feat(spi): add quoteIdentifierAlways to ISQLIdentifierProcessor

chat2db-community-server/chat2db-community-domain/chat2db-community-domain-core/src/main/java/ai/chat2db/community/domain/core/impl/db/DbSqlParserServiceImpl.java

@@ -362,10 +362,7 @@ public SqlContextParser contextParser(DbSqlContextParserRequest sqlContextParser
                     }
                     for (Token token : tokensOnDefault) {
                         String text = token.getText();
-                        if (text.startsWith(".")) {
-                            text = text.substring(1);
-                        }
-                        text = sqlIdentifierProcessor.removeIdentifierQuote(text);
+                        text = normalizeIdentifierToken(sqlIdentifierProcessor, text);
                         if (tableMap.containsKey(text)) {
                             SimpleTableColumnMapping simpleTableColumnMapping = new SimpleTableColumnMapping();
                             Table table = tableMap.get(text);
@@ -504,6 +501,14 @@ public SqlContextParser contextParser(DbSqlContextParserRequest sqlContextParser
         }
     }
 
+    static String normalizeIdentifierToken(ISQLIdentifierProcessor processor, String tokenText) {
+        if (tokenText == null) {
+            return null;
+        }
+        String identifier = tokenText.startsWith(".") ? tokenText.substring(1) : tokenText;
+        return processor.removeIdentifierQuote(identifier);
+    }
+
     @Override
     public List<SqlHover> sqlHover(DbSqlHoverRequest sqlHoverParam) {
         try {

chat2db-community-server/chat2db-community-domain/chat2db-community-domain-core/src/main/java/ai/chat2db/community/domain/core/impl/db/GenericSqlCompletionEngine.java

@@ -322,9 +322,9 @@ && matchesPattern(beforeSql + " " + afterSql, SELECT_TIP_COLUMN_FROM_PATTERN)) {
                     }
                 }
                 tableName = split[split.length - 1];
-                databaseName = sqlIdentifierProcessor.removeIdentifierQuote(databaseName);
-                schemaName = sqlIdentifierProcessor.removeIdentifierQuote(schemaName);
-                tableName = sqlIdentifierProcessor.removeIdentifierQuote(tableName);
+                databaseName = normalizeIdentifierPart(sqlIdentifierProcessor, databaseName);
+                schemaName = normalizeIdentifierPart(sqlIdentifierProcessor, schemaName);
+                tableName = normalizeIdentifierPart(sqlIdentifierProcessor, tableName);
                 tableAlias = sqlIdentifierProcessor.quoteIdentifier(tableAliasEntry.getValue());
                 if (supportDatabase && StringUtils.isBlank(databaseName)) {
                     continue;
@@ -551,17 +551,17 @@ private List<SqlCompletionCandidate> buildColumnCandidates(Map<String, String> t
                     databaseName = splitName[0];
                 }
             }
-            databaseName = processor.removeIdentifierQuote(databaseName);
+            databaseName = normalizeIdentifierPart(processor, databaseName);
             if (supportDatabase && StringUtils.isBlank(databaseName)) {
                 continue;
             }
-            schemaName = processor.removeIdentifierQuote(schemaName);
+            schemaName = normalizeIdentifierPart(processor, schemaName);
             if (supportSchema && StringUtils.isBlank(schemaName)) {
                 continue;
             }
             String lastIdentifier = splitName[length - 1];
             boolean quoted = processor.isQuoteIdentifier(lastIdentifier);
-            table = processor.removeIdentifierQuote(lastIdentifier);
+            table = normalizeIdentifierPart(processor, lastIdentifier);
             if (!quoted) {
                 table = processor.convertIdentifierCase(table);
             }
@@ -645,7 +645,7 @@ private List<SqlCompletionCandidate> buildIdentifierResult(CompletionInfo info,
         }
         String paramDatabaseName = param.getDatabaseName();
         String paramSchemaName = param.getSchemaName();
-        String lastName = processor.removeIdentifierQuote(names[names.length - 1]);
+        String lastName = normalizeIdentifierPart(processor, names[names.length - 1]);
         List<Database> databases = metaData.databases(connection);
         if (CollectionUtils.isNotEmpty(databases)) {
             for (Database database : databases) {
@@ -678,7 +678,7 @@ private List<SqlCompletionCandidate> buildIdentifierResult(CompletionInfo info,
         }
 
         String databaseName = names.length - 2 < 0 ? paramDatabaseName : names[names.length - 2];
-        databaseName = processor.removeIdentifierQuote(databaseName);
+        databaseName = normalizeIdentifierPart(processor, databaseName);
         List<Schema> schemas = metaData.schemas(connection, databaseName);
         if (CollectionUtils.isNotEmpty(schemas)) {
             for (Schema schema : schemas) {
@@ -713,8 +713,8 @@ private List<SqlCompletionCandidate> buildIdentifierResult(CompletionInfo info,
         if (supportSchema && StringUtils.isBlank(schemaName)) {
             return List.of();
         }
-        databaseName = processor.removeIdentifierQuote(databaseName);
-        schemaName = processor.removeIdentifierQuote(schemaName);
+        databaseName = normalizeIdentifierPart(processor, databaseName);
+        schemaName = normalizeIdentifierPart(processor, schemaName);
         String tableKey = getTableKey(dataSourceId, databaseName, schemaName);
         List<Table> tables = MemoryCacheManage.get(tableKey);
         if (CollectionUtils.isEmpty(tables)) {
@@ -791,6 +791,10 @@ private static SqlCompletionCandidate candidate(SqlCompletionCandidateTypeEnum t
         return SqlCompletionCandidate.of(type, label);
     }
 
+    static String normalizeIdentifierPart(ISQLIdentifierProcessor processor, String identifier) {
+        return identifier == null ? null : processor.removeIdentifierQuote(identifier);
+    }
+
     private int resolveCursor(DbSqlCompletionGetRequest param) {
         if (param.getCursor() != null) {
             return Math.max(0, Math.min(param.getCursor(), Objects.toString(param.getSql(), "").length()));

chat2db-community-server/chat2db-community-domain/chat2db-community-domain-core/src/test/java/ai/chat2db/community/domain/core/completion/SqlCompletionMetadataProviderAdapterTest.java

@@ -40,6 +40,15 @@ class SqlCompletionMetadataProviderAdapterTest {
 
     private final SqlCompletionConverter converter = new SqlCompletionConverterImpl();
 
+    @Test
+    void legacyIdentifierProcessorUsesCompatibleAlwaysQuoteDefault() {
+        BacktickIdentifierProcessor processor = new BacktickIdentifierProcessor();
+
+        Assertions.assertEquals("`a``b`", processor.quoteIdentifierAlways("a`b"));
+        Assertions.assertEquals("a`b",
+                processor.removeIdentifierQuote(processor.quoteIdentifierAlways("a`b")));
+    }
+
     @Test
     void listTablesUsesConverterAndPrefixFilter() {
         FakeMetaData metaData = new FakeMetaData();
@@ -245,12 +254,16 @@ public String quoteIdentifier(String identifier, Integer majorVersion, Integer m
 
         @Override
         public String quoteIdentifier(String identifier) {
-            return identifier == null ? null : "`" + identifier + "`";
+            return identifier == null ? null : "`" + identifier.replace("`", "``") + "`";
         }
 
         @Override
         public String removeIdentifierQuote(String identifier) {
-            return identifier == null ? null : identifier.replace("`", "");
+            if (identifier == null || identifier.length() < 2
+                    || !identifier.startsWith("`") || !identifier.endsWith("`")) {
+                return identifier;
+            }
+            return identifier.substring(1, identifier.length() - 1).replace("``", "`");
         }
 
         @Override

chat2db-community-server/chat2db-community-domain/chat2db-community-domain-core/src/test/java/ai/chat2db/community/domain/core/impl/db/GenericSqlCompletionEngineTest.java

@@ -0,0 +1,19 @@
+package ai.chat2db.community.domain.core.impl.db;
+
+import ai.chat2db.spi.DefaultSQLIdentifierProcessor;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+class GenericSqlCompletionEngineTest {
+
+    private final DefaultSQLIdentifierProcessor processor = new DefaultSQLIdentifierProcessor();
+
+    @Test
+    void normalizeIdentifierPartUnquotesOnlyOuterDelimiters() {
+        assertEquals("A\"B", GenericSqlCompletionEngine.normalizeIdentifierPart(processor, "\"A\"\"B\""));
+        assertEquals("A\"B", GenericSqlCompletionEngine.normalizeIdentifierPart(processor, "A\"B"));
+        assertNull(GenericSqlCompletionEngine.normalizeIdentifierPart(processor, null));
+    }
+}

chat2db-community-server/chat2db-community-domain/chat2db-community-domain-core/src/test/java/ai/chat2db/community/domain/core/impl/db/SqlParserServiceImplTest.java

@@ -3,6 +3,7 @@
 import ai.chat2db.community.domain.api.model.parser.statement.insert.InsertValueMapping;
 import ai.chat2db.community.domain.api.enums.parser.InsertValueMappingStatusEnum;
 import ai.chat2db.community.domain.api.model.db.SimpleInsertValueMapping;
+import ai.chat2db.spi.DefaultSQLIdentifierProcessor;
 import org.antlr.v4.runtime.CommonToken;
 import org.antlr.v4.runtime.Token;
 import org.junit.jupiter.api.Assertions;
@@ -13,6 +14,18 @@
 
 class SqlParserServiceImplTest {
 
+    @Test
+    void normalizeIdentifierTokenPreservesEmbeddedQuotes() {
+        DefaultSQLIdentifierProcessor processor = new DefaultSQLIdentifierProcessor();
+
+        Assertions.assertEquals("A\"B",
+                DbSqlParserServiceImpl.normalizeIdentifierToken(processor, "\"A\"\"B\""));
+        Assertions.assertEquals("A\"B",
+                DbSqlParserServiceImpl.normalizeIdentifierToken(processor, "A\"B"));
+        Assertions.assertEquals("Order",
+                DbSqlParserServiceImpl.normalizeIdentifierToken(processor, ".\"Order\""));
+    }
+
     @Test
     @SuppressWarnings("unchecked")
     void getSimpleInsertValueMappingsReturnsRowTokenRange() throws Exception {

chat2db-community-server/chat2db-community-plugins/chat2db-community-mysql/src/main/java/ai/chat2db/plugin/mysql/identifier/MysqlIdentifierProcessor.java

@@ -306,12 +306,26 @@ public String quoteIdentifier(String identifier) {
         return "`" + identifier + "`";
     }
 
+    @Override
+    public String quoteIdentifierAlways(String identifier) {
+        if (identifier == null) {
+            return null;
+        }
+        return "`" + identifier.replace("`", "``") + "`";
+    }
+
     @Override
     public String removeIdentifierQuote(String identifier) {
         if (StringUtils.isBlank(identifier)) {
             return identifier;
         }
-        return removePattern(identifier, MYSQL_PATTERN);
+        if (identifier.startsWith("`") && identifier.endsWith("`") && identifier.length() >= 2) {
+            return identifier.substring(1, identifier.length() - 1).replace("``", "`");
+        }
+        if (identifier.startsWith("\"") && identifier.endsWith("\"") && identifier.length() >= 2) {
+            return identifier.substring(1, identifier.length() - 1).replace("\"\"", "\"");
+        }
+        return identifier;
     }
 
     @Override

chat2db-community-server/chat2db-community-plugins/chat2db-community-mysql/src/test/java/ai/chat2db/plugin/mysql/identifier/MysqlIdentifierProcessorTest.java

@@ -0,0 +1,70 @@
+package ai.chat2db.plugin.mysql.identifier;
+
+import ai.chat2db.spi.DefaultSQLIdentifierProcessor;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+/**
+ * Contract tests for {@link MysqlIdentifierProcessor}.
+ * Covers the backtick-based {@code quoteIdentifierAlways} /
+ * {@code removeIdentifierQuote} round-trip and embedded-delimiter escaping.
+ */
+class MysqlIdentifierProcessorTest {
+
+    private final MysqlIdentifierProcessor processor = new MysqlIdentifierProcessor();
+
+    @Test
+    void quoteIdentifierAlways_wrapsInBacktick() {
+        assertEquals("`mycol`", processor.quoteIdentifierAlways("mycol"));
+    }
+
+    @Test
+    void quoteIdentifierAlways_escapesEmbeddedBacktick() {
+        assertEquals("`a``b`", processor.quoteIdentifierAlways("a`b"));
+    }
+
+    @Test
+    void quoteIdentifierAlways_preservesMixedCase() {
+        assertEquals("`MixedCase`", processor.quoteIdentifierAlways("MixedCase"));
+    }
+
+    @Test
+    void quoteIdentifierAlways_handlesNull() {
+        assertNull(processor.quoteIdentifierAlways(null));
+    }
+
+    @Test
+    void removeIdentifierQuote_stripsBacktick() {
+        assertEquals("mycol", processor.removeIdentifierQuote("`mycol`"));
+    }
+
+    @Test
+    void removeIdentifierQuote_unescapesBacktick() {
+        assertEquals("a`b", processor.removeIdentifierQuote("`a``b`"));
+    }
+
+    @Test
+    void removeIdentifierQuote_stripsDoubleQuote() {
+        assertEquals("mycol", processor.removeIdentifierQuote("\"mycol\""));
+    }
+
+    @Test
+    void roundTrip_plainName() {
+        String raw = "mycol";
+        assertEquals(raw, processor.removeIdentifierQuote(processor.quoteIdentifierAlways(raw)));
+    }
+
+    @Test
+    void roundTrip_embeddedBacktick() {
+        String raw = "a`b";
+        assertEquals(raw, processor.removeIdentifierQuote(processor.quoteIdentifierAlways(raw)));
+    }
+
+    @Test
+    void roundTrip_mixedCase() {
+        String raw = "MixedCase";
+        assertEquals(raw, processor.removeIdentifierQuote(processor.quoteIdentifierAlways(raw)));
+    }
+}

chat2db-community-server/chat2db-community-plugins/chat2db-community-sqlserver/src/main/java/ai/chat2db/plugin/sqlserver/identifier/SqlServerIdentifierProcessor.java

@@ -219,12 +219,26 @@ public String quoteIdentifier(String identifier) {
         return "[" + identifier + "]";
     }
 
+    @Override
+    public String quoteIdentifierAlways(String identifier) {
+        if (identifier == null) {
+            return null;
+        }
+        return "[" + identifier.replace("]", "]]") + "]";
+    }
+
     @Override
     public String removeIdentifierQuote(String identifier) {
         if (StringUtils.isBlank(identifier)) {
             return identifier;
         }
-        return removePattern(identifier, SQL_SERVER_PATTERN);
+        if (identifier.startsWith("[") && identifier.endsWith("]") && identifier.length() >= 2) {
+            return identifier.substring(1, identifier.length() - 1).replace("]]", "]");
+        }
+        if (identifier.startsWith("\"") && identifier.endsWith("\"") && identifier.length() >= 2) {
+            return identifier.substring(1, identifier.length() - 1).replace("\"\"", "\"");
+        }
+        return identifier;
     }
 
     @Override

chat2db-community-server/chat2db-community-plugins/chat2db-community-sqlserver/src/test/java/ai/chat2db/plugin/sqlserver/identifier/SqlServerIdentifierProcessorTest.java

@@ -0,0 +1,69 @@
+package ai.chat2db.plugin.sqlserver.identifier;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+/**
+ * Contract tests for {@link SqlServerIdentifierProcessor}.
+ * Covers the bracket-based {@code quoteIdentifierAlways} /
+ * {@code removeIdentifierQuote} round-trip and embedded-delimiter escaping.
+ */
+class SqlServerIdentifierProcessorTest {
+
+    private final SqlServerIdentifierProcessor processor = new SqlServerIdentifierProcessor();
+
+    @Test
+    void quoteIdentifierAlways_wrapsInBrackets() {
+        assertEquals("[mycol]", processor.quoteIdentifierAlways("mycol"));
+    }
+
+    @Test
+    void quoteIdentifierAlways_preservesMixedCase() {
+        assertEquals("[MixedCase]", processor.quoteIdentifierAlways("MixedCase"));
+    }
+
+    @Test
+    void quoteIdentifierAlways_escapesEmbeddedCloseBracket() {
+        assertEquals("[a]]b]", processor.quoteIdentifierAlways("a]b"));
+    }
+
+    @Test
+    void quoteIdentifierAlways_handlesNull() {
+        assertNull(processor.quoteIdentifierAlways(null));
+    }
+
+    @Test
+    void removeIdentifierQuote_stripsBrackets() {
+        assertEquals("mycol", processor.removeIdentifierQuote("[mycol]"));
+    }
+
+    @Test
+    void removeIdentifierQuote_unescapesCloseBracket() {
+        assertEquals("a]b", processor.removeIdentifierQuote("[a]]b]"));
+    }
+
+    @Test
+    void removeIdentifierQuote_stripsDoubleQuote() {
+        assertEquals("mycol", processor.removeIdentifierQuote("\"mycol\""));
+    }
+
+    @Test
+    void roundTrip_plainName() {
+        String raw = "mycol";
+        assertEquals(raw, processor.removeIdentifierQuote(processor.quoteIdentifierAlways(raw)));
+    }
+
+    @Test
+    void roundTrip_embeddedCloseBracket() {
+        String raw = "a]b";
+        assertEquals(raw, processor.removeIdentifierQuote(processor.quoteIdentifierAlways(raw)));
+    }
+
+    @Test
+    void roundTrip_mixedCase() {
+        String raw = "MixedCase";
+        assertEquals(raw, processor.removeIdentifierQuote(processor.quoteIdentifierAlways(raw)));
+    }
+}