fix(mysql): support compatible explain formats

apps/desktop/src/lib/diagram/mysqlExplainCompatibility.ts

@@ -0,0 +1,40 @@
+import { formatError } from "@/lib/backend/errorUtils";
+
+export interface MysqlExplainCompatibilityHint {
+  fallbackSql?: string;
+  supportsJson: boolean;
+}
+
+const INVALID_EXPLAIN_OPTION_RE = /invalid\s+explain\s+option/i;
+const VALID_EXPLAIN_OPTIONS_RE = /valid\s+options\s+are\s*:\s*\[([^\]]+)\]/i;
+const EXPLAIN_FORMAT_PREFIX_RE = /^EXPLAIN\s+FORMAT\s*=\s*[A-Z_]+\s+/i;
+
+export function mysqlExplainCompatibilityHint(error: unknown, explainSql: string): MysqlExplainCompatibilityHint | undefined {
+  const message = formatError(error);
+  if (!INVALID_EXPLAIN_OPTION_RE.test(message)) return undefined;
+
+  const optionsMatch = message.match(VALID_EXPLAIN_OPTIONS_RE);
+  if (!optionsMatch) return undefined;
+
+  const validFormats = new Set(
+    optionsMatch[1]
+      .split(",")
+      .map((format) =>
+        format
+          .trim()
+          .replace(/^['"`]|['"`]$/g, "")
+          .toUpperCase(),
+      )
+      .filter(Boolean),
+  );
+  const formatPrefixMatch = explainSql.match(EXPLAIN_FORMAT_PREFIX_RE);
+  if (!formatPrefixMatch) return { supportsJson: validFormats.has("JSON") };
+
+  // MySQL-compatible warehouses often expose TEXT as their tabular EXPLAIN format instead of TRADITIONAL.
+  const fallbackPrefix = validFormats.has("TEXT") ? "EXPLAIN FORMAT=TEXT " : "EXPLAIN ";
+  const fallbackSql = explainSql.replace(EXPLAIN_FORMAT_PREFIX_RE, fallbackPrefix);
+  return {
+    fallbackSql: fallbackSql === explainSql ? undefined : fallbackSql,
+    supportsJson: validFormats.has("JSON"),
+  };
+}