Fold new context into a plan that already exists — re-synthesize PLAN.md, show the user the delta, and leave finished work finished. Plan only: write no source files.

Locate

Find the issue workspace per references/issue-workspace.md, then read its PLAN.md and CONTEXT.md. You are revising them, not starting over. No workspace for this issue means it was never planned; send the user to /plan-implementation.

Gather

Append the new context, from the argument or the conversation, to CONTEXT.md. Create it if the first plan skipped it.

When the new context leaves a real decision open — not just a detail — grill it out with /grilling before re-synthesizing.

Re-synthesize

Rebuild PLAN.md from the issue plus the grown CONTEXT.md, using the issue workspace template and recording rules. Two things hold fixed:

Completed tasks stay done. A [x] task keeps its check unless the new context explicitly undoes it.
Status stays where it was (Planned / In Progress), unless the new context moves it.

update-plan

Locate

Gather

Re-synthesize