Cline Plan mode vs Act mode: the workflow that gets the most out of both

Published 2026-04-10 by Owner

Cline 3.0 introduced an explicit Plan/Act split. In Plan mode, Cline reasons about a task and produces a plan in chat without making changes. In Act mode, Cline executes the plan with full tool use (reading files, running commands, editing). You toggle between modes in the UI.

The split is more than a UI feature. Used correctly, it changes how reliable the autonomous loop is.

What each mode is for

Plan mode:

• Discuss the task with the model before any changes
• Iterate on the approach without burning tokens on tool use
• Produce a plan that the user agrees to before execution
• Switch models freely (Plan can be a strong model, Act can be cheaper)

Act mode:

• Execute the plan with file reads, edits, and command runs
• Self-correct on tool errors
• Commit to the chosen approach

The mental model: Plan mode is a whiteboard conversation. Act mode is the IDE.

Why this matters more than expected

The failure mode of single-mode autonomous agents (Aider, early Cursor agent, raw Cline before 3.0) is “the agent commits to an approach early and then keeps doing more of the same wrong thing.” The first turn picks a structure; subsequent turns build on it. If the first turn was wrong, the structure is wrong throughout.

Plan/Act fixes this by inserting a thinking step that’s not committed to anything. You can argue with the plan. You can ask for alternatives. You can change scope. None of this costs tool calls or file edits.

When the plan is solid, Act executes it efficiently. When the plan is weak, you don’t waste an Act session finding out.

The workflow that works

After a few months on Cline 3.x:

1. Start in Plan mode
2. Describe the task at moderate detail
3. Read the plan; verify it covers the cases
4. If wrong, refine the prompt and ask again (still in Plan mode)
5. When the plan is solid, switch to Act mode
6. Cline executes
7. Review the changes; commit if good, revert and replan if bad

The pattern that doesn’t work: jumping straight to Act for non-trivial tasks. The autonomous loop will produce something, but the something is biased toward whatever pattern Cline first matched. Plan first, act second, even if it feels redundant.

The token cost

Plan mode is meaningfully cheaper than Act mode for most tasks. No tool use means no file reads, no command output in context, no diff blocks. A typical Plan turn is 2-5k tokens; a typical Act turn is 8-20k tokens.

For a 30-minute Cline session:

• Plan-then-Act: ~$1.20 average
• Act-only: ~$2.40 average

Half the cost on average, with better outcomes because the plan is reviewed before tools run.

When Plan mode isn’t worth it

For trivial tasks (“rename this variable across the file”), Plan mode is overhead. The plan is “I’ll rename it”; you wouldn’t have asked unless you wanted that. Skip Plan mode for these.

The threshold I use: if the task requires reading more than one file or making changes in more than one file, Plan first. If it’s a one-file, one-purpose change, go straight to Act.

Per-mode model selection

Cline 3.4+ supports per-mode models. Configuration:

Plan mode → Claude 3.5 Sonnet (or your strongest model)
Act mode → DeepSeek Coder V3 or Claude 3.5 Haiku (cheaper, fast)

The architect/editor split applies. The strong model thinks; the cheap model executes the explicit plan.

This works because once the plan exists, executing it is mechanical. The cheap model can produce the right tool calls when told what to do. It struggles when it has to figure out what to do.

The cost difference is meaningful. For a Plan-heavy session (lots of thinking, less doing), use the strong model on Plan. For an Act-heavy session (long executions of well-understood plans), the cheap Act model dominates the bill.

A mistake I see often

People in the Cline Discord ask why their sessions are unreliable. The most common cause: they’re using Act mode for everything because “Plan mode is for beginners.” It’s not. Plan mode is for not-wasting-money-on-bad-ideas.

The corollary: if the model gives you a plan you don’t like in Plan mode, that’s the cheapest possible signal that the model is wrong. Cancel and refine the prompt. The version of you that switched straight to Act would have spent 10x more to discover the same thing.

Plan mode as a tool for thinking

A side benefit: Plan mode is a useful tool even when you’d ultimately do the work yourself. Asking Cline to plan a refactor surfaces:

• Files I’d missed
• Edge cases I hadn’t considered
• Alternative approaches I hadn’t thought of

Sometimes I read the plan, decide I disagree with the approach, and write the refactor myself based on a clearer understanding of what’s involved. The model didn’t do the work but it accelerated my thinking.

This is a useful re-frame: Plan mode can be a thinking aid even outside the agent loop. It’s cheap, fast, and you don’t have to follow the plan.

What’s still rough

A few things I’d improve about Plan/Act:

Mode switching forgets context. When I switch from Plan to Act, the act sometimes doesn’t fully internalize what was discussed in Plan. The plan is in the conversation, but Act can drift slightly. I usually paste the agreed plan as the first Act turn to anchor it.

No partial Plan execution. I sometimes want Cline to act on the first half of a plan and stop, so I can verify before continuing. There’s no built-in pause-after-step. Workaround: split the plan into two prompts.

Plan mode is too permissive on assumptions. The model in Plan mode sometimes plans based on assumptions about my codebase that turn out to be wrong. The plan looks fine; it’s only in Act that the assumption breaks. A “verify these assumptions first” mode would help.

These will probably improve. As of Cline 3.4, Plan/Act is the most important workflow lever the tool offers, and using it well is a meaningful productivity edge over treating Cline as a single-mode agent.