Board DSL — Splits

# Board DSL — Splits

A column can split into named sections. This page covers a column's `split:`
block and its per-section modifiers. See the [reference index](./index.md) for
the board header and the other constructs.

## Split block (a column's `split:`)

A column can split into sections. Each section keeps a **required `name`**
(every addressable board unit stays addressable — split-sections are a future
ref target).

```dwsd-board
columns:
  - name: Review
    split:
      direction: horizontal      # omit for the vertical default
      of:
        - { name: doing, status-category: waiting }
        - { name: done,  status-category: done }
```

| Field (on the split block) | Values / shape | Default | Diagnostic on misuse |
|----------------------------|----------------|---------|----------------------|
| `direction` | `horizontal` \| `vertical` | `vertical` (omitted) | `board.invalid-split` (unknown value → defaults to vertical) |
| `of` | list of section entries (each a bare string OR an object) | `[]` | per-section `board.invalid-split` |

| Field (on each `of` section) | Values / shape | Default | Diagnostic on misuse |
|------------------------------|----------------|---------|----------------------|
| `name` | string (**required** — D-09) | — | `board.invalid-split` (section skipped when missing) |
| `status-category` | single value, closed set `to-do` \| `in-progress` \| `done` \| `waiting` \| `assess` (→ section `tag`) | (none) | `board.invalid-status-category` (value dropped, no tint) |
| `wip` | number → max only; OR `[min, max]` | (none) | `board.invalid-wip` |
| `aging` | string | (none) | (none) |
| `agreements` | string OR string list — per-section working agreements | (none) | tolerant |
| `interactions` | string OR string list — per-section meeting / interaction pointers | (none) | tolerant |

Note the per-section tint key is **`status-category:`** — a single closed-set
value that maps to the section's `tag` field (the parser takes element `[0]` of
the validated category). The pre-D-12 singular `status:` key is **removed**; use
`status-category:`. A split block with zero valid sections is dropped.

**Per-section `agreements:` / `interactions:` render on the section surface.**
Each `of` section may carry its own `agreements:` / `interactions:`, and they
render as the grouped agreements / interactions bucket **on that section's
surface** (the same chip → shared drawer mechanism described in
[Anchors, agreements & interactions](./anchors.md#anchors-agreements--interactions)) — not
only via external markers. (The named-split production `split <name>` was
**retracted** in Plan 13-10; a split block carries no label, only its sections
carry a `name`.)

![Column split with per-section modifiers](../../images/split.png)

![Per-section split agreements on the section surface](../../images/split-agreements.png)