api(apps): GET /apps/{slug}/dirty-state returns desired-vs-deployed diff

Wires DirtyStateCalculator behind an HTTP endpoint on AppController.
Adds findLatestSuccessfulByAppAndEnv to PostgresDeploymentRepository,
registers DirtyStateCalculator as a Spring bean (with ObjectMapper for
JavaTimeModule support), and covers all three scenarios with IT.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/rules/app-classes.md

@@ -53,7 +53,7 @@ Env-scoped read-path controllers (`AlertController`, `AlertRuleController`, `Ale
 
 ### Env-scoped (user-facing data & config)
 
-- `AppController` — `/api/v1/environments/{envSlug}/apps`. GET list / POST create / GET `{appSlug}` / DELETE `{appSlug}` / GET `{appSlug}/versions` / POST `{appSlug}/versions` (JAR upload) / PUT `{appSlug}/container-config`. App slug uniqueness is per-env (`(env, app_slug)` is the natural key). `CreateAppRequest` body has no env (path), validates slug regex.
+- `AppController` — `/api/v1/environments/{envSlug}/apps`. GET list / POST create / GET `{appSlug}` / DELETE `{appSlug}` / GET `{appSlug}/versions` / POST `{appSlug}/versions` (JAR upload) / PUT `{appSlug}/container-config` / GET `{appSlug}/dirty-state` (returns `DirtyStateResponse{dirty, lastSuccessfulDeploymentId, differences}` — compares current JAR+config against last RUNNING deployment snapshot; dirty=true when no snapshot exists). App slug uniqueness is per-env (`(env, app_slug)` is the natural key). `CreateAppRequest` body has no env (path), validates slug regex. Injects `DirtyStateCalculator` bean (registered in `RuntimeBeanConfig`, requires `ObjectMapper` with `JavaTimeModule`).
 - `DeploymentController` — `/api/v1/environments/{envSlug}/apps/{appSlug}/deployments`. GET list / POST create (body `{ appVersionId }`) / POST `{id}/stop` / POST `{id}/promote` (body `{ targetEnvironment: slug }` — target app slug must exist in target env) / GET `{id}/logs`.
 - `ApplicationConfigController` — `/api/v1/environments/{envSlug}`. GET `/config` (list), GET/PUT `/apps/{appSlug}/config`, GET `/apps/{appSlug}/processor-routes`, POST `/apps/{appSlug}/config/test-expression`. PUT also pushes `CONFIG_UPDATE` to LIVE agents in this env.
 - `AppSettingsController` — `/api/v1/environments/{envSlug}`. GET `/app-settings` (list), GET/PUT/DELETE `/apps/{appSlug}/settings`. ADMIN/OPERATOR only.

cameleer-server-app/src/main/java/com/cameleer/server/app/config/RuntimeBeanConfig.java

@@ -9,6 +9,7 @@ import com.cameleer.server.core.runtime.AppService;
 import com.cameleer.server.core.runtime.AppVersionRepository;
 import com.cameleer.server.core.runtime.DeploymentRepository;
 import com.cameleer.server.core.runtime.DeploymentService;
+import com.cameleer.server.core.runtime.DirtyStateCalculator;
 import com.cameleer.server.core.runtime.EnvironmentRepository;
 import com.cameleer.server.core.runtime.EnvironmentService;
 import com.fasterxml.jackson.databind.ObjectMapper;
@@ -64,6 +65,11 @@ public class RuntimeBeanConfig {
         return new DeploymentService(deployRepo, appService, envService);
     }
 
+    @Bean
+    public DirtyStateCalculator dirtyStateCalculator(ObjectMapper objectMapper) {
+        return new DirtyStateCalculator(objectMapper);
+    }
+
     @Bean(name = "deploymentTaskExecutor")
     public Executor deploymentTaskExecutor() {
         ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();

cameleer-server-app/src/main/java/com/cameleer/server/app/controller/AppController.java

@@ -1,14 +1,24 @@
 package com.cameleer.server.app.controller;
 
+import com.cameleer.common.model.ApplicationConfig;
+import com.cameleer.server.app.dto.DirtyStateResponse;
+import com.cameleer.server.app.storage.PostgresApplicationConfigRepository;
+import com.cameleer.server.app.storage.PostgresDeploymentRepository;
 import com.cameleer.server.app.web.EnvPath;
 import com.cameleer.server.core.runtime.App;
 import com.cameleer.server.core.runtime.AppService;
 import com.cameleer.server.core.runtime.AppVersion;
+import com.cameleer.server.core.runtime.AppVersionRepository;
+import com.cameleer.server.core.runtime.Deployment;
+import com.cameleer.server.core.runtime.DeploymentConfigSnapshot;
+import com.cameleer.server.core.runtime.DirtyStateCalculator;
+import com.cameleer.server.core.runtime.DirtyStateResult;
 import com.cameleer.server.core.runtime.Environment;
 import com.cameleer.server.core.runtime.RuntimeType;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.responses.ApiResponse;
 import io.swagger.v3.oas.annotations.tags.Tag;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.security.access.prepost.PreAuthorize;
@@ -22,8 +32,10 @@ import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.multipart.MultipartFile;
+import org.springframework.web.server.ResponseStatusException;
 
 import java.io.IOException;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 import java.util.UUID;
@@ -40,9 +52,21 @@ import java.util.UUID;
 public class AppController {
 
     private final AppService appService;
+    private final AppVersionRepository appVersionRepository;
+    private final PostgresApplicationConfigRepository configRepository;
+    private final PostgresDeploymentRepository deploymentRepository;
+    private final DirtyStateCalculator dirtyCalc;
 
-    public AppController(AppService appService) {
+    public AppController(AppService appService,
+                         AppVersionRepository appVersionRepository,
+                         PostgresApplicationConfigRepository configRepository,
+                         PostgresDeploymentRepository deploymentRepository,
+                         DirtyStateCalculator dirtyCalc) {
         this.appService = appService;
+        this.appVersionRepository = appVersionRepository;
+        this.configRepository = configRepository;
+        this.deploymentRepository = deploymentRepository;
+        this.dirtyCalc = dirtyCalc;
     }
 
     @GetMapping
@@ -120,6 +144,47 @@ public class AppController {
         }
     }
 
+    @GetMapping("/{appSlug}/dirty-state")
+    @Operation(summary = "Check whether the app's current config differs from the last successful deploy",
+            description = "Returns dirty=true when the desired state (current JAR + agent config + container config) "
+                    + "would produce a changed deployment. When no successful deploy exists yet, dirty=true.")
+    @ApiResponse(responseCode = "200", description = "Dirty-state computed")
+    @ApiResponse(responseCode = "404", description = "App not found in this environment")
+    public ResponseEntity<DirtyStateResponse> getDirtyState(@EnvPath Environment env,
+                                                             @PathVariable String appSlug) {
+        App app;
+        try {
+            app = appService.getByEnvironmentAndSlug(env.id(), appSlug);
+        } catch (IllegalArgumentException e) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND, "App not found");
+        }
+
+        // Latest JAR version (newest first — findByAppId orders by version DESC)
+        List<AppVersion> versions = appVersionRepository.findByAppId(app.id());
+        UUID latestVersionId = versions.isEmpty() ? null
+                : versions.stream().max(Comparator.comparingInt(AppVersion::version))
+                          .map(AppVersion::id).orElse(null);
+
+        // Desired agent config
+        ApplicationConfig agentConfig = configRepository
+                .findByApplicationAndEnvironment(appSlug, env.slug())
+                .orElse(null);
+
+        // Container config
+        Map<String, Object> containerConfig = app.containerConfig();
+
+        // Last successful deployment snapshot
+        Deployment lastSuccessful = deploymentRepository
+                .findLatestSuccessfulByAppAndEnv(app.id(), env.id())
+                .orElse(null);
+        DeploymentConfigSnapshot snapshot = lastSuccessful != null ? lastSuccessful.deployedConfigSnapshot() : null;
+
+        DirtyStateResult result = dirtyCalc.compute(latestVersionId, agentConfig, containerConfig, snapshot);
+
+        String lastId = lastSuccessful != null ? lastSuccessful.id().toString() : null;
+        return ResponseEntity.ok(new DirtyStateResponse(result.dirty(), lastId, result.differences()));
+    }
+
     private static final java.util.regex.Pattern CUSTOM_ARGS_PATTERN =
             java.util.regex.Pattern.compile("^[-a-zA-Z0-9_.=:/\\s+\"']*$");
 

cameleer-server-app/src/main/java/com/cameleer/server/app/dto/DirtyStateResponse.java

@@ -0,0 +1,12 @@
+package com.cameleer.server.app.dto;
+
+import com.cameleer.server.core.runtime.DirtyStateResult;
+
+import java.util.List;
+
+public record DirtyStateResponse(
+        boolean dirty,
+        String lastSuccessfulDeploymentId,
+        List<DirtyStateResult.Difference> differences
+) {
+}

cameleer-server-app/src/main/java/com/cameleer/server/app/storage/PostgresDeploymentRepository.java

@@ -139,6 +139,16 @@ public class PostgresDeploymentRepository implements DeploymentRepository {
         }
     }
 
+    public Optional<Deployment> findLatestSuccessfulByAppAndEnv(UUID appId, UUID envId) {
+        var results = jdbc.query(
+                "SELECT " + SELECT_COLS + " FROM deployments "
+                + "WHERE app_id = ? AND environment_id = ? "
+                + "AND status = 'RUNNING' AND deployed_config_snapshot IS NOT NULL "
+                + "ORDER BY deployed_at DESC NULLS LAST LIMIT 1",
+                (rs, rowNum) -> mapRow(rs), appId, envId);
+        return results.isEmpty() ? Optional.empty() : Optional.of(results.get(0));
+    }
+
     public Optional<Deployment> findByContainerId(String containerId) {
         var results = jdbc.query(
                 "SELECT " + SELECT_COLS + " FROM deployments WHERE replica_states::text LIKE ? " +

cameleer-server-app/src/test/java/com/cameleer/server/app/controller/AppDirtyStateIT.java

@@ -0,0 +1,235 @@
+package com.cameleer.server.app.controller;
+
+import com.cameleer.server.app.AbstractPostgresIT;
+import com.cameleer.server.app.TestSecurityHelper;
+import com.cameleer.server.app.dto.DirtyStateResponse;
+import com.cameleer.server.app.storage.PostgresDeploymentRepository;
+import com.cameleer.server.core.runtime.ContainerStatus;
+import com.cameleer.server.core.runtime.Deployment;
+import com.cameleer.server.core.runtime.DeploymentStatus;
+import com.cameleer.server.core.runtime.RuntimeOrchestrator;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.core.io.ByteArrayResource;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.MediaType;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.awaitility.Awaitility.await;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.when;
+
+/**
+ * Integration tests for GET /api/v1/environments/{envSlug}/apps/{appSlug}/dirty-state.
+ *
+ * <p>Uses @MockBean RuntimeOrchestrator (same pattern as DeploymentSnapshotIT).
+ * @DirtiesContext prevents context cache conflicts when both IT classes are loaded together.</p>
+ */
+@DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_CLASS)
+class AppDirtyStateIT extends AbstractPostgresIT {
+
+    @MockBean
+    RuntimeOrchestrator runtimeOrchestrator;
+
+    @Autowired
+    private TestRestTemplate restTemplate;
+
+    @Autowired
+    private ObjectMapper objectMapper;
+
+    @Autowired
+    private TestSecurityHelper securityHelper;
+
+    @Autowired
+    private PostgresDeploymentRepository deploymentRepository;
+
+    private String operatorJwt;
+
+    @BeforeEach
+    void setUp() {
+        operatorJwt = securityHelper.operatorToken();
+        jdbcTemplate.update("DELETE FROM deployments");
+        jdbcTemplate.update("DELETE FROM app_versions");
+        jdbcTemplate.update("DELETE FROM apps");
+        jdbcTemplate.update("DELETE FROM application_config WHERE environment = 'default'");
+    }
+
+    // -----------------------------------------------------------------------
+    // Test 1: no deployment ever → dirty=true, lastSuccessfulDeploymentId=null
+    // -----------------------------------------------------------------------
+
+    @Test
+    void dirtyState_noDeployEver_returnsDirtyTrue() throws Exception {
+        String appSlug = "ds-nodeploy-" + UUID.randomUUID().toString().substring(0, 8);
+        post("/api/v1/environments/default/apps",
+                String.format("{\"slug\": \"%s\", \"displayName\": \"DS No Deploy\"}", appSlug),
+                operatorJwt);
+        uploadJar(appSlug, ("fake-jar-" + appSlug).getBytes());
+        put("/api/v1/environments/default/apps/" + appSlug + "/config",
+                "{\"samplingRate\": 0.5}", operatorJwt);
+
+        DirtyStateResponse body = getDirtyState("default", appSlug);
+
+        assertThat(body.dirty()).isTrue();
+        assertThat(body.lastSuccessfulDeploymentId()).isNull();
+    }
+
+    // -----------------------------------------------------------------------
+    // Test 2: after a successful deploy with matching desired state → dirty=false
+    // -----------------------------------------------------------------------
+
+    @Test
+    void dirtyState_afterSuccessfulDeploy_matchingDesiredState_returnsDirtyFalse() throws Exception {
+        String fakeContainerId = "fake-cid-" + UUID.randomUUID();
+        when(runtimeOrchestrator.isEnabled()).thenReturn(true);
+        when(runtimeOrchestrator.startContainer(any())).thenReturn(fakeContainerId);
+        when(runtimeOrchestrator.getContainerStatus(fakeContainerId))
+                .thenReturn(new ContainerStatus("healthy", true, 0, null));
+
+        String appSlug = "ds-clean-" + UUID.randomUUID().toString().substring(0, 8);
+        post("/api/v1/environments/default/apps",
+                String.format("{\"slug\": \"%s\", \"displayName\": \"DS Clean\"}", appSlug),
+                operatorJwt);
+        put("/api/v1/environments/default/apps/" + appSlug + "/container-config",
+                "{\"runtimeType\": \"spring-boot\", \"appPort\": 8081}", operatorJwt);
+        String versionId = uploadJar(appSlug, ("fake-jar-clean-" + appSlug).getBytes());
+        put("/api/v1/environments/default/apps/" + appSlug + "/config",
+                "{\"samplingRate\": 0.25}", operatorJwt);
+
+        // Deploy and wait for RUNNING
+        JsonNode deploy = post(
+                "/api/v1/environments/default/apps/" + appSlug + "/deployments",
+                String.format("{\"appVersionId\": \"%s\"}", versionId),
+                operatorJwt);
+        String deploymentId = deploy.path("id").asText();
+
+        await().atMost(30, TimeUnit.SECONDS).pollInterval(500, TimeUnit.MILLISECONDS)
+                .untilAsserted(() -> {
+                    Deployment d = deploymentRepository.findById(UUID.fromString(deploymentId))
+                            .orElseThrow(() -> new AssertionError("Deployment not found"));
+                    assertThat(d.status()).isEqualTo(DeploymentStatus.RUNNING);
+                });
+
+        // Desired state matches what was deployed → dirty=false
+        DirtyStateResponse body = getDirtyState("default", appSlug);
+
+        assertThat(body.dirty()).isFalse();
+        assertThat(body.differences()).isEmpty();
+        assertThat(body.lastSuccessfulDeploymentId()).isEqualTo(deploymentId);
+    }
+
+    // -----------------------------------------------------------------------
+    // Test 3: after successful deploy, config changed → dirty=true
+    // -----------------------------------------------------------------------
+
+    @Test
+    void dirtyState_afterSuccessfulDeploy_configChanged_returnsDirtyTrue() throws Exception {
+        String fakeContainerId = "fake-cid2-" + UUID.randomUUID();
+        when(runtimeOrchestrator.isEnabled()).thenReturn(true);
+        when(runtimeOrchestrator.startContainer(any())).thenReturn(fakeContainerId);
+        when(runtimeOrchestrator.getContainerStatus(fakeContainerId))
+                .thenReturn(new ContainerStatus("healthy", true, 0, null));
+
+        String appSlug = "ds-dirty-" + UUID.randomUUID().toString().substring(0, 8);
+        post("/api/v1/environments/default/apps",
+                String.format("{\"slug\": \"%s\", \"displayName\": \"DS Dirty\"}", appSlug),
+                operatorJwt);
+        put("/api/v1/environments/default/apps/" + appSlug + "/container-config",
+                "{\"runtimeType\": \"spring-boot\", \"appPort\": 8081}", operatorJwt);
+        String versionId = uploadJar(appSlug, ("fake-jar-dirty-" + appSlug).getBytes());
+        put("/api/v1/environments/default/apps/" + appSlug + "/config",
+                "{\"samplingRate\": 0.1}", operatorJwt);
+
+        // Deploy and wait for RUNNING
+        JsonNode deploy = post(
+                "/api/v1/environments/default/apps/" + appSlug + "/deployments",
+                String.format("{\"appVersionId\": \"%s\"}", versionId),
+                operatorJwt);
+        String deploymentId = deploy.path("id").asText();
+
+        await().atMost(30, TimeUnit.SECONDS).pollInterval(500, TimeUnit.MILLISECONDS)
+                .untilAsserted(() -> {
+                    Deployment d = deploymentRepository.findById(UUID.fromString(deploymentId))
+                            .orElseThrow(() -> new AssertionError("Deployment not found"));
+                    assertThat(d.status()).isEqualTo(DeploymentStatus.RUNNING);
+                });
+
+        // Change samplingRate after deploy
+        put("/api/v1/environments/default/apps/" + appSlug + "/config",
+                "{\"samplingRate\": 0.9}", operatorJwt);
+
+        // Now desired state differs from snapshot → dirty=true
+        DirtyStateResponse body = getDirtyState("default", appSlug);
+
+        assertThat(body.dirty()).isTrue();
+        assertThat(body.lastSuccessfulDeploymentId()).isEqualTo(deploymentId);
+        assertThat(body.differences()).isNotEmpty();
+        assertThat(body.differences())
+                .anyMatch(d -> d.field().contains("samplingRate"));
+    }
+
+    // -----------------------------------------------------------------------
+    // Helpers
+    // -----------------------------------------------------------------------
+
+    private DirtyStateResponse getDirtyState(String envSlug, String appSlug) {
+        HttpHeaders headers = securityHelper.authHeaders(operatorJwt);
+        var response = restTemplate.exchange(
+                "/api/v1/environments/" + envSlug + "/apps/" + appSlug + "/dirty-state",
+                HttpMethod.GET,
+                new HttpEntity<>(headers),
+                DirtyStateResponse.class);
+        assertThat(response.getStatusCode().value()).isEqualTo(200);
+        return response.getBody();
+    }
+
+    private JsonNode post(String path, String json, String jwt) throws Exception {
+        HttpHeaders headers = securityHelper.authHeaders(jwt);
+        var response = restTemplate.exchange(
+                path, HttpMethod.POST,
+                new HttpEntity<>(json, headers),
+                String.class);
+        return objectMapper.readTree(response.getBody());
+    }
+
+    private void put(String path, String json, String jwt) {
+        HttpHeaders headers = securityHelper.authHeaders(jwt);
+        restTemplate.exchange(path, HttpMethod.PUT, new HttpEntity<>(json, headers), String.class);
+    }
+
+    private String uploadJar(String appSlug, byte[] content) throws Exception {
+        ByteArrayResource resource = new ByteArrayResource(content) {
+            @Override
+            public String getFilename() { return "app.jar"; }
+        };
+        MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
+        body.add("file", resource);
+
+        HttpHeaders headers = new HttpHeaders();
+        headers.set("Authorization", "Bearer " + operatorJwt);
+        headers.set("X-Cameleer-Protocol-Version", "1");
+        headers.setContentType(MediaType.MULTIPART_FORM_DATA);
+
+        var response = restTemplate.exchange(
+                "/api/v1/environments/default/apps/" + appSlug + "/versions",
+                HttpMethod.POST,
+                new HttpEntity<>(body, headers),
+                String.class);
+
+        JsonNode versionNode = objectMapper.readTree(response.getBody());
+        return versionNode.path("id").asText();
+    }
+}

cameleer-server-core/src/main/java/com/cameleer/server/core/runtime/DirtyStateCalculator.java

@@ -16,11 +16,17 @@ import java.util.UUID;
  * Compares the app's current desired state (JAR + agent config + container config) to the
  * config snapshot from the last successful deployment, producing a structured dirty result.
  *
- * <p>Pure logic — no IO, no Spring. Safe to unit-test as a POJO.</p>
+ * <p>Pure logic — no IO, no Spring. Safe to unit-test as a POJO.
+ * Caller must supply an {@link ObjectMapper} configured with {@code JavaTimeModule} so that
+ * {@code ApplicationConfig.updatedAt} (an {@link java.time.Instant}) serialises correctly.</p>
  */
 public class DirtyStateCalculator {
 
-    private static final ObjectMapper MAPPER = new ObjectMapper();
+    private final ObjectMapper mapper;
+
+    public DirtyStateCalculator(ObjectMapper mapper) {
+        this.mapper = mapper;
+    }
 
     public DirtyStateResult compute(UUID desiredJarVersionId,
                                     ApplicationConfig desiredAgentConfig,
@@ -38,10 +44,10 @@ public class DirtyStateCalculator {
                     String.valueOf(desiredJarVersionId), String.valueOf(snapshot.jarVersionId())));
         }
 
-        compareJson("agentConfig", MAPPER.valueToTree(desiredAgentConfig),
-                MAPPER.valueToTree(snapshot.agentConfig()), diffs);
-        compareJson("containerConfig", MAPPER.valueToTree(desiredContainerConfig),
-                MAPPER.valueToTree(snapshot.containerConfig()), diffs);
+        compareJson("agentConfig", mapper.valueToTree(desiredAgentConfig),
+                mapper.valueToTree(snapshot.agentConfig()), diffs);
+        compareJson("containerConfig", mapper.valueToTree(desiredContainerConfig),
+                mapper.valueToTree(snapshot.containerConfig()), diffs);
 
         return new DirtyStateResult(!diffs.isEmpty(), diffs);
     }

cameleer-server-core/src/test/java/com/cameleer/server/core/runtime/DirtyStateCalculatorTest.java

@@ -1,6 +1,7 @@
 package com.cameleer.server.core.runtime;
 
 import com.cameleer.common.model.ApplicationConfig;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import org.junit.jupiter.api.Test;
 
 import java.util.Map;
@@ -10,9 +11,11 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 class DirtyStateCalculatorTest {
 
+    private static final DirtyStateCalculator CALC = new DirtyStateCalculator(new ObjectMapper());
+
     @Test
     void noSnapshot_meansEverythingDirty() {
-        DirtyStateCalculator calc = new DirtyStateCalculator();
+        DirtyStateCalculator calc = CALC;
 
         ApplicationConfig desiredAgent = new ApplicationConfig();
         desiredAgent.setSamplingRate(1.0);
@@ -27,7 +30,7 @@ class DirtyStateCalculatorTest {
 
     @Test
     void identicalSnapshot_isClean() {
-        DirtyStateCalculator calc = new DirtyStateCalculator();
+        DirtyStateCalculator calc = CALC;
 
         ApplicationConfig cfg = new ApplicationConfig();
         cfg.setSamplingRate(0.5);
@@ -43,7 +46,7 @@ class DirtyStateCalculatorTest {
 
     @Test
     void differentJar_marksJarField() {
-        DirtyStateCalculator calc = new DirtyStateCalculator();
+        DirtyStateCalculator calc = CALC;
         ApplicationConfig cfg = new ApplicationConfig();
         Map<String, Object> container = Map.of();
         UUID v1 = UUID.randomUUID();
@@ -59,7 +62,7 @@ class DirtyStateCalculatorTest {
 
     @Test
     void differentSamplingRate_marksAgentField() {
-        DirtyStateCalculator calc = new DirtyStateCalculator();
+        DirtyStateCalculator calc = CALC;
 
         ApplicationConfig deployedCfg = new ApplicationConfig();
         deployedCfg.setSamplingRate(0.5);
@@ -77,7 +80,7 @@ class DirtyStateCalculatorTest {
 
     @Test
     void differentContainerMemory_marksContainerField() {
-        DirtyStateCalculator calc = new DirtyStateCalculator();
+        DirtyStateCalculator calc = CALC;
         ApplicationConfig cfg = new ApplicationConfig();
         UUID jarId = UUID.randomUUID();
         DeploymentConfigSnapshot snap = new DeploymentConfigSnapshot(jarId, cfg, Map.of("memoryLimitMb", 512));
@@ -91,7 +94,7 @@ class DirtyStateCalculatorTest {
 
     @Test
     void nullAgentConfigInSnapshot_marksAgentConfigDiff() {
-        DirtyStateCalculator calc = new DirtyStateCalculator();
+        DirtyStateCalculator calc = CALC;
         ApplicationConfig desired = new ApplicationConfig();
         desired.setSamplingRate(1.0);
         UUID jarId = UUID.randomUUID();
@@ -106,7 +109,7 @@ class DirtyStateCalculatorTest {
 
     @Test
     void nestedAgentField_reportsDeepPath() {
-        DirtyStateCalculator calc = new DirtyStateCalculator();
+        DirtyStateCalculator calc = CALC;
 
         ApplicationConfig deployed = new ApplicationConfig();
         deployed.setTracedProcessors(Map.of("proc-1", "DEBUG"));
@@ -124,7 +127,7 @@ class DirtyStateCalculatorTest {
 
     @Test
     void stringField_differenceValueIsUnquoted() {
-        DirtyStateCalculator calc = new DirtyStateCalculator();
+        DirtyStateCalculator calc = CALC;
 
         ApplicationConfig deployed = new ApplicationConfig();
         deployed.setApplicationLogLevel("INFO");