Handle Strava rate limiting with abort, retry time and daily usage display

Strava sync for 167 rides exceeds the 100/15-min read limit (2 calls per ride).
Previously a 429 was treated as a skipped ride, so every remaining ride also
failed silently. Now GetJSON returns a typed RateLimitError with RetryAfter
computed from Retry-After/Date and X-RateLimit headers (15-min window resets
at :00/:15/:30/:45, daily at midnight UTC) and tracks Read/Overall usage.
syncRides aborts on 429 with partial progress instead of skipping, and
handleSync emits an SSE error with retry time, daily usage vs limit and
structured rateLimit snapshot; progress and complete events also carry the
snapshot for the UI to display. Frontend shows Read daily/15-min usage in
progress details and on completion.

1 files changed, 19 insertions, 3 deletions

diff --git a/web/frontend/sync.ts b/web/frontend/sync.ts
index 000dcfc..f58d224 100644
--- a/web/frontend/sync.ts
+++ b/web/frontend/sync.ts
@@ -1,4 +1,4 @@
-import type { SyncErrorEvent, SyncProgress } from "./types.js";
+import type { RateLimitSnapshot, SyncErrorEvent, SyncProgress } from "./types.js";
 import { requireElement } from "./dom.js";
 
 const isSyncProgress = (data: SyncProgress | SyncErrorEvent): data is SyncProgress => "total" in data;
@@ -18,12 +18,28 @@ export const mountSync = (): void => {
     error.textContent = message;
     error.hidden = false;
   };
+  const getRateLimit = (data: SyncProgress | SyncErrorEvent): RateLimitSnapshot | undefined => {
+    if ("rateLimit" in data && data.rateLimit) return data.rateLimit;
+    if ("progress" in data && data.progress?.rateLimit) return data.progress.rateLimit;
+    return undefined;
+  };
+
+  const formatRateLimit = (data: SyncProgress | SyncErrorEvent): string => {
+    const rl = getRateLimit(data);
+    if (!rl) return "";
+    const parts: string[] = [];
+    if (rl.read?.limitDaily) parts.push(`Read ${rl.read.usageDaily}/${rl.read.limitDaily} daily`);
+    if (rl.read?.limit15) parts.push(`${rl.read.usage15}/${rl.read.limit15} (15-min)`);
+    if (parts.length === 0 && rl.overall?.limitDaily) parts.push(`Overall ${rl.overall.usageDaily}/${rl.overall.limitDaily} daily`);
+    return parts.length ? ` · ${parts.join(" · ")}` : "";
+  };
+
   const updateProgress = (progress: SyncProgress): void => {
     progressPanel.hidden = false;
     progressBar.max = Math.max(progress.total, 1);
     progressBar.value = progress.completed;
     progressCount.textContent = `${progress.completed} / ${progress.total}`;
-    progressDetails.textContent = `${progress.imported} imported · ${progress.skipped} skipped`;
+    progressDetails.textContent = `${progress.imported} imported · ${progress.skipped} skipped${formatRateLimit(progress)}`;
   };
   const handleEvent = (eventName: string, data: SyncProgress | SyncErrorEvent): boolean => {
     if (eventName === "progress") {
@@ -34,7 +50,7 @@ export const mountSync = (): void => {
     if (eventName === "complete") {
       if (!isSyncProgress(data)) throw new Error("Invalid Strava sync completion event");
       updateProgress(data);
-      notice.textContent = `Sync complete: ${data.imported} imported, ${data.skipped} skipped.`;
+      notice.textContent = `Sync complete: ${data.imported} imported, ${data.skipped} skipped.${formatRateLimit(data)}`;
       notice.hidden = false;
       return true;
     }