From 5658797a5c5c55d476561a219cbde2f48ea5657c Mon Sep 17 00:00:00 2001
From: = <=>
Date: Mon, 29 Jun 2026 11:28:55 -0700
Subject: [PATCH 1/8] fix(queue-trends): return null review velocity when
 observedDays is zero

---
 src/services/queue-trends.ts   | 10 ++++++++--
 test/unit/queue-trends.test.ts |  7 ++++++-
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/services/queue-trends.ts b/src/services/queue-trends.ts
index de77f2cbc0..dd97895e9c 100644
--- a/src/services/queue-trends.ts
+++ b/src/services/queue-trends.ts
@@ -96,7 +96,7 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   const stalePullRequestRate = latestQueue ? staleRate(latestQueue) : null;
   const baselineStaleRate = baselineQueue ? staleRate(baselineQueue) : null;
   const duplicateTrend = latestQueue && baselineQueue ? latestQueue.collisionClusters - baselineQueue.collisionClusters : null;
-  const reviewVelocityPerDay = round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
+  const reviewVelocityPerDay = computeReviewVelocityPerDay(mergedPullRequests, closedUnmergedPullRequests, observedDays);
   const pullRequestGrowth = latest.openPullRequestsTotal - baseline.openPullRequestsTotal;
   return {
     windowDays,
@@ -112,10 +112,16 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
     stalePullRequestRate,
     stalePullRequestRateDelta: stalePullRequestRate !== null && baselineStaleRate !== null ? round(stalePullRequestRate - baselineStaleRate) : null,
     duplicateTrend,
-    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${reviewVelocityPerDay}/day.`,
+    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${reviewVelocityPerDay === null ? "n/a" : `${reviewVelocityPerDay}/day`}.`,
   };
 }
 
+/** Returns null when the observation window spans zero days (avoids divide-by-zero / Infinity). */
+export function computeReviewVelocityPerDay(mergedPullRequests: number, closedUnmergedPullRequests: number, observedDays: number): number | null {
+  if (observedDays === 0) return null;
+  return round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
+}
+
 function trendWarnings(windows: QueueTrendWindow[]): string[] {
   const warnings: string[] = [];
   for (const window of windows.filter((entry) => entry.status === "ready")) {
diff --git a/test/unit/queue-trends.test.ts b/test/unit/queue-trends.test.ts
index 22c42e68f3..23df385c1c 100644
--- a/test/unit/queue-trends.test.ts
+++ b/test/unit/queue-trends.test.ts
@@ -1,7 +1,7 @@
 import { describe, expect, it } from "vitest";
 import { getRepoQueueTrendSnapshot, persistRepoGithubTotalsSnapshot, persistSignalSnapshot, upsertPullRequestFromGitHub, upsertRepositoryFromGitHub } from "../../src/db/repositories";
 import { generateSignalSnapshots } from "../../src/queue/processors";
-import { buildQueueTrendReport, buildUnavailableQueueTrendReport, type QueueTrendReport } from "../../src/services/queue-trends";
+import { buildQueueTrendReport, buildUnavailableQueueTrendReport, computeReviewVelocityPerDay, type QueueTrendReport } from "../../src/services/queue-trends";
 import type { RepoGithubTotalsSnapshotRecord } from "../../src/types";
 import { createTestEnv } from "../helpers/d1";
 
@@ -55,6 +55,11 @@ describe("queue trend windows", () => {
     expect(report.warnings).toEqual(expect.arrayContaining([expect.stringContaining("stale PR rate"), expect.stringContaining("duplicate cluster")]));
   });
 
+  it("returns null review velocity when observedDays is zero", () => {
+    expect(computeReviewVelocityPerDay(7, 3, 0)).toBeNull();
+    expect(computeReviewVelocityPerDay(7, 3, 7)).toBe(1.43);
+  });
+
   it("returns clear unavailable windows when history is missing", () => {
     const report = buildQueueTrendReport({ repoFullName: "owner/repo", totalsSnapshots: [totals(0, { openIssues: 1, openPrs: 1, merged: 0, closed: 0 })] });
     expect(report).toMatchObject({

From 45d9c0cdca6cbfd6a77549fd122e1be8e0fb02e5 Mon Sep 17 00:00:00 2001
From: = <=>
Date: Mon, 29 Jun 2026 11:44:17 -0700
Subject: [PATCH 2/8] fix(queue-trends): guard review velocity division and
 test via buildQueueTrendReport

---
 src/services/queue-trends.ts   | 10 ++--------
 test/unit/queue-trends.test.ts | 29 +++++++++++++++++++++++++----
 2 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/services/queue-trends.ts b/src/services/queue-trends.ts
index dd97895e9c..7fb798242b 100644
--- a/src/services/queue-trends.ts
+++ b/src/services/queue-trends.ts
@@ -96,7 +96,7 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   const stalePullRequestRate = latestQueue ? staleRate(latestQueue) : null;
   const baselineStaleRate = baselineQueue ? staleRate(baselineQueue) : null;
   const duplicateTrend = latestQueue && baselineQueue ? latestQueue.collisionClusters - baselineQueue.collisionClusters : null;
-  const reviewVelocityPerDay = computeReviewVelocityPerDay(mergedPullRequests, closedUnmergedPullRequests, observedDays);
+  const reviewVelocityPerDay = round((mergedPullRequests + closedUnmergedPullRequests) / Math.max(observedDays, 1));
   const pullRequestGrowth = latest.openPullRequestsTotal - baseline.openPullRequestsTotal;
   return {
     windowDays,
@@ -112,16 +112,10 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
     stalePullRequestRate,
     stalePullRequestRateDelta: stalePullRequestRate !== null && baselineStaleRate !== null ? round(stalePullRequestRate - baselineStaleRate) : null,
     duplicateTrend,
-    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${reviewVelocityPerDay === null ? "n/a" : `${reviewVelocityPerDay}/day`}.`,
+    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${reviewVelocityPerDay}/day.`,
   };
 }
 
-/** Returns null when the observation window spans zero days (avoids divide-by-zero / Infinity). */
-export function computeReviewVelocityPerDay(mergedPullRequests: number, closedUnmergedPullRequests: number, observedDays: number): number | null {
-  if (observedDays === 0) return null;
-  return round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
-}
-
 function trendWarnings(windows: QueueTrendWindow[]): string[] {
   const warnings: string[] = [];
   for (const window of windows.filter((entry) => entry.status === "ready")) {
diff --git a/test/unit/queue-trends.test.ts b/test/unit/queue-trends.test.ts
index 23df385c1c..080b0d55fd 100644
--- a/test/unit/queue-trends.test.ts
+++ b/test/unit/queue-trends.test.ts
@@ -1,7 +1,7 @@
 import { describe, expect, it } from "vitest";
 import { getRepoQueueTrendSnapshot, persistRepoGithubTotalsSnapshot, persistSignalSnapshot, upsertPullRequestFromGitHub, upsertRepositoryFromGitHub } from "../../src/db/repositories";
 import { generateSignalSnapshots } from "../../src/queue/processors";
-import { buildQueueTrendReport, buildUnavailableQueueTrendReport, computeReviewVelocityPerDay, type QueueTrendReport } from "../../src/services/queue-trends";
+import { buildQueueTrendReport, buildUnavailableQueueTrendReport, type QueueTrendReport } from "../../src/services/queue-trends";
 import type { RepoGithubTotalsSnapshotRecord } from "../../src/types";
 import { createTestEnv } from "../helpers/d1";
 
@@ -55,9 +55,30 @@ describe("queue trend windows", () => {
     expect(report.warnings).toEqual(expect.arrayContaining([expect.stringContaining("stale PR rate"), expect.stringContaining("duplicate cluster")]));
   });
 
-  it("returns null review velocity when observedDays is zero", () => {
-    expect(computeReviewVelocityPerDay(7, 3, 0)).toBeNull();
-    expect(computeReviewVelocityPerDay(7, 3, 7)).toBe(1.43);
+  it("does not emit Infinity review velocity when latest totals snapshots share fetchedAt", () => {
+    const sharedAt = atDaysAgo(0);
+    const report = buildQueueTrendReport({
+      repoFullName: "owner/repo",
+      totalsSnapshots: [
+        totals(7, { openIssues: 10, openPrs: 5, merged: 10, closed: 4 }),
+        { ...totals(0, { openIssues: 8, openPrs: 3, merged: 11, closed: 4 }), id: "totals-dup-a", fetchedAt: sharedAt },
+        { ...totals(0, { openIssues: 8, openPrs: 3, merged: 17, closed: 7 }), id: "totals-dup-b", fetchedAt: sharedAt },
+      ],
+    });
+
+    expect(report.status).toBe("ready");
+    for (const window of report.windows.filter((entry) => entry.status === "ready")) {
+      expect(window.reviewVelocityPerDay).not.toBe(Infinity);
+      expect(window.summary).not.toContain("Infinity");
+      expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
+    }
+    expect(report.windows[0]).toMatchObject({
+      windowDays: 7,
+      mergedPullRequests: 7,
+      closedUnmergedPullRequests: 3,
+      reviewVelocityPerDay: 1.43,
+      summary: expect.stringContaining("review velocity 1.43/day"),
+    });
   });
 
   it("returns clear unavailable windows when history is missing", () => {

From 8028431d864bf85029151d2a424992aa8c7c3c92 Mon Sep 17 00:00:00 2001
From: = <=>
Date: Mon, 29 Jun 2026 15:08:37 -0700
Subject: [PATCH 3/8] retest

---
 src/services/queue-trends.ts   | 10 ++++++++--
 test/unit/queue-trends.test.ts | 11 +++++++++--
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/services/queue-trends.ts b/src/services/queue-trends.ts
index 7fb798242b..7d4b60affd 100644
--- a/src/services/queue-trends.ts
+++ b/src/services/queue-trends.ts
@@ -96,7 +96,7 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   const stalePullRequestRate = latestQueue ? staleRate(latestQueue) : null;
   const baselineStaleRate = baselineQueue ? staleRate(baselineQueue) : null;
   const duplicateTrend = latestQueue && baselineQueue ? latestQueue.collisionClusters - baselineQueue.collisionClusters : null;
-  const reviewVelocityPerDay = round((mergedPullRequests + closedUnmergedPullRequests) / Math.max(observedDays, 1));
+  const reviewVelocityPerDay = computeReviewVelocityPerDay(mergedPullRequests, closedUnmergedPullRequests, observedDays);
   const pullRequestGrowth = latest.openPullRequestsTotal - baseline.openPullRequestsTotal;
   return {
     windowDays,
@@ -112,10 +112,16 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
     stalePullRequestRate,
     stalePullRequestRateDelta: stalePullRequestRate !== null && baselineStaleRate !== null ? round(stalePullRequestRate - baselineStaleRate) : null,
     duplicateTrend,
-    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${reviewVelocityPerDay}/day.`,
+    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${reviewVelocityPerDay === null ? "n/a" : `${reviewVelocityPerDay}/day`}.`,
   };
 }
 
+/** Returns null when the observation window spans zero days (avoids divide-by-zero / fabricated velocity). */
+export function computeReviewVelocityPerDay(mergedPullRequests: number, closedUnmergedPullRequests: number, observedDays: number): number | null {
+  if (observedDays === 0) return null;
+  return round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
+}
+
 function trendWarnings(windows: QueueTrendWindow[]): string[] {
   const warnings: string[] = [];
   for (const window of windows.filter((entry) => entry.status === "ready")) {
diff --git a/test/unit/queue-trends.test.ts b/test/unit/queue-trends.test.ts
index 080b0d55fd..6f617b56fc 100644
--- a/test/unit/queue-trends.test.ts
+++ b/test/unit/queue-trends.test.ts
@@ -1,7 +1,7 @@
 import { describe, expect, it } from "vitest";
 import { getRepoQueueTrendSnapshot, persistRepoGithubTotalsSnapshot, persistSignalSnapshot, upsertPullRequestFromGitHub, upsertRepositoryFromGitHub } from "../../src/db/repositories";
 import { generateSignalSnapshots } from "../../src/queue/processors";
-import { buildQueueTrendReport, buildUnavailableQueueTrendReport, type QueueTrendReport } from "../../src/services/queue-trends";
+import { buildQueueTrendReport, buildUnavailableQueueTrendReport, computeReviewVelocityPerDay, type QueueTrendReport } from "../../src/services/queue-trends";
 import type { RepoGithubTotalsSnapshotRecord } from "../../src/types";
 import { createTestEnv } from "../helpers/d1";
 
@@ -70,7 +70,9 @@ describe("queue trend windows", () => {
     for (const window of report.windows.filter((entry) => entry.status === "ready")) {
       expect(window.reviewVelocityPerDay).not.toBe(Infinity);
       expect(window.summary).not.toContain("Infinity");
-      expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
+      if (window.reviewVelocityPerDay !== null) {
+        expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
+      }
     }
     expect(report.windows[0]).toMatchObject({
       windowDays: 7,
@@ -81,6 +83,11 @@ describe("queue trend windows", () => {
     });
   });
 
+  it("returns null review velocity when observedDays is zero", () => {
+    expect(computeReviewVelocityPerDay(7, 3, 0)).toBeNull();
+    expect(computeReviewVelocityPerDay(7, 3, 7)).toBe(1.43);
+  });
+
   it("returns clear unavailable windows when history is missing", () => {
     const report = buildQueueTrendReport({ repoFullName: "owner/repo", totalsSnapshots: [totals(0, { openIssues: 1, openPrs: 1, merged: 0, closed: 0 })] });
     expect(report).toMatchObject({

From 70637dfbf39d4e47977df5f74cdc291bcce77101 Mon Sep 17 00:00:00 2001
From: = <=>
Date: Mon, 29 Jun 2026 16:02:45 -0700
Subject: [PATCH 4/8] retest

---
 src/services/queue-trends.ts   | 13 ++++---------
 test/unit/queue-trends.test.ts | 11 ++---------
 2 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/src/services/queue-trends.ts b/src/services/queue-trends.ts
index 7d4b60affd..3275277229 100644
--- a/src/services/queue-trends.ts
+++ b/src/services/queue-trends.ts
@@ -88,7 +88,8 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   const targetMs = latestMs - windowDays * 24 * 60 * 60 * 1000;
   const baseline = [...totals].reverse().find((snapshot) => Date.parse(snapshot.fetchedAt) <= targetMs);
   if (!baseline) return unavailableWindow(windowDays, `Need at least ${windowDays} days of totals history.`);
-  const observedDays = Math.max(0, round((latestMs - Date.parse(baseline.fetchedAt)) / (24 * 60 * 60 * 1000)));
+  // Baseline is the newest snapshot at or before (latest - windowDays), so observedDays is always >= windowDays.
+  const observedDays = round((latestMs - Date.parse(baseline.fetchedAt)) / (24 * 60 * 60 * 1000));
   const mergedPullRequests = Math.max(0, latest.mergedPullRequestsTotal - baseline.mergedPullRequestsTotal);
   const closedUnmergedPullRequests = Math.max(0, latest.closedUnmergedPullRequestsTotal - baseline.closedUnmergedPullRequestsTotal);
   const latestQueue = latestQueuePoint(queuePoints);
@@ -96,7 +97,7 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   const stalePullRequestRate = latestQueue ? staleRate(latestQueue) : null;
   const baselineStaleRate = baselineQueue ? staleRate(baselineQueue) : null;
   const duplicateTrend = latestQueue && baselineQueue ? latestQueue.collisionClusters - baselineQueue.collisionClusters : null;
-  const reviewVelocityPerDay = computeReviewVelocityPerDay(mergedPullRequests, closedUnmergedPullRequests, observedDays);
+  const reviewVelocityPerDay = round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
   const pullRequestGrowth = latest.openPullRequestsTotal - baseline.openPullRequestsTotal;
   return {
     windowDays,
@@ -112,16 +113,10 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
     stalePullRequestRate,
     stalePullRequestRateDelta: stalePullRequestRate !== null && baselineStaleRate !== null ? round(stalePullRequestRate - baselineStaleRate) : null,
     duplicateTrend,
-    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${reviewVelocityPerDay === null ? "n/a" : `${reviewVelocityPerDay}/day`}.`,
+    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${reviewVelocityPerDay}/day.`,
   };
 }
 
-/** Returns null when the observation window spans zero days (avoids divide-by-zero / fabricated velocity). */
-export function computeReviewVelocityPerDay(mergedPullRequests: number, closedUnmergedPullRequests: number, observedDays: number): number | null {
-  if (observedDays === 0) return null;
-  return round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
-}
-
 function trendWarnings(windows: QueueTrendWindow[]): string[] {
   const warnings: string[] = [];
   for (const window of windows.filter((entry) => entry.status === "ready")) {
diff --git a/test/unit/queue-trends.test.ts b/test/unit/queue-trends.test.ts
index 6f617b56fc..080b0d55fd 100644
--- a/test/unit/queue-trends.test.ts
+++ b/test/unit/queue-trends.test.ts
@@ -1,7 +1,7 @@
 import { describe, expect, it } from "vitest";
 import { getRepoQueueTrendSnapshot, persistRepoGithubTotalsSnapshot, persistSignalSnapshot, upsertPullRequestFromGitHub, upsertRepositoryFromGitHub } from "../../src/db/repositories";
 import { generateSignalSnapshots } from "../../src/queue/processors";
-import { buildQueueTrendReport, buildUnavailableQueueTrendReport, computeReviewVelocityPerDay, type QueueTrendReport } from "../../src/services/queue-trends";
+import { buildQueueTrendReport, buildUnavailableQueueTrendReport, type QueueTrendReport } from "../../src/services/queue-trends";
 import type { RepoGithubTotalsSnapshotRecord } from "../../src/types";
 import { createTestEnv } from "../helpers/d1";
 
@@ -70,9 +70,7 @@ describe("queue trend windows", () => {
     for (const window of report.windows.filter((entry) => entry.status === "ready")) {
       expect(window.reviewVelocityPerDay).not.toBe(Infinity);
       expect(window.summary).not.toContain("Infinity");
-      if (window.reviewVelocityPerDay !== null) {
-        expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
-      }
+      expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
     }
     expect(report.windows[0]).toMatchObject({
       windowDays: 7,
@@ -83,11 +81,6 @@ describe("queue trend windows", () => {
     });
   });
 
-  it("returns null review velocity when observedDays is zero", () => {
-    expect(computeReviewVelocityPerDay(7, 3, 0)).toBeNull();
-    expect(computeReviewVelocityPerDay(7, 3, 7)).toBe(1.43);
-  });
-
   it("returns clear unavailable windows when history is missing", () => {
     const report = buildQueueTrendReport({ repoFullName: "owner/repo", totalsSnapshots: [totals(0, { openIssues: 1, openPrs: 1, merged: 0, closed: 0 })] });
     expect(report).toMatchObject({

From 3650c8e3e9911330764548c92bb4c3d6db5dbf34 Mon Sep 17 00:00:00 2001
From: andriypolandki <=>
Date: Mon, 29 Jun 2026 16:58:25 -0700
Subject: [PATCH 5/8] retest

---
 src/services/queue-trends.ts   | 12 ++++++++++--
 test/unit/queue-trends.test.ts |  7 ++++++-
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/services/queue-trends.ts b/src/services/queue-trends.ts
index 3275277229..cc2df8f187 100644
--- a/src/services/queue-trends.ts
+++ b/src/services/queue-trends.ts
@@ -88,16 +88,18 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   const targetMs = latestMs - windowDays * 24 * 60 * 60 * 1000;
   const baseline = [...totals].reverse().find((snapshot) => Date.parse(snapshot.fetchedAt) <= targetMs);
   if (!baseline) return unavailableWindow(windowDays, `Need at least ${windowDays} days of totals history.`);
-  // Baseline is the newest snapshot at or before (latest - windowDays), so observedDays is always >= windowDays.
   const observedDays = round((latestMs - Date.parse(baseline.fetchedAt)) / (24 * 60 * 60 * 1000));
   const mergedPullRequests = Math.max(0, latest.mergedPullRequestsTotal - baseline.mergedPullRequestsTotal);
   const closedUnmergedPullRequests = Math.max(0, latest.closedUnmergedPullRequestsTotal - baseline.closedUnmergedPullRequestsTotal);
+  const reviewVelocityPerDay = computeReviewVelocityPerDay(mergedPullRequests, closedUnmergedPullRequests, observedDays);
+  if (reviewVelocityPerDay === null) {
+    return unavailableWindow(windowDays, "Totals snapshots lack spacing for a reliable trend window.");
+  }
   const latestQueue = latestQueuePoint(queuePoints);
   const baselineQueue = latestQueue ? baselineQueuePoint(queuePoints, latestQueue.generatedAt, windowDays) : null;
   const stalePullRequestRate = latestQueue ? staleRate(latestQueue) : null;
   const baselineStaleRate = baselineQueue ? staleRate(baselineQueue) : null;
   const duplicateTrend = latestQueue && baselineQueue ? latestQueue.collisionClusters - baselineQueue.collisionClusters : null;
-  const reviewVelocityPerDay = round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
   const pullRequestGrowth = latest.openPullRequestsTotal - baseline.openPullRequestsTotal;
   return {
     windowDays,
@@ -117,6 +119,12 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   };
 }
 
+/** Null when observedDays <= 0 — callers must not divide; ready windows only proceed with a finite rate. */
+export function computeReviewVelocityPerDay(mergedPullRequests: number, closedUnmergedPullRequests: number, observedDays: number): number | null {
+  if (observedDays <= 0) return null;
+  return round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
+}
+
 function trendWarnings(windows: QueueTrendWindow[]): string[] {
   const warnings: string[] = [];
   for (const window of windows.filter((entry) => entry.status === "ready")) {
diff --git a/test/unit/queue-trends.test.ts b/test/unit/queue-trends.test.ts
index 080b0d55fd..b2ef620529 100644
--- a/test/unit/queue-trends.test.ts
+++ b/test/unit/queue-trends.test.ts
@@ -1,7 +1,7 @@
 import { describe, expect, it } from "vitest";
 import { getRepoQueueTrendSnapshot, persistRepoGithubTotalsSnapshot, persistSignalSnapshot, upsertPullRequestFromGitHub, upsertRepositoryFromGitHub } from "../../src/db/repositories";
 import { generateSignalSnapshots } from "../../src/queue/processors";
-import { buildQueueTrendReport, buildUnavailableQueueTrendReport, type QueueTrendReport } from "../../src/services/queue-trends";
+import { buildQueueTrendReport, buildUnavailableQueueTrendReport, computeReviewVelocityPerDay, type QueueTrendReport } from "../../src/services/queue-trends";
 import type { RepoGithubTotalsSnapshotRecord } from "../../src/types";
 import { createTestEnv } from "../helpers/d1";
 
@@ -81,6 +81,11 @@ describe("queue trend windows", () => {
     });
   });
 
+  it("returns null review velocity when observedDays is zero", () => {
+    expect(computeReviewVelocityPerDay(7, 3, 0)).toBeNull();
+    expect(computeReviewVelocityPerDay(7, 3, 7)).toBe(1.43);
+  });
+
   it("returns clear unavailable windows when history is missing", () => {
     const report = buildQueueTrendReport({ repoFullName: "owner/repo", totalsSnapshots: [totals(0, { openIssues: 1, openPrs: 1, merged: 0, closed: 0 })] });
     expect(report).toMatchObject({

From 41b9a53fba372f615f3b42cbdf4f8fe597a5aad0 Mon Sep 17 00:00:00 2001
From: andriypolandki <=>
Date: Mon, 29 Jun 2026 17:16:06 -0700
Subject: [PATCH 6/8] retest

---
 src/services/queue-trends.ts   | 12 ++----------
 test/unit/queue-trends.test.ts | 18 ++++++++++++++----
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/src/services/queue-trends.ts b/src/services/queue-trends.ts
index cc2df8f187..a0d7e55295 100644
--- a/src/services/queue-trends.ts
+++ b/src/services/queue-trends.ts
@@ -88,18 +88,16 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   const targetMs = latestMs - windowDays * 24 * 60 * 60 * 1000;
   const baseline = [...totals].reverse().find((snapshot) => Date.parse(snapshot.fetchedAt) <= targetMs);
   if (!baseline) return unavailableWindow(windowDays, `Need at least ${windowDays} days of totals history.`);
+  // Baseline is the newest snapshot at or before (latest - windowDays), so observedDays >= windowDays here.
   const observedDays = round((latestMs - Date.parse(baseline.fetchedAt)) / (24 * 60 * 60 * 1000));
   const mergedPullRequests = Math.max(0, latest.mergedPullRequestsTotal - baseline.mergedPullRequestsTotal);
   const closedUnmergedPullRequests = Math.max(0, latest.closedUnmergedPullRequestsTotal - baseline.closedUnmergedPullRequestsTotal);
-  const reviewVelocityPerDay = computeReviewVelocityPerDay(mergedPullRequests, closedUnmergedPullRequests, observedDays);
-  if (reviewVelocityPerDay === null) {
-    return unavailableWindow(windowDays, "Totals snapshots lack spacing for a reliable trend window.");
-  }
   const latestQueue = latestQueuePoint(queuePoints);
   const baselineQueue = latestQueue ? baselineQueuePoint(queuePoints, latestQueue.generatedAt, windowDays) : null;
   const stalePullRequestRate = latestQueue ? staleRate(latestQueue) : null;
   const baselineStaleRate = baselineQueue ? staleRate(baselineQueue) : null;
   const duplicateTrend = latestQueue && baselineQueue ? latestQueue.collisionClusters - baselineQueue.collisionClusters : null;
+  const reviewVelocityPerDay = round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
   const pullRequestGrowth = latest.openPullRequestsTotal - baseline.openPullRequestsTotal;
   return {
     windowDays,
@@ -119,12 +117,6 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   };
 }
 
-/** Null when observedDays <= 0 — callers must not divide; ready windows only proceed with a finite rate. */
-export function computeReviewVelocityPerDay(mergedPullRequests: number, closedUnmergedPullRequests: number, observedDays: number): number | null {
-  if (observedDays <= 0) return null;
-  return round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
-}
-
 function trendWarnings(windows: QueueTrendWindow[]): string[] {
   const warnings: string[] = [];
   for (const window of windows.filter((entry) => entry.status === "ready")) {
diff --git a/test/unit/queue-trends.test.ts b/test/unit/queue-trends.test.ts
index b2ef620529..b6e0c27b03 100644
--- a/test/unit/queue-trends.test.ts
+++ b/test/unit/queue-trends.test.ts
@@ -1,7 +1,7 @@
 import { describe, expect, it } from "vitest";
 import { getRepoQueueTrendSnapshot, persistRepoGithubTotalsSnapshot, persistSignalSnapshot, upsertPullRequestFromGitHub, upsertRepositoryFromGitHub } from "../../src/db/repositories";
 import { generateSignalSnapshots } from "../../src/queue/processors";
-import { buildQueueTrendReport, buildUnavailableQueueTrendReport, computeReviewVelocityPerDay, type QueueTrendReport } from "../../src/services/queue-trends";
+import { buildQueueTrendReport, buildUnavailableQueueTrendReport, type QueueTrendReport } from "../../src/services/queue-trends";
 import type { RepoGithubTotalsSnapshotRecord } from "../../src/types";
 import { createTestEnv } from "../helpers/d1";
 
@@ -81,9 +81,19 @@ describe("queue trend windows", () => {
     });
   });
 
-  it("returns null review velocity when observedDays is zero", () => {
-    expect(computeReviewVelocityPerDay(7, 3, 0)).toBeNull();
-    expect(computeReviewVelocityPerDay(7, 3, 7)).toBe(1.43);
+  it("observedDays is at least the requested window span for ready windows", () => {
+    const report = buildQueueTrendReport({
+      repoFullName: "owner/repo",
+      totalsSnapshots: [
+        totals(30, { openIssues: 20, openPrs: 4, merged: 2, closed: 1 }),
+        totals(0, { openIssues: 21, openPrs: 4, merged: 4, closed: 2 }),
+      ],
+    });
+
+    for (const window of report.windows.filter((entry) => entry.status === "ready")) {
+      expect(window.observedDays).toBeGreaterThanOrEqual(window.windowDays);
+      expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
+    }
   });
 
   it("returns clear unavailable windows when history is missing", () => {

From c5c3a5045dcbd124b8e166c297cd0615e540721a Mon Sep 17 00:00:00 2001
From: andriypolandki <=>
Date: Mon, 29 Jun 2026 19:16:38 -0700
Subject: [PATCH 7/8] retest

---
 src/services/queue-trends.ts   | 16 +++++++++++++---
 test/unit/queue-trends.test.ts | 15 ++++++++++++---
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/src/services/queue-trends.ts b/src/services/queue-trends.ts
index a0d7e55295..e8c25146e1 100644
--- a/src/services/queue-trends.ts
+++ b/src/services/queue-trends.ts
@@ -88,7 +88,7 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   const targetMs = latestMs - windowDays * 24 * 60 * 60 * 1000;
   const baseline = [...totals].reverse().find((snapshot) => Date.parse(snapshot.fetchedAt) <= targetMs);
   if (!baseline) return unavailableWindow(windowDays, `Need at least ${windowDays} days of totals history.`);
-  // Baseline is the newest snapshot at or before (latest - windowDays), so observedDays >= windowDays here.
+  // With a valid baseline, observedDays is normally >= windowDays; zero falls back to null velocity.
   const observedDays = round((latestMs - Date.parse(baseline.fetchedAt)) / (24 * 60 * 60 * 1000));
   const mergedPullRequests = Math.max(0, latest.mergedPullRequestsTotal - baseline.mergedPullRequestsTotal);
   const closedUnmergedPullRequests = Math.max(0, latest.closedUnmergedPullRequestsTotal - baseline.closedUnmergedPullRequestsTotal);
@@ -97,7 +97,7 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   const stalePullRequestRate = latestQueue ? staleRate(latestQueue) : null;
   const baselineStaleRate = baselineQueue ? staleRate(baselineQueue) : null;
   const duplicateTrend = latestQueue && baselineQueue ? latestQueue.collisionClusters - baselineQueue.collisionClusters : null;
-  const reviewVelocityPerDay = round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
+  const reviewVelocityPerDay = computeReviewVelocityPerDay(mergedPullRequests, closedUnmergedPullRequests, observedDays);
   const pullRequestGrowth = latest.openPullRequestsTotal - baseline.openPullRequestsTotal;
   return {
     windowDays,
@@ -113,10 +113,20 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
     stalePullRequestRate,
     stalePullRequestRateDelta: stalePullRequestRate !== null && baselineStaleRate !== null ? round(stalePullRequestRate - baselineStaleRate) : null,
     duplicateTrend,
-    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${reviewVelocityPerDay}/day.`,
+    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${formatReviewVelocityPerDay(reviewVelocityPerDay)}.`,
   };
 }
 
+/** Returns null when observedDays <= 0 (no divide-by-zero / Infinity); otherwise the per-day close+merge rate. */
+export function computeReviewVelocityPerDay(mergedPullRequests: number, closedUnmergedPullRequests: number, observedDays: number): number | null {
+  if (observedDays <= 0) return null;
+  return round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
+}
+
+function formatReviewVelocityPerDay(reviewVelocityPerDay: number | null): string {
+  return reviewVelocityPerDay === null ? "n/a" : `${reviewVelocityPerDay}/day`;
+}
+
 function trendWarnings(windows: QueueTrendWindow[]): string[] {
   const warnings: string[] = [];
   for (const window of windows.filter((entry) => entry.status === "ready")) {
diff --git a/test/unit/queue-trends.test.ts b/test/unit/queue-trends.test.ts
index b6e0c27b03..bb46f999bb 100644
--- a/test/unit/queue-trends.test.ts
+++ b/test/unit/queue-trends.test.ts
@@ -1,7 +1,7 @@
 import { describe, expect, it } from "vitest";
 import { getRepoQueueTrendSnapshot, persistRepoGithubTotalsSnapshot, persistSignalSnapshot, upsertPullRequestFromGitHub, upsertRepositoryFromGitHub } from "../../src/db/repositories";
 import { generateSignalSnapshots } from "../../src/queue/processors";
-import { buildQueueTrendReport, buildUnavailableQueueTrendReport, type QueueTrendReport } from "../../src/services/queue-trends";
+import { buildQueueTrendReport, buildUnavailableQueueTrendReport, computeReviewVelocityPerDay, type QueueTrendReport } from "../../src/services/queue-trends";
 import type { RepoGithubTotalsSnapshotRecord } from "../../src/types";
 import { createTestEnv } from "../helpers/d1";
 
@@ -70,7 +70,9 @@ describe("queue trend windows", () => {
     for (const window of report.windows.filter((entry) => entry.status === "ready")) {
       expect(window.reviewVelocityPerDay).not.toBe(Infinity);
       expect(window.summary).not.toContain("Infinity");
-      expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
+      if (window.reviewVelocityPerDay !== null) {
+        expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
+      }
     }
     expect(report.windows[0]).toMatchObject({
       windowDays: 7,
@@ -92,10 +94,17 @@ describe("queue trend windows", () => {
 
     for (const window of report.windows.filter((entry) => entry.status === "ready")) {
       expect(window.observedDays).toBeGreaterThanOrEqual(window.windowDays);
-      expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
+      if (window.reviewVelocityPerDay !== null) {
+        expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
+      }
     }
   });
 
+  it("returns null review velocity when observedDays is zero", () => {
+    expect(computeReviewVelocityPerDay(7, 3, 0)).toBeNull();
+    expect(computeReviewVelocityPerDay(7, 3, 7)).toBe(1.43);
+  });
+
   it("returns clear unavailable windows when history is missing", () => {
     const report = buildQueueTrendReport({ repoFullName: "owner/repo", totalsSnapshots: [totals(0, { openIssues: 1, openPrs: 1, merged: 0, closed: 0 })] });
     expect(report).toMatchObject({

From ba31b9efed3720acbdd1f0f0966e237f4dc4c625 Mon Sep 17 00:00:00 2001
From: andriypolandki <=>
Date: Mon, 29 Jun 2026 22:39:16 -0700
Subject: [PATCH 8/8] test(queue-trends): lock in finite velocity for ready
 windows

---
 src/services/queue-trends.ts   | 16 +++-------------
 test/unit/queue-trends.test.ts | 15 +++------------
 2 files changed, 6 insertions(+), 25 deletions(-)

diff --git a/src/services/queue-trends.ts b/src/services/queue-trends.ts
index e8c25146e1..41ffb1a7fe 100644
--- a/src/services/queue-trends.ts
+++ b/src/services/queue-trends.ts
@@ -88,7 +88,7 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   const targetMs = latestMs - windowDays * 24 * 60 * 60 * 1000;
   const baseline = [...totals].reverse().find((snapshot) => Date.parse(snapshot.fetchedAt) <= targetMs);
   if (!baseline) return unavailableWindow(windowDays, `Need at least ${windowDays} days of totals history.`);
-  // With a valid baseline, observedDays is normally >= windowDays; zero falls back to null velocity.
+  // Baseline is the newest snapshot at or before (latest - windowDays), so observedDays >= windowDays.
   const observedDays = round((latestMs - Date.parse(baseline.fetchedAt)) / (24 * 60 * 60 * 1000));
   const mergedPullRequests = Math.max(0, latest.mergedPullRequestsTotal - baseline.mergedPullRequestsTotal);
   const closedUnmergedPullRequests = Math.max(0, latest.closedUnmergedPullRequestsTotal - baseline.closedUnmergedPullRequestsTotal);
@@ -97,7 +97,7 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
   const stalePullRequestRate = latestQueue ? staleRate(latestQueue) : null;
   const baselineStaleRate = baselineQueue ? staleRate(baselineQueue) : null;
   const duplicateTrend = latestQueue && baselineQueue ? latestQueue.collisionClusters - baselineQueue.collisionClusters : null;
-  const reviewVelocityPerDay = computeReviewVelocityPerDay(mergedPullRequests, closedUnmergedPullRequests, observedDays);
+  const reviewVelocityPerDay = round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
   const pullRequestGrowth = latest.openPullRequestsTotal - baseline.openPullRequestsTotal;
   return {
     windowDays,
@@ -113,20 +113,10 @@ function buildWindow(windowDays: 7 | 14 | 30, totals: RepoGithubTotalsSnapshotRe
     stalePullRequestRate,
     stalePullRequestRateDelta: stalePullRequestRate !== null && baselineStaleRate !== null ? round(stalePullRequestRate - baselineStaleRate) : null,
     duplicateTrend,
-    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${formatReviewVelocityPerDay(reviewVelocityPerDay)}.`,
+    summary: `${windowDays}d trend: PR queue ${signed(pullRequestGrowth)}, review velocity ${reviewVelocityPerDay}/day.`,
   };
 }
 
-/** Returns null when observedDays <= 0 (no divide-by-zero / Infinity); otherwise the per-day close+merge rate. */
-export function computeReviewVelocityPerDay(mergedPullRequests: number, closedUnmergedPullRequests: number, observedDays: number): number | null {
-  if (observedDays <= 0) return null;
-  return round((mergedPullRequests + closedUnmergedPullRequests) / observedDays);
-}
-
-function formatReviewVelocityPerDay(reviewVelocityPerDay: number | null): string {
-  return reviewVelocityPerDay === null ? "n/a" : `${reviewVelocityPerDay}/day`;
-}
-
 function trendWarnings(windows: QueueTrendWindow[]): string[] {
   const warnings: string[] = [];
   for (const window of windows.filter((entry) => entry.status === "ready")) {
diff --git a/test/unit/queue-trends.test.ts b/test/unit/queue-trends.test.ts
index bb46f999bb..b6e0c27b03 100644
--- a/test/unit/queue-trends.test.ts
+++ b/test/unit/queue-trends.test.ts
@@ -1,7 +1,7 @@
 import { describe, expect, it } from "vitest";
 import { getRepoQueueTrendSnapshot, persistRepoGithubTotalsSnapshot, persistSignalSnapshot, upsertPullRequestFromGitHub, upsertRepositoryFromGitHub } from "../../src/db/repositories";
 import { generateSignalSnapshots } from "../../src/queue/processors";
-import { buildQueueTrendReport, buildUnavailableQueueTrendReport, computeReviewVelocityPerDay, type QueueTrendReport } from "../../src/services/queue-trends";
+import { buildQueueTrendReport, buildUnavailableQueueTrendReport, type QueueTrendReport } from "../../src/services/queue-trends";
 import type { RepoGithubTotalsSnapshotRecord } from "../../src/types";
 import { createTestEnv } from "../helpers/d1";
 
@@ -70,9 +70,7 @@ describe("queue trend windows", () => {
     for (const window of report.windows.filter((entry) => entry.status === "ready")) {
       expect(window.reviewVelocityPerDay).not.toBe(Infinity);
       expect(window.summary).not.toContain("Infinity");
-      if (window.reviewVelocityPerDay !== null) {
-        expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
-      }
+      expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
     }
     expect(report.windows[0]).toMatchObject({
       windowDays: 7,
@@ -94,17 +92,10 @@ describe("queue trend windows", () => {
 
     for (const window of report.windows.filter((entry) => entry.status === "ready")) {
       expect(window.observedDays).toBeGreaterThanOrEqual(window.windowDays);
-      if (window.reviewVelocityPerDay !== null) {
-        expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
-      }
+      expect(Number.isFinite(window.reviewVelocityPerDay)).toBe(true);
     }
   });
 
-  it("returns null review velocity when observedDays is zero", () => {
-    expect(computeReviewVelocityPerDay(7, 3, 0)).toBeNull();
-    expect(computeReviewVelocityPerDay(7, 3, 7)).toBe(1.43);
-  });
-
   it("returns clear unavailable windows when history is missing", () => {
     const report = buildQueueTrendReport({ repoFullName: "owner/repo", totalsSnapshots: [totals(0, { openIssues: 1, openPrs: 1, merged: 0, closed: 0 })] });
     expect(report).toMatchObject({