fix: address code review issues in album and generation skeleton packages

- Add ErrAnchorRequired sentinel to pkg/album — replaces fragile string equality check
  used for 422 detection; callers now use errors.Is()
- Extract parseShotIndex() helper in album handler — replaces fmt.Sscanf which silently
  accepted partial parses like "12abc"; strconv.Atoi requires the full string to be numeric
- Restructure caption saves in album/handler — captions now written outside the
  len(img.Data) > 0 gate, so URL-only providers (no bytes returned) still get captions
- Add storage.FetchURL() shared utility — removes fetchBytes/downloadURL duplication
  across album and generation packages; callers control timeout via their http.Client
- Add video captions to VideoHandler — same caption sidecar pattern applied to videos
- Add persona generation event types to realtime package — persona_spec_*, persona_image_*,
  persona_video_* events added to EventType union and usePersonaGeneration hook exported

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/adapter/templates/templates/components/service/internal/api/handlers/album.go.tmpl

@@ -1,8 +1,9 @@
 package handlers
 
 import (
-	"fmt"
+	"errors"
 	"net/http"
+	"strconv"
 
 	"github.com/go-chi/chi/v5"
 
@@ -207,7 +208,7 @@ func (h *Album) GenerateAllShots(w http.ResponseWriter, r *http.Request) error {
 
 	jobIDs, err := h.albums.GenerateAllShots(r.Context(), id, user.ID)
 	if err != nil {
-		if err.Error() == "anchor must be generated before shots" {
+		if errors.Is(err, album.ErrAnchorRequired) {
 			return httperror.UnprocessableEntity("anchor must be generated before shots")
 		}
 		return httperror.NotFound("album not found")
@@ -234,16 +235,14 @@ func (h *Album) GenerateShot(w http.ResponseWriter, r *http.Request) error {
 		return httperror.BadRequest("album ID is required")
 	}
 
-	shotIndex := 0
-	if idx := chi.URLParam(r, "index"); idx != "" {
-		if _, err := fmt.Sscanf(idx, "%d", &shotIndex); err != nil {
-			return httperror.BadRequest("invalid shot index")
-		}
+	shotIndex, err := parseShotIndex(chi.URLParam(r, "index"))
+	if err != nil {
+		return httperror.BadRequest("shot index must be a non-negative integer")
 	}
 
 	jobID, err := h.albums.GenerateShot(r.Context(), id, user.ID, shotIndex)
 	if err != nil {
-		if err.Error() == "anchor must be generated before shots" {
+		if errors.Is(err, album.ErrAnchorRequired) {
 			return httperror.UnprocessableEntity("anchor must be generated before shots")
 		}
 		return httperror.NotFound("album or shot not found")
@@ -265,11 +264,9 @@ func (h *Album) ResetShot(w http.ResponseWriter, r *http.Request) error {
 		return httperror.BadRequest("album ID is required")
 	}
 
-	shotIndex := 0
-	if idx := chi.URLParam(r, "index"); idx != "" {
-		if _, err := fmt.Sscanf(idx, "%d", &shotIndex); err != nil {
-			return httperror.BadRequest("invalid shot index")
-		}
+	shotIndex, err := parseShotIndex(chi.URLParam(r, "index"))
+	if err != nil {
+		return httperror.BadRequest("shot index must be a non-negative integer")
 	}
 
 	if err := h.albums.ResetShot(r.Context(), id, user.ID, shotIndex); err != nil {
@@ -279,3 +276,16 @@ func (h *Album) ResetShot(w http.ResponseWriter, r *http.Request) error {
 	httpresponse.NoContent(w)
 	return nil
 }
+
+// parseShotIndex parses and validates the shot index URL parameter.
+// Returns an error if the value is missing, non-numeric, or negative.
+func parseShotIndex(idx string) (int, error) {
+	if idx == "" {
+		return 0, errors.New("missing shot index")
+	}
+	n, err := strconv.Atoi(idx)
+	if err != nil || n < 0 {
+		return 0, errors.New("shot index must be a non-negative integer")
+	}
+	return n, nil
+}

internal/adapter/templates/templates/components/service/internal/service/album.go.tmpl

@@ -122,7 +122,7 @@ func (s *AlbumService) GenerateAllShots(ctx context.Context, id album.AlbumID, u
 		return nil, fmt.Errorf("album not found: %w", err)
 	}
 	if a.AnchorURL == "" {
-		return nil, fmt.Errorf("anchor must be generated before shots")
+		return nil, album.ErrAnchorRequired
 	}
 
 	var jobIDs []string

internal/adapter/templates/templates/skeleton/packages/realtime/src/index.ts

@@ -4,3 +4,4 @@ export { useMediaGeneration, type GenerationStatus, type UseMediaGenerationConfi
 export { useChat, type UseChatConfig, type UseChatResult, type ChatMessage } from './useChat';
 export { useMediaUpload, type UploadProgress, type UploadResult, type UseMediaUploadConfig, type UseMediaUploadResult } from './useMediaUpload';
 export { useAlbumGeneration, type Album, type Shot, type ShotStatus, type UseAlbumGenerationConfig, type UseAlbumGenerationResult } from './useAlbumGeneration';
+export { usePersonaGeneration, type PersonaGenerationState, type UsePersonaGenerationConfig, type UsePersonaGenerationResult } from './usePersonaGeneration';

internal/adapter/templates/templates/skeleton/packages/realtime/src/types.ts

@@ -22,7 +22,17 @@ export type EventType =
   | 'album_anchor_failed'
   | 'album_shot_generating'
   | 'album_shot_complete'
-  | 'album_shot_failed';
+  | 'album_shot_failed'
+  // Persona generation events (pkg/personagen)
+  | 'persona_spec_started'
+  | 'persona_spec_complete'
+  | 'persona_image_started'
+  | 'persona_image_progress'
+  | 'persona_image_complete'
+  | 'persona_video_started'
+  | 'persona_video_complete'
+  | 'persona_video_failed'
+  | 'persona_failed';
 
 /**
  * Chat message data payload.

internal/adapter/templates/templates/skeleton/pkg/album/handler.go.tmpl

@@ -3,7 +3,6 @@ package album
 import (
 	"context"
 	"fmt"
-	"io"
 	"log/slog"
 	"net/http"
 	"time"
@@ -76,13 +75,19 @@ func AnchorHandler(mg *mediagen.Manager, store storage.Store, pub realtime.Event
 
 		// Persist anchor to storage.
 		anchorURL := img.URL
-		if store != nil && len(img.Data) > 0 {
-			storagePath := fmt.Sprintf("albums/%s/%s/anchor.png", userID, albumID)
-			url, uploadErr := store.Upload(ctx, storagePath, img.Data, "image/png")
-			if uploadErr != nil {
-				logger.Warn("failed to persist anchor to storage, using inline URL", "error", uploadErr, "job_id", job.ID)
-			} else {
-				anchorURL = url
+		if store != nil {
+			if len(img.Data) > 0 {
+				storagePath := fmt.Sprintf("albums/%s/%s/anchor.png", userID, albumID)
+				url, uploadErr := store.Upload(ctx, storagePath, img.Data, "image/png")
+				if uploadErr != nil {
+					logger.Warn("failed to persist anchor to storage, using inline URL", "error", uploadErr, "job_id", job.ID)
+				} else {
+					anchorURL = url
+				}
+			}
+			// Save caption alongside the image regardless of whether bytes were uploaded.
+			// This ensures we always record what generated the image (URL-only providers included).
+			if anchorURL != "" {
 				captionPath := fmt.Sprintf("albums/%s/%s/anchor.caption", userID, albumID)
 				if _, captionErr := store.Upload(ctx, captionPath, []byte(subjectDesc), "text/plain"); captionErr != nil {
 					logger.Warn("failed to persist anchor caption", "error", captionErr, "job_id", job.ID)
@@ -150,10 +155,11 @@ func ShotHandler(mg *mediagen.Manager, store storage.Store, pub realtime.EventPu
 		})
 
 		// Fetch anchor image bytes from storage.
+		const anchorMaxBytes = 20 << 20 // 20 MB — anchor images should be small PNGs
 		var anchorBytes []byte
 		var anchorMime string
 		if anchorURL != "" {
-			data, err := fetchBytes(ctx, anchorURL)
+			data, err := storage.FetchURL(ctx, httpClient, anchorURL, anchorMaxBytes)
 			if err != nil {
 				logger.Warn("failed to fetch anchor image, proceeding without reference",
 					"error", err, "job_id", job.ID, "anchor_url", anchorURL)
@@ -209,14 +215,19 @@ func ShotHandler(mg *mediagen.Manager, store storage.Store, pub realtime.EventPu
 
 		// Persist shot image to storage.
 		imageURL := img.URL
-		if store != nil && len(img.Data) > 0 {
-			storagePath := fmt.Sprintf("albums/%s/%s/shots/%d.png", userID, albumID, shotIndex)
-			url, uploadErr := store.Upload(ctx, storagePath, img.Data, "image/png")
-			if uploadErr != nil {
-				logger.Warn("failed to persist shot to storage, using inline URL",
-					"error", uploadErr, "job_id", job.ID)
-			} else {
-				imageURL = url
+		if store != nil {
+			if len(img.Data) > 0 {
+				storagePath := fmt.Sprintf("albums/%s/%s/shots/%d.png", userID, albumID, shotIndex)
+				url, uploadErr := store.Upload(ctx, storagePath, img.Data, "image/png")
+				if uploadErr != nil {
+					logger.Warn("failed to persist shot to storage, using inline URL",
+						"error", uploadErr, "job_id", job.ID)
+				} else {
+					imageURL = url
+				}
+			}
+			// Save caption alongside the image regardless of whether bytes were uploaded.
+			if imageURL != "" {
 				captionPath := fmt.Sprintf("albums/%s/%s/shots/%d.caption", userID, albumID, shotIndex)
 				if _, captionErr := store.Upload(ctx, captionPath, []byte(prompt), "text/plain"); captionErr != nil {
 					logger.Warn("failed to persist shot caption", "error", captionErr, "job_id", job.ID)
@@ -249,25 +260,3 @@ func ShotHandler(mg *mediagen.Manager, store storage.Store, pub realtime.EventPu
 	}
 }
 
-// fetchBytes downloads raw bytes from a URL.
-// Used to load anchor images at shot-generation time.
-func fetchBytes(ctx context.Context, url string) ([]byte, error) {
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
-	if err != nil {
-		return nil, fmt.Errorf("create request: %w", err)
-	}
-	resp, err := httpClient.Do(req)
-	if err != nil {
-		return nil, fmt.Errorf("fetch: %w", err)
-	}
-	defer resp.Body.Close()
-	if resp.StatusCode != http.StatusOK {
-		return nil, fmt.Errorf("fetch: HTTP %d", resp.StatusCode)
-	}
-	const maxSize = 20 << 20 // 20 MB limit for anchor images
-	data, err := io.ReadAll(io.LimitReader(resp.Body, maxSize))
-	if err != nil {
-		return nil, fmt.Errorf("read: %w", err)
-	}
-	return data, nil
-}

internal/adapter/templates/templates/skeleton/pkg/album/types.go.tmpl

@@ -13,9 +13,14 @@ package album
 
 import (
 	"context"
+	"errors"
 	"time"
 )
 
+// ErrAnchorRequired is returned when shot generation is attempted before the anchor image exists.
+// Handlers should map this to HTTP 422 Unprocessable Entity.
+var ErrAnchorRequired = errors.New("anchor must be generated before shots")
+
 // AlbumID is the unique identifier for an album.
 type AlbumID string
 

internal/adapter/templates/templates/skeleton/pkg/generation/handlers.go.tmpl

@@ -6,7 +6,6 @@ import (
 	"context"
 	"encoding/base64"
 	"fmt"
-	"io"
 	"log/slog"
 	"net/http"
 	"time"
@@ -179,6 +178,7 @@ func VideoHandler(mg *mediagen.Manager, store storage.Store, pub realtime.EventP
 
 		// Build videos array matching frontend VideoResult shape:
 		// { videos: [{ data, isUrl, mimeType }], provider, latencyMs }
+		const videoMaxBytes = 500 << 20 // 500 MB — videos can be large
 		videos := make([]map[string]any, 0, len(resp.Videos))
 		for i, vid := range resp.Videos {
 			videoURL := vid.URL
@@ -193,7 +193,7 @@ func VideoHandler(mg *mediagen.Manager, store storage.Store, pub realtime.EventP
 				if len(vid.Data) > 0 {
 					videoData = vid.Data
 				} else if vid.URL != "" {
-					downloaded, downloadErr := downloadURL(ctx, vid.URL)
+					downloaded, downloadErr := storage.FetchURL(ctx, httpClient, vid.URL, videoMaxBytes)
 					if downloadErr != nil {
 						logger.Warn("failed to download video from provider", "error", downloadErr, "job_id", job.ID)
 					} else {
@@ -209,6 +209,14 @@ func VideoHandler(mg *mediagen.Manager, store storage.Store, pub realtime.EventP
 						videoURL = persistedURL
 					}
 				}
+
+				// Save caption alongside the video regardless of where it's stored.
+				if videoURL != "" && prompt != "" {
+					captionPath := fmt.Sprintf("media/%s/videos/%s_%d.caption", userID, job.ID, i)
+					if _, captionErr := store.Upload(ctx, captionPath, []byte(prompt), "text/plain"); captionErr != nil {
+						logger.Warn("failed to persist video caption", "error", captionErr, "job_id", job.ID)
+					}
+				}
 			}
 
 			videos = append(videos, map[string]any{
@@ -339,26 +347,3 @@ func ChatResponseHandler(tg *textgen.Manager, pub realtime.EventPublisher, logge
 	}
 }
 
-// downloadURL fetches content from a URL and returns the bytes.
-// Used to download provider-hosted videos before persisting to storage.
-func downloadURL(ctx context.Context, url string) ([]byte, error) {
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
-	if err != nil {
-		return nil, fmt.Errorf("create request: %w", err)
-	}
-	resp, err := httpClient.Do(req)
-	if err != nil {
-		return nil, fmt.Errorf("download: %w", err)
-	}
-	defer resp.Body.Close()
-	if resp.StatusCode != http.StatusOK {
-		return nil, fmt.Errorf("download: status %d", resp.StatusCode)
-	}
-	// Limit body to 500MB to prevent OOM from unexpected large responses.
-	const maxBodySize = 500 << 20
-	data, err := io.ReadAll(io.LimitReader(resp.Body, maxBodySize))
-	if err != nil {
-		return nil, fmt.Errorf("read body: %w", err)
-	}
-	return data, nil
-}

internal/adapter/templates/templates/skeleton/pkg/storage/fetch.go.tmpl

@@ -0,0 +1,31 @@
+package storage
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+)
+
+// FetchURL downloads content from a URL using the provided HTTP client.
+// maxBytes caps the download to prevent OOM from unexpectedly large responses.
+// Callers control the timeout via the http.Client they pass in.
+func FetchURL(ctx context.Context, client *http.Client, url string, maxBytes int64) ([]byte, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("create request: %w", err)
+	}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("fetch: %w", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("fetch: HTTP %d", resp.StatusCode)
+	}
+	data, err := io.ReadAll(io.LimitReader(resp.Body, maxBytes))
+	if err != nil {
+		return nil, fmt.Errorf("read: %w", err)
+	}
+	return data, nil
+}