/**
 * The behavior graph editor: binding to the selection, dragging nodes, the palette (row click
 * and Enter), connecting ports, deleting, the live highlight while playing, variables.
 */
export async function graph(t) {
  const {
    check,
    sleep,
    saved,
    evaluate,
    json,
    find,
    shot,
    click,
    clickText,
    drag,
    mouse,
    locate,
    mutate,
    typeText,
    press,
    holdKey,
    undo,
    state,
    select,
    stop,
    asset,
    api,
    navigate,
    projectId,
    showTab,
  } = t;
  const nodeOf = async (id) => (await asset('mover')).graph.nodes.find((n) => n.id === id);
  const graphCounts = async () => {
    const g = (await asset('mover')).graph;
    return { nodes: g.nodes.length, edges: g.edges.length };
  };
  const variableKeys = async () => (await asset('mover')).variables.map((v) => v.key).join(',');

  // 6a. Selecting the Mover asset binds the graph; the Behavior tab shows it.
  await clickText('Mover');
  await showTab('graph');
  check(
    'graph editor shows the selected behavior',
    (await evaluate(`__gm.graph.current()`)) === 'mover' && (await evaluate('__gm.tab()')) === 'graph',
  );
  await shot('16-graph');

  // 6b. Drag a node: clicking its title selects it, dragging moves it (undoable).
  const axisBefore = await nodeOf('n-axis');
  const axisPos = await json(`__gm.graph.nodeAt('n-axis')`);
  // The fit zoom follows the canvas size, so 60 screen pixels are 60/zoom graph units, not 60.
  const fitZoom = Number(await evaluate('__gm.graph.zoom()'));
  await drag(axisPos.x, axisPos.y, axisPos.x + 60, axisPos.y + 40);
  let s = await state();
  const axisAfter = await nodeOf('n-axis');
  check(
    'dragging a node selects and moves it',
    s.selection?.kind === 'node' &&
      s.selection.nodeId === 'n-axis' &&
      Math.abs(axisAfter.x - (axisBefore.x + 60 / fitZoom)) <= 2 &&
      Math.abs(axisAfter.y - (axisBefore.y + 40 / fitZoom)) <= 2,
    `${JSON.stringify(s.selection)} ${axisBefore.x},${axisBefore.y} → ${axisAfter.x},${axisAfter.y}`,
  );
  check(
    'node inspector shows the node',
    Boolean(await evaluate(`__gm.locate('Axis input')`)) &&
      Boolean(await evaluate(`__gm.locate('DATA NODE')`)),
  );
  await undo();
  const axisUndone = await nodeOf('n-axis');
  check(
    'undo moves the node back',
    axisUndone.x === axisBefore.x && axisUndone.y === axisBefore.y,
    `${axisUndone.x},${axisUndone.y}`,
  );

  // 6c. Typing a query and then *clicking* a row adds exactly one node: the search field's
  //      blur-commit must not pick the first match as well.
  // Bare canvas, searched rather than guessed: the console panel below shortens the canvas.
  const bare = await json('__gm.graph.emptySpot()');
  const beforeClickPick = await graphCounts();
  await click(bare.x, bare.y, 'right');
  check('node palette opens (row-click case)', Boolean(await evaluate(`__gm.locate('Search nodes…')`)));
  await typeText('stop');
  const stopRow = await locate('Stop game'); // nothing else on screen shows this label
  await click(stopRow.x, stopRow.y);
  const afterClickPick = await graphCounts();
  check(
    'clicking a palette row adds exactly one node',
    afterClickPick.nodes === beforeClickPick.nodes + 1,
    JSON.stringify({ beforeClickPick, afterClickPick }),
  );
  check('palette closed after row click', !(await evaluate(`__gm.locate('Search nodes…')`)));
  await undo(); // so the next step finds the same empty spot and the expected graph
  check('undo removes the clicked node again', (await graphCounts()).nodes === beforeClickPick.nodes);

  // 6d. Right-click the empty canvas → palette → search "log" → Enter adds a Log node.
  const before13 = await graphCounts();
  await click(bare.x, bare.y, 'right');
  check('node palette opens', Boolean(await evaluate(`__gm.locate('Search nodes…')`)));
  // Unfiltered the palette holds far more nodes than fit, so it grows to the full height it may
  // have – and that height is the canvas minus a tenth at each end. Shifting it up to fit used to
  // put the entire gap above it and leave it flush on the bottom edge. Opened this far down it ends
  // up with a tenth at both ends; the gap above is what is left over, not a rule of its own.
  const paletteBox = await json('__gm.overlayRect()');
  const paletteScreenH = await json('__gm.app.screen.height');
  const paletteMargin = Math.round(paletteScreenH * 0.1);
  const gapAbove = paletteBox.y;
  const gapBelow = paletteScreenH - (paletteBox.y + paletteBox.h);
  check(
    'a palette shifted up to fit keeps the tenth of the canvas below it',
    Math.abs(gapBelow - paletteMargin) <= 1 && gapAbove >= 0,
    JSON.stringify({ gapAbove, gapBelow, paletteMargin, paletteScreenH }),
  );
  await typeText('log');
  await press('Enter');
  const after13 = await graphCounts();
  s = await state();
  const newNode = s.selection?.kind === 'node' ? await nodeOf(s.selection.nodeId) : null;
  check(
    'palette adds a Log node and selects it',
    after13.nodes === before13.nodes + 1 && newNode?.type === 'Log',
    JSON.stringify({ after13, newNode }),
  );
  await shot('17-node-added');

  // 6d2. The palette ranks by how well an entry answers the query (#43): a node *named* after it
  //      comes before one that merely mentions it in its description. "variable" used to hand
  //      Enter the first row alphabetically, which was `Run behavior`.
  const beforeRank = await graphCounts();
  // A fresh spot: the Log node from 6d now sits where `bare` pointed, and whether a click there
  // hits it depends on how the layout snaps the node, not on anything this step tests.
  const bareRank = await json('__gm.graph.emptySpot()');
  await click(bareRank.x, bareRank.y, 'right');
  await typeText('variable');
  const ranked = await json('__gm.graph.paletteRows()');
  const hits = (row) => `${row.label} ${row.type}`.toLowerCase().includes('variable');
  const lastNamed = ranked.map(hits).lastIndexOf(true);
  const firstOther = ranked.map(hits).indexOf(false);
  check(
    'the palette lists the nodes named after the query first',
    lastNamed >= 0 && (firstOther === -1 || lastNamed < firstOther) && hits(ranked[0]),
    JSON.stringify(ranked),
  );
  await press('Enter');
  s = await state();
  const rankPick = s.selection?.kind === 'node' ? await nodeOf(s.selection.nodeId) : null;
  check(
    'Enter takes that node, not the one whose description mentions it',
    rankPick !== null && rankPick.type.toLowerCase().includes('variable'),
    JSON.stringify(rankPick),
  );
  await undo();
  check('undo removes it again', (await graphCounts()).nodes === beforeRank.nodes);

  // 6e. Connect: drag from the Move node's exec output onto the Log node's exec input. An
  //      exec output must not connect to a data input: dragging onto "message" does nothing.
  const fromPort = await json(`__gm.graph.portAt('n-move', 'exec', true)`);
  const toPort = await json(`__gm.graph.portAt(${JSON.stringify(newNode.id)}, 'exec', false)`);
  await drag(fromPort.x, fromPort.y, toPort.x, toPort.y, 16);
  const connected = await graphCounts();
  check(
    'dragging port to port connects the nodes',
    connected.edges === before13.edges + 1,
    JSON.stringify(connected),
  );
  const dataPort = await json(`__gm.graph.portAt(${JSON.stringify(newNode.id)}, 'message', false)`);
  await drag(fromPort.x, fromPort.y, dataPort.x, dataPort.y, 16);
  // Released on the port itself, which sits at the node's very edge: that is a drop on the node, not
  // on empty canvas. An open palette here swallows every later click – it did, for four checks.
  check(
    'incompatible ports are rejected without taking the drop for empty canvas',
    (await graphCounts()).edges === before13.edges + 1 &&
      (await state()).mode === 'edit' &&
      !(await evaluate(`__gm.locate('Search nodes…')`)),
  );
  await shot('18-connected');

  // 13d2. A drop on the node's body instead of a port: it takes the first free compatible input,
  //       and the highlight names that port while the button is still down.
  const axisX = await json(`__gm.graph.portAt('n-axis', 'x', true)`);
  const logBody = await json(`__gm.graph.nodeAt(${JSON.stringify(newNode.id)})`);
  await mouse('mouseMoved', axisX.x, axisX.y);
  await mouse('mousePressed', axisX.x, axisX.y);
  await mouse('mouseMoved', toPort.x, toPort.y, 'left', { buttons: 1 });
  await sleep(50);
  const overExec = await json(`__gm.graph.dropTarget()`);
  check('a number drag over an exec port predicts nothing', overExec === null, JSON.stringify(overExec));
  await mouse('mouseMoved', logBody.x, logBody.y, 'left', { buttons: 1 });
  await sleep(50);
  const overBody = await json(`__gm.graph.dropTarget()`);
  check(
    'over the node body it predicts the first free compatible input',
    overBody?.nodeId === newNode.id && overBody.port === 'message' && overBody.isOutput === false,
    JSON.stringify(overBody),
  );
  await shot('18b-drop-prediction');
  await mouse('mouseReleased', logBody.x, logBody.y);
  await sleep(150);
  const dropped = await graphCounts();
  const messageEdge = (await asset('mover')).graph.edges.find(
    (e) => e.to.node === newNode.id && e.to.port === 'message',
  );
  check(
    'the drop connects exactly the predicted port',
    dropped.edges === before13.edges + 2 && messageEdge?.from.port === 'x',
    JSON.stringify({ dropped, messageEdge }),
  );
  check('the prediction is dropped with the drag', (await json(`__gm.graph.dropTarget()`)) === null);
  await undo();
  check('undo removes that edge again', (await graphCounts()).edges === before13.edges + 1);

  // 13d3. Dropped into empty space, the drag opens the palette filtered to what it could reach,
  //       and the picked node arrives already wired – as one undo step.
  const empty = await json('__gm.graph.emptySpot()');
  const beforeDrop = await graphCounts();
  await mouse('mouseMoved', axisX.x, axisX.y);
  await mouse('mousePressed', axisX.x, axisX.y);
  await mouse('mouseMoved', empty.x, empty.y, 'left', { buttons: 1 });
  await sleep(50);
  await mouse('mouseReleased', empty.x, empty.y);
  await sleep(150);
  check('a drop into empty space opens the palette', Boolean(await evaluate(`__gm.locate('Search nodes…')`)));
  // "Restart game" takes exec only. Its label must not appear – and unlike "On update" it is not
  // a node on the canvas, where `locate` would find it whatever the palette lists.
  check(
    'it lists a node that takes a number, not one that cannot',
    Boolean(await evaluate(`__gm.locate('Clamp')`)) && !(await evaluate(`__gm.locate('Restart game')`)),
  );
  check(
    'the dragged edge stays on screen while the palette decides',
    (await json(`__gm.graph.danglingEdge()`)) === true,
  );
  await shot('18c-drop-into-empty');
  const clampRow = await locate('Clamp');
  await click(clampRow.x, clampRow.y);
  const afterDrop = await graphCounts();
  const wired = await state();
  const clampEdge = (await asset('mover')).graph.edges.find(
    (e) => e.from.node === 'n-axis' && e.from.port === 'x' && e.to.node === wired.selection?.nodeId,
  );
  check(
    'the new node arrives connected to its first compatible input',
    afterDrop.nodes === beforeDrop.nodes + 1 &&
      afterDrop.edges === beforeDrop.edges + 1 &&
      clampEdge?.to.port === 'value',
    JSON.stringify({ afterDrop, clampEdge }),
  );
  check(
    'and the dangling edge gives way to the real one',
    (await json(`__gm.graph.danglingEdge()`)) === false,
  );
  await undo();
  const undone = await graphCounts();
  check(
    'one undo takes back both the node and its edge',
    undone.nodes === beforeDrop.nodes && undone.edges === beforeDrop.edges,
    JSON.stringify(undone),
  );

  // Cancelling the palette has to take the dangling edge with it, or it would hang there forever.
  await mouse('mouseMoved', axisX.x, axisX.y);
  await mouse('mousePressed', axisX.x, axisX.y);
  await mouse('mouseMoved', empty.x, empty.y, 'left', { buttons: 1 });
  await mouse('mouseReleased', empty.x, empty.y);
  await sleep(150);
  await press('Escape');
  const cancelled = await graphCounts();
  check(
    'escaping the palette clears the edge and adds nothing',
    (await json(`__gm.graph.danglingEdge()`)) === false &&
      cancelled.nodes === beforeDrop.nodes &&
      cancelled.edges === beforeDrop.edges,
    JSON.stringify(cancelled),
  );

  // 6f. Delete removes the selected node together with its edge; undo brings both back.
  await select({ kind: 'node', assetId: 'mover', nodeId: newNode.id });
  check('the node inspector has no delete button of its own', !(await t.has('Delete node')));
  await press('Delete');
  const deleted = await graphCounts();
  check(
    'Delete removes the node and its edge',
    deleted.nodes === before13.nodes && deleted.edges === before13.edges,
    JSON.stringify(deleted),
  );
  await undo();
  const restored = await graphCounts();
  check(
    'undo restores node and edge',
    restored.nodes === before13.nodes + 1 && restored.edges === before13.edges + 1,
    JSON.stringify(restored),
  );

  // 6g. The fps readout runs in both modes. Play always starts on the Game tab; switching to
  //      Graph while playing shows the live highlight: hold ArrowRight → the exec edge is hot.
  const fpsEdit = await evaluate('__gm.fps()');
  check('fps readout is measured in edit mode', typeof fpsEdit === 'number' && fpsEdit > 0, `fps=${fpsEdit}`);
  check(
    'the canvas bypasses the compositor queue by default',
    (await evaluate('__gm.lowLatency()')) === true,
  );
  // Single evaluate: the readout refreshes twice a second, so read value and label together.
  check(
    'fps label is visible in the toolbar',
    (await evaluate(`!!__gm.locate(__gm.fps() + ' fps')`)) === true,
  );
  await t.play();
  check('play switches to the game tab', (await evaluate('__gm.tab()')) === 'game');
  await sleep(600);
  const fpsPlay = await evaluate('__gm.fps()');
  check(
    'fps readout keeps running in play mode',
    typeof fpsPlay === 'number' && fpsPlay > 0,
    `fps=${fpsPlay}`,
  );
  await showTab('graph');
  const holding = holdKey('ArrowRight', 300);
  await sleep(250);
  await shot('19-graph-live');
  await holding;
  await stop();

  // 6h. Variables: the "+ Variable" dropdown → Number adds "var1" with default 0; undo removes it.
  await select({ kind: 'asset', assetId: 'mover' });
  await clickText('+ Variable');
  await clickText('Number');
  check(
    'adding a variable declares it on the behavior',
    (await variableKeys()) === 'speed,var1',
    await variableKeys(),
  );
  await shot('20-variable-added');
  await undo();
  check('undo removes the variable', (await variableKeys()) === 'speed', await variableKeys());

  // 6i. The tab keeps its subject: selecting something else leaves the graph alone, and the
  //      header picker switches behaviors without any selection at all.
  const size = await graphCounts();
  const readout = `${size.nodes} nodes · ${size.edges} links`;
  check(
    'the header reports the size of the shown graph',
    Boolean(await evaluate(`__gm.locate(${JSON.stringify(readout)})`)),
    readout,
  );
  check('the header has no Add node button – the right-click palette is the way', !(await find('Add node…')));
  await select(null);
  check(
    'graph editor keeps its behavior when nothing is selected',
    (await evaluate(`__gm.graph.current()`)) === 'mover',
  );
  await select({ kind: 'asset', assetId: 'cam' });
  check(
    'graph editor keeps its behavior for a non-behavior asset',
    (await evaluate(`__gm.graph.current()`)) === 'mover',
  );
  await select({ kind: 'asset', assetId: 'spawner' });
  check(
    'selecting another behavior leaves the tab on its own (#171)',
    (await evaluate(`__gm.graph.current()`)) === 'mover',
  );
  await evaluate(`__gm.state.openAsset('spawner')`);
  const twoOpen = await json('__gm.documents()');
  check(
    'opening it brings it up in a tab of its own',
    (await evaluate(`__gm.graph.current()`)) === 'spawner' &&
      twoOpen.active === 'asset:spawner' &&
      twoOpen.docs.includes('asset:mover'),
    JSON.stringify(twoOpen),
  );
  await evaluate(`__gm.closeDocument('asset:spawner')`);
  check(
    'closing it shows the behavior next to it again',
    (await evaluate(`__gm.graph.current()`)) === 'mover' && (await json('__gm.tab()')) === 'graph',
    String(await evaluate(`__gm.graph.current()`)),
  );
  await select({ kind: 'asset', assetId: 'mover' });

  // 6j. Mouse behaviour, as in the scene view: the middle button pans from anywhere – a node
  //      under it included – and the left button no longer pans at all.
  await clickText('Fit');
  const positions = async () =>
    (await asset('mover')).graph.nodes.map((n) => `${n.id}:${n.x},${n.y}`).join(' ');
  const area = await json('__gm.graph.canvasRect()');
  const before13i = await positions();
  const axisScreenBefore = await json(`__gm.graph.nodeAt('n-axis')`);
  await drag(axisScreenBefore.x, axisScreenBefore.y, axisScreenBefore.x + 120, axisScreenBefore.y + 60, {
    button: 'middle',
  });
  const axisScreenPanned = await json(`__gm.graph.nodeAt('n-axis')`);
  check(
    'the middle button pans even when it starts on a node',
    Math.abs(axisScreenPanned.x - axisScreenBefore.x - 120) < 3 &&
      Math.abs(axisScreenPanned.y - axisScreenBefore.y - 60) < 3,
    JSON.stringify({ axisScreenBefore, axisScreenPanned }),
  );
  check(
    'panning over a node leaves the node where it was',
    (await positions()) === before13i,
    await positions(),
  );

  // Fit again: the pan just now pushed a node out of view, and a band takes only what it sees.
  await clickText('Fit');
  // An empty spot: after a fit every node sits at least a margin away from the corner.
  const corner = { x: area.x + 6, y: area.y + 6 };
  const opposite = { x: area.x + area.w - 6, y: area.y + area.h - 6 };
  const axisBeforeBand = await json(`__gm.graph.nodeAt('n-axis')`);
  await drag(corner.x, corner.y, corner.x + 60, corner.y + 40);
  const axisAfterBand = await json(`__gm.graph.nodeAt('n-axis')`);
  check(
    'dragging with the left button no longer pans',
    Math.abs(axisAfterBand.x - axisBeforeBand.x) < 3 && Math.abs(axisAfterBand.y - axisBeforeBand.y) < 3,
    JSON.stringify({ axisBeforeBand, axisAfterBand }),
  );

  // 6k. A rubber band across the whole canvas takes every node – the count comes from the model,
  //      so this cannot agree with the canvas by sharing its rule.
  const nodeCount = (await asset('mover')).graph.nodes.length;
  await drag(corner.x, corner.y, opposite.x, opposite.y, { steps: 16 });
  const banded = await json('__gm.graph.selected()');
  check(
    'a rubber band selects every node it spans',
    banded.length === nodeCount,
    `${banded.length} of ${nodeCount}`,
  );
  await shot('21-graph-multiselect');

  // 6l. The whole selection moves as one, and one undo takes all of it back.
  const beforeMove = (await asset('mover')).graph.nodes.map((n) => ({ id: n.id, x: n.x, y: n.y }));
  const grabAt = await json(`__gm.graph.nodeAt('n-axis')`);
  // Screen pixels become graph units through the zoom, which the fit picks from the canvas size.
  const units = async (px) => px / Number(await evaluate('__gm.graph.zoom()'));
  const [mx, my] = [await units(40), await units(30)];
  await drag(grabAt.x, grabAt.y, grabAt.x + 40, grabAt.y + 30);
  const afterMove = await asset('mover');
  const movedTogether = beforeMove.every((n) => {
    const now = afterMove.graph.nodes.find((m) => m.id === n.id);
    return Math.abs(now.x - (n.x + mx)) <= 2 && Math.abs(now.y - (n.y + my)) <= 2;
  });
  check('dragging one of them moves the whole selection', movedTogether, await positions());
  await undo();
  check('one undo takes the group move back', (await positions()) === before13i, await positions());

  // 13k2. Grid snapping. Distances are stated in graph units, which `units()` reads off the
  //       current zoom – the canvas is not wide enough here for a zoom of 1.
  const GRID = 24;
  const onGrid = (n) => n.x % GRID === 0 && n.y % GRID === 0;
  check('snapping is off until it is asked for', (await json('__gm.graph.snapping()')) === false);
  // The switch is a magnet (#194): a square icon button that stays lit while snapping is on.
  const magnet = await json('__gm.graph.snapButton()');
  await click(magnet.x, magnet.y);
  check(
    'the toggle switches it on without moving a single node',
    (await json('__gm.graph.snapping()')) === true && (await positions()) === before13i,
    await positions(),
  );
  const magnetOn = await json('__gm.graph.snapButton()');
  check(
    'the magnet is a square icon without a caption, and lit while on',
    magnetOn.toggled && magnetOn.w === magnetOn.h && (await json(`__gm.locate('Snap')`)) === null,
    JSON.stringify(magnetOn),
  );

  // A single node: dropped between two grid lines, it lands on the nearer one.
  await click(corner.x, corner.y);
  const snapPre = await nodeOf('n-axis');
  const snapFrom = await json(`__gm.graph.nodeAt('n-axis')`);
  const snapBy = await units(50);
  await drag(snapFrom.x, snapFrom.y, snapFrom.x + 50, snapFrom.y + 50);
  const snapped = await nodeOf('n-axis');
  check(
    'a dragged node lands on the grid, not where the pointer let go',
    onGrid(snapped) &&
      Math.abs(snapped.x - (snapPre.x + snapBy)) <= GRID / 2 &&
      Math.abs(snapped.y - (snapPre.y + snapBy)) <= GRID / 2,
    `${snapPre.x},${snapPre.y} → ${snapped.x},${snapped.y}`,
  );
  const others = (await asset('mover')).graph.nodes.filter((n) => n.id !== 'n-axis');
  check(
    'the nodes it was dragged past stay off the grid',
    others.some((n) => !onGrid(n)),
    JSON.stringify(others.map((n) => `${n.id}:${n.x},${n.y}`)),
  );

  // A group: every selected node snaps for itself, so the whole selection ends up on grid lines
  // – off-grid gaps inside it close, rather than travelling along.
  await drag(corner.x, corner.y, opposite.x, opposite.y, { steps: 16 });
  const groupPre = (await asset('mover')).graph.nodes.map((n) => ({ id: n.id, x: n.x, y: n.y }));
  check(
    'the selection is not on the grid yet',
    groupPre.some((n) => !onGrid(n)),
    JSON.stringify(groupPre.map((n) => `${n.id}:${n.x},${n.y}`)),
  );
  const grabFrom = await json(`__gm.graph.nodeAt('n-axis')`);
  const groupBy = await units(30);
  await drag(grabFrom.x, grabFrom.y, grabFrom.x + 30, grabFrom.y + 30);
  const groupPost = (await asset('mover')).graph.nodes;
  check(
    'every selected node lines up on the grid for itself, none by more than half a step',
    groupPost.every(onGrid) &&
      groupPre.every((n) => {
        const now = groupPost.find((m) => m.id === n.id);
        return Math.abs(now.x - (n.x + groupBy)) <= GRID / 2 && Math.abs(now.y - (n.y + groupBy)) <= GRID / 2;
      }),
    await positions(),
  );
  await undo();
  await undo();
  check('undo takes both snapped moves back', (await positions()) === before13i, await positions());

  // Switching it off has to give the pointer its exact drop position back.
  await click(magnet.x, magnet.y);
  await click(corner.x, corner.y);
  const offPre = await nodeOf('n-axis');
  const offFrom = await json(`__gm.graph.nodeAt('n-axis')`);
  const offBy = await units(50);
  await drag(offFrom.x, offFrom.y, offFrom.x + 50, offFrom.y + 50);
  const offPost = await nodeOf('n-axis');
  check(
    'switched off, a node lands where it was dropped again, off the grid',
    (await json('__gm.graph.snapping()')) === false &&
      !onGrid(offPost) &&
      Math.abs(offPost.x - (offPre.x + offBy)) <= 2 &&
      Math.abs(offPost.y - (offPre.y + offBy)) <= 2,
    `${offPre.x},${offPre.y} → ${offPost.x},${offPost.y}`,
  );
  await undo();

  // 6m. Delete acts on the selection, not just the primary node.
  await drag(corner.x, corner.y, opposite.x, opposite.y, { steps: 16 });
  const beforeDelete = await graphCounts();
  await press('Delete');
  const afterDelete = await graphCounts();
  check(
    'Delete removes every selected node, edges with them',
    afterDelete.nodes === 0 && afterDelete.edges === 0,
    JSON.stringify(afterDelete),
  );
  await undo();
  const restoredAll = await graphCounts();
  check(
    'one undo brings the whole graph back',
    restoredAll.nodes === beforeDelete.nodes && restoredAll.edges === beforeDelete.edges,
    JSON.stringify(restoredAll),
  );

  // 6n. Ctrl-click adds and removes single nodes. Fit first, so every node is really on screen
  //      and a click cannot miss one that the earlier pan pushed over the edge.
  await select({ kind: 'asset', assetId: 'mover' });
  await clickText('Fit');
  const axisRow = await json(`__gm.graph.nodeAt('n-axis')`);
  await click(axisRow.x, axisRow.y);
  const second = (await asset('mover')).graph.nodes.find((n) => n.id !== 'n-axis');
  const secondAt = await json(`__gm.graph.nodeAt(${JSON.stringify(second.id)})`);
  await click(secondAt.x, secondAt.y, 'left', { ctrl: true });
  check(
    'ctrl-click adds a second node to the selection',
    JSON.stringify(await json('__gm.graph.selected()')) === JSON.stringify(['n-axis', second.id]),
    JSON.stringify(await json('__gm.graph.selected()')),
  );
  await click(secondAt.x, secondAt.y, 'left', { ctrl: true });
  check(
    'ctrl-clicking it again removes it',
    JSON.stringify(await json('__gm.graph.selected()')) === JSON.stringify(['n-axis']),
    JSON.stringify(await json('__gm.graph.selected()')),
  );

  // 6o. Fit really fits: proven against a node parked far outside, and against the fact that the
  //      graph is then wider than the canvas – otherwise centring alone would pass this check.
  // The distance follows the canvas: a fixed 2500 units needs a zoom below the 0.25 floor once
  // the canvas is short, and then Fit cannot fit anything however correct it is.
  const park = Math.round(area.w);
  await evaluate(
    `(() => { const n = __gm.state.project.assets.find(a => a.id === 'mover').graph.nodes.find(n => n.id === 'n-axis'); n.x += ${park}; __gm.state.preview(); })()`,
  );
  await sleep(250);
  await clickText('Fit');
  const rects = [];
  for (const node of (await asset('mover')).graph.nodes)
    rects.push(await json(`__gm.graph.nodeRect(${JSON.stringify(node.id)})`));
  const span = Math.max(...rects.map((r) => r.x + r.w)) - Math.min(...rects.map((r) => r.x));
  check(
    'the parked node makes the graph wider than the canvas, so fitting has to zoom out',
    span > area.w * 0.5,
    `span=${Math.round(span)} canvas=${Math.round(area.w)}`,
  );
  const outside = rects.filter(
    (r) => r.x < area.x || r.y < area.y || r.x + r.w > area.x + area.w || r.y + r.h > area.y + area.h,
  );
  check(
    'Fit leaves no node hanging out of the view',
    outside.length === 0,
    `${outside.length} outside: ${JSON.stringify(outside.slice(0, 2))}`,
  );
  await shot('22-graph-fitted');
  await evaluate(
    `(() => { const n = __gm.state.project.assets.find(a => a.id === 'mover').graph.nodes.find(n => n.id === 'n-axis'); n.x -= ${park}; __gm.state.preview(); })()`,
  );
  await clickText('Fit');
  check('the parked node is back where it started', (await positions()) === before13i, await positions());

  // 6p. Hiding a link: it stops being drawn across the graph but keeps carrying its value, and
  //      comes back while either of its two nodes is selected.
  await select({ kind: 'asset', assetId: 'mover' });
  await clickText('Fit');
  const allEdges = (await asset('mover')).graph.edges;
  const edge = allEdges.find((e) => e.from.port !== 'exec') ?? allEdges[0];
  const id = JSON.stringify(edge.id);
  const drawn = async () => await json(`__gm.graph.edgeDrawn(${id})`);
  const edgeNow = async () => (await asset('mover')).graph.edges.find((e) => e.id === edge.id);
  check('the link is drawn as a curve to start with', (await drawn()) === true);

  const outPort = await json(
    `__gm.graph.portAt(${JSON.stringify(edge.from.node)}, ${JSON.stringify(edge.from.port)}, true)`,
  );
  await click(outPort.x, outPort.y, 'right');
  check('right-clicking a port offers hiding its link', Boolean(await evaluate(`__gm.locate('Hide link')`)));
  await clickText('Hide link');
  await select({ kind: 'asset', assetId: 'mover' });
  const hidden = await edgeNow();
  check(
    'hiding changes nothing but a flag – the connection is still there',
    Boolean(hidden) &&
      hidden.folded === true &&
      hidden.from.node === edge.from.node &&
      hidden.to.node === edge.to.node,
    JSON.stringify(hidden),
  );
  check('and the curve is gone from the canvas', (await drawn()) === false);
  const mark = await json(`__gm.graph.foldMark(${id}, true)`);
  check(
    'a stub with a mark takes its place at the port',
    mark !== null && Math.abs(mark.x - outPort.x) < 40 && Math.abs(mark.y - outPort.y) < 8,
    JSON.stringify({ mark, outPort }),
  );
  await shot('23-link-hidden');

  // Selecting either end lends the curve back – the source first, then the target.
  const sourceAt = await json(`__gm.graph.nodeAt(${JSON.stringify(edge.from.node)})`);
  await click(sourceAt.x, sourceAt.y);
  check('selecting the node at one end brings the curve back', (await drawn()) === true);
  const targetAt = await json(`__gm.graph.nodeAt(${JSON.stringify(edge.to.node)})`);
  await click(targetAt.x, targetAt.y);
  check('selecting the node at the other end does too', (await drawn()) === true);
  await select({ kind: 'asset', assetId: 'mover' });
  check('deselecting hides it again', (await drawn()) === false);

  // The mark is the handle: clicking it selects the node at the far end, which is also what
  // puts the curve back – so it answers "where does this go?" in one click.
  const mark2 = await json(`__gm.graph.foldMark(${id}, true)`);
  await click(mark2.x, mark2.y);
  check(
    'clicking the mark jumps to the node at the far end',
    JSON.stringify(await json('__gm.graph.selected()')) === JSON.stringify([edge.to.node]),
    JSON.stringify(await json('__gm.graph.selected()')),
  );
  check('which shows the curve again', (await drawn()) === true);

  await undo();
  await select({ kind: 'asset', assetId: 'mover' });
  const shown = await edgeNow();
  check(
    'undo unhides the link, with nothing left behind',
    shown.folded === undefined && (await drawn()) === true,
    JSON.stringify(shown),
  );

  // 6q. Two hidden links out of one port. Drawn per link they would stack stub, dot and name on
  //      the very same pixels – the names smearing over each other. One port, one mark.
  const before13p = await graphCounts();
  const forkPort = await json(
    `__gm.graph.portAt(${JSON.stringify(edge.from.node)}, ${JSON.stringify(edge.from.port)}, true)`,
  );
  // A spot no node covers, measured rather than guessed: after the Fit above, where the nodes
  // sit on screen is not something this step gets to assume.
  const canvasArea = await json('__gm.graph.canvasRect()');
  const taken = [];
  for (const node of (await asset('mover')).graph.nodes)
    taken.push(await json(`__gm.graph.nodeRect(${JSON.stringify(node.id)})`));
  const freeSpots = [
    { x: canvasArea.x + 60, y: canvasArea.y + canvasArea.h - 60 },
    { x: canvasArea.x + canvasArea.w - 60, y: canvasArea.y + canvasArea.h - 60 },
    { x: canvasArea.x + 60, y: canvasArea.y + 60 },
  ];
  const free =
    freeSpots.find((p) =>
      taken.every(
        (r) => !r || p.x < r.x - 10 || p.y < r.y - 10 || p.x > r.x + r.w + 10 || p.y > r.y + r.h + 10,
      ),
    ) ?? freeSpots[0];
  // The same gesture as 13d3: dropped into empty space the palette offers only what this port can
  // reach, and the picked node arrives already wired – so no port name has to be guessed here.
  await mouse('mouseMoved', forkPort.x, forkPort.y);
  await mouse('mousePressed', forkPort.x, forkPort.y);
  await mouse('mouseMoved', free.x, free.y, 'left', { buttons: 1 });
  await sleep(50);
  await mouse('mouseReleased', free.x, free.y);
  await sleep(200);
  const forkRow = await locate('Clamp');
  if (forkRow) await click(forkRow.x, forkRow.y);
  await sleep(250);
  const twin = (await state()).selection?.nodeId;
  const forked = (await asset('mover')).graph.edges.filter(
    (e) => e.from.node === edge.from.node && e.from.port === edge.from.port,
  );
  check(
    'a second link now leaves the same port',
    forked.length === 2 && (await graphCounts()).nodes === before13p.nodes + 1,
    JSON.stringify({ forked: forked.length, twin, free, row: Boolean(forkRow) }),
  );

  await click(forkPort.x, forkPort.y, 'right');
  check('the port menu counts what it would hide', Boolean(await evaluate(`__gm.locate('Hide 2 links')`)));
  await clickText('Hide 2 links');
  await select({ kind: 'asset', assetId: 'mover' });
  const ids = forked.map((e) => JSON.stringify(e.id));
  const markA = await json(`__gm.graph.foldMark(${ids[0]}, true)`);
  const markB = await json(`__gm.graph.foldMark(${ids[1]}, true)`);
  check(
    'both hidden links share one mark at the port instead of stacking two',
    markA !== null && markA.x === markB.x && markA.y === markB.y && markA.links === 2,
    JSON.stringify({ markA, markB }),
  );
  const marks = await json(`__gm.graph.foldMarks()`);
  check(
    'and only three marks are drawn for the two links: one shared, one at each far end',
    marks.length === 3 && marks.filter((m) => m.links === 2).length === 1,
    JSON.stringify(marks),
  );
  check(
    'the shared mark names one far node and counts the rest',
    markA.label.endsWith('+1') && markA.label.length > 2,
    JSON.stringify(markA.label),
  );
  await shot('24-links-bundled');

  // The bundled mark is still a handle: one click selects every far end, which is also what
  // lends all of its curves back at once.
  await click(markA.x, markA.y);
  const picked = await json('__gm.graph.selected()');
  check(
    'clicking a bundled mark selects every node the port feeds',
    picked.length === 2 && picked.includes(edge.to.node) && picked.includes(twin),
    JSON.stringify(picked),
  );
  check(
    'and both curves come back at once',
    (await json(`__gm.graph.edgeDrawn(${ids[0]})`)) === true &&
      (await json(`__gm.graph.edgeDrawn(${ids[1]})`)) === true,
  );

  await click(markA.x, markA.y, 'right');
  check(
    'the mark menu shows both links back in one go',
    Boolean(await evaluate(`__gm.locate('Show 2 links')`)),
  );
  await clickText('Show 2 links');
  await select({ kind: 'asset', assetId: 'mover' });
  const unfolded = (await asset('mover')).graph.edges.filter(
    (e) => e.from.node === edge.from.node && e.from.port === edge.from.port,
  );
  check(
    'showing them again leaves no fold behind',
    unfolded.every((e) => e.folded === undefined) && (await json(`__gm.graph.foldMarks()`)).length === 0,
    JSON.stringify(unfolded),
  );
  // One step of undo takes both back – hiding two links was one command, so it is one undo.
  await undo();
  await select({ kind: 'asset', assetId: 'mover' });
  const refolded = (await asset('mover')).graph.edges.filter(
    (e) => e.from.node === edge.from.node && e.from.port === edge.from.port,
  );
  check(
    'and undo re-hides both as one step',
    refolded.length === 2 && refolded.every((e) => e.folded === true),
    JSON.stringify(refolded.map((e) => e.folded)),
  );
  await undo();

  const forkedNow = async () =>
    (await asset('mover')).graph.edges.filter(
      (e) => e.from.node === edge.from.node && e.from.port === edge.from.port,
    ).length;
  const portNow = await json(
    `__gm.graph.portAt(${JSON.stringify(edge.from.node)}, ${JSON.stringify(edge.from.port)}, true)`,
  );
  await click(portNow.x, portNow.y, 'right');
  const offered = await find('Disconnect 2 links');
  if (offered) await click(offered.x, offered.y);
  await sleep(250);
  const cut = await forkedNow();
  await undo();
  check(
    'disconnecting both links at a port is one undo step',
    Boolean(offered) && cut === 0 && (await forkedNow()) === 2,
    JSON.stringify({ offered: Boolean(offered), cut, after: await forkedNow() }),
  );

  // 6r. Collapsing a node: the title bar alone, every link meeting at one point per side. No new
  //      link lands on it until it is expanded, and the state is saved with the project.
  await select({ kind: 'asset', assetId: 'mover' });
  await clickText('Fit');
  const edgesBefore13q = (await graphCounts()).edges;
  const openRect = await json(`__gm.graph.nodeRect('n-move')`);
  const chevron = await json(`__gm.graph.chevronAt('n-move')`);
  await click(chevron.x, chevron.y);
  const shut = await json(`__gm.graph.nodeRect('n-move')`);
  const zoom = openRect.w / 176;
  check(
    'the chevron collapses the node to its title bar, and leaves the selection alone',
    (await nodeOf('n-move')).collapsed === true &&
      Math.abs(shut.h - 24 * zoom) < 1 &&
      (await json('__gm.graph.selected()')).length === 0,
    JSON.stringify({ openRect, shut, collapsed: (await nodeOf('n-move')).collapsed }),
  );
  // Title starts 20 units in and ends 11 before the edge; `locate` matches exactly, so a cut title is null.
  const titleText = await json(`__gm.locate('Move')`);
  check(
    'a collapsed node narrows to its whole title, keeping its left edge under the chevron',
    titleText !== null &&
      Math.abs(shut.x - openRect.x) < 1 &&
      shut.w < openRect.w &&
      Math.abs(shut.w - (2 * (titleText.x - shut.x) - 9 * zoom)) < 2,
    JSON.stringify({ openRect, shut, titleText }),
  );
  const title = await json(`__gm.graph.nodeAt('n-move')`);
  const anchorOf = (port, out) => json(`__gm.graph.portAt('n-move', '${port}', ${out})`);
  const inputs = [
    await anchorOf('exec', false),
    await anchorOf('object', false),
    await anchorOf('dy', false),
  ];
  const output = await anchorOf('exec', true);
  check(
    'every link meets at one point per side, level with the title',
    inputs.every((p) => Math.abs(p.x - shut.x) < 1 && Math.abs(p.y - title.y) < 1) &&
      Math.abs(output.x - (shut.x + shut.w)) < 1 &&
      Math.abs(output.y - title.y) < 1,
    JSON.stringify({ inputs, output, title, shut }),
  );
  check(
    'the links are still there and still drawn',
    (await graphCounts()).edges === edgesBefore13q && (await json(`__gm.graph.edgeDrawn('e3')`)) === true,
  );
  await shot('24b-node-collapsed');

  const speedOut = await json(`__gm.graph.portAt('n-speed', 'speed', true)`);
  await mouse('mouseMoved', speedOut.x, speedOut.y);
  await mouse('mousePressed', speedOut.x, speedOut.y);
  await mouse('mouseMoved', title.x, title.y, 'left', { buttons: 1 });
  await sleep(50);
  const aimed = await json('__gm.graph.dropTarget()');
  await mouse('mouseReleased', title.x, title.y);
  await sleep(150);
  await press('Escape');
  check(
    'a link dropped on a collapsed node goes nowhere',
    aimed === null && (await graphCounts()).edges === edgesBefore13q,
    JSON.stringify(aimed),
  );

  for (const port of ['x', 'y']) {
    const at = await json(`__gm.graph.portAt('n-axis', '${port}', true)`);
    await click(at.x, at.y, 'right');
    await clickText('Hide link');
  }
  await select({ kind: 'asset', assetId: 'mover' });
  const markDx = await json(`__gm.graph.foldMark('e3', false)`);
  const markDy = await json(`__gm.graph.foldMark('e4', false)`);
  check(
    'hidden links into a collapsed node share one mark instead of stacking',
    markDx !== null && markDx.x === markDy.x && markDx.y === markDy.y && markDx.links === 2,
    JSON.stringify({ markDx, markDy }),
  );
  await undo();
  await undo();

  await select({ kind: 'node', assetId: 'mover', nodeId: 'n-move', nodeIds: ['n-speed', 'n-move'] });
  await click(title.x, title.y, 'right');
  check(
    'a mixed selection is offered both ways',
    Boolean(await evaluate(`__gm.locate('Collapse node', false)`)) &&
      Boolean(await evaluate(`__gm.locate('Expand node', false)`)),
  );
  await press('Escape');
  await undo();
  check('undo expands it again', (await nodeOf('n-move')).collapsed === undefined);

  await select({ kind: 'node', assetId: 'mover', nodeId: 'n-move', nodeIds: ['n-speed', 'n-move'] });
  const openTitle = await json(`__gm.graph.nodeAt('n-move')`);
  await click(openTitle.x, openTitle.y, 'right');
  const collapseBoth = await json(`__gm.locate('Collapse 2 nodes', false)`);
  check('two expanded nodes are offered as one', collapseBoth !== null);
  if (collapseBoth) await click(collapseBoth.x, collapseBoth.y);
  else await press('Escape');
  await sleep(200);
  const both = async () => [(await nodeOf('n-speed')).collapsed, (await nodeOf('n-move')).collapsed];
  check('the menu collapses the whole selection', JSON.stringify(await both()) === '[true,true]');
  await undo();
  check(
    'and one undo takes all of it back',
    JSON.stringify(await both()) === '[null,null]',
    JSON.stringify(await both()),
  );

  // Saved and loaded: a reload, not just the file, because the drawing is what has to come back.
  await select({ kind: 'asset', assetId: 'mover' });
  const again = await json(`__gm.graph.chevronAt('n-move')`);
  await click(again.x, again.y);
  const savedMove = async () => {
    await saved();
    const doc = await api(`projects/${projectId}`);
    return doc.project.assets.find((a) => a.id === 'mover').graph.nodes.find((n) => n.id === 'n-move');
  };
  check('the collapse reaches the saved file', (await savedMove()).collapsed === true);
  await navigate();
  await sleep(500);
  await select({ kind: 'asset', assetId: 'mover' });
  await showTab('graph');
  const reloaded = await json(`__gm.graph.nodeRect('n-move')`);
  check(
    'and a reloaded project draws it collapsed again',
    (await nodeOf('n-move')).collapsed === true && Math.abs(reloaded.h / reloaded.w - shut.h / shut.w) < 0.01,
    JSON.stringify(reloaded),
  );
  const reopen = await json(`__gm.graph.chevronAt('n-move')`);
  await click(reopen.x, reopen.y);
  check('expanding leaves no trace in the file', !('collapsed' in (await savedMove())));

  // 6z. Ports carrying one value (#207): the output takes the type both inputs agree on, the
  //     inputs stay open for everything, and an edge the new type breaks is drawn as broken.
  await mutate(`
    const p = __gm.state.project;
    p.assets.push({
      id: 'picky',
      type: 'behavior',
      name: 'Picky',
      props: { enabled: true, runInEditor: false },
      variables: [],
      graph: {
        nodes: [
          { id: 'p-a', type: 'Number', x: 0, y: 0, params: { value: 1 } },
          { id: 'p-b', type: 'Number', x: 0, y: 150, params: { value: 2 } },
          { id: 'p-text', type: 'String', x: 0, y: 300, params: { value: 'hi' } },
          { id: 'p-pick', type: 'FirstNotEmpty', x: 300, y: 60, params: {} },
          { id: 'p-sub', type: 'Substring', x: 600, y: 60, params: {} },
        ],
        edges: [],
      },
    });
    __gm.state.select({ kind: 'asset', assetId: 'picky' });
  `);
  await showTab('graph');
  const pickTypes = async () => json(`__gm.graph.portTypes('p-pick')`);
  check(
    'a group with nothing plugged in stays any',
    (await pickTypes()).outputs.value === 'any',
    JSON.stringify(await pickTypes()),
  );

  const wire = async (fromNode, fromPort, toNode, toPort) => {
    const from = await json(
      `__gm.graph.portAt(${JSON.stringify(fromNode)}, ${JSON.stringify(fromPort)}, true)`,
    );
    const to = await json(`__gm.graph.portAt(${JSON.stringify(toNode)}, ${JSON.stringify(toPort)}, false)`);
    await drag(from.x, from.y, to.x, to.y, 16);
  };
  // Laid while the output is still any, so a number later makes it a text input fed by a number.
  await wire('p-pick', 'value', 'p-sub', 'text');
  const toSub = async () => (await asset('picky')).graph.edges.find((e) => e.to.node === 'p-sub');
  const outEdge = await toSub();
  const edgeColor = async () => json(`__gm.graph.edgeColor(${JSON.stringify(outEdge?.id ?? '')})`);
  const danger = await json(`__gm.themeColor('danger')`);
  check(
    'an any output connects to a text input and is drawn as a working link',
    outEdge !== undefined && (await edgeColor()) !== danger,
    JSON.stringify({ edge: Boolean(outEdge), color: await edgeColor(), danger }),
  );

  await wire('p-a', 'value', 'p-pick', 'a');
  check(
    'one input alone says nothing: the other could still become anything',
    (await pickTypes()).outputs.value === 'any',
    JSON.stringify(await pickTypes()),
  );

  await wire('p-b', 'value', 'p-pick', 'b');
  const typed = await pickTypes();
  check(
    'with both inputs on a number the output is a number, the inputs stay any',
    typed.outputs.value === 'number' && typed.inputs.a === 'any' && typed.inputs.b === 'any',
    JSON.stringify(typed),
  );
  check(
    'both input pins are painted as the number that flows in, though their type is any',
    typed.paint.a === 'number' && typed.paint.b === 'number',
    JSON.stringify(typed),
  );
  check(
    'the edge the new type breaks stays and is drawn in the danger colour',
    (await toSub()) !== undefined && (await edgeColor()) === danger,
    JSON.stringify({ color: await edgeColor(), danger }),
  );

  await shot('19-shared-port-types');

  // An input that keeps its `any` is one that can be re-plugged without unplugging first.
  await wire('p-text', 'value', 'p-pick', 'a');
  const mixed = await pickTypes();
  check(
    'a connected input takes another type, and the group opens up again',
    mixed.outputs.value === 'any' && (await edgeColor()) !== danger,
    JSON.stringify({ types: mixed, color: await edgeColor() }),
  );
  check(
    'inputs fed by different types are painted apart, which is why the output says nothing',
    mixed.paint.a === 'string' && mixed.paint.b === 'number' && mixed.inputs.a === 'any',
    JSON.stringify(mixed),
  );
  // Read off the canvas: the colour is on the pin, not only in the definition.
  const pinPixel = async (port) => {
    const at = await json(`__gm.graph.portAt('p-pick', ${JSON.stringify(port)}, false)`);
    return json(`__gm.pixelAt(${Math.round(at.x)}, ${Math.round(at.y)})`);
  };
  const pinColors = { a: await pinPixel('a'), b: await pinPixel('b') };
  const wanted = {
    a: await json(`__gm.themeColor('portString')`),
    b: await json(`__gm.themeColor('portNumber')`),
  };
  check(
    'the two pins are drawn in those two colours',
    pinColors.a === wanted.a && pinColors.b === wanted.b,
    JSON.stringify({ pinColors, wanted }),
  );
  await shot('20-input-pin-colours');
  await mutate(`
    const p = __gm.state.project;
    p.assets = p.assets.filter((a) => a.id !== 'picky');
    __gm.state.select({ kind: 'asset', assetId: 'mover' });
  `);

  await showTab('scene');
}