pattern)
claude --permission-mode plan
# save plan → commit → push
claude --cloud "Execute docs/auth-migration-plan.md"

Common mistakes (September 2026)

1. Treating ultrathink as /ultrathink — It will not appear in the / menu. Type the word in your message.
2. Expecting /ultraplan to still work — Update runbooks to /plan and Claude Code on the web.
3. Using ultrathink for planning scope — Deep reasoning on a bad plan still produces a bad plan. Use /plan for approval gates; use ultrathink for hard analysis within an approved direction.
4. Confusing ultrathink with ultraplan token burn — Ultraplan was cloud session overhead; ultrathink is per-turn thinking tokens.

The "ultra" family in Claude Code

Same prefix, four different mechanisms.

When to use cloud planning (post-Ultraplan)

Use cloud planning when:

• You want remote execution after sign-off and your laptop should stay free.
• The task is large enough that a durable plan artifact beats a quick chat approval.

Skip it when:

• The change is one file — local /plan is faster and cheaper.
• The repo is not in git or cloud sync is blocked by compliance (ZDR orgs, Bedrock-only deployments — same class of restrictions as /ultrareview).
• You need tight MCP + hook integration from minute zero — start local; use cloud only for execution after sign-off.

Use ultrathink when:

• A single turn needs deeper analysis (race conditions, subtle auth bugs) without changing session effort for everything else.

Skip ultrathink when:

• The problem is bad scope or missing context — fix CLAUDE.md, use /plan, then optionally add ultrathink inside an approved direction.

Command reference snapshot

Full index: Claude Code slash commands reference.

Version note: /ultraplan required Claude Code v2.1.92+ when it existed. Run claude update and check /release-notes for current commands.

Related on explainx.ai

• Claude Code commands — complete reference · full slash-command index
• Model vs effort in Claude Code · when ultrathink is not enough
• Claude Code Plan Mode guide · local planning replacement for Ultraplan
• /ultrareview cloud bug hunt · the pre-merge sibling in the "ultra" family
• Loop engineering for coding agents · plans as loop artifacts with stop conditions
• What is an agent harness? · where cloud routing fits in the stack
• Grok Bot — 200+ cloud agents, one engineer · cloud orchestration at scale
• AI token costs and governance · budgeting ultraburn
• Ethan Mollick on Codex agents · OpenAI's parallel cloud-local split

Official docs: Ultraplan (removed) · Commands — Claude Code · Claude Code on the web

Ultraplan was removed per Anthropic's September 2026 documentation. ultrathink keyword behavior, effort defaults, and cloud pricing reflect releases as of September 1, 2026. Re-check code.claude.com/docs before updating team runbooks.