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Reading and approving a diff

A diff is read line by line before being approved, and approval itself is now done through a menu of named options rather than a free keystroke.

A diff marks with a minus what disappears from a file and with a plus what gets added. A surgical modification, one that touches only what is necessary, is recognisable by how short these two blocks are, few lines removed, few lines added, concentrated on the exact point of the request.

A menu, not a free keystroke

When Claude proposes to modify a file, the permission prompt that appears is now a menu of named options, Yes, Yes and don't ask again, which holds until the end of the session for a file edit, and No. This edit is not saved to the file itself: the permissions table shows it, it lasts until the end of the session. It is only for a shell command or a WebFetch domain that a remembered choice survives the session and a restart, permanently and per repository. You move to the option you want and confirm with Enter. The Tab key opens, before confirming, a comment field attached to the chosen option, which lets you explain a refusal rather than leaving it silent. None of the named options in this menu let you directly edit the content of the diff shown at that exact spot. Editing proposed content goes through a different channel, the Ctrl+G combination, which opens a plan in your default text editor before approval, a mechanism distinct from editing a code diff already proposed at this stage.

Reading before approving, line by line

Reading line by line remains the gesture that protects, whatever the approval mechanism in place. A diff that touches twenty files for a change announced as localised deserves a refusal, or an explicit comment added through Tab, rather than a quick approval. Here is an example of a minimal diff, produced on files created for the demonstration:

mkdir -p /tmp/demo-diff
printf 'ligne un\nligne deux\nligne trois\n' > /tmp/demo-diff/avant.txt
printf 'ligne un\nligne deux modifiée\nligne trois\n' > /tmp/demo-diff/apres.txt
diff /tmp/demo-diff/avant.txt /tmp/demo-diff/apres.txt

The output shows exactly one line removed and one line added, exactly the expected scope of a surgical modification. A diff that, for the same request, also moved lines one and three would fall outside the necessary scope.

The mode that removes this prompt entirely, --dangerously-skip-permissions, is equivalent to the bypass permission mode presented in the lesson on permissions and plan mode. This mode is refused by default if the session is running as root or under sudo on Linux and macOS, unless inside a recognised sandbox, and its first interactive use displays a warning dialog that must be accepted once.