jj

Verified against jj 0.45.1. Syntax lives in jj help <cmd>; this file carries the discipline, plus the danger surface no --help will confess.

You operate on a DAG

Picture the commit DAG and act on it directly. @ (the working copy) is a cursor marking where file edits land — one node among many, not the center of operations.

What makes this cheap in jj:

Every node is addressable. A change ID (the k–z letter ID in jj log) names a node forever, across rewrites. Address nodes by change ID; @ shorthand is for the node you are authoring right now.
History rebuilds itself. Rewrite any node — describe, squash, split, rebase — and descendants rebase automatically. Editing mid-DAG is routine, not surgery.
The cursor moves freely. jj new <id> / jj edit <id> park it anywhere. Work in progress is already a commit, so there is nothing to stash.
Snapshots are automatic. Every jj command folds the current file state into @. New files included — @ is the staging area, already committed.
Changes route to where they belong. Misplaced hunks move between nodes while the cursor stays put (toolbox below).

Addressing needs an ID, so every operation starts by reading the graph: