Fix CSV-escaped quotes in generated docs examples

docs/changelog/143449.yaml

@@ -0,0 +1,5 @@
+pr: 143449
+summary: Fix CSV-escaped quotes rendering in generated ES|QL docs examples
+area: ES|QL
+type: bug
+issues: []

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/DocsV3Support.java

@@ -1896,8 +1896,17 @@ private String renderTableLine(String[] columns) {
             if (i > 0) {
                 sb.append(" | ");
             }
+            String cell = columns[i].trim();
+            // Unescape RFC 4180 CSV-quoted values that contain doubled quotes ("").
+            // In CSV spec results, a value like "{""key"":""val""}" uses outer " as field delimiters
+            // and "" as escaped ". We strip the delimiters and unescape so JSON renders correctly
+            // in docs (e.g. {"key":"value"} instead of {""key"":""value""}).
+            // Simple quoted values like "POINT(...)" have no "" inside and are left unchanged.
+            if (cell.startsWith("\"") && cell.endsWith("\"") && cell.substring(1, cell.length() - 1).contains("\"\"")) {
+                cell = cell.substring(1, cell.length() - 1).replace("\"\"", "\"");
+            }
             // Some cells have regex content (see CATEGORIZE), so we need to escape this
-            sb.append(columns[i].trim().replaceAll("\\.\\*", ".\\\\*"));
+            sb.append(cell.replaceAll("\\.\\*", ".\\\\*"));
         }
         return sb.append(" |\n").toString();
     }

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/DocsV3SupportTests.java

@@ -213,6 +213,34 @@ public void testRenderingExampleResultRaw() throws IOException {
         assertThat(results, equalTo(expectedResults));
     }
 
+    /**
+     * Verify that RFC 4180 CSV-quoted values with doubled quotes are properly unescaped,
+     * so JSON strings render correctly in docs instead of showing {""key"":""value""}.
+     */
+    public void testRenderingExampleResultCsvJsonUnescaping() throws IOException {
+        String expectedResults = """
+            | log:keyword | severity:keyword |
+            | --- | --- |
+            | {"severity":"ERROR","body":"Payment processing failed"} | ERROR |
+            """;
+        String results = docs.loadExample("json_extract.csv-spec", "json_extract-result");
+        assertThat(results, equalTo(expectedResults));
+    }
+
+    /**
+     * Verify that simple quoted values (no doubled quotes inside) are preserved as-is.
+     * Only values with "" (RFC 4180 escaping) should be unescaped.
+     */
+    public void testRenderingExampleResultSimpleQuotesPreserved() throws IOException {
+        String expectedResults = """
+            | wkt:keyword | pt:geo_point |
+            | --- | --- |
+            | "POINT(42.97109630194 14.7552534413725)" | POINT(42.97109630194 14.7552534413725) |
+            """;
+        String results = docs.loadExample("spatial.csv-spec", "to_geopoint-str-result");
+        assertThat(results, equalTo(expectedResults));
+    }
+
     public void testRenderingExampleRaw2() throws IOException {
         String expectedExample = """
             ROW n=1