feat: work-in-progress limits and swimlanes on the board

Each status can carry a WIP limit in the project settings; the board shows
it next to the count, marks a column that goes over it and says so when a
card is dropped there. The board can also be grouped in rows by person,
epic, priority or type, remembered per browser.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libs/web/tracker/domain/src/lib/models/swimlanes.spec.ts

@@ -0,0 +1,51 @@
+import { IssuePriority } from './enums';
+import { BoardColumn, IssueSummary } from './models';
+import { overWip, swimlanes } from './swimlanes';
+
+const card = (id: string, assignee: string | null, parent: string | null) =>
+  ({
+    id,
+    assignee: assignee ? { id: assignee, name: assignee } : null,
+    parent: parent ? { id: parent, key: parent, title: parent } : null,
+    priority: IssuePriority.MEDIUM,
+    type: 'TASK',
+  }) as IssueSummary;
+
+const board: BoardColumn[] = [
+  {
+    status: 'TODO',
+    total: 3,
+    issues: [
+      card('a', 'ana', 'e1'),
+      card('b', null, null),
+      card('c', 'bob', 'e1'),
+    ],
+  },
+  { status: 'DONE', total: 1, issues: [card('d', 'ana', null)] },
+];
+
+describe('swimlanes', () => {
+  it('splits the board by person, nobody last', () => {
+    const lanes = swimlanes(board, 'assignee');
+    expect(lanes.map((l) => [l.key, l.count])).toEqual([
+      ['ana', 2],
+      ['bob', 1],
+      ['', 1],
+    ]);
+    expect(lanes[0].columns.map((c) => c.issues.map((i) => i.id))).toEqual([
+      ['a'],
+      ['d'],
+    ]);
+  });
+
+  it('groups by epic and keeps one row when not grouping', () => {
+    expect(swimlanes(board, 'epic').map((l) => l.key)).toEqual(['e1', '']);
+    expect(swimlanes(board, 'none')).toHaveLength(1);
+  });
+
+  it('flags a column over its WIP limit', () => {
+    expect(overWip(4, 3)).toBe(true);
+    expect(overWip(3, 3)).toBe(false);
+    expect(overWip(9, null)).toBe(false);
+  });
+});

libs/web/tracker/domain/src/lib/models/swimlanes.ts

@@ -0,0 +1,72 @@
+import { BoardColumn, IssueSummary } from './models';
+
+/** How the board can be split in rows. */
+export type SwimlaneMode = 'none' | 'assignee' | 'priority' | 'type' | 'epic';
+
+export interface Swimlane {
+  /** Stable key of the row (`''` for "nobody", "no epic"...). */
+  key: string;
+  /** Same columns as the board, each with only this row's cards. */
+  columns: BoardColumn[];
+  count: number;
+}
+
+/** Key of the row a card belongs to. */
+export function laneKeyOf(issue: IssueSummary, mode: SwimlaneMode): string {
+  switch (mode) {
+    case 'assignee':
+      return issue.assignee?.id ?? '';
+    case 'priority':
+      return issue.priority;
+    case 'type':
+      return issue.type;
+    case 'epic':
+      return issue.parent?.id ?? '';
+    default:
+      return '';
+  }
+}
+
+/**
+ * The board's columns split in rows. `order` ranks keys (lower first);
+ * cards keep their order, and the empty key (nobody, no epic) goes last.
+ */
+export function swimlanes(
+  columns: BoardColumn[],
+  mode: SwimlaneMode,
+  order: (key: string) => number = () => 0,
+): Swimlane[] {
+  if (mode === 'none')
+    return [
+      {
+        key: '',
+        columns,
+        count: columns.reduce((sum, c) => sum + c.issues.length, 0),
+      },
+    ];
+  const keys = new Set<string>();
+  for (const column of columns)
+    for (const issue of column.issues) keys.add(laneKeyOf(issue, mode));
+  return [...keys]
+    .sort((a, b) =>
+      a === '' ? 1 : b === '' ? -1 : order(a) - order(b) || a.localeCompare(b),
+    )
+    .map((key) => {
+      const lane = columns.map((column) => {
+        const issues = column.issues.filter(
+          (issue) => laneKeyOf(issue, mode) === key,
+        );
+        return { ...column, issues, total: issues.length };
+      });
+      return {
+        key,
+        columns: lane,
+        count: lane.reduce((sum, c) => sum + c.issues.length, 0),
+      };
+    });
+}
+
+/** Whether a column holds more than its limit (`total` counts all of it). */
+export function overWip(total: number, limit: number | null): boolean {
+  return limit !== null && total > limit;
+}

libs/web/tracker/domain/src/lib/models/workflow.ts

@@ -42,6 +42,8 @@ export interface WorkflowStatus {
   requiresReason: boolean;
   /** No new tickets or transitions into it; existing tickets keep it. */
   archived: boolean;
+  /** Most tickets the column should hold (null/absent: no limit). */
+  wipLimit?: number | null;
 }
 
 export interface StatusTransitions {
@@ -156,6 +158,11 @@ export class Workflow {
     return this.settings.areas.filter((a) => !a.archived);
   }
 
+  /** Most tickets the status should hold (null: no limit). */
+  wipLimit(id: string): number | null {
+    return this.status(id).wipLimit ?? null;
+  }
+
   requiresReason(id: string): boolean {
     return this.status(id).requiresReason;
   }