The review loop

A Diffo review is a conversation with the agent that wrote the code.

The agent orients you first

On a change that's multi-file, structural, or just subtle, the agent opens the review with a single guide comment anchored to the whole changeset: one sentence on what the change does, plus a small mermaid diagram when the shape is easier to see than to read. It renders in the thread, so the picture is where you're already looking.

The guide has one hard rule: it orients your reading and never pre-reviews it. No verdicts, and nothing is declared "fine". That judgement is the part you came for, so the agent doesn't get to make it. When the diff explains itself, there is no guide at all, and silence is the correct outcome.

If the change moves on while you're reading, the update lands as a reply under the same guide thread rather than as a second guide.

You read

Syntax-highlighted unified/split diffs, keyboard-first navigation, context expansion, images side by side, file-level viewed tracking with a progress bar. Reading, not scrolling. (See the keyboard shortcuts.)

The review stays live

The agent keeps writing; new files appear, stats tick, fresh hunks pulse. If something you already marked viewed changes, the mark comes off and the hunk says changed since you read it.

You comment: on a line, a range of lines, a file, or the whole changeset

Every comment is a thread, marked Change (edit the code) or Question (answer it, touch nothing).

For more than one line, drag down the line numbers and release — the composer opens on the range. The line you started on is the range's anchor; the ▲/▼ on the composer's chip walk the other edge one line at a time, up past the anchor or down through it and out the other side, and every press has an exact inverse — no selection is ever lost to a stray click. Shift-click puts that edge on any line directly. Your draft is held outside the composer, so reshaping the range mid-sentence never eats what you typed.

A sent range comment stays legible in the diff: a small glyph on its first line, a thin spine down to its card, and the whole range lights up when you hover the card. The agent receives the range too — src/db.ts:214-231 (new side), not just one line.

• Send to agent delivers it now.
• Add comment queues it.
• Finish review hands the whole batch back with honest coverage stats attached ("38/42 hunks viewed, 2 files skipped").

The agent fixes and answers in place

A Change gets the edit: the agent's code changes are detected automatically, the diff updates live under your cursor, and the thread flips to addressed. A Question gets its answer as an inline reply in the thread.

The UI always shows the agent's presence (waiting / listening / working), so you know whether a Send reaches a live agent or waits in the queue. If nothing is attached, every thread carries a Copy prompt you can paste into any agent, registered or not.

No background agents, ever

Diffo spawns nothing. The agent you're already talking to stays attached through diffo poll. Your feedback returns into the session that authored the code, where all the context is.

There is no coverage gate and no verdict to sign: the comments and the coverage are what the agent receives.