fix: add 429 retry with exponential backoff and increase rate limit delay

- Retry up to 5 times on HTTP 429 with 2s/4s/8s/16s backoff
- Move inter-request delay before each request (was after)
- Increase base delay from 1s to 2s between requests
- Fix: only sleep after first request (skip delay on first call)

1 files changed, 32 insertions, 9 deletions

diff --git a/src/wikiarticle.go b/src/wikiarticle.go
index 61a6084..4ff72b6 100644
--- a/src/wikiarticle.go
+++ b/src/wikiarticle.go
@@ -87,14 +87,16 @@ func (a *App) fetchWikiArticlesData() error {
 
 	// Serial processing with 1 req/s rate limit
 	go func() {
-		for _, item := range entries {
+		for i, item := range entries {
+			if i > 0 {
+				time.Sleep(2 * time.Second)
+			}
 			entry, err := a.queryWikiArticle(item.wikiArticle)
 			if err != nil {
-				log.Printf("wiki error for %s (%s): %v", item.imdbID, item.wikiArticle, err)
+				log.Printf("wiki error for %s/%d (%s): %v", item.imdbID, i, item.wikiArticle, err)
 				continue
 			}
 			ch <- result{id: item.id, entry: entry}
-			time.Sleep(1 * time.Second)
 		}
 		close(ch)
 	}()
@@ -128,17 +130,38 @@ func (a *App) queryWikiArticle(name string) (wikiArticleEntry, error) {
 		"name":     {name},
 	}.Encode()
 
-	resp, err := wikiArticleClient.Get(reqURL)
+	var resp *http.Response
+	var err error
+	for attempt := 0; attempt < 5; attempt++ {
+		if attempt > 0 {
+			backoff := 1 << attempt
+			log.Printf("retry %d/%d for %s after %ds backoff", attempt, 4, name, backoff)
+			time.Sleep(time.Duration(backoff) * time.Second)
+		}
+
+		resp, err = wikiArticleClient.Get(reqURL)
+		if err != nil {
+			continue
+		}
+
+		if resp.StatusCode == http.StatusTooManyRequests {
+			resp.Body.Close()
+			continue
+		}
+
+		if resp.StatusCode != http.StatusOK {
+			body, _ := io.ReadAll(io.LimitReader(resp.Body, 2048))
+			resp.Body.Close()
+			return wikiArticleEntry{}, fmt.Errorf("HTTP %d: %s", resp.StatusCode, body)
+		}
+
+		break
+	}
 	if err != nil {
 		return wikiArticleEntry{}, fmt.Errorf("http get: %w", err)
 	}
 	defer resp.Body.Close()
 
-	if resp.StatusCode != http.StatusOK {
-		body, _ := io.ReadAll(io.LimitReader(resp.Body, 2048))
-		return wikiArticleEntry{}, fmt.Errorf("HTTP %d: %s", resp.StatusCode, body)
-	}
-
 	var articles []map[string]interface{}
 	if err := json.NewDecoder(resp.Body).Decode(&articles); err != nil {
 		return wikiArticleEntry{}, fmt.Errorf("json decode: %w", err)