diff --git a/backend/internal/http/handler/user_generation.go b/backend/internal/http/handler/user_generation.go
index 542737a..5be054d 100644
--- a/backend/internal/http/handler/user_generation.go
+++ b/backend/internal/http/handler/user_generation.go
@@ -401,7 +401,7 @@ func (h *UserGenerationHandler) catalogEntries(c *gin.Context) ([]gin.H, error)
 			"id":                   "nano-banana-2",
 			"provider":             "runway",
 			"type":                 "image",
-			"ratios":               []string{"16:9", "9:16", "1:1", "4:3", "3:4", "21:9", "3:2", "5:4", "4:5", "2:3"},
+			"ratios":               []string{"1:1", "1:4", "1:8", "2:3", "3:2", "3:4", "4:1", "4:3", "4:5", "5:4", "8:1", "9:16", "16:9", "21:9"},
 			"resolutions":          []string{"1K", "2K", "4K"},
 			"image_to_image":       true,
 			"max_reference_images": 6,
@@ -562,7 +562,7 @@ func (h *UserGenerationHandler) publicModels() ([]gin.H, error) {
 			"id":          "nano-banana-2",
 			"provider":    "runway",
 			"kind":        "image",
-			"ratios":      []string{"16:9", "9:16", "1:1", "4:3", "3:4", "21:9", "3:2", "5:4", "4:5", "2:3"},
+			"ratios":      []string{"1:1", "1:4", "1:8", "2:3", "3:2", "3:4", "4:1", "4:3", "4:5", "5:4", "8:1", "9:16", "16:9", "21:9"},
 			"resolutions": []string{"1K", "2K", "4K"},
 			"description": "Runway Nano Banana 2",
 			"stub":        false,
diff --git a/backend/internal/provider/grok/video.go b/backend/internal/provider/grok/video.go
index edf3069..241f9f8 100644
--- a/backend/internal/provider/grok/video.go
+++ b/backend/internal/provider/grok/video.go
@@ -4,11 +4,13 @@ import (
 	"context"
 	"encoding/base64"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"os"
 	"regexp"
 	"strings"
+	"time"
 
 	http "github.com/bogdanfinn/fhttp"
 	tlsclient "github.com/bogdanfinn/tls-client"
@@ -166,12 +168,31 @@ func (c *Client) GenerateVideo(ctx context.Context, token, prompt, aspectRatio,
 
 // uploadImage uploads one reference frame via /rest/app-chat/upload-file (JSON
 // with base64 content) and returns its asset content URL for imageReferences.
+// Cloudflare's bot score is per-request, so a big base64 upload can hit a
+// "Just a moment…" 403 intermittently while identical requests pass — retry
+// transient failures with backoff instead of failing the whole task.
 func (c *Client) uploadImage(ctx context.Context, client tlsclient.HttpClient, token string, img []byte) (string, error) {
-	res, err := c.postJSON(ctx, client, token, "/rest/app-chat/upload-file", map[string]any{
+	body := map[string]any{
 		"fileName":     "ref.png",
 		"fileMimeType": "image/png",
 		"content":      base64.StdEncoding.EncodeToString(img),
-	})
+	}
+	var res map[string]any
+	var err error
+	backoffs := []time.Duration{0, 2 * time.Second, 5 * time.Second, 10 * time.Second}
+	for _, wait := range backoffs {
+		if wait > 0 {
+			select {
+			case <-ctx.Done():
+				return "", ctx.Err()
+			case <-time.After(wait):
+			}
+		}
+		res, err = c.postJSON(ctx, client, token, "/rest/app-chat/upload-file", body)
+		if err == nil || !errors.Is(err, ErrTemporaryUpstream) {
+			break
+		}
+	}
 	if err != nil {
 		return "", err
 	}
@@ -252,7 +273,9 @@ func (c *Client) doPost(ctx context.Context, client tlsclient.HttpClient, token,
 	defer resp.Body.Close()
 	raw, err := io.ReadAll(resp.Body)
 	if err != nil {
-		return nil, resp.StatusCode, err
+		// Mid-body HTTP/2 stream resets ("stream error: ... INTERNAL_ERROR") are
+		// transient — surface them as retryable.
+		return nil, resp.StatusCode, fmt.Errorf("%w: %v", ErrTemporaryUpstream, err)
 	}
 	return raw, resp.StatusCode, nil
 }
@@ -297,7 +320,29 @@ func (c *Client) OpenAsset(ctx context.Context, token, url string) (io.ReadClose
 	return resp.Body, ct, nil
 }
 
+// download fetches the rendered artifact. The clip is already generated at this
+// point, so a transient failure here (HTTP/2 stream reset, CF hiccup) must not
+// fail the whole task — retry with backoff.
 func (c *Client) download(ctx context.Context, client tlsclient.HttpClient, token, url string) ([]byte, error) {
+	var data []byte
+	var err error
+	for _, wait := range []time.Duration{0, 2 * time.Second, 5 * time.Second, 10 * time.Second} {
+		if wait > 0 {
+			select {
+			case <-ctx.Done():
+				return nil, ctx.Err()
+			case <-time.After(wait):
+			}
+		}
+		data, err = c.downloadOnce(ctx, client, token, url)
+		if err == nil || !errors.Is(err, ErrTemporaryUpstream) {
+			break
+		}
+	}
+	return data, err
+}
+
+func (c *Client) downloadOnce(ctx context.Context, client tlsclient.HttpClient, token, url string) ([]byte, error) {
 	req, err := http.NewRequest(http.MethodGet, url, nil)
 	if err != nil {
 		return nil, err
@@ -318,7 +363,7 @@ func (c *Client) download(ctx context.Context, client tlsclient.HttpClient, toke
 	}
 	data, err := io.ReadAll(resp.Body)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("%w: %v", ErrTemporaryUpstream, err)
 	}
 	if len(data) == 0 {
 		return nil, fmt.Errorf("%w: empty video download", ErrTemporaryUpstream)
diff --git a/backend/internal/service/v1.go b/backend/internal/service/v1.go
index ceb1c93..d315b2b 100644
--- a/backend/internal/service/v1.go
+++ b/backend/internal/service/v1.go
@@ -995,6 +995,10 @@ func (s *V1Service) prepareImage(ctx context.Context, principal *APIPrincipal, i
 	// an explicit resolution; the OpenAI /v1 path derives it from size. There is no
 	// `quality` param — size is the single source of truth for resolution.
 	aspectRatio, resolution := parseImageSize(in.Size, in.AspectRatio, in.Resolution)
+	// Snap to the nearest ratio the model actually supports — a `size`-derived
+	// ratio (e.g. 1:3) must never be passed through to an upstream that rejects
+	// it (Runway 400s on ratios outside its list).
+	aspectRatio = snapRatio(aspectRatio, repo.JSONStrings(modelItem.Ratios))
 	// parseImageSize defaults a blank resolution to "2K" (OpenAI-size parity).
 	// For a model that doesn't price that tier — e.g. gpt-image-2 is 1K-only —
 	// fall back to its first supported tier so a missing/stale resolution from
@@ -2639,19 +2643,54 @@ func parseImageSize(size, aspectRatio, resolution string) (string, string) {
 	return ar, rs
 }
 
+// snapRatio returns the entry in supported closest in value to ar ("W:H").
+// ar is returned as-is when it's already supported, unparsable, or the model
+// has no ratio list.
+func snapRatio(ar string, supported []string) string {
+	parse := func(s string) (float64, bool) {
+		var w, h int
+		if _, err := fmt.Sscanf(strings.TrimSpace(s), "%d:%d", &w, &h); err != nil || w <= 0 || h <= 0 {
+			return 0, false
+		}
+		return float64(w) / float64(h), true
+	}
+	v, ok := parse(ar)
+	if !ok || len(supported) == 0 {
+		return ar
+	}
+	best, bestDelta := "", 0.0
+	for _, s := range supported {
+		if strings.TrimSpace(strings.ReplaceAll(s, "x", ":")) == ar {
+			return ar
+		}
+		sv, sok := parse(strings.ReplaceAll(s, "x", ":"))
+		if !sok {
+			continue
+		}
+		if d := absFloat(v - sv); best == "" || d < bestDelta {
+			best, bestDelta = strings.TrimSpace(strings.ReplaceAll(s, "x", ":")), d
+		}
+	}
+	if best == "" {
+		return ar
+	}
+	return best
+}
+
 func guessRatio(w, h int) string {
 	type candidate struct {
 		W int
 		H int
 	}
-	// The 13 ratios actually used across our models. Must stay in sync with the
+	// The 17 ratios actually used across our models. Must stay in sync with the
 	// custom-model picker (CustomModelModal RATIO_OPTS) and the docs 对照表, so a
 	// /v1 `size` maps to exactly one of them. 9:21 is intentionally absent —
-	// no image provider accepts it (Runway 400s on it).
+	// no image provider accepts it (Runway 400s on it). snapRatio then clamps
+	// the guess to the target model's own supported list.
 	candidates := []candidate{
 		{1, 1},
-		{5, 4}, {4, 3}, {3, 2}, {16, 9}, {2, 1}, {21, 9}, {3, 1}, // 横
-		{4, 5}, {3, 4}, {2, 3}, {9, 16}, {1, 3}, // 竖
+		{5, 4}, {4, 3}, {3, 2}, {16, 9}, {2, 1}, {21, 9}, {3, 1}, {4, 1}, {8, 1}, // 横
+		{4, 5}, {3, 4}, {2, 3}, {9, 16}, {1, 3}, {1, 4}, {1, 8}, // 竖
 	}
 	best := candidates[0]
 	bestDelta := absFloat(float64(w)/float64(h) - float64(best.W)/float64(best.H))
diff --git a/frontend/src/components/CustomModelModal.vue b/frontend/src/components/CustomModelModal.vue
index 3f17a0e..def3c6b 100644
--- a/frontend/src/components/CustomModelModal.vue
+++ b/frontend/src/components/CustomModelModal.vue
@@ -6,9 +6,9 @@ import SelectMenu from './SelectMenu.vue'
 
 const emit = defineEmits(['close', 'saved'])
 
-// 13 ratios — the union of what our models actually support; kept in sync with
+// 17 ratios — the union of what our models actually support; kept in sync with
 // the backend guessRatio() and the docs 对照表. 9:21 removed (no image provider accepts it).
-const RATIO_OPTS = ['1:1', '5:4', '4:3', '3:2', '16:9', '2:1', '21:9', '3:1', '4:5', '3:4', '2:3', '9:16', '1:3']
+const RATIO_OPTS = ['1:1', '5:4', '4:3', '3:2', '16:9', '2:1', '21:9', '3:1', '4:1', '8:1', '4:5', '3:4', '2:3', '9:16', '1:3', '1:4', '1:8']
 const IMG_RES = ['1K', '2K', '4K']
 const VID_RES = ['720p', '1080p', '2K', '4K']
 const ALL_RES = ['1K', '2K', '4K', '720p', '1080p']
diff --git a/frontend/src/views/DocsView.vue b/frontend/src/views/DocsView.vue
index 70139d5..3de8c65 100644
--- a/frontend/src/views/DocsView.vue
+++ b/frontend/src/views/DocsView.vue
@@ -70,11 +70,15 @@ const sizeTable = [
   { ratio: '2:1 · 横',   k1: '1440x720',  k2: '2880x1440', k4: '4096x2048' },
   { ratio: '21:9 · 超宽', k1: '1680x720',  k2: '2520x1080', k4: '5040x2160' },
   { ratio: '3:1 · 超宽',  k1: '1536x512',  k2: '2304x768',  k4: '3840x1280' },
+  { ratio: '4:1 · 超宽',  k1: '1728x432',  k2: '2880x720',  k4: '4096x1024' },
+  { ratio: '8:1 · 超宽',  k1: '1728x216',  k2: '2880x360',  k4: '4096x512' },
   { ratio: '4:5 · 竖',   k1: '1024x1280', k2: '2048x2560', k4: '3072x3840' },
   { ratio: '3:4 · 竖',   k1: '768x1024',  k2: '1536x2048', k4: '3072x4096' },
   { ratio: '2:3 · 竖',   k1: '800x1200',  k2: '1600x2400', k4: '2400x3600' },
   { ratio: '9:16 · 竖',  k1: '720x1280',  k2: '1152x2048', k4: '2304x4096' },
   { ratio: '1:3 · 竖',   k1: '512x1536',  k2: '768x2304',  k4: '1280x3840' },
+  { ratio: '1:4 · 竖',   k1: '432x1728',  k2: '720x2880',  k4: '1024x4096' },
+  { ratio: '1:8 · 竖',   k1: '216x1728',  k2: '360x2880',  k4: '512x4096' },
 ]
 
 // ---- 视频 size → 比例 × 分辨率(720p / 1080p)----