Backport Skills API support fixes for 1.1.x branch

- Add missing ContentBlock.Type enum values for Skills responses:
  BASH_CODE_EXECUTION_TOOL_RESULT, TEXT_EDITOR_CODE_EXECUTION_TOOL_RESULT,
  SERVER_TOOL_USE
- Change ContentBlock.content field from String to Object to support
  complex nested structures in Skills responses
- Add ContentBlock.filename field for Skills-generated files
- Add contentAsString() convenience method with migration guidance
- Add serializeContent() helper in AnthropicChatModel
- Store anthropic-response in ChatResponseMetadata for
  SkillsResponseHelper to extract file IDs
- Update StreamHelper constructor calls for new ContentBlock signature
- Add Skills documentation to anthropic-chat.adoc

Signed-off-by: Soby Chacko <soby.chacko@broadcom.com>

Author: sobychacko

models/spring-ai-anthropic/src/main/java/org/springframework/ai/anthropic/AnthropicChatModel.java

@@ -381,7 +381,8 @@ private ChatResponse toChatResponse(ChatCompletionResponse chatCompletion, Usage
 			.usage(usage)
 			.keyValue("stop-reason", chatCompletion.stopReason())
 			.keyValue("stop-sequence", chatCompletion.stopSequence())
-			.keyValue("type", chatCompletion.type());
+			.keyValue("type", chatCompletion.type())
+			.keyValue("anthropic-response", chatCompletion);
 
 		// Add citation metadata if citations were found
 		if (citationContext.hasCitations()) {
@@ -711,11 +712,21 @@ else if (this.defaultOptions.getSkillContainer() != null) {
 		return request;
 	}
 
+	private static String serializeContent(Object content) {
+		if (content == null) {
+			return null;
+		}
+		if (content instanceof String s) {
+			return s;
+		}
+		return JsonParser.toJson(content);
+	}
+
 	private static ContentBlock cacheAwareContentBlock(ContentBlock contentBlock, MessageType messageType,
 			CacheEligibilityResolver cacheEligibilityResolver) {
 		String basisForLength = switch (contentBlock.type()) {
 			case TEXT, TEXT_DELTA -> contentBlock.text();
-			case TOOL_RESULT -> contentBlock.content();
+			case TOOL_RESULT -> serializeContent(contentBlock.content());
 			case TOOL_USE -> JsonParser.toJson(contentBlock.input());
 			case THINKING, THINKING_DELTA -> contentBlock.thinking();
 			case REDACTED_THINKING -> contentBlock.data();

models/spring-ai-anthropic/src/main/java/org/springframework/ai/anthropic/api/AnthropicApi.java

@@ -1155,7 +1155,7 @@ public record ContentBlock(
 
 		// tool_result response only
 		@JsonProperty("tool_use_id") String toolUseId,
-		@JsonProperty("content") String content,
+		@JsonProperty("content") Object content,
 
 		// Thinking only
 		@JsonProperty("signature") String signature,
@@ -1172,8 +1172,9 @@ public record ContentBlock(
 		@JsonProperty("context") String context,
 		@JsonProperty("citations") Object citations, // Can be CitationsConfig for requests or List<CitationResponse> for responses
 
-		// File content block from Skills
-		@JsonProperty("file_id") String fileId
+		// File fields (for Skills-generated files)
+		@JsonProperty("file_id") String fileId,
+		@JsonProperty("filename") String filename
 	) {
 		// @formatter:on
 
@@ -1192,7 +1193,7 @@ public ContentBlock(String mediaType, String data) {
 		 * @param source The source of the content.
 		 */
 		public ContentBlock(Type type, Source source) {
-			this(type, source, null, null, null, null, null, null, null, null, null, null, null, null, null, null,
+			this(type, source, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null,
 					null);
 		}
 
@@ -1202,7 +1203,7 @@ public ContentBlock(Type type, Source source) {
 		 */
 		public ContentBlock(Source source) {
 			this(Type.IMAGE, source, null, null, null, null, null, null, null, null, null, null, null, null, null, null,
-					null);
+					null, null);
 		}
 
 		/**
@@ -1211,12 +1212,12 @@ public ContentBlock(Source source) {
 		 */
 		public ContentBlock(String text) {
 			this(Type.TEXT, null, text, null, null, null, null, null, null, null, null, null, null, null, null, null,
-					null);
+					null, null);
 		}
 
 		public ContentBlock(String text, CacheControl cache) {
 			this(Type.TEXT, null, text, null, null, null, null, null, null, null, null, null, cache, null, null, null,
-					null);
+					null, null);
 		}
 
 		// Tool result
@@ -1228,7 +1229,7 @@ public ContentBlock(String text, CacheControl cache) {
 		 */
 		public ContentBlock(Type type, String toolUseId, String content) {
 			this(type, null, null, null, null, null, null, toolUseId, content, null, null, null, null, null, null, null,
-					null);
+					null, null);
 		}
 
 		/**
@@ -1240,7 +1241,7 @@ public ContentBlock(Type type, String toolUseId, String content) {
 		 */
 		public ContentBlock(Type type, Source source, String text, Integer index) {
 			this(type, source, text, index, null, null, null, null, null, null, null, null, null, null, null, null,
-					null);
+					null, null);
 		}
 
 		// Tool use input JSON delta streaming
@@ -1252,7 +1253,8 @@ public ContentBlock(Type type, Source source, String text, Integer index) {
 		 * @param input The input of the tool use.
 		 */
 		public ContentBlock(Type type, String id, String name, Map<String, Object> input) {
-			this(type, null, null, null, id, name, input, null, null, null, null, null, null, null, null, null, null);
+			this(type, null, null, null, id, name, input, null, null, null, null, null, null, null, null, null, null,
+					null);
 		}
 
 		/**
@@ -1266,13 +1268,26 @@ public ContentBlock(Type type, String id, String name, Map<String, Object> input
 		public ContentBlock(Source source, String title, String context, boolean citationsEnabled,
 				CacheControl cacheControl) {
 			this(Type.DOCUMENT, source, null, null, null, null, null, null, null, null, null, null, cacheControl, title,
-					context, citationsEnabled ? new CitationsConfig(true) : null, null);
+					context, citationsEnabled ? new CitationsConfig(true) : null, null, null);
 		}
 
 		public static ContentBlockBuilder from(ContentBlock contentBlock) {
 			return new ContentBlockBuilder(contentBlock);
 		}
 
+		/**
+		 * Returns the content as a String if it is a String, null otherwise.
+		 * <p>
+		 * Note: The {@link #content()} field was changed from {@code String} to
+		 * {@code Object} to support Skills responses which may return complex nested
+		 * structures. If you are using the low-level API and previously relied on
+		 * {@code content()} returning a String, use this method instead.
+		 * @return the content as String, or null if content is not a String
+		 */
+		public String contentAsString() {
+			return this.content instanceof String s ? s : null;
+		}
+
 		/**
 		 * The ContentBlock type.
 		 */
@@ -1349,10 +1364,35 @@ public enum Type {
 			REDACTED_THINKING("redacted_thinking"),
 
 			/**
-			 * File content block from Skills.
+			 * File content block representing a file generated by Skills. Used in
+			 * {@link org.springframework.ai.anthropic.SkillsResponseHelper} to extract
+			 * file IDs for downloading generated documents.
 			 */
 			@JsonProperty("file")
-			FILE("file");
+			FILE("file"),
+
+			/**
+			 * Bash code execution tool result returned in Skills responses. Observed in
+			 * actual API responses where file IDs are nested within this content block.
+			 * Required for JSON deserialization.
+			 */
+			@JsonProperty("bash_code_execution_tool_result")
+			BASH_CODE_EXECUTION_TOOL_RESULT("bash_code_execution_tool_result"),
+
+			/**
+			 * Text editor code execution tool result returned in Skills responses.
+			 * Observed in actual API responses. Required for JSON deserialization.
+			 */
+			@JsonProperty("text_editor_code_execution_tool_result")
+			TEXT_EDITOR_CODE_EXECUTION_TOOL_RESULT("text_editor_code_execution_tool_result"),
+
+			/**
+			 * Server-side tool use returned in Skills responses. Observed in actual API
+			 * responses when Skills invoke server-side tools. Required for JSON
+			 * deserialization.
+			 */
+			@JsonProperty("server_tool_use")
+			SERVER_TOOL_USE("server_tool_use");
 
 			public final String value;
 
@@ -1426,7 +1466,7 @@ public static class ContentBlockBuilder {
 
 			private String toolUseId;
 
-			private String content;
+			private Object content;
 
 			private String signature;
 
@@ -1444,6 +1484,8 @@ public static class ContentBlockBuilder {
 
 			private String fileId;
 
+			private String filename;
+
 			public ContentBlockBuilder(ContentBlock contentBlock) {
 				this.type = contentBlock.type;
 				this.source = contentBlock.source;
@@ -1462,6 +1504,7 @@ public ContentBlockBuilder(ContentBlock contentBlock) {
 				this.context = contentBlock.context;
 				this.citations = contentBlock.citations;
 				this.fileId = contentBlock.fileId;
+				this.filename = contentBlock.filename;
 			}
 
 			public ContentBlockBuilder type(Type type) {
@@ -1504,7 +1547,7 @@ public ContentBlockBuilder toolUseId(String toolUseId) {
 				return this;
 			}
 
-			public ContentBlockBuilder content(String content) {
+			public ContentBlockBuilder content(Object content) {
 				this.content = content;
 				return this;
 			}
@@ -1534,10 +1577,15 @@ public ContentBlockBuilder fileId(String fileId) {
 				return this;
 			}
 
+			public ContentBlockBuilder filename(String filename) {
+				this.filename = filename;
+				return this;
+			}
+
 			public ContentBlock build() {
 				return new ContentBlock(this.type, this.source, this.text, this.index, this.id, this.name, this.input,
 						this.toolUseId, this.content, this.signature, this.thinking, this.data, this.cacheControl,
-						this.title, this.context, this.citations, this.fileId);
+						this.title, this.context, this.citations, this.fileId, this.filename);
 			}
 
 		}

models/spring-ai-anthropic/src/main/java/org/springframework/ai/anthropic/api/StreamHelper.java

@@ -165,7 +165,7 @@ else if (event.type().equals(EventType.CONTENT_BLOCK_START)) {
 			else if (contentBlockStartEvent.contentBlock() instanceof ContentBlockThinking thinkingBlock) {
 				ContentBlock cb = new ContentBlock(Type.THINKING, null, null, contentBlockStartEvent.index(), null,
 						null, null, null, null, thinkingBlock.signature(), thinkingBlock.thinking(), null, null, null,
-						null, null, null);
+						null, null, null, null);
 				contentBlockReference.get().withType(event.type().name()).withContent(List.of(cb));
 			}
 			else {
@@ -182,12 +182,13 @@ else if (event.type().equals(EventType.CONTENT_BLOCK_DELTA)) {
 			}
 			else if (contentBlockDeltaEvent.delta() instanceof ContentBlockDeltaThinking thinking) {
 				ContentBlock cb = new ContentBlock(Type.THINKING_DELTA, null, null, contentBlockDeltaEvent.index(),
-						null, null, null, null, null, null, thinking.thinking(), null, null, null, null, null, null);
+						null, null, null, null, null, null, thinking.thinking(), null, null, null, null, null, null,
+						null);
 				contentBlockReference.get().withType(event.type().name()).withContent(List.of(cb));
 			}
 			else if (contentBlockDeltaEvent.delta() instanceof ContentBlockDeltaSignature sig) {
 				ContentBlock cb = new ContentBlock(Type.SIGNATURE_DELTA, null, null, contentBlockDeltaEvent.index(),
-						null, null, null, null, null, sig.signature(), null, null, null, null, null, null, null);
+						null, null, null, null, null, sig.signature(), null, null, null, null, null, null, null, null);
 				contentBlockReference.get().withType(event.type().name()).withContent(List.of(cb));
 			}
 			else {