From 0d27920a784e57717508d24d80eb75c41e1c4b1b Mon Sep 17 00:00:00 2001
From: vince <vince@linux-infra.dimensionlab.net>
Date: Sat, 20 Jun 2026 15:04:51 +0200
Subject: [PATCH] fix(web): preserve coalesced tile error logs

---
 apps/web/src/server/routes/dashboard.test.ts | 56 +++++++++++++++
 apps/web/src/server/routes/dashboard.ts      | 73 +++++++++++++++++---
 2 files changed, 119 insertions(+), 10 deletions(-)

diff --git a/apps/web/src/server/routes/dashboard.test.ts b/apps/web/src/server/routes/dashboard.test.ts
index a143517..d40e263 100644
--- a/apps/web/src/server/routes/dashboard.test.ts
+++ b/apps/web/src/server/routes/dashboard.test.ts
@@ -389,6 +389,62 @@ describe("dashboard API route", () => {
     ]);
   });
 
+  test("logs coalesced metadata when shared tile requests fail", async () => {
+    const cache = createDashboardTileCache();
+    let rejectLoad: ((error: Error) => void) | undefined;
+    const load = vi.fn(() =>
+      new Promise<never>((_resolve, reject) => {
+        rejectLoad = reject;
+      })
+    );
+
+    const first = cache.resolve("tile-a", 30_000, 1_000, load);
+    const second = cache.resolve("tile-a", 30_000, 1_000, load);
+
+    await Promise.resolve();
+    expect(load).toHaveBeenCalledTimes(1);
+
+    rejectLoad?.(new TypeError("upstream failed"));
+    await expect(first).rejects.toThrow("upstream failed");
+    await expect(second).rejects.toMatchObject({
+      cache: "miss",
+      coalesced: true,
+      cause: expect.any(TypeError),
+    });
+  });
+
+  test("logs coalesced metadata for failed tile cache resolution", async () => {
+    const logs: DashboardTileResolutionLogEvent[] = [];
+    const tile = { kind: "service", groupId: "essentials", id: "vaultwarden" } as const;
+
+    await expect(
+      loadDashboardTileResponse(tile, {
+        logTileResolution: (event) => logs.push(event),
+        refreshSeedDocument: true,
+        seedIfEmpty: true,
+        tileCache: {
+          async resolve() {
+            throw {
+              cache: "miss",
+              cause: new TypeError("coalesced cache failed"),
+              coalesced: true,
+            };
+          },
+        },
+      }),
+    ).rejects.toThrow("coalesced cache failed");
+
+    expect(logs).toEqual([
+      expect.objectContaining({
+        cache: "miss",
+        coalesced: true,
+        errorCategory: "TypeError",
+        status: "error",
+        tileKey: dashboardTileCacheKey(tile),
+      }),
+    ]);
+  });
+
   test("logs error categories for failed tile cache resolution", async () => {
     const logs: DashboardTileResolutionLogEvent[] = [];
     const tile = { kind: "service", groupId: "essentials", id: "vaultwarden" } as const;
diff --git a/apps/web/src/server/routes/dashboard.ts b/apps/web/src/server/routes/dashboard.ts
index 9c32d26..42c4088 100644
--- a/apps/web/src/server/routes/dashboard.ts
+++ b/apps/web/src/server/routes/dashboard.ts
@@ -77,11 +77,18 @@ export function createDashboardTileCache(): DashboardTileCache {
 
       const active = inFlight.get(key);
       if (active) {
-        return active.then((response) => ({
-          cache: "miss",
-          coalesced: true,
-          response,
-        }));
+        return active
+          .then((response) => ({
+            cache: "miss" as const,
+            coalesced: true,
+            response,
+          }))
+          .catch((error) => {
+            throw new DashboardTileCacheResolutionError(error, {
+              cache: "miss",
+              coalesced: true,
+            });
+          });
       }
 
       const request = load()
@@ -101,7 +108,7 @@ export function createDashboardTileCache(): DashboardTileCache {
 
       inFlight.set(key, request);
       return request.then((response) => ({
-        cache: "miss",
+        cache: "miss" as const,
         coalesced: false,
         response,
       }));
@@ -216,15 +223,16 @@ export async function loadDashboardTileResponse(
     });
     return result.response;
   } catch (error) {
+    const cacheError = dashboardTileCacheResolutionError(error);
     logDashboardTileResolution(options, {
-      cache: "miss",
-      coalesced: false,
+      cache: cacheError?.cache ?? "miss",
+      coalesced: cacheError?.coalesced ?? false,
       durationMs: elapsedDashboardTileMs(startedAt, options),
-      errorCategory: dashboardTileErrorCategory(error),
+      errorCategory: dashboardTileErrorCategory(cacheError?.cause ?? error),
       status: "error",
       tileKey,
     });
-    throw error;
+    throw cacheError?.cause ?? error;
   }
 }
 
@@ -288,6 +296,51 @@ function dashboardTileErrorCategory(error: unknown): string {
   return "unknown";
 }
 
+class DashboardTileCacheResolutionError extends Error {
+  readonly cache: "hit" | "miss";
+  readonly coalesced: boolean;
+  override readonly cause: unknown;
+
+  constructor(
+    cause: unknown,
+    metadata: Pick<DashboardTileCacheResult, "cache" | "coalesced">,
+  ) {
+    super("Dashboard tile cache resolution failed");
+    this.name = "DashboardTileCacheResolutionError";
+    this.cause = cause;
+    this.cache = metadata.cache;
+    this.coalesced = metadata.coalesced;
+  }
+}
+
+function dashboardTileCacheResolutionError(
+  error: unknown,
+): DashboardTileCacheResolutionFailure | null {
+  if (
+    typeof error === "object" &&
+    error !== null &&
+    "cache" in error &&
+    (error.cache === "hit" || error.cache === "miss") &&
+    "coalesced" in error &&
+    typeof error.coalesced === "boolean" &&
+    "cause" in error
+  ) {
+    return {
+      cache: error.cache,
+      cause: error.cause,
+      coalesced: error.coalesced,
+    };
+  }
+
+  return null;
+}
+
+interface DashboardTileCacheResolutionFailure {
+  cache: "hit" | "miss";
+  cause: unknown;
+  coalesced: boolean;
+}
+
 function dashboardTileTtlMs(
   document: DashboardDocument,
   tile: DashboardTileReference,