[Astro-Han]

Summary

• Swap .maka-composer-branch-picker min-height from a bare 24px to var(--h-control-sm), matching the adjacent workspace-picker.
• Add .maka-composer-branch-picker to the control-height-converge contract's CONTROL_HEIGHT list so the existing owner contract guards both pickers.

Why

The branch-picker carried a bare min-height: 24px while the adjacent workspace-picker used var(--h-control-sm) (both resolve to 24px). The bare literal is exactly the drift the control-height-converge contract exists to prevent — the branch-picker was simply missing from its CONTROL_HEIGHT list (the workspace-picker was already covered). Fix at the owner: swap the token and add the missing list entry, instead of a parallel guard. Found by the #546 Composer combined-state audit. Refs #546.

Scope

• One CSS value (branch-picker min-height) + one contract list entry. No new contract file, no helper changes, no other surfaces.

Verification

• npm run -w @maka/desktop test — 2346/2346 pass (the control-height-converge contract now covers both pickers).
• npm run -w @maka/desktop typecheck + test:checks (console/a11y/copy) — clean.
• CDP text-evidence on the live model-processing fixture (light-990 / dark-990 / light-990-reduced-motion): both pickers render min-height: 24px, content height 36px — the swap is a visual no-op. Per the repo's "style/cascade invariant: computed-style or text-contract" guidance, the control-height-converge contract is the locking layer; CDP computed-style is the substitute evidence.
• No screenshot: pixel-level appearance is unchanged (24px → token resolving to 24px); the contract + CDP computed-style are the locking layers.

Impact

None — visual no-op; no behavior, API, or migration change.

Reviewer notes

• An earlier iteration added a separate 83-line per-selector contract (composer-row-picker-size-contract) duplicating helpers from sidebar-indicator-size-contract; a Codex review flagged that as over-engineered (the owner contract already existed) and proposed merging the two picker CSS rules. The merge broke two existing contracts (control-height-converge and project-context-badge) that assert .maka-composer-workspace-picker { as a standalone rule — the repo's established convention (per refactor(ui): converge remaining sidebar row indicator sizes #743) is per-selector contracts guarding drift, not merging rules. Reassessment from first principles: the real root cause was the branch-picker missing from the owner contract's list, so the clean minimal fix is the one-line swap + one-line list entry.

Ready for review

• Verification is complete and the results above are current
• Impact, compatibility, migration, documentation, and release-note needs are addressed (none)
• User-visible UI/UX changes include visual evidence, or Verification explains why it is not applicable (visual no-op; substitute evidence above)