feat(inbox): add Inbox activity heatmap

packages/core/src/inbox/inboxHeatmap.test.ts

@@ -0,0 +1,275 @@
+import type { SignalReport } from "@posthog/shared/types";
+import { describe, expect, it } from "vitest";
+import {
+  computeInboxHeatmap,
+  DEFAULT_INBOX_HEATMAP_METRIC,
+  INBOX_HEATMAP_METRICS,
+  inboxHeatmapDayKey,
+  inboxHeatmapMonthLabels,
+} from "./inboxHeatmap";
+
+// Midday-UTC timestamps so the local calendar day is stable across the test
+// runner's timezone (any offset from -12h..+14h stays on the same day).
+function fakeReport(overrides: Partial<SignalReport> = {}): SignalReport {
+  return {
+    id: "r1",
+    title: "Test report",
+    summary: "Summary",
+    status: "ready",
+    total_weight: 1,
+    signal_count: 1,
+    created_at: "2026-06-05T12:00:00Z",
+    updated_at: "2026-06-05T12:00:00Z",
+    artefact_count: 0,
+    priority: null,
+    actionability: null,
+    is_suggested_reviewer: false,
+    source_products: [],
+    implementation_pr_url: null,
+    ...overrides,
+  };
+}
+
+const NOW = new Date("2026-06-17T12:00:00Z");
+
+function dayCount(
+  heatmap: ReturnType<typeof computeInboxHeatmap>,
+  dayKey: string,
+): number {
+  for (const week of heatmap.weeks) {
+    for (const day of week.days) {
+      if (day.dayKey === dayKey) return day.count;
+    }
+  }
+  return -1; // day not present in the grid
+}
+
+describe("computeInboxHeatmap", () => {
+  it("counts only pull-request reports for the pull_requests metric", () => {
+    const reports = [
+      fakeReport({ id: "pr1", implementation_pr_url: "https://gh/pr/1" }),
+      fakeReport({ id: "pr2", implementation_pr_url: "https://gh/pr/2" }),
+      fakeReport({ id: "noPr", implementation_pr_url: null }),
+    ];
+
+    const heatmap = computeInboxHeatmap({
+      reports,
+      metric: "pull_requests",
+      now: NOW,
+    });
+
+    expect(heatmap.totalCount).toBe(2);
+    expect(dayCount(heatmap, inboxHeatmapDayKey(new Date(2026, 5, 5)))).toBe(2);
+  });
+
+  it("excludes suppressed and deleted reports from both metrics", () => {
+    const reports = [
+      fakeReport({ id: "ok", implementation_pr_url: "https://gh/pr/1" }),
+      fakeReport({
+        id: "suppressed",
+        status: "suppressed",
+        implementation_pr_url: "https://gh/pr/2",
+      }),
+      fakeReport({ id: "deleted", status: "deleted" }),
+    ];
+
+    const pulls = computeInboxHeatmap({
+      reports,
+      metric: "pull_requests",
+      now: NOW,
+    });
+    const created = computeInboxHeatmap({
+      reports,
+      metric: "reports_created",
+      now: NOW,
+    });
+
+    expect(pulls.totalCount).toBe(1);
+    // reports_created counts the one non-excluded report (the PR one); the
+    // suppressed and deleted reports are out of the inbox entirely.
+    expect(created.totalCount).toBe(1);
+  });
+
+  it("does not treat status:ready as a merge/landed signal — a ready report with no PR is not counted by pull_requests", () => {
+    const reports = [
+      fakeReport({ status: "ready", implementation_pr_url: null }),
+    ];
+
+    const pulls = computeInboxHeatmap({
+      reports,
+      metric: "pull_requests",
+      now: NOW,
+    });
+
+    expect(pulls.totalCount).toBe(0);
+  });
+
+  it("buckets reports by created_at day, not updated_at", () => {
+    const reports = [
+      fakeReport({
+        id: "pr",
+        implementation_pr_url: "https://gh/pr/1",
+        created_at: "2026-06-10T12:00:00Z",
+        updated_at: "2026-06-16T12:00:00Z",
+      }),
+    ];
+
+    const heatmap = computeInboxHeatmap({
+      reports,
+      metric: "pull_requests",
+      now: NOW,
+    });
+
+    expect(dayCount(heatmap, inboxHeatmapDayKey(new Date(2026, 5, 10)))).toBe(
+      1,
+    );
+    expect(dayCount(heatmap, inboxHeatmapDayKey(new Date(2026, 5, 16)))).toBe(
+      0,
+    );
+  });
+
+  it("renders a Sunday-aligned grid of the requested number of weeks", () => {
+    const heatmap = computeInboxHeatmap({
+      reports: [],
+      metric: "pull_requests",
+      now: NOW,
+      weeks: 53,
+    });
+
+    expect(heatmap.weeks).toHaveLength(53);
+    for (const week of heatmap.weeks) {
+      expect(week.days).toHaveLength(7);
+      expect(week.days[0]?.date.getDay()).toBe(0); // Sunday
+    }
+    // Last column contains today.
+    const lastWeek = heatmap.weeks[heatmap.weeks.length - 1];
+    const todayKey = inboxHeatmapDayKey(new Date(2026, 5, 17));
+    expect(lastWeek?.days.some((d) => d.dayKey === todayKey)).toBe(true);
+  });
+
+  it("marks days after today as future and never counts them", () => {
+    // 2026-06-17 is a Wednesday, so Thu–Sat of the last column are in the future.
+    const heatmap = computeInboxHeatmap({
+      reports: [],
+      metric: "pull_requests",
+      now: NOW,
+    });
+    const lastWeek = heatmap.weeks[heatmap.weeks.length - 1];
+    const futureDays = lastWeek?.days.filter((d) => d.isFuture) ?? [];
+    expect(futureDays).toHaveLength(3);
+    for (const day of futureDays) {
+      expect(day.count).toBe(0);
+      expect(day.level).toBe(0);
+    }
+  });
+
+  it("drops reports created before the rendered window", () => {
+    const reports = [
+      fakeReport({
+        id: "ancient",
+        implementation_pr_url: "https://gh/pr/1",
+        created_at: "2024-01-01T12:00:00Z",
+      }),
+    ];
+
+    const heatmap = computeInboxHeatmap({
+      reports,
+      metric: "pull_requests",
+      now: NOW,
+      weeks: 53,
+    });
+
+    expect(heatmap.totalCount).toBe(0);
+  });
+
+  it("assigns the busiest day level 4 and lighter days lower levels", () => {
+    const reports = [
+      // 3 PRs on Jun 10 (busiest), 1 PR on Jun 5.
+      ...Array.from({ length: 3 }, (_, i) =>
+        fakeReport({
+          id: `busy${i}`,
+          implementation_pr_url: `https://gh/pr/busy${i}`,
+          created_at: "2026-06-10T12:00:00Z",
+        }),
+      ),
+      fakeReport({
+        id: "light",
+        implementation_pr_url: "https://gh/pr/light",
+        created_at: "2026-06-05T12:00:00Z",
+      }),
+    ];
+
+    const heatmap = computeInboxHeatmap({
+      reports,
+      metric: "pull_requests",
+      now: NOW,
+    });
+
+    expect(heatmap.maxCount).toBe(3);
+    expect(heatmap.activeDays).toBe(2);
+    expect(heatmap.totalCount).toBe(4);
+
+    const findLevel = (date: Date) => {
+      const key = inboxHeatmapDayKey(date);
+      for (const week of heatmap.weeks) {
+        for (const day of week.days) if (day.dayKey === key) return day.level;
+      }
+      return -1;
+    };
+    expect(findLevel(new Date(2026, 5, 10))).toBe(4);
+    expect(findLevel(new Date(2026, 5, 5))).toBe(2); // ceil(1/3 * 4) = 2
+  });
+
+  it("reports zero activity cleanly for an empty inbox", () => {
+    const heatmap = computeInboxHeatmap({
+      reports: [],
+      metric: DEFAULT_INBOX_HEATMAP_METRIC,
+      now: NOW,
+    });
+    expect(heatmap.totalCount).toBe(0);
+    expect(heatmap.activeDays).toBe(0);
+    expect(heatmap.maxCount).toBe(0);
+    for (const week of heatmap.weeks) {
+      for (const day of week.days) expect(day.level).toBe(0);
+    }
+  });
+});
+
+describe("INBOX_HEATMAP_METRICS", () => {
+  it("defaults to pull requests", () => {
+    expect(DEFAULT_INBOX_HEATMAP_METRIC).toBe("pull_requests");
+  });
+
+  it("each metric's includes predicate is exposed", () => {
+    expect(
+      INBOX_HEATMAP_METRICS.pull_requests.includes(
+        fakeReport({ implementation_pr_url: "https://gh/pr/1" }),
+      ),
+    ).toBe(true);
+    expect(
+      INBOX_HEATMAP_METRICS.reports_created.includes(
+        fakeReport({ status: "suppressed" }),
+      ),
+    ).toBe(false);
+  });
+});
+
+describe("inboxHeatmapMonthLabels", () => {
+  it("emits one label per month boundary in column order", () => {
+    const heatmap = computeInboxHeatmap({
+      reports: [],
+      metric: "pull_requests",
+      now: NOW,
+      weeks: 53,
+    });
+    const labels = inboxHeatmapMonthLabels(heatmap, "en-US");
+
+    expect(labels.length).toBeGreaterThan(0);
+    // Week indices strictly increasing.
+    for (let i = 1; i < labels.length; i++) {
+      expect(labels[i]?.weekIndex).toBeGreaterThan(labels[i - 1]?.weekIndex);
+    }
+    // The final label should be the current month (June).
+    expect(labels[labels.length - 1]?.label).toBe("Jun");
+  });
+});