fix: normalize missing args for stdio MCP connections (closes #39)

base/src/main/java/ai/javaclaw/mcp/McpStdioArgsNormalizerApplicationContextInitializer.java

@@ -0,0 +1,59 @@
+package ai.javaclaw.mcp;
+
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.core.Ordered;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.env.EnumerablePropertySource;
+import org.springframework.core.env.MapPropertySource;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Normalizes stdio MCP connection properties by ensuring an `args` list exists
+ * when a stdio connection is declared. Implemented as an
+ * ApplicationContextInitializer to avoid deprecated APIs.
+ */
+public class McpStdioArgsNormalizerApplicationContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext>, Ordered {
+
+    private static final String PREFIX = "spring.ai.mcp.client.stdio.connections.";
+
+    @Override
+    public void initialize(ConfigurableApplicationContext context) {
+        ConfigurableEnvironment environment = context.getEnvironment();
+        Map<String, Object> additions = new HashMap<>();
+
+        Set<String> names = new java.util.HashSet<>();
+        for (org.springframework.core.env.PropertySource<?> ps : environment.getPropertySources()) {
+            if (ps instanceof EnumerablePropertySource<?> eps) {
+                for (String propName : eps.getPropertyNames()) {
+                    if (propName.startsWith(PREFIX)) {
+                        String remainder = propName.substring(PREFIX.length());
+                        int idx = remainder.indexOf('.');
+                        String name = idx > 0 ? remainder.substring(0, idx) : remainder;
+                        names.add(name);
+                    }
+                }
+            }
+        }
+
+        for (String name : names) {
+            String cmdKey = PREFIX + name + ".command";
+            String argsKey = PREFIX + name + ".args";
+            if (environment.containsProperty(cmdKey) && !environment.containsProperty(argsKey)) {
+                additions.put(argsKey, java.util.List.of());
+            }
+        }
+
+        if (!additions.isEmpty()) {
+            environment.getPropertySources().addFirst(new MapPropertySource("mcpStdioArgsNormalizer", additions));
+        }
+    }
+
+    @Override
+    public int getOrder() {
+        return Ordered.HIGHEST_PRECEDENCE + 20;
+    }
+}

base/src/main/resources/META-INF/spring.factories

@@ -0,0 +1,2 @@
+org.springframework.context.ApplicationContextInitializer=\
+ai.javaclaw.mcp.McpStdioArgsNormalizerApplicationContextInitializer

base/src/test/java/ai/javaclaw/mcp/McpStdioArgsNormalizerApplicationContextInitializerTest.java

@@ -0,0 +1,61 @@
+package ai.javaclaw.mcp;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.context.support.GenericApplicationContext;
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.StandardEnvironment;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class McpStdioArgsNormalizerApplicationContextInitializerTest {
+
+    @Test
+    void addsEmptyArgsWhenCommandPresentAndArgsMissing() {
+        StandardEnvironment env = new StandardEnvironment();
+        MapPropertySource src = new MapPropertySource("test", Map.of(
+                "spring.ai.mcp.client.stdio.connections.foo.command", "dummy-cmd"
+        ));
+        env.getPropertySources().addFirst(src);
+
+        GenericApplicationContext ctx = new GenericApplicationContext();
+        ctx.setEnvironment(env);
+
+        McpStdioArgsNormalizerApplicationContextInitializer init = new McpStdioArgsNormalizerApplicationContextInitializer();
+        init.initialize(ctx);
+
+        String argsKey = "spring.ai.mcp.client.stdio.connections.foo.args";
+
+        assertNotNull(env.getPropertySources().get("mcpStdioArgsNormalizer"), "expected normalizer property source to exist");
+
+        Object raw = env.getPropertySources().get("mcpStdioArgsNormalizer").getProperty(argsKey);
+        assertNotNull(raw, "expected args property to be present in the normalizer property source");
+        assertTrue(raw instanceof List, "expected raw args value to be a List");
+        assertTrue(((List<?>) raw).isEmpty(), "expected args list to be empty");
+    }
+
+    @Test
+    void doesNotOverwriteExistingArgs() {
+        StandardEnvironment env = new StandardEnvironment();
+        MapPropertySource src = new MapPropertySource("test", Map.of(
+                "spring.ai.mcp.client.stdio.connections.bar.command", "cmd",
+                "spring.ai.mcp.client.stdio.connections.bar.args", List.of("a")
+        ));
+        env.getPropertySources().addFirst(src);
+
+        GenericApplicationContext ctx = new GenericApplicationContext();
+        ctx.setEnvironment(env);
+
+        McpStdioArgsNormalizerApplicationContextInitializer init = new McpStdioArgsNormalizerApplicationContextInitializer();
+        init.initialize(ctx);
+
+        assertNull(env.getPropertySources().get("mcpStdioArgsNormalizer"), "expected normalizer property source to be absent when no additions were required");
+
+        Object raw = env.getPropertySources().get("test").getProperty("spring.ai.mcp.client.stdio.connections.bar.args");
+        assertNotNull(raw);
+        assertTrue(raw instanceof List);
+        assertEquals(1, ((List<?>) raw).size());
+    }
+}

base/src/test/java/ai/javaclaw/mcp/McpStdioArgsNormalizerApplicationContextRunnerTest.java

@@ -0,0 +1,30 @@
+package ai.javaclaw.mcp;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class McpStdioArgsNormalizerApplicationContextRunnerTest {
+
+    /**
+     * Verifies that {@code StdioTransportAutoConfiguration} does not throw
+     * {@code "The args can not be null"} when a stdio MCP connection is declared
+     * without an explicit args list — the normalizer must inject an empty list before
+     * autoconfiguration runs.
+     */
+    @Test
+    void contextDoesNotFailWhenArgsMissingAndNormalizerPresent() {
+        ApplicationContextRunner runner = new ApplicationContextRunner()
+                .withInitializer(new McpStdioArgsNormalizerApplicationContextInitializer())
+                .withPropertyValues("spring.ai.mcp.client.stdio.connections.foo.command=dummy-cmd")
+                .withConfiguration(AutoConfigurations.of(
+                        org.springframework.ai.mcp.client.common.autoconfigure.StdioTransportAutoConfiguration.class
+                ));
+
+        runner.run(context -> {
+            assertNull(context.getStartupFailure(), "expected context to start without startup failure");
+        });
+    }
+}