Fix image embeds and rkey collisions

- Add image_urls to GetAllUnpublishedItems query
- Add aspectRatio to image embeds (required by Bluesky)
- Add image decoding to get dimensions (width/height)
- Fix rkey collision by using XOR of multiple hash bytes

The rkey collision was caused by using only 2 hash bytes (10 bits)
which had ~0.1% collision rate per pair of items with same timestamp.
Now XORs 8 hash bytes for better entropy distribution.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

crawler.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
@@ -371,7 +372,7 @@ func (c *Crawler) RefreshAllProfiles(publisher *Publisher, feedPassword string)
 func (c *Crawler) GetAllUnpublishedItems(limit int) ([]Item, error) {
 	rows, err := c.db.Query(`
 		SELECT i.id, i.feed_url, i.guid, i.title, i.link, i.description, i.content,
-		       i.author, i.pub_date, i.discovered_at
+		       i.author, i.pub_date, i.discovered_at, i.image_urls
 		FROM items i
 		JOIN feeds f ON i.feed_url = f.url
 		WHERE f.publish_status = 'pass'
@@ -388,11 +389,11 @@ func (c *Crawler) GetAllUnpublishedItems(limit int) ([]Item, error) {
 	var items []Item
 	for rows.Next() {
 		var item Item
-		var guid, title, link, description, content, author *string
+		var guid, title, link, description, content, author, imageURLsJSON *string
 		var pubDate, discoveredAt *time.Time
 
 		err := rows.Scan(&item.ID, &item.FeedURL, &guid, &title, &link, &description,
-			&content, &author, &pubDate, &discoveredAt)
+			&content, &author, &pubDate, &discoveredAt, &imageURLsJSON)
 		if err != nil {
 			continue
 		}
@@ -406,6 +407,11 @@ func (c *Crawler) GetAllUnpublishedItems(limit int) ([]Item, error) {
 		item.PubDate = TimeValue(pubDate)
 		item.DiscoveredAt = TimeValue(discoveredAt)
 
+		// Parse image URLs from JSON array
+		if imageURLsJSON != nil && *imageURLsJSON != "" {
+			json.Unmarshal([]byte(*imageURLsJSON), &item.ImageURLs)
+		}
+
 		items = append(items, item)
 	}
 

publisher.go

@@ -5,6 +5,10 @@ import (
 	"crypto/sha256"
 	"encoding/json"
 	"fmt"
+	"image"
+	_ "image/gif"
+	_ "image/jpeg"
+	_ "image/png"
 	"io"
 	"net/http"
 	"net/url"
@@ -12,6 +16,8 @@ import (
 	"strings"
 	"time"
 	"unicode/utf8"
+
+	_ "golang.org/x/image/webp"
 )
 
 // Publisher handles posting items to AT Protocol PDS
@@ -66,8 +72,14 @@ type BskyExternal struct {
 }
 
 type BskyImage struct {
-	Alt   string   `json:"alt"`
-	Image *BlobRef `json:"image"`
+	Alt         string            `json:"alt"`
+	Image       *BlobRef          `json:"image"`
+	AspectRatio *BskyAspectRatio  `json:"aspectRatio,omitempty"`
+}
+
+type BskyAspectRatio struct {
+	Width  int `json:"width"`
+	Height int `json:"height"`
 }
 
 // NewPublisher creates a new Publisher instance
@@ -216,8 +228,12 @@ func GenerateRkey(guid string, timestamp time.Time) string {
 	micros := uint64(microsInt) & ((1 << 53) - 1)
 
 	// Generate deterministic 10-bit clock ID from GUID hash
+	// Use XOR of multiple hash bytes to reduce collisions
 	hash := sha256.Sum256([]byte(guid))
-	clockID := uint64(hash[0])<<2 | uint64(hash[1])>>6
+	// XOR bytes 0-3 together, then 4-7, combine for more entropy
+	h1 := uint64(hash[0]) ^ uint64(hash[2]) ^ uint64(hash[4]) ^ uint64(hash[6])
+	h2 := uint64(hash[1]) ^ uint64(hash[3]) ^ uint64(hash[5]) ^ uint64(hash[7])
+	clockID := (h1 << 2) | (h2 >> 6)
 	clockID = clockID & ((1 << 10) - 1) // 10 bits = 0-1023
 
 	// Combine: top bit 0, 53 bits timestamp, 10 bits clock ID
@@ -460,12 +476,19 @@ func (p *Publisher) uploadImages(session *PDSSession, imageURLs []string, altTex
 	}
 
 	for i := 0; i < maxImages; i++ {
-		blob := p.fetchAndUploadImage(session, imageURLs[i])
-		if blob != nil {
-			images = append(images, BskyImage{
+		result := p.fetchAndUploadImageWithDimensions(session, imageURLs[i])
+		if result != nil && result.Blob != nil {
+			img := BskyImage{
 				Alt:   altText,
-				Image: blob,
-			})
+				Image: result.Blob,
+			}
+			if result.Width > 0 && result.Height > 0 {
+				img.AspectRatio = &BskyAspectRatio{
+					Width:  result.Width,
+					Height: result.Height,
+				}
+			}
+			images = append(images, img)
 		}
 	}
 
@@ -514,7 +537,22 @@ func (p *Publisher) FetchFavicon(siteURL string) string {
 	return fmt.Sprintf("https://www.google.com/s2/favicons?domain=%s&sz=128", u.Host)
 }
 
+// ImageUploadResult contains the uploaded blob and image dimensions
+type ImageUploadResult struct {
+	Blob   *BlobRef
+	Width  int
+	Height int
+}
+
 func (p *Publisher) fetchAndUploadImage(session *PDSSession, imageURL string) *BlobRef {
+	result := p.fetchAndUploadImageWithDimensions(session, imageURL)
+	if result == nil {
+		return nil
+	}
+	return result.Blob
+}
+
+func (p *Publisher) fetchAndUploadImageWithDimensions(session *PDSSession, imageURL string) *ImageUploadResult {
 	// Fetch the image
 	resp, err := p.httpClient.Get(imageURL)
 	if err != nil {
@@ -552,13 +590,24 @@ func (p *Publisher) fetchAndUploadImage(session *PDSSession, imageURL string) *B
 		return nil
 	}
 
+	// Decode image to get dimensions
+	img, _, err := image.DecodeConfig(bytes.NewReader(data))
+	width, height := 1, 1 // Default if decode fails
+	if err == nil {
+		width, height = img.Width, img.Height
+	}
+
 	// Upload to PDS
 	blob, err := p.UploadBlob(session, data, contentType)
 	if err != nil {
 		return nil
 	}
 
-	return blob
+	return &ImageUploadResult{
+		Blob:   blob,
+		Width:  width,
+		Height: height,
+	}
 }
 
 func truncate(s string, maxLen int) string {