fix(query-parser): honor phrase prefix and slop on JSON fields

Phrase prefix (`"..."*`) and slop (`"..."~N`) were silently dropped on JSON
fields. `generate_literals_for_json_object` hard-coded `slop: 0` and
`prefix: false`, so a query like `data.name:"foo bar"*` degraded to an exact
phrase, even though the underlying `PhrasePrefixQuery` already supports
JSON-path terms.

Thread `slop`/`prefix` through the JSON branch, exactly as the `Str` branch
already does, and add the "phrase prefix requires at least two terms" guard for
the single-token case (mirroring `generate_literals_for_str`).

Tests added as JSON analogues of the existing text-field tests:
- test_phrase_prefix_on_json_field
- test_phrase_prefix_too_short_on_json_field
- test_phrase_slop_on_json_field

This aligns JSON fields with the phrase `~`/`*` behavior already documented for
`QueryParser`.

Author: DavIvek

CHANGELOG.md

@@ -17,6 +17,7 @@ Tantivy 0.26 (Unreleased)
 - Fix integer overflow in segment sorting and merge policy truncation [#2846](https://github.com/quickwit-oss/tantivy/pull/2846)(@anaslimem)
 - Fix merging of intermediate aggregation results [#2719](https://github.com/quickwit-oss/tantivy/pull/2719)(@PSeitz)
 - Fix deduplicate doc counts in term aggregation for multi-valued fields [#2854](https://github.com/quickwit-oss/tantivy/pull/2854)(@nuri-yoo)
+- Honor phrase prefix (`"..."*`) and slop (`"..."~N`) on JSON fields; previously both were silently dropped, degrading the query to an exact phrase [#XXXX](https://github.com/quickwit-oss/tantivy/pull/XXXX)(@DavIvek)
 
 ## Features/Improvements
 - **Aggregation**

src/query/query_parser/query_parser.rs

@@ -602,6 +602,8 @@ impl QueryParser {
                 field,
                 json_path,
                 phrase,
+                slop,
+                prefix,
                 &self.tokenizer_manager,
                 json_options,
             ),
@@ -995,11 +997,14 @@ fn generate_literals_for_str(
     }))
 }
 
+#[expect(clippy::too_many_arguments)]
 fn generate_literals_for_json_object(
     field_name: &str,
     field: Field,
     json_path: &str,
     phrase: &str,
+    slop: u32,
+    prefix: bool,
     tokenizer_manager: &TokenizerManager,
     json_options: &JsonObjectOptions,
 ) -> Result<Vec<LogicalLiteral>, QueryParserError> {
@@ -1036,6 +1041,12 @@ fn generate_literals_for_json_object(
     });
 
     if positions_and_terms.len() <= 1 {
+        if prefix {
+            return Err(QueryParserError::PhrasePrefixRequiresAtLeastTwoTerms {
+                phrase: phrase.to_owned(),
+                tokenizer: text_options.tokenizer().to_owned(),
+            });
+        }
         for (_, term) in positions_and_terms {
             logical_literals.push(LogicalLiteral::Term(term));
         }
@@ -1048,8 +1059,8 @@ fn generate_literals_for_json_object(
     }
     logical_literals.push(LogicalLiteral::Phrase {
         terms: positions_and_terms,
-        slop: 0,
-        prefix: false,
+        slop,
+        prefix,
     });
     Ok(logical_literals)
 }
@@ -1963,6 +1974,42 @@ mod test {
         );
     }
 
+    #[test]
+    pub fn test_phrase_prefix_on_json_field() {
+        let query_parser = make_query_parser();
+        let query = query_parser
+            .parse_query("json.attr:\"big bad wo\"*")
+            .unwrap();
+        assert_eq!(
+            format!("{query:?}"),
+            "PhrasePrefixQuery { field: Field(14), phrase_terms: [(0, Term(field=14, type=Json, \
+             path=attr, type=Str, \"big\")), (1, Term(field=14, type=Json, path=attr, type=Str, \
+             \"bad\"))], prefix: (2, Term(field=14, type=Json, path=attr, type=Str, \"wo\")), \
+             max_expansions: 50 }"
+        );
+    }
+
+    #[test]
+    pub fn test_phrase_prefix_too_short_on_json_field() {
+        let err = parse_query_to_logical_ast("json.attr:\"wo\"*", true).unwrap_err();
+        assert_eq!(
+            err,
+            QueryParserError::PhrasePrefixRequiresAtLeastTwoTerms {
+                phrase: "wo".to_owned(),
+                tokenizer: "default".to_owned()
+            }
+        );
+    }
+
+    #[test]
+    pub fn test_phrase_slop_on_json_field() {
+        test_parse_query_to_logical_ast_helper(
+            "json.attr:\"a b\"~2",
+            r#""[(0, Term(field=14, type=Json, path=attr, type=Str, "a")), (1, Term(field=14, type=Json, path=attr, type=Str, "b"))]"~2"#,
+            false,
+        );
+    }
+
     #[test]
     pub fn test_term_set_query() {
         test_parse_query_to_logical_ast_helper(