FIX: Missing CORS

CLAUDE.md

@@ -372,7 +372,14 @@ on boot if any required var is empty.
 - **S3 + CloudFront**: `encoded-bucket` holds finished transcoded output,
   served publicly via CloudFront using Origin Access Control (OAC) — the
   bucket itself blocks all public access; only CloudFront's OAC principal
-  can read it.
+  can read it. The distribution carries a **response headers policy** adding
+  permissive CORS headers (`*`, `GET`/`HEAD`/`OPTIONS`), and `OPTIONS` is in
+  the behaviour's allowed/cached methods so CloudFront answers preflights
+  itself: HLS is fetched by JavaScript, so a playlist or segment served
+  without `Access-Control-Allow-Origin` is discarded by the browser. The
+  bucket also carries its own equivalent CORS rule, which is what the
+  LocalStack stack relies on — there is no CloudFront there and
+  `PLAYBACK_BASE_URL` points the player straight at S3.
 - **S3 raw uploads**: `raw-uploads-bucket` is a separate, private bucket for
   pre-transcode uploads — deliberately kept apart from `encoded-bucket` so
   raw source video is never reachable through the public CDN. CORS is

infrastructure/main.go

@@ -426,6 +426,42 @@ func main() {
 				return err
 			}
 
+			// HLS is played by JavaScript (hls.js fetches the .m3u8 playlist
+			// and every .ts/.m4s segment with XHR), so the CDN has to answer
+			// with CORS headers or the browser drops the response — the
+			// "CORS Missing Allow Origin" failure. The S3 origin sends none of
+			// its own, so CloudFront adds them here, at the edge, for cached
+			// and uncached responses alike.
+			corsHeaders, err := cloudfront.NewResponseHeadersPolicy(ctx, "encoded-bucket-cors-headers", &cloudfront.ResponseHeadersPolicyArgs{
+				Comment: pulumi.String("CORS headers so browsers can fetch HLS playlists and segments"),
+				CorsConfig: &cloudfront.ResponseHeadersPolicyCorsConfigArgs{
+					AccessControlAllowCredentials: pulumi.Bool(false),
+					AccessControlAllowHeaders: &cloudfront.ResponseHeadersPolicyCorsConfigAccessControlAllowHeadersArgs{
+						Items: pulumi.ToStringArray([]string{"*"}),
+					},
+					AccessControlAllowMethods: &cloudfront.ResponseHeadersPolicyCorsConfigAccessControlAllowMethodsArgs{
+						Items: pulumi.ToStringArray([]string{"GET", "HEAD", "OPTIONS"}),
+					},
+					// Playback is public and unauthenticated, so any origin may
+					// read it. A wildcard also keeps Origin out of the cache
+					// key: with a fixed list CloudFront would have to vary the
+					// cached response on the request's Origin header.
+					AccessControlAllowOrigins: &cloudfront.ResponseHeadersPolicyCorsConfigAccessControlAllowOriginsArgs{
+						Items: pulumi.ToStringArray([]string{"*"}),
+					},
+					// Content-Range/Content-Length are what a player reads back
+					// when it seeks with a Range request.
+					AccessControlExposeHeaders: &cloudfront.ResponseHeadersPolicyCorsConfigAccessControlExposeHeadersArgs{
+						Items: pulumi.ToStringArray([]string{"Content-Length", "Content-Range", "Date", "ETag"}),
+					},
+					AccessControlMaxAgeSec: pulumi.Int(3000),
+					OriginOverride:         pulumi.Bool(true),
+				},
+			})
+			if err != nil {
+				return err
+			}
+
 			distribution, err = cloudfront.NewDistribution(ctx, "encoded-bucket-cdn", &cloudfront.DistributionArgs{
 				Enabled: pulumi.Bool(true),
 				Comment: pulumi.String("Edge caching for encoded-bucket assets"),
@@ -442,10 +478,14 @@ func main() {
 				DefaultCacheBehavior: &cloudfront.DistributionDefaultCacheBehaviorArgs{
 					TargetOriginId:       pulumi.String(originId),
 					ViewerProtocolPolicy: pulumi.String("redirect-to-https"),
-					AllowedMethods:       pulumi.ToStringArray([]string{"GET", "HEAD"}),
-					CachedMethods:        pulumi.ToStringArray([]string{"GET", "HEAD"}),
+					// OPTIONS is listed so CloudFront answers CORS preflights
+					// itself from the response headers policy below; without it
+					// a preflight is rejected with 403 before the policy runs.
+					AllowedMethods:          pulumi.ToStringArray([]string{"GET", "HEAD", "OPTIONS"}),
+					CachedMethods:           pulumi.ToStringArray([]string{"GET", "HEAD", "OPTIONS"}),
 					Compress:                pulumi.Bool(true),
 					CachePolicyId:           pulumi.String(cachingOptimizedPolicyId),
+					ResponseHeadersPolicyId: corsHeaders.ID(),
 				},
 				Restrictions: &cloudfront.DistributionRestrictionsArgs{
 					GeoRestriction: &cloudfront.DistributionRestrictionsGeoRestrictionArgs{
@@ -1274,6 +1314,27 @@ func main() {
 			corsOrigins = pulumi.StringArray{pulumi.Sprintf("http://%s", cmsAlb.DnsName)}
 		}
 
+		// The encoded bucket needs its own CORS rule for the LocalStack stack,
+		// where there is no CloudFront in front of it and PLAYBACK_BASE_URL
+		// points the player straight at S3. Behind CloudFront the response
+		// headers policy already covers playback, but the rule is harmless
+		// there and keeps a direct-to-bucket player working either way.
+		_, err = s3.NewBucketCorsConfigurationV2(ctx, "encoded-bucket-cors", &s3.BucketCorsConfigurationV2Args{
+			Bucket: bucket.ID(),
+			CorsRules: s3.BucketCorsConfigurationV2CorsRuleArray{
+				&s3.BucketCorsConfigurationV2CorsRuleArgs{
+					AllowedMethods: pulumi.ToStringArray([]string{"GET", "HEAD"}),
+					AllowedOrigins: pulumi.ToStringArray([]string{"*"}),
+					AllowedHeaders: pulumi.ToStringArray([]string{"*"}),
+					ExposeHeaders:  pulumi.ToStringArray([]string{"Content-Length", "Content-Range", "Date", "ETag"}),
+					MaxAgeSeconds:  pulumi.Int(3000),
+				},
+			},
+		})
+		if err != nil {
+			return err
+		}
+
 		_, err = s3.NewBucketCorsConfigurationV2(ctx, "raw-uploads-bucket-cors", &s3.BucketCorsConfigurationV2Args{
 			Bucket: rawUploadsBucket.ID(),
 			CorsRules: s3.BucketCorsConfigurationV2CorsRuleArray{