[log] Add debug logging to GraphQL owner/repo and search query extraction

internal/proxy/graphql.go

@@ -155,6 +155,7 @@ func extractOwnerRepo(variables map[string]interface{}, query string) (string, s
 		if v, ok := variables["repo"].(string); ok && repo == "" {
 			repo = v
 		}
+		logGraphQL.Printf("extractOwnerRepo: from variables: owner=%q repo=%q", owner, repo)
 	}
 
 	// Fall back to parsing the query string
@@ -166,6 +167,7 @@ func extractOwnerRepo(variables map[string]interface{}, query string) (string, s
 			if m[2] != "" && repo == "" {
 				repo = m[2]
 			}
+			logGraphQL.Printf("extractOwnerRepo: from query regex: owner=%q repo=%q", owner, repo)
 		}
 	}
 
@@ -187,19 +189,34 @@ func extractOwnerRepo(variables map[string]interface{}, query string) (string, s
 // searchQueryArgPattern extracts the literal query string from search(query:"...", ...)
 var searchQueryArgPattern = regexp.MustCompile(`(?i)\bsearch\s*\(\s*query\s*:\s*"([^"]+)"`)
 
+// truncateForLog truncates s to at most maxRunes runes, for safe debug logging.
+func truncateForLog(s string, maxRunes int) string {
+	if maxRunes <= 0 {
+		return ""
+	}
+	r := []rune(s)
+	if len(r) <= maxRunes {
+		return s
+	}
+	return string(r[:maxRunes])
+}
+
 // extractSearchQuery returns the search query argument from a GraphQL search
 // query. It checks variables ($query) first, then inline query text.
 func extractSearchQuery(query string, variables map[string]interface{}) string {
 	// Check variables for $query
 	if variables != nil {
 		if v, ok := variables["query"].(string); ok && v != "" {
+			logGraphQL.Printf("extractSearchQuery: found in variables: %q", truncateForLog(v, 80))
 			return v
 		}
 	}
 	// Parse inline: search(query:"repo:owner/name is:issue", ...)
 	if m := searchQueryArgPattern.FindStringSubmatch(query); m != nil {
+		logGraphQL.Printf("extractSearchQuery: found inline: %q", truncateForLog(m[1], 80))
 		return m[1]
 	}
+	logGraphQL.Print("extractSearchQuery: no search query found")
 	return ""
 }