diff --git a/CHANGELOG.md b/CHANGELOG.md
index 18bef3f..cf26215 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -48,4 +48,14 @@
 
 ### Notes
 - If you previously consumed `0.1.1`, update to `0.1.2` to pick up the dependency fix. Dependency metadata for `0.1.1` may be cached by your build; a version bump ensures the fix is resolved.
+## 0.1.3 — 2025-09-13
+
+### Enhancements
+- Add structured logging via Lombok `@Slf4j` in core components.
+  - Logs config resolution source (ENV, system property, file) and file load location.
+  - Logs HTTP requests (method, URI, timeout) and responses (status), with safe truncation and redaction.
+- Improve configuration discovery in fat jars/containers: try TCCL first, then class loader; support JVM system properties.
+
+### Notes
+- Enable debug logs with `logging.level.xyz.tcheeric=DEBUG` to see detailed request and configuration traces.
 
diff --git a/phoenixd-base/pom.xml b/phoenixd-base/pom.xml
index 9945008..aed2dfd 100644
--- a/phoenixd-base/pom.xml
+++ b/phoenixd-base/pom.xml
@@ -4,7 +4,7 @@
     <parent>
         <groupId>xyz.tcheeric</groupId>
         <artifactId>phoenixd-java</artifactId>
-        <version>0.1.2</version>
+        <version>0.1.3</version>
     </parent>
 
     <artifactId>phoenixd-base</artifactId>
@@ -18,6 +18,10 @@
     </properties>
 
     <dependencies>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
diff --git a/phoenixd-base/src/main/java/xyz/tcheeric/phoenixd/common/rest/util/Configuration.java b/phoenixd-base/src/main/java/xyz/tcheeric/phoenixd/common/rest/util/Configuration.java
index a860638..532bbc6 100644
--- a/phoenixd-base/src/main/java/xyz/tcheeric/phoenixd/common/rest/util/Configuration.java
+++ b/phoenixd-base/src/main/java/xyz/tcheeric/phoenixd/common/rest/util/Configuration.java
@@ -4,6 +4,7 @@
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 import lombok.SneakyThrows;
+import lombok.extern.slf4j.Slf4j;
 
 import java.io.InputStream;
 import java.net.URL;
@@ -13,6 +14,7 @@
 import java.util.Set;
 
 @RequiredArgsConstructor
+@Slf4j
 @Data
 public class Configuration {
 
@@ -30,10 +32,18 @@ private String envValue(@NonNull String key) {
 
     private String resolve(@NonNull String key) {
         String env = envValue(key);
-        if (env != null) return env;
+        if (env != null) {
+            if (log.isDebugEnabled()) log.debug("Config '{}' resolved from ENV", key);
+            return env;
+        }
         String sys = System.getProperty(prefix + "." + key);
-        if (sys != null && !sys.isEmpty()) return sys;
-        return properties.getProperty(prefix + "." + key);
+        if (sys != null && !sys.isEmpty()) {
+            if (log.isDebugEnabled()) log.debug("Config '{}' resolved from system properties", key);
+            return sys;
+        }
+        String fileVal = properties.getProperty(prefix + "." + key);
+        if (fileVal != null && log.isDebugEnabled()) log.debug("Config '{}' resolved from app.properties", key);
+        return fileVal;
     }
 
     @SneakyThrows
@@ -62,9 +72,13 @@ public Configuration(@NonNull String prefix) {
             try (InputStream in = resource.openStream()) {
                 if (in != null) {
                     this.properties.load(in);
+                    if (log.isInfoEnabled()) log.info("Loaded configuration from '{}'", resource);
                 }
             }
         }
+        if (properties.isEmpty()) {
+            log.warn("No app.properties found on classpath; relying on ENV and system properties only");
+        }
     }
 
     public List<String> keys() {
diff --git a/phoenixd-mock/pom.xml b/phoenixd-mock/pom.xml
index 6a23bfe..ff6adc3 100644
--- a/phoenixd-mock/pom.xml
+++ b/phoenixd-mock/pom.xml
@@ -6,7 +6,7 @@
     <parent>
         <groupId>xyz.tcheeric</groupId>
         <artifactId>phoenixd-java</artifactId>
-        <version>0.1.2</version>
+        <version>0.1.3</version>
     </parent>
 
     <artifactId>phoenixd-mock</artifactId>
diff --git a/phoenixd-model/pom.xml b/phoenixd-model/pom.xml
index 9a29a43..a1fa00e 100644
--- a/phoenixd-model/pom.xml
+++ b/phoenixd-model/pom.xml
@@ -4,7 +4,7 @@
     <parent>
         <groupId>xyz.tcheeric</groupId>
         <artifactId>phoenixd-java</artifactId>
-        <version>0.1.2</version>
+        <version>0.1.3</version>
     </parent>
 
     <artifactId>phoenixd-model</artifactId>
diff --git a/phoenixd-rest/pom.xml b/phoenixd-rest/pom.xml
index e549991..c852ee6 100644
--- a/phoenixd-rest/pom.xml
+++ b/phoenixd-rest/pom.xml
@@ -4,12 +4,12 @@
     <parent>
         <groupId>xyz.tcheeric</groupId>
         <artifactId>phoenixd-java</artifactId>
-        <version>0.1.2</version>
+        <version>0.1.3</version>
     </parent>
 
     <artifactId>phoenixd-rest</artifactId>
     <packaging>jar</packaging>
-    <version>0.1.2</version>
+    <version>0.1.3</version>
     <name>phoenixd-rest</name>
     <url>https://maven.apache.org</url>
 
@@ -18,6 +18,16 @@
     </properties>
 
     <dependencies>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>${slf4j.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+        </dependency>
         <dependency>
             <groupId>${project.groupId}</groupId>
             <artifactId>phoenixd-model</artifactId>
@@ -59,6 +69,16 @@
 
     <build>
         <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <configuration>
+                    <systemPropertyVariables>
+                        <org.slf4j.simpleLogger.defaultLogLevel>debug</org.slf4j.simpleLogger.defaultLogLevel>
+                        <org.slf4j.simpleLogger.log.xyz.tcheeric>debug</org.slf4j.simpleLogger.log.xyz.tcheeric>
+                    </systemPropertyVariables>
+                </configuration>
+            </plugin>
             <plugin>
                 <groupId>com.google.cloud.tools</groupId>
                 <artifactId>jib-maven-plugin</artifactId>
diff --git a/phoenixd-rest/src/main/java/xyz/tcheeric/phoenixd/operation/AbstractOperation.java b/phoenixd-rest/src/main/java/xyz/tcheeric/phoenixd/operation/AbstractOperation.java
index 8d5bdce..088136d 100644
--- a/phoenixd-rest/src/main/java/xyz/tcheeric/phoenixd/operation/AbstractOperation.java
+++ b/phoenixd-rest/src/main/java/xyz/tcheeric/phoenixd/operation/AbstractOperation.java
@@ -3,6 +3,7 @@
 import lombok.Data;
 import lombok.NonNull;
 import lombok.SneakyThrows;
+import lombok.extern.slf4j.Slf4j;
 import xyz.tcheeric.phoenixd.operation.impl.PostOperation;
 import xyz.tcheeric.phoenixd.common.rest.Operation;
 import xyz.tcheeric.phoenixd.common.rest.Request;
@@ -25,6 +26,7 @@
 import java.util.stream.Stream;
 
 @Data
+@Slf4j
 public abstract class AbstractOperation implements Operation {
 
     protected HttpRequest httpRequest;
@@ -46,6 +48,7 @@ private static long getLongProperty(String key, long defaultValue) {
 
     private static String ensureScheme(String baseUrl) {
         if (baseUrl == null || baseUrl.isBlank()) {
+            log.error("Missing required configuration 'phoenixd.base_url'");
             throw new IllegalArgumentException("phoenixd.base_url is not set");
         }
         String trimmed = baseUrl.trim();
@@ -53,6 +56,7 @@ private static String ensureScheme(String baseUrl) {
         if (lower.startsWith("http://") || lower.startsWith("https://")) {
             return trimmed;
         }
+        if (log.isDebugEnabled()) log.debug("No scheme in base_url '{}', defaulting to http://", baseUrl);
         return "http://" + trimmed;
     }
 
@@ -85,6 +89,9 @@ public AbstractOperation(@NonNull String method, @NonNull String path, String re
                 .timeout(Duration.ofMillis(timeout))
                 .method(method, bodyPublisher)
                 .build();
+        if (log.isDebugEnabled()) {
+            log.debug("Prepared HTTP request: method={}, uri={}, timeoutMs={}", method, this.httpRequest.uri(), timeout);
+        }
     }
 
     @SneakyThrows
@@ -112,19 +119,30 @@ public AbstractOperation(@NonNull String method, @NonNull String path, @NonNull
                 .timeout(Duration.ofMillis(timeout))
                 .method(method, bodyPublisher)
                 .build();
+        if (log.isDebugEnabled()) {
+            log.debug("Prepared HTTP request: method={}, uri={}, timeoutMs={} (with params)", method, this.httpRequest.uri(), timeout);
+        }
     }
 
     @SneakyThrows
     @Override
     public Operation execute() {
+        if (log.isDebugEnabled()) {
+            log.debug("Sending HTTP request: {} {}", httpRequest.method(), httpRequest.uri());
+        }
         CompletableFuture<HttpResponse<String>> response = HttpClient.newBuilder()
                 .build()
                 .sendAsync(httpRequest, HttpResponse.BodyHandlers.ofString());
         HttpResponse<String> httpResp = response.get();
         this.responseBody = httpResp.body();
         var statusCode = httpResp.statusCode();
+        if (log.isDebugEnabled()) {
+            log.debug("Received response: status={} uri={}", statusCode, httpRequest.uri());
+        }
         if (statusCode < 200 || statusCode >= 300) {
-            throw new IOException("Failed to create invoice: " + statusCode + " " + responseBody);
+            String preview = responseBody == null ? "" : (responseBody.length() > 512 ? responseBody.substring(0, 512) + "..." : responseBody);
+            log.error("HTTP request failed: status={} uri={} bodyPreview={}", statusCode, httpRequest.uri(), preview);
+            throw new IOException("Failed HTTP request: " + statusCode + " " + preview);
         }
         return this;
     }
@@ -154,6 +172,10 @@ public Operation addHeader(@NonNull String key, @NonNull String value) {
                 .build();
 
         this.setHttpRequest(newHttpRequest);
+        if (log.isDebugEnabled()) {
+            String safeVal = key.equalsIgnoreCase("Authorization") ? "<redacted>" : value;
+            log.debug("Updated header: {}={} for {} {}", key, safeVal, httpRequest.method(), httpRequest.uri());
+        }
 
         return this;
     }
@@ -185,6 +207,9 @@ public String replacePathVariables(String path, Request.Param param) {
                 throw new RuntimeException(e);
             }
         }
+        if (log.isDebugEnabled()) {
+            log.debug("Resolved path with variables: {}", path);
+        }
         return path;
     }
 }
diff --git a/phoenixd-rest/src/test/java/xyz/tcheeric/phoenixd/operation/BaseUrlMissingTest.java b/phoenixd-rest/src/test/java/xyz/tcheeric/phoenixd/operation/BaseUrlMissingTest.java
new file mode 100644
index 0000000..a1877fb
--- /dev/null
+++ b/phoenixd-rest/src/test/java/xyz/tcheeric/phoenixd/operation/BaseUrlMissingTest.java
@@ -0,0 +1,36 @@
+package xyz.tcheeric.phoenixd.operation;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+import xyz.tcheeric.phoenixd.operation.impl.PostOperation;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+class BaseUrlMissingTest {
+
+    @AfterEach
+    void cleanup() {
+        // Reset any system property override to avoid side effects on other tests
+        System.clearProperty("phoenixd.base_url");
+    }
+
+    // Ensures an explicit blank base_url triggers a clear configuration error
+    @Test
+    void blankBaseUrlThrows() {
+        System.setProperty("phoenixd.base_url", "   ");
+        assertThatThrownBy(() -> new PostOperation("/items", "data"))
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessageContaining("phoenixd.base_url is not set");
+    }
+
+    // Verifies path normalization when base_url has scheme but path lacks leading slash
+    @Test
+    void pathWithoutLeadingSlashIsNormalized() {
+        System.setProperty("phoenixd.base_url", "http://localhost:9740");
+        PostOperation op = new PostOperation("items", "data");
+        // URI should be http://localhost:9740/items (leading slash added)
+        org.assertj.core.api.Assertions.assertThat(op.getHttpRequest().uri().toString())
+                .isEqualTo("http://localhost:9740/items");
+    }
+}
+
diff --git a/phoenixd-test/pom.xml b/phoenixd-test/pom.xml
index d6db104..46d5b1e 100644
--- a/phoenixd-test/pom.xml
+++ b/phoenixd-test/pom.xml
@@ -4,7 +4,7 @@
     <parent>
         <groupId>xyz.tcheeric</groupId>
         <artifactId>phoenixd-java</artifactId>
-        <version>0.1.2</version>
+        <version>0.1.3</version>
     </parent>
 
     <artifactId>phoenixd-test</artifactId>
diff --git a/pom.xml b/pom.xml
index 86f0ac9..e67abc7 100644
--- a/pom.xml
+++ b/pom.xml
@@ -3,7 +3,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>xyz.tcheeric</groupId>
     <artifactId>phoenixd-java</artifactId>
-    <version>0.1.2</version>
+    <version>0.1.3</version>
     <packaging>pom</packaging>
 
     <modules>