# Board format

The board is authored as **one 8x8 quadrant** (`board/quadrant.txt`, the top-left corner of
the board). The tooling rotates it 90° clockwise three times to build the full 16x16 board,
so every corner is identical by construction.

```
uv run dojo board validate                     # check board/quadrant.txt against the rules
uv run dojo board render -o board/board.txt    # write the full board (generated, never edit)
```

Exit codes: `0` OK (warnings allowed), `1` design errors, `2` format errors or missing file.

## Notation

Classic ASCII maze notation. Each cell is 3 characters wide with its code in the middle;
walls sit between cells.

```
+---+---+---+
| S   S | . |
+   +---+   +
| S   1   ? |
+---+---+---+
```

| Element | Walled | Open |
|---|---|---|
| Corner | `+` (always) | — |
| Between two rows | `---` | three blanks |
| Between two columns | `\|` | one blank |

- Lines starting with `#` and blank lines are ignored.
- Trailing blanks may be stripped by your editor; a missing character at the end of a line
  reads as open.
- The quadrant file is 17 lines of 33 characters.

## Cell codes

| Code | Meaning |
|---|---|
| `S` | Safe Room |
| `D` | Central Dojo |
| `.` | Tatami |
| `A` | Allenamento |
| `F` | Fatica |
| `?` | Nebbia del Dojo |
| `P` | Passo Falso |
| `K` | Sfida |
| `1`–`9` | Tunnel; the two cells with the same digit are a pair |

## Quadrant rules (format errors — the board cannot be built)

- Exactly 8x8 cells, only the codes above.
- **Top and left borders** are the outer border of the board: fully walled.
- **Right and bottom borders are seams** shared with the neighbouring quadrants. Rotation maps
  the bottom seam onto the right seam, so the right border at row *i* must equal the bottom
  border at column *i*.
- `D` cells are exactly rows 6–7, columns 6–7 (the quadrant's share of the 4x4 Dojo).
- Each tunnel digit appears on exactly two cells.

Rows and columns are 0-based, top-left is `(0, 0)`. On the full board, quadrants are numbered
clockwise: 0 top-left, 1 top-right, 2 bottom-right, 3 bottom-left.

## Tunnel links — `board/legend.toml` (optional)

The CLI reads `legend.toml` from the quadrant's folder automatically (override with
`--legend`). By default a tunnel pair links its two cells inside the same quadrant. To link across
quadrants, give the digit a `quadrant_offset`:

```toml
[tunnels.3]
quadrant_offset = 1
```

Call `a` and `b` the two cells of the digit in reading order (row by row, left to right).
With offset `o`, `a` in quadrant *k* is linked to `b` in quadrant *k + o*. Offsets are 0–3.

## Design checks (`validate` errors and warnings)

Errors:

- a wall inside the Dojo;
- a quadrant without a Dojo entrance, or an entrance opening straight into a Safe Room;
- a Safe Room that does not contain its board corner, is not connected, does not have exactly
  2 exits, or has both exits on the same side;
- a Safe Room that is a shortcut (walking through it is shorter than walking around it
  between its two exits);
- any square that cannot be walked to from a Safe Room (tunnels not counted, Dojo impassable).

Warnings:

- Safe Room size other than 3x3;
- Tatami share outside 30–40% of playable squares.

The report also lists the square mix, number of tunnel pairs and Dojo entrances, and the
shortest walk from each Safe Room into the Dojo.