From 43153a12e0d8bca58349714d962aeca5254741fa Mon Sep 17 00:00:00 2001
From: Zamil Majdy <zamil.majdy@agpt.co>
Date: Tue, 10 Feb 2026 13:52:49 +0400
Subject: [PATCH] fix(backend/chat): Remove manual context truncation from SDK
 path, let SDK handle compaction

---
 .../backend/api/features/chat/config.py       |  6 ++---
 .../backend/api/features/chat/sdk/service.py  | 22 +++++++------------
 2 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/autogpt_platform/backend/backend/api/features/chat/config.py b/autogpt_platform/backend/backend/api/features/chat/config.py
index 223ea8f336..dfa4608ba4 100644
--- a/autogpt_platform/backend/backend/api/features/chat/config.py
+++ b/autogpt_platform/backend/backend/api/features/chat/config.py
@@ -27,13 +27,13 @@ class ChatConfig(BaseSettings):
     session_ttl: int = Field(default=43200, description="Session TTL in seconds")
 
     # Streaming Configuration
-    # Note: When using Claude Agent SDK, context management is handled automatically
-    # via the SDK's built-in compaction. This is mainly used for the fallback path.
+    # Only used by the non-SDK fallback path (Anthropic direct).
+    # The SDK path passes full history and relies on SDK's built-in compaction.
     max_context_messages: int = Field(
         default=100,
         ge=1,
         le=500,
-        description="Max context messages (SDK handles compaction automatically)",
+        description="Max context messages for non-SDK fallback path only",
     )
 
     stream_timeout: int = Field(default=300, description="Stream timeout in seconds")
diff --git a/autogpt_platform/backend/backend/api/features/chat/sdk/service.py b/autogpt_platform/backend/backend/api/features/chat/sdk/service.py
index 2446b2a932..722eb8a814 100644
--- a/autogpt_platform/backend/backend/api/features/chat/sdk/service.py
+++ b/autogpt_platform/backend/backend/api/features/chat/sdk/service.py
@@ -142,8 +142,8 @@ async def _build_system_prompt(
 def _format_conversation_history(session: ChatSession) -> str:
     """Format conversation history as a prompt context.
 
-    The SDK handles context compaction automatically, but we apply
-    max_context_messages as a safety guard to limit initial prompt size.
+    Passes full history to the SDK — the SDK handles context compaction
+    automatically when the context window approaches its limit.
     """
     if not session.messages:
         return ""
@@ -153,19 +153,12 @@ def _format_conversation_history(session: ChatSession) -> str:
     if not messages:
         return ""
 
-    # Apply max_context_messages limit as a safety guard
-    # (SDK handles compaction, but this prevents excessively large initial prompts)
-    max_messages = config.max_context_messages
-    if len(messages) > max_messages:
-        messages = messages[-max_messages:]
-
     history_parts = ["<conversation_history>"]
 
     for msg in messages:
         if msg.role == "user":
             history_parts.append(f"User: {msg.content or ''}")
         elif msg.role == "assistant":
-            # Pass full content - SDK handles compaction automatically
             history_parts.append(f"Assistant: {msg.content or ''}")
             if msg.tool_calls:
                 for tc in msg.tool_calls:
@@ -174,11 +167,7 @@ def _format_conversation_history(session: ChatSession) -> str:
                         f"  [Called tool: {func.get('name', 'unknown')}]"
                     )
         elif msg.role == "tool":
-            # Truncate large tool results to avoid blowing context window
-            tool_content = msg.content or ""
-            if len(tool_content) > 500:
-                tool_content = tool_content[:500] + "... (truncated)"
-            history_parts.append(f"  [Tool result: {tool_content}]")
+            history_parts.append(f"  [Tool result: {msg.content or ''}]")
 
     history_parts.append("</conversation_history>")
     history_parts.append("")
@@ -333,6 +322,11 @@ async def stream_chat_completion_sdk(
                 else:
                     prompt = current_message
 
+                logger.info(
+                    f"[SDK] Prompt built: {len(prompt)} chars, "
+                    f"{len(session.messages)} messages in session"
+                )
+
                 # Guard against empty prompts
                 if not prompt.strip():
                     yield StreamError(