Plan Mode

Reads the document, writes the build plan, performs none of it. You approve the plan and Agent runs it.

What it produces

One plan, committed as a numbered list of 4 to 10 steps, every step pending. Each step names the feature, its key dimensions, and the plane or face its sketch goes on, in the units the document is set to. One major feature per step, no tool names, no code.

A step reads like Sketch closed L-profile 80x50 mm legs on Front Plane, extrude 6 mm, so you can picture it before approving it.

Around the plan the answer carries a short summary, feasibility notes, any blocker, and a line telling you to switch to Agent Mode to execute it.

Before planning a change to a feature that already exists, Plan traces what is built on that feature and names the affected children in the plan.

What it reads first

Document metadata and the full feature tree on every turn. Beyond that it probes only what the plan needs: mass properties, the details of a named feature, the parent sketch when feasibility turns on it, the component and mate lists for an assembly, and a screenshot only when the layout judgment cannot be made from the tree.

All of those reads are read-only. Plan is never given a tool that changes a document.

Worked examples

Plan a mounting bracket for this motor: 4 mm plate, four M6 clearance holes on the bolt pattern, 20 mm standoff.: Reads the motor face and its hole pattern, then commits steps for the base sketch and extrude, the standoff, the hole set on the measured pattern, and the edge breaks, with the dimensions written into each step.
Plan how to add a cooling fin array to this housing without breaking the existing draft.: Traces what is built on the draft feature, names the children the fins would affect, and orders the plan so the fins land before the dress-up rather than after it.
Plan the repair for the failed loft in this part.: A repair plan, not a diagnosis. Plan stays in Plan Mode and writes the steps to fix it. If you want to know why it failed, that is Debug Mode.
Plan the assembly for this gearbox from the parts in the folder.: One step per component insert and per real joint, with the mate type named. It stops and says so if a component it needs is not resolvable rather than inventing one.

Approving the plan

The plan arrives in a card with two buttons, Build this and Deny.

Build this switches the composer to Agent Mode and sends a new turn carrying the plan and the original request that produced it. Because you already approved the plan, that Agent turn does not stop for a second approval prompt.

Deny marks the plan denied and leaves it in the transcript. Nothing runs. You can edit the request and plan again.

While the Agent turn runs, a bar above the composer shows the current step and the count, for example 3/7, and expands to the full step list.

What it cannot do

Edit anything. Plan never receives a mutating tool or the VBA tool.
Run its own plan. Only the Build this button, or switching to Agent yourself, executes it.
Diagnose. "What is wrong with this part" belongs in Debug Mode; Plan answers "what would you do about it".
Invent around a gap. If the request is infeasible, or needs a selection you have not made, it says exactly that instead of writing a plan that cannot run.

Where to go next

The plan looks right: press Build this, or read Agent Mode first for what it can and cannot change.
The plan is close but wrong in one step: rewrite the request with the correction. Writing prompts covers naming the reference precisely.
You are not sure what to build yet: Imagine Mode proposes options before you commit to one.