Stop splicing whole SSE buffers into error text

pkg/authz/middleware.go

@@ -140,8 +140,8 @@ func shouldSkipSubsequentAuthorization(method string) bool {
 // "Unauthorized" message -- err (an authorizer failure) can carry policy detail that
 // security.md forbids returning to callers, so it is logged server-side instead.
 // Cedar's evaluation context can embed decoded JWT claim values (see the claim-keys-
-// only rule in authorizers/cedar/core.go), so err must never be promoted to a
-// structured field routed to an aggregator beyond this log line.
+// only rule in authorizers/cedar/core.go), so err must not be surfaced to the client,
+// nor copied into additional log lines or fields beyond the single Warn below.
 func handleUnauthorized(w http.ResponseWriter, msgID interface{}, err error) {
 	if err != nil {
 		slog.Warn("authorization denied", "error", err)

pkg/mcp/tool_filter.go

@@ -697,7 +697,9 @@ func processEventStream(
 	} else if len(buffer) >= 1 && buffer[len(buffer)-1] == '\r' {
 		linesep = []byte("\r")
 	} else {
-		return fmt.Errorf("unsupported separator: %s", string(buffer))
+		// Length only, not the buffer: buffer is the full pre-filter payload
+		// (e.g. the unfiltered tools/list), and this error is logged upstream.
+		return fmt.Errorf("unsupported SSE line separator in %d-byte buffer", len(buffer))
 	}
 
 	var linesepTotal, linesepCount int