fix(app): make session navigation stable and fast (#33569)

Co-authored-by: Brendan Allan <git@brendonovich.dev>
2026-06-24 07:48:54 +00:00
parent abcfeb380b
commit a4551a94b4
29 changed files with 1028 additions and 202 deletions
@@ -0,0 +1,34 @@
+import { expect, test } from "bun:test"
+import { summarizeNavigationMilestones } from "../timeline/navigation-milestones"
+
+test("reports first and stable paint for each navigation milestone", () => {
+  expect(
+    summarizeNavigationMilestones([
+      { observedAtMs: 16, milestones: { content: false, tab: false } },
+      { observedAtMs: 32, milestones: { content: true, tab: false } },
+      { observedAtMs: 48, milestones: { content: true, tab: true } },
+      { observedAtMs: 64, milestones: { content: true, tab: true } },
+      { observedAtMs: 80, milestones: { content: true, tab: true } },
+    ]),
+  ).toEqual({
+    samples: 5,
+    milestones: {
+      content: { firstObservedMs: 32, stableObservedMs: 64 },
+      tab: { firstObservedMs: 48, stableObservedMs: 80 },
+    },
+    all: { firstObservedMs: 48, stableObservedMs: 80 },
+  })
+})
+
+test("reports missing stability when a milestone appears in the final samples", () => {
+  expect(
+    summarizeNavigationMilestones([
+      { observedAtMs: 16, milestones: { content: false } },
+      { observedAtMs: 32, milestones: { content: true } },
+    ]),
+  ).toEqual({
+    samples: 2,
+    milestones: { content: { firstObservedMs: 32, stableObservedMs: null } },
+    all: { firstObservedMs: 32, stableObservedMs: null },
+  })
+})