Review is intent diffing. Closeout sets up the next slice.

The design thread asks the LLM to slice the intent tree into packets — work units one level above an Issue that carry references to intent and explicit verification points. Before promotion, the design thread also runs the merged app and folds screen-level observations into the packet.

A packet with high enough DIF and resolved dependencies becomes an Issue in the implementation repo. The Issue already carries why we build this.

The implementation thread reads the packet/intent, implements, and opens a PR against the configured target branch or named lane. In the primary four-thread model an orchestrator delegates the unit through the selected session layer; herdr-only is the preferred non-preview path for collocated teams, while a timer loop remains a supported alternative.

The review thread in a different cwd diffs the PR against the packet and intent tree. Findings: pass, repair-in-place, or repair the intent. A human gives final approval before merge.

If repair-in-place: the implementation thread applies the fix to its own PR, pushes, and hands the updated PR back to the review thread. If repair-the-intent: a clarification flows back to the design thread.

PR merges into the configured target branch or named lane. The diff is written back into the intent tree as canonical, and state files (queue, runs) are updated.

On Approve the loop rewinds to step 01: from the post-merge tree, the design thread re-evaluates which packet to generate next. This rewind is what keeps the next work unit flowing reliably.