feat(FN-4360): complete Step 1 — add reliability aggregation helpers

Fusion-Task-Id: FN-4360
Fusion-Task-Lineage: 50e17cef-29b0-4adc-aa1c-bffdebe4b43c

packages/dashboard/src/__tests__/reliability-metrics.test.ts

@@ -0,0 +1,139 @@
+import { describe, expect, it } from "vitest";
+
+import type { ActivityLogEntry, RunAuditEvent } from "@fusion/core";
+
+import {
+  bucketByDay,
+  fileScopeInvariantFailuresPerDay,
+  inReviewDurationMetrics,
+  inReviewFailureRate7d,
+  mergeAttemptsPerMergedTask,
+  postMergeAuditFailuresPerDay,
+  recoverAlreadyMergedReviewTasksRecoveriesPerDay,
+  tasksBouncedToInProgressPerDay,
+  tasksEnteredInReviewPerDay,
+} from "../reliability-metrics";
+
+function moved(timestamp: string, taskId: string, from: string, to: string): ActivityLogEntry {
+  return { id: `${taskId}-${timestamp}`, timestamp, type: "task:moved", taskId, details: "moved", metadata: { from, to } };
+}
+
+describe("reliability-metrics", () => {
+  it("buckets timestamps by UTC day", () => {
+    expect(bucketByDay("2026-05-13T23:59:59.000Z")).toBe("2026-05-13");
+  });
+
+  it("counts in-review entries and bounces per day", () => {
+    const activity: ActivityLogEntry[] = [
+      moved("2026-05-11T10:00:00.000Z", "FN-1", "todo", "in-review"),
+      moved("2026-05-11T11:00:00.000Z", "FN-2", "in-review", "in-progress"),
+      moved("2026-05-12T12:00:00.000Z", "FN-3", "todo", "in-review"),
+    ];
+    const start = Date.parse("2026-05-10T00:00:00.000Z");
+    const end = Date.parse("2026-05-13T00:00:00.000Z");
+
+    expect(tasksEnteredInReviewPerDay(activity, start, end)).toEqual({ "2026-05-11": 1, "2026-05-12": 1 });
+    expect(tasksBouncedToInProgressPerDay(activity, start, end)).toEqual({ "2026-05-11": 1 });
+  });
+
+  it("returns no-audit-coverage for audit-gap metrics", () => {
+    const events: RunAuditEvent[] = [];
+    const start = Date.parse("2026-05-10T00:00:00.000Z");
+    const end = Date.parse("2026-05-13T00:00:00.000Z");
+
+    expect(postMergeAuditFailuresPerDay(events, start, end)).toEqual({ value: null, reason: "no-audit-coverage" });
+    expect(fileScopeInvariantFailuresPerDay(events, start, end)).toEqual({ value: null, reason: "no-audit-coverage" });
+    expect(recoverAlreadyMergedReviewTasksRecoveriesPerDay(events, start, end)).toEqual({ value: null, reason: "no-audit-coverage" });
+  });
+
+  it("computes in-review duration percentiles", () => {
+    const activity: ActivityLogEntry[] = [
+      moved("2026-05-10T10:00:00.000Z", "FN-1", "todo", "in-review"),
+      moved("2026-05-10T11:00:00.000Z", "FN-1", "in-review", "done"),
+      moved("2026-05-10T12:00:00.000Z", "FN-2", "todo", "in-review"),
+      moved("2026-05-10T14:00:00.000Z", "FN-2", "in-review", "done"),
+      moved("2026-05-10T15:00:00.000Z", "FN-3", "todo", "in-review"),
+      moved("2026-05-10T18:00:00.000Z", "FN-3", "in-review", "done"),
+    ];
+
+    const metric = inReviewDurationMetrics(
+      activity,
+      Date.parse("2026-05-10T00:00:00.000Z"),
+      Date.parse("2026-05-11T00:00:00.000Z"),
+    );
+
+    expect(metric.sampleCount).toBe(3);
+    expect(metric.p50Ms).toBe(2 * 60 * 60 * 1000);
+    expect(metric.p95Ms).toBe(3 * 60 * 60 * 1000);
+  });
+
+  it("returns insufficient-samples when too few review exits", () => {
+    const activity: ActivityLogEntry[] = [
+      moved("2026-05-10T10:00:00.000Z", "FN-1", "todo", "in-review"),
+      moved("2026-05-10T11:00:00.000Z", "FN-1", "in-review", "done"),
+    ];
+
+    expect(
+      inReviewDurationMetrics(activity, Date.parse("2026-05-10T00:00:00.000Z"), Date.parse("2026-05-11T00:00:00.000Z")),
+    ).toEqual({ p50Ms: null, p95Ms: null, sampleCount: 1, reason: "insufficient-samples" });
+  });
+
+  it("computes merge attempts per merged task", () => {
+    const events: RunAuditEvent[] = [
+      {
+        id: "1",
+        timestamp: "2026-05-10T10:00:00.000Z",
+        taskId: "FN-1",
+        agentId: "a",
+        runId: "r1",
+        domain: "git",
+        mutationType: "merge:start",
+        target: "FN-1",
+        metadata: { phase: "merge-attempt-1" },
+      },
+      {
+        id: "2",
+        timestamp: "2026-05-10T10:01:00.000Z",
+        taskId: "FN-1",
+        agentId: "a",
+        runId: "r1",
+        domain: "git",
+        mutationType: "merge:start",
+        target: "FN-1",
+        metadata: { phase: "merge-attempt-2" },
+      },
+      {
+        id: "3",
+        timestamp: "2026-05-10T10:00:00.000Z",
+        taskId: "FN-2",
+        agentId: "a",
+        runId: "r2",
+        domain: "git",
+        mutationType: "merge:start",
+        target: "FN-2",
+        metadata: { phase: "merge-attempt-1" },
+      },
+    ];
+
+    const activity: ActivityLogEntry[] = [
+      { id: "m1", timestamp: "2026-05-10T12:00:00.000Z", type: "task:merged", taskId: "FN-1", details: "merged" },
+      { id: "m2", timestamp: "2026-05-10T13:00:00.000Z", type: "task:merged", taskId: "FN-2", details: "merged" },
+    ];
+
+    const metric = mergeAttemptsPerMergedTask(events, activity, Date.parse("2026-05-10T00:00:00.000Z"), Date.parse("2026-05-11T00:00:00.000Z"));
+    expect(metric.mean).toBe(1.5);
+    expect(metric.max).toBe(2);
+    expect(metric.histogram).toEqual({ "1": 1, "2": 1 });
+  });
+
+  it("returns no-audit-coverage when merge attempts cannot be inferred", () => {
+    const metric = mergeAttemptsPerMergedTask([], [], Date.parse("2026-05-10T00:00:00.000Z"), Date.parse("2026-05-11T00:00:00.000Z"));
+    expect(metric).toEqual({ mean: null, max: null, histogram: {}, reason: "no-audit-coverage" });
+  });
+
+  it("computes in-review failure rate and null reason", () => {
+    const endMs = Date.parse("2026-05-13T00:00:00.000Z");
+    expect(inReviewFailureRate7d({ "2026-05-13": 10 }, { "2026-05-13": 2 }, endMs)).toEqual({ value: 0.2 });
+    expect(inReviewFailureRate7d({}, {}, endMs)).toEqual({ value: null, reason: "no-in-review-entries" });
+  });
+});