What is Plan Mode and how do you activate it?

Plan Mode is a Claude Code mode that prioritises reasoning and planning before execution. It's activated with /plan or the corresponding keyboard shortcut. In Plan Mode, Claude doesn't write code or execute actions — it only thinks and plans with you.

How do I ask adversarial questions to Claude effectively?

The most useful questions are the ones that invite Claude to be critical of you: «What potential problems do you see in this approach?», «What assumptions am I making that might be wrong?», «If this failed, why would it fail?». You can also explicitly ask it to act as a devil's advocate.

Why is Level 2 critical for teams working with client data?

Because the consequences of designing architecture poorly or skipping security considerations are much more severe when third-party data is involved. In Plan Mode you can ask: «What privacy and security considerations am I missing?» before writing a line of code.

Does Level 2 slow down development?

In the short term, the planning session adds time. In the medium term, it significantly reduces time lost on rewrites, architectural bugs, and technical decisions that need to be undone. Most teams observe a net increase in speed within the first 2 weeks.

Level 2 — The Planner

13 March 2026

Mindset: «Claude is a partner»

The jump from Level 1 to Level 2 is conceptual, not technical. It's not about learning a new feature — it's about changing the nature of the conversation. You stop giving orders and start deliberating.

At Level 2, before writing a single line of code, you open Plan Mode and discuss architecture, risks, and alternatives. Claude can see what you can't — and at this level you actively ask it to.

You're here when...

You use Plan Mode before building anything
You regularly ask: «What am I missing here?»
You discuss architecture before writing a single line of code
You let Claude push back on your ideas — and you value it
You use extended thinking for complex decisions

Skills to master

Plan Mode + extended thinking before every build
Collaborative questioning: «What would an expert think here that I'm not seeing?»
Asking: «What are the unintended consequences?»
Letting Claude be adversarial — spawn a devil's advocate sub-agent to challenge your plan
Nudging Claude toward better paths when it defaults to the wrong one

Trap: Planning blind

Great conversation — but Claude is still guessing about your project, your stack, your preferences. You don't know what you don't know — especially dangerous when dealing with other people's data. Words alone aren't enough.

You can have a brilliant planning session and still get a mediocre result if Claude doesn't have access to the real files, design screenshots, existing code, or examples that define your standard. Dialogue without context is still a dialogue in the dark.

How to unlock Level 3

The unlock is understanding that the conversation doesn't matter if Claude doesn't have the right information. The next step is starting to feed it real context: files, screenshots, examples, existing code.

At Level 3 you learn to manage what Claude sees at each moment — and equally importantly, what it does NOT see. Context curation is the master skill of Level 3.

Next steps

If you want your team to develop this collaborative AI planning mindset, we can work on it in practical sessions.

Frequently asked questions

What is Plan Mode and how do you activate it?: Plan Mode is a Claude Code mode that prioritises reasoning and planning before execution. It's activated with /plan or the corresponding keyboard shortcut. In Plan Mode, Claude doesn't write code or execute actions — it only thinks and plans with you.
How do I ask adversarial questions to Claude effectively?: The most useful questions are the ones that invite Claude to be critical of you: «What potential problems do you see in this approach?», «What assumptions am I making that might be wrong?», «If this failed, why would it fail?». You can also explicitly ask it to act as a devil's advocate.
Why is Level 2 critical for teams working with client data?: Because the consequences of designing architecture poorly or skipping security considerations are much more severe when third-party data is involved. In Plan Mode you can ask: «What privacy and security considerations am I missing?» before writing a line of code.
Does Level 2 slow down development?: In the short term, the planning session adds time. In the medium term, it significantly reduces time lost on rewrites, architectural bugs, and technical decisions that need to be undone. Most teams observe a net increase in speed within the first 2 weeks.