Determine when to use plan mode vs direct execution

Use plan mode for everything, since planning before acting is good practice.

A one-line fix with a clear stack trace gains nothing from a planning round and pays latency and tokens for it every time.

Plan mode earns its cost when there are several valid approaches or the change is wide.

Go straight to execution on a migration because the target is already decided.

Deciding the destination is not the same as knowing what it touches; the rework surfaces after the edits are spread across dozens of files.

Breadth is the trigger for planning, independent of how settled the goal feels.

Run the discovery phase in the main conversation so the findings are on hand.

Discovery is the most verbose phase, so it exhausts the window before implementation begins and the summary competes with raw output.

Isolate discovery in the Explore subagent and bring back the summary.

Treat plan mode and direct execution as a single choice for the whole task.

It forces planning overhead onto mechanical steps, or skips planning for the one decision that needed it.

Plan the investigation, then execute the agreed approach directly.