build(server): upgrade to Spring Boot 4 (Jackson 3, Framework 7)

AGENTS.md

@@ -30,9 +30,9 @@ cuckoodb-parent/                       # repo root (git slug: java-query-engine)
 │           ├── ConcurrentQueryExecutionTest.java, DBCatalogTest.java, ...   # planner / optimizer / budget / EXPLAIN / end-to-end
 │           ├── operator/                           # operator-level tests + CachedOperator test utility
 │           └── bench/                              # JMH benchmarks (compiled in CI, never run there): EndToEndJoinBenchmark, JoinAlgorithmBenchmark
-└── server/                            # cuckoodb-server — REST gateway skeleton; Spring Boot REST gateway planned
-    ├── pom.xml                        # depends on cuckoodb-engine (${project.version}); NO Spring yet
-    └── src/main/java/com/github/jinba1/cuckoodb/server/ServerPlaceholder.java   # compile-links an engine type to prove reactor wiring
+└── server/                            # cuckoodb-server — Spring Boot 4 REST gateway over the engine
+    ├── pom.xml                        # depends on cuckoodb-engine; Spring Boot 4.0.7 (web MVC), springdoc/OpenAPI
+    └── src/main/java/com/github/jinba1/cuckoodb/server/   # web/ controllers + GlobalExceptionHandler, query/ QueryService+budget+concurrency, catalog/ CatalogFacade, audit/ sink, config/ (52 server tests)
 ```
 
 Per-file responsibilities are in the WHERE TO LOOK table below.

README.md

@@ -273,9 +273,9 @@ The test suite covers individual operators, the query planner, the optimiser, ex
 │       ├── db/data/                                 # CSV data files (header row + data rows)
 │       ├── input/query[1-20].sql                    # Sample queries
 │       └── expected_output/query[1-20].csv          # Expected results
-├── server/                                          # REST gateway skeleton — Spring Boot REST gateway planned
-│   ├── pom.xml                                      # cuckoodb-server (depends on cuckoodb-engine; no Spring yet)
-│   └── src/main/java/com/github/jinba1/cuckoodb/server/
+├── server/                                          # cuckoodb-server — Spring Boot REST gateway over the engine
+│   ├── pom.xml                                      # Spring Boot 4 (web MVC), springdoc/OpenAPI
+│   └── src/main/java/com/github/jinba1/cuckoodb/server/   # controllers, query service, catalog facade, config
 ├── mvnw / mvnw.cmd                                  # Maven Wrapper
 └── LICENSE
 ```

server/pom.xml

@@ -23,8 +23,11 @@
   -->
 
   <properties>
-    <spring-boot.version>3.4.1</spring-boot.version>
-    <springdoc.version>2.7.0</springdoc.version>
+    <spring-boot.version>4.0.7</spring-boot.version>
+    <!-- springdoc 3.0.3 is the Boot-4/Jackson-3 line; verified compatible with Boot 4.0.7
+         (full @SpringBootTest contexts load with springdoc auto-config; no MVC API-versioning,
+         so springdoc #3163 does not apply). -->
+    <springdoc.version>3.0.3</springdoc.version>
   </properties>
 
   <dependencyManagement>
@@ -47,7 +50,7 @@
     </dependency>
     <dependency>
       <groupId>org.springframework.boot</groupId>
-      <artifactId>spring-boot-starter-web</artifactId>
+      <artifactId>spring-boot-starter-webmvc</artifactId>
     </dependency>
     <dependency>
       <groupId>org.springdoc</groupId>
@@ -59,6 +62,34 @@
       <artifactId>spring-boot-starter-test</artifactId>
       <scope>test</scope>
     </dependency>
+    <!--
+      Boot 4 split the @WebMvcTest slice out of spring-boot-starter-test into a per-technology
+      test starter; QueryControllerTest/TableControllerTest need it for the controller slice.
+    -->
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-webmvc-test</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <!--
+      Boot 4 relocated TestRestTemplate/RestTestClient to org.springframework.boot.resttestclient
+      and no longer auto-configures the client under @SpringBootTest. The 4 RANDOM_PORT integration
+      tests keep TestRestTemplate (behaviour-preserving) via this dependency + @AutoConfigureTestRestTemplate.
+    -->
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-resttestclient</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <!--
+      TestRestTemplate's auto-config needs org.springframework.boot.restclient.RestTemplateBuilder,
+      which spring-boot-resttestclient does not pull transitively (Boot #48588) — declare it explicitly.
+    -->
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-restclient</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>

server/src/test/java/com/github/jinba1/cuckoodb/server/web/BudgetIntegrationTest.java

@@ -4,7 +4,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import com.fasterxml.jackson.databind.ObjectMapper;
+import tools.jackson.databind.ObjectMapper;
 
 import java.io.IOException;
 import java.nio.file.Files;
@@ -14,7 +14,8 @@
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.boot.resttestclient.TestRestTemplate;
+import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureTestRestTemplate;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
@@ -31,6 +32,7 @@
  */
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
 @DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_CLASS)
+@AutoConfigureTestRestTemplate
 class BudgetIntegrationTest {
 
     private static final ObjectMapper JSON = new ObjectMapper();
@@ -67,8 +69,8 @@ void omittedBudgetStillEnforcesTheDefault() throws Exception {
         // which a 4-row scan exceeds. A 200 here would mean the unbounded path was reachable.
         ResponseEntity<String> resp = postQuery("{\"sql\":\"SELECT * FROM People\"}");
         assertEquals(429, resp.getStatusCode().value(), resp.getBody());
-        assertEquals("BUDGET_EXCEEDED", JSON.readTree(resp.getBody()).get("errorCode").asText());
-        assertTrue(resp.getHeaders().containsKey("Retry-After"));
+        assertEquals("BUDGET_EXCEEDED", JSON.readTree(resp.getBody()).get("errorCode").asString());
+        assertTrue(resp.getHeaders().containsHeader("Retry-After"));
     }
 
     @Test
@@ -77,15 +79,15 @@ void hugeClientBudgetIsClampedToCapAndStillTrips() throws Exception {
         ResponseEntity<String> resp = postQuery(
                 "{\"sql\":\"SELECT * FROM People\",\"maxTuples\":9999999}");
         assertEquals(429, resp.getStatusCode().value(), resp.getBody());
-        assertEquals("BUDGET_EXCEEDED", JSON.readTree(resp.getBody()).get("errorCode").asText());
+        assertEquals("BUDGET_EXCEEDED", JSON.readTree(resp.getBody()).get("errorCode").asString());
     }
 
     @Test
     void explainConsumesNoBudget() throws Exception {
         // EXPLAIN performs no execution, so the tiny budget never bites: a plan comes back 200.
         ResponseEntity<String> resp = postQuery("{\"sql\":\"EXPLAIN SELECT * FROM People\"}");
         assertEquals(200, resp.getStatusCode().value(), resp.getBody());
-        assertTrue(JSON.readTree(resp.getBody()).get("explain").asText().contains("Plan"));
+        assertTrue(JSON.readTree(resp.getBody()).get("explain").asString().contains("Plan"));
     }
 
     private ResponseEntity<String> postQuery(String json) {

server/src/test/java/com/github/jinba1/cuckoodb/server/web/QueryApiIntegrationTest.java

@@ -6,8 +6,8 @@
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import com.fasterxml.jackson.databind.JsonNode;
-import com.fasterxml.jackson.databind.ObjectMapper;
+import tools.jackson.databind.JsonNode;
+import tools.jackson.databind.ObjectMapper;
 
 import java.io.IOException;
 import java.nio.file.Files;
@@ -23,7 +23,8 @@
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.boot.resttestclient.TestRestTemplate;
+import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureTestRestTemplate;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
@@ -42,6 +43,7 @@
  */
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
 @DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_CLASS)
+@AutoConfigureTestRestTemplate
 class QueryApiIntegrationTest {
 
     private static final ObjectMapper JSON = new ObjectMapper();
@@ -81,11 +83,11 @@ void syncQueryRoundTripReturnsTypedColumnArrays() throws Exception {
         JsonNode body = postQuery("{\"sql\":\"SELECT * FROM People\"}", 200);
         assertEquals(3, body.get("rowCount").asInt());
         assertFalse(body.get("truncated").asBoolean());
-        assertEquals("id", body.get("columns").get(0).get("name").asText());
-        assertEquals("INT", body.get("columns").get(0).get("type").asText());
-        assertEquals("STRING", body.get("columns").get(1).get("type").asText());
+        assertEquals("id", body.get("columns").get(0).get("name").asString());
+        assertEquals("INT", body.get("columns").get(0).get("type").asString());
+        assertEquals("STRING", body.get("columns").get(1).get("type").asString());
         assertEquals(1, body.get("rows").get(0).get(0).asInt());
-        assertEquals("alice", body.get("rows").get(0).get(1).asText());
+        assertEquals("alice", body.get("rows").get(0).get(1).asString());
     }
 
     @Test
@@ -99,15 +101,15 @@ void limitMarksResultTruncated() throws Exception {
     @Test
     void explainReturnsPlanWithNoRowsAndNoRowCount() throws Exception {
         JsonNode body = postQuery("{\"sql\":\"EXPLAIN SELECT * FROM People\"}", 200);
-        assertTrue(body.get("explain").asText().contains("Plan (as written)"));
+        assertTrue(body.get("explain").asString().contains("Plan (as written)"));
         assertFalse(body.has("rows"), "EXPLAIN performs no execution, so rows is absent");
         assertFalse(body.has("rowCount"));
     }
 
     @Test
     void unknownTableInQueryBodyIs422() throws Exception {
         JsonNode body = postQuery("{\"sql\":\"SELECT * FROM Nope\"}", 422);
-        assertEquals("UNKNOWN_TABLE", body.get("errorCode").asText());
+        assertEquals("UNKNOWN_TABLE", body.get("errorCode").asString());
     }
 
     @Test
@@ -124,7 +126,7 @@ void queryPathDataErrorReturns500WithNoFilesystemPath() throws Exception {
         assertFalse(raw.contains(dataDir.toString()), "5xx body leaked a filesystem path: " + raw);
         JsonNode body = JSON.readTree(raw);
         assertNotNull(body.get("errorId"), "5xx carries a correlation id");
-        assertEquals("Internal server error.", body.get("message").asText());
+        assertEquals("Internal server error.", body.get("message").asString());
     }
 
     @Test

server/src/test/java/com/github/jinba1/cuckoodb/server/web/QueryControllerTest.java

@@ -31,7 +31,7 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.boot.webmvc.test.autoconfigure.WebMvcTest;
 import org.springframework.http.MediaType;
 import org.springframework.test.context.bean.override.mockito.MockitoBean;
 import org.springframework.test.web.servlet.MockMvc;

server/src/test/java/com/github/jinba1/cuckoodb/server/web/TableControllerTest.java

@@ -14,7 +14,7 @@
 
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.boot.webmvc.test.autoconfigure.WebMvcTest;
 import org.springframework.test.context.bean.override.mockito.MockitoBean;
 import org.springframework.test.web.servlet.MockMvc;
 

server/src/test/java/com/github/jinba1/cuckoodb/server/web/UploadApiIntegrationTest.java

@@ -5,8 +5,8 @@
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 
-import com.fasterxml.jackson.databind.JsonNode;
-import com.fasterxml.jackson.databind.ObjectMapper;
+import tools.jackson.databind.JsonNode;
+import tools.jackson.databind.ObjectMapper;
 
 import java.io.IOException;
 import java.nio.file.Files;
@@ -16,7 +16,8 @@
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.boot.resttestclient.TestRestTemplate;
+import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureTestRestTemplate;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
@@ -33,6 +34,7 @@
  */
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
 @DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_CLASS)
+@AutoConfigureTestRestTemplate
 class UploadApiIntegrationTest {
 
     private static final ObjectMapper JSON = new ObjectMapper();
@@ -67,10 +69,10 @@ void uploadThenQueryRoundTrips() throws Exception {
         ResponseEntity<String> upload = csv("/tables/Widgets", "sku,qty\nA,5\nB,7\n");
         assertEquals(201, upload.getStatusCode().value(), upload.getBody());
         JsonNode created = JSON.readTree(upload.getBody());
-        assertEquals("Widgets", created.get("name").asText());
+        assertEquals("Widgets", created.get("name").asString());
         assertEquals(2, created.get("rowCount").asInt());
-        assertEquals("qty", created.get("columns").get(1).get("name").asText());
-        assertEquals("INT", created.get("columns").get(1).get("type").asText());
+        assertEquals("qty", created.get("columns").get(1).get("name").asString());
+        assertEquals("INT", created.get("columns").get(1).get("type").asString());
 
         // The freshly uploaded table is immediately queryable.
         ResponseEntity<String> query = exchange("/queries", HttpMethod.POST,
@@ -82,7 +84,7 @@ void uploadThenQueryRoundTrips() throws Exception {
         ResponseEntity<String> describe = rest.getForEntity("/tables/Widgets", String.class);
         assertEquals(200, describe.getStatusCode().value());
         assertEquals("STRING", JSON.readTree(describe.getBody())
-                .get("columns").get(0).get("type").asText(), "sku column is string-typed");
+                .get("columns").get(0).get("type").asString(), "sku column is string-typed");
     }
 
     @Test
@@ -141,7 +143,7 @@ void malformedCsvReturns400WithNoFilesystemPath() throws Exception {
         String raw = resp.getBody();
         assertNotNull(raw);
         assertFalse(raw.contains(workDir.toString()), "upload 400 leaked a work-dir path: " + raw);
-        assertEquals("DATA_ERROR", JSON.readTree(raw).get("errorCode").asText());
+        assertEquals("DATA_ERROR", JSON.readTree(raw).get("errorCode").asString());
     }
 
     private ResponseEntity<String> csv(String path, String body) {

server/src/test/java/com/github/jinba1/cuckoodb/server/web/UploadLimitIntegrationTest.java

@@ -4,7 +4,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 
-import com.fasterxml.jackson.databind.ObjectMapper;
+import tools.jackson.databind.ObjectMapper;
 
 import java.io.IOException;
 import java.nio.file.Files;
@@ -14,7 +14,8 @@
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
-import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.boot.resttestclient.TestRestTemplate;
+import org.springframework.boot.resttestclient.autoconfigure.AutoConfigureTestRestTemplate;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
@@ -29,6 +30,7 @@
  */
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
 @DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_CLASS)
+@AutoConfigureTestRestTemplate
 class UploadLimitIntegrationTest {
 
     private static final ObjectMapper JSON = new ObjectMapper();
@@ -64,9 +66,9 @@ void uploadOverTableCapReturns507() throws Exception {
 
         ResponseEntity<String> overCap = csv("/tables/Second", "x\n1\n");
         assertEquals(507, overCap.getStatusCode().value(), overCap.getBody());
-        assertEquals("TABLE_LIMIT", JSON.readTree(overCap.getBody()).get("errorCode").asText());
+        assertEquals("TABLE_LIMIT", JSON.readTree(overCap.getBody()).get("errorCode").asString());
         // No eviction: 507 is not retryable, so it carries no Retry-After.
-        assertFalse(overCap.getHeaders().containsKey("Retry-After"));
+        assertFalse(overCap.getHeaders().containsHeader("Retry-After"));
     }
 
     private ResponseEntity<String> csv(String path, String body) {