fix(dashboard): t-paliad-228 — collision-aware widget placement (m/paliad#70)

After m/paliad#69's edit-mode overhaul, widgets visually overlapped on
mixed-size rows: a 12-col + 6-col swap, an auto-flow widget landing on
an explicit blocker, or a resize-grow into a sibling all produced
layouts that ignored colspan footprints when computing occupancy.

Extracts placement math from dashboard.ts into a pure ./dashboard-grid
module and adds an occupancy bitmap. Every visible widget is placed
once; explicit-position collisions are resolved by searching downward
from the requested row for the first w×h block that fits, preferring
the requested column. Resize-grow + drag-drop swap now reliably
produce no-overlap layouts because the placer cleans up after them.

x+w > GRID_COLUMNS is clamped in the placer instead of rendered as an
overflow — matches the validator's hard rule on the wire.

Adds 14 dashboard-grid.test.ts regressions covering the mixed-width
swap, resize-grow shifting siblings, multi-row widgets, and the
overflow clamp. Pure tests — no DOM.

frontend/src/client/dashboard-grid.test.ts

@@ -0,0 +1,226 @@
+import { describe, expect, test } from "bun:test";
+import {
+  GRID_COLUMNS,
+  clampH,
+  clampW,
+  placeWidgets,
+  type WidgetPlacementInput,
+} from "./dashboard-grid";
+
+// Regression suite for m/paliad#70 (t-paliad-228): the post-#69 edit
+// mode produced overlapping widgets when a 2-col widget sat next to a
+// 1-col widget on the same row, when a drag swapped widgets of
+// different widths, and when a resize grew a widget into a sibling. The
+// fix moved the placement math into ./dashboard-grid + made it
+// collision-aware. These tests pin the no-overlap invariant.
+
+function spec(
+  key: string,
+  x: number | undefined,
+  y: number | undefined,
+  w: number,
+  h = 1,
+  visible = true,
+): WidgetPlacementInput {
+  return { key, visible, x, y, w, h };
+}
+
+// hasOverlap returns true if any placed pair shares a cell. O(n²) is
+// fine — layouts cap at 32 widgets and the tests stay tiny.
+function hasOverlap(rects: Map<string, { x: number; y: number; w: number; h: number }>): string | null {
+  const list = Array.from(rects.entries());
+  for (let i = 0; i < list.length; i++) {
+    const [ka, a] = list[i];
+    for (let j = i + 1; j < list.length; j++) {
+      const [kb, b] = list[j];
+      const xOverlap = a.x < b.x + b.w && b.x < a.x + a.w;
+      const yOverlap = a.y < b.y + b.h && b.y < a.y + a.h;
+      if (xOverlap && yOverlap) return `${ka} ↔ ${kb} at (${a.x},${a.y},${a.w}x${a.h}) vs (${b.x},${b.y},${b.w}x${b.h})`;
+    }
+  }
+  return null;
+}
+
+describe("placeWidgets — basic auto-flow", () => {
+  test("places two 6-wide widgets side by side on row 0", () => {
+    const out = placeWidgets([
+      spec("a", undefined, undefined, 6),
+      spec("b", undefined, undefined, 6),
+    ]);
+    expect(out.get("a")).toEqual({ x: 0, y: 0, w: 6, h: 1 });
+    expect(out.get("b")).toEqual({ x: 6, y: 0, w: 6, h: 1 });
+    expect(hasOverlap(out)).toBeNull();
+  });
+
+  test("wraps when row doesn't fit", () => {
+    const out = placeWidgets([
+      spec("a", undefined, undefined, 8),
+      spec("b", undefined, undefined, 8),
+    ]);
+    expect(out.get("a")!.y).toBe(0);
+    expect(out.get("b")!.y).toBeGreaterThan(0);
+    expect(hasOverlap(out)).toBeNull();
+  });
+
+  test("hidden widgets are skipped and reserve no cells", () => {
+    const out = placeWidgets([
+      spec("hidden", 0, 0, 12, 1, false),
+      spec("visible", undefined, undefined, 6),
+    ]);
+    expect(out.has("hidden")).toBe(false);
+    expect(out.get("visible")).toEqual({ x: 0, y: 0, w: 6, h: 1 });
+  });
+});
+
+describe("placeWidgets — explicit positions, no collision", () => {
+  test("trusts non-colliding explicit positions exactly", () => {
+    const out = placeWidgets([
+      spec("a", 0, 0, 6),
+      spec("b", 6, 0, 6),
+      spec("c", 0, 1, 12),
+    ]);
+    expect(out.get("a")).toEqual({ x: 0, y: 0, w: 6, h: 1 });
+    expect(out.get("b")).toEqual({ x: 6, y: 0, w: 6, h: 1 });
+    expect(out.get("c")).toEqual({ x: 0, y: 1, w: 12, h: 1 });
+    expect(hasOverlap(out)).toBeNull();
+  });
+});
+
+describe("placeWidgets — mixed-width collision (m/paliad#70 regression)", () => {
+  test("1-col + 2-col on same row do not overlap when both explicit", () => {
+    // Half-width left + half-width right is the canonical 'two widgets per
+    // row' layout; pre-fix this was fine but the next regression below
+    // exercises the actual bug.
+    const out = placeWidgets([
+      spec("left", 0, 0, 6),
+      spec("right", 6, 0, 6),
+    ]);
+    expect(hasOverlap(out)).toBeNull();
+  });
+
+  test("4-col + 8-col both claiming (0,0) end up non-overlapping", () => {
+    // Simulates a post-#69 layout where a 4-wide widget sits at (0, 0)
+    // and an 8-wide widget got accidentally placed at (0, 0) too (e.g.
+    // a buggy reset path or a stale spec from before #70). Placer must
+    // honour the first one's position and fit the second somewhere
+    // free — landing it on the same row at x=4 is acceptable (better
+    // density) as long as nothing overlaps.
+    const out = placeWidgets([
+      spec("first", 0, 0, 4),
+      spec("colliding", 0, 0, 8),
+    ]);
+    expect(out.get("first")).toEqual({ x: 0, y: 0, w: 4, h: 1 });
+    expect(out.get("colliding")!.w).toBe(8);
+    expect(hasOverlap(out)).toBeNull();
+  });
+
+  test("drag-drop swap of 12-wide onto 6-wide does not overlap", () => {
+    // Setup before swap:
+    //   A at (0, 0, w=12) — full width row 0
+    //   B at (0, 1, w=6)  — half row 1 left
+    //   C at (6, 1, w=6)  — half row 1 right
+    // User drags A onto B. reorderViaDnd swaps (x, y):
+    //   A.x=0, A.y=1
+    //   B.x=0, B.y=0
+    // Result must not overlap C.
+    const out = placeWidgets([
+      spec("a", 0, 1, 12),
+      spec("b", 0, 0, 6),
+      spec("c", 6, 1, 6),
+    ]);
+    expect(hasOverlap(out)).toBeNull();
+  });
+
+  test("auto-flow widget steps past explicit blocker on same row", () => {
+    // Explicit widget at (6, 0, w=6); auto-flow widget would pack into
+    // (0, 0, w=6) which is fine — but the next auto-flow widget at w=6
+    // would want (6, 0) which is taken. Placer must wrap it.
+    const out = placeWidgets([
+      spec("flow-a", undefined, undefined, 6),
+      spec("anchored", 6, 0, 6),
+      spec("flow-b", undefined, undefined, 6),
+    ]);
+    expect(out.get("flow-a")).toEqual({ x: 0, y: 0, w: 6, h: 1 });
+    expect(out.get("anchored")).toEqual({ x: 6, y: 0, w: 6, h: 1 });
+    expect(out.get("flow-b")!.y).toBeGreaterThan(0);
+    expect(hasOverlap(out)).toBeNull();
+  });
+});
+
+describe("placeWidgets — resize-grow shifts siblings", () => {
+  test("growing a 6-wide to 12-wide bumps the sibling on the same row", () => {
+    // Pre-resize state:
+    //   A at (0, 0, w=6)
+    //   B at (6, 0, w=6)
+    // User resizes A to w=12. resizeWidget() updates A.w but leaves B
+    // at (6, 0). Placer must shift B down.
+    const out = placeWidgets([
+      spec("a", 0, 0, 12),
+      spec("b", 6, 0, 6),
+    ]);
+    expect(out.get("a")).toEqual({ x: 0, y: 0, w: 12, h: 1 });
+    expect(out.get("b")!.y).toBeGreaterThan(0);
+    expect(hasOverlap(out)).toBeNull();
+  });
+
+  test("growing widget pushes only the first colliding sibling", () => {
+    // A grows to 12-wide; B and C on row 0 are both colliding. Both must
+    // move; their relative order on row 0 is preserved (B at x=0, C at
+    // x=6) on row 1.
+    const out = placeWidgets([
+      spec("a", 0, 0, 12),
+      spec("b", 0, 0, 4),
+      spec("c", 4, 0, 4),
+    ]);
+    expect(hasOverlap(out)).toBeNull();
+    expect(out.get("a")!.y).toBe(0);
+    expect(out.get("b")!.y).toBeGreaterThan(0);
+    expect(out.get("c")!.y).toBeGreaterThan(0);
+  });
+});
+
+describe("placeWidgets — explicit position overflow clamp", () => {
+  test("x+w > GRID_COLUMNS is clamped not rejected", () => {
+    // A 12-wide widget with x=6 would extend past col 11. Placer must
+    // clamp x to 0 (or wherever fits) so the widget renders inside the
+    // grid.
+    const out = placeWidgets([
+      spec("wide", 6, 0, 12),
+    ]);
+    const r = out.get("wide")!;
+    expect(r.x + r.w).toBeLessThanOrEqual(GRID_COLUMNS);
+    expect(r.w).toBe(12);
+  });
+});
+
+describe("placeWidgets — vertical (multi-row) widgets", () => {
+  test("a 2-row-tall widget reserves both rows", () => {
+    const out = placeWidgets([
+      spec("tall", 0, 0, 6, 2),
+      spec("collides-on-row-1", 0, 1, 6, 1),
+    ]);
+    expect(out.get("tall")).toEqual({ x: 0, y: 0, w: 6, h: 2 });
+    // The colliding widget must move because tall covers cols 0..5
+    // on both row 0 and row 1. The placer may shift it to the right
+    // half of row 1 (cols 6..11) or to a later row — either is fine
+    // as long as nothing overlaps.
+    const other = out.get("collides-on-row-1")!;
+    expect(other.x >= 6 || other.y >= 2).toBe(true);
+    expect(hasOverlap(out)).toBeNull();
+  });
+});
+
+describe("clamp helpers", () => {
+  test("clampW respects min/max bounds", () => {
+    expect(clampW(2, { min_w: 4, max_w: 12 })).toBe(4);
+    expect(clampW(20, { min_w: 4, max_w: 12 })).toBe(12);
+    expect(clampW(0, { default_w: 6 })).toBe(6);
+    expect(clampW(NaN, { default_w: 8 })).toBe(8);
+  });
+
+  test("clampH respects min/max bounds and MAX_ROW_SPAN", () => {
+    expect(clampH(0, { default_h: 2 })).toBe(2);
+    expect(clampH(99, undefined)).toBe(5); // MAX_ROW_SPAN
+    expect(clampH(1, { min_h: 3 })).toBe(3);
+  });
+});

frontend/src/client/dashboard-grid.ts

@@ -0,0 +1,216 @@
+// dashboard-grid — pure layout math for the dashboard widget grid.
+//
+// Lives outside dashboard.ts so the placement logic is importable from
+// tests without dragging in the DOM-side rendering code. The grid is a
+// 12-column CSS Grid matching internal/services/dashboard_layout_spec.go;
+// rows grow vertically as widgets are placed.
+//
+// The core invariant is no-overlap: after placeWidgets() returns, every
+// pair of widgets occupies disjoint cells. Pre-overhaul callers wrote
+// computePlacements() to trust explicit (x, y) without checking — that
+// produced visual overlap whenever a drag or resize landed a widget on
+// cells another widget already covered (m/paliad#70). The collision-
+// aware placer below shifts colliding widgets to the next free row so
+// the rendered grid never overlaps regardless of the input spec.
+
+export const GRID_COLUMNS = 12;
+export const MAX_ROW_SPAN = 5;
+
+// Hard cap on the row-scan depth in findFreeSlot. The widget cap on a
+// single layout is 32 (LayoutWidgetCap on the Go side); each row holds
+// at least one widget, so 256 rows is an order-of-magnitude buffer
+// against runaway loops on pathological inputs.
+const MAX_SCAN_ROWS = 256;
+
+export interface PlacedRect {
+  x: number;
+  y: number;
+  w: number;
+  h: number;
+}
+
+// WidgetSizeBound captures the per-widget min/max/default clamps the
+// catalog publishes. Optional fields keep callers from having to
+// synthesize zeroes when the catalog entry is missing.
+export interface WidgetSizeBound {
+  default_w?: number;
+  default_h?: number;
+  min_w?: number;
+  max_w?: number;
+  min_h?: number;
+  max_h?: number;
+}
+
+// WidgetPlacementInput is the per-widget data the placer consumes. The
+// catalog bound is optional — when missing, defaults fall back to a
+// full-width 1-row widget.
+export interface WidgetPlacementInput {
+  key: string;
+  visible: boolean;
+  x?: number;
+  y?: number;
+  w?: number;
+  h?: number;
+  bound?: WidgetSizeBound;
+}
+
+export function clampW(w: number, bound: WidgetSizeBound | undefined): number {
+  let v = Math.round(w);
+  if (!Number.isFinite(v) || v <= 0) v = bound?.default_w ?? GRID_COLUMNS;
+  v = Math.max(1, Math.min(GRID_COLUMNS, v));
+  if (bound?.min_w && v < bound.min_w) v = bound.min_w;
+  if (bound?.max_w && v > bound.max_w) v = bound.max_w;
+  return v;
+}
+
+export function clampH(h: number, bound: WidgetSizeBound | undefined): number {
+  let v = Math.round(h);
+  if (!Number.isFinite(v) || v <= 0) v = bound?.default_h ?? 1;
+  v = Math.max(1, Math.min(MAX_ROW_SPAN, v));
+  if (bound?.min_h && v < bound.min_h) v = bound.min_h;
+  if (bound?.max_h && v > bound.max_h) v = bound.max_h;
+  return v;
+}
+
+// Occupancy bitmap: one row → Uint8Array of GRID_COLUMNS bits. Rows are
+// created lazily so the map only stores rows the layout actually
+// reaches. Cell value 1 = occupied.
+class Occupancy {
+  private rows = new Map<number, Uint8Array>();
+
+  row(y: number): Uint8Array {
+    let r = this.rows.get(y);
+    if (!r) {
+      r = new Uint8Array(GRID_COLUMNS);
+      this.rows.set(y, r);
+    }
+    return r;
+  }
+
+  free(x: number, y: number, w: number, h: number): boolean {
+    if (x < 0 || y < 0 || x + w > GRID_COLUMNS) return false;
+    for (let yy = y; yy < y + h; yy++) {
+      const row = this.row(yy);
+      for (let xx = x; xx < x + w; xx++) {
+        if (row[xx]) return false;
+      }
+    }
+    return true;
+  }
+
+  mark(x: number, y: number, w: number, h: number): void {
+    for (let yy = y; yy < y + h; yy++) {
+      const row = this.row(yy);
+      for (let xx = x; xx < x + w; xx++) row[xx] = 1;
+    }
+  }
+}
+
+// findFreeSlot scans for the first (x, y) where a w×h block fits without
+// collision, starting at row startY. At each row preferX is tried first
+// — that keeps a widget close to its requested column when only the row
+// is blocked. Falls back to left-to-right scan within the row, then to
+// the next row. Caller guarantees w ≤ GRID_COLUMNS.
+function findFreeSlot(
+  occ: Occupancy,
+  startY: number,
+  w: number,
+  h: number,
+  preferX: number,
+): { x: number; y: number } {
+  for (let y = startY; y < startY + MAX_SCAN_ROWS; y++) {
+    if (preferX >= 0 && preferX + w <= GRID_COLUMNS && occ.free(preferX, y, w, h)) {
+      return { x: preferX, y };
+    }
+    for (let x = 0; x + w <= GRID_COLUMNS; x++) {
+      if (x === preferX) continue;
+      if (occ.free(x, y, w, h)) return { x, y };
+    }
+  }
+  // Pathological fallback — caller's widget cap (32) makes this
+  // unreachable in practice. Snap to the bottom-left so the widget at
+  // least renders somewhere visible instead of vanishing.
+  return { x: 0, y: startY + MAX_SCAN_ROWS };
+}
+
+// placeWidgets assigns no-overlap grid coordinates to every visible
+// widget. Hidden widgets are skipped and contribute no placement.
+//
+// Algorithm: iterate widgets in input order. For each visible widget:
+//   1. Clamp w/h against catalog bounds.
+//   2. If the spec carries explicit x and y, try that slot. On a
+//      collision, search downward starting at the requested y for the
+//      first free w×h block (preferring the requested x).
+//   3. If only x is explicit, search from y=0 at that x.
+//   4. Otherwise auto-flow: pack left-to-right under a running cursor;
+//      when the row doesn't fit or is blocked by an explicitly-placed
+//      widget, wrap to the next free row.
+//
+// The mixed-spec case (some widgets explicit, others auto-flow) is the
+// real-world layout — placing the explicit widgets first would change
+// the visual order, so we keep input order and let auto-flow widgets
+// step around any explicit blockers via the same collision search.
+export function placeWidgets(
+  widgets: WidgetPlacementInput[],
+): Map<string, PlacedRect> {
+  const out = new Map<string, PlacedRect>();
+  const occ = new Occupancy();
+
+  // Auto-flow cursor — advances as we place flowed widgets. cursorY
+  // tracks the row currently being filled; rowMaxH is the tallest
+  // widget in that row so wrapping advances past it (not just past the
+  // new widget's height — that would let taller previous neighbours
+  // overlap into the wrap row).
+  let cursorX = 0;
+  let cursorY = 0;
+  let rowMaxH = 0;
+
+  for (const w of widgets) {
+    if (!w.visible) continue;
+    const dw = clampW(w.w ?? w.bound?.default_w ?? GRID_COLUMNS, w.bound);
+    const dh = clampH(w.h ?? w.bound?.default_h ?? 1, w.bound);
+
+    const hasX = typeof w.x === "number";
+    const hasY = typeof w.y === "number";
+    let placed: { x: number; y: number };
+
+    if (hasX && hasY) {
+      // Clamp x so the widget never overflows the right edge — drag/
+      // resize gestures can produce x+w > GRID_COLUMNS otherwise.
+      const prefX = Math.max(0, Math.min(GRID_COLUMNS - dw, w.x as number));
+      const prefY = Math.max(0, w.y as number);
+      if (occ.free(prefX, prefY, dw, dh)) {
+        placed = { x: prefX, y: prefY };
+      } else {
+        placed = findFreeSlot(occ, prefY, dw, dh, prefX);
+      }
+    } else if (hasX) {
+      const prefX = Math.max(0, Math.min(GRID_COLUMNS - dw, w.x as number));
+      placed = findFreeSlot(occ, 0, dw, dh, prefX);
+    } else {
+      // Auto-flow. Wrap the cursor when the widget wouldn't fit in the
+      // remaining columns of the current row, then ask findFreeSlot to
+      // honour the cursor's preferred (x, y) — that lets it step past
+      // any explicit widget that already claimed cells under the
+      // cursor.
+      if (cursorX + dw > GRID_COLUMNS) {
+        cursorY += rowMaxH || 1;
+        cursorX = 0;
+        rowMaxH = 0;
+      }
+      placed = findFreeSlot(occ, cursorY, dw, dh, cursorX);
+      if (placed.y > cursorY) {
+        // Wrap was forced by a collision deeper than the current row.
+        cursorY = placed.y;
+        rowMaxH = 0;
+      }
+      cursorX = placed.x + dw;
+      if (dh > rowMaxH) rowMaxH = dh;
+    }
+
+    occ.mark(placed.x, placed.y, dw, dh);
+    out.set(w.key, { x: placed.x, y: placed.y, w: dw, h: dh });
+  }
+
+  return out;
+}

frontend/src/client/dashboard.ts

@@ -2,6 +2,16 @@ import { initI18n, onLangChange, t, tDyn, getLang, translateEvent } from "./i18n
 import { initSidebar } from "./sidebar";
 import { renderAgendaTimeline, type AgendaItem } from "./agenda-render";
 import { openModal } from "./components/modal";
+import {
+  GRID_COLUMNS,
+  MAX_ROW_SPAN,
+  placeWidgets,
+  clampW as gridClampW,
+  clampH as gridClampH,
+  type PlacedRect,
+  type WidgetPlacementInput,
+  type WidgetSizeBound,
+} from "./dashboard-grid";
 
 interface DashboardUser {
   id: string;
@@ -156,10 +166,9 @@ interface WidgetCatalogEntry {
   settings?: WidgetSettingsSchema | null;
 }
 
-// Grid constants — must match internal/services/dashboard_layout_spec.go
-const GRID_COLUMNS = 12;
-const MAX_ROW_SPAN = 5;
-
+// Grid constants — must match internal/services/dashboard_layout_spec.go.
+// Re-exported from ./dashboard-grid so the placement math is shared with
+// the unit tests; the names below keep the local imports tidy.
 declare global {
   interface Window {
     __PALIAD_DASHBOARD__?: DashboardData | null;
@@ -1937,74 +1946,43 @@ function applyLayout(): void {
   }
 }
 
-// PlacedRect is the resolved grid position for a widget — non-zero w/h,
-// concrete x/y (0-indexed) derived from spec values plus auto-flow
-// fill-in for missing y values.
-interface PlacedRect { x: number; y: number; w: number; h: number; }
-
-// computePlacements assigns explicit grid coordinates to every visible
-// widget. Spec values win when present; missing values fall back to:
-//   - w: catalog default_w, else GRID_COLUMNS
-//   - h: catalog default_h, else 1
-//   - x: 0 when also missing y; else as given
-//   - y: auto-flow — packs left-to-right under the running cursor,
-//        wrapping when the row doesn't fit.
-//
-// Auto-flow keeps pre-overhaul layouts (no positions on the wire)
-// rendering as a tidy single column without the visual mess the old
-// applyLayout produced. Hidden widgets are skipped — they contribute
-// no placement and don't reserve row space.
+// computePlacements is the local adapter — it walks the layout's widgets,
+// resolves each widget's catalog bound, and hands the spec to the pure
+// placeWidgets() in ./dashboard-grid. The pure placer carries the no-
+// overlap invariant: if two widgets request colliding cells (drag-drop
+// swap with mismatched widths, resize-grow into a sibling, etc.) the
+// later one is shifted down to the next free row. See m/paliad#70.
 function computePlacements(widgets: DashboardWidgetRef[]): Map<string, PlacedRect> {
-  const out = new Map<string, PlacedRect>();
-  // Track the tallest widget on the row currently being filled, so
-  // wrapping advances cursorY past the bottom of the row (not just by
-  // the new widget's height — that would let taller previous neighbours
-  // overlap). Mirrors the Go-side packer in FactoryDefaultLayout.
-  let cursorX = 0, cursorY = 0, rowMaxH = 0;
-  for (const w of widgets) {
-    if (!w.visible) continue;
-    const def = lookupCatalog(w.key);
-    const dw = clampW(w.w ?? def?.default_w ?? GRID_COLUMNS, def);
-    const dh = clampH(w.h ?? def?.default_h ?? 1, def);
-    let x = typeof w.x === "number" ? w.x : -1;
-    let y = typeof w.y === "number" ? w.y : -1;
-    if (x < 0) {
-      if (cursorX + dw > GRID_COLUMNS) {
-        cursorY += rowMaxH;
-        cursorX = 0;
-        rowMaxH = 0;
-      }
-      x = cursorX;
-      y = cursorY;
-      cursorX += dw;
-      if (dh > rowMaxH) rowMaxH = dh;
-    } else {
-      // Explicit x/y from the spec — trust it. Don't move the cursor
-      // because explicit positions can land anywhere; auto-flow widgets
-      // are positioned independently.
-      if (y < 0) y = cursorY;
-    }
-    out.set(w.key, { x, y, w: dw, h: dh });
-  }
-  return out;
+  const inputs: WidgetPlacementInput[] = widgets.map((w) => ({
+    key: w.key,
+    visible: w.visible,
+    x: w.x,
+    y: w.y,
+    w: w.w,
+    h: w.h,
+    bound: toBound(lookupCatalog(w.key)),
+  }));
+  return placeWidgets(inputs);
 }
 
 function clampW(w: number, def: WidgetCatalogEntry | undefined): number {
-  let v = Math.round(w);
-  if (!Number.isFinite(v) || v <= 0) v = def?.default_w ?? GRID_COLUMNS;
-  v = Math.max(1, Math.min(GRID_COLUMNS, v));
-  if (def?.min_w && v < def.min_w) v = def.min_w;
-  if (def?.max_w && v > def.max_w) v = def.max_w;
-  return v;
+  return gridClampW(w, toBound(def));
 }
 
 function clampH(h: number, def: WidgetCatalogEntry | undefined): number {
-  let v = Math.round(h);
-  if (!Number.isFinite(v) || v <= 0) v = def?.default_h ?? 1;
-  v = Math.max(1, Math.min(MAX_ROW_SPAN, v));
-  if (def?.min_h && v < def.min_h) v = def.min_h;
-  if (def?.max_h && v > def.max_h) v = def.max_h;
-  return v;
+  return gridClampH(h, toBound(def));
+}
+
+function toBound(def: WidgetCatalogEntry | undefined): WidgetSizeBound | undefined {
+  if (!def) return undefined;
+  return {
+    default_w: def.default_w,
+    default_h: def.default_h,
+    min_w: def.min_w,
+    max_w: def.max_w,
+    min_h: def.min_h,
+    max_h: def.max_h,
+  };
 }
 
 // filterByHorizonDays drops items whose key date is more than `days`