board: a card turns over to a checklist, labels and a description

Enter on a card floats a sheet over the board: its labels, a markdown
description written in the vim editor (:w writes it to the card), and a
checklist walked with j/k, ticked with Space, grown with o. Labels take
their colour from their name. A repeating card comes back with its
checklist reopened.

Code in the editor and in rendered fences is coloured from nvim's
yorha.lua, one class per highlight group, for every language
@codemirror/language-data knows; the languages load on first use.

docs/wiki/Boards-and-Agenda.md

@@ -57,7 +57,7 @@ a week fold away until `z` shows them.
 | `H` / `L` | move the card to the list on the left / right |
 | `Space` | into the done list, or back out to the inbox |
 | `o`, `c` | a new card on this list |
-| `Enter` | the card's notes |
+| `Enter` | turn the card over: labels, description, checklist |
 | `D` | due date |
 | `R` | rename the card |
 | `z` | show done cards older than a week |
@@ -65,6 +65,39 @@ a week fold away until `z` shows them.
 | `x`, `dd` | delete the card |
 | `q`, `Esc` | leave the special workspace |
 
+### The back of a card
+
+`Enter` on a card turns it over: a sheet floats over the board with its
+labels, its description and its checklist. The card stays the one under the
+board's cursor, so `D`, `R`, `H` and `L` act on it as they do on the board.
+
+| key | what it does |
+| --- | --- |
+| `j` / `k`, `gg` / `G` | down / up the checklist, its first / last step |
+| `Space`, `x` | tick the step, or untick it |
+| `o` | a new step below the cursor (`:task <text>`) |
+| `r` | reword the step (`:task! <text>`) |
+| `J` / `K` | move the step down / up |
+| `dd` | drop the step |
+| `e`, `i`, `Enter` | write the description |
+| `a` | put a label on, or take it off (`:label <name>`) |
+| `gf` | the card's notes, below |
+| `q`, `Esc` | back to the board |
+
+The description is markdown, written in the same editor as a document, vim
+and all: `:w` writes it to the card, `:q` or `Esc` in normal mode leaves, and
+`:q!` throws away what was not written. A fenced block in a language is
+coloured the way nvim colours it, written and read.
+
+Labels are lower case, and each name keeps its colour on every card and every
+board, without anything to set: the colour comes from the name. `Tab` on
+`:label` offers the ones the board already uses. The board shows a card's
+labels over its title, and `☑ 2/5` and `≡` under it when it has a checklist and
+a description.
+
+A repeating card comes back with the same labels and the same checklist, every
+step open again.
+
 ### Capturing a card
 
 `c` anywhere outside the special workspace opens `:card ` on the command line. The card goes
@@ -73,7 +106,7 @@ you stay where you were. From outside the browser, see [Capture](Capture.md).
 
 ### Notes
 
-`Enter` on a card opens its notes: a document named after the card, made in the
+`gf` on the back of a card opens its notes: a document named after the card, made in the
 root of the space the first time. Closing it goes back to the board, on the
 same card. `:card!` while reading a document makes a card that points at it.
 

docs/wiki/Commands.md

@@ -76,7 +76,7 @@ The first list is the inbox, the last list is done.
 | `J / K` | move the card down / up its list |
 | `H / L` | move the card to the list left / right |
 | `Space` | into the done list, or back out to the inbox |
-| `Enter` | the card's notes — a document, made on first use; q comes back |
+| `Enter` | turn the card over: its labels, description and checklist |
 | `o · c` | new card on this list |
 | `D` | due date: fri, tm, +3d, 10-31 … |
 | `R` | rename the card, or the list when it is empty |
@@ -131,6 +131,9 @@ do: `:w!`, `:space! <name>`, `:import!`.
 | `:due <when\|->` | due date of the card — on the board, or highlighted in the agenda: today, tm, fri, +3d, +2w, 10-31, 2026-10-31 — - clears |
 | `:repeat <rule\|->` | once the card is done, a copy comes back in the inbox: daily, weekly, monthly, yearly, +3d, +2w, +6m — - stops it |
 | `:done` | move the selected card into the done list, or back out to the inbox |
+| `:task, :step <text>` | add a step to the open card's checklist, below the cursor |
+| `:task!` | reword the step under the cursor |
+| `:label <name>` | put a label on the card, or take it off when it has it — each name keeps its colour everywhere |
 | `:list <name>` | add a column to the board |
 | `:list!` | delete the column under the cursor and every card on it |
 | `:agenda, :ag` | what is late, due this week, or in hand — across every board |
@@ -172,7 +175,7 @@ do: `:w!`, `:space! <name>`, `:import!`.
 
 | command | what it does |
 | --- | --- |
-| `:write, :w` | save the open document |
+| `:write, :w` | save the open document — or the card's description being written |
 | `:write!` | save even over a newer version saved somewhere else since this one was opened |
 | `:wq, :x` | save and leave insert/editor mode |
 | `:wq!` | save over a newer version, as :w! does, and leave the editor |