fix(web): stored pull request details keep only the 20 most recent

apps/web/src/components/pullRequest/pullRequestDetail.logic.test.ts

@@ -1825,9 +1825,37 @@ describe("cached pull request detail", () => {
     return {
       getItem: (key: string) => held.get(key) ?? null,
       setItem: (key: string, value: string) => void held.set(key, value),
+      removeItem: (key: string) => void held.delete(key),
+      size: () => held.size,
     };
   };
 
+  it("keeps only the 20 most recently saved pull requests", () => {
+    const storage = makeStorage();
+    const numbered = (number: number) => ({ ...reference, number });
+    for (let number = 1; number <= 21; number += 1) {
+      writePullRequestDetailSnapshot(storage, "env-1", numbered(number), detail({ number }));
+    }
+    expect(readPullRequestDetailSnapshot(storage, "env-1", numbered(1))).toBeNull();
+    expect(readPullRequestDetailSnapshot(storage, "env-1", numbered(2))?.number).toBe(2);
+    expect(readPullRequestDetailSnapshot(storage, "env-1", numbered(21))?.number).toBe(21);
+    // Twenty snapshots plus the list of their keys.
+    expect(storage.size()).toBe(21);
+  });
+
+  it("saving a pull request again keeps it as the newest without growing the list", () => {
+    const storage = makeStorage();
+    const numbered = (number: number) => ({ ...reference, number });
+    for (let number = 1; number <= 20; number += 1) {
+      writePullRequestDetailSnapshot(storage, "env-1", numbered(number), detail({ number }));
+    }
+    writePullRequestDetailSnapshot(storage, "env-1", numbered(1), detail({ number: 1 }));
+    writePullRequestDetailSnapshot(storage, "env-1", numbered(21), detail({ number: 21 }));
+    expect(readPullRequestDetailSnapshot(storage, "env-1", numbered(1))?.number).toBe(1);
+    expect(readPullRequestDetailSnapshot(storage, "env-1", numbered(2))).toBeNull();
+    expect(storage.size()).toBe(21);
+  });
+
   it("hydrates the last title, author, and counts so a reopen does not ghost the tab", () => {
     const storage = makeStorage();
     writePullRequestDetailSnapshot(storage, "env-1", reference, detail());

apps/web/src/components/pullRequest/pullRequestDetail.logic.ts

@@ -1152,7 +1152,7 @@ export function canDeletePullRequestBranch(
   );
 }
 
-type SnapshotStorage = Pick<Storage, "getItem" | "setItem">;
+type SnapshotStorage = Pick<Storage, "getItem" | "setItem" | "removeItem">;
 
 export function resolvePullRequestReferenceHost(
   reference: PullRequestRef,
@@ -1203,17 +1203,38 @@ export function readPullRequestDetailSnapshot(
   }
 }
 
+// Snapshot keys in the order they were last written, oldest first.
+const PULL_REQUEST_DETAIL_SNAPSHOT_INDEX_KEY = "t3.pullRequests.recentDetails";
+const PULL_REQUEST_DETAIL_SNAPSHOT_LIMIT = 20;
+
+function readPullRequestDetailSnapshotIndex(storage: SnapshotStorage): string[] {
+  try {
+    const keys: unknown = JSON.parse(
+      storage.getItem(PULL_REQUEST_DETAIL_SNAPSHOT_INDEX_KEY) ?? "[]",
+    );
+    return Array.isArray(keys) ? keys.filter((key): key is string => typeof key === "string") : [];
+  } catch {
+    return [];
+  }
+}
+
+// Keeps the snapshots of the 20 most recently saved pull requests and removes older ones.
 export function writePullRequestDetailSnapshot(
   storage: SnapshotStorage | undefined,
   environmentId: string,
   reference: PullRequestDetailSnapshotRef,
   detail: PullRequestDetail,
 ): void {
+  if (!storage) return;
   try {
-    storage?.setItem(
-      pullRequestDetailSnapshotKey(environmentId, reference),
-      JSON.stringify(detail),
-    );
+    const key = pullRequestDetailSnapshotKey(environmentId, reference);
+    const recent = readPullRequestDetailSnapshotIndex(storage).filter((entry) => entry !== key);
+    recent.push(key);
+    for (const evicted of recent.splice(0, recent.length - PULL_REQUEST_DETAIL_SNAPSHOT_LIMIT)) {
+      storage.removeItem(evicted);
+    }
+    storage.setItem(PULL_REQUEST_DETAIL_SNAPSHOT_INDEX_KEY, JSON.stringify(recent));
+    storage.setItem(key, JSON.stringify(detail));
   } catch {}
 }