fix(responsecache): tighten SSE validation

SantiagoDePolonia · SantiagoDePolonia · commit 58b999c92f3e · 2026-04-02T10:33:37.000+02:00
diff --git a/internal/responsecache/sse_validation.go b/internal/responsecache/sse_validation.go
@@ -26,6 +26,9 @@ func validateCacheableSSE(raw []byte) bool {
 		raw = raw[idx+sepLen:]
 
 		payload, hasData := sseEventPayload(event)
+		if sawDone {
+			return false
+		}
 		if !hasData {
 			continue
 		}
@@ -36,12 +39,7 @@ func validateCacheableSSE(raw []byte) bool {
 			sawDone = true
 			continue
 		}
-		if sawDone {
-			return false
-		}
-
-		var decoded map[string]any
-		if err := json.Unmarshal(payload, &decoded); err != nil {
+		if !json.Valid(payload) {
 			return false
 		}
 		sawJSONPayload = true
diff --git a/internal/responsecache/sse_validation_test.go b/internal/responsecache/sse_validation_test.go
@@ -10,6 +10,11 @@ func TestValidateCacheableSSE(t *testing.T) {
 		raw  []byte
 		want bool
 	}{
+		{
+			name: "rejects empty input",
+			raw:  []byte(""),
+			want: false,
+		},
 		{
 			name: "valid chat stream",
 			raw: []byte(
@@ -52,6 +57,15 @@ func TestValidateCacheableSSE(t *testing.T) {
 			),
 			want: false,
 		},
+		{
+			name: "rejects keepalive after done",
+			raw: []byte(
+				"data: {\"type\":\"response.created\",\"response\":{\"id\":\"resp-1\"}}\n\n" +
+					"data: [DONE]\n\n" +
+					": keep-alive\n\n",
+			),
+			want: false,
+		},
 		{
 			name: "rejects trailing partial event",
 			raw: []byte(
diff --git a/internal/responsecache/stream_cache.go b/internal/responsecache/stream_cache.go
@@ -2,9 +2,7 @@ package responsecache
 
 import (
 	"bytes"
-	"context"
 	"encoding/json"
-	"errors"
 	"net/http"
 	"sort"
 	"strings"
@@ -126,25 +124,6 @@ func cacheKeyRequestBody(path string, body []byte) []byte {
 	}
 }
 
-func streamResponseDefaultsFromContext(ctx context.Context) streamResponseDefaults {
-	var defaults streamResponseDefaults
-
-	plan := core.GetExecutionPlan(ctx)
-	if plan == nil {
-		return defaults
-	}
-
-	defaults.Provider = strings.TrimSpace(plan.ProviderType)
-	if plan.Resolution != nil {
-		if defaults.Provider == "" {
-			defaults.Provider = strings.TrimSpace(plan.Resolution.ResolvedSelector.Provider)
-		}
-		defaults.Model = strings.TrimSpace(plan.Resolution.ResolvedSelector.Model)
-	}
-
-	return defaults
-}
-
 func isEventStreamContentType(contentType string) bool {
 	if contentType == "" {
 		return false
@@ -172,17 +151,6 @@ func writeCachedResponse(c *echo.Context, path string, requestBody, cached []byt
 	return nil
 }
 
-func renderCachedStream(path string, requestBody, cached []byte) ([]byte, error) {
-	switch path {
-	case "/v1/chat/completions":
-		return renderCachedChatStream(requestBody, cached)
-	case "/v1/responses":
-		return renderCachedResponsesStream(requestBody, cached)
-	default:
-		return nil, errors.New("cached streaming replay is not supported for this path")
-	}
-}
-
 func renderCachedChatStream(requestBody, cached []byte) ([]byte, error) {
 	var resp core.ChatResponse
 	if err := json.Unmarshal(cached, &resp); err != nil {
