hrt-change-size-gate

A change that bundles several independent user stories inflates every downstream phase (specs, design, tasks, apply) at once, and quality drops. This gate catches it at proposal, before any artifact is written.

The gate biases toward one change. Over-decomposition is the more common failure — a single broad story spanning many layers or capabilities is normal, not a split signal. The agent MUST NOT split on its own: it proposes, the user decides.

When to run

Inside the proposal phase, after "What Changes" and "Capabilities" are drafted as working content, before either is finalized.

The check

The agent MUST test the draft "What Changes" list for two or more items that satisfy ALL three conditions:

1. Independently shippable — shipping only that item (not the others) still gives a user something to use and verify.
2. No dependency — the item has no code or data dependency on another item in the list.
3. Distinct capability — no two of the items fall under the same capability in the Capabilities section being drafted. (specs/** does not exist yet this phase — check the Capabilities list, not disk.)

Example — independent: "add CSV export" + "add a dark-mode toggle" (ship either alone). Not independent: "add CSV export" + "add a permission check for export" (the check is meaningless without export — one slice).