Force-directed graph · qwen3.8-flash

Let me start by looking at the current directory.

Let me build the app.

Plan:
- 40 nodes, ids 0-39, 4 clusters of 10 (0-9, 10-19, 20-29, 30-39).
- Within each cluster, ring connections: node i to i+1 within cluster (wrap-around).
- Connect nodes 0, 10, 20, 30 in a ring to link clusters.
- D3 force simulation.
- SVG with zoom/pan via d3.zoom on svg, applied to a `g` container.
- Drag via d3.drag on node groups.
- Hover highlighting with adjacency map.
- Reset view button: transitions zoom transform to initial transform.
- Keep initial graph in view: fit scale computed from extent, or set initial transform.

Careful: dragging background pans — d3.zoom on svg, and drag on nodes stops propagation.

Let me write the file and test with the browser tool.

Design considerations: Use viewport 1200x800 in browser inspection. Make SVG responsive to window size.

Initial framing: compute a transform that centers the graph. Simplest: run the simulation, and nodes initialized in a circle around center. Use forceCenter(width/2, height/2) so the graph stays within view. Then reset view = zoom to identity transform (or fitted transform).

Better: pre-warm the simulation (run ticks headless) so the layout is settled at start, then compute a fit transform to the node extent with padding, and apply it as the initial transform. Reset view re-computes/reapplies that stored initial transform.

Let me implement:

```js
const svg = d3.select("#chart");
const g = svg.append("g"); // zoomable
let transformInitial;

function fitTransform(){ ... }
```

Use d3.zoomIdentity.translate(...).scale(k). Apply via svg.call(zoom.transform, t).

Also handle window resize.

Hover: highlight node, neighbors, links between them (links connecting the hovered node to neighbors). "its directly connected neighbors, and their connecting links" — links from hovered node to neighbors. Dim others.

Add a tooltip maybe. Keep it nice looking.

Let me write the code.

Also stats/legend showing clusters.

Implementation details for drag: on "start" -> if(!event.active) simulation.alphaTarget(0.3).restart(); event.subject.fx = ... Node groups need to be bound to simulation node data. Standard approach: nodes = simulation.nodes() data; drag on node selection with .subject.

Since zoom applies transform to `g`, and drag events give event.x/event.y in the local coordinate system of the element being dragged when using d3.drag with the container set correctly. d3.drag uses the container's coordinate system — by default the container is the parent node of the element (for SVG elements, the ownerSVGElement... actually default container accessor is: `function() { return this.parentNode; }` for SVG elements? The default is:

```js
function defaultContainer() {
  return this.parentNode;
}
```

Yes, d3-drag's default container is `this.parentNode`, so with node groups inside `g.zoomable`, pointer coords are computed in the parent's coordinate space which accounts for the zoom transform. Good — event.x/event.y will be in simulation space.

Note: d3.drag's default container returns parentNode, and it uses `d3.pointer(event, container)` — that inverse-transforms correctly through SVG transforms. Good.

Also need to stop zoom from panning when dragging a node: d3.drag calls stopPropagation? d3-drag does `event.stopPropagation()` in its mousedowned handler by default? Yes — d3.drag's mousedowned calls `event.stopImmediatePropagation()`? Actually d3-drag does: `noevent(event)` which calls event.stopImmediatePropagation() and event.preventDefault() unless configured. Hmm, d3-drag's `mousedowned` does `nopropagation(event)` — yes, it stops propagation. And zoom's mousedown handler is on svg; since drag's handler on the node element stops propagation before bubbling, zoom won't start. But zoom also listens on mousedown in capture? d3-zoom listens with `on("mousedown.zoom")` bubbling phase. So drag's stopPropagation prevents zoom. Good.

But d3-zoom also filters on wheel events anywhere; fine.

Also zoom's dblclick would zoom in; keep it, or disable. I'll disable dblclick zoom maybe keep default. Keep default is fine but maybe reset uses transition. I'll leave dblclick.zoom on.

Touch support: not needed.

Also "release lets the simulation settle" — on drag end, fx=fy=null, alphaTarget(0).

Let's write the file. I'll add nice styling: dark background, glow, legend, labels.

Arrow-less links with stroke width by ... just constant.

Initial positions: place cluster nodes in 4 clusters arranged around center to help layout. Pre-run 200 ticks before rendering, then fit. Then set simulation alpha low.

Let me write it.

Also labels: text inside node group, showing id, centered, font-size ~ node radius. Nodes radius maybe 12 for hubs (0,10,20,30) and 8 for others.

Let me write code:

```js
const N = 40, CLUSTERS = 4, PER = 10;
const palette = ["#ff6b6b"...]
```

Use d3.scaleOrdinal with d3.schemeTableau10? Available in d3 bundle (d3-scale-chromatic) — global d3 build includes schemeCategory10 typically. Full d3.min.js includes it. But to be safe I'll hardcode colors.

Let me check the d3 file quickly to confirm it's the full bundle.

Let me write the file now.

Reset view: `svg.transition().duration(600).call(zoom.transform, initialTransform)`.

Resize: recompute? Simple: keep initial transform based on original size; on resize, update fit. I'll recompute the fit transform on resize and update the svg's viewBox/width.

I'll use a fixed logical size for the simulation (e.g., width/height of container measured at load), plus forceCenter.

Approach: 
- measureW/H = client size of #chart.
- simulation forces: link, charge, center at (w/2, h/2), collide.
- After pre-ticking, compute fit transform via extent of node positions with padding 40; k = min(2, ...). Store as initialTransform.
- Apply it.
- On resize: update w/h, restart forceCenter, and refit? Refitting would change the camera; user might have zoomed. I'll just update center force and leave the camera; also update initialTransform to new fit so Reset uses sensible framing. Fine.

Write now. Then test in browser: check console errors, screenshots, simulate drag/pan/zoom via browser tools (click, drag). The drag tool: `drag` action with x,y,toX,toY.

Let me first look at the directory.

Full d3 v7 bundle. Now write index.html.

I wrote a sloppy force line: `.force("center", d3.forceX(0).strength(0.045).y(0).strength ? null : null)` — that's garbage. Remove it. Also `d3.forceX(0).strength(0.045).y(0)` would error. Let me clean.

Also a stray CSS `background: linear-gradient(180deg,#2f6db5,#255party);` — invalid, remove.

Also `flash` is used before defined (function declaration → hoisted, fine). `document.getElementById("zoomlvl")` is referenced in setZoomReadout which is called during zoom before legend created? `svg.call(zoom.transform, initial)` happens after setZoomReadout is defined but the legend creation happens later — zoom's "zoom" event fires when applying transform, and setZoomReadout accesses #zoomlvl which doesn't exist yet → error. Need to create legend before applying transform, or guard.

Let me fix these.

Also setZoomReadout uses getElementById("zoomlvl") — guard with null check. And initial transform applied before legend? Now legend created before computeFit/apply. Good, but let me add guard anyway.

Now run in browser.

Graph renders nicely, all 40 nodes visible, clusters ring-shaped, hub dashed links. Console clean.

Zoom shows 100%? computeFit gave k possibly >1 capped at 2.5; but readout says 100%. Let me check: the graph extent ~ width of nodes... Actually the readout is set in the zoom handler; initial transform applied → setZoomReadout called. It says 100% — maybe k ≈ 1.0. Fine.

Now test interactions:
1. Hover node 0 → highlight.
2. Drag a node → links follow, camera unchanged (compare transform before/after).
3. Pan background, wheel zoom, reset view.

The browser tool: click, drag, type, key, scroll. Coordinates in 1200x800 viewport. Node 0 at ~(632,411).

Let me do a drag of node 0 to (800, 300) and screenshot. Also I want to verify camera transform stays. I can't evaluate JS directly... no evaluate tool. I can check the zoom readout text in DOM (in HUD legend) — it changes only on zoom. That's a good proxy for camera invariance during node drag.

Let's do the drag.

The drag worked: node 0 moved to (860,250), links follow (1, 9, 10, 30 stretched toward it), and the hover highlight is active (mouse ended over the node → mouseenter fired, dimming others). Zoom readout still 100% → camera unchanged. 

Two issues:
1. The HUD text got mangled: "Released — the simulation settles. — the graph responds; release to settle." That's because flash sets textContent then a timer resets it; the drag end fired flash and then... Actually the string shows concatenation — that means hudMain.textContent was set while... hmm. `flash` sets textContent = msg, then after 2600ms sets default. The DOM text shows "Released — the simulation settles. — the graph responds; release to settle." Wait, the hud div contains `<b id="hud-main">` and a following text node " — the graph responds; release to settle."! Yes: `<div><b id="hud-main">Drag a node</b> — the graph responds; release to settle.</div>`. So the static suffix text node remains. Fix: remove the suffix from HTML, keep only the <b>.

2. After drag release, the highlight persists (mouse over node) — that's expected behavior since pointer is still on node. Fine. But note the tooltip shows. OK.

Also the node 0 dragged to position and after release the simulation settles — good.

Let me fix the HUD suffix, then test: mouseleave restore, pan, zoom, reset.

Also consider: after drag end, node stays where dropped (fx=null so it may drift back). Fine.

Let me also verify hover restore. Then pan/zoom/reset.

Also, the flash default text after 2600ms is "Drag a node — the graph responds; release to settle." — good as a single string now.

Now reload and test hover restore + pan + zoom + reset.

Fresh layout, deterministic-ish. Now test hover on node 20 (at ~622,507): expect highlight of 19,21,30 and dim others. Then move mouse away → restore.

Note: hovering requires a "click"? The tool has `click` action which moves+clicks; mouseenter should fire. Let me click on node 20 and screenshot.

Actually clicking on a node also triggers drag start/end (d3.drag on mousedown/up) — that's fine, alphaTarget 0.3 restart briefly. Let's use click on node 20.

Hover highlight works: node 20 + neighbours 19, 21, 30, 0 highlighted, connecting links bright, others dimmed. Tooltip shown.

Now test restore on leave: move mouse to empty area. The tool has no "move" action; `scroll` at a position might move the mouse. Let's do a pan drag on background: drag from (200,700) to (400,600) — that pans and also moves pointer away, restoring normal appearance. Then check zoom via wheel (scroll action) and then Reset view.

Note: drag on background pans — but does d3.zoom pan work with the tool's synthetic drag? Let's see.

Pan works (view shifted right/down ~220,-140), and highlight restored to normal after leaving the node. But the tooltip still lingers in the DOM text ("Node 20 ...") — it's opacity 0 presumably; the DOM text retains content but hidden. Fine. Actually is it hidden? The screenshot shows no tooltip → yes, opacity 0.

Now zoom with wheel: scroll action with delta at a position. Then check zoom readout changes. Then Reset view.

Wheel zoom works (230%), labels scale up. Now click Reset view → should return to initial framing (fit, ~100%).

Problem: Reset view did NOT restore the fit framing — it shows zoom 172%/216% and the graph still off-centre (mid-transition? The screenshot was taken right after click, and the transition is 650ms; the readout shows 216% which is between 230% and target... but the target should be ~100%). Hmm, the readout shows 172% in the DOM snapshot and 216% in the screenshot — inconsistent, indicating the screenshot was taken mid-transition (transition still running, interpolating from 230% toward target). Actually 216 > 172 — the DOM text is from the inspect at click time, screenshot taken later... confusing. Either way, it may still be transitioning.

But wait — a bigger issue: `computeFit()` recomputes the fit from the *current* node extents. That's fine. But the target k: initial fit was 100%. Reset should go to ~100%. The screenshot at 216% suggests it's mid-transition. Let me take another screenshot after waiting to confirm final state.

Also concerning: node 20 label appears in DOM but not visible... whatever.

Let me screenshot again to see the settled state.

Reset view restored the exact initial framing (100%, identical layout to first paint). 

Remaining checks:
- Drag a node and confirm links follow while camera stays: verified earlier (zoom stayed 100%, links stretched).
- One thing: the tooltip lingering in DOM after mouse left (hidden, fine).

Small polish: the `svg.on("click")` uses `event.target.tagName === "svg"` — for SVG elements tagName is "svg"? For the root <svg> element, tagName is "svg" (lowercase) in SVG namespace. OK.

Another consideration: labels font-size scaling on zoom — at 230% labels grew, fine.

Potential issue: dragging a node while zoomed — event.x/y in simulation space (d3.pointer with container = parentNode which has the zoom transform) → correct. Let me verify quickly by zooming in and dragging a node to see it track the cursor. Given time budget (used ~7 min?), let me do one quick check: zoom in via scroll, then drag node 10.

Actually a more valuable check: the drag behavior while zoomed. Let's do it: scroll +400 at node 10's location, then drag node.

Hmm, careful: after zoom, node positions on screen change. Let me just do a drag at a location where a node is after zoom. Simpler: I'll trust d3's standard behavior — it's the canonical pattern and coordinates are computed relative to the transformed container. But a quick empirical check is cheap. Let me do: scroll delta -300 at (600,400) → zoom ~1.5x; then screenshot to find a node, then drag it.

That's 3 calls. I have time budget of 15 min; used maybe 8. Let's do it.

The scroll didn't zoom this time (still 100%). Earlier it did (230%). Why? Perhaps the wheel event was dispatched at a point where... hmm, earlier I scrolled at (600,400) delta -600 and it worked. Now delta -300 → no change. Maybe the scroll tool's synthetic wheel needs larger magnitude, or the event was consumed... Odd. Possibly the mouse position for the wheel event landed on the graph but the zoom handler requires the event target to be the svg — it is.

Maybe the wheel delta -300 produced a zoom of 2^(300/500)? d3-zoom wheelDelta: -deltaY * 0.002 * k... deltaY of 300 → factor 2^(0.6)=1.5 → should be 151%. Unless the scroll tool's delta maps to something small per tick.

Let me retry with -600 to confirm zoom still works generally. Then drag a node while zoomed.

Wheel zoom no longer responds at all, though it worked earlier (230%). Something changed after the Reset view transition. Hypothesis: `svg.transition().duration(650).call(zoom.transform, initial)` — d3-zoom's transform applied via transition uses `interpolate` on a transition; if the transition is interrupted or if d3-zoom's internal `__zoom` tween sets a flag... Actually known issue: applying zoom.transform via a transition sets `d3.zoomTransform` and also `noEvent`? d3-zoom's `transform` function, when called on a transition, uses `transition()` with a tween that dispatches events with `event.sourceEvent = null`. It shouldn't break subsequent wheel zoom.

Hmm, but there's a known d3-zoom behavior: wheel zoom is throttled via `wheelDelta` and `touchstarting`... Another known gotcha: after a wheel event with `event.ctrlKey`... no.

Wait — d3-zoom's wheeled handler: 
```js
function wheeled(event, ...args) {
  if (!filter.apply(this, arguments)) return;
  ...
}
```
The default filter: `(!event.ctrlKey || event === wheelDelta) && !event.button` — hmm actually filter is `function defaultFilter(event) { return (!event.ctrlKey || event.type === 'wheel') && !event.button; }`. So `event.button !== 0` blocks. For wheel events, `button` is 0 normally. But if the synthetic wheel event from the browser tool has `button: 1` or something? Earlier it worked though.

Alternatively, the difference: earlier the zoom worked when the pointer was over the svg background. Now I scrolled at (760,367) which is over... node 10 area? No, (760,367) is between nodes; the wheel target would be the svg or a line/circle. If the target is a `circle` (node), wheel still bubbles to svg → zoom handles it. Unless... hmm.

Another possibility: the mouse is hovering over a node, and my mouseenter handler calls `d3.select(this).raise()` — that moves the node element in the DOM, which could disrupt... no, not wheel.

Key suspicion: the tooltip element `#tip` has pointer-events:none. OK.

Wait — maybe the scroll tool requires the pointer to already be positioned; the first scroll worked because a prior action (click at 65,74? no...) Hmm.

Let me consider: maybe the issue is that the wheel event's `deltaMode`/`deltaY` from the tool is in different units, and d3's `defaultWheelDelta` uses `-event.deltaY * (event.deltaMode === 1 ? 0.05 : event.deltaMode ? 1 : 0.002)`. If deltaMode = 1 (lines) → 0.05 * 900 = 45 → k = 2^45 huge → clamped by scaleExtent to 6 → would show 600%. Not the case.

Actually maybe the scroll happened but then... the readout says 100%. Hmm, and the image is identical to before.

Let me check whether the zoom behavior is still attached: after `svg.call(zoom)` we also did `svg.on("click", ...)`. That doesn't remove wheel.zoom.

Oh wait! I see it: `svg.call(zoom).on("dblclick.zoom", null);` — fine. But in `resize()` at the end I call `svg.call(zoom.transform, initial)` — fine.

Hmm, what about the `zoom.on("start")` handler setting `svg.classed("panning", true)` and `.on("end")` false. Fine.

Let me test with a different approach: use `key` or check console. Better: test scroll again immediately with small delta at a clearly-background point like (100,300).

Actually — important clue: the second scroll attempt (delta -300 at 600,400) failed too, and at that time the mouse had been over the HUD/reset button. Maybe the tool's scroll requires the mouse to be over the iframe and it dispatches at the given coords... it worked the first time at exactly (600,400) with -600.

Difference: first successful scroll happened right after a `drag` action. Hmm.

Maybe the issue is that d3-zoom's wheel handler uses a debounce: `wheeled` with `this.__wheeling` — d3-zoom has:
```js
if (event.ctrlKey) ... 
```
Actually d3-zoom v7 code:
```js
function wheeled(event, ...args) {
    if (!filter.apply(this, arguments)) return;
    var g = gesture(this, args).event(event),
        t = this.__zoom,
        k = Math.max(d3_zoom_scaleExtent[0], Math.min(d3_zoom_scaleExtent[1], t.k * Math.pow(2, wheelDelta.apply(this, arguments)))),
        p = pointer(event);
    if (d3_zoom_nocancel) ... 
    if (this.__wheeling) { if (samePoint(points[0], points[1])) { p = points[0]; } else { g.mouse[0][0] = points[0]... }
    ...
    this.__wheeling = d3_timer(... 250ms ... )
```
So consecutive wheel events within 250ms are coalesced. Not blocking.

Hmm — could the transition from Reset view still be "running" and d3-zoom's transform tween sets `this.__zooming`? No.

Let me try to diagnose empirically: do a drag on the background (pan) to see if zoom behavior is still functional at all. If pan works but wheel doesn't, it's wheel-specific. Then I could add a fallback: also handle wheel manually? Better: check if the browser tool's scroll is landing on the element. Let me scroll over a far background area (100, 700).

Still no zoom. So either the tool's scroll stopped working, or something in my page blocks wheel after the first use.

Note: after the first successful wheel zoom, the readout showed 230% — and importantly, the `#hud` div has `pointer-events: none` so that's not it.

Hypothesis: d3-zoom's `wheeled` uses `d3_timer`-based `__wheeling` and calls `event.preventDefault()`. If the tool's scroll is dispatched as a `wheel` event with `passive` listener... d3-zoom registers wheel with `{passive: false}`. Fine.

Another hypothesis: my `zoom.on("zoom")` handler throws an error for subsequent wheel events, breaking the gesture? If an error were thrown, the console would show it. Console shows only the sandbox warning. But errors inside event listeners do show in console usually... The tool's console report may only capture page-load-time messages? It says "console" array — maybe it captures all. Earlier no errors appeared at all.

Wait, maybe the issue is `node.selectAll("text").attr("font-size", ...)` — no error.

Let me test whether pan still works after the reset (drag background). If pan works, the zoom behavior is alive and the wheel event simply isn't reaching the svg (tool issue).

Actually here's a plausible page-side cause: d3-zoom's `wheeled` handler ignores events when `event.ctrlKey` false... no.

Hmm, one more: d3-zoom's default filter is `!event.ctrlKey && !event.button` (v7: `return (!event.ctrlKey || event.type === "wheel") && !event.button;`). Wait no, v7 default filter:
```js
function defaultFilter(event) {
  return (!event.ctrlKey || event.type === 'wheel') && !event.button;
}
```
Hmm, actually it's `!event.ctrlKey && !event.button` in v7? Let me check the minified source. If the tool dispatches wheel with ctrlKey... unlikely.

But there IS a relevant d3-zoom feature: on the *first* wheel event, if `event.ctrlKey` is false it's fine.

Let me look at the tool's behavior differently: maybe the scroll tool scrolls the *page* (document scroll) rather than dispatching a wheel event at coordinates, and the first time it worked because... no, the first time zoom went to 230%, which is clearly a wheel event reaching d3-zoom.

Difference between first success and later failures: the first success came right after `drag` (pan) ended. Later failures came after `click` (Reset view) which used a **transition** on the zoom transform. 

That's the clue! d3-zoom's `transform` on a transition sets `this.__zoom` via `interpolateZoom` and marks `noevent`? Let me look at d3 source for zoom.transform:

```js
function transform(selection, transform, ...) {
  var name = this._ + ".zoom";
  return selection.transition ? (
     selection.tween(name, function() {  // actually:
       ...
     })
  )
}
```
Real code (v7 zoom.js):
```js
transform: function(collection, transform, point, event) {
      var selection = collection.selection ? collection.selection() : collection;
      selection.property("__zoom", defaultTransform);
      if (collection !== selection) {
        schedule(collection, transform, point, event);
      } else {
        selection.interrupt().each(function() {
          gesture(this, arguments)
            .event(event)
            .start()
            .zoom(null, typeof transform === "function" ? transform.apply(this, arguments) : transform)
            .end();
        });
      }
    },
```
`schedule` uses `collection.tween(".zoom", ...)` — and importantly, when a transition is scheduled, d3-zoom's gesture during the tween sets `g.mouse`... Hmm.

Key: `selection.property("__zoom", defaultTransform)` — WAIT. That resets `__zoom` to the identity transform (defaultTransform = () => zoomIdentity) before applying! No — it sets it only if not already set? `selection.property(name, value)` sets it unconditionally... Actually in d3-zoom's transform:

```js
transform(collection, transform, point, event) {
  var selection = collection.selection ? collection.selection() : collection;
  selection.property("__zoom", defaultTransform);
  if (collection !== selection) {
    schedule(collection, transform, point, event);
  }
```
Hmm, `defaultTransform` is a function returning `this.__zoom == null ? identity : this.__zoom`:
```js
function defaultTransform() {
  return this.__zoom || identity;
}
```
Yes! `defaultTransform` returns existing `__zoom` or identity. So it's a no-op-ish. OK.

So what breaks wheel? Let's check `gesture`/`wheeled` code for a state that could persist. In v7:

```js
function wheeled(event, ...args) {
    if (!filter.apply(this, args)) return;
    var g = gesture(this, args).event(event),
        t = this.__zoom,
        k = Math.max(...),
        p = pointer(event);
    if (wheening) {
      if (Date.now() - wheeltime >= 150) g.wheelDelta = 0; // hmm
      ...
    }
```
Actual v7 code:
```js
  function wheeled(event, ...args) {
    if (!filter.apply(this, arguments)) return;
    var g = gesture(this, args).event(event),
        t = this.__zoom,
        k = Math.max(scaleExtent[0], Math.min(scaleExtent[1], t.k * Math.pow(2, wheelDelta.apply(this, arguments)))),
        p = pointer(event);

    // If the mouse is in the same location as before, reuse it.
    // If there are recent wheel events, reset the timeout.
    // If there are not recent wheel events, acquire a new gesture.
    if (wheening) {
      if (!equal(p, g.mouse[0][0])) { ... }
    } else {
      g.mouse[0] = [p, t.invert(p)];
      interrupt(this);   // <-- interrupts transitions
      g.start("wheel", "mousemove");
    }
    ...
```
Hmm, `wheening` is a module-level variable set true, with `clearTimeout(wheeltimeout)`, `wheeltimer = setTimeout(() => { g.end("wheel","mousemove"); delete this.__wheeling; wheening = false; }, 150)`.

Wait, in v7 the code is:

```js
let wheelevent, wheeltimer, wheendelta; // ...
function wheeled(event, ...args) {
    ...
    if (wheening) {...} else {...}
```
I recall there's a subtlety: `if (wheening) ... else { ... wheening = true; }` and the timer sets `wheening = false`. If the timer callback throws before resetting `wheening`, subsequent wheel events take the "wheening" branch with stale state → possibly no visible zoom. But what would throw?

My `zoom.on("zoom")` handler runs during g.zoom. If it throws, `wheening` never resets → subsequent wheel events do nothing (or error). That matches the symptom: first wheel worked, then nothing.

What could throw in my handler? `setZoomReadout(event.transform)` → `document.getElementById("zoomlvl").textContent = ...`. #zoomlvl exists (legend created before). Hmm.

But wait: the first successful wheel zoom (230%) happened BEFORE I clicked Reset. Then Reset used a transition. Then wheel stopped working. So the breakage correlates with the transition, not with my handler.

`interrupt(this)` in the wheel branch: if a zoom transition is scheduled via `schedule()` which uses `transition.tween(".zoom", ...)`, and then a wheel gesture interrupts the element... `interrupt(node)` stops transitions on it, but the scheduled tween's `.cancel`? Hmm.

Alternatively, d3-zoom's `schedule` sets `collection.on("interrupt", ...)`? There's a known issue: "zoom transitions block subsequent gestures"? Not that I recall.

Let me look at the actual minified code in the file to reason precisely about `wheeled`.

Actually, more efficient: empirically test. Let me reload the page and try wheel twice in a row (two scrolls without any reset click). If the second also fails, the bug is in my code's wheel handling path (wheening state), not the transition.

Let me do that: reload, scroll -600 at (600,400), then scroll -600 again at (600,400), then screenshot.

Same initial layout (deterministic — good, pre-warm makes it stable). Now scroll twice.

Now the very first wheel after a fresh reload does NOT zoom either. So the earlier 230% was a fluke? Interesting — earlier the successful wheel came right after a `drag` action (which moved the mouse to 420,560... no wait, the successful wheel at (600,400) came after the click at (622,507) hover test... hmm, actually the order was: reload → click node 20 → drag background → scroll -600 at (600,400) → ZOOMED to 230%.

So the wheel worked once. Now it doesn't. What differs? Possibly the tool's scroll implementation dispatches a wheel event only if the mouse is "over" the page and it needs a preceding mouse move; maybe it uses `Input.dispatchMouseEvent` with type mouseWheel and the coordinates. It should work regardless.

Alternatively: maybe the scroll DID work but the readout... no, image unchanged.

Hmm, maybe the page needs focus/hover state. Let me try: click on background first (which triggers a mouse move + click), then scroll.

Also possible: my `svg.on("click", ...)` handler? No.

Let me test the hypothesis that it's the tool needing a prior mouse move: do a `key` or `click` on background then scroll.

Actually — earlier sequence: `drag` (background pan) → then `scroll` worked. The drag ends with the mouse at the target position. So maybe the tool's scroll uses the *current* mouse position and dispatches wheel there; if the mouse has never been moved, coordinates might be (0,0) → outside svg? No, (0,0) is inside the svg? The svg starts below the header, so (0,0) is the header → wheel over header → no zoom. That would explain: my scroll at (600,400) with no prior mouse move → dispatched at stale position (0,0)?? But after the reload, the previous mouse position was (120,700) from the last scroll... which was inside the svg. Hmm, but that failed too.

Let me try: click at empty background (e.g. 100,300) then scroll at (600,400).

Good: clicking background cleared highlight (nothing was highlighted). Now scroll at (600,400).

Wheel zoom works (230%). The earlier failures were a harness quirk: the scroll tool needs a prior mouse-position-establishing action (a click/drag) — i.e., the wheel was dispatched at a stale/off-target position. Notably the two failing scrolls happened right after a reload (mouse position reset). So it's a tool artifact, not an app bug.

Now let's verify dragging a node while zoomed (coordinate space correctness), then Reset view.

Node 0 is at right edge ~(1195, 555) partially off. Let's drag node 1 at (1058, 539) to (700, 400). Then screenshot: links should follow, camera unchanged (230%).

Node 1 landed exactly under the cursor at (700,380) while zoomed at 230% — drag coordinates are correctly in simulation space. Links to 0 and 2 follow. Camera unchanged (still 230%). Hover highlight active (1 + neighbours 0,2 bright, rest dimmed).

Now click Reset view and confirm framing returns to 100% fit. Note: computeFit uses current node extents (which changed slightly due to drag) — the framing will be close to initial. Requirement: "restore the initial camera framing". Better to freeze the initial transform computed at load time rather than recompute. But recomputing adapts if the graph drifted... The spec says "restore the initial camera framing" — safest: store the initial transform once at load and reuse it; but if the user drags the graph far, the original framing might not fit. Hmm. Requirement is explicit: initial framing. I'll store `initial` at load and NOT recompute on Reset (only recompute on resize). Actually a compromise: keep the load-time transform as the reset target. That literally satisfies "restore the initial camera framing without replacing the graph data."

Let me change resetView to use the stored initial (computed at load / last resize) without recomputing.

Then verify reset works.

But `resize()` recomputes `initial` on every window resize — that's fine (viewport changed). However, resize also gets called once at the end of the script, which recomputes initial = computeFit() (same value). Good.

Wait, there's a subtlety: `resize()` is called at the end and sets initial from current extents — same as before since positions unchanged. Good.

Now reload and test: click background (to set mouse pos), scroll zoom, then reset.

Now: pan the background (drag), then scroll zoom, then Reset view — and verify it returns to this exact framing.

Do drag from (200,200) to (500,450) → pan. Then scroll needs a prior mouse move (the drag provides it). Then click Reset view at (65,74) — but clicking the button moves the mouse; then screenshot after transition.

Let's do drag first.

Pan works (moved +320,+270). Now zoom out (scroll +400) then Reset view.

Zoom out works (58%). Now click Reset view and verify it returns to the 100% initial framing.

Mid-transition (60%). Screenshot taken during the 650ms transition. Let me take another screenshot to see the settled state.

Reset view restored the exact initial framing (pixel-identical to first load, 100%). All required behaviors verified.

Final tidy: remove the unused `key` helper? It's harmless. Let me quickly verify no leftover issues: `key` unused — fine, but let me remove for cleanliness. Also verify the file has no syntax errors (browser ran fine).

One more small thing: hovering a node while dragging — fine.

Let me do a final syntax check via node (parse the script? it uses DOM). Just do a quick grep for the unused function and remove it, then confirm the page still loads.

Time used ~13 min. I'll do the tiny cleanup and one final reload check.

Unused; I'll leave it or remove. Removing is trivial but risks nothing. Let me remove it and reload once.

Actually each edit + reload costs time. The unused helper is harmless. But cleanliness matters little. I'll remove it in one edit and do a final reload to confirm no errors (cheap).

python3 not available. Use node instead.

Also remove the unused `linked`? No, it's used. And the unused `svg.on("click")`? used.

Final reload to confirm clean console and render.

All good. Final state: index.html complete, self-contained, only local d3.min.js. Console clean (only the harness's sandbox iframe warning, unrelated to the app).

Report concisely.