The editor's grown frame stays in the editor

Audit dev@2c947f4, DEV-2C947-02 (P2). Move the only room from 0.1..0.9 to
5.1..5.9 inside the Plan editor and go back to View: the frame stayed 5880
units wide instead of the room's 880, and only a manual `_frame = null` put it
right. Anything that moves, deletes or heavily resizes geometry in an editor
left View looking at ground the plan no longer occupies — until some unrelated
model/layout/device change happened to invalidate the memo.

The growth itself is deliberate and stays (docs/CANVAS.md §4.3): inside an
editor the frame bounds pan and defines what zoom 1 means, and one that shrank
the instant a room was deleted would move the ground under a live gesture. The
bug was that the growth was invisible to the memo — `_frame`'s key carried the
space, the model, the layout, the devices and the show-far flag, but not the
mode, so the accumulated union was handed straight back in View.

`grow` (`_mode !== 'view'`) is now part of the key, and the union is only ever
taken against a frame the same editor session produced. Leaving an editor
recomputes from the content; entering one starts from the current geometry
instead of resurrecting the union of a previous session.

smoke_canvas_frame.mjs grows the auditor's scenario: the frame before, the
union inside the editor (asserted, so the growth cannot be "fixed" by deleting
it), the frame after exit — 5060..5940 — and re-entry. Two checks are red on
the parent commit.

demo/smoke_canvas_frame.mjs

@@ -4,6 +4,10 @@
 // frame — hiding a marker that had wandered into the yard left the visible
 // house a dot in the corner (the full card AND the static
 // houseplan-space-card, which drew `devs` but framed `spaceDevs`).
+//
+// DEV-2C947-02: inside an editor the frame only grows (a frame that shrank
+// mid-drag would move the ground under the pointer); that union was memoised
+// without the mode, so it survived the way back into View.
 import { launch, checkAll, finish } from './serve.mjs';
 
 const { page, browser } = await launch({ width: 900, height: 820 }, 1);
@@ -114,5 +118,51 @@ Object.assign(out, await page.evaluate(async () => {
   return o;
 }));
 
+// ------------------------------------------------------- 02: editor -> view
+const oneRoomAt = (x0) => ({
+  spaces: [{
+    id: 'e1', title: 'Editor', view_box: [0, 0, 1, 1], plan_url: null, plan_aspect: null,
+    rooms: [{ id: 'r1', name: 'Room', area: 'zx_room',
+      poly: [[x0, 0.1], [x0 + 0.8, 0.1], [x0 + 0.8, 0.9], [x0, 0.9]] }],
+  }],
+  markers: [], settings: { filter_seeded: true },
+});
+
+await load(oneRoomAt(0.1), {}, 'e1');
+await raf();
+Object.assign(out, await page.evaluate(async () => {
+  const c = window.__card;
+  const o = {};
+  const round = () => c._baseVb().map((n) => Math.round(n));
+  o.viewFrameBefore = JSON.stringify(round()) === JSON.stringify([60, 60, 880, 880]);
+  // move the only room 5 canvases to the right, inside the Plan editor
+  c._setMode('plan');
+  await c.updateComplete;
+  const cfg = JSON.parse(JSON.stringify(c._serverCfg));
+  cfg.spaces[0].rooms[0].poly = [[5.1, 0.1], [5.9, 0.1], [5.9, 0.9], [5.1, 0.9]];
+  c._serverCfg = cfg;
+  c._modelCache = null;
+  c._cfgEpoch++;
+  c.requestUpdate();
+  await c.updateComplete;
+  const inEditor = round();
+  // inside the editor the frame is the UNION — that is deliberate: it bounds
+  // pan and defines zoom 1, and it must not shrink under a live gesture
+  o.editorFrameOnlyGrows = inEditor[2] > 5000;
+  c._setMode('view');
+  await c.updateComplete;
+  const back = round();
+  o.viewFrameFollowsTheRoomAgain = JSON.stringify(back) === JSON.stringify([5060, 60, 880, 880]);
+  if (!o.viewFrameFollowsTheRoomAgain) console.log('frame after exit', back, 'editor', inEditor);
+  // and back into an editor it starts from the CURRENT geometry, not the old union
+  c._setMode('plan');
+  await c.updateComplete;
+  o.reenteringTheEditorDoesNotResurrectTheUnion =
+    JSON.stringify(round()) === JSON.stringify([5060, 60, 880, 880]);
+  c._setMode('view');
+  await c.updateComplete;
+  return o;
+}));
+
 checkAll(out);
 await finish(browser, out);

docs/CANVAS.md

@@ -139,6 +139,19 @@ When `outliers > 0` the card shows an unobtrusive inline hint (no
 modal) — "there are objects far from the plan" with a **Show** action
 that fits `all`.
 
+### §4.3 The frame in an editor
+
+Inside an editor the frame only ever **grows** (`unionRect` with the previous
+one): it bounds pan and defines what zoom 1 means, and a frame that shrank the
+instant a room was deleted would move the ground under a live gesture.
+
+That union belongs to the editor session and to nothing else. The memo key
+carries the growth flag, so leaving for View recomputes the frame from the
+content instead of inheriting the union — otherwise a room dragged five
+canvases away in the Plan editor kept View framing the empty ground it had
+left behind, until some unrelated model change happened to invalidate the memo
+(audit DEV-2C947-02).
+
 ### §4.2 Degenerate frames
 
 An SVG `viewBox` with a zero axis paints nothing, so a frame still has

docs/TESTING.md

@@ -998,6 +998,11 @@ require hands on real hardware — they remain for the human pass.
       frame, on the full card and on `houseplan-space-card`. Untick it and the
       frame takes it in again; room LQI counted it the whole time
       [auto: smoke_canvas_frame]
+- [ ] **The editor frame does not follow you out** (audit DEV-2C947-02): move
+      the only room five canvases away in the Plan editor (the frame grows
+      there, deliberately), close the editor — View frames the room where it
+      is NOW, not the union with where it was; re-entering the editor starts
+      from the current geometry [auto: smoke_canvas_frame]
 - [ ] **A far stray does not break the view** (§4.1): a marker dragged an
       order of magnitude away leaves the opening view alone and raises the
       inline chip «Объектов далеко от плана: N» with «Показать». No modal.

src/houseplan-card.ts

@@ -1843,7 +1843,7 @@ class HouseplanCard extends LitElement {
    */
   private _frame:
     | { id: string; model: SpaceModel; layout: unknown; devs: unknown; far: boolean;
-        rect: Rect; all: Rect; outliers: number }
+        grow: boolean; rect: Rect; all: Rect; outliers: number }
     | null = null;
   /** The outlier hint's «Показать» is on: the frame takes in the far strays
    *  too, so zoom, pan and the fit button all agree about what "everything"
@@ -1857,21 +1857,28 @@ class HouseplanCard extends LitElement {
     // content changes, so this catches a marker drag and a server push alike —
     // an epoch would have to be bumped at every one of those call sites.
     const f = this._frame;
+    // `grow` is part of the KEY, not just of the computation (DEV-2C947-02):
+    // the union an editor accumulated is an editor's frame, and leaving for
+    // View has to recompute rather than inherit it — otherwise a room moved
+    // far away in the Plan editor kept View framing the empty ground it left
+    // behind, until some unrelated model change happened to invalidate memo.
+    const grow = this._mode !== 'view';
     if (f && f.id === m.id && f.model === m && f.layout === this._layout
-        && f.devs === this._devices && f.far === this._showFar) return f;
+        && f.devs === this._devices && f.far === this._showFar && f.grow === grow) return f;
     const cf = contentFrame(this._contentItems(m));
     let all = cf.all || spaceFrame(m);
     let rect = this._showFar ? all : (cf.core || spaceFrame(m));
-    if (f && f.id === m.id && this._mode !== 'view') {
+    if (f && f.id === m.id && grow && f.grow) {
       // Inside an editor the frame only GROWS: it bounds pan and defines what
       // zoom 1 means, and a frame that shrank the instant a room was deleted
-      // would move the ground under the pointer mid-gesture.
+      // would move the ground under the pointer mid-gesture. Only ever unions
+      // with a frame the SAME editor session produced (f.grow).
       rect = unionRect(f.rect, rect);
       all = unionRect(f.all, all);
     }
     this._frame = {
       id: m.id, model: m, layout: this._layout, devs: this._devices,
-      far: this._showFar, rect, all, outliers: cf.outliers,
+      far: this._showFar, grow, rect, all, outliers: cf.outliers,
     };
     return this._frame;
   }