fix: reconcile duplicate diagnostic stage revisions

Author: richiemcilroy

apps/web/__tests__/unit/desktop-log-upload.test.ts

@@ -137,6 +137,30 @@ describe("desktop diagnostic reconstruction", () => {
 		expect(
 			analysis.operations[0].stages.map((stage) => stage.revision),
 		).toEqual([1, 2, 3]);
+		expect(analysis.operations[0].stages[1]).toEqual({
+			revision: 2,
+			stage: "rendering",
+			elapsedMs: 600,
+			outcome: "in_progress",
+		});
+	});
+
+	it("keeps the newest duplicate stage in either input order", () => {
+		const stale = record({ revision: 2, elapsedMs: 1 });
+		const current = record({ revision: 2, stage: "rendering", elapsedMs: 600 });
+		for (const [snapshot, logged] of [
+			[stale, current],
+			[current, stale],
+		]) {
+			const analysis = analyzeDesktopDiagnostics(logLine(logged), {
+				operations: { records: [snapshot] },
+			});
+			expect(analysis.operations[0]).toMatchObject({
+				stage: "rendering",
+				elapsedMs: 600,
+				stages: [{ revision: 2, stage: "rendering", elapsedMs: 600 }],
+			});
+		}
 	});
 
 	it("links a failed worker to its parent and retains the build and settings", () => {

apps/web/lib/desktop-diagnostic-analysis.ts

@@ -97,8 +97,9 @@ export function analyzeDesktopDiagnostics(log: string, context: unknown) {
 		) {
 			operation.latest = record;
 		}
-		if (!operation.stages.has(record.revision)) {
-			if (operation.stages.size >= 32) {
+		const previousStage = operation.stages.get(record.revision);
+		if (!previousStage || record.elapsedMs > previousStage.elapsedMs) {
+			if (!previousStage && operation.stages.size >= 32) {
 				omittedStages++;
 			} else {
 				operation.stages.set(record.revision, {