From e6e74676f4c15489f9f360bbedcac75a0f2f8f7c Mon Sep 17 00:00:00 2001
From: "M. Emin Cihangeri" <m.emin.cihangeri@sap.com>
Date: Thu, 25 Jun 2026 15:51:58 +0200
Subject: [PATCH 01/49] fix: Auto-route tool call results to messages_history

---
 ...hestration-completion-post-request.test.ts | 58 ++++++++++++
 .../orchestration/src/util/module-config.ts   | 36 +++++---
 sample-code/src/index.ts                      |  4 +-
 sample-code/src/orchestration.ts              | 88 ++++++++++++++++++-
 tests/e2e-tests/src/orchestration.test.ts     | 17 +++-
 5 files changed, 189 insertions(+), 14 deletions(-)

diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index 3019ad68a..3c63f2fbb 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -337,4 +337,62 @@ describe('construct completion post request', () => {
       );
     expect(completionPostRequest).toEqual(expectedCompletionPostRequest);
   });
+
+  describe('tool message auto-routing', () => {
+    const toolCallId = 'call_abc123';
+    const assistantMessage = {
+      role: 'assistant' as const,
+      tool_calls: [
+        {
+          id: toolCallId,
+          type: 'function' as const,
+          function: { name: 'search', arguments: '{"query":"test"}' }
+        }
+      ]
+    };
+    const toolMessage = {
+      role: 'tool' as const,
+      content: 'Result: {{?question}}',
+      tool_call_id: toolCallId
+    };
+    const userMessage = { role: 'user' as const, content: 'Summarize.' };
+
+    it('should route tool messages from messages to messages_history', () => {
+      const result = constructCompletionPostRequest(defaultConfig, {
+        messages: [userMessage, toolMessage]
+      });
+
+      expect(result.messages_history).toEqual([userMessage, toolMessage]);
+      expect(
+        (result.config.modules as any).prompt_templating.prompt.template
+      ).not.toContainEqual(toolMessage);
+      expect(
+        (result.config.modules as any).prompt_templating.prompt.template
+      ).not.toContainEqual(userMessage);
+    });
+
+    it('should preserve existing messagesHistory when appending tool messages', () => {
+      const result = constructCompletionPostRequest(defaultConfig, {
+        messages: [userMessage, toolMessage],
+        messagesHistory: [assistantMessage]
+      });
+
+      expect(result.messages_history).toEqual([
+        assistantMessage,
+        userMessage,
+        toolMessage
+      ]);
+    });
+
+    it('should not affect non-tool messages', () => {
+      const result = constructCompletionPostRequest(defaultConfig, {
+        messages: [userMessage]
+      });
+
+      expect(result.messages_history).toBeUndefined();
+      expect(
+        (result.config.modules as any).prompt_templating.prompt.template
+      ).toContainEqual(userMessage);
+    });
+  });
 });
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 75e508241..3047258e8 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -358,16 +358,31 @@ export function constructCompletionPostRequest(
   // - Single config (OrchestrationModuleConfig) → single ModuleConfigs object
   // - Config array (OrchestrationModuleConfigList) → array of ModuleConfigs for fallback behavior
 
-  // When any config uses a TemplateRef, messages cannot be merged into prompt.template
-  // (the template lives remotely). Route them to messages_history instead.
+  // Determine where to split request.messages: everything before splitIndex is routed
+  // to messages_history (bypassing prompt templating); everything from splitIndex onward
+  // stays in messages and is merged into prompt.template.
+  //
+  // Two cases route messages out of templating:
+  // 1. TemplateRef configs — the template lives remotely, so messages cannot be merged in.
+  // 2. Tool results — their content comes from external systems and may contain {{?...}}
+  //    patterns that are not user-defined placeholders. We route through the last tool
+  //    message so the assistant+tool pair stays together for tool_call_id validation.
   const configs = Array.isArray(config) ? config : [config];
-  const routeMessagesToHistory = configs.some(c =>
+  const usesTemplateRef = configs.some(c =>
     isTemplateRef(c?.promptTemplating?.prompt || {})
   );
+  const messages = request?.messages || [];
+  const lastToolIndex = messages.reduce(
+    (last, msg, i) => (msg.role === 'tool' ? i : last),
+    -1
+  );
+  const splitIndex = usesTemplateRef
+    ? messages.length
+    : lastToolIndex + 1;
 
   const moduleRequest =
-    routeMessagesToHistory && request
-      ? { ...request, messages: undefined }
+    splitIndex > 0 && request
+      ? { ...request, messages: messages.slice(splitIndex) }
       : request;
 
   /**
@@ -389,18 +404,17 @@ export function constructCompletionPostRequest(
         )
     : { modules: moduleConfigurations };
 
-  // When routing messages to history, append request.messages after messagesHistory
-  const messagesHistory =
-    routeMessagesToHistory && request?.messages?.length
-      ? [...(request.messagesHistory || []), ...request.messages]
-      : request?.messagesHistory;
+  const messagesHistory = [
+    ...(request?.messagesHistory || []),
+    ...messages.slice(0, splitIndex)
+  ];
 
   return {
     config: configWithStream,
     ...(request?.placeholderValues && {
       placeholder_values: request.placeholderValues
     }),
-    ...(messagesHistory && {
+    ...(messagesHistory.length && {
       messages_history: messagesHistory
     })
   };
diff --git a/sample-code/src/index.ts b/sample-code/src/index.ts
index 072dc1d39..57c1bb165 100644
--- a/sample-code/src/index.ts
+++ b/sample-code/src/index.ts
@@ -35,7 +35,9 @@ export {
   orchestrationWithFallbackConfigs,
   orchestrationSonarWithCitations,
   orchestrationSonarStreamWithCitations,
-  orchestrationStreamWithFallbackConfigs
+  orchestrationStreamWithFallbackConfigs,
+  orchestrationToolResultInMessages,
+  orchestrationToolResultMaskingInMessagesHistory
 } from './orchestration.js';
 export {
   invoke,
diff --git a/sample-code/src/orchestration.ts b/sample-code/src/orchestration.ts
index 4849f7ce8..991f1f779 100644
--- a/sample-code/src/orchestration.ts
+++ b/sample-code/src/orchestration.ts
@@ -22,7 +22,8 @@ import type {
   OrchestrationErrorResponse,
   ChatCompletionTool,
   ToolChatMessage,
-  PromptTemplatingModule
+  PromptTemplatingModule,
+  AssistantChatMessage
 } from '@sap-ai-sdk/orchestration';
 
 const logger = createLogger({
@@ -777,6 +778,91 @@ export async function orchestrationMessageHistoryWithToolCalling(): Promise<Orch
   });
 }
 
+/**
+ * Verify that tool results containing {{?...}} syntax in messages are automatically
+ * routed to messages_history by the SDK, bypassing prompt templating.
+ */
+export async function orchestrationToolResultInMessages(): Promise<OrchestrationResponse> {
+  const client = new OrchestrationClient({
+    promptTemplating: {
+      model: { name: 'anthropic--claude-4.5-haiku' },
+      prompt: { template: [{ role: 'system', content: 'You are helpful.' }] }
+    }
+  });
+
+  const assistantMessage: AssistantChatMessage = {
+    role: 'assistant',
+    tool_calls: [
+      {
+        id: 'call_abc123',
+        type: 'function',
+        function: { name: 'search', arguments: '{"query":"test"}' }
+      }
+    ]
+  };
+
+  const toolMessage: ToolChatMessage = {
+    role: 'tool',
+    // Simulates a tool result from an external system that happens to contain
+    // prompt templating syntax — the SDK must route this to messages_history.
+    content: 'Search result: the user asked {{?question}}',
+    tool_call_id: 'call_abc123'
+  };
+
+  return client.chatCompletion({
+    messages: [
+      assistantMessage,
+      toolMessage,
+      { role: 'user', content: 'Summarize the tool output.' }
+    ]
+  });
+}
+
+/**
+ * Verify whether masking is applied to tool results automatically routed to messages_history.
+ * This confirms that auto-routing does not bypass anonymisation.
+ */
+export async function orchestrationToolResultMaskingInMessagesHistory(): Promise<OrchestrationResponse> {
+  const client = new OrchestrationClient({
+    promptTemplating: {
+      model: { name: 'anthropic--claude-4.5-haiku' }
+    },
+    masking: {
+      masking_providers: [
+        buildDpiMaskingProvider({
+          method: 'pseudonymization',
+          entities: ['profile-email']
+        })
+      ]
+    }
+  });
+
+  const assistantMessage: AssistantChatMessage = {
+    role: 'assistant',
+    tool_calls: [
+      {
+        id: 'call_abc123',
+        type: 'function',
+        function: { name: 'fetch_customer', arguments: '{"id":"42"}' }
+      }
+    ]
+  };
+
+  const toolMessage: ToolChatMessage = {
+    role: 'tool',
+    content: 'Customer email is john.doe@example.com',
+    tool_call_id: 'call_abc123'
+  };
+
+  return client.chatCompletion({
+    messages: [
+      assistantMessage,
+      toolMessage,
+      { role: 'user', content: 'Summarize the customer data.' }
+    ]
+  });
+}
+
 /**
  * Use translation module for input and output translation with advanced features.
  * @returns The orchestration service response.
diff --git a/tests/e2e-tests/src/orchestration.test.ts b/tests/e2e-tests/src/orchestration.test.ts
index 42e29380e..0cb6ba2b3 100644
--- a/tests/e2e-tests/src/orchestration.test.ts
+++ b/tests/e2e-tests/src/orchestration.test.ts
@@ -24,7 +24,9 @@ import {
   orchestrationWithFallbackConfigs,
   orchestrationSonarWithCitations,
   orchestrationSonarStreamWithCitations,
-  orchestrationStreamWithFallbackConfigs
+  orchestrationStreamWithFallbackConfigs,
+  orchestrationToolResultInMessages,
+  orchestrationToolResultMaskingInMessagesHistory
 } from '@sap-ai-sdk/sample-code';
 import {
   OrchestrationClient,
@@ -332,4 +334,17 @@ describe('orchestration', () => {
       expect(Array.isArray(citations)).toBe(true);
     }
   });
+
+  describe('tool result prompt templating interference', () => {
+    it('should succeed when tool result containing {{?...}} syntax is sent via messages', async () => {
+      const response = await orchestrationToolResultInMessages();
+      expect(response.getContent()).toEqual(expect.any(String));
+    });
+
+    it('should apply masking to tool results automatically routed to messages_history', async () => {
+      const response = await orchestrationToolResultMaskingInMessagesHistory();
+      expect(response.getIntermediateResults().input_masking).toBeDefined();
+      expect(response.getContent()).toEqual(expect.any(String));
+    });
+  });
 });

From 02e73cb337e0312ef0540ce968b6f31e91e92346 Mon Sep 17 00:00:00 2001
From: "M. Emin Cihangeri" <m.emin.cihangeri@sap.com>
Date: Thu, 25 Jun 2026 16:00:10 +0200
Subject: [PATCH 02/49] chore: Fix lint

---
 packages/orchestration/src/util/module-config.ts | 4 +---
 sample-code/src/orchestration.ts                 | 2 ++
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 3047258e8..b96593d83 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -376,9 +376,7 @@ export function constructCompletionPostRequest(
     (last, msg, i) => (msg.role === 'tool' ? i : last),
     -1
   );
-  const splitIndex = usesTemplateRef
-    ? messages.length
-    : lastToolIndex + 1;
+  const splitIndex = usesTemplateRef ? messages.length : lastToolIndex + 1;
 
   const moduleRequest =
     splitIndex > 0 && request
diff --git a/sample-code/src/orchestration.ts b/sample-code/src/orchestration.ts
index 991f1f779..bc60f7d37 100644
--- a/sample-code/src/orchestration.ts
+++ b/sample-code/src/orchestration.ts
@@ -781,6 +781,7 @@ export async function orchestrationMessageHistoryWithToolCalling(): Promise<Orch
 /**
  * Verify that tool results containing {{?...}} syntax in messages are automatically
  * routed to messages_history by the SDK, bypassing prompt templating.
+ * @returns The orchestration service response.
  */
 export async function orchestrationToolResultInMessages(): Promise<OrchestrationResponse> {
   const client = new OrchestrationClient({
@@ -821,6 +822,7 @@ export async function orchestrationToolResultInMessages(): Promise<Orchestration
 /**
  * Verify whether masking is applied to tool results automatically routed to messages_history.
  * This confirms that auto-routing does not bypass anonymisation.
+ * @returns The orchestration service response.
  */
 export async function orchestrationToolResultMaskingInMessagesHistory(): Promise<OrchestrationResponse> {
   const client = new OrchestrationClient({

From 0170e97c694b349328dea806c5a137dd5768f2fc Mon Sep 17 00:00:00 2001
From: emincihangeri <76652821+emincihangeri@users.noreply.github.com>
Date: Mon, 29 Jun 2026 14:10:52 +0200
Subject: [PATCH 03/49] Update packages/orchestration/src/util/module-config.ts

Co-authored-by: David Knaack <david.knaack@sap.com>
---
 packages/orchestration/src/util/module-config.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index b96593d83..7cf2ec115 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -412,7 +412,7 @@ export function constructCompletionPostRequest(
     ...(request?.placeholderValues && {
       placeholder_values: request.placeholderValues
     }),
-    ...(messagesHistory.length && {
+    ...((request?.messagesHistory || messagesHistory.length) && {
       messages_history: messagesHistory
     })
   };

From 977206118031ddc6c71253a42f6c05e19fd10a62 Mon Sep 17 00:00:00 2001
From: "M. Emin Cihangeri" <m.emin.cihangeri@sap.com>
Date: Mon, 29 Jun 2026 14:23:31 +0200
Subject: [PATCH 04/49] chore: Add changeset

---
 .changeset/yummy-ducks-run.md                          |  5 +++++
 .../src/orchestration-completion-post-request.test.ts  | 10 +++++-----
 2 files changed, 10 insertions(+), 5 deletions(-)
 create mode 100644 .changeset/yummy-ducks-run.md

diff --git a/.changeset/yummy-ducks-run.md b/.changeset/yummy-ducks-run.md
new file mode 100644
index 000000000..c7df2f6ac
--- /dev/null
+++ b/.changeset/yummy-ducks-run.md
@@ -0,0 +1,5 @@
+---
+'@sap-ai-sdk/orchestration': patch
+---
+
+[Fix] Route `role: "tool"` messages from `messages` to `messages_history` automatically.
diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index 3c63f2fbb..b2238bac9 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -358,16 +358,16 @@ describe('construct completion post request', () => {
     const userMessage = { role: 'user' as const, content: 'Summarize.' };
 
     it('should route tool messages from messages to messages_history', () => {
-      const result = constructCompletionPostRequest(defaultConfig, {
+      const result: any = constructCompletionPostRequest(defaultConfig, {
         messages: [userMessage, toolMessage]
       });
 
       expect(result.messages_history).toEqual([userMessage, toolMessage]);
       expect(
-        (result.config.modules as any).prompt_templating.prompt.template
+        result.config.modules.prompt_templating.prompt.template
       ).not.toContainEqual(toolMessage);
       expect(
-        (result.config.modules as any).prompt_templating.prompt.template
+        result.config.modules.prompt_templating.prompt.template
       ).not.toContainEqual(userMessage);
     });
 
@@ -385,13 +385,13 @@ describe('construct completion post request', () => {
     });
 
     it('should not affect non-tool messages', () => {
-      const result = constructCompletionPostRequest(defaultConfig, {
+      const result: any = constructCompletionPostRequest(defaultConfig, {
         messages: [userMessage]
       });
 
       expect(result.messages_history).toBeUndefined();
       expect(
-        (result.config.modules as any).prompt_templating.prompt.template
+        result.config.modules.prompt_templating.prompt.template
       ).toContainEqual(userMessage);
     });
   });

From ba033a713850a5bd9e83a14ba0548e7038c9c996 Mon Sep 17 00:00:00 2001
From: "M. Emin Cihangeri" <m.emin.cihangeri@sap.com>
Date: Mon, 29 Jun 2026 14:36:27 +0200
Subject: [PATCH 05/49] chore: Enable ES2023 array methods in tsconfig

---
 packages/orchestration/src/util/module-config.ts | 5 +----
 tsconfig.json                                    | 1 +
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 7cf2ec115..da3f3a4ad 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -372,10 +372,7 @@ export function constructCompletionPostRequest(
     isTemplateRef(c?.promptTemplating?.prompt || {})
   );
   const messages = request?.messages || [];
-  const lastToolIndex = messages.reduce(
-    (last, msg, i) => (msg.role === 'tool' ? i : last),
-    -1
-  );
+  const lastToolIndex = messages.findLastIndex(msg => msg.role === 'tool');
   const splitIndex = usesTemplateRef ? messages.length : lastToolIndex + 1;
 
   const moduleRequest =
diff --git a/tsconfig.json b/tsconfig.json
index 42dfb4a53..44fc7a776 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,6 +1,7 @@
 {
   "compilerOptions": {
     "target": "ES2022",
+    "lib": ["es2023", "dom"],
     "module": "Node16",
     "declaration": true,
     "declarationMap": true,

From b733f83320a6f56757fc97dd3105ece0966e216e Mon Sep 17 00:00:00 2001
From: emincihangeri <76652821+emincihangeri@users.noreply.github.com>
Date: Mon, 29 Jun 2026 15:57:42 +0200
Subject: [PATCH 06/49] Update tsconfig.json

Co-authored-by: David Knaack <david.knaack@sap.com>
---
 tsconfig.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tsconfig.json b/tsconfig.json
index 44fc7a776..e472afeeb 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "target": "ES2022",
-    "lib": ["es2023", "dom"],
+    "lib": ["es2023"],
     "module": "Node16",
     "declaration": true,
     "declarationMap": true,

From 06831ae8ca9e7b36abe2bc947f482173e14135ce Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Tue, 30 Jun 2026 16:22:40 +0200
Subject: [PATCH 07/49] fix: address review comments and add message order
 tests

---
 ...hestration-completion-post-request.test.ts | 30 +++++++++++++++++++
 .../orchestration/src/orchestration-types.ts  |  5 ++++
 .../orchestration/src/util/module-config.ts   | 22 ++++++++------
 .../src/tutorials/mcp/weather-mcp-server.ts   |  4 ++-
 tests/e2e-tests/src/orchestration.test.ts     | 14 +++++++++
 5 files changed, 65 insertions(+), 10 deletions(-)

diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index b2238bac9..0c79cf360 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -394,5 +394,35 @@ describe('construct completion post request', () => {
         result.config.modules.prompt_templating.prompt.template
       ).toContainEqual(userMessage);
     });
+
+    it('should preserve chronological message order across the split', () => {
+      const followUpUser = { role: 'user' as const, content: 'Follow up.' };
+      const result: any = constructCompletionPostRequest(defaultConfig, {
+        messages: [userMessage, assistantMessage, toolMessage, followUpUser]
+      });
+
+      // messages before and including last tool go to messages_history in order
+      expect(result.messages_history).toEqual([
+        userMessage,
+        assistantMessage,
+        toolMessage
+      ]);
+      // only messages after the last tool stay in prompt.template
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).toContainEqual(followUpUser);
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).not.toContainEqual(toolMessage);
+    });
+
+    it('should emit messages_history when only messagesHistory is provided (no tool messages)', () => {
+      const result = constructCompletionPostRequest(defaultConfig, {
+        messages: [userMessage],
+        messagesHistory: [assistantMessage]
+      });
+
+      expect(result.messages_history).toEqual([assistantMessage]);
+    });
   });
 });
diff --git a/packages/orchestration/src/orchestration-types.ts b/packages/orchestration/src/orchestration-types.ts
index 4a3b73007..f9fa55d62 100644
--- a/packages/orchestration/src/orchestration-types.ts
+++ b/packages/orchestration/src/orchestration-types.ts
@@ -43,6 +43,11 @@ export interface ChatCompletionRequest {
 
   /**
    * New chat messages, including template messages.
+   * Messages with `role: 'tool'` — and all messages preceding them — are automatically
+   * routed to `messages_history` to bypass prompt templating. This prevents tool results
+   * from external systems containing `{{?...}}` syntax from being misinterpreted as
+   * template placeholders. To verify the final message order sent to the LLM, use
+   * `response.getIntermediateResults().templating`.
    * @example
    * messages: [
    *   {
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index da3f3a4ad..5cbf37508 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -375,10 +375,14 @@ export function constructCompletionPostRequest(
   const lastToolIndex = messages.findLastIndex(msg => msg.role === 'tool');
   const splitIndex = usesTemplateRef ? messages.length : lastToolIndex + 1;
 
-  const moduleRequest =
-    splitIndex > 0 && request
-      ? { ...request, messages: messages.slice(splitIndex) }
-      : request;
+  const remainingMessages = messages.slice(splitIndex);
+  let moduleRequest = request;
+  if (splitIndex > 0 && request) {
+    moduleRequest = {
+      ...request,
+      messages: remainingMessages.length ? remainingMessages : undefined
+    };
+  }
 
   /**
    * Module configurations for the orchestration request.
@@ -399,17 +403,17 @@ export function constructCompletionPostRequest(
         )
     : { modules: moduleConfigurations };
 
-  const messagesHistory = [
-    ...(request?.messagesHistory || []),
-    ...messages.slice(0, splitIndex)
-  ];
+  const messagesHistory =
+    splitIndex > 0 || request?.messagesHistory?.length
+      ? [...(request?.messagesHistory || []), ...messages.slice(0, splitIndex)]
+      : undefined;
 
   return {
     config: configWithStream,
     ...(request?.placeholderValues && {
       placeholder_values: request.placeholderValues
     }),
-    ...((request?.messagesHistory || messagesHistory.length) && {
+    ...(messagesHistory && {
       messages_history: messagesHistory
     })
   };
diff --git a/sample-code/src/tutorials/mcp/weather-mcp-server.ts b/sample-code/src/tutorials/mcp/weather-mcp-server.ts
index 632afd91d..7449ca064 100644
--- a/sample-code/src/tutorials/mcp/weather-mcp-server.ts
+++ b/sample-code/src/tutorials/mcp/weather-mcp-server.ts
@@ -48,7 +48,9 @@ server.registerTool(
     try {
       const geoUrl = buildGeocodingUrl(city);
       const geoResponse = await fetch(geoUrl);
-      const data = await geoResponse.json();
+      const data = (await geoResponse.json()) as {
+        results?: { latitude: number; longitude: number }[];
+      };
 
       if (!data.results?.length) {
         return {
diff --git a/tests/e2e-tests/src/orchestration.test.ts b/tests/e2e-tests/src/orchestration.test.ts
index 0cb6ba2b3..96c8468ac 100644
--- a/tests/e2e-tests/src/orchestration.test.ts
+++ b/tests/e2e-tests/src/orchestration.test.ts
@@ -339,12 +339,26 @@ describe('orchestration', () => {
     it('should succeed when tool result containing {{?...}} syntax is sent via messages', async () => {
       const response = await orchestrationToolResultInMessages();
       expect(response.getContent()).toEqual(expect.any(String));
+
+      const templating = response.getIntermediateResults().templating;
+      expect(templating).toBeDefined();
+      const roles = templating!.map(m => m.role);
+      const toolIdx = roles.lastIndexOf('tool');
+      const userIdx = roles.lastIndexOf('user');
+      expect(toolIdx).toBeGreaterThan(-1);
+      expect(userIdx).toBeGreaterThan(toolIdx);
     });
 
     it('should apply masking to tool results automatically routed to messages_history', async () => {
       const response = await orchestrationToolResultMaskingInMessagesHistory();
       expect(response.getIntermediateResults().input_masking).toBeDefined();
       expect(response.getContent()).toEqual(expect.any(String));
+
+      const templating = response.getIntermediateResults().templating;
+      expect(templating).toBeDefined();
+      const roles = templating!.map(m => m.role);
+      expect(roles).toContain('tool');
+      expect(roles.lastIndexOf('user')).toBeGreaterThan(roles.lastIndexOf('tool'));
     });
   });
 });

From 889db2c4df6c4e27a2535e759245df36995675eb Mon Sep 17 00:00:00 2001
From: "sap-ai-sdk-bot[bot]"
 <272306433+sap-ai-sdk-bot[bot]@users.noreply.github.com>
Date: Tue, 30 Jun 2026 14:24:25 +0000
Subject: [PATCH 08/49] fix: Changes from lint

---
 tests/e2e-tests/src/orchestration.test.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tests/e2e-tests/src/orchestration.test.ts b/tests/e2e-tests/src/orchestration.test.ts
index 96c8468ac..84f3f8b7c 100644
--- a/tests/e2e-tests/src/orchestration.test.ts
+++ b/tests/e2e-tests/src/orchestration.test.ts
@@ -358,7 +358,9 @@ describe('orchestration', () => {
       expect(templating).toBeDefined();
       const roles = templating!.map(m => m.role);
       expect(roles).toContain('tool');
-      expect(roles.lastIndexOf('user')).toBeGreaterThan(roles.lastIndexOf('tool'));
+      expect(roles.lastIndexOf('user')).toBeGreaterThan(
+        roles.lastIndexOf('tool')
+      );
     });
   });
 });

From 00deb0ce9aad827c9a55cf43b8a6ade32f29ac9c Mon Sep 17 00:00:00 2001
From: Injun Park <injun.park@sap.com>
Date: Fri, 3 Jul 2026 14:35:07 +0200
Subject: [PATCH 09/49] Apply suggestions from code review

Co-authored-by: David Knaack <david.knaack@sap.com>
---
 .changeset/yummy-ducks-run.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.changeset/yummy-ducks-run.md b/.changeset/yummy-ducks-run.md
index c7df2f6ac..19f0c1007 100644
--- a/.changeset/yummy-ducks-run.md
+++ b/.changeset/yummy-ducks-run.md
@@ -2,4 +2,4 @@
 '@sap-ai-sdk/orchestration': patch
 ---
 
-[Fix] Route `role: "tool"` messages from `messages` to `messages_history` automatically.
+[Fix] Route messages preceding tool messages from the `promptTemplating` section `messages` property to `messages_history` automatically if  no templating placeholder values are provided.

From 7c91e686446e0a633882af4840b7173f5208896f Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Fri, 3 Jul 2026 14:41:58 +0200
Subject: [PATCH 10/49] apply feedbacks from david

---
 tests/e2e-tests/src/orchestration.test.ts | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/tests/e2e-tests/src/orchestration.test.ts b/tests/e2e-tests/src/orchestration.test.ts
index 84f3f8b7c..e569fa88e 100644
--- a/tests/e2e-tests/src/orchestration.test.ts
+++ b/tests/e2e-tests/src/orchestration.test.ts
@@ -341,12 +341,8 @@ describe('orchestration', () => {
       expect(response.getContent()).toEqual(expect.any(String));
 
       const templating = response.getIntermediateResults().templating;
-      expect(templating).toBeDefined();
       const roles = templating!.map(m => m.role);
-      const toolIdx = roles.lastIndexOf('tool');
-      const userIdx = roles.lastIndexOf('user');
-      expect(toolIdx).toBeGreaterThan(-1);
-      expect(userIdx).toBeGreaterThan(toolIdx);
+      expect(roles).toEqual(['assistant', 'tool', 'user']);
     });
 
     it('should apply masking to tool results automatically routed to messages_history', async () => {

From 1d872147afd1e3ba89e472aefa2224749bfb9656 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Mon, 6 Jul 2026 13:48:32 +0200
Subject: [PATCH 11/49] fix: disable auto-routing when static prompt template
 is present

- Skip tool-message auto-routing to messages_history when any config
  has a non-empty prompt.template (static template = user opted into
  templating, service handles it correctly without interference)
- Move lib: [es2023] from root tsconfig.json to packages/orchestration/tsconfig.json
  to resolve merge conflict with main's tsconfig restructuring
- Update unit tests to use a no-template config for auto-routing cases
  and add a test asserting auto-routing is disabled with static templates
- Remove static system prompt from orchestrationToolResultInMessages sample
  so auto-routing is actually exercised in e2e
---
 ...hestration-completion-post-request.test.ts | 38 +++++++++++++++----
 .../orchestration/src/util/module-config.ts   | 10 ++++-
 packages/orchestration/tsconfig.json          |  1 +
 sample-code/src/orchestration.ts              |  3 +-
 4 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index 0c79cf360..2acaa8d2e 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -357,12 +357,21 @@ describe('construct completion post request', () => {
     };
     const userMessage = { role: 'user' as const, content: 'Summarize.' };
 
+    // Config without a static template — auto-routing is active
+    const noTemplateConfig: OrchestrationModuleConfig = {
+      promptTemplating: {
+        model: { name: 'gpt-5.4-nano' },
+        prompt: { template: [] }
+      }
+    };
+
     it('should route tool messages from messages to messages_history', () => {
-      const result: any = constructCompletionPostRequest(defaultConfig, {
-        messages: [userMessage, toolMessage]
+      const result: any = constructCompletionPostRequest(noTemplateConfig, {
+        messages: [userMessage, toolMessage, { role: 'user' as const, content: 'Follow up.' }]
       });
 
-      expect(result.messages_history).toEqual([userMessage, toolMessage]);
+      expect(result.messages_history).toContainEqual(userMessage);
+      expect(result.messages_history).toContainEqual(toolMessage);
       expect(
         result.config.modules.prompt_templating.prompt.template
       ).not.toContainEqual(toolMessage);
@@ -372,8 +381,9 @@ describe('construct completion post request', () => {
     });
 
     it('should preserve existing messagesHistory when appending tool messages', () => {
-      const result = constructCompletionPostRequest(defaultConfig, {
-        messages: [userMessage, toolMessage],
+      const followUpUser = { role: 'user' as const, content: 'Follow up.' };
+      const result = constructCompletionPostRequest(noTemplateConfig, {
+        messages: [userMessage, toolMessage, followUpUser],
         messagesHistory: [assistantMessage]
       });
 
@@ -385,7 +395,7 @@ describe('construct completion post request', () => {
     });
 
     it('should not affect non-tool messages', () => {
-      const result: any = constructCompletionPostRequest(defaultConfig, {
+      const result: any = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage]
       });
 
@@ -397,7 +407,7 @@ describe('construct completion post request', () => {
 
     it('should preserve chronological message order across the split', () => {
       const followUpUser = { role: 'user' as const, content: 'Follow up.' };
-      const result: any = constructCompletionPostRequest(defaultConfig, {
+      const result: any = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage, assistantMessage, toolMessage, followUpUser]
       });
 
@@ -417,12 +427,24 @@ describe('construct completion post request', () => {
     });
 
     it('should emit messages_history when only messagesHistory is provided (no tool messages)', () => {
-      const result = constructCompletionPostRequest(defaultConfig, {
+      const result = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage],
         messagesHistory: [assistantMessage]
       });
 
       expect(result.messages_history).toEqual([assistantMessage]);
     });
+
+    it('should not auto-route when config has a static prompt template', () => {
+      // static template present → auto-routing disabled, tool message stays in prompt.template
+      const result: any = constructCompletionPostRequest(defaultConfig, {
+        messages: [assistantMessage, toolMessage, userMessage]
+      });
+
+      expect(result.messages_history).toBeUndefined();
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).toContainEqual(toolMessage);
+    });
   });
 });
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 5cbf37508..f86b1d65c 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -367,12 +367,20 @@ export function constructCompletionPostRequest(
   // 2. Tool results — their content comes from external systems and may contain {{?...}}
   //    patterns that are not user-defined placeholders. We route through the last tool
   //    message so the assistant+tool pair stays together for tool_call_id validation.
+  //    Auto-routing is skipped when any config has a non-empty prompt.template, because
+  //    in that case the user has opted into templating and the service handles it correctly.
   const configs = Array.isArray(config) ? config : [config];
   const usesTemplateRef = configs.some(c =>
     isTemplateRef(c?.promptTemplating?.prompt || {})
   );
+  const hasStaticTemplate = configs.some(c => {
+    const prompt = c?.promptTemplating?.prompt;
+    return isTemplate(prompt) && prompt.template?.length;
+  });
   const messages = request?.messages || [];
-  const lastToolIndex = messages.findLastIndex(msg => msg.role === 'tool');
+  const lastToolIndex = hasStaticTemplate
+    ? -1
+    : messages.findLastIndex(msg => msg.role === 'tool');
   const splitIndex = usesTemplateRef ? messages.length : lastToolIndex + 1;
 
   const remainingMessages = messages.slice(splitIndex);
diff --git a/packages/orchestration/tsconfig.json b/packages/orchestration/tsconfig.json
index 2caf7a3cc..8cd9f136e 100644
--- a/packages/orchestration/tsconfig.json
+++ b/packages/orchestration/tsconfig.json
@@ -1,6 +1,7 @@
 {
   "extends": "../../tsconfig.json",
   "compilerOptions": {
+    "lib": ["es2023"],
     "rootDir": "./src",
     "outDir": "./dist",
     "tsBuildInfoFile": "./dist/.tsbuildinfo",
diff --git a/sample-code/src/orchestration.ts b/sample-code/src/orchestration.ts
index bc60f7d37..180496a91 100644
--- a/sample-code/src/orchestration.ts
+++ b/sample-code/src/orchestration.ts
@@ -786,8 +786,7 @@ export async function orchestrationMessageHistoryWithToolCalling(): Promise<Orch
 export async function orchestrationToolResultInMessages(): Promise<OrchestrationResponse> {
   const client = new OrchestrationClient({
     promptTemplating: {
-      model: { name: 'anthropic--claude-4.5-haiku' },
-      prompt: { template: [{ role: 'system', content: 'You are helpful.' }] }
+      model: { name: 'anthropic--claude-4.5-haiku' }
     }
   });
 

From 3022bfd0dff278b07500652f84f0910576c6ed76 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Mon, 6 Jul 2026 14:46:52 +0200
Subject: [PATCH 12/49] fix: also disable auto-routing when prompt has tools
 but no template
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

prompt.tools (without template) still means the user opted into
orchestration's prompt handling — auto-routing tool messages to
messages_history in this case leaves messages empty and throws
'Either a prompt template or messages must be defined'.

Extend hasStaticPrompt check to cover prompt.tools so that
multi-turn tool-calling flows (orchestrationMessageHistoryWithToolCalling)
are not broken by the auto-routing logic.
---
 ...rchestration-completion-post-request.test.ts | 17 +++++++++++++++++
 .../orchestration/src/util/module-config.ts     | 10 +++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index 2acaa8d2e..9724e4d26 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -446,5 +446,22 @@ describe('construct completion post request', () => {
         result.config.modules.prompt_templating.prompt.template
       ).toContainEqual(toolMessage);
     });
+
+    it('should not auto-route when config has prompt.tools (no template)', () => {
+      const toolsConfig: OrchestrationModuleConfig = {
+        promptTemplating: {
+          model: { name: 'gpt-5.4-nano' },
+          prompt: { tools: [{ type: 'function', function: { name: 'search', description: 'search', parameters: {} } }] }
+        }
+      };
+      const result: any = constructCompletionPostRequest(toolsConfig, {
+        messages: [assistantMessage, toolMessage, userMessage]
+      });
+
+      expect(result.messages_history).toBeUndefined();
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).toContainEqual(toolMessage);
+    });
   });
 });
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index f86b1d65c..9e668ff16 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -367,18 +367,18 @@ export function constructCompletionPostRequest(
   // 2. Tool results — their content comes from external systems and may contain {{?...}}
   //    patterns that are not user-defined placeholders. We route through the last tool
   //    message so the assistant+tool pair stays together for tool_call_id validation.
-  //    Auto-routing is skipped when any config has a non-empty prompt.template, because
-  //    in that case the user has opted into templating and the service handles it correctly.
+  //    Auto-routing is skipped when any config has a non-empty prompt.template or prompt.tools,
+  //    because in that case the user has opted into templating and the service handles it correctly.
   const configs = Array.isArray(config) ? config : [config];
   const usesTemplateRef = configs.some(c =>
     isTemplateRef(c?.promptTemplating?.prompt || {})
   );
-  const hasStaticTemplate = configs.some(c => {
+  const hasStaticPrompt = configs.some(c => {
     const prompt = c?.promptTemplating?.prompt;
-    return isTemplate(prompt) && prompt.template?.length;
+    return isTemplate(prompt) && (prompt.template?.length || prompt.tools?.length);
   });
   const messages = request?.messages || [];
-  const lastToolIndex = hasStaticTemplate
+  const lastToolIndex = hasStaticPrompt
     ? -1
     : messages.findLastIndex(msg => msg.role === 'tool');
   const splitIndex = usesTemplateRef ? messages.length : lastToolIndex + 1;

From 937d6d28b104afbf33191d9460f2d6f574a77d82 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Mon, 6 Jul 2026 17:06:37 +0200
Subject: [PATCH 13/49] fix: extract split logic, skip routing when placeholder
 values are set

---
 .changeset/yummy-ducks-run.md                 |  2 +-
 .../orchestration/src/util/module-config.ts   | 69 ++++++++++++-------
 2 files changed, 46 insertions(+), 25 deletions(-)

diff --git a/.changeset/yummy-ducks-run.md b/.changeset/yummy-ducks-run.md
index 19f0c1007..0449b89d8 100644
--- a/.changeset/yummy-ducks-run.md
+++ b/.changeset/yummy-ducks-run.md
@@ -2,4 +2,4 @@
 '@sap-ai-sdk/orchestration': patch
 ---
 
-[Fix] Route messages preceding tool messages from the `promptTemplating` section `messages` property to `messages_history` automatically if  no templating placeholder values are provided.
+[Fix] Automatically route `role: 'tool'` messages (and all preceding messages) from `messages` to `messages_history` to bypass prompt templating, unless placeholder values are provided.
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 9e668ff16..180487f0f 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -11,6 +11,7 @@ import {
   type EmbeddingRequest
 } from '../orchestration-types.js';
 import type {
+  ChatMessage,
   CompletionPostRequest,
   CompletionRequestConfigurationReferenceById,
   CompletionRequestConfigurationReferenceByNameScenarioVersion,
@@ -358,37 +359,16 @@ export function constructCompletionPostRequest(
   // - Single config (OrchestrationModuleConfig) → single ModuleConfigs object
   // - Config array (OrchestrationModuleConfigList) → array of ModuleConfigs for fallback behavior
 
-  // Determine where to split request.messages: everything before splitIndex is routed
-  // to messages_history (bypassing prompt templating); everything from splitIndex onward
-  // stays in messages and is merged into prompt.template.
-  //
-  // Two cases route messages out of templating:
-  // 1. TemplateRef configs — the template lives remotely, so messages cannot be merged in.
-  // 2. Tool results — their content comes from external systems and may contain {{?...}}
-  //    patterns that are not user-defined placeholders. We route through the last tool
-  //    message so the assistant+tool pair stays together for tool_call_id validation.
-  //    Auto-routing is skipped when any config has a non-empty prompt.template or prompt.tools,
-  //    because in that case the user has opted into templating and the service handles it correctly.
   const configs = Array.isArray(config) ? config : [config];
-  const usesTemplateRef = configs.some(c =>
-    isTemplateRef(c?.promptTemplating?.prompt || {})
-  );
-  const hasStaticPrompt = configs.some(c => {
-    const prompt = c?.promptTemplating?.prompt;
-    return isTemplate(prompt) && (prompt.template?.length || prompt.tools?.length);
-  });
   const messages = request?.messages || [];
-  const lastToolIndex = hasStaticPrompt
-    ? -1
-    : messages.findLastIndex(msg => msg.role === 'tool');
-  const splitIndex = usesTemplateRef ? messages.length : lastToolIndex + 1;
+  const splitIndex = getMessageSplitIndex(configs, messages, request);
 
-  const remainingMessages = messages.slice(splitIndex);
   let moduleRequest = request;
   if (splitIndex > 0 && request) {
+    const remaining = messages.slice(splitIndex);
     moduleRequest = {
       ...request,
-      messages: remainingMessages.length ? remainingMessages : undefined
+      messages: remaining.length ? remaining : undefined
     };
   }
 
@@ -464,6 +444,47 @@ function buildCompletionModulesConfig(
   };
 }
 
+/**
+ * Determines the split index for routing messages to messages_history.
+ * Messages before splitIndex bypass prompt templating; messages from splitIndex onward
+ * stay in prompt.template.
+ *
+ * Routing is skipped when:
+ * - placeholder values are set (user has opted into templating)
+ * - any config has a non-empty static prompt.template or prompt.tools
+ *
+ * When a TemplateRef is used, all messages are routed (splitIndex = messages.length).
+ */
+function getMessageSplitIndex(
+  configs: OrchestrationModuleConfig[],
+  messages: ChatMessage[],
+  request?: ChatCompletionRequest
+): number {
+  const usesTemplateRef = configs.some(c =>
+    isTemplateRef(c?.promptTemplating?.prompt || {})
+  );
+  if (usesTemplateRef) {
+    return messages.length;
+  }
+
+  const hasPlaceholderValues =
+    !!request?.placeholderValues &&
+    Object.keys(request.placeholderValues).length > 0;
+  if (hasPlaceholderValues) {
+    return 0;
+  }
+
+  const hasStaticPrompt = configs.some(c => {
+    const prompt = c?.promptTemplating?.prompt;
+    return isTemplate(prompt) && (prompt.template?.length || prompt.tools?.length);
+  });
+  if (hasStaticPrompt) {
+    return 0;
+  }
+
+  return messages.findLastIndex(msg => msg.role === 'tool') + 1;
+}
+
 function isTemplate(templating: unknown): templating is Template {
   return (
     !!templating &&

From 8f49badf0f96d843a1202ac8c26bcfe716ac9f37 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Tue, 7 Jul 2026 10:52:08 +0200
Subject: [PATCH 14/49] fix: add missing JSDoc params to getMessageSplitIndex

---
 ...hestration-completion-post-request.test.ts | 19 +++++++++++++++++--
 .../orchestration/src/orchestration-types.ts  |  3 ++-
 .../orchestration/src/util/module-config.ts   | 10 ++++++++--
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index 9724e4d26..2e967fe07 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -367,7 +367,11 @@ describe('construct completion post request', () => {
 
     it('should route tool messages from messages to messages_history', () => {
       const result: any = constructCompletionPostRequest(noTemplateConfig, {
-        messages: [userMessage, toolMessage, { role: 'user' as const, content: 'Follow up.' }]
+        messages: [
+          userMessage,
+          toolMessage,
+          { role: 'user' as const, content: 'Follow up.' }
+        ]
       });
 
       expect(result.messages_history).toContainEqual(userMessage);
@@ -451,7 +455,18 @@ describe('construct completion post request', () => {
       const toolsConfig: OrchestrationModuleConfig = {
         promptTemplating: {
           model: { name: 'gpt-5.4-nano' },
-          prompt: { tools: [{ type: 'function', function: { name: 'search', description: 'search', parameters: {} } }] }
+          prompt: {
+            tools: [
+              {
+                type: 'function',
+                function: {
+                  name: 'search',
+                  description: 'search',
+                  parameters: {}
+                }
+              }
+            ]
+          }
         }
       };
       const result: any = constructCompletionPostRequest(toolsConfig, {
diff --git a/packages/orchestration/src/orchestration-types.ts b/packages/orchestration/src/orchestration-types.ts
index bf06e09a6..095f69419 100644
--- a/packages/orchestration/src/orchestration-types.ts
+++ b/packages/orchestration/src/orchestration-types.ts
@@ -681,7 +681,8 @@ export interface DocumentTranslationApplyToSelector {
  * Target language for translation, either a language code or a selector configuration.
  */
 export type TranslationTargetLanguage =
-  string | DocumentTranslationApplyToSelector;
+  | string
+  | DocumentTranslationApplyToSelector;
 
 /**
  * Input parameters for translation configuration.
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 180487f0f..143458d5e 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -451,9 +451,13 @@ function buildCompletionModulesConfig(
  *
  * Routing is skipped when:
  * - placeholder values are set (user has opted into templating)
- * - any config has a non-empty static prompt.template or prompt.tools
+ * - any config has a non-empty static prompt.template or prompt.tools.
  *
  * When a TemplateRef is used, all messages are routed (splitIndex = messages.length).
+ * @param configs - The orchestration module configurations.
+ * @param messages - The chat messages to evaluate.
+ * @param request - The optional chat completion request containing placeholder values.
+ * @returns The index at which to split messages between messages_history and prompt.template.
  */
 function getMessageSplitIndex(
   configs: OrchestrationModuleConfig[],
@@ -476,7 +480,9 @@ function getMessageSplitIndex(
 
   const hasStaticPrompt = configs.some(c => {
     const prompt = c?.promptTemplating?.prompt;
-    return isTemplate(prompt) && (prompt.template?.length || prompt.tools?.length);
+    return (
+      isTemplate(prompt) && (prompt.template?.length || prompt.tools?.length)
+    );
   });
   if (hasStaticPrompt) {
     return 0;

From e02c07d64cc854db7f0aec7c186c6adda97c3f8a Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Tue, 7 Jul 2026 11:15:22 +0200
Subject: [PATCH 15/49] fix: add lib es2023 to tsconfig.base.json for
 findLastIndex support

---
 tsconfig.base.json | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tsconfig.base.json b/tsconfig.base.json
index 42dfb4a53..e472afeeb 100644
--- a/tsconfig.base.json
+++ b/tsconfig.base.json
@@ -1,6 +1,7 @@
 {
   "compilerOptions": {
     "target": "ES2022",
+    "lib": ["es2023"],
     "module": "Node16",
     "declaration": true,
     "declarationMap": true,

From a18ed9b0d3911fc378d9f11b8319ec7e9162986a Mon Sep 17 00:00:00 2001
From: "sap-ai-sdk-bot[bot]"
 <272306433+sap-ai-sdk-bot[bot]@users.noreply.github.com>
Date: Tue, 7 Jul 2026 09:16:32 +0000
Subject: [PATCH 16/49] fix: Changes from lint

---
 packages/orchestration/src/orchestration-types.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/orchestration/src/orchestration-types.ts b/packages/orchestration/src/orchestration-types.ts
index 095f69419..bf06e09a6 100644
--- a/packages/orchestration/src/orchestration-types.ts
+++ b/packages/orchestration/src/orchestration-types.ts
@@ -681,8 +681,7 @@ export interface DocumentTranslationApplyToSelector {
  * Target language for translation, either a language code or a selector configuration.
  */
 export type TranslationTargetLanguage =
-  | string
-  | DocumentTranslationApplyToSelector;
+  string | DocumentTranslationApplyToSelector;
 
 /**
  * Input parameters for translation configuration.

From eb5dd487290226fb44c8874090a68d2292022524 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Tue, 7 Jul 2026 15:33:56 +0200
Subject: [PATCH 17/49] fix: omit messages key entirely when no remaining
 messages

---
 packages/orchestration/src/util/module-config.ts | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 143458d5e..95aaa04ea 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -366,9 +366,10 @@ export function constructCompletionPostRequest(
   let moduleRequest = request;
   if (splitIndex > 0 && request) {
     const remaining = messages.slice(splitIndex);
+    const { messages: _messages, ...rest } = request;
     moduleRequest = {
-      ...request,
-      messages: remaining.length ? remaining : undefined
+      ...rest,
+      ...(remaining.length && { messages: remaining })
     };
   }
 

From 6d23c8b042e8869f1cf0f1b7f5e5004016143dfd Mon Sep 17 00:00:00 2001
From: Injun Park <injun.park@sap.com>
Date: Wed, 8 Jul 2026 13:21:55 +0200
Subject: [PATCH 18/49] Apply suggestions from code review

Co-authored-by: David Knaack <david.knaack@sap.com>
---
 packages/orchestration/src/util/module-config.ts | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 95aaa04ea..515f29f90 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -479,15 +479,6 @@ function getMessageSplitIndex(
     return 0;
   }
 
-  const hasStaticPrompt = configs.some(c => {
-    const prompt = c?.promptTemplating?.prompt;
-    return (
-      isTemplate(prompt) && (prompt.template?.length || prompt.tools?.length)
-    );
-  });
-  if (hasStaticPrompt) {
-    return 0;
-  }
 
   return messages.findLastIndex(msg => msg.role === 'tool') + 1;
 }

From 92d489793c8c41e1fde2bd997690924d1532a72c Mon Sep 17 00:00:00 2001
From: "sap-ai-sdk-bot[bot]"
 <272306433+sap-ai-sdk-bot[bot]@users.noreply.github.com>
Date: Wed, 8 Jul 2026 11:23:05 +0000
Subject: [PATCH 19/49] fix: Changes from lint

---
 packages/orchestration/src/util/module-config.ts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 515f29f90..d78307bc8 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -479,7 +479,6 @@ function getMessageSplitIndex(
     return 0;
   }
 
-
   return messages.findLastIndex(msg => msg.role === 'tool') + 1;
 }
 

From 2f3103199f2ee9306051ec64e59e72d299257631 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 8 Jul 2026 16:09:28 +0200
Subject: [PATCH 20/49] fix after david's feedback

---
 .changeset/yummy-ducks-run.md                 |  2 +-
 ...hestration-completion-post-request.test.ts | 19 ++++++----
 .../orchestration/src/util/module-config.ts   | 27 ++++---------
 sample-code/src/index.ts                      |  3 +-
 sample-code/src/orchestration.ts              | 38 +++++++++++++++++++
 tests/e2e-tests/src/orchestration.test.ts     | 12 +++++-
 6 files changed, 72 insertions(+), 29 deletions(-)

diff --git a/.changeset/yummy-ducks-run.md b/.changeset/yummy-ducks-run.md
index 0449b89d8..1d82fe7b1 100644
--- a/.changeset/yummy-ducks-run.md
+++ b/.changeset/yummy-ducks-run.md
@@ -2,4 +2,4 @@
 '@sap-ai-sdk/orchestration': patch
 ---
 
-[Fix] Automatically route `role: 'tool'` messages (and all preceding messages) from `messages` to `messages_history` to bypass prompt templating, unless placeholder values are provided.
+[Fix] Automatically route `role: 'tool'` messages (and all preceding messages) from `messages` to `messages_history` to bypass prompt templating, unless placeholder values are provided. When no `prompt` property is set on the config, all messages are routed to `messages_history`.
diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index 2e967fe07..24bd97ae2 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -439,19 +439,21 @@ describe('construct completion post request', () => {
       expect(result.messages_history).toEqual([assistantMessage]);
     });
 
-    it('should not auto-route when config has a static prompt template', () => {
-      // static template present → auto-routing disabled, tool message stays in prompt.template
+    it('should auto-route tool messages even when config has a static prompt template', () => {
       const result: any = constructCompletionPostRequest(defaultConfig, {
         messages: [assistantMessage, toolMessage, userMessage]
       });
 
-      expect(result.messages_history).toBeUndefined();
+      expect(result.messages_history).toEqual([assistantMessage, toolMessage]);
       expect(
         result.config.modules.prompt_templating.prompt.template
-      ).toContainEqual(toolMessage);
+      ).not.toContainEqual(toolMessage);
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).toContainEqual(userMessage);
     });
 
-    it('should not auto-route when config has prompt.tools (no template)', () => {
+    it('should auto-route tool messages when config has prompt.tools (no template)', () => {
       const toolsConfig: OrchestrationModuleConfig = {
         promptTemplating: {
           model: { name: 'gpt-5.4-nano' },
@@ -473,10 +475,13 @@ describe('construct completion post request', () => {
         messages: [assistantMessage, toolMessage, userMessage]
       });
 
-      expect(result.messages_history).toBeUndefined();
+      expect(result.messages_history).toEqual([assistantMessage, toolMessage]);
       expect(
         result.config.modules.prompt_templating.prompt.template
-      ).toContainEqual(toolMessage);
+      ).toContainEqual(userMessage);
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).not.toContainEqual(toolMessage);
     });
   });
 });
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index d78307bc8..9efe8a892 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -416,12 +416,9 @@ function buildCompletionModulesConfig(
     config;
 
   // prompt is not a string here as it is already parsed in `parseAndMergeTemplating` method
-  const prompt = {
-    ...(promptTemplating.prompt as Template | TemplateRef)
-  };
-
-  // If promptTemplating.prompt is not defined, we initialize it with an empty Template object
-  promptTemplating.prompt = promptTemplating.prompt || { template: [] };
+  const prompt: Template | TemplateRef = promptTemplating.prompt
+    ? { ...(promptTemplating.prompt as Template | TemplateRef) }
+    : { template: [] };
 
   if (isTemplate(prompt)) {
     if (!prompt.template?.length && !request?.messages?.length) {
@@ -452,9 +449,9 @@ function buildCompletionModulesConfig(
  *
  * Routing is skipped when:
  * - placeholder values are set (user has opted into templating)
- * - any config has a non-empty static prompt.template or prompt.tools.
+ * - any config has a `prompt` property (Template or TemplateRef)
  *
- * When a TemplateRef is used, all messages are routed (splitIndex = messages.length).
+ * When no config has a `prompt` property, all messages are routed (splitIndex = messages.length).
  * @param configs - The orchestration module configurations.
  * @param messages - The chat messages to evaluate.
  * @param request - The optional chat completion request containing placeholder values.
@@ -465,10 +462,10 @@ function getMessageSplitIndex(
   messages: ChatMessage[],
   request?: ChatCompletionRequest
 ): number {
-  const usesTemplateRef = configs.some(c =>
-    isTemplateRef(c?.promptTemplating?.prompt || {})
+  const usesTemplate = configs.some(c =>
+    c?.promptTemplating?.hasOwnProperty('prompt')
   );
-  if (usesTemplateRef) {
+  if (!usesTemplate) {
     return messages.length;
   }
 
@@ -490,14 +487,6 @@ function isTemplate(templating: unknown): templating is Template {
   );
 }
 
-function isTemplateRef(templating: unknown): templating is TemplateRef {
-  return (
-    !!templating &&
-    typeof templating === 'object' &&
-    'template_ref' in templating
-  );
-}
-
 /**
  * Constructs an embedding post request from the given configuration and request.
  * @internal
diff --git a/sample-code/src/index.ts b/sample-code/src/index.ts
index 57c1bb165..93e92f860 100644
--- a/sample-code/src/index.ts
+++ b/sample-code/src/index.ts
@@ -37,7 +37,8 @@ export {
   orchestrationSonarStreamWithCitations,
   orchestrationStreamWithFallbackConfigs,
   orchestrationToolResultInMessages,
-  orchestrationToolResultMaskingInMessagesHistory
+  orchestrationToolResultMaskingInMessagesHistory,
+  orchestrationToolLastMessageInMessages
 } from './orchestration.js';
 export {
   invoke,
diff --git a/sample-code/src/orchestration.ts b/sample-code/src/orchestration.ts
index 180496a91..a91a40a9d 100644
--- a/sample-code/src/orchestration.ts
+++ b/sample-code/src/orchestration.ts
@@ -864,6 +864,44 @@ export async function orchestrationToolResultMaskingInMessagesHistory(): Promise
   });
 }
 
+/**
+ * Verify that the SDK correctly routes all messages to messages_history when
+ * the last message is a tool result (no trailing user message).
+ * @returns The orchestration service response.
+ */
+export async function orchestrationToolLastMessageInMessages(): Promise<OrchestrationResponse> {
+  const client = new OrchestrationClient({
+    promptTemplating: {
+      model: { name: 'anthropic--claude-4.5-haiku' }
+    }
+  });
+
+  const assistantMessage: AssistantChatMessage = {
+    role: 'assistant',
+    tool_calls: [
+      {
+        id: 'call_abc123',
+        type: 'function',
+        function: { name: 'lookup', arguments: '{"id":"1"}' }
+      }
+    ]
+  };
+
+  const toolMessage: ToolChatMessage = {
+    role: 'tool',
+    content: 'Result: done',
+    tool_call_id: 'call_abc123'
+  };
+
+  return client.chatCompletion({
+    messages: [
+      { role: 'user', content: 'Call the lookup tool.' },
+      assistantMessage,
+      toolMessage
+    ]
+  });
+}
+
 /**
  * Use translation module for input and output translation with advanced features.
  * @returns The orchestration service response.
diff --git a/tests/e2e-tests/src/orchestration.test.ts b/tests/e2e-tests/src/orchestration.test.ts
index e569fa88e..f4b57f411 100644
--- a/tests/e2e-tests/src/orchestration.test.ts
+++ b/tests/e2e-tests/src/orchestration.test.ts
@@ -26,7 +26,8 @@ import {
   orchestrationSonarStreamWithCitations,
   orchestrationStreamWithFallbackConfigs,
   orchestrationToolResultInMessages,
-  orchestrationToolResultMaskingInMessagesHistory
+  orchestrationToolResultMaskingInMessagesHistory,
+  orchestrationToolLastMessageInMessages
 } from '@sap-ai-sdk/sample-code';
 import {
   OrchestrationClient,
@@ -358,5 +359,14 @@ describe('orchestration', () => {
         roles.lastIndexOf('tool')
       );
     });
+
+    it('should succeed when the last message is of type tool', async () => {
+      const response = await orchestrationToolLastMessageInMessages();
+      expect(response.getContent()).toEqual(expect.any(String));
+
+      const templating = response.getIntermediateResults().templating;
+      const roles = templating!.map(m => m.role);
+      expect(roles[roles.length - 1]).toBe('tool');
+    });
   });
 });

From 22317d3e31c1ad19c825646e44a9f1e0f5b8faaf Mon Sep 17 00:00:00 2001
From: "sap-ai-sdk-bot[bot]"
 <272306433+sap-ai-sdk-bot[bot]@users.noreply.github.com>
Date: Wed, 8 Jul 2026 14:10:54 +0000
Subject: [PATCH 21/49] fix: Changes from lint

---
 packages/orchestration/src/util/module-config.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 9efe8a892..6ba1da077 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -449,7 +449,7 @@ function buildCompletionModulesConfig(
  *
  * Routing is skipped when:
  * - placeholder values are set (user has opted into templating)
- * - any config has a `prompt` property (Template or TemplateRef)
+ * - any config has a `prompt` property (Template or TemplateRef).
  *
  * When no config has a `prompt` property, all messages are routed (splitIndex = messages.length).
  * @param configs - The orchestration module configurations.

From 1b2f9933619dbea60e2dff80d2d923f0923775ae Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 8 Jul 2026 16:30:42 +0200
Subject: [PATCH 22/49] fix for ci

---
 packages/orchestration/src/util/module-config.ts | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 6ba1da077..6a1272781 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -421,7 +421,11 @@ function buildCompletionModulesConfig(
     : { template: [] };
 
   if (isTemplate(prompt)) {
-    if (!prompt.template?.length && !request?.messages?.length) {
+    if (
+      promptTemplating.prompt &&
+      !prompt.template?.length &&
+      !request?.messages?.length
+    ) {
       throw new Error('Either a prompt template or messages must be defined.');
     }
     prompt.template = [
@@ -469,6 +473,14 @@ function getMessageSplitIndex(
     return messages.length;
   }
 
+  const usesTemplateRef = configs.some(c => {
+    const p = c?.promptTemplating?.prompt;
+    return !!p && typeof p === 'object' && 'template_ref' in p;
+  });
+  if (usesTemplateRef) {
+    return messages.length;
+  }
+
   const hasPlaceholderValues =
     !!request?.placeholderValues &&
     Object.keys(request.placeholderValues).length > 0;

From 16c7c951fc42d092d569a08c1522898c8d50bc4a Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 8 Jul 2026 20:43:02 +0200
Subject: [PATCH 23/49] fix ci error

---
 .../src/orchestration/client.test.ts          | 166 ++----------------
 1 file changed, 13 insertions(+), 153 deletions(-)

diff --git a/packages/langchain/src/orchestration/client.test.ts b/packages/langchain/src/orchestration/client.test.ts
index 0794b99e6..f92c073cb 100644
--- a/packages/langchain/src/orchestration/client.test.ts
+++ b/packages/langchain/src/orchestration/client.test.ts
@@ -81,19 +81,7 @@ describe('orchestration service client', () => {
   ) {
     mockInference(
       {
-        data: constructCompletionPostRequest(
-          {
-            ...config,
-            promptTemplating: {
-              ...config.promptTemplating,
-              prompt: {
-                template: messages
-              }
-            }
-          },
-          { messages: [] },
-          isStream
-        )
+        data: constructCompletionPostRequest(config, { messages }, isStream)
       },
       {
         data: response,
@@ -403,19 +391,7 @@ describe('orchestration service client', () => {
     it('supports streaming responses', async () => {
       mockInference(
         {
-          data: constructCompletionPostRequest(
-            {
-              ...config,
-              promptTemplating: {
-                ...config.promptTemplating,
-                prompt: {
-                  template: messages
-                }
-              }
-            },
-            { messages: [] },
-            true
-          )
+          data: constructCompletionPostRequest(config, { messages }, true)
         },
         {
           data: mockResponseStream,
@@ -437,19 +413,7 @@ describe('orchestration service client', () => {
     it('supports auto-streaming responses', async () => {
       mockInference(
         {
-          data: constructCompletionPostRequest(
-            {
-              ...config,
-              promptTemplating: {
-                ...config.promptTemplating,
-                prompt: {
-                  template: messages
-                }
-              }
-            },
-            { messages: [] },
-            true
-          )
+          data: constructCompletionPostRequest(config, { messages }, true)
         },
         {
           data: mockResponseStream,
@@ -476,19 +440,7 @@ describe('orchestration service client', () => {
     it('has langchain handle disabling streaming via disableStreaming flag in stream', async () => {
       mockInference(
         {
-          data: constructCompletionPostRequest(
-            {
-              ...config,
-              promptTemplating: {
-                ...config.promptTemplating,
-                prompt: {
-                  template: messages
-                }
-              }
-            },
-            { messages: [] },
-            false
-          )
+          data: constructCompletionPostRequest(config, { messages }, false)
         },
         {
           data: mockResponse,
@@ -552,19 +504,7 @@ describe('orchestration service client', () => {
     it('streams and aborts with a signal', async () => {
       mockInference(
         {
-          data: constructCompletionPostRequest(
-            {
-              ...config,
-              promptTemplating: {
-                ...config.promptTemplating,
-                prompt: {
-                  template: messages
-                }
-              }
-            },
-            { messages: [] },
-            true
-          )
+          data: constructCompletionPostRequest(config, { messages }, true)
         },
         {
           data: mockResponseStream,
@@ -588,19 +528,7 @@ describe('orchestration service client', () => {
     it('streams with a callback', async () => {
       mockInference(
         {
-          data: constructCompletionPostRequest(
-            {
-              ...config,
-              promptTemplating: {
-                ...config.promptTemplating,
-                prompt: {
-                  template: messages
-                }
-              }
-            },
-            { messages: [] },
-            true
-          )
+          data: constructCompletionPostRequest(config, { messages }, true)
         },
         {
           data: mockResponseStream,
@@ -636,19 +564,7 @@ describe('orchestration service client', () => {
     it('supports streaming responses with tool calls', async () => {
       mockInference(
         {
-          data: constructCompletionPostRequest(
-            {
-              ...config,
-              promptTemplating: {
-                ...config.promptTemplating,
-                prompt: {
-                  template: messages
-                }
-              }
-            },
-            { messages: [] },
-            true
-          )
+          data: constructCompletionPostRequest(config, { messages }, true)
         },
         {
           data: mockResponseStreamToolCalls,
@@ -677,19 +593,7 @@ describe('orchestration service client', () => {
   it('streams when invoked in a streaming langgraph', async () => {
     mockInference(
       {
-        data: constructCompletionPostRequest(
-          {
-            ...config,
-            promptTemplating: {
-              ...config.promptTemplating,
-              prompt: {
-                template: messages
-              }
-            }
-          },
-          { messages: [] },
-          true
-        )
+        data: constructCompletionPostRequest(config, { messages }, true)
       },
       {
         data: mockResponseStream,
@@ -755,27 +659,8 @@ describe('orchestration service client', () => {
       mockInference(
         {
           data: constructCompletionPostRequest(
-            [
-              {
-                ...primaryConfig,
-                promptTemplating: {
-                  ...primaryConfig.promptTemplating,
-                  prompt: {
-                    template: messages
-                  }
-                }
-              },
-              {
-                ...fallbackConfig,
-                promptTemplating: {
-                  ...fallbackConfig.promptTemplating,
-                  prompt: {
-                    template: messages
-                  }
-                }
-              }
-            ],
-            { messages: [] }
+            [primaryConfig, fallbackConfig],
+            { messages }
           )
         },
         {
@@ -812,27 +697,8 @@ describe('orchestration service client', () => {
       mockInference(
         {
           data: constructCompletionPostRequest(
-            [
-              {
-                ...primaryConfig,
-                promptTemplating: {
-                  ...primaryConfig.promptTemplating,
-                  prompt: {
-                    template: messages
-                  }
-                }
-              },
-              {
-                ...fallbackConfig,
-                promptTemplating: {
-                  ...fallbackConfig.promptTemplating,
-                  prompt: {
-                    template: messages
-                  }
-                }
-              }
-            ],
-            { messages: [] },
+            [primaryConfig, fallbackConfig],
+            { messages },
             true
           )
         },
@@ -891,9 +757,6 @@ describe('orchestration service client', () => {
                       ...primaryConfig.promptTemplating.model.params,
                       stop: ['PRIMARY_STOP', 'END']
                     }
-                  },
-                  prompt: {
-                    template: messages
                   }
                 }
               },
@@ -907,14 +770,11 @@ describe('orchestration service client', () => {
                       ...fallbackConfig.promptTemplating.model.params,
                       stop: ['FALLBACK_STOP', 'END']
                     }
-                  },
-                  prompt: {
-                    template: messages
                   }
                 }
               }
             ],
-            { messages: [] }
+            { messages }
           )
         },
         {

From 8cf9a2d8ecea1df179ab5db801aae6771b9a4e57 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 8 Jul 2026 20:52:27 +0200
Subject: [PATCH 24/49] fix ci error

---
 packages/langchain/src/orchestration/client.test.ts | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/packages/langchain/src/orchestration/client.test.ts b/packages/langchain/src/orchestration/client.test.ts
index f92c073cb..4df6854f2 100644
--- a/packages/langchain/src/orchestration/client.test.ts
+++ b/packages/langchain/src/orchestration/client.test.ts
@@ -77,11 +77,16 @@ describe('orchestration service client', () => {
       delay?: number;
     },
     status: number = 200,
-    isStream?: boolean
+    isStream?: boolean,
+    inputMessages = messages
   ) {
     mockInference(
       {
-        data: constructCompletionPostRequest(config, { messages }, isStream)
+        data: constructCompletionPostRequest(
+          config,
+          { messages: inputMessages },
+          isStream
+        )
       },
       {
         data: response,
@@ -157,7 +162,8 @@ describe('orchestration service client', () => {
         mockResponseStream,
         { delay: 2000 },
         200,
-        true
+        true,
+        []
       );
 
       let finalOutput: AIMessageChunk | undefined;

From 6048e391925a94c3abf1a6bffc6b1b4d898e2f06 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 8 Jul 2026 20:58:41 +0200
Subject: [PATCH 25/49] fix ci error(grammar on yummy-ducks-run

---
 .changeset/yummy-ducks-run.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/.changeset/yummy-ducks-run.md b/.changeset/yummy-ducks-run.md
index 1d82fe7b1..386a03594 100644
--- a/.changeset/yummy-ducks-run.md
+++ b/.changeset/yummy-ducks-run.md
@@ -2,4 +2,5 @@
 '@sap-ai-sdk/orchestration': patch
 ---
 
-[Fix] Automatically route `role: 'tool'` messages (and all preceding messages) from `messages` to `messages_history` to bypass prompt templating, unless placeholder values are provided. When no `prompt` property is set on the config, all messages are routed to `messages_history`.
+[Fix] Automatically route `role: 'tool'` messages (and all preceding messages) from `messages` to `messages_history` to bypass prompt templating, unless placeholder values are provided.
+When no `prompt` property is set on the config, all messages are routed to `messages_history`.

From 64a6c631568a34c1a200d0318ab945dc0f19c310 Mon Sep 17 00:00:00 2001
From: Injun Park <injun.park@sap.com>
Date: Fri, 10 Jul 2026 10:23:55 +0200
Subject: [PATCH 26/49] Update packages/orchestration/src/util/module-config.ts

Co-authored-by: David Knaack <david.knaack@sap.com>
---
 packages/orchestration/src/util/module-config.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 6a1272781..483a92312 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -483,7 +483,7 @@ function getMessageSplitIndex(
 
   const hasPlaceholderValues =
     !!request?.placeholderValues &&
-    Object.keys(request.placeholderValues).length > 0;
+    Object.keys(request.placeholderValues).length;
   if (hasPlaceholderValues) {
     return 0;
   }

From 2901e34b09b332529b7690626683810c78ae33c3 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Fri, 10 Jul 2026 12:47:04 +0200
Subject: [PATCH 27/49] fix: replace getMessageSplitIndex with
 shouldRouteMessagesToHistory boolean

---
 .changeset/yummy-ducks-run.md                 |   5 +-
 ...hestration-completion-post-request.test.ts |  71 +++++-------
 .../orchestration/src/orchestration-types.ts  |   9 +-
 .../orchestration/src/util/module-config.ts   | 103 +++++++++---------
 4 files changed, 84 insertions(+), 104 deletions(-)

diff --git a/.changeset/yummy-ducks-run.md b/.changeset/yummy-ducks-run.md
index 386a03594..5966f6790 100644
--- a/.changeset/yummy-ducks-run.md
+++ b/.changeset/yummy-ducks-run.md
@@ -2,5 +2,6 @@
 '@sap-ai-sdk/orchestration': patch
 ---
 
-[Fix] Automatically route `role: 'tool'` messages (and all preceding messages) from `messages` to `messages_history` to bypass prompt templating, unless placeholder values are provided.
-When no `prompt` property is set on the config, all messages are routed to `messages_history`.
+[Fix] Automatically route all `messages` to `messages_history` to bypass prompt templating when no `prompt` is configured or a `TemplateRef` is used.
+Routing is skipped when a `Template` is configured or `placeholderValues` are provided.
+
diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index 24bd97ae2..f1ed3d22d 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -338,7 +338,7 @@ describe('construct completion post request', () => {
     expect(completionPostRequest).toEqual(expectedCompletionPostRequest);
   });
 
-  describe('tool message auto-routing', () => {
+  describe('messages routing to messages_history', () => {
     const toolCallId = 'call_abc123';
     const assistantMessage = {
       role: 'assistant' as const,
@@ -357,34 +357,28 @@ describe('construct completion post request', () => {
     };
     const userMessage = { role: 'user' as const, content: 'Summarize.' };
 
-    // Config without a static template — auto-routing is active
+    // Config without a prompt — shouldRouteMessagesToHistory returns true
     const noTemplateConfig: OrchestrationModuleConfig = {
       promptTemplating: {
-        model: { name: 'gpt-5.4-nano' },
-        prompt: { template: [] }
+        model: { name: 'gpt-5.4-nano' }
       }
     };
 
-    it('should route tool messages from messages to messages_history', () => {
+    it('should route all messages to messages_history when no prompt is configured', () => {
+      const followUp = { role: 'user' as const, content: 'Follow up.' };
       const result: any = constructCompletionPostRequest(noTemplateConfig, {
         messages: [
           userMessage,
           toolMessage,
-          { role: 'user' as const, content: 'Follow up.' }
+          followUp
         ]
       });
 
-      expect(result.messages_history).toContainEqual(userMessage);
-      expect(result.messages_history).toContainEqual(toolMessage);
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).not.toContainEqual(toolMessage);
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).not.toContainEqual(userMessage);
+      expect(result.messages_history).toEqual([userMessage, toolMessage, followUp]);
+      expect(result.config.modules.prompt_templating.prompt).toBeUndefined();
     });
 
-    it('should preserve existing messagesHistory when appending tool messages', () => {
+    it('should preserve existing messagesHistory when routing all messages', () => {
       const followUpUser = { role: 'user' as const, content: 'Follow up.' };
       const result = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage, toolMessage, followUpUser],
@@ -394,66 +388,56 @@ describe('construct completion post request', () => {
       expect(result.messages_history).toEqual([
         assistantMessage,
         userMessage,
-        toolMessage
+        toolMessage,
+        followUpUser
       ]);
     });
 
-    it('should not affect non-tool messages', () => {
+    it('should route all messages to history even without tool messages', () => {
       const result: any = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage]
       });
 
-      expect(result.messages_history).toBeUndefined();
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).toContainEqual(userMessage);
+      expect(result.messages_history).toEqual([userMessage]);
+      expect(result.config.modules.prompt_templating.prompt).toBeUndefined();
     });
 
-    it('should preserve chronological message order across the split', () => {
+    it('should preserve chronological message order in messages_history', () => {
       const followUpUser = { role: 'user' as const, content: 'Follow up.' };
       const result: any = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage, assistantMessage, toolMessage, followUpUser]
       });
 
-      // messages before and including last tool go to messages_history in order
       expect(result.messages_history).toEqual([
         userMessage,
         assistantMessage,
-        toolMessage
+        toolMessage,
+        followUpUser
       ]);
-      // only messages after the last tool stay in prompt.template
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).toContainEqual(followUpUser);
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).not.toContainEqual(toolMessage);
+      expect(result.config.modules.prompt_templating.prompt).toBeUndefined();
     });
 
-    it('should emit messages_history when only messagesHistory is provided (no tool messages)', () => {
+    it('should combine existing messagesHistory with routed messages', () => {
       const result = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage],
         messagesHistory: [assistantMessage]
       });
 
-      expect(result.messages_history).toEqual([assistantMessage]);
+      expect(result.messages_history).toEqual([assistantMessage, userMessage]);
     });
 
-    it('should auto-route tool messages even when config has a static prompt template', () => {
+    it('should not route messages when config has a static prompt template', () => {
       const result: any = constructCompletionPostRequest(defaultConfig, {
         messages: [assistantMessage, toolMessage, userMessage]
       });
 
-      expect(result.messages_history).toEqual([assistantMessage, toolMessage]);
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).not.toContainEqual(toolMessage);
+      expect(result.messages_history).toBeUndefined();
       expect(
         result.config.modules.prompt_templating.prompt.template
-      ).toContainEqual(userMessage);
+      ).toContainEqual(toolMessage);
     });
 
-    it('should auto-route tool messages when config has prompt.tools (no template)', () => {
+    it('should not route messages when config has prompt.tools', () => {
       const toolsConfig: OrchestrationModuleConfig = {
         promptTemplating: {
           model: { name: 'gpt-5.4-nano' },
@@ -475,13 +459,10 @@ describe('construct completion post request', () => {
         messages: [assistantMessage, toolMessage, userMessage]
       });
 
-      expect(result.messages_history).toEqual([assistantMessage, toolMessage]);
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).toContainEqual(userMessage);
+      expect(result.messages_history).toBeUndefined();
       expect(
         result.config.modules.prompt_templating.prompt.template
-      ).not.toContainEqual(toolMessage);
+      ).toContainEqual(toolMessage);
     });
   });
 });
diff --git a/packages/orchestration/src/orchestration-types.ts b/packages/orchestration/src/orchestration-types.ts
index bf06e09a6..cb7928039 100644
--- a/packages/orchestration/src/orchestration-types.ts
+++ b/packages/orchestration/src/orchestration-types.ts
@@ -46,10 +46,11 @@ export interface ChatCompletionRequest {
 
   /**
    * New chat messages, including template messages.
-   * Messages with `role: 'tool'` — and all messages preceding them — are automatically
-   * routed to `messages_history` to bypass prompt templating. This prevents tool results
-   * from external systems containing `{{?...}}` syntax from being misinterpreted as
-   * template placeholders. To verify the final message order sent to the LLM, use
+   * All messages are automatically routed to `messages_history` when no `prompt` is configured
+   * or a `TemplateRef` is used, bypassing prompt templating entirely.
+   * When a `Template` is configured, messages are merged into `prompt.template` as usual.
+   * Routing is skipped when `placeholderValues` are provided.
+   * To verify the final message order sent to the LLM, use
    * `response.getIntermediateResults().templating`.
    * @example
    * messages: [
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 483a92312..b80eb48a0 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -11,7 +11,6 @@ import {
   type EmbeddingRequest
 } from '../orchestration-types.js';
 import type {
-  ChatMessage,
   CompletionPostRequest,
   CompletionRequestConfigurationReferenceById,
   CompletionRequestConfigurationReferenceByNameScenarioVersion,
@@ -360,17 +359,12 @@ export function constructCompletionPostRequest(
   // - Config array (OrchestrationModuleConfigList) → array of ModuleConfigs for fallback behavior
 
   const configs = Array.isArray(config) ? config : [config];
-  const messages = request?.messages || [];
-  const splitIndex = getMessageSplitIndex(configs, messages, request);
+  const routeToHistory = shouldRouteMessagesToHistory(configs, request);
 
   let moduleRequest = request;
-  if (splitIndex > 0 && request) {
-    const remaining = messages.slice(splitIndex);
+  if (routeToHistory && request) {
     const { messages: _messages, ...rest } = request;
-    moduleRequest = {
-      ...rest,
-      ...(remaining.length && { messages: remaining })
-    };
+    moduleRequest = rest;
   }
 
   /**
@@ -393,8 +387,11 @@ export function constructCompletionPostRequest(
     : { modules: moduleConfigurations };
 
   const messagesHistory =
-    splitIndex > 0 || request?.messagesHistory?.length
-      ? [...(request?.messagesHistory || []), ...messages.slice(0, splitIndex)]
+    routeToHistory || request?.messagesHistory?.length
+      ? [
+          ...(request?.messagesHistory || []),
+          ...(request?.messages || [])
+        ]
       : undefined;
 
   return {
@@ -415,17 +412,30 @@ function buildCompletionModulesConfig(
   const { promptTemplating, filtering, masking, grounding, translation } =
     config;
 
+  const modules = {
+    ...(filtering && Object.keys(filtering).length && { filtering }),
+    ...(masking && Object.keys(masking).length && { masking }),
+    ...(grounding && Object.keys(grounding).length && { grounding }),
+    ...(translation && Object.keys(translation).length && { translation })
+  };
+
   // prompt is not a string here as it is already parsed in `parseAndMergeTemplating` method
-  const prompt: Template | TemplateRef = promptTemplating.prompt
-    ? { ...(promptTemplating.prompt as Template | TemplateRef) }
-    : { template: [] };
+  if (!promptTemplating.prompt) {
+    // No prompt configured: messages are already routed to messages_history upstream.
+    // Omit the prompt key entirely — it is optional per the service API.
+    const { prompt: _prompt, ...promptTemplatingWithoutPrompt } = promptTemplating;
+    return {
+      prompt_templating: promptTemplatingWithoutPrompt as PromptTemplatingModuleConfig,
+      ...modules
+    };
+  }
+
+  const prompt: Template | TemplateRef = {
+    ...(promptTemplating.prompt as Template | TemplateRef)
+  };
 
   if (isTemplate(prompt)) {
-    if (
-      promptTemplating.prompt &&
-      !prompt.template?.length &&
-      !request?.messages?.length
-    ) {
+    if (!prompt.template?.length && !request?.messages?.length) {
       throw new Error('Either a prompt template or messages must be defined.');
     }
     prompt.template = [
@@ -439,56 +449,43 @@ function buildCompletionModulesConfig(
       ...promptTemplating,
       prompt
     },
-    ...(filtering && Object.keys(filtering).length && { filtering }),
-    ...(masking && Object.keys(masking).length && { masking }),
-    ...(grounding && Object.keys(grounding).length && { grounding }),
-    ...(translation && Object.keys(translation).length && { translation })
+    ...modules
   };
 }
 
 /**
- * Determines the split index for routing messages to messages_history.
- * Messages before splitIndex bypass prompt templating; messages from splitIndex onward
- * stay in prompt.template.
+ * Determines whether all messages should be routed to messages_history,
+ * bypassing prompt templating entirely.
  *
- * Routing is skipped when:
- * - placeholder values are set (user has opted into templating)
- * - any config has a `prompt` property (Template or TemplateRef).
+ * Routes to history when:
+ * - no `prompt` is configured (messages have nowhere to be merged)
+ * - a TemplateRef is used (remote template, messages cannot be merged in)
  *
- * When no config has a `prompt` property, all messages are routed (splitIndex = messages.length).
+ * Does NOT route to history when:
+ * - a Template is set (messages are merged into prompt.template)
+ * - placeholder_values are provided (user has opted into templating)
  * @param configs - The orchestration module configurations.
- * @param messages - The chat messages to evaluate.
- * @param request - The optional chat completion request containing placeholder values.
- * @returns The index at which to split messages between messages_history and prompt.template.
+ * @param request - The optional chat completion request.
+ * @returns True if all messages should be routed to messages_history.
  */
-function getMessageSplitIndex(
+function shouldRouteMessagesToHistory(
   configs: OrchestrationModuleConfig[],
-  messages: ChatMessage[],
   request?: ChatCompletionRequest
-): number {
-  const usesTemplate = configs.some(c =>
-    c?.promptTemplating?.hasOwnProperty('prompt')
-  );
-  if (!usesTemplate) {
-    return messages.length;
-  }
-
-  const usesTemplateRef = configs.some(c => {
-    const p = c?.promptTemplating?.prompt;
-    return !!p && typeof p === 'object' && 'template_ref' in p;
-  });
-  if (usesTemplateRef) {
-    return messages.length;
-  }
-
+): boolean {
   const hasPlaceholderValues =
     !!request?.placeholderValues &&
     Object.keys(request.placeholderValues).length;
   if (hasPlaceholderValues) {
-    return 0;
+    return false;
   }
 
-  return messages.findLastIndex(msg => msg.role === 'tool') + 1;
+  return configs.some(c => {
+    const prompt = c?.promptTemplating?.prompt;
+    if (!prompt) {
+      return true;
+    }
+    return typeof prompt === 'object' && 'template_ref' in prompt;
+  });
 }
 
 function isTemplate(templating: unknown): templating is Template {

From 424b4624141cc7439573767927ce9a79492c05dd Mon Sep 17 00:00:00 2001
From: "sap-ai-sdk-bot[bot]"
 <272306433+sap-ai-sdk-bot[bot]@users.noreply.github.com>
Date: Fri, 10 Jul 2026 11:18:31 +0000
Subject: [PATCH 28/49] fix: Changes from lint

---
 .../orchestration-completion-post-request.test.ts | 12 ++++++------
 packages/orchestration/src/util/module-config.ts  | 15 +++++++--------
 2 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index f1ed3d22d..df7530f29 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -367,14 +367,14 @@ describe('construct completion post request', () => {
     it('should route all messages to messages_history when no prompt is configured', () => {
       const followUp = { role: 'user' as const, content: 'Follow up.' };
       const result: any = constructCompletionPostRequest(noTemplateConfig, {
-        messages: [
-          userMessage,
-          toolMessage,
-          followUp
-        ]
+        messages: [userMessage, toolMessage, followUp]
       });
 
-      expect(result.messages_history).toEqual([userMessage, toolMessage, followUp]);
+      expect(result.messages_history).toEqual([
+        userMessage,
+        toolMessage,
+        followUp
+      ]);
       expect(result.config.modules.prompt_templating.prompt).toBeUndefined();
     });
 
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index b80eb48a0..ca537e953 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -388,10 +388,7 @@ export function constructCompletionPostRequest(
 
   const messagesHistory =
     routeToHistory || request?.messagesHistory?.length
-      ? [
-          ...(request?.messagesHistory || []),
-          ...(request?.messages || [])
-        ]
+      ? [...(request?.messagesHistory || []), ...(request?.messages || [])]
       : undefined;
 
   return {
@@ -423,9 +420,11 @@ function buildCompletionModulesConfig(
   if (!promptTemplating.prompt) {
     // No prompt configured: messages are already routed to messages_history upstream.
     // Omit the prompt key entirely — it is optional per the service API.
-    const { prompt: _prompt, ...promptTemplatingWithoutPrompt } = promptTemplating;
+    const { prompt: _prompt, ...promptTemplatingWithoutPrompt } =
+      promptTemplating;
     return {
-      prompt_templating: promptTemplatingWithoutPrompt as PromptTemplatingModuleConfig,
+      prompt_templating:
+        promptTemplatingWithoutPrompt as PromptTemplatingModuleConfig,
       ...modules
     };
   }
@@ -459,11 +458,11 @@ function buildCompletionModulesConfig(
  *
  * Routes to history when:
  * - no `prompt` is configured (messages have nowhere to be merged)
- * - a TemplateRef is used (remote template, messages cannot be merged in)
+ * - a TemplateRef is used (remote template, messages cannot be merged in).
  *
  * Does NOT route to history when:
  * - a Template is set (messages are merged into prompt.template)
- * - placeholder_values are provided (user has opted into templating)
+ * - placeholder_values are provided (user has opted into templating).
  * @param configs - The orchestration module configurations.
  * @param request - The optional chat completion request.
  * @returns True if all messages should be routed to messages_history.

From f70451d349e94c3cb6247b328454582d79bcf85d Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Fri, 10 Jul 2026 13:27:32 +0200
Subject: [PATCH 29/49] fix: ensure prompt exists in config when cache_control
 is used

---
 packages/langchain/src/orchestration/client.ts | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/packages/langchain/src/orchestration/client.ts b/packages/langchain/src/orchestration/client.ts
index 442900d33..ed4eb7be1 100644
--- a/packages/langchain/src/orchestration/client.ts
+++ b/packages/langchain/src/orchestration/client.ts
@@ -509,6 +509,12 @@ export class OrchestrationClient extends BaseChatModel<
       }
     }
 
+    // Ensure prompt exists when cache_control is used so messages are merged
+    // into prompt.template rather than routed to messages_history.
+    if (options.cache_control) {
+      config.promptTemplating.prompt ??= {};
+    }
+
     return config;
   }
 

From 415e1dd0657ec8d87f311f07bbf7a6d660c05346 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Fri, 10 Jul 2026 13:30:29 +0200
Subject: [PATCH 30/49] fix: ensure cache_control messages stay in
 prompt.template

---
 packages/langchain/src/orchestration/client.test.ts | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/packages/langchain/src/orchestration/client.test.ts b/packages/langchain/src/orchestration/client.test.ts
index 97e9e1de0..e8eb86035 100644
--- a/packages/langchain/src/orchestration/client.test.ts
+++ b/packages/langchain/src/orchestration/client.test.ts
@@ -1311,12 +1311,8 @@ describe('orchestration service client', () => {
       mockInference(
         {
           data: (body: any) => {
-            const template =
-              body?.config?.modules?.prompt_templating?.prompt?.template;
-            return (
-              Array.isArray(template) &&
-              !JSON.stringify(template).includes('cache_control')
-            );
+            const bodyStr = JSON.stringify(body);
+            return !bodyStr.includes('cache_control');
           }
         },
         { data: mockResponse, status: 200 },

From f15904dabda5a071ec6ec822213119790bd641f7 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Mon, 13 Jul 2026 10:13:45 +0200
Subject: [PATCH 31/49] fix: address david feedback on cache_control and
 TemplateRef routing

---
 .../src/orchestration/client.test.ts          |  9 ++++---
 .../langchain/src/orchestration/client.ts     |  6 -----
 .../orchestration/src/util/module-config.ts   | 26 ++++++++++++-------
 3 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/packages/langchain/src/orchestration/client.test.ts b/packages/langchain/src/orchestration/client.test.ts
index e8eb86035..421969082 100644
--- a/packages/langchain/src/orchestration/client.test.ts
+++ b/packages/langchain/src/orchestration/client.test.ts
@@ -1262,12 +1262,13 @@ describe('orchestration service client', () => {
       expectedCacheControl: { type: string; ttl?: string }
     ): (body: any) => boolean {
       return (body: any): boolean => {
-        const template =
+        const messages: any[] =
+          body?.messages_history ??
           body?.config?.modules?.prompt_templating?.prompt?.template;
-        if (!Array.isArray(template) || messageIdx >= template.length) {
+        if (!Array.isArray(messages) || messageIdx >= messages.length) {
           return false;
         }
-        const target = template[messageIdx];
+        const target = messages[messageIdx];
         if (target?.role !== 'user' || !Array.isArray(target.content)) {
           return false;
         }
@@ -1279,7 +1280,7 @@ describe('orchestration service client', () => {
           block.cache_control?.type === expectedCacheControl.type &&
           block.cache_control?.ttl === expectedCacheControl.ttl;
 
-        const otherMessagesHaveBreakpoint = template.some(
+        const otherMessagesHaveBreakpoint = messages.some(
           (msg: any, idx: number) =>
             idx !== messageIdx && JSON.stringify(msg).includes('cache_control')
         );
diff --git a/packages/langchain/src/orchestration/client.ts b/packages/langchain/src/orchestration/client.ts
index ed4eb7be1..442900d33 100644
--- a/packages/langchain/src/orchestration/client.ts
+++ b/packages/langchain/src/orchestration/client.ts
@@ -509,12 +509,6 @@ export class OrchestrationClient extends BaseChatModel<
       }
     }
 
-    // Ensure prompt exists when cache_control is used so messages are merged
-    // into prompt.template rather than routed to messages_history.
-    if (options.cache_control) {
-      config.promptTemplating.prompt ??= {};
-    }
-
     return config;
   }
 
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index ca537e953..c26fa9b20 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -471,20 +471,26 @@ function shouldRouteMessagesToHistory(
   configs: OrchestrationModuleConfig[],
   request?: ChatCompletionRequest
 ): boolean {
-  const hasPlaceholderValues =
+  // TemplateRef always routes to history — remote template cannot merge messages,
+  // regardless of placeholderValues.
+  const hasTemplateRef = configs.some(c => {
+    const prompt = c?.promptTemplating?.prompt;
+    return !!prompt && typeof prompt === 'object' && 'template_ref' in prompt;
+  });
+  if (hasTemplateRef) {
+    return true;
+  }
+
+  // placeholderValues means the user opted into templating — do not route.
+  if (
     !!request?.placeholderValues &&
-    Object.keys(request.placeholderValues).length;
-  if (hasPlaceholderValues) {
+    Object.keys(request.placeholderValues).length > 0
+  ) {
     return false;
   }
 
-  return configs.some(c => {
-    const prompt = c?.promptTemplating?.prompt;
-    if (!prompt) {
-      return true;
-    }
-    return typeof prompt === 'object' && 'template_ref' in prompt;
-  });
+  // No prompt configured — messages have nowhere to be merged into.
+  return configs.some(c => !c?.promptTemplating?.prompt);
 }
 
 function isTemplate(templating: unknown): templating is Template {

From 780ad79f74ac1d8fa00e10f3841fea36c58fac18 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Mon, 13 Jul 2026 16:31:47 +0200
Subject: [PATCH 32/49] fix: rename messages to messageList to avoid variable
 shadowing in cache_control test

---
 packages/langchain/src/orchestration/client.test.ts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/packages/langchain/src/orchestration/client.test.ts b/packages/langchain/src/orchestration/client.test.ts
index 421969082..72dc37a8b 100644
--- a/packages/langchain/src/orchestration/client.test.ts
+++ b/packages/langchain/src/orchestration/client.test.ts
@@ -1262,13 +1262,13 @@ describe('orchestration service client', () => {
       expectedCacheControl: { type: string; ttl?: string }
     ): (body: any) => boolean {
       return (body: any): boolean => {
-        const messages: any[] =
+        const messageList: any[] =
           body?.messages_history ??
           body?.config?.modules?.prompt_templating?.prompt?.template;
-        if (!Array.isArray(messages) || messageIdx >= messages.length) {
+        if (!Array.isArray(messageList) || messageIdx >= messageList.length) {
           return false;
         }
-        const target = messages[messageIdx];
+        const target = messageList[messageIdx];
         if (target?.role !== 'user' || !Array.isArray(target.content)) {
           return false;
         }
@@ -1280,7 +1280,7 @@ describe('orchestration service client', () => {
           block.cache_control?.type === expectedCacheControl.type &&
           block.cache_control?.ttl === expectedCacheControl.ttl;
 
-        const otherMessagesHaveBreakpoint = messages.some(
+        const otherMessagesHaveBreakpoint = messageList.some(
           (msg: any, idx: number) =>
             idx !== messageIdx && JSON.stringify(msg).includes('cache_control')
         );

From 8dc69d79a33873d0edbe7771cc6b796bb3c5cdf6 Mon Sep 17 00:00:00 2001
From: Injun Park <injun.park@sap.com>
Date: Wed, 15 Jul 2026 10:27:50 +0200
Subject: [PATCH 33/49] Update packages/orchestration/src/util/module-config.ts

Co-authored-by: David Knaack <david.knaack@sap.com>
---
 packages/orchestration/src/util/module-config.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index c26fa9b20..c75a6d75b 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -490,7 +490,7 @@ function shouldRouteMessagesToHistory(
   }
 
   // No prompt configured — messages have nowhere to be merged into.
-  return configs.some(c => !c?.promptTemplating?.prompt);
+  return  configs.every(c => !c?.promptTemplating?.prompt);
 }
 
 function isTemplate(templating: unknown): templating is Template {

From 2f1c629717cdb27071c2dd257fdbe98bb36c7fcd Mon Sep 17 00:00:00 2001
From: "sap-ai-sdk-bot[bot]"
 <272306433+sap-ai-sdk-bot[bot]@users.noreply.github.com>
Date: Wed, 15 Jul 2026 08:28:39 +0000
Subject: [PATCH 34/49] fix: Changes from lint

---
 packages/orchestration/src/util/module-config.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index c75a6d75b..7a179a067 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -490,7 +490,7 @@ function shouldRouteMessagesToHistory(
   }
 
   // No prompt configured — messages have nowhere to be merged into.
-  return  configs.every(c => !c?.promptTemplating?.prompt);
+  return configs.every(c => !c?.promptTemplating?.prompt);
 }
 
 function isTemplate(templating: unknown): templating is Template {

From 4ee6f52b33955491ab9335cb3c1ab9fd2ef3203e Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 15 Jul 2026 11:04:28 +0200
Subject: [PATCH 35/49] fix: prevent message duplication and respect
 placeholderValues before TemplateRef check

---
 .../orchestration/src/util/module-config.ts   | 24 ++++++++++---------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 7a179a067..b6924d40a 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -388,7 +388,10 @@ export function constructCompletionPostRequest(
 
   const messagesHistory =
     routeToHistory || request?.messagesHistory?.length
-      ? [...(request?.messagesHistory || []), ...(request?.messages || [])]
+      ? [
+          ...(request?.messagesHistory || []),
+          ...(routeToHistory ? request?.messages || [] : [])
+        ]
       : undefined;
 
   return {
@@ -471,16 +474,6 @@ function shouldRouteMessagesToHistory(
   configs: OrchestrationModuleConfig[],
   request?: ChatCompletionRequest
 ): boolean {
-  // TemplateRef always routes to history — remote template cannot merge messages,
-  // regardless of placeholderValues.
-  const hasTemplateRef = configs.some(c => {
-    const prompt = c?.promptTemplating?.prompt;
-    return !!prompt && typeof prompt === 'object' && 'template_ref' in prompt;
-  });
-  if (hasTemplateRef) {
-    return true;
-  }
-
   // placeholderValues means the user opted into templating — do not route.
   if (
     !!request?.placeholderValues &&
@@ -489,6 +482,15 @@ function shouldRouteMessagesToHistory(
     return false;
   }
 
+  // TemplateRef always routes to history — remote template cannot merge messages.
+  const hasTemplateRef = configs.some(c => {
+    const prompt = c?.promptTemplating?.prompt;
+    return !!prompt && typeof prompt === 'object' && 'template_ref' in prompt;
+  });
+  if (hasTemplateRef) {
+    return true;
+  }
+
   // No prompt configured — messages have nowhere to be merged into.
   return configs.every(c => !c?.promptTemplating?.prompt);
 }

From 30286d259555580688181bf680f2cc6a3d8f4216 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 15 Jul 2026 12:58:54 +0200
Subject: [PATCH 36/49] fix: restore prompt template initialization and align
 unit tests with service behavior

---
 ...hestration-completion-post-request.test.ts | 46 +++++++++----------
 .../orchestration/src/util/module-config.ts   | 35 ++++++--------
 2 files changed, 35 insertions(+), 46 deletions(-)

diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index df7530f29..164cd8a59 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -370,27 +370,23 @@ describe('construct completion post request', () => {
         messages: [userMessage, toolMessage, followUp]
       });
 
-      expect(result.messages_history).toEqual([
-        userMessage,
-        toolMessage,
-        followUp
-      ]);
-      expect(result.config.modules.prompt_templating.prompt).toBeUndefined();
+      expect(result.messages_history).toBeUndefined();
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).toEqual([userMessage, toolMessage, followUp]);
     });
 
     it('should preserve existing messagesHistory when routing all messages', () => {
       const followUpUser = { role: 'user' as const, content: 'Follow up.' };
-      const result = constructCompletionPostRequest(noTemplateConfig, {
+      const result: any = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage, toolMessage, followUpUser],
         messagesHistory: [assistantMessage]
       });
 
-      expect(result.messages_history).toEqual([
-        assistantMessage,
-        userMessage,
-        toolMessage,
-        followUpUser
-      ]);
+      expect(result.messages_history).toEqual([assistantMessage]);
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).toEqual([userMessage, toolMessage, followUpUser]);
     });
 
     it('should route all messages to history even without tool messages', () => {
@@ -398,8 +394,10 @@ describe('construct completion post request', () => {
         messages: [userMessage]
       });
 
-      expect(result.messages_history).toEqual([userMessage]);
-      expect(result.config.modules.prompt_templating.prompt).toBeUndefined();
+      expect(result.messages_history).toBeUndefined();
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).toEqual([userMessage]);
     });
 
     it('should preserve chronological message order in messages_history', () => {
@@ -408,22 +406,22 @@ describe('construct completion post request', () => {
         messages: [userMessage, assistantMessage, toolMessage, followUpUser]
       });
 
-      expect(result.messages_history).toEqual([
-        userMessage,
-        assistantMessage,
-        toolMessage,
-        followUpUser
-      ]);
-      expect(result.config.modules.prompt_templating.prompt).toBeUndefined();
+      expect(result.messages_history).toBeUndefined();
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).toEqual([userMessage, assistantMessage, toolMessage, followUpUser]);
     });
 
     it('should combine existing messagesHistory with routed messages', () => {
-      const result = constructCompletionPostRequest(noTemplateConfig, {
+      const result: any = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage],
         messagesHistory: [assistantMessage]
       });
 
-      expect(result.messages_history).toEqual([assistantMessage, userMessage]);
+      expect(result.messages_history).toEqual([assistantMessage]);
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).toEqual([userMessage]);
     });
 
     it('should not route messages when config has a static prompt template', () => {
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index b6924d40a..9549325e0 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -420,21 +420,13 @@ function buildCompletionModulesConfig(
   };
 
   // prompt is not a string here as it is already parsed in `parseAndMergeTemplating` method
-  if (!promptTemplating.prompt) {
-    // No prompt configured: messages are already routed to messages_history upstream.
-    // Omit the prompt key entirely — it is optional per the service API.
-    const { prompt: _prompt, ...promptTemplatingWithoutPrompt } =
-      promptTemplating;
-    return {
-      prompt_templating:
-        promptTemplatingWithoutPrompt as PromptTemplatingModuleConfig,
-      ...modules
-    };
-  }
-
+  // If promptTemplating.prompt is not defined, initialize with an empty Template so the
+  // service always receives a prompt object — messages routed to messages_history upstream
+  // still need an empty template to be accepted by the Templating Module.
   const prompt: Template | TemplateRef = {
     ...(promptTemplating.prompt as Template | TemplateRef)
   };
+  promptTemplating.prompt = promptTemplating.prompt || { template: [] };
 
   if (isTemplate(prompt)) {
     if (!prompt.template?.length && !request?.messages?.length) {
@@ -474,14 +466,6 @@ function shouldRouteMessagesToHistory(
   configs: OrchestrationModuleConfig[],
   request?: ChatCompletionRequest
 ): boolean {
-  // placeholderValues means the user opted into templating — do not route.
-  if (
-    !!request?.placeholderValues &&
-    Object.keys(request.placeholderValues).length > 0
-  ) {
-    return false;
-  }
-
   // TemplateRef always routes to history — remote template cannot merge messages.
   const hasTemplateRef = configs.some(c => {
     const prompt = c?.promptTemplating?.prompt;
@@ -491,8 +475,15 @@ function shouldRouteMessagesToHistory(
     return true;
   }
 
-  // No prompt configured — messages have nowhere to be merged into.
-  return configs.every(c => !c?.promptTemplating?.prompt);
+  // placeholderValues means the user opted into templating — do not route.
+  if (
+    !!request?.placeholderValues &&
+    Object.keys(request.placeholderValues).length > 0
+  ) {
+    return false;
+  }
+
+  return false;
 }
 
 function isTemplate(templating: unknown): templating is Template {

From 2d73010b2e2ec01903689c180f1e9424e8bf116b Mon Sep 17 00:00:00 2001
From: "sap-ai-sdk-bot[bot]"
 <272306433+sap-ai-sdk-bot[bot]@users.noreply.github.com>
Date: Wed, 15 Jul 2026 11:02:09 +0000
Subject: [PATCH 37/49] fix: Changes from lint

---
 ...hestration-completion-post-request.test.ts | 37 +++++++++++--------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index 164cd8a59..3cacc6dc7 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -371,9 +371,11 @@ describe('construct completion post request', () => {
       });
 
       expect(result.messages_history).toBeUndefined();
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).toEqual([userMessage, toolMessage, followUp]);
+      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
+        userMessage,
+        toolMessage,
+        followUp
+      ]);
     });
 
     it('should preserve existing messagesHistory when routing all messages', () => {
@@ -384,9 +386,11 @@ describe('construct completion post request', () => {
       });
 
       expect(result.messages_history).toEqual([assistantMessage]);
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).toEqual([userMessage, toolMessage, followUpUser]);
+      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
+        userMessage,
+        toolMessage,
+        followUpUser
+      ]);
     });
 
     it('should route all messages to history even without tool messages', () => {
@@ -395,9 +399,9 @@ describe('construct completion post request', () => {
       });
 
       expect(result.messages_history).toBeUndefined();
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).toEqual([userMessage]);
+      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
+        userMessage
+      ]);
     });
 
     it('should preserve chronological message order in messages_history', () => {
@@ -407,9 +411,12 @@ describe('construct completion post request', () => {
       });
 
       expect(result.messages_history).toBeUndefined();
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).toEqual([userMessage, assistantMessage, toolMessage, followUpUser]);
+      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
+        userMessage,
+        assistantMessage,
+        toolMessage,
+        followUpUser
+      ]);
     });
 
     it('should combine existing messagesHistory with routed messages', () => {
@@ -419,9 +426,9 @@ describe('construct completion post request', () => {
       });
 
       expect(result.messages_history).toEqual([assistantMessage]);
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).toEqual([userMessage]);
+      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
+        userMessage
+      ]);
     });
 
     it('should not route messages when config has a static prompt template', () => {

From 4b4b4b6417ebabb557244ec0bb6d1632f079e2a2 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 15 Jul 2026 13:10:08 +0200
Subject: [PATCH 38/49] fix: restore prompt initialization order and align
 tests with service behavior

---
 packages/orchestration/src/util/module-config.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 9549325e0..fe32f31db 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -423,10 +423,10 @@ function buildCompletionModulesConfig(
   // If promptTemplating.prompt is not defined, initialize with an empty Template so the
   // service always receives a prompt object — messages routed to messages_history upstream
   // still need an empty template to be accepted by the Templating Module.
+  promptTemplating.prompt = promptTemplating.prompt || { template: [] };
   const prompt: Template | TemplateRef = {
     ...(promptTemplating.prompt as Template | TemplateRef)
   };
-  promptTemplating.prompt = promptTemplating.prompt || { template: [] };
 
   if (isTemplate(prompt)) {
     if (!prompt.template?.length && !request?.messages?.length) {

From 1320ac5ab15d7e47bee922ae93277accdb0b8868 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 15 Jul 2026 13:22:38 +0200
Subject: [PATCH 39/49] fix: allow empty messages array, only throw when
 messages is undefined

---
 packages/orchestration/src/util/module-config.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index fe32f31db..e941ef388 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -429,7 +429,7 @@ function buildCompletionModulesConfig(
   };
 
   if (isTemplate(prompt)) {
-    if (!prompt.template?.length && !request?.messages?.length) {
+    if (!prompt.template?.length && !request?.messages) {
       throw new Error('Either a prompt template or messages must be defined.');
     }
     prompt.template = [

From 2de80934d638ca3105e3cd32f7419f7373872f3e Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 15 Jul 2026 13:37:52 +0200
Subject: [PATCH 40/49] fix: use splitIndex routing to bypass templating for
 tool results

---
 ...hestration-completion-post-request.test.ts | 41 ++++++++++------
 .../orchestration/src/util/module-config.ts   | 47 ++++++++++---------
 2 files changed, 53 insertions(+), 35 deletions(-)

diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index 3cacc6dc7..17afb110f 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -357,7 +357,7 @@ describe('construct completion post request', () => {
     };
     const userMessage = { role: 'user' as const, content: 'Summarize.' };
 
-    // Config without a prompt — shouldRouteMessagesToHistory returns true
+    // Config without a prompt — messages with tool results get partial routing
     const noTemplateConfig: OrchestrationModuleConfig = {
       promptTemplating: {
         model: { name: 'gpt-5.4-nano' }
@@ -370,10 +370,9 @@ describe('construct completion post request', () => {
         messages: [userMessage, toolMessage, followUp]
       });
 
-      expect(result.messages_history).toBeUndefined();
+      // tool at index 1 → splitIndex = 2, followUp stays in template
+      expect(result.messages_history).toEqual([userMessage, toolMessage]);
       expect(result.config.modules.prompt_templating.prompt.template).toEqual([
-        userMessage,
-        toolMessage,
         followUp
       ]);
     });
@@ -385,10 +384,12 @@ describe('construct completion post request', () => {
         messagesHistory: [assistantMessage]
       });
 
-      expect(result.messages_history).toEqual([assistantMessage]);
-      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
+      expect(result.messages_history).toEqual([
+        assistantMessage,
         userMessage,
-        toolMessage,
+        toolMessage
+      ]);
+      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
         followUpUser
       ]);
     });
@@ -398,6 +399,7 @@ describe('construct completion post request', () => {
         messages: [userMessage]
       });
 
+      // no tool messages → splitIndex = 0, all go to template
       expect(result.messages_history).toBeUndefined();
       expect(result.config.modules.prompt_templating.prompt.template).toEqual([
         userMessage
@@ -410,11 +412,13 @@ describe('construct completion post request', () => {
         messages: [userMessage, assistantMessage, toolMessage, followUpUser]
       });
 
-      expect(result.messages_history).toBeUndefined();
-      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
+      // tool at index 2 → splitIndex = 3, followUpUser stays in template
+      expect(result.messages_history).toEqual([
         userMessage,
         assistantMessage,
-        toolMessage,
+        toolMessage
+      ]);
+      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
         followUpUser
       ]);
     });
@@ -425,6 +429,7 @@ describe('construct completion post request', () => {
         messagesHistory: [assistantMessage]
       });
 
+      // no tool messages → splitIndex = 0, userMessage goes to template
       expect(result.messages_history).toEqual([assistantMessage]);
       expect(result.config.modules.prompt_templating.prompt.template).toEqual([
         userMessage
@@ -436,10 +441,14 @@ describe('construct completion post request', () => {
         messages: [assistantMessage, toolMessage, userMessage]
       });
 
-      expect(result.messages_history).toBeUndefined();
+      // tool at index 1 → splitIndex = 2, userMessage stays in template
+      expect(result.messages_history).toEqual([assistantMessage, toolMessage]);
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).not.toContainEqual(toolMessage);
       expect(
         result.config.modules.prompt_templating.prompt.template
-      ).toContainEqual(toolMessage);
+      ).toContainEqual(userMessage);
     });
 
     it('should not route messages when config has prompt.tools', () => {
@@ -464,10 +473,14 @@ describe('construct completion post request', () => {
         messages: [assistantMessage, toolMessage, userMessage]
       });
 
-      expect(result.messages_history).toBeUndefined();
+      // tool at index 1 → splitIndex = 2, userMessage stays in template
+      expect(result.messages_history).toEqual([assistantMessage, toolMessage]);
+      expect(
+        result.config.modules.prompt_templating.prompt.template
+      ).not.toContainEqual(toolMessage);
       expect(
         result.config.modules.prompt_templating.prompt.template
-      ).toContainEqual(toolMessage);
+      ).toContainEqual(userMessage);
     });
   });
 });
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index e941ef388..838e3b6e8 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -11,6 +11,7 @@ import {
   type EmbeddingRequest
 } from '../orchestration-types.js';
 import type {
+  ChatMessage,
   CompletionPostRequest,
   CompletionRequestConfigurationReferenceById,
   CompletionRequestConfigurationReferenceByNameScenarioVersion,
@@ -359,12 +360,19 @@ export function constructCompletionPostRequest(
   // - Config array (OrchestrationModuleConfigList) → array of ModuleConfigs for fallback behavior
 
   const configs = Array.isArray(config) ? config : [config];
-  const routeToHistory = shouldRouteMessagesToHistory(configs, request);
+  const messages = request?.messages || [];
+  const splitIndex = getMessageSplitIndex(configs, messages, request);
+  const routeAllToHistory = splitIndex === messages.length && messages.length > 0;
 
   let moduleRequest = request;
-  if (routeToHistory && request) {
+  if (routeAllToHistory && request) {
     const { messages: _messages, ...rest } = request;
     moduleRequest = rest;
+  } else if (splitIndex > 0 && request) {
+    moduleRequest = {
+      ...request,
+      messages: messages.slice(splitIndex)
+    };
   }
 
   /**
@@ -387,10 +395,10 @@ export function constructCompletionPostRequest(
     : { modules: moduleConfigurations };
 
   const messagesHistory =
-    routeToHistory || request?.messagesHistory?.length
+    splitIndex > 0 || request?.messagesHistory?.length
       ? [
           ...(request?.messagesHistory || []),
-          ...(routeToHistory ? request?.messages || [] : [])
+          ...messages.slice(0, splitIndex)
         ]
       : undefined;
 
@@ -448,42 +456,39 @@ function buildCompletionModulesConfig(
 }
 
 /**
- * Determines whether all messages should be routed to messages_history,
- * bypassing prompt templating entirely.
- *
- * Routes to history when:
- * - no `prompt` is configured (messages have nowhere to be merged)
- * - a TemplateRef is used (remote template, messages cannot be merged in).
+ * Returns the index at which to split request.messages.
+ * Messages before the index go to messages_history (bypassing prompt templating).
+ * Messages from the index onward go to prompt.template (going through templating).
  *
- * Does NOT route to history when:
- * - a Template is set (messages are merged into prompt.template)
- * - placeholder_values are provided (user has opted into templating).
+ * Full routing (splitIndex = messages.length): TemplateRef configs — remote template, cannot merge messages in.
+ * Partial routing (splitIndex = lastToolIndex + 1): tool results may contain {{?...}} syntax from external systems.
+ * No routing (splitIndex = 0): placeholder values are set or no tool messages present.
  * @param configs - The orchestration module configurations.
+ * @param messages - The messages from the request.
  * @param request - The optional chat completion request.
- * @returns True if all messages should be routed to messages_history.
+ * @returns The split index.
  */
-function shouldRouteMessagesToHistory(
+function getMessageSplitIndex(
   configs: OrchestrationModuleConfig[],
+  messages: ChatMessage[],
   request?: ChatCompletionRequest
-): boolean {
-  // TemplateRef always routes to history — remote template cannot merge messages.
+): number {
   const hasTemplateRef = configs.some(c => {
     const prompt = c?.promptTemplating?.prompt;
     return !!prompt && typeof prompt === 'object' && 'template_ref' in prompt;
   });
   if (hasTemplateRef) {
-    return true;
+    return messages.length;
   }
 
-  // placeholderValues means the user opted into templating — do not route.
   if (
     !!request?.placeholderValues &&
     Object.keys(request.placeholderValues).length > 0
   ) {
-    return false;
+    return 0;
   }
 
-  return false;
+  return messages.findLastIndex(msg => msg.role === 'tool') + 1;
 }
 
 function isTemplate(templating: unknown): templating is Template {

From 96c2af20090d5eb6f91fbbb26b27f4c20045a138 Mon Sep 17 00:00:00 2001
From: "sap-ai-sdk-bot[bot]"
 <272306433+sap-ai-sdk-bot[bot]@users.noreply.github.com>
Date: Wed, 15 Jul 2026 11:39:03 +0000
Subject: [PATCH 41/49] fix: Changes from lint

---
 packages/orchestration/src/util/module-config.ts | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 838e3b6e8..8ebfa57de 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -362,7 +362,8 @@ export function constructCompletionPostRequest(
   const configs = Array.isArray(config) ? config : [config];
   const messages = request?.messages || [];
   const splitIndex = getMessageSplitIndex(configs, messages, request);
-  const routeAllToHistory = splitIndex === messages.length && messages.length > 0;
+  const routeAllToHistory =
+    splitIndex === messages.length && messages.length > 0;
 
   let moduleRequest = request;
   if (routeAllToHistory && request) {
@@ -396,10 +397,7 @@ export function constructCompletionPostRequest(
 
   const messagesHistory =
     splitIndex > 0 || request?.messagesHistory?.length
-      ? [
-          ...(request?.messagesHistory || []),
-          ...messages.slice(0, splitIndex)
-        ]
+      ? [...(request?.messagesHistory || []), ...messages.slice(0, splitIndex)]
       : undefined;
 
   return {

From 2f5d648ada9ce8d6bb269fed4784311b155a2aa2 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 15 Jul 2026 13:47:33 +0200
Subject: [PATCH 42/49] fix: pass empty messages array instead of removing when
 all messages are routed to history

---
 packages/orchestration/src/util/module-config.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 8ebfa57de..c89a1686a 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -367,8 +367,7 @@ export function constructCompletionPostRequest(
 
   let moduleRequest = request;
   if (routeAllToHistory && request) {
-    const { messages: _messages, ...rest } = request;
-    moduleRequest = rest;
+    moduleRequest = { ...request, messages: [] };
   } else if (splitIndex > 0 && request) {
     moduleRequest = {
       ...request,

From 831828a207ebc6e7f95869b5c439e36916a1522f Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 15 Jul 2026 14:11:50 +0200
Subject: [PATCH 43/49] fix: omit empty prompt.template when all messages are
 routed to history

---
 packages/orchestration/src/util/module-config.ts | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index c89a1686a..831cd39bc 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -437,10 +437,15 @@ function buildCompletionModulesConfig(
     if (!prompt.template?.length && !request?.messages) {
       throw new Error('Either a prompt template or messages must be defined.');
     }
-    prompt.template = [
+    const mergedTemplate = [
       ...(prompt.template || []),
       ...(request?.messages || [])
     ];
+    if (mergedTemplate.length) {
+      prompt.template = mergedTemplate;
+    } else {
+      (prompt as Record<string, unknown>).template = undefined;
+    }
   }
 
   return {

From 826f5f65a5141ce09a8cea58f982660499cc6385 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Wed, 15 Jul 2026 14:23:31 +0200
Subject: [PATCH 44/49] fix: only route to history when there are messages
 after the last tool message

---
 packages/orchestration/src/util/module-config.ts | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 831cd39bc..1d6eaa8dd 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -490,7 +490,13 @@ function getMessageSplitIndex(
     return 0;
   }
 
-  return messages.findLastIndex(msg => msg.role === 'tool') + 1;
+  const lastToolIndex = messages.findLastIndex(msg => msg.role === 'tool');
+  // Only route if there are messages after the last tool message —
+  // the service requires at least one message in prompt.template.
+  if (lastToolIndex >= 0 && lastToolIndex < messages.length - 1) {
+    return lastToolIndex + 1;
+  }
+  return 0;
 }
 
 function isTemplate(templating: unknown): templating is Template {

From 76a54cd46879773f9b2f7993c9c17d94edb706f6 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Thu, 16 Jul 2026 15:13:22 +0200
Subject: [PATCH 45/49] fix: replace splitIndex with
 shouldRouteMessagesToHistory and add tool message detection

---
 .changeset/yummy-ducks-run.md                 |  5 +-
 ...hestration-completion-post-request.test.ts | 65 ++++++------
 .../orchestration/src/orchestration-types.ts  | 11 ++-
 .../orchestration/src/util/module-config.ts   | 98 +++++++++----------
 tests/e2e-tests/src/orchestration.test.ts     |  4 +-
 5 files changed, 88 insertions(+), 95 deletions(-)

diff --git a/.changeset/yummy-ducks-run.md b/.changeset/yummy-ducks-run.md
index 5966f6790..199406e34 100644
--- a/.changeset/yummy-ducks-run.md
+++ b/.changeset/yummy-ducks-run.md
@@ -2,6 +2,5 @@
 '@sap-ai-sdk/orchestration': patch
 ---
 
-[Fix] Automatically route all `messages` to `messages_history` to bypass prompt templating when no `prompt` is configured or a `TemplateRef` is used.
-Routing is skipped when a `Template` is configured or `placeholderValues` are provided.
-
+[Fix] Automatically route `messages` to `messages_history` to bypass prompt templating when tool results are present (preventing `{{?...}}` syntax in tool content from being interpreted as template placeholders), a `TemplateRef` is used, or no `prompt` is configured.
+Routing is skipped when `placeholderValues` are provided.
diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index 17afb110f..f6b8e6e51 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -357,24 +357,21 @@ describe('construct completion post request', () => {
     };
     const userMessage = { role: 'user' as const, content: 'Summarize.' };
 
-    // Config without a prompt — messages with tool results get partial routing
+    // Config without a prompt — tool messages trigger full routing to messages_history
     const noTemplateConfig: OrchestrationModuleConfig = {
       promptTemplating: {
         model: { name: 'gpt-5.4-nano' }
       }
     };
 
-    it('should route all messages to messages_history when no prompt is configured', () => {
+    it('should route all messages to messages_history when tool message is present', () => {
       const followUp = { role: 'user' as const, content: 'Follow up.' };
       const result: any = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage, toolMessage, followUp]
       });
 
-      // tool at index 1 → splitIndex = 2, followUp stays in template
-      expect(result.messages_history).toEqual([userMessage, toolMessage]);
-      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
-        followUp
-      ]);
+      expect(result.messages_history).toEqual([userMessage, toolMessage, followUp]);
+      expect(result.config.modules.prompt_templating.prompt).toBeUndefined();
     });
 
     it('should preserve existing messagesHistory when routing all messages', () => {
@@ -387,38 +384,32 @@ describe('construct completion post request', () => {
       expect(result.messages_history).toEqual([
         assistantMessage,
         userMessage,
-        toolMessage
-      ]);
-      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
+        toolMessage,
         followUpUser
       ]);
     });
 
-    it('should route all messages to history even without tool messages', () => {
+    it('should not route messages when no tool messages are present', () => {
       const result: any = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage]
       });
 
-      // no tool messages → splitIndex = 0, all go to template
+      // no tool messages → no routing, userMessage merged into prompt.template
       expect(result.messages_history).toBeUndefined();
       expect(result.config.modules.prompt_templating.prompt.template).toEqual([
         userMessage
       ]);
     });
-
-    it('should preserve chronological message order in messages_history', () => {
+    it('should preserve chronological message order when routing to messages_history', () => {
       const followUpUser = { role: 'user' as const, content: 'Follow up.' };
       const result: any = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage, assistantMessage, toolMessage, followUpUser]
       });
 
-      // tool at index 2 → splitIndex = 3, followUpUser stays in template
       expect(result.messages_history).toEqual([
         userMessage,
         assistantMessage,
-        toolMessage
-      ]);
-      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
+        toolMessage,
         followUpUser
       ]);
     });
@@ -429,29 +420,30 @@ describe('construct completion post request', () => {
         messagesHistory: [assistantMessage]
       });
 
-      // no tool messages → splitIndex = 0, userMessage goes to template
+      // no tool messages → no routing, userMessage merged into prompt.template
       expect(result.messages_history).toEqual([assistantMessage]);
       expect(result.config.modules.prompt_templating.prompt.template).toEqual([
         userMessage
       ]);
     });
 
-    it('should not route messages when config has a static prompt template', () => {
+    it('should route all messages when tool message present with static prompt template', () => {
       const result: any = constructCompletionPostRequest(defaultConfig, {
         messages: [assistantMessage, toolMessage, userMessage]
       });
 
-      // tool at index 1 → splitIndex = 2, userMessage stays in template
-      expect(result.messages_history).toEqual([assistantMessage, toolMessage]);
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).not.toContainEqual(toolMessage);
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).toContainEqual(userMessage);
+      expect(result.messages_history).toEqual([
+        assistantMessage,
+        toolMessage,
+        userMessage
+      ]);
+      // static template remains, messages were removed (routed to history)
+      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
+        { role: 'user', content: 'Hi' }
+      ]);
     });
 
-    it('should not route messages when config has prompt.tools', () => {
+    it('should route all messages when tool message present with prompt.tools config', () => {
       const toolsConfig: OrchestrationModuleConfig = {
         promptTemplating: {
           model: { name: 'gpt-5.4-nano' },
@@ -473,14 +465,13 @@ describe('construct completion post request', () => {
         messages: [assistantMessage, toolMessage, userMessage]
       });
 
-      // tool at index 1 → splitIndex = 2, userMessage stays in template
-      expect(result.messages_history).toEqual([assistantMessage, toolMessage]);
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).not.toContainEqual(toolMessage);
-      expect(
-        result.config.modules.prompt_templating.prompt.template
-      ).toContainEqual(userMessage);
+      expect(result.messages_history).toEqual([
+        assistantMessage,
+        toolMessage,
+        userMessage
+      ]);
+      // tools config: messages removed, prompt.template omitted when empty
+      expect(result.config.modules.prompt_templating.prompt.template).toBeUndefined();
     });
   });
 });
diff --git a/packages/orchestration/src/orchestration-types.ts b/packages/orchestration/src/orchestration-types.ts
index cb7928039..e142bc170 100644
--- a/packages/orchestration/src/orchestration-types.ts
+++ b/packages/orchestration/src/orchestration-types.ts
@@ -46,10 +46,13 @@ export interface ChatCompletionRequest {
 
   /**
    * New chat messages, including template messages.
-   * All messages are automatically routed to `messages_history` when no `prompt` is configured
-   * or a `TemplateRef` is used, bypassing prompt templating entirely.
-   * When a `Template` is configured, messages are merged into `prompt.template` as usual.
-   * Routing is skipped when `placeholderValues` are provided.
+   * Messages are automatically routed to `messages_history` (bypassing prompt templating) when:
+   * - tool results are present (`role: 'tool'`) — prevents `{{?...}}` syntax in tool content
+   *   from being misinterpreted as template placeholders
+   * - a `TemplateRef` is used (remote template, cannot merge messages in)
+   * - no `prompt` is configured
+   *
+   * Routing is skipped when `placeholderValues` are provided (user has opted into templating).
    * To verify the final message order sent to the LLM, use
    * `response.getIntermediateResults().templating`.
    * @example
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 1d6eaa8dd..6050e64a1 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -11,7 +11,6 @@ import {
   type EmbeddingRequest
 } from '../orchestration-types.js';
 import type {
-  ChatMessage,
   CompletionPostRequest,
   CompletionRequestConfigurationReferenceById,
   CompletionRequestConfigurationReferenceByNameScenarioVersion,
@@ -360,20 +359,12 @@ export function constructCompletionPostRequest(
   // - Config array (OrchestrationModuleConfigList) → array of ModuleConfigs for fallback behavior
 
   const configs = Array.isArray(config) ? config : [config];
-  const messages = request?.messages || [];
-  const splitIndex = getMessageSplitIndex(configs, messages, request);
-  const routeAllToHistory =
-    splitIndex === messages.length && messages.length > 0;
-
-  let moduleRequest = request;
-  if (routeAllToHistory && request) {
-    moduleRequest = { ...request, messages: [] };
-  } else if (splitIndex > 0 && request) {
-    moduleRequest = {
-      ...request,
-      messages: messages.slice(splitIndex)
-    };
-  }
+  const routeToHistory = shouldRouteMessagesToHistory(configs, request);
+
+  const moduleRequest =
+    routeToHistory && request
+      ? { ...request, messages: undefined }
+      : request;
 
   /**
    * Module configurations for the orchestration request.
@@ -394,10 +385,12 @@ export function constructCompletionPostRequest(
         )
     : { modules: moduleConfigurations };
 
+  // Only append messages when routing is active to avoid duplicating messages
+  // already present in messagesHistory.
   const messagesHistory =
-    splitIndex > 0 || request?.messagesHistory?.length
-      ? [...(request?.messagesHistory || []), ...messages.slice(0, splitIndex)]
-      : undefined;
+    routeToHistory && request?.messages?.length
+      ? [...(request.messagesHistory || []), ...request.messages]
+      : request?.messagesHistory;
 
   return {
     config: configWithStream,
@@ -425,16 +418,24 @@ function buildCompletionModulesConfig(
   };
 
   // prompt is not a string here as it is already parsed in `parseAndMergeTemplating` method
-  // If promptTemplating.prompt is not defined, initialize with an empty Template so the
-  // service always receives a prompt object — messages routed to messages_history upstream
-  // still need an empty template to be accepted by the Templating Module.
+  // If promptTemplating.prompt is not defined and messages were routed upstream,
+  // omit the prompt key entirely so the service receives only messages_history.
+  if (!promptTemplating.prompt && request?.messages === undefined) {
+    const { prompt: _prompt, ...rest } = promptTemplating;
+    return {
+      prompt_templating: rest as PromptTemplatingModuleConfig,
+      ...modules
+    };
+  }
+
+  // If promptTemplating.prompt is not defined, we initialize it with an empty Template object
   promptTemplating.prompt = promptTemplating.prompt || { template: [] };
-  const prompt: Template | TemplateRef = {
+  const prompt = {
     ...(promptTemplating.prompt as Template | TemplateRef)
   };
 
   if (isTemplate(prompt)) {
-    if (!prompt.template?.length && !request?.messages) {
+    if (!prompt.template?.length && !request) {
       throw new Error('Either a prompt template or messages must be defined.');
     }
     const mergedTemplate = [
@@ -444,7 +445,7 @@ function buildCompletionModulesConfig(
     if (mergedTemplate.length) {
       prompt.template = mergedTemplate;
     } else {
-      (prompt as Record<string, unknown>).template = undefined;
+      delete (prompt as Partial<typeof prompt>).template;
     }
   }
 
@@ -458,45 +459,34 @@ function buildCompletionModulesConfig(
 }
 
 /**
- * Returns the index at which to split request.messages.
- * Messages before the index go to messages_history (bypassing prompt templating).
- * Messages from the index onward go to prompt.template (going through templating).
+ * Determines whether all messages should be routed to messages_history,
+ * bypassing prompt templating entirely.
+ *
+ * Routes when:
+ * - a TemplateRef is used (remote template, cannot merge messages in)
+ * - messages contain tool results (content may include {{?...}} syntax from external systems).
  *
- * Full routing (splitIndex = messages.length): TemplateRef configs — remote template, cannot merge messages in.
- * Partial routing (splitIndex = lastToolIndex + 1): tool results may contain {{?...}} syntax from external systems.
- * No routing (splitIndex = 0): placeholder values are set or no tool messages present.
+ * Does NOT route when placeholder values are provided (user opted into templating).
  * @param configs - The orchestration module configurations.
- * @param messages - The messages from the request.
  * @param request - The optional chat completion request.
- * @returns The split index.
+ * @returns True if messages should be routed to messages_history.
  */
-function getMessageSplitIndex(
+function shouldRouteMessagesToHistory(
   configs: OrchestrationModuleConfig[],
-  messages: ChatMessage[],
   request?: ChatCompletionRequest
-): number {
-  const hasTemplateRef = configs.some(c => {
-    const prompt = c?.promptTemplating?.prompt;
-    return !!prompt && typeof prompt === 'object' && 'template_ref' in prompt;
-  });
-  if (hasTemplateRef) {
-    return messages.length;
-  }
-
+): boolean {
   if (
     !!request?.placeholderValues &&
     Object.keys(request.placeholderValues).length > 0
   ) {
-    return 0;
+    return false;
   }
 
-  const lastToolIndex = messages.findLastIndex(msg => msg.role === 'tool');
-  // Only route if there are messages after the last tool message —
-  // the service requires at least one message in prompt.template.
-  if (lastToolIndex >= 0 && lastToolIndex < messages.length - 1) {
-    return lastToolIndex + 1;
+  if (configs.some(c => isTemplateRef(c?.promptTemplating?.prompt || {}))) {
+    return true;
   }
-  return 0;
+
+  return !!request?.messages?.some(m => m.role === 'tool');
 }
 
 function isTemplate(templating: unknown): templating is Template {
@@ -507,6 +497,14 @@ function isTemplate(templating: unknown): templating is Template {
   );
 }
 
+function isTemplateRef(templating: unknown): templating is TemplateRef {
+  return (
+    !!templating &&
+    typeof templating === 'object' &&
+    'template_ref' in templating
+  );
+}
+
 /**
  * Constructs an embedding post request from the given configuration and request.
  * @internal
diff --git a/tests/e2e-tests/src/orchestration.test.ts b/tests/e2e-tests/src/orchestration.test.ts
index f4b57f411..4229f08a2 100644
--- a/tests/e2e-tests/src/orchestration.test.ts
+++ b/tests/e2e-tests/src/orchestration.test.ts
@@ -343,7 +343,9 @@ describe('orchestration', () => {
 
       const templating = response.getIntermediateResults().templating;
       const roles = templating!.map(m => m.role);
-      expect(roles).toEqual(['assistant', 'tool', 'user']);
+      expect(roles).toContain('tool');
+      expect(roles).toContain('user');
+      expect(roles.lastIndexOf('tool')).toBeLessThan(roles.lastIndexOf('user'));
     });
 
     it('should apply masking to tool results automatically routed to messages_history', async () => {

From a2a10e0abf89b421e1e95242ed4aa63fcc20e805 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Thu, 16 Jul 2026 15:37:07 +0200
Subject: [PATCH 46/49] fix: fix JSDoc indentation and skip routing when
 prompt.tools is present

---
 ...rchestration-completion-post-request.test.ts | 14 +++++++++-----
 .../orchestration/src/orchestration-types.ts    | 13 ++++---------
 .../orchestration/src/util/module-config.ts     | 17 +++++++++++++----
 3 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index f6b8e6e51..5608cb556 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -370,7 +370,11 @@ describe('construct completion post request', () => {
         messages: [userMessage, toolMessage, followUp]
       });
 
-      expect(result.messages_history).toEqual([userMessage, toolMessage, followUp]);
+      expect(result.messages_history).toEqual([
+        userMessage,
+        toolMessage,
+        followUp
+      ]);
       expect(result.config.modules.prompt_templating.prompt).toBeUndefined();
     });
 
@@ -443,7 +447,7 @@ describe('construct completion post request', () => {
       ]);
     });
 
-    it('should route all messages when tool message present with prompt.tools config', () => {
+    it('should not route messages when config has prompt.tools (service requires template alongside tools)', () => {
       const toolsConfig: OrchestrationModuleConfig = {
         promptTemplating: {
           model: { name: 'gpt-5.4-nano' },
@@ -465,13 +469,13 @@ describe('construct completion post request', () => {
         messages: [assistantMessage, toolMessage, userMessage]
       });
 
-      expect(result.messages_history).toEqual([
+      // prompt.tools present → routing skipped, messages merged into template
+      expect(result.messages_history).toBeUndefined();
+      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
         assistantMessage,
         toolMessage,
         userMessage
       ]);
-      // tools config: messages removed, prompt.template omitted when empty
-      expect(result.config.modules.prompt_templating.prompt.template).toBeUndefined();
     });
   });
 });
diff --git a/packages/orchestration/src/orchestration-types.ts b/packages/orchestration/src/orchestration-types.ts
index e142bc170..4f044f22e 100644
--- a/packages/orchestration/src/orchestration-types.ts
+++ b/packages/orchestration/src/orchestration-types.ts
@@ -46,15 +46,10 @@ export interface ChatCompletionRequest {
 
   /**
    * New chat messages, including template messages.
-   * Messages are automatically routed to `messages_history` (bypassing prompt templating) when:
-   * - tool results are present (`role: 'tool'`) — prevents `{{?...}}` syntax in tool content
-   *   from being misinterpreted as template placeholders
-   * - a `TemplateRef` is used (remote template, cannot merge messages in)
-   * - no `prompt` is configured
-   *
-   * Routing is skipped when `placeholderValues` are provided (user has opted into templating).
-   * To verify the final message order sent to the LLM, use
-   * `response.getIntermediateResults().templating`.
+   * Messages are automatically routed to `messages_history` (bypassing prompt templating) when tool results are present (`role: 'tool'`),
+   * a `TemplateRef` is used, or no `prompt` is configured.
+   * Routing is skipped when `placeholderValues` are provided.
+   * To verify the final message order sent to the LLM, use `response.getIntermediateResults().templating`.
    * @example
    * messages: [
    *   {
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 6050e64a1..4ea6ade92 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -362,9 +362,7 @@ export function constructCompletionPostRequest(
   const routeToHistory = shouldRouteMessagesToHistory(configs, request);
 
   const moduleRequest =
-    routeToHistory && request
-      ? { ...request, messages: undefined }
-      : request;
+    routeToHistory && request ? { ...request, messages: undefined } : request;
 
   /**
    * Module configurations for the orchestration request.
@@ -445,7 +443,7 @@ function buildCompletionModulesConfig(
     if (mergedTemplate.length) {
       prompt.template = mergedTemplate;
     } else {
-      delete (prompt as Partial<typeof prompt>).template;
+      prompt.template = [];
     }
   }
 
@@ -486,6 +484,17 @@ function shouldRouteMessagesToHistory(
     return true;
   }
 
+  // Skip routing when any config has prompt.tools — the service requires template
+  // to be present alongside tools, so routing would strip messages and break the request.
+  if (
+    configs.some(c => {
+      const prompt = c?.promptTemplating?.prompt;
+      return isTemplate(prompt) && !!(prompt as { tools?: unknown }).tools;
+    })
+  ) {
+    return false;
+  }
+
   return !!request?.messages?.some(m => m.role === 'tool');
 }
 

From cce280bebf3fb4a1256d03ebe3e1607eff1609a8 Mon Sep 17 00:00:00 2001
From: Injun Park <injun.park@sap.com>
Date: Fri, 17 Jul 2026 14:19:25 +0200
Subject: [PATCH 47/49] Apply suggestions from code review

Co-authored-by: David Knaack <david.knaack@sap.com>
---
 packages/orchestration/src/util/module-config.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 4ea6ade92..448b0d18d 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -489,13 +489,13 @@ function shouldRouteMessagesToHistory(
   if (
     configs.some(c => {
       const prompt = c?.promptTemplating?.prompt;
-      return isTemplate(prompt) && !!(prompt as { tools?: unknown }).tools;
+      return isTemplate(prompt) || !!(prompt as { tools?: unknown }).tools;
     })
   ) {
     return false;
   }
 
-  return !!request?.messages?.some(m => m.role === 'tool');
+  return true;
 }
 
 function isTemplate(templating: unknown): templating is Template {

From 73d0fdd9aa321e2b5dff3cd803270da1c6e613d2 Mon Sep 17 00:00:00 2001
From: InjunPark-sap <injun.park@sap.com>
Date: Fri, 17 Jul 2026 14:37:23 +0200
Subject: [PATCH 48/49] apply feedbacks

---
 .changeset/yummy-ducks-run.md                 |  4 +--
 ...hestration-completion-post-request.test.ts | 28 ++++++++-----------
 .../orchestration/src/util/module-config.ts   | 15 +++++-----
 tsconfig.base.json                            |  4 +--
 4 files changed, 22 insertions(+), 29 deletions(-)

diff --git a/.changeset/yummy-ducks-run.md b/.changeset/yummy-ducks-run.md
index 199406e34..ab36c755f 100644
--- a/.changeset/yummy-ducks-run.md
+++ b/.changeset/yummy-ducks-run.md
@@ -2,5 +2,5 @@
 '@sap-ai-sdk/orchestration': patch
 ---
 
-[Fix] Automatically route `messages` to `messages_history` to bypass prompt templating when tool results are present (preventing `{{?...}}` syntax in tool content from being interpreted as template placeholders), a `TemplateRef` is used, or no `prompt` is configured.
-Routing is skipped when `placeholderValues` are provided.
+[Fix] Automatically route `messages` to `messages_history` to bypass prompt templating when no `prompt` is configured or a `TemplateRef` is used.
+Routing is skipped when `placeholderValues` are provided or a prompt with `template` or `tools` is set.
diff --git a/packages/orchestration/src/orchestration-completion-post-request.test.ts b/packages/orchestration/src/orchestration-completion-post-request.test.ts
index 5608cb556..5b3a8f328 100644
--- a/packages/orchestration/src/orchestration-completion-post-request.test.ts
+++ b/packages/orchestration/src/orchestration-completion-post-request.test.ts
@@ -393,16 +393,14 @@ describe('construct completion post request', () => {
       ]);
     });
 
-    it('should not route messages when no tool messages are present', () => {
+    it('should route messages when no prompt is configured (even without tool messages)', () => {
       const result: any = constructCompletionPostRequest(noTemplateConfig, {
         messages: [userMessage]
       });
 
-      // no tool messages → no routing, userMessage merged into prompt.template
-      expect(result.messages_history).toBeUndefined();
-      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
-        userMessage
-      ]);
+      // no prompt → always route to messages_history
+      expect(result.messages_history).toEqual([userMessage]);
+      expect(result.config.modules.prompt_templating.prompt).toBeUndefined();
     });
     it('should preserve chronological message order when routing to messages_history', () => {
       const followUpUser = { role: 'user' as const, content: 'Follow up.' };
@@ -424,27 +422,23 @@ describe('construct completion post request', () => {
         messagesHistory: [assistantMessage]
       });
 
-      // no tool messages → no routing, userMessage merged into prompt.template
-      expect(result.messages_history).toEqual([assistantMessage]);
-      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
-        userMessage
-      ]);
+      // no prompt → always route, prepended to existing messagesHistory
+      expect(result.messages_history).toEqual([assistantMessage, userMessage]);
     });
 
-    it('should route all messages when tool message present with static prompt template', () => {
+    it('should not route messages when config has a static prompt template', () => {
       const result: any = constructCompletionPostRequest(defaultConfig, {
         messages: [assistantMessage, toolMessage, userMessage]
       });
 
-      expect(result.messages_history).toEqual([
+      // prompt.template present → no routing, messages merged into template
+      expect(result.messages_history).toBeUndefined();
+      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
+        { role: 'user', content: 'Hi' },
         assistantMessage,
         toolMessage,
         userMessage
       ]);
-      // static template remains, messages were removed (routed to history)
-      expect(result.config.modules.prompt_templating.prompt.template).toEqual([
-        { role: 'user', content: 'Hi' }
-      ]);
     });
 
     it('should not route messages when config has prompt.tools (service requires template alongside tools)', () => {
diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 448b0d18d..0cb96afaf 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -473,6 +473,10 @@ function shouldRouteMessagesToHistory(
   configs: OrchestrationModuleConfig[],
   request?: ChatCompletionRequest
 ): boolean {
+  if (configs.some(c => isTemplateRef(c?.promptTemplating?.prompt || {}))) {
+    return true;
+  }
+
   if (
     !!request?.placeholderValues &&
     Object.keys(request.placeholderValues).length > 0
@@ -480,16 +484,13 @@ function shouldRouteMessagesToHistory(
     return false;
   }
 
-  if (configs.some(c => isTemplateRef(c?.promptTemplating?.prompt || {}))) {
-    return true;
-  }
-
-  // Skip routing when any config has prompt.tools — the service requires template
-  // to be present alongside tools, so routing would strip messages and break the request.
+  // Skip routing when any config has a prompt with template or tools set.
+  // The service requires template to be present alongside tools,
+  // so routing would strip messages and break the request.
   if (
     configs.some(c => {
       const prompt = c?.promptTemplating?.prompt;
-      return isTemplate(prompt) || !!(prompt as { tools?: unknown }).tools;
+      return !!prompt && (isTemplate(prompt) || !!(prompt as { tools?: unknown }).tools);
     })
   ) {
     return false;
diff --git a/tsconfig.base.json b/tsconfig.base.json
index 1f5177363..b0d51ad4e 100644
--- a/tsconfig.base.json
+++ b/tsconfig.base.json
@@ -1,7 +1,6 @@
 {
   "compilerOptions": {
-    "target": "ES2022",
-    "lib": ["es2023"],
+    "target": "ES2024",
     "module": "Node16",
     "declaration": true,
     "declarationMap": true,
@@ -11,7 +10,6 @@
     "strict": true,
     "skipLibCheck": true,
     "isolatedModules": true,
-    "lib": ["es2024"],
     "types": ["node"]
   }
 }

From 8de127f68c7437251700265d452b91c94c1ddbfe Mon Sep 17 00:00:00 2001
From: "sap-ai-sdk-bot[bot]"
 <272306433+sap-ai-sdk-bot[bot]@users.noreply.github.com>
Date: Fri, 17 Jul 2026 12:38:32 +0000
Subject: [PATCH 49/49] fix: Changes from generation

---
 packages/orchestration/src/util/module-config.ts | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/orchestration/src/util/module-config.ts b/packages/orchestration/src/util/module-config.ts
index 0cb96afaf..1c923c3aa 100644
--- a/packages/orchestration/src/util/module-config.ts
+++ b/packages/orchestration/src/util/module-config.ts
@@ -490,7 +490,10 @@ function shouldRouteMessagesToHistory(
   if (
     configs.some(c => {
       const prompt = c?.promptTemplating?.prompt;
-      return !!prompt && (isTemplate(prompt) || !!(prompt as { tools?: unknown }).tools);
+      return (
+        !!prompt &&
+        (isTemplate(prompt) || !!(prompt as { tools?: unknown }).tools)
+      );
     })
   ) {
     return false;