Describe Animation playing and Animation length (#233)

- Animations: what the two nodes answer in each playback, what None
  asks for, and where the rule lives.
- Behaviors: both nodes in the node list.
- Development: 1615 editor checks.

Animations.md

@@ -150,6 +150,32 @@ values stay those of its first start, so a relative row does not add up. Played
 every frame, an animation never gets past its first frame — use it on a single event such as a key
 press.
 
+**Asking whether it still runs.** `Animation playing` is a data node with the inputs *object* and
+*animation* and three answers, read at the moment they are asked for — right after a `Play animation`
+in the same pulse it already says yes:
+
+- **playing** is on while the animation runs. A paused one does not run, and neither does one that
+  `Stop animation` ended or is fading out. A *Once (reset)* pass blending back to where it started still
+  runs: it still shows. In the frame `On animation finished` fires for a *Once* animation it is off.
+- **progress** is where the playhead stands on the timeline, 0 to 1, in every playback. On *Loop* it
+  starts over with each pass; on *Ping-pong* it rises to 1 at the last key and falls again on the way
+  back.
+- **time left (s)** is the time until the playhead reaches the end of its pass: the end of the
+  animation for the two *Once* modes, with *blend out (s)* added for *Once (reset)*; the end of the
+  round on *Loop*; the next turn on *Ping-pong*. A paused animation keeps its place and its time left.
+
+Leave *Animation* at None to ask for whatever runs on the object: the animation started last among
+those running, or the one started last at all when none runs. With no object, or an animation that is
+not on it, the answers are off, 0 and 0. So "no new attack while the swing runs" is one `Branch` on
+`playing` instead of a timer that has to repeat the animation's length.
+
+`Animation length` gives the seconds one pass takes, from the timeline and the frame rate alone — for
+a cooldown that is meant to be longer than the animation (`length + 0.1`).
+
+Under the hood: the rule is `playerStatus` and `leadingPlayer` in `src/core/model/animation.ts`; the
+nodes reach the animation through `GraphLookup.animation`, which hands a run only the frame count,
+the frame rate and the playback.
+
 **It runs in play only.** The Scene and Container tabs show the objects as stored; the edit mode
 has no clock. The fastest way in is right-clicking a texture → **Create animation from texture**,
 which makes a sprite of the texture and an animation over it with a `texture` row keyed frame by

Behaviors.md

@@ -228,7 +228,7 @@ playing use the same two words.
   normalized direction, so diagonals are not faster), `Compare` (two numbers count as equal up to
   float noise, a relative 1e-9, so `time - late == 6` holds without a `Round`; `Equals` does the
   same for two numbers, and for a number against a typed text that is a number, like `130`), `And/Or/Not`, `Key is down`,
-  `Mouse position`, `Mouse button`, `Is hovered`, `Is touching`, `Get velocity`, `Current state` (name and id), `Is in state` (one boolean per state) ·
+  `Mouse position`, `Mouse button`, `Is hovered`, `Is touching`, `Animation playing` (whether an animation runs on an object, its progress and time left) and `Animation length` (see [Animations](Animations)), `Get velocity`, `Current state` (name and id), `Is in state` (one boolean per state) ·
   actions `Move` (dx, dy, scale, dt — connect an event's dt for per-second movement; in the object's own axes, which a turned parent turns too; with *Collide with solids* it slides along what it hits, less friction, and outputs `blocked x/y`, `hit` and the contact `normal x/y`, see [Colliders](Colliders)), `Set position`, `Spawn`
   (asset input + x/y/z, optional parent → outputs the new object; the asset is picked on the node or arrives over an edge, from an `Asset` node, a variable or a list item. A pick saved while it was still a setting reads as that input's value, so older projects spawn as before; the same holds for the asset of `Is asset`), `Destroy` (removes the object with everything below it; with **keep children** on, only the object goes: its children move up to its parent (top level when it had none) and keep their place, rotation and size in the world, and the output `children` is the list of them, nearest level only. Its behaviors and its rigidbody go with it either way. In the editor run, children that are content of a placed container move up for the run only: their place belongs to the template, so the scene does not learn it), `Emit` (starts a particle source over, see *Particles*),
   `Play sound` / `Stop sound` (see [Sounds](Sounds): the asset says how loud and whether it loops, the node's

Development.md

@@ -18,7 +18,7 @@ php tests/php/accounts.test.php                               # the API's accoun
                                                               #   has and the web server's container has not (SKIP there)
 php tests/php/snapshots.test.php                              # the snapshot store (#231), the same way
 php tests/php/releases.test.php                               # the release store (#266), the same way
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1613 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1615 editor checks, screenshots in /tmp/gm-e2e-*.png
 GM_STEPS=20 node tools/e2e.mjs                                # or 1-12, or 6,20 — a subset while working on one step
 ./e2e.sh start [GM_STEPS]                                     # the same run detached, see below
 ./e2e.sh status                                               # live progress, or the last run's result