fix: ruff

.gitignore

@@ -2,6 +2,7 @@
 __pycache__/
 *.py[cod]
 *$py.class
+experiments/
 
 experiments
 # C extensions

application/agents/base.py

@@ -34,6 +34,7 @@ class BaseAgent(ABC):
         token_limit: Optional[int] = settings.DEFAULT_AGENT_LIMITS["token_limit"],
         limited_request_mode: Optional[bool] = False,
         request_limit: Optional[int] = settings.DEFAULT_AGENT_LIMITS["request_limit"],
+        compressed_summary: Optional[str] = None,
     ):
         self.endpoint = endpoint
         self.llm_name = llm_name
@@ -64,6 +65,9 @@ class BaseAgent(ABC):
         self.token_limit = token_limit
         self.limited_request_mode = limited_request_mode
         self.request_limit = request_limit
+        self.compressed_summary = compressed_summary
+        self.current_token_count = 0
+        self.context_limit_reached = False
 
     @log_activity()
     def gen(
@@ -276,12 +280,77 @@ class BaseAgent(ABC):
             for tool_call in self.tool_calls
         ]
 
+    def _calculate_current_context_tokens(self, messages: List[Dict]) -> int:
+        """
+        Calculate total tokens in current context (messages).
+
+        Args:
+            messages: List of message dicts
+
+        Returns:
+            Total token count
+        """
+        from application.api.answer.services.compression.token_counter import (
+            TokenCounter,
+        )
+
+        return TokenCounter.count_message_tokens(messages)
+
+    def _check_context_limit(self, messages: List[Dict]) -> bool:
+        """
+        Check if we're approaching context limit (80%).
+
+        Args:
+            messages: Current message list
+
+        Returns:
+            True if at or above 80% of context limit
+        """
+        from application.core.model_utils import get_token_limit
+        from application.core.settings import settings
+
+        try:
+            # Calculate current tokens
+            current_tokens = self._calculate_current_context_tokens(messages)
+            self.current_token_count = current_tokens
+
+            # Get context limit for model
+            context_limit = get_token_limit(self.model_id)
+
+            # Calculate threshold (80%)
+            threshold = int(context_limit * settings.COMPRESSION_THRESHOLD_PERCENTAGE)
+
+            # Check if we've reached the limit
+            if current_tokens >= threshold:
+                logger.warning(
+                    f"Context limit approaching: {current_tokens}/{context_limit} tokens "
+                    f"({(current_tokens/context_limit)*100:.1f}%)"
+                )
+                return True
+
+            return False
+
+        except Exception as e:
+            logger.error(f"Error checking context limit: {str(e)}", exc_info=True)
+            return False
+
     def _build_messages(
         self,
         system_prompt: str,
         query: str,
     ) -> List[Dict]:
         """Build messages using pre-rendered system prompt"""
+        # Append compression summary to system prompt if present
+        if self.compressed_summary:
+            compression_context = (
+                "\n\n---\n\n"
+                "This session is being continued from a previous conversation that "
+                "has been compressed to fit within context limits. "
+                "The conversation is summarized below:\n\n"
+                f"{self.compressed_summary}"
+            )
+            system_prompt = system_prompt + compression_context
+
         messages = [{"role": "system", "content": system_prompt}]
 
         for i in self.chat_history:

application/api/answer/routes/base.py

@@ -266,6 +266,26 @@ class BaseAnswerResource:
                     shared_token=shared_token,
                     attachment_ids=attachment_ids,
                 )
+                # Persist compression metadata/summary if it exists and wasn't saved mid-execution
+                compression_meta = getattr(agent, "compression_metadata", None)
+                compression_saved = getattr(agent, "compression_saved", False)
+                if conversation_id and compression_meta and not compression_saved:
+                    try:
+                        self.conversation_service.update_compression_metadata(
+                            conversation_id, compression_meta
+                        )
+                        self.conversation_service.append_compression_message(
+                            conversation_id, compression_meta
+                        )
+                        agent.compression_saved = True
+                        logger.info(
+                            f"Persisted compression metadata for conversation {conversation_id}"
+                        )
+                    except Exception as e:
+                        logger.error(
+                            f"Failed to persist compression metadata: {str(e)}",
+                            exc_info=True,
+                        )
             else:
                 conversation_id = None
             id_data = {"type": "id", "id": str(conversation_id)}
@@ -328,6 +348,25 @@ class BaseAnswerResource:
                         shared_token=shared_token,
                         attachment_ids=attachment_ids,
                     )
+                    compression_meta = getattr(agent, "compression_metadata", None)
+                    compression_saved = getattr(agent, "compression_saved", False)
+                    if conversation_id and compression_meta and not compression_saved:
+                        try:
+                            self.conversation_service.update_compression_metadata(
+                                conversation_id, compression_meta
+                            )
+                            self.conversation_service.append_compression_message(
+                                conversation_id, compression_meta
+                            )
+                            agent.compression_saved = True
+                            logger.info(
+                                f"Persisted compression metadata for conversation {conversation_id} (partial stream)"
+                            )
+                        except Exception as e:
+                            logger.error(
+                                f"Failed to persist compression metadata (partial stream): {str(e)}",
+                                exc_info=True,
+                            )
                 except Exception as e:
                     logger.error(
                         f"Error saving partial response: {str(e)}", exc_info=True

application/api/answer/services/compression/__init__.py

@@ -0,0 +1,20 @@
+"""
+Compression module for managing conversation context compression.
+
+"""
+
+from application.api.answer.services.compression.orchestrator import (
+    CompressionOrchestrator,
+)
+from application.api.answer.services.compression.service import CompressionService
+from application.api.answer.services.compression.types import (
+    CompressionResult,
+    CompressionMetadata,
+)
+
+__all__ = [
+    "CompressionOrchestrator",
+    "CompressionService",
+    "CompressionResult",
+    "CompressionMetadata",
+]

application/api/answer/services/compression/message_builder.py

@@ -0,0 +1,234 @@
+"""Message reconstruction utilities for compression."""
+
+import logging
+import uuid
+from typing import Dict, List, Optional
+
+logger = logging.getLogger(__name__)
+
+
+class MessageBuilder:
+    """Builds message arrays from compressed context."""
+
+    @staticmethod
+    def build_from_compressed_context(
+        system_prompt: str,
+        compressed_summary: Optional[str],
+        recent_queries: List[Dict],
+        include_tool_calls: bool = False,
+        context_type: str = "pre_request",
+    ) -> List[Dict]:
+        """
+        Build messages from compressed context.
+
+        Args:
+            system_prompt: Original system prompt
+            compressed_summary: Compressed summary (if any)
+            recent_queries: Recent uncompressed queries
+            include_tool_calls: Whether to include tool calls from history
+            context_type: Type of context ('pre_request' or 'mid_execution')
+
+        Returns:
+            List of message dicts ready for LLM
+        """
+        # Append compression summary to system prompt if present
+        if compressed_summary:
+            system_prompt = MessageBuilder._append_compression_context(
+                system_prompt, compressed_summary, context_type
+            )
+
+        messages = [{"role": "system", "content": system_prompt}]
+
+        # Add recent history
+        for query in recent_queries:
+            if "prompt" in query and "response" in query:
+                messages.append({"role": "user", "content": query["prompt"]})
+                messages.append({"role": "assistant", "content": query["response"]})
+
+            # Add tool calls from history if present
+            if include_tool_calls and "tool_calls" in query:
+                for tool_call in query["tool_calls"]:
+                    call_id = tool_call.get("call_id") or str(uuid.uuid4())
+
+                    function_call_dict = {
+                        "function_call": {
+                            "name": tool_call.get("action_name"),
+                            "args": tool_call.get("arguments"),
+                            "call_id": call_id,
+                        }
+                    }
+                    function_response_dict = {
+                        "function_response": {
+                            "name": tool_call.get("action_name"),
+                            "response": {"result": tool_call.get("result")},
+                            "call_id": call_id,
+                        }
+                    }
+
+                    messages.append(
+                        {"role": "assistant", "content": [function_call_dict]}
+                    )
+                    messages.append(
+                        {"role": "tool", "content": [function_response_dict]}
+                    )
+
+        # If no recent queries (everything was compressed), add a continuation user message
+        if len(recent_queries) == 0 and compressed_summary:
+            messages.append({
+                "role": "user",
+                "content": "Please continue with the remaining tasks based on the context above."
+            })
+            logger.info("Added continuation user message to maintain proper turn-taking after full compression")
+
+        return messages
+
+    @staticmethod
+    def _append_compression_context(
+        system_prompt: str, compressed_summary: str, context_type: str = "pre_request"
+    ) -> str:
+        """
+        Append compression context to system prompt.
+
+        Args:
+            system_prompt: Original system prompt
+            compressed_summary: Summary to append
+            context_type: Type of compression context
+
+        Returns:
+            Updated system prompt
+        """
+        # Remove existing compression context if present
+        if "This session is being continued" in system_prompt or "Context window limit reached" in system_prompt:
+            parts = system_prompt.split("\n\n---\n\n")
+            system_prompt = parts[0]
+
+        # Build appropriate context message based on type
+        if context_type == "mid_execution":
+            context_message = (
+                "\n\n---\n\n"
+                "Context window limit reached during execution. "
+                "Previous conversation has been compressed to fit within limits. "
+                "The conversation is summarized below:\n\n"
+                f"{compressed_summary}"
+            )
+        else:  # pre_request
+            context_message = (
+                "\n\n---\n\n"
+                "This session is being continued from a previous conversation that "
+                "has been compressed to fit within context limits. "
+                "The conversation is summarized below:\n\n"
+                f"{compressed_summary}"
+            )
+
+        return system_prompt + context_message
+
+    @staticmethod
+    def rebuild_messages_after_compression(
+        messages: List[Dict],
+        compressed_summary: Optional[str],
+        recent_queries: List[Dict],
+        include_current_execution: bool = False,
+        include_tool_calls: bool = False,
+    ) -> Optional[List[Dict]]:
+        """
+        Rebuild the message list after compression so tool execution can continue.
+
+        Args:
+            messages: Original message list
+            compressed_summary: Compressed summary
+            recent_queries: Recent uncompressed queries
+            include_current_execution: Whether to preserve current execution messages
+            include_tool_calls: Whether to include tool calls from history
+
+        Returns:
+            Rebuilt message list or None if failed
+        """
+        # Find the system message
+        system_message = next(
+            (msg for msg in messages if msg.get("role") == "system"), None
+        )
+        if not system_message:
+            logger.warning("No system message found in messages list")
+            return None
+
+        # Update system message with compressed summary
+        if compressed_summary:
+            content = system_message.get("content", "")
+            system_message["content"] = MessageBuilder._append_compression_context(
+                content, compressed_summary, "mid_execution"
+            )
+            logger.info(
+                "Appended compression summary to system prompt (truncated): %s",
+                (
+                    compressed_summary[:500] + "..."
+                    if len(compressed_summary) > 500
+                    else compressed_summary
+                ),
+            )
+
+        rebuilt_messages = [system_message]
+
+        # Add recent history from compressed context
+        for query in recent_queries:
+            if "prompt" in query and "response" in query:
+                rebuilt_messages.append({"role": "user", "content": query["prompt"]})
+                rebuilt_messages.append(
+                    {"role": "assistant", "content": query["response"]}
+                )
+
+            # Add tool calls from history if present
+            if include_tool_calls and "tool_calls" in query:
+                for tool_call in query["tool_calls"]:
+                    call_id = tool_call.get("call_id") or str(uuid.uuid4())
+
+                    function_call_dict = {
+                        "function_call": {
+                            "name": tool_call.get("action_name"),
+                            "args": tool_call.get("arguments"),
+                            "call_id": call_id,
+                        }
+                    }
+                    function_response_dict = {
+                        "function_response": {
+                            "name": tool_call.get("action_name"),
+                            "response": {"result": tool_call.get("result")},
+                            "call_id": call_id,
+                        }
+                    }
+
+                    rebuilt_messages.append(
+                        {"role": "assistant", "content": [function_call_dict]}
+                    )
+                    rebuilt_messages.append(
+                        {"role": "tool", "content": [function_response_dict]}
+                    )
+
+        # If no recent queries (everything was compressed), add a continuation user message
+        if len(recent_queries) == 0 and compressed_summary:
+            rebuilt_messages.append({
+                "role": "user",
+                "content": "Please continue with the remaining tasks based on the context above."
+            })
+            logger.info("Added continuation user message to maintain proper turn-taking after full compression")
+
+        if include_current_execution:
+            # Preserve any messages that were added during the current execution cycle
+            recent_msg_count = 1  # system message
+            for query in recent_queries:
+                if "prompt" in query and "response" in query:
+                    recent_msg_count += 2
+                if "tool_calls" in query:
+                    recent_msg_count += len(query["tool_calls"]) * 2
+
+            if len(messages) > recent_msg_count:
+                current_execution_messages = messages[recent_msg_count:]
+                rebuilt_messages.extend(current_execution_messages)
+                logger.info(
+                    f"Preserved {len(current_execution_messages)} messages from current execution cycle"
+                )
+
+        logger.info(
+            f"Messages rebuilt: {len(messages)} → {len(rebuilt_messages)} messages. "
+            f"Ready to continue tool execution."
+        )
+        return rebuilt_messages

application/api/answer/services/compression/orchestrator.py

@@ -0,0 +1,232 @@
+"""High-level compression orchestration."""
+
+import logging
+from typing import Any, Dict, Optional
+
+from application.api.answer.services.compression.service import CompressionService
+from application.api.answer.services.compression.threshold_checker import (
+    CompressionThresholdChecker,
+)
+from application.api.answer.services.compression.types import CompressionResult
+from application.api.answer.services.conversation_service import ConversationService
+from application.core.model_utils import (
+    get_api_key_for_provider,
+    get_provider_from_model_id,
+)
+from application.core.settings import settings
+from application.llm.llm_creator import LLMCreator
+
+logger = logging.getLogger(__name__)
+
+
+class CompressionOrchestrator:
+    """
+    Facade for compression operations.
+
+    Coordinates between all compression components and provides
+    a simple interface for callers.
+    """
+
+    def __init__(
+        self,
+        conversation_service: ConversationService,
+        threshold_checker: Optional[CompressionThresholdChecker] = None,
+    ):
+        """
+        Initialize orchestrator.
+
+        Args:
+            conversation_service: Service for DB operations
+            threshold_checker: Custom threshold checker (optional)
+        """
+        self.conversation_service = conversation_service
+        self.threshold_checker = threshold_checker or CompressionThresholdChecker()
+
+    def compress_if_needed(
+        self,
+        conversation_id: str,
+        user_id: str,
+        model_id: str,
+        decoded_token: Dict[str, Any],
+        current_query_tokens: int = 500,
+    ) -> CompressionResult:
+        """
+        Check if compression is needed and perform it if so.
+
+        This is the main entry point for compression operations.
+
+        Args:
+            conversation_id: Conversation ID
+            user_id: User ID
+            model_id: Model being used for conversation
+            decoded_token: User's decoded JWT token
+            current_query_tokens: Estimated tokens for current query
+
+        Returns:
+            CompressionResult with summary and recent queries
+        """
+        try:
+            # Load conversation
+            conversation = self.conversation_service.get_conversation(
+                conversation_id, user_id
+            )
+
+            if not conversation:
+                logger.warning(
+                    f"Conversation {conversation_id} not found for user {user_id}"
+                )
+                return CompressionResult.failure("Conversation not found")
+
+            # Check if compression is needed
+            if not self.threshold_checker.should_compress(
+                conversation, model_id, current_query_tokens
+            ):
+                # No compression needed, return full history
+                queries = conversation.get("queries", [])
+                return CompressionResult.success_no_compression(queries)
+
+            # Perform compression
+            return self._perform_compression(
+                conversation_id, conversation, model_id, decoded_token
+            )
+
+        except Exception as e:
+            logger.error(
+                f"Error in compress_if_needed: {str(e)}", exc_info=True
+            )
+            return CompressionResult.failure(str(e))
+
+    def _perform_compression(
+        self,
+        conversation_id: str,
+        conversation: Dict[str, Any],
+        model_id: str,
+        decoded_token: Dict[str, Any],
+    ) -> CompressionResult:
+        """
+        Perform the actual compression operation.
+
+        Args:
+            conversation_id: Conversation ID
+            conversation: Conversation document
+            model_id: Model ID for conversation
+            decoded_token: User token
+
+        Returns:
+            CompressionResult
+        """
+        try:
+            # Determine which model to use for compression
+            compression_model = (
+                settings.COMPRESSION_MODEL_OVERRIDE
+                if settings.COMPRESSION_MODEL_OVERRIDE
+                else model_id
+            )
+
+            # Get provider and API key for compression model
+            provider = get_provider_from_model_id(compression_model)
+            api_key = get_api_key_for_provider(provider)
+
+            # Create compression LLM
+            compression_llm = LLMCreator.create_llm(
+                provider,
+                api_key=api_key,
+                user_api_key=None,
+                decoded_token=decoded_token,
+                model_id=compression_model,
+            )
+
+            # Create compression service with DB update capability
+            compression_service = CompressionService(
+                llm=compression_llm,
+                model_id=compression_model,
+                conversation_service=self.conversation_service,
+            )
+
+            # Compress all queries up to the latest
+            queries_count = len(conversation.get("queries", []))
+            compress_up_to = queries_count - 1
+
+            if compress_up_to < 0:
+                logger.warning("No queries to compress")
+                return CompressionResult.success_no_compression([])
+
+            logger.info(
+                f"Initiating compression for conversation {conversation_id}: "
+                f"compressing all {queries_count} queries (0-{compress_up_to})"
+            )
+
+            # Perform compression and save to DB
+            metadata = compression_service.compress_and_save(
+                conversation_id, conversation, compress_up_to
+            )
+
+            logger.info(
+                f"Compression successful - ratio: {metadata.compression_ratio:.1f}x, "
+                f"saved {metadata.original_token_count - metadata.compressed_token_count} tokens"
+            )
+
+            # Reload conversation with updated metadata
+            conversation = self.conversation_service.get_conversation(
+                conversation_id, user_id=decoded_token.get("sub")
+            )
+
+            # Get compressed context
+            compressed_summary, recent_queries = (
+                compression_service.get_compressed_context(conversation)
+            )
+
+            return CompressionResult.success_with_compression(
+                compressed_summary, recent_queries, metadata
+            )
+
+        except Exception as e:
+            logger.error(f"Error performing compression: {str(e)}", exc_info=True)
+            return CompressionResult.failure(str(e))
+
+    def compress_mid_execution(
+        self,
+        conversation_id: str,
+        user_id: str,
+        model_id: str,
+        decoded_token: Dict[str, Any],
+        current_conversation: Optional[Dict[str, Any]] = None,
+    ) -> CompressionResult:
+        """
+        Perform compression during tool execution.
+
+        Args:
+            conversation_id: Conversation ID
+            user_id: User ID
+            model_id: Model ID
+            decoded_token: User token
+            current_conversation: Pre-loaded conversation (optional)
+
+        Returns:
+            CompressionResult
+        """
+        try:
+            # Load conversation if not provided
+            if current_conversation:
+                conversation = current_conversation
+            else:
+                conversation = self.conversation_service.get_conversation(
+                    conversation_id, user_id
+                )
+
+            if not conversation:
+                logger.warning(
+                    f"Could not load conversation {conversation_id} for mid-execution compression"
+                )
+                return CompressionResult.failure("Conversation not found")
+
+            # Perform compression
+            return self._perform_compression(
+                conversation_id, conversation, model_id, decoded_token
+            )
+
+        except Exception as e:
+            logger.error(
+                f"Error in mid-execution compression: {str(e)}", exc_info=True
+            )
+            return CompressionResult.failure(str(e))

application/api/answer/services/compression/prompt_builder.py

@@ -0,0 +1,149 @@
+"""Compression prompt building logic."""
+
+import logging
+from pathlib import Path
+from typing import Any, Dict, List, Optional
+
+logger = logging.getLogger(__name__)
+
+
+class CompressionPromptBuilder:
+    """Builds prompts for LLM compression calls."""
+
+    def __init__(self, version: str = "v1.0"):
+        """
+        Initialize prompt builder.
+
+        Args:
+            version: Prompt template version to use
+        """
+        self.version = version
+        self.system_prompt = self._load_prompt(version)
+
+    def _load_prompt(self, version: str) -> str:
+        """
+        Load prompt template from file.
+
+        Args:
+            version: Version string (e.g., 'v1.0')
+
+        Returns:
+            Prompt template content
+
+        Raises:
+            FileNotFoundError: If prompt template file doesn't exist
+        """
+        current_dir = Path(__file__).resolve().parents[4]
+        prompt_path = current_dir / "prompts" / "compression" / f"{version}.txt"
+
+        try:
+            with open(prompt_path, "r") as f:
+                return f.read()
+        except FileNotFoundError:
+            logger.error(f"Compression prompt template not found: {prompt_path}")
+            raise FileNotFoundError(
+                f"Compression prompt template '{version}' not found at {prompt_path}. "
+                f"Please ensure the template file exists."
+            )
+
+    def build_prompt(
+        self,
+        queries: List[Dict[str, Any]],
+        existing_compressions: Optional[List[Dict[str, Any]]] = None,
+    ) -> List[Dict[str, str]]:
+        """
+        Build messages for compression LLM call.
+
+        Args:
+            queries: List of query objects to compress
+            existing_compressions: List of previous compression points
+
+        Returns:
+            List of message dicts for LLM
+        """
+        # Build conversation text
+        conversation_text = self._format_conversation(queries)
+
+        # Add existing compression context if present
+        existing_compression_context = ""
+        if existing_compressions and len(existing_compressions) > 0:
+            existing_compression_context = (
+                "\n\nIMPORTANT: This conversation has been compressed before. "
+                "Previous compression summaries:\n\n"
+            )
+            for i, comp in enumerate(existing_compressions):
+                existing_compression_context += (
+                    f"--- Compression {i + 1} (up to message {comp.get('query_index', 'unknown')}) ---\n"
+                    f"{comp.get('compressed_summary', '')}\n\n"
+                )
+            existing_compression_context += (
+                "Your task is to create a NEW summary that incorporates the context from "
+                "previous compressions AND the new messages below. The final summary should "
+                "be comprehensive and include all important information from both previous "
+                "compressions and new messages.\n\n"
+            )
+
+        user_prompt = (
+            f"{existing_compression_context}"
+            f"Here is the conversation to summarize:\n\n"
+            f"{conversation_text}"
+        )
+
+        messages = [
+            {"role": "system", "content": self.system_prompt},
+            {"role": "user", "content": user_prompt},
+        ]
+
+        return messages
+
+    def _format_conversation(self, queries: List[Dict[str, Any]]) -> str:
+        """
+        Format conversation queries into readable text for compression.
+
+        Args:
+            queries: List of query objects
+
+        Returns:
+            Formatted conversation text
+        """
+        conversation_lines = []
+
+        for i, query in enumerate(queries):
+            conversation_lines.append(f"--- Message {i + 1} ---")
+            conversation_lines.append(f"User: {query.get('prompt', '')}")
+
+            # Add tool calls if present
+            tool_calls = query.get("tool_calls", [])
+            if tool_calls:
+                conversation_lines.append("\nTool Calls:")
+                for tc in tool_calls:
+                    tool_name = tc.get("tool_name", "unknown")
+                    action_name = tc.get("action_name", "unknown")
+                    arguments = tc.get("arguments", {})
+                    result = tc.get("result", "")
+                    if result is None:
+                        result = ""
+                    status = tc.get("status", "unknown")
+
+                    # Include full tool result for complete compression context
+                    conversation_lines.append(
+                        f"  - {tool_name}.{action_name}({arguments}) "
+                        f"[{status}] → {result}"
+                    )
+
+            # Add agent thought if present
+            thought = query.get("thought", "")
+            if thought:
+                conversation_lines.append(f"\nAgent Thought: {thought}")
+
+            # Add assistant response
+            conversation_lines.append(f"\nAssistant: {query.get('response', '')}")
+
+            # Add sources if present
+            sources = query.get("sources", [])
+            if sources:
+                conversation_lines.append(f"\nSources Used: {len(sources)} documents")
+
+            conversation_lines.append("")  # Empty line between messages
+
+        return "\n".join(conversation_lines)

application/api/answer/services/compression/service.py

@@ -0,0 +1,306 @@
+"""Core compression service with simplified responsibilities."""
+
+import logging
+import re
+from datetime import datetime, timezone
+from typing import Any, Dict, List, Optional
+
+from application.api.answer.services.compression.prompt_builder import (
+    CompressionPromptBuilder,
+)
+from application.api.answer.services.compression.token_counter import TokenCounter
+from application.api.answer.services.compression.types import (
+    CompressionMetadata,
+)
+from application.core.settings import settings
+
+logger = logging.getLogger(__name__)
+
+
+class CompressionService:
+    """
+    Service for compressing conversation history.
+
+    Handles DB updates.
+    """
+
+    def __init__(
+        self,
+        llm,
+        model_id: str,
+        conversation_service=None,
+        prompt_builder: Optional[CompressionPromptBuilder] = None,
+    ):
+        """
+        Initialize compression service.
+
+        Args:
+            llm: LLM instance to use for compression
+            model_id: Model ID for compression
+            conversation_service: Service for DB operations (optional, for DB updates)
+            prompt_builder: Custom prompt builder (optional)
+        """
+        self.llm = llm
+        self.model_id = model_id
+        self.conversation_service = conversation_service
+        self.prompt_builder = prompt_builder or CompressionPromptBuilder(
+            version=settings.COMPRESSION_PROMPT_VERSION
+        )
+
+    def compress_conversation(
+        self,
+        conversation: Dict[str, Any],
+        compress_up_to_index: int,
+    ) -> CompressionMetadata:
+        """
+        Compress conversation history up to specified index.
+
+        Args:
+            conversation: Full conversation document
+            compress_up_to_index: Last query index to include in compression
+
+        Returns:
+            CompressionMetadata with compression details
+
+        Raises:
+            ValueError: If compress_up_to_index is invalid
+        """
+        try:
+            queries = conversation.get("queries", [])
+
+            if compress_up_to_index < 0 or compress_up_to_index >= len(queries):
+                raise ValueError(
+                    f"Invalid compress_up_to_index: {compress_up_to_index} "
+                    f"(conversation has {len(queries)} queries)"
+                )
+
+            # Get queries to compress
+            queries_to_compress = queries[: compress_up_to_index + 1]
+
+            # Check if there are existing compressions
+            existing_compressions = conversation.get("compression_metadata", {}).get(
+                "compression_points", []
+            )
+
+            if existing_compressions:
+                logger.info(
+                    f"Found {len(existing_compressions)} previous compression(s) - "
+                    f"will incorporate into new summary"
+                )
+
+            # Calculate original token count
+            original_tokens = TokenCounter.count_query_tokens(queries_to_compress)
+
+            # Log tool call stats
+            self._log_tool_call_stats(queries_to_compress)
+
+            # Build compression prompt
+            messages = self.prompt_builder.build_prompt(
+                queries_to_compress, existing_compressions
+            )
+
+            # Call LLM to generate compression
+            logger.info(
+                f"Starting compression: {len(queries_to_compress)} queries "
+                f"(messages 0-{compress_up_to_index}, {original_tokens} tokens) "
+                f"using model {self.model_id}"
+            )
+
+            response = self.llm.gen(
+                model=self.model_id, messages=messages, max_tokens=4000
+            )
+
+            # Extract summary from response
+            compressed_summary = self._extract_summary(response)
+
+            # Calculate compressed token count
+            compressed_tokens = TokenCounter.count_message_tokens(
+                [{"content": compressed_summary}]
+            )
+
+            # Calculate compression ratio
+            compression_ratio = (
+                original_tokens / compressed_tokens if compressed_tokens > 0 else 0
+            )
+
+            logger.info(
+                f"Compression complete: {original_tokens} → {compressed_tokens} tokens "
+                f"({compression_ratio:.1f}x compression)"
+            )
+
+            # Build compression metadata
+            compression_metadata = CompressionMetadata(
+                timestamp=datetime.now(timezone.utc),
+                query_index=compress_up_to_index,
+                compressed_summary=compressed_summary,
+                original_token_count=original_tokens,
+                compressed_token_count=compressed_tokens,
+                compression_ratio=compression_ratio,
+                model_used=self.model_id,
+                compression_prompt_version=self.prompt_builder.version,
+            )
+
+            return compression_metadata
+
+        except Exception as e:
+            logger.error(f"Error compressing conversation: {str(e)}", exc_info=True)
+            raise
+
+    def compress_and_save(
+        self,
+        conversation_id: str,
+        conversation: Dict[str, Any],
+        compress_up_to_index: int,
+    ) -> CompressionMetadata:
+        """
+        Compress conversation and save to database.
+
+        Args:
+            conversation_id: Conversation ID
+            conversation: Full conversation document
+            compress_up_to_index: Last query index to include
+
+        Returns:
+            CompressionMetadata
+
+        Raises:
+            ValueError: If conversation_service not provided or invalid index
+        """
+        if not self.conversation_service:
+            raise ValueError(
+                "conversation_service required for compress_and_save operation"
+            )
+
+        # Perform compression
+        metadata = self.compress_conversation(conversation, compress_up_to_index)
+
+        # Save to database
+        self.conversation_service.update_compression_metadata(
+            conversation_id, metadata.to_dict()
+        )
+
+        logger.info(f"Compression metadata saved to database for {conversation_id}")
+
+        return metadata
+
+    def get_compressed_context(
+        self, conversation: Dict[str, Any]
+    ) -> tuple[Optional[str], List[Dict[str, Any]]]:
+        """
+        Get compressed summary + recent uncompressed messages.
+
+        Args:
+            conversation: Full conversation document
+
+        Returns:
+            (compressed_summary, recent_messages)
+        """
+        try:
+            compression_metadata = conversation.get("compression_metadata", {})
+
+            if not compression_metadata.get("is_compressed"):
+                logger.debug("No compression metadata found - using full history")
+                queries = conversation.get("queries", [])
+                if queries is None:
+                    logger.error("Conversation queries is None - returning empty list")
+                    return None, []
+                return None, queries
+
+            compression_points = compression_metadata.get("compression_points", [])
+
+            if not compression_points:
+                logger.debug("No compression points found - using full history")
+                queries = conversation.get("queries", [])
+                if queries is None:
+                    logger.error("Conversation queries is None - returning empty list")
+                    return None, []
+                return None, queries
+
+            # Get the most recent compression point
+            latest_compression = compression_points[-1]
+            compressed_summary = latest_compression.get("compressed_summary")
+            last_compressed_index = latest_compression.get("query_index")
+            compressed_tokens = latest_compression.get("compressed_token_count", 0)
+            original_tokens = latest_compression.get("original_token_count", 0)
+
+            # Get only messages after compression point
+            queries = conversation.get("queries", [])
+            total_queries = len(queries)
+            recent_queries = queries[last_compressed_index + 1 :]
+
+            logger.info(
+                f"Using compressed context: summary ({compressed_tokens} tokens, "
+                f"compressed from {original_tokens}) + {len(recent_queries)} recent messages "
+                f"(messages {last_compressed_index + 1}-{total_queries - 1})"
+            )
+
+            return compressed_summary, recent_queries
+
+        except Exception as e:
+            logger.error(
+                f"Error getting compressed context: {str(e)}", exc_info=True
+            )
+            queries = conversation.get("queries", [])
+            if queries is None:
+                return None, []
+            return None, queries
+
+    def _extract_summary(self, llm_response: str) -> str:
+        """
+        Extract clean summary from LLM response.
+
+        Args:
+            llm_response: Raw LLM response
+
+        Returns:
+            Cleaned summary text
+        """
+        try:
+            # Try to extract content within <summary> tags
+            summary_match = re.search(
+                r"<summary>(.*?)</summary>", llm_response, re.DOTALL
+            )
+
+            if summary_match:
+                summary = summary_match.group(1).strip()
+            else:
+                # If no summary tags, remove analysis tags and use the rest
+                summary = re.sub(
+                    r"<analysis>.*?</analysis>", "", llm_response, flags=re.DOTALL
+                ).strip()
+
+            return summary
+
+        except Exception as e:
+            logger.warning(f"Error extracting summary: {str(e)}, using full response")
+            return llm_response
+
+    def _log_tool_call_stats(self, queries: List[Dict[str, Any]]) -> None:
+        """Log statistics about tool calls in queries."""
+        total_tool_calls = 0
+        total_tool_result_chars = 0
+        tool_call_breakdown = {}
+
+        for q in queries:
+            for tc in q.get("tool_calls", []):
+                total_tool_calls += 1
+                tool_name = tc.get("tool_name", "unknown")
+                action_name = tc.get("action_name", "unknown")
+                key = f"{tool_name}.{action_name}"
+                tool_call_breakdown[key] = tool_call_breakdown.get(key, 0) + 1
+
+                # Track total tool result size
+                result = tc.get("result", "")
+                if result:
+                    total_tool_result_chars += len(str(result))
+
+        if total_tool_calls > 0:
+            tool_breakdown_str = ", ".join(
+                f"{tool}({count})"
+                for tool, count in sorted(tool_call_breakdown.items())
+            )
+            tool_result_kb = total_tool_result_chars / 1024
+            logger.info(
+                f"Tool call breakdown: {tool_breakdown_str} "
+                f"(total result size: {tool_result_kb:.1f} KB, {total_tool_result_chars:,} chars)"
+            )

application/api/answer/services/compression/threshold_checker.py

@@ -0,0 +1,103 @@
+"""Compression threshold checking logic."""
+
+import logging
+from typing import Any, Dict
+
+from application.core.model_utils import get_token_limit
+from application.core.settings import settings
+from application.api.answer.services.compression.token_counter import TokenCounter
+
+logger = logging.getLogger(__name__)
+
+
+class CompressionThresholdChecker:
+    """Determines if compression is needed based on token thresholds."""
+
+    def __init__(self, threshold_percentage: float = None):
+        """
+        Initialize threshold checker.
+
+        Args:
+            threshold_percentage: Percentage of context to use as threshold
+                                 (defaults to settings.COMPRESSION_THRESHOLD_PERCENTAGE)
+        """
+        self.threshold_percentage = (
+            threshold_percentage or settings.COMPRESSION_THRESHOLD_PERCENTAGE
+        )
+
+    def should_compress(
+        self,
+        conversation: Dict[str, Any],
+        model_id: str,
+        current_query_tokens: int = 500,
+    ) -> bool:
+        """
+        Determine if compression is needed.
+
+        Args:
+            conversation: Full conversation document
+            model_id: Target model for this request
+            current_query_tokens: Estimated tokens for current query
+
+        Returns:
+            True if tokens >= threshold% of context window
+        """
+        try:
+            # Calculate total tokens in conversation
+            total_tokens = TokenCounter.count_conversation_tokens(conversation)
+            total_tokens += current_query_tokens
+
+            # Get context window limit for model
+            context_limit = get_token_limit(model_id)
+
+            # Calculate threshold
+            threshold = int(context_limit * self.threshold_percentage)
+
+            compression_needed = total_tokens >= threshold
+            percentage_used = (total_tokens / context_limit) * 100
+
+            if compression_needed:
+                logger.warning(
+                    f"COMPRESSION TRIGGERED: {total_tokens} tokens / {context_limit} limit "
+                    f"({percentage_used:.1f}% used, threshold: {self.threshold_percentage * 100:.0f}%)"
+                )
+            else:
+                logger.info(
+                    f"Compression check: {total_tokens}/{context_limit} tokens "
+                    f"({percentage_used:.1f}% used, threshold: {self.threshold_percentage * 100:.0f}%) - No compression needed"
+                )
+
+            return compression_needed
+
+        except Exception as e:
+            logger.error(f"Error checking compression need: {str(e)}", exc_info=True)
+            return False
+
+    def check_message_tokens(self, messages: list, model_id: str) -> bool:
+        """
+        Check if message list exceeds threshold.
+
+        Args:
+            messages: List of message dicts
+            model_id: Target model
+
+        Returns:
+            True if at or above threshold
+        """
+        try:
+            current_tokens = TokenCounter.count_message_tokens(messages)
+            context_limit = get_token_limit(model_id)
+            threshold = int(context_limit * self.threshold_percentage)
+
+            if current_tokens >= threshold:
+                logger.warning(
+                    f"Message context limit approaching: {current_tokens}/{context_limit} tokens "
+                    f"({(current_tokens/context_limit)*100:.1f}%)"
+                )
+                return True
+
+            return False
+
+        except Exception as e:
+            logger.error(f"Error checking message tokens: {str(e)}", exc_info=True)
+            return False

application/api/answer/services/compression/token_counter.py

@@ -0,0 +1,103 @@
+"""Token counting utilities for compression."""
+
+import logging
+from typing import Any, Dict, List
+
+from application.utils import num_tokens_from_string
+from application.core.settings import settings
+
+logger = logging.getLogger(__name__)
+
+
+class TokenCounter:
+    """Centralized token counting for conversations and messages."""
+
+    @staticmethod
+    def count_message_tokens(messages: List[Dict]) -> int:
+        """
+        Calculate total tokens in a list of messages.
+
+        Args:
+            messages: List of message dicts with 'content' field
+
+        Returns:
+            Total token count
+        """
+        total_tokens = 0
+        for message in messages:
+            content = message.get("content", "")
+            if isinstance(content, str):
+                total_tokens += num_tokens_from_string(content)
+            elif isinstance(content, list):
+                # Handle structured content (tool calls, etc.)
+                for item in content:
+                    if isinstance(item, dict):
+                        total_tokens += num_tokens_from_string(str(item))
+        return total_tokens
+
+    @staticmethod
+    def count_query_tokens(
+        queries: List[Dict[str, Any]], include_tool_calls: bool = True
+    ) -> int:
+        """
+        Count tokens across multiple query objects.
+
+        Args:
+            queries: List of query objects from conversation
+            include_tool_calls: Whether to count tool call tokens
+
+        Returns:
+            Total token count
+        """
+        total_tokens = 0
+
+        for query in queries:
+            # Count prompt and response tokens
+            if "prompt" in query:
+                total_tokens += num_tokens_from_string(query["prompt"])
+            if "response" in query:
+                total_tokens += num_tokens_from_string(query["response"])
+            if "thought" in query:
+                total_tokens += num_tokens_from_string(query.get("thought", ""))
+
+            # Count tool call tokens
+            if include_tool_calls and "tool_calls" in query:
+                for tool_call in query["tool_calls"]:
+                    tool_call_string = (
+                        f"Tool: {tool_call.get('tool_name')} | "
+                        f"Action: {tool_call.get('action_name')} | "
+                        f"Args: {tool_call.get('arguments')} | "
+                        f"Response: {tool_call.get('result')}"
+                    )
+                    total_tokens += num_tokens_from_string(tool_call_string)
+
+        return total_tokens
+
+    @staticmethod
+    def count_conversation_tokens(
+        conversation: Dict[str, Any], include_system_prompt: bool = False
+    ) -> int:
+        """
+        Calculate total tokens in a conversation.
+
+        Args:
+            conversation: Conversation document
+            include_system_prompt: Whether to include system prompt in count
+
+        Returns:
+            Total token count
+        """
+        try:
+            queries = conversation.get("queries", [])
+            total_tokens = TokenCounter.count_query_tokens(queries)
+
+            # Add system prompt tokens if requested
+            if include_system_prompt:
+                # Rough estimate for system prompt
+                total_tokens += settings.RESERVED_TOKENS.get("system_prompt", 500)
+
+            return total_tokens
+
+        except Exception as e:
+            logger.error(f"Error calculating conversation tokens: {str(e)}")
+            return 0

application/api/answer/services/compression/types.py

@@ -0,0 +1,83 @@
+"""Type definitions for compression module."""
+
+from dataclasses import dataclass, field
+from datetime import datetime
+from typing import Any, Dict, List, Optional
+
+
+@dataclass
+class CompressionMetadata:
+    """Metadata about a compression operation."""
+
+    timestamp: datetime
+    query_index: int
+    compressed_summary: str
+    original_token_count: int
+    compressed_token_count: int
+    compression_ratio: float
+    model_used: str
+    compression_prompt_version: str
+
+    def to_dict(self) -> Dict[str, Any]:
+        """Convert to dictionary for DB storage."""
+        return {
+            "timestamp": self.timestamp,
+            "query_index": self.query_index,
+            "compressed_summary": self.compressed_summary,
+            "original_token_count": self.original_token_count,
+            "compressed_token_count": self.compressed_token_count,
+            "compression_ratio": self.compression_ratio,
+            "model_used": self.model_used,
+            "compression_prompt_version": self.compression_prompt_version,
+        }
+
+
+@dataclass
+class CompressionResult:
+    """Result of a compression operation."""
+
+    success: bool
+    compressed_summary: Optional[str] = None
+    recent_queries: List[Dict[str, Any]] = field(default_factory=list)
+    metadata: Optional[CompressionMetadata] = None
+    error: Optional[str] = None
+    compression_performed: bool = False
+
+    @classmethod
+    def success_with_compression(
+        cls, summary: str, queries: List[Dict], metadata: CompressionMetadata
+    ) -> "CompressionResult":
+        """Create a successful result with compression."""
+        return cls(
+            success=True,
+            compressed_summary=summary,
+            recent_queries=queries,
+            metadata=metadata,
+            compression_performed=True,
+        )
+
+    @classmethod
+    def success_no_compression(cls, queries: List[Dict]) -> "CompressionResult":
+        """Create a successful result without compression needed."""
+        return cls(
+            success=True,
+            recent_queries=queries,
+            compression_performed=False,
+        )
+
+    @classmethod
+    def failure(cls, error: str) -> "CompressionResult":
+        """Create a failure result."""
+        return cls(success=False, error=error, compression_performed=False)
+
+    def as_history(self) -> List[Dict[str, str]]:
+        """
+        Convert recent queries to history format.
+
+        Returns:
+            List of prompt/response dicts
+        """
+        return [
+            {"prompt": q["prompt"], "response": q["response"]}
+            for q in self.recent_queries
+        ]

application/api/answer/services/conversation_service.py

@@ -180,3 +180,103 @@ class ConversationService:
                     conversation_data["api_key"] = agent["key"]
             result = self.conversations_collection.insert_one(conversation_data)
             return str(result.inserted_id)
+
+    def update_compression_metadata(
+        self, conversation_id: str, compression_metadata: Dict[str, Any]
+    ) -> None:
+        """
+        Update conversation with compression metadata.
+
+        Uses $push with $slice to keep only the most recent compression points,
+        preventing unbounded array growth. Since each compression incorporates
+        previous compressions, older points become redundant.
+
+        Args:
+            conversation_id: Conversation ID
+            compression_metadata: Compression point data
+        """
+        try:
+            self.conversations_collection.update_one(
+                {"_id": ObjectId(conversation_id)},
+                {
+                    "$set": {
+                        "compression_metadata.is_compressed": True,
+                        "compression_metadata.last_compression_at": compression_metadata.get(
+                            "timestamp"
+                        ),
+                    },
+                    "$push": {
+                        "compression_metadata.compression_points": {
+                            "$each": [compression_metadata],
+                            "$slice": -settings.COMPRESSION_MAX_HISTORY_POINTS,
+                        }
+                    },
+                },
+            )
+            logger.info(
+                f"Updated compression metadata for conversation {conversation_id}"
+            )
+        except Exception as e:
+            logger.error(
+                f"Error updating compression metadata: {str(e)}", exc_info=True
+            )
+            raise
+
+    def append_compression_message(
+        self, conversation_id: str, compression_metadata: Dict[str, Any]
+    ) -> None:
+        """
+        Append a synthetic compression summary entry into the conversation history.
+        This makes the summary visible in the DB alongside normal queries.
+        """
+        try:
+            summary = compression_metadata.get("compressed_summary", "")
+            if not summary:
+                return
+            timestamp = compression_metadata.get("timestamp", datetime.now(timezone.utc))
+
+            self.conversations_collection.update_one(
+                {"_id": ObjectId(conversation_id)},
+                {
+                    "$push": {
+                        "queries": {
+                            "prompt": "[Context Compression Summary]",
+                            "response": summary,
+                            "thought": "",
+                            "sources": [],
+                            "tool_calls": [],
+                            "timestamp": timestamp,
+                            "attachments": [],
+                            "model_id": compression_metadata.get("model_used"),
+                        }
+                    }
+                },
+            )
+            logger.info(f"Appended compression summary to conversation {conversation_id}")
+        except Exception as e:
+            logger.error(
+                f"Error appending compression summary: {str(e)}", exc_info=True
+            )
+
+    def get_compression_metadata(
+        self, conversation_id: str
+    ) -> Optional[Dict[str, Any]]:
+        """
+        Get compression metadata for a conversation.
+
+        Args:
+            conversation_id: Conversation ID
+
+        Returns:
+            Compression metadata dict or None
+        """
+        try:
+            conversation = self.conversations_collection.find_one(
+                {"_id": ObjectId(conversation_id)}, {"compression_metadata": 1}
+            )
+            return conversation.get("compression_metadata") if conversation else None
+        except Exception as e:
+            logger.error(
+                f"Error getting compression metadata: {str(e)}", exc_info=True
+            )
+            return None

application/api/answer/services/stream_processor.py

@@ -10,6 +10,8 @@ from bson.dbref import DBRef
 from bson.objectid import ObjectId
 
 from application.agents.agent_creator import AgentCreator
+from application.api.answer.services.compression import CompressionOrchestrator
+from application.api.answer.services.compression.token_counter import TokenCounter
 from application.api.answer.services.conversation_service import ConversationService
 from application.api.answer.services.prompt_renderer import PromptRenderer
 from application.core.model_utils import (
@@ -90,9 +92,14 @@ class StreamProcessor:
         self.shared_token = None
         self.model_id: Optional[str] = None
         self.conversation_service = ConversationService()
+        self.compression_orchestrator = CompressionOrchestrator(
+            self.conversation_service
+        )
         self.prompt_renderer = PromptRenderer()
         self._prompt_content: Optional[str] = None
         self._required_tool_actions: Optional[Dict[str, Set[Optional[str]]]] = None
+        self.compressed_summary: Optional[str] = None
+        self.compressed_summary_tokens: int = 0
 
     def initialize(self):
         """Initialize all required components for processing"""
@@ -112,15 +119,72 @@ class StreamProcessor:
             )
             if not conversation:
                 raise ValueError("Conversation not found or unauthorized")
-            self.history = [
-                {"prompt": query["prompt"], "response": query["response"]}
-                for query in conversation.get("queries", [])
-            ]
+
+            # Check if compression is enabled and needed
+            if settings.ENABLE_CONVERSATION_COMPRESSION:
+                self._handle_compression(conversation)
+            else:
+                # Original behavior - load all history
+                self.history = [
+                    {"prompt": query["prompt"], "response": query["response"]}
+                    for query in conversation.get("queries", [])
+                ]
         else:
             self.history = limit_chat_history(
                 json.loads(self.data.get("history", "[]")), model_id=self.model_id
             )
 
+    def _handle_compression(self, conversation: Dict[str, Any]):
+        """
+        Handle conversation compression logic using orchestrator.
+
+        Args:
+            conversation: Full conversation document
+        """
+        try:
+            # Use orchestrator to handle all compression logic
+            result = self.compression_orchestrator.compress_if_needed(
+                conversation_id=self.conversation_id,
+                user_id=self.initial_user_id,
+                model_id=self.model_id,
+                decoded_token=self.decoded_token,
+            )
+
+            if not result.success:
+                logger.error(
+                    f"Compression failed: {result.error}, using full history"
+                )
+                self.history = [
+                    {"prompt": query["prompt"], "response": query["response"]}
+                    for query in conversation.get("queries", [])
+                ]
+                return
+
+            # Set compressed summary if compression was performed
+            if result.compression_performed and result.compressed_summary:
+                self.compressed_summary = result.compressed_summary
+                self.compressed_summary_tokens = TokenCounter.count_message_tokens(
+                    [{"content": result.compressed_summary}]
+                )
+                logger.info(
+                    f"Using compressed summary ({self.compressed_summary_tokens} tokens) "
+                    f"+ {len(result.recent_queries)} recent messages"
+                )
+
+            # Build history from recent queries
+            self.history = result.as_history()
+
+        except Exception as e:
+            logger.error(
+                f"Error handling compression, falling back to standard history: {str(e)}",
+                exc_info=True,
+            )
+            # Fallback to original behavior
+            self.history = [
+                {"prompt": query["prompt"], "response": query["response"]}
+                for query in conversation.get("queries", [])
+            ]
+
     def _process_attachments(self):
         """Process any attachments in the request"""
         attachment_ids = self.data.get("attachments", [])
@@ -658,7 +722,7 @@ class StreamProcessor:
         )
         system_api_key = get_api_key_for_provider(provider or settings.LLM_PROVIDER)
 
-        return AgentCreator.create_agent(
+        agent = AgentCreator.create_agent(
             self.agent_config["agent_type"],
             endpoint="stream",
             llm_name=provider or settings.LLM_PROVIDER,
@@ -671,4 +735,10 @@ class StreamProcessor:
             decoded_token=self.decoded_token,
             attachments=self.attachments,
             json_schema=self.agent_config.get("json_schema"),
+            compressed_summary=self.compressed_summary,
         )
+
+        agent.conversation_id = self.conversation_id
+        agent.initial_user_id = self.initial_user_id
+
+        return agent

application/core/model_configs.py

@@ -29,63 +29,29 @@ GOOGLE_ATTACHMENTS = [
 
 OPENAI_MODELS = [
     AvailableModel(
-        id="gpt-4o",
+        id="gpt-5.1",
         provider=ModelProvider.OPENAI,
-        display_name="GPT-4 Omni",
-        description="Latest and most capable model",
+        display_name="GPT-5.1",
+        description="Flagship model with enhanced reasoning, coding, and agentic capabilities",
         capabilities=ModelCapabilities(
             supports_tools=True,
             supports_structured_output=True,
             supported_attachment_types=OPENAI_ATTACHMENTS,
-            context_window=128000,
+            context_window=400000,
         ),
     ),
     AvailableModel(
-        id="gpt-4o-mini",
+        id="gpt-5-mini",
         provider=ModelProvider.OPENAI,
-        display_name="GPT-4 Omni Mini",
-        description="Fast and efficient",
+        display_name="GPT-5 Mini",
+        description="Faster, cost-effective variant of GPT-5.1",
         capabilities=ModelCapabilities(
             supports_tools=True,
             supports_structured_output=True,
             supported_attachment_types=OPENAI_ATTACHMENTS,
-            context_window=128000,
+            context_window=400000,
         ),
-    ),
-    AvailableModel(
-        id="gpt-4-turbo",
-        provider=ModelProvider.OPENAI,
-        display_name="GPT-4 Turbo",
-        description="Fast GPT-4 with 128k context",
-        capabilities=ModelCapabilities(
-            supports_tools=True,
-            supports_structured_output=True,
-            supported_attachment_types=OPENAI_ATTACHMENTS,
-            context_window=128000,
-        ),
-    ),
-    AvailableModel(
-        id="gpt-4",
-        provider=ModelProvider.OPENAI,
-        display_name="GPT-4",
-        description="Most capable model",
-        capabilities=ModelCapabilities(
-            supports_tools=True,
-            supports_structured_output=True,
-            supported_attachment_types=OPENAI_ATTACHMENTS,
-            context_window=8192,
-        ),
-    ),
-    AvailableModel(
-        id="gpt-3.5-turbo",
-        provider=ModelProvider.OPENAI,
-        display_name="GPT-3.5 Turbo",
-        description="Fast and cost-effective",
-        capabilities=ModelCapabilities(
-            supports_tools=True,
-            context_window=4096,
-        ),
-    ),
+    )
 ]
 
 
@@ -159,15 +125,15 @@ GOOGLE_MODELS = [
         ),
     ),
     AvailableModel(
-        id="gemini-2.5-pro",
+        id="gemini-3-pro-preview",
         provider=ModelProvider.GOOGLE,
-        display_name="Gemini 2.5 Pro",
+        display_name="Gemini 3 Pro",
         description="Most capable Gemini model",
         capabilities=ModelCapabilities(
             supports_tools=True,
             supports_structured_output=True,
             supported_attachment_types=GOOGLE_ATTACHMENTS,
-            context_window=2000000,
+            context_window=20000,  # Set low for testing compression
         ),
     ),
 ]

application/core/settings.py

@@ -144,6 +144,13 @@ class Settings(BaseSettings):
     # Tool pre-fetch settings
     ENABLE_TOOL_PREFETCH: bool = True
 
+    # Conversation Compression Settings
+    ENABLE_CONVERSATION_COMPRESSION: bool = True
+    COMPRESSION_THRESHOLD_PERCENTAGE: float = 0.8  # Trigger at 80% of context
+    COMPRESSION_MODEL_OVERRIDE: Optional[str] = None  # Use different model for compression
+    COMPRESSION_PROMPT_VERSION: str = "v1.0"  # Track prompt iterations
+    COMPRESSION_MAX_HISTORY_POINTS: int = 3  # Keep only last N compression points to prevent DB bloat
+
 
 path = Path(__file__).parent.parent.absolute()
 settings = Settings(_env_file=path.joinpath(".env"), _env_file_encoding="utf-8")

application/llm/google_ai.py

@@ -1,4 +1,3 @@
-import json
 import logging
 
 from google import genai
@@ -11,11 +10,13 @@ from application.storage.storage_creator import StorageCreator
 
 
 class GoogleLLM(BaseLLM):
-    def __init__(self, api_key=None, user_api_key=None, *args, **kwargs):
+    def __init__(
+        self, api_key=None, user_api_key=None, decoded_token=None, *args, **kwargs
+    ):
         super().__init__(*args, **kwargs)
         self.api_key = api_key or settings.GOOGLE_API_KEY or settings.API_KEY
         self.user_api_key = user_api_key
-        
+
         self.client = genai.Client(api_key=self.api_key)
         self.storage = StorageCreator.get_storage()
 
@@ -33,6 +34,12 @@ class GoogleLLM(BaseLLM):
             "image/jpg",
             "image/webp",
             "image/gif",
+            "application/pdf",
+            "image/png",
+            "image/jpeg",
+            "image/jpg",
+            "image/webp",
+            "image/gif",
         ]
 
     def prepare_messages_with_attachments(self, messages, attachments=None):
@@ -135,12 +142,38 @@ class GoogleLLM(BaseLLM):
             raise
 
     def _clean_messages_google(self, messages):
-        """Convert OpenAI format messages to Google AI format."""
+        """
+        Convert OpenAI format messages to Google AI format and collect system prompts.
+
+        Returns:
+            tuple[list[types.Content], Optional[str]]: cleaned messages and optional
+            combined system instruction.
+        """
         cleaned_messages = []
+        system_instructions = []
+
+        def _extract_system_text(content):
+            if isinstance(content, str):
+                return content
+            if isinstance(content, list):
+                parts = []
+                for item in content:
+                    if isinstance(item, dict) and "text" in item and item["text"] is not None:
+                        parts.append(item["text"])
+                return "\n".join(parts)
+            return ""
+
         for message in messages:
             role = message.get("role")
             content = message.get("content")
 
+            # Gemini only accepts user/model in the contents list.
+            if role == "system":
+                sys_text = _extract_system_text(content)
+                if sys_text:
+                    system_instructions.append(sys_text)
+                continue
+
             if role == "assistant":
                 role = "model"
             elif role == "tool":
@@ -159,12 +192,27 @@ class GoogleLLM(BaseLLM):
                             cleaned_args = self._remove_null_values(
                                 item["function_call"]["args"]
                             )
-                            parts.append(
-                                types.Part.from_function_call(
-                                    name=item["function_call"]["name"],
-                                    args=cleaned_args,
+                            # Create function call part with thought_signature if present
+                            # For Gemini 3 models, we need to include thought_signature
+                            if "thought_signature" in item:
+                                # Use Part constructor with functionCall and thoughtSignature
+                                parts.append(
+                                    types.Part(
+                                        functionCall=types.FunctionCall(
+                                            name=item["function_call"]["name"],
+                                            args=cleaned_args,
+                                        ),
+                                        thoughtSignature=item["thought_signature"],
+                                    )
+                                )
+                            else:
+                                # Use helper method when no thought_signature
+                                parts.append(
+                                    types.Part.from_function_call(
+                                        name=item["function_call"]["name"],
+                                        args=cleaned_args,
+                                    )
                                 )
-                            )
                         elif "function_response" in item:
                             parts.append(
                                 types.Part.from_function_response(
@@ -188,7 +236,8 @@ class GoogleLLM(BaseLLM):
                     raise ValueError(f"Unexpected content type: {type(content)}")
                 if parts:
                     cleaned_messages.append(types.Content(role=role, parts=parts))
-        return cleaned_messages
+        system_instruction = "\n\n".join(system_instructions) if system_instructions else None
+        return cleaned_messages, system_instruction
 
     def _clean_schema(self, schema_obj):
         """
@@ -274,6 +323,61 @@ class GoogleLLM(BaseLLM):
                 genai_tools.append(genai_tool)
         return genai_tools
 
+    def _extract_preview_from_message(self, message):
+        """Get a short, human-readable preview from the last message."""
+        try:
+            if hasattr(message, "parts"):
+                for part in reversed(message.parts):
+                    if getattr(part, "text", None):
+                        return part.text
+                    function_call = getattr(part, "function_call", None)
+                    if function_call:
+                        name = getattr(function_call, "name", "") or "function_call"
+                        return f"function_call:{name}"
+                    function_response = getattr(part, "function_response", None)
+                    if function_response:
+                        name = getattr(function_response, "name", "") or "function_response"
+                        return f"function_response:{name}"
+            if isinstance(message, dict):
+                content = message.get("content")
+                if isinstance(content, str):
+                    return content
+                if isinstance(content, list):
+                    for item in reversed(content):
+                        if isinstance(item, str):
+                            return item
+                        if isinstance(item, dict):
+                            if item.get("text"):
+                                return item["text"]
+                            if item.get("function_call"):
+                                fn = item["function_call"]
+                                if isinstance(fn, dict):
+                                    name = fn.get("name") or "function_call"
+                                    return f"function_call:{name}"
+                                return "function_call"
+                            if item.get("function_response"):
+                                resp = item["function_response"]
+                                if isinstance(resp, dict):
+                                    name = resp.get("name") or "function_response"
+                                    return f"function_response:{name}"
+                                return "function_response"
+                if "text" in message and isinstance(message["text"], str):
+                    return message["text"]
+        except Exception:
+            pass
+        return str(message)
+
+    def _summarize_messages_for_log(self, messages, preview_chars=20):
+        """Return a compact summary for logging to avoid huge payloads."""
+        message_count = len(messages) if messages else 0
+        last_preview = ""
+        if messages:
+            last_preview = self._extract_preview_from_message(messages[-1]) or ""
+        last_preview = str(last_preview).replace("\n", " ")
+        if len(last_preview) > preview_chars:
+            last_preview = f"{last_preview[:preview_chars]}..."
+        return f"count={message_count}, last='{last_preview}'"
+
     def _raw_gen(
         self,
         baseself,
@@ -287,12 +391,12 @@ class GoogleLLM(BaseLLM):
     ):
         """Generate content using Google AI API without streaming."""
         client = genai.Client(api_key=self.api_key)
+        system_instruction = None
         if formatting == "openai":
-            messages = self._clean_messages_google(messages)
+            messages, system_instruction = self._clean_messages_google(messages)
         config = types.GenerateContentConfig()
-        if messages[0].role == "system":
-            config.system_instruction = messages[0].parts[0].text
-            messages = messages[1:]
+        if system_instruction:
+            config.system_instruction = system_instruction
         if tools:
             cleaned_tools = self._clean_tools_format(tools)
             config.tools = cleaned_tools
@@ -325,12 +429,12 @@ class GoogleLLM(BaseLLM):
     ):
         """Generate content using Google AI API with streaming."""
         client = genai.Client(api_key=self.api_key)
+        system_instruction = None
         if formatting == "openai":
-            messages = self._clean_messages_google(messages)
+            messages, system_instruction = self._clean_messages_google(messages)
         config = types.GenerateContentConfig()
-        if messages[0].role == "system":
-            config.system_instruction = messages[0].parts[0].text
-            messages = messages[1:]
+        if system_instruction:
+            config.system_instruction = system_instruction
         if tools:
             cleaned_tools = self._clean_tools_format(tools)
             config.tools = cleaned_tools
@@ -349,8 +453,12 @@ class GoogleLLM(BaseLLM):
                     break
             if has_attachments:
                 break
+        messages_summary = self._summarize_messages_for_log(messages)
         logging.info(
-            f"GoogleLLM: Starting stream generation. Model: {model}, Messages: {json.dumps(messages, default=str)}, Has attachments: {has_attachments}"
+            "GoogleLLM: Starting stream generation. Model: %s, Messages: %s, Has attachments: %s",
+            model,
+            messages_summary,
+            has_attachments,
         )
 
         response = client.models.generate_content_stream(

application/llm/handlers/base.py

@@ -1,4 +1,5 @@
 import logging
+import uuid
 from abc import ABC, abstractmethod
 from dataclasses import dataclass
 from typing import Any, Dict, Generator, List, Optional, Union
@@ -16,6 +17,7 @@ class ToolCall:
     name: str
     arguments: Union[str, Dict]
     index: Optional[int] = None
+    thought_signature: Optional[str] = None
 
     @classmethod
     def from_dict(cls, data: Dict) -> "ToolCall":
@@ -178,6 +180,406 @@ class LLMHandler(ABC):
             system_msg["content"] += f"\n\n{combined_text}"
         return prepared_messages
 
+    def _prune_messages_minimal(self, messages: List[Dict]) -> Optional[List[Dict]]:
+        """
+        Build a minimal context: system prompt + latest user message only.
+        Drops all tool/function messages to shrink context aggressively.
+        """
+        system_message = next((m for m in messages if m.get("role") == "system"), None)
+        if not system_message:
+            logger.warning("Cannot prune messages minimally: missing system message.")
+            return None
+        last_non_system = None
+        for m in reversed(messages):
+            if m.get("role") == "user":
+                last_non_system = m
+                break
+            if not last_non_system and m.get("role") not in ("system", None):
+                last_non_system = m
+        if not last_non_system:
+            logger.warning("Cannot prune messages minimally: missing user/assistant messages.")
+            return None
+        logger.info("Pruning context to system + latest user/assistant message to proceed.")
+        return [system_message, last_non_system]
+
+    def _extract_text_from_content(self, content: Any) -> str:
+        """
+        Convert message content (str or list of parts) to plain text for compression.
+        """
+        if isinstance(content, str):
+            return content
+        if isinstance(content, list):
+            parts_text = []
+            for item in content:
+                if isinstance(item, dict):
+                    if "text" in item and item["text"] is not None:
+                        parts_text.append(str(item["text"]))
+                    elif "function_call" in item or "function_response" in item:
+                        # Keep serialized function calls/responses so the compressor sees actions
+                        parts_text.append(str(item))
+                    elif "files" in item:
+                        parts_text.append(str(item))
+            return "\n".join(parts_text)
+        return ""
+
+    def _build_conversation_from_messages(self, messages: List[Dict]) -> Optional[Dict]:
+        """
+        Build a conversation-like dict from current messages so we can compress
+        even when the conversation isn't persisted yet. Includes tool calls/results.
+        """
+        queries = []
+        current_prompt = None
+        current_tool_calls = {}
+
+        def _commit_query(response_text: str):
+            nonlocal current_prompt, current_tool_calls
+            if current_prompt is None and not response_text:
+                return
+            tool_calls_list = list(current_tool_calls.values())
+            queries.append(
+                {
+                    "prompt": current_prompt or "",
+                    "response": response_text,
+                    "tool_calls": tool_calls_list,
+                }
+            )
+            current_prompt = None
+            current_tool_calls = {}
+
+        for message in messages:
+            role = message.get("role")
+            content = message.get("content")
+
+            if role == "user":
+                current_prompt = self._extract_text_from_content(content)
+
+            elif role in {"assistant", "model"}:
+                # If this assistant turn contains tool calls, collect them; otherwise commit a response.
+                if isinstance(content, list):
+                    for item in content:
+                        if "function_call" in item:
+                            fc = item["function_call"]
+                            call_id = fc.get("call_id") or str(uuid.uuid4())
+                            current_tool_calls[call_id] = {
+                                "tool_name": "unknown_tool",
+                                "action_name": fc.get("name"),
+                                "arguments": fc.get("args"),
+                                "result": None,
+                                "status": "called",
+                                "call_id": call_id,
+                            }
+                        elif "function_response" in item:
+                            fr = item["function_response"]
+                            call_id = fr.get("call_id") or str(uuid.uuid4())
+                            current_tool_calls[call_id] = {
+                                "tool_name": "unknown_tool",
+                                "action_name": fr.get("name"),
+                                "arguments": None,
+                                "result": fr.get("response", {}).get("result"),
+                                "status": "completed",
+                                "call_id": call_id,
+                            }
+                    # No direct assistant text here; continue to next message
+                    continue
+
+                response_text = self._extract_text_from_content(content)
+                _commit_query(response_text)
+
+            elif role == "tool":
+                # Attach tool outputs to the latest pending tool call if possible
+                tool_text = self._extract_text_from_content(content)
+                # Attempt to parse function_response style
+                call_id = None
+                if isinstance(content, list):
+                    for item in content:
+                        if "function_response" in item and item["function_response"].get("call_id"):
+                            call_id = item["function_response"]["call_id"]
+                            break
+                if call_id and call_id in current_tool_calls:
+                    current_tool_calls[call_id]["result"] = tool_text
+                    current_tool_calls[call_id]["status"] = "completed"
+                elif queries:
+                    queries[-1].setdefault("tool_calls", []).append(
+                        {
+                            "tool_name": "unknown_tool",
+                            "action_name": "unknown_action",
+                            "arguments": {},
+                            "result": tool_text,
+                            "status": "completed",
+                        }
+                    )
+
+        # If there's an unfinished prompt with tool_calls but no response yet, commit it
+        if current_prompt is not None or current_tool_calls:
+            _commit_query(response_text="")
+
+        if not queries:
+            return None
+
+        return {
+            "queries": queries,
+            "compression_metadata": {
+                "is_compressed": False,
+                "compression_points": [],
+            },
+        }
+
+    def _rebuild_messages_after_compression(
+        self,
+        messages: List[Dict],
+        compressed_summary: Optional[str],
+        recent_queries: List[Dict],
+        include_current_execution: bool = False,
+        include_tool_calls: bool = False,
+    ) -> Optional[List[Dict]]:
+        """
+        Rebuild the message list after compression so tool execution can continue.
+
+        Delegates to MessageBuilder for the actual reconstruction.
+        """
+        from application.api.answer.services.compression.message_builder import (
+            MessageBuilder,
+        )
+
+        return MessageBuilder.rebuild_messages_after_compression(
+            messages=messages,
+            compressed_summary=compressed_summary,
+            recent_queries=recent_queries,
+            include_current_execution=include_current_execution,
+            include_tool_calls=include_tool_calls,
+        )
+
+    def _perform_mid_execution_compression(
+        self, agent, messages: List[Dict]
+    ) -> tuple[bool, Optional[List[Dict]]]:
+        """
+        Perform compression during tool execution and rebuild messages.
+
+        Uses the new orchestrator for simplified compression.
+
+        Args:
+            agent: The agent instance
+            messages: Current conversation messages
+
+        Returns:
+            (success: bool, rebuilt_messages: Optional[List[Dict]])
+        """
+        try:
+            from application.api.answer.services.compression import (
+                CompressionOrchestrator,
+            )
+            from application.api.answer.services.conversation_service import (
+                ConversationService,
+            )
+
+            conversation_service = ConversationService()
+            orchestrator = CompressionOrchestrator(conversation_service)
+
+            # Get conversation from database (may be None for new sessions)
+            conversation = conversation_service.get_conversation(
+                agent.conversation_id, agent.initial_user_id
+            )
+
+            if conversation:
+                # Merge current in-flight messages (including tool calls)
+                conversation_from_msgs = self._build_conversation_from_messages(messages)
+                if conversation_from_msgs:
+                    conversation = conversation_from_msgs
+            else:
+                logger.warning(
+                    "Could not load conversation for compression; attempting in-memory compression"
+                )
+                return self._perform_in_memory_compression(agent, messages)
+
+            # Use orchestrator to perform compression
+            result = orchestrator.compress_mid_execution(
+                conversation_id=agent.conversation_id,
+                user_id=agent.initial_user_id,
+                model_id=agent.model_id,
+                decoded_token=getattr(agent, "decoded_token", {}),
+                current_conversation=conversation,
+            )
+
+            if not result.success:
+                logger.warning(f"Mid-execution compression failed: {result.error}")
+                # Try minimal pruning as fallback
+                pruned = self._prune_messages_minimal(messages)
+                if pruned:
+                    agent.context_limit_reached = False
+                    agent.current_token_count = 0
+                    return True, pruned
+                return False, None
+
+            if not result.compression_performed:
+                logger.warning("Compression not performed")
+                return False, None
+
+            # Check if compression actually reduced tokens
+            if result.metadata:
+                if result.metadata.compressed_token_count >= result.metadata.original_token_count:
+                    logger.warning(
+                        "Compression did not reduce token count; falling back to minimal pruning"
+                    )
+                    pruned = self._prune_messages_minimal(messages)
+                    if pruned:
+                        agent.context_limit_reached = False
+                        agent.current_token_count = 0
+                        return True, pruned
+                    return False, None
+
+                logger.info(
+                    f"Mid-execution compression successful - ratio: {result.metadata.compression_ratio:.1f}x, "
+                    f"saved {result.metadata.original_token_count - result.metadata.compressed_token_count} tokens"
+                )
+
+            # Also store the compression summary as a visible message
+            if result.metadata:
+                conversation_service.append_compression_message(
+                    agent.conversation_id, result.metadata.to_dict()
+                )
+
+            # Update agent's compressed summary for downstream persistence
+            agent.compressed_summary = result.compressed_summary
+            agent.compression_metadata = result.metadata.to_dict() if result.metadata else None
+            agent.compression_saved = False
+
+            # Reset the context limit flag so tools can continue
+            agent.context_limit_reached = False
+            agent.current_token_count = 0
+
+            # Rebuild messages
+            rebuilt_messages = self._rebuild_messages_after_compression(
+                messages,
+                result.compressed_summary,
+                result.recent_queries,
+                include_current_execution=False,
+                include_tool_calls=False,
+            )
+
+            if rebuilt_messages is None:
+                return False, None
+
+            return True, rebuilt_messages
+
+        except Exception as e:
+            logger.error(
+                f"Error performing mid-execution compression: {str(e)}", exc_info=True
+            )
+            return False, None
+
+    def _perform_in_memory_compression(
+        self, agent, messages: List[Dict]
+    ) -> tuple[bool, Optional[List[Dict]]]:
+        """
+        Fallback compression path when the conversation is not yet persisted.
+
+        Uses CompressionService directly without DB persistence.
+        """
+        try:
+            from application.api.answer.services.compression.service import (
+                CompressionService,
+            )
+            from application.core.model_utils import (
+                get_api_key_for_provider,
+                get_provider_from_model_id,
+            )
+            from application.core.settings import settings
+            from application.llm.llm_creator import LLMCreator
+
+            conversation = self._build_conversation_from_messages(messages)
+            if not conversation:
+                logger.warning(
+                    "Cannot perform in-memory compression: no user/assistant turns found"
+                )
+                return False, None
+
+            compression_model = (
+                settings.COMPRESSION_MODEL_OVERRIDE
+                if settings.COMPRESSION_MODEL_OVERRIDE
+                else agent.model_id
+            )
+            provider = get_provider_from_model_id(compression_model)
+            api_key = get_api_key_for_provider(provider)
+            compression_llm = LLMCreator.create_llm(
+                provider,
+                api_key,
+                getattr(agent, "user_api_key", None),
+                getattr(agent, "decoded_token", None),
+                model_id=compression_model,
+            )
+
+            # Create service without DB persistence capability
+            compression_service = CompressionService(
+                llm=compression_llm,
+                model_id=compression_model,
+                conversation_service=None,  # No DB updates for in-memory
+            )
+
+            queries_count = len(conversation.get("queries", []))
+            compress_up_to = queries_count - 1
+
+            if compress_up_to < 0 or queries_count == 0:
+                logger.warning("Not enough queries to compress in-memory context")
+                return False, None
+
+            metadata = compression_service.compress_conversation(
+                conversation,
+                compress_up_to_index=compress_up_to,
+            )
+
+            # If compression doesn't reduce tokens, fall back to minimal pruning
+            if (
+                metadata.compressed_token_count
+                >= metadata.original_token_count
+            ):
+                logger.warning(
+                    "In-memory compression did not reduce token count; falling back to minimal pruning"
+                )
+                pruned = self._prune_messages_minimal(messages)
+                if pruned:
+                    agent.context_limit_reached = False
+                    agent.current_token_count = 0
+                    return True, pruned
+                return False, None
+
+            # Attach metadata to synthetic conversation
+            conversation["compression_metadata"] = {
+                "is_compressed": True,
+                "compression_points": [metadata.to_dict()],
+            }
+
+            compressed_summary, recent_queries = (
+                compression_service.get_compressed_context(conversation)
+            )
+
+            agent.compressed_summary = compressed_summary
+            agent.compression_metadata = metadata.to_dict()
+            agent.compression_saved = False
+            agent.context_limit_reached = False
+            agent.current_token_count = 0
+
+            rebuilt_messages = self._rebuild_messages_after_compression(
+                messages,
+                compressed_summary,
+                recent_queries,
+                include_current_execution=False,
+                include_tool_calls=False,
+            )
+            if rebuilt_messages is None:
+                return False, None
+
+            logger.info(
+                f"In-memory compression successful - ratio: {metadata.compression_ratio:.1f}x, "
+                f"saved {metadata.original_token_count - metadata.compressed_token_count} tokens"
+            )
+            return True, rebuilt_messages
+
+        except Exception as e:
+            logger.error(
+                f"Error performing in-memory compression: {str(e)}", exc_info=True
+            )
+            return False, None
+
     def handle_tool_calls(
         self, agent, tool_calls: List[ToolCall], tools_dict: Dict, messages: List[Dict]
     ) -> Generator:
@@ -195,7 +597,110 @@ class LLMHandler(ABC):
         """
         updated_messages = messages.copy()
 
-        for call in tool_calls:
+        for i, call in enumerate(tool_calls):
+            # Check context limit before executing tool call
+            if hasattr(agent, '_check_context_limit') and agent._check_context_limit(updated_messages):
+                # Context limit reached - attempt mid-execution compression
+                compression_attempted = False
+                compression_successful = False
+
+                try:
+                    from application.core.settings import settings
+                    compression_enabled = settings.ENABLE_CONVERSATION_COMPRESSION
+                except Exception:
+                    compression_enabled = False
+
+                if compression_enabled:
+                    compression_attempted = True
+                    try:
+                        logger.info(
+                            f"Context limit reached with {len(tool_calls) - i} remaining tool calls. "
+                            f"Attempting mid-execution compression..."
+                        )
+
+                        # Trigger mid-execution compression (DB-backed if available, otherwise in-memory)
+                        compression_successful, rebuilt_messages = self._perform_mid_execution_compression(
+                            agent, updated_messages
+                        )
+
+                        if compression_successful and rebuilt_messages is not None:
+                            # Update the messages list with rebuilt compressed version
+                            updated_messages = rebuilt_messages
+
+                            # Yield compression success message
+                            yield {
+                                "type": "info",
+                                "data": {
+                                    "message": "Context window limit reached. Compressed conversation history to continue processing."
+                                }
+                            }
+
+                            logger.info(
+                                f"Mid-execution compression successful. Continuing with {len(tool_calls) - i} remaining tool calls."
+                            )
+                            # Proceed to execute the current tool call with the reduced context
+                        else:
+                            logger.warning("Mid-execution compression attempted but failed. Skipping remaining tools.")
+                    except Exception as e:
+                        logger.error(f"Error during mid-execution compression: {str(e)}", exc_info=True)
+                        compression_attempted = True
+                        compression_successful = False
+
+                # If compression wasn't attempted or failed, skip remaining tools
+                if not compression_successful:
+                    if i == 0:
+                        # Special case: limit reached before executing any tools
+                        # This can happen when previous tool responses pushed context over limit
+                        if compression_attempted:
+                            logger.warning(
+                                f"Context limit reached before executing any tools. "
+                                f"Compression attempted but failed. "
+                                f"Skipping all {len(tool_calls)} pending tool call(s). "
+                                f"This typically occurs when previous tool responses contained large amounts of data."
+                            )
+                        else:
+                            logger.warning(
+                                f"Context limit reached before executing any tools. "
+                                f"Skipping all {len(tool_calls)} pending tool call(s). "
+                                f"This typically occurs when previous tool responses contained large amounts of data. "
+                                f"Consider enabling compression or using a model with larger context window."
+                            )
+                    else:
+                        # Normal case: executed some tools, now stopping
+                        tool_word = "tool call" if i == 1 else "tool calls"
+                        remaining = len(tool_calls) - i
+                        remaining_word = "tool call" if remaining == 1 else "tool calls"
+                        if compression_attempted:
+                            logger.warning(
+                                f"Context limit reached after executing {i} {tool_word}. "
+                                f"Compression attempted but failed. "
+                                f"Skipping remaining {remaining} {remaining_word}."
+                            )
+                        else:
+                            logger.warning(
+                                f"Context limit reached after executing {i} {tool_word}. "
+                                f"Skipping remaining {remaining} {remaining_word}. "
+                                f"Consider enabling compression or using a model with larger context window."
+                            )
+
+                    # Mark remaining tools as skipped
+                    for remaining_call in tool_calls[i:]:
+                        skip_message = {
+                            "type": "tool_call",
+                            "data": {
+                                "tool_name": "system",
+                                "call_id": remaining_call.id,
+                                "action_name": remaining_call.name,
+                                "arguments": {},
+                                "result": "Skipped: Context limit reached. Too many tool calls in conversation.",
+                                "status": "skipped"
+                            }
+                        }
+                        yield skip_message
+
+                    # Set flag on agent
+                    agent.context_limit_reached = True
+                    break
             try:
                 self.tool_calls.append(call)
                 tool_executor_gen = agent._execute_tool_action(tools_dict, call)
@@ -205,21 +710,26 @@ class LLMHandler(ABC):
                     except StopIteration as e:
                         tool_response, call_id = e.value
                         break
+                    
+                function_call_content = {
+                    "function_call": {
+                        "name": call.name,
+                        "args": call.arguments,
+                        "call_id": call_id,
+                    }
+                }
+                # Include thought_signature for Google Gemini 3 models
+                # It should be at the same level as function_call, not inside it
+                if call.thought_signature:
+                    function_call_content["thought_signature"] = call.thought_signature
                 updated_messages.append(
                     {
                         "role": "assistant",
-                        "content": [
-                            {
-                                "function_call": {
-                                    "name": call.name,
-                                    "args": call.arguments,
-                                    "call_id": call_id,
-                                }
-                            }
-                        ],
+                        "content": [function_call_content],
                     }
                 )
 
+
                 updated_messages.append(self.create_tool_message(call, tool_response))
             except Exception as e:
                 logger.error(f"Error executing tool: {str(e)}", exc_info=True)
@@ -324,6 +834,9 @@ class LLMHandler(ABC):
                             existing.name = call.name
                         if call.arguments:
                             existing.arguments += call.arguments
+                        # Preserve thought_signature for Google Gemini 3 models
+                        if call.thought_signature:
+                            existing.thought_signature = call.thought_signature
             if parsed.finish_reason == "tool_calls":
                 tool_handler_gen = self.handle_tool_calls(
                     agent, list(tool_calls.values()), tools_dict, messages
@@ -336,8 +849,21 @@ class LLMHandler(ABC):
                         break
                 tool_calls = {}
 
+                # Check if context limit was reached during tool execution
+                if hasattr(agent, 'context_limit_reached') and agent.context_limit_reached:
+                    # Add system message warning about context limit
+                    messages.append({
+                        "role": "system",
+                        "content": (
+                            "WARNING: Context window limit has been reached. "
+                            "Please provide a final response to the user without making additional tool calls. "
+                            "Summarize the work completed so far."
+                        )
+                    })
+                    logger.info("Context limit reached - instructing agent to wrap up")
+
                 response = agent.llm.gen_stream(
-                    model=agent.model_id, messages=messages, tools=agent.tools
+                    model=agent.model_id, messages=messages, tools=agent.tools if not agent.context_limit_reached else None
                 )
                 self.llm_calls.append(build_stack_data(agent.llm))
 

application/llm/handlers/google.py

@@ -19,15 +19,20 @@ class GoogleLLMHandler(LLMHandler):
             )
         if hasattr(response, "candidates"):
             parts = response.candidates[0].content.parts if response.candidates else []
-            tool_calls = [
-                ToolCall(
-                    id=str(uuid.uuid4()),
-                    name=part.function_call.name,
-                    arguments=part.function_call.args,
-                )
-                for part in parts
-                if hasattr(part, "function_call") and part.function_call is not None
-            ]
+            tool_calls = []
+            for idx, part in enumerate(parts):
+                if hasattr(part, "function_call") and part.function_call is not None:
+                    has_sig = hasattr(part, "thought_signature") and part.thought_signature is not None
+                    thought_sig = part.thought_signature if has_sig else None
+                    tool_calls.append(
+                        ToolCall(
+                            id=str(uuid.uuid4()),
+                            name=part.function_call.name,
+                            arguments=part.function_call.args,
+                            index=idx,
+                            thought_signature=thought_sig,
+                        )
+                    )
 
             content = " ".join(
                 part.text
@@ -41,13 +46,17 @@ class GoogleLLMHandler(LLMHandler):
                 raw_response=response,
             )
         else:
+            # This branch handles individual Part objects from streaming responses
             tool_calls = []
-            if hasattr(response, "function_call"):
+            if hasattr(response, "function_call") and response.function_call is not None:
+                has_sig = hasattr(response, "thought_signature") and response.thought_signature is not None
+                thought_sig = response.thought_signature if has_sig else None
                 tool_calls.append(
                     ToolCall(
                         id=str(uuid.uuid4()),
                         name=response.function_call.name,
                         arguments=response.function_call.args,
+                        thought_signature=thought_sig,
                     )
                 )
             return LLMResponse(

application/llm/openai.py

@@ -128,6 +128,10 @@ class OpenAILLM(BaseLLM):
     ):
         messages = self._clean_messages_openai(messages)
 
+        # Convert max_tokens to max_completion_tokens for newer models
+        if "max_tokens" in kwargs:
+            kwargs["max_completion_tokens"] = kwargs.pop("max_tokens")
+
         request_params = {
             "model": model,
             "messages": messages,
@@ -159,6 +163,10 @@ class OpenAILLM(BaseLLM):
     ):
         messages = self._clean_messages_openai(messages)
 
+        # Convert max_tokens to max_completion_tokens for newer models
+        if "max_tokens" in kwargs:
+            kwargs["max_completion_tokens"] = kwargs.pop("max_tokens")
+
         request_params = {
             "model": model,
             "messages": messages,

application/prompts/compression/v1.0.txt

@@ -0,0 +1,35 @@
+Your task is to create a detailed summary of the conversation so far, paying close attention to the user's explicit requests and your previous actions.
+
+This summary should be thorough in capturing technical details, code patterns, and architectural decisions that would be essential for continuing work without losing context.
+
+Before providing your final summary, wrap your analysis in <analysis> tags to organize your thoughts and ensure you've covered all necessary points. In your analysis process:
+
+1. Chronologically analyze each message, tool call and section of the conversation. For each section thoroughly identify:
+   - The user's explicit requests and intents
+   - Your approach to addressing the user's requests
+   - Key decisions, concepts and patterns
+   - Specific details like if applicable:
+     - file names
+     - full code snippets
+     - function signatures
+     - file edits
+   - Errors that you ran into and how you fixed them
+   - Pay special attention to specific user feedback that you received, especially if the user told you to do something differently.
+
+2. Double-check for accuracy and completeness, addressing each required element thoroughly.
+
+Your summary should include the following sections:
+
+1. Primary Request and Intent: Capture all of the user's explicit requests and intents in detail
+2. Key Concepts: List all important concepts discussed.
+3. Files and Code Sections: Enumerate specific files and code sections examined, modified, or created. Pay special attention to the most recent messages and include full code snippets where applicable and include a summary of why this file read or edit is important.
+4. Errors and fixes: List all errors that you ran into, and how you fixed them. Pay special attention to specific user feedback that you received, especially if the user told you to do something differently.
+5. Problem Solving: Document problems solved and any ongoing troubleshooting efforts.
+6. All user messages: List ALL user messages that are not tool results. These are critical for understanding the users' feedback and changing intent.
+7. Tool Calls: List ALL tool calls made, including their inputs relevant parts of the outputs.
+8. Pending Tasks: Outline any pending tasks that you have explicitly been asked to work on.
+9. Current Work: Describe in detail precisely what was being worked on immediately before this summary request, paying special attention to the most recent messages from both user and assistant. Include file names and code snippets where applicable.
+10. Optional Next Step: List the next step that you will take that is related to the most recent work you were doing. IMPORTANT: ensure that this step is DIRECTLY in line with the user's most recent explicit requests, and the task you were working on immediately before this summary request. If your last task was concluded, then only list next steps if they are explicitly in line with the users request. Do not start on tangential requests or really old requests that were already completed without confirming with the user first.
+If there is a next step, include direct quotes from the most recent conversation showing exactly what task you were working on and where you left off. This should be verbatim to ensure there's no drift in task interpretation.
+
+Please provide your summary based on the conversation and tools used so far, following this structure and ensuring precision and thoroughness in your response.

application/requirements.txt

@@ -15,7 +15,7 @@ Flask==3.1.1
 faiss-cpu==1.9.0.post1
 fastmcp==2.11.0
 flask-restx==1.3.0
-google-genai==1.3.0
+google-genai==1.49.0
 google-api-python-client==2.179.0
 google-auth-httplib2==0.2.0
 google-auth-oauthlib==1.2.2

application/utils.py

@@ -197,6 +197,24 @@ def generate_image_url(image_path):
         return f"{base_url}/api/images/{image_path}"
 
 
+def calculate_compression_threshold(
+    model_id: str, threshold_percentage: float = 0.8
+) -> int:
+    """
+    Calculate token threshold for triggering compression.
+
+    Args:
+        model_id: Model identifier
+        threshold_percentage: Percentage of context window (default 80%)
+
+    Returns:
+        Token count threshold
+    """
+    total_context = get_token_limit(model_id)
+    threshold = int(total_context * threshold_percentage)
+    return threshold
+
+
 def clean_text_for_tts(text: str) -> str:
     """
     clean text for Text-to-Speech processing.

tests/llm/test_google_llm.py

@@ -91,7 +91,7 @@ def test_clean_messages_google_basic():
             {"function_call": {"name": "fn", "args": {"a": 1}}},
         ]},
     ]
-    cleaned = llm._clean_messages_google(msgs)
+    cleaned, system_instruction = llm._clean_messages_google(msgs)
 
     assert all(hasattr(c, "role") and hasattr(c, "parts") for c in cleaned)
     assert any(c.role == "model" for c in cleaned)

tests/test_agent_token_tracking.py

@@ -0,0 +1,325 @@
+import pytest
+from unittest.mock import Mock, patch
+
+from application.agents.base import BaseAgent
+from application.llm.handlers.base import LLMHandler, ToolCall
+
+
+class MockAgent(BaseAgent):
+    """Mock agent for testing"""
+
+    def _gen_inner(self, query, log_context=None):
+        yield {"answer": "test"}
+
+
+@pytest.fixture
+def mock_agent():
+    """Create a mock agent for testing"""
+    agent = MockAgent(
+        endpoint="test",
+        llm_name="openai",
+        model_id="gpt-4o",
+        api_key="test-key",
+    )
+    agent.llm = Mock()
+    return agent
+
+
+@pytest.fixture
+def mock_llm_handler():
+    """Create a mock LLM handler"""
+    handler = Mock(spec=LLMHandler)
+    handler.tool_calls = []
+    return handler
+
+
+class TestAgentTokenTracking:
+    """Test suite for agent token tracking during execution"""
+
+    def test_calculate_current_context_tokens(self, mock_agent):
+        """Test token calculation for current context"""
+        messages = [
+            {"role": "system", "content": "You are a helpful assistant."},
+            {"role": "user", "content": "Hello, how are you?"},
+            {"role": "assistant", "content": "I'm doing well, thank you!"},
+        ]
+
+        tokens = mock_agent._calculate_current_context_tokens(messages)
+
+        # Should count tokens from all messages
+        assert tokens > 0
+        # Rough estimate: ~20-40 tokens for this conversation
+        assert 15 < tokens < 60
+
+    def test_calculate_tokens_with_tool_calls(self, mock_agent):
+        """Test token calculation includes tool call content"""
+        messages = [
+            {"role": "system", "content": "Test"},
+            {
+                "role": "assistant",
+                "content": [
+                    {
+                        "function_call": {
+                            "name": "search_tool",
+                            "args": {"query": "test"},
+                            "call_id": "123",
+                        }
+                    }
+                ],
+            },
+            {
+                "role": "tool",
+                "content": [
+                    {
+                        "function_response": {
+                            "name": "search_tool",
+                            "response": {"result": "Found 10 results"},
+                            "call_id": "123",
+                        }
+                    }
+                ],
+            },
+        ]
+
+        tokens = mock_agent._calculate_current_context_tokens(messages)
+
+        # Should include tool call tokens
+        assert tokens > 0
+
+    @patch("application.core.model_utils.get_token_limit")
+    @patch("application.core.settings.settings")
+    def test_check_context_limit_below_threshold(
+        self, mock_settings, mock_get_token_limit, mock_agent
+    ):
+        """Test context limit check when below threshold"""
+        mock_get_token_limit.return_value = 128000
+        mock_settings.COMPRESSION_THRESHOLD_PERCENTAGE = 0.8
+
+        messages = [
+            {"role": "system", "content": "Short message"},
+            {"role": "user", "content": "Hello"},
+        ]
+
+        # Should return False for small conversation
+        result = mock_agent._check_context_limit(messages)
+        assert result is False
+
+        # Should track current token count
+        assert mock_agent.current_token_count > 0
+        assert mock_agent.current_token_count < 128000 * 0.8
+
+    @patch("application.core.model_utils.get_token_limit")
+    @patch("application.core.settings.settings")
+    def test_check_context_limit_above_threshold(
+        self, mock_settings, mock_get_token_limit, mock_agent
+    ):
+        """Test context limit check when above threshold"""
+        mock_get_token_limit.return_value = 100  # Very small limit for testing
+        mock_settings.COMPRESSION_THRESHOLD_PERCENTAGE = 0.8
+
+        # Create messages that will exceed 80 tokens (80% of 100)
+        messages = [
+            {"role": "system", "content": "a " * 50},  # ~50 tokens
+            {"role": "user", "content": "b " * 50},  # ~50 tokens
+        ]
+
+        # Should return True when exceeding threshold
+        result = mock_agent._check_context_limit(messages)
+        assert result is True
+
+    @patch("application.agents.base.logger")
+    def test_check_context_limit_error_handling(self, mock_logger, mock_agent):
+        """Test error handling in context limit check"""
+        # Force an error by making get_token_limit fail
+        with patch(
+            "application.core.model_utils.get_token_limit", side_effect=Exception("Test error")
+        ):
+            messages = [{"role": "user", "content": "test"}]
+
+            result = mock_agent._check_context_limit(messages)
+
+            # Should return False on error (safe default)
+            assert result is False
+            # Should log the error
+            assert mock_logger.error.called
+
+    def test_context_limit_flag_initialization(self, mock_agent):
+        """Test that context limit flag is initialized"""
+        assert hasattr(mock_agent, "context_limit_reached")
+        assert mock_agent.context_limit_reached is False
+
+        assert hasattr(mock_agent, "current_token_count")
+        assert mock_agent.current_token_count == 0
+
+
+class TestLLMHandlerTokenTracking:
+    """Test suite for LLM handler token tracking"""
+
+    @patch("application.llm.handlers.base.logger")
+    def test_handle_tool_calls_stops_at_limit(self, mock_logger):
+        """Test that tool execution stops when context limit is reached"""
+        from application.llm.handlers.base import LLMHandler
+
+        # Create a concrete handler for testing
+        class TestHandler(LLMHandler):
+            def parse_response(self, response):
+                pass
+
+            def create_tool_message(self, tool_call, result):
+                return {"role": "tool", "content": str(result)}
+
+            def _iterate_stream(self, response):
+                yield ""
+
+        handler = TestHandler()
+
+        # Create mock agent that hits limit on second tool
+        mock_agent = Mock()
+        mock_agent.context_limit_reached = False
+
+        call_count = [0]
+
+        def check_limit_side_effect(messages):
+            call_count[0] += 1
+            # Return True on second call (second tool)
+            return call_count[0] >= 2
+
+        mock_agent._check_context_limit = Mock(side_effect=check_limit_side_effect)
+        mock_agent._execute_tool_action = Mock(
+            return_value=iter([{"type": "tool_call", "data": {}}])
+        )
+
+        # Create multiple tool calls
+        tool_calls = [
+            ToolCall(id="1", name="tool1", arguments={}),
+            ToolCall(id="2", name="tool2", arguments={}),
+            ToolCall(id="3", name="tool3", arguments={}),
+        ]
+
+        messages = []
+        tools_dict = {}
+
+        # Execute tool calls
+        results = list(handler.handle_tool_calls(mock_agent, tool_calls, tools_dict, messages))
+
+        # First tool should execute
+        assert mock_agent._execute_tool_action.call_count == 1
+
+        # Should have yielded skip messages for tools 2 and 3
+        skip_messages = [r for r in results if r.get("type") == "tool_call" and r.get("data", {}).get("status") == "skipped"]
+        assert len(skip_messages) == 2
+
+        # Should have set the flag
+        assert mock_agent.context_limit_reached is True
+
+        # Should have logged warning
+        assert mock_logger.warning.called
+
+    def test_handle_tool_calls_all_execute_when_no_limit(self):
+        """Test that all tools execute when under limit"""
+        from application.llm.handlers.base import LLMHandler
+
+        class TestHandler(LLMHandler):
+            def parse_response(self, response):
+                pass
+
+            def create_tool_message(self, tool_call, result):
+                return {"role": "tool", "content": str(result)}
+
+            def _iterate_stream(self, response):
+                yield ""
+
+        handler = TestHandler()
+
+        # Create mock agent that never hits limit
+        mock_agent = Mock()
+        mock_agent.context_limit_reached = False
+        mock_agent._check_context_limit = Mock(return_value=False)
+        mock_agent._execute_tool_action = Mock(
+            return_value=iter([{"type": "tool_call", "data": {}}])
+        )
+
+        tool_calls = [
+            ToolCall(id="1", name="tool1", arguments={}),
+            ToolCall(id="2", name="tool2", arguments={}),
+            ToolCall(id="3", name="tool3", arguments={}),
+        ]
+
+        messages = []
+        tools_dict = {}
+
+        # Execute tool calls
+        list(handler.handle_tool_calls(mock_agent, tool_calls, tools_dict, messages))
+
+        # All 3 tools should execute
+        assert mock_agent._execute_tool_action.call_count == 3
+
+        # Should not have set the flag
+        assert mock_agent.context_limit_reached is False
+
+    @patch("application.llm.handlers.base.logger")
+    def test_handle_streaming_adds_warning_message(self, mock_logger):
+        """Test that streaming handler adds warning when limit reached"""
+        from application.llm.handlers.base import LLMHandler, LLMResponse, ToolCall
+
+        class TestHandler(LLMHandler):
+            def parse_response(self, response):
+                if isinstance(response, dict) and response.get("type") == "tool_call":
+                    return LLMResponse(
+                        content="",
+                        tool_calls=[ToolCall(id="1", name="test", arguments={}, index=0)],
+                        finish_reason="tool_calls",
+                        raw_response=None,
+                    )
+                else:
+                    return LLMResponse(
+                        content="Done",
+                        tool_calls=[],
+                        finish_reason="stop",
+                        raw_response=None,
+                    )
+
+            def create_tool_message(self, tool_call, result):
+                return {"role": "tool", "content": str(result)}
+
+            def _iterate_stream(self, response):
+                if response == "first":
+                    yield {"type": "tool_call"}  # Object to be parsed, not string
+                else:
+                    yield {"type": "stop"}  # Object to be parsed, not string
+
+        handler = TestHandler()
+
+        # Create mock agent with limit reached
+        mock_agent = Mock()
+        mock_agent.context_limit_reached = True
+        mock_agent.model_id = "gpt-4o"
+        mock_agent.tools = []
+        mock_agent.llm = Mock()
+        mock_agent.llm.gen_stream = Mock(return_value="second")
+
+        def tool_handler_gen(*args):
+            yield {"type": "tool", "data": {}}
+            return []
+
+        # Mock handle_tool_calls to return messages and set flag
+        with patch.object(
+            handler, "handle_tool_calls", return_value=tool_handler_gen()
+        ):
+            messages = []
+            tools_dict = {}
+
+            # Execute streaming
+            list(handler.handle_streaming(mock_agent, "first", tools_dict, messages))
+
+            # Should have called gen_stream with tools=None (disabled)
+            mock_agent.llm.gen_stream.assert_called()
+            call_kwargs = mock_agent.llm.gen_stream.call_args.kwargs
+            assert call_kwargs.get("tools") is None
+
+            # Should have logged the warning
+            assert mock_logger.info.called
+
+
+if __name__ == "__main__":
+    pytest.main([__file__, "-v"])

tests/test_model_validation.py

@@ -0,0 +1,106 @@
+"""
+Tests for model validation and base_url functionality
+"""
+import pytest
+from application.core.model_settings import (
+    AvailableModel,
+    ModelCapabilities,
+    ModelProvider,
+    ModelRegistry,
+)
+from application.core.model_utils import (
+    get_base_url_for_model,
+    validate_model_id,
+)
+
+
+@pytest.mark.unit
+def test_model_with_base_url():
+    """Test that AvailableModel can store and retrieve base_url"""
+    model = AvailableModel(
+        id="test-model",
+        provider=ModelProvider.OPENAI,
+        display_name="Test Model",
+        description="Test model with custom base URL",
+        base_url="https://custom-endpoint.com/v1",
+        capabilities=ModelCapabilities(
+            supports_tools=True,
+            context_window=8192,
+        ),
+    )
+
+    assert model.base_url == "https://custom-endpoint.com/v1"
+    assert model.id == "test-model"
+    assert model.provider == ModelProvider.OPENAI
+
+    # Test to_dict includes base_url
+    model_dict = model.to_dict()
+    assert "base_url" in model_dict
+    assert model_dict["base_url"] == "https://custom-endpoint.com/v1"
+
+
+@pytest.mark.unit
+def test_model_without_base_url():
+    """Test that models without base_url still work"""
+    model = AvailableModel(
+        id="test-model-no-url",
+        provider=ModelProvider.OPENAI,
+        display_name="Test Model",
+        description="Test model without base URL",
+        capabilities=ModelCapabilities(
+            supports_tools=True,
+            context_window=8192,
+        ),
+    )
+
+    assert model.base_url is None
+
+    # Test to_dict doesn't include base_url when None
+    model_dict = model.to_dict()
+    assert "base_url" not in model_dict
+
+
+@pytest.mark.unit
+def test_validate_model_id():
+    """Test model_id validation"""
+    # Get the registry instance to check what models are available
+    ModelRegistry.get_instance()
+
+    # Test with a model that should exist (docsgpt-local is always added)
+    assert validate_model_id("docsgpt-local") is True
+
+    # Test with invalid model_id
+    assert validate_model_id("invalid-model-xyz-123") is False
+
+    # Test with None
+    assert validate_model_id(None) is False
+
+
+@pytest.mark.unit
+def test_get_base_url_for_model():
+    """Test retrieving base_url for a model"""
+    # Test with a model that doesn't have base_url
+    result = get_base_url_for_model("docsgpt-local")
+    assert result is None  # docsgpt-local doesn't have custom base_url
+
+    # Test with invalid model
+    result = get_base_url_for_model("invalid-model")
+    assert result is None
+
+
+@pytest.mark.unit
+def test_model_validation_error_message():
+    """Test that validation provides helpful error messages"""
+    from application.api.answer.services.stream_processor import StreamProcessor
+
+    # Create processor with invalid model_id
+    data = {"model_id": "invalid-model-xyz"}
+    processor = StreamProcessor(data, None)
+
+    # Should raise ValueError with helpful message
+    with pytest.raises(ValueError) as exc_info:
+        processor._validate_and_set_model()
+
+    error_msg = str(exc_info.value)
+    assert "Invalid model_id 'invalid-model-xyz'" in error_msg
+    assert "Available models:" in error_msg

tests/test_token_management.py

@@ -0,0 +1,314 @@
+"""
+Tests for token management and compression features.
+
+NOTE: These tests are for future planned features that are not yet implemented.
+They are skipped until the following modules are created:
+- application.compression (DocumentCompressor, HistoryCompressor, etc.)
+- application.core.token_budget (TokenBudgetManager)
+"""
+# ruff: noqa: F821
+import pytest
+
+pytest.skip(
+    "Token management features not yet implemented - planned for future release",
+    allow_module_level=True,
+)
+
+
+class TestTokenBudgetManager:
+    """Test TokenBudgetManager functionality"""
+
+    def test_calculate_budget(self):
+        """Test budget calculation"""
+        manager = TokenBudgetManager(model_id="gpt-4o")
+        budget = manager.calculate_budget()
+
+        assert budget.total_budget > 0
+        assert budget.system_prompt > 0
+        assert budget.chat_history > 0
+        assert budget.retrieved_docs > 0
+
+    def test_measure_usage(self):
+        """Test token usage measurement"""
+        manager = TokenBudgetManager(model_id="gpt-4o")
+
+        usage = manager.measure_usage(
+            system_prompt="You are a helpful assistant.",
+            current_query="What is Python?",
+            chat_history=[
+                {"prompt": "Hello", "response": "Hi there!"},
+                {"prompt": "How are you?", "response": "I'm doing well, thanks!"},
+            ],
+        )
+
+        assert usage.total > 0
+        assert usage.system_prompt > 0
+        assert usage.current_query > 0
+        assert usage.chat_history > 0
+
+    def test_compression_recommendation(self):
+        """Test compression recommendation generation"""
+        manager = TokenBudgetManager(model_id="gpt-4o")
+
+        # Create scenario with excessive history
+        large_history = [
+            {"prompt": f"Question {i}" * 100, "response": f"Answer {i}" * 100}
+            for i in range(100)
+        ]
+
+        budget, usage, recommendation = manager.check_and_recommend(
+            system_prompt="You are a helpful assistant.",
+            current_query="What is Python?",
+            chat_history=large_history,
+        )
+
+        # Should recommend compression
+        assert recommendation.needs_compression()
+        assert recommendation.compress_history
+
+
+class TestHistoryCompressor:
+    """Test HistoryCompressor functionality"""
+
+    def test_sliding_window_compression(self):
+        """Test sliding window compression strategy"""
+        compressor = HistoryCompressor()
+
+        history = [
+            {"prompt": f"Question {i}", "response": f"Answer {i}"} for i in range(20)
+        ]
+
+        compressed, metadata = compressor.compress(
+            history, target_tokens=500, strategy="sliding_window"
+        )
+
+        assert len(compressed) < len(history)
+        assert metadata["original_messages"] == 20
+        assert metadata["compressed_messages"] < 20
+        assert metadata["strategy"] == "sliding_window"
+
+    def test_preserve_tool_calls(self):
+        """Test that tool calls are preserved during compression"""
+        compressor = HistoryCompressor()
+
+        history = [
+            {"prompt": "Question 1", "response": "Answer 1"},
+            {
+                "prompt": "Use a tool",
+                "response": "Tool used",
+                "tool_calls": [{"tool_name": "search", "result": "Found something"}],
+            },
+            {"prompt": "Question 3", "response": "Answer 3"},
+        ]
+
+        compressed, metadata = compressor.compress(
+            history, target_tokens=200, strategy="sliding_window", preserve_tool_calls=True
+        )
+
+        # Tool call message should be preserved
+        has_tool_calls = any("tool_calls" in msg for msg in compressed)
+        assert has_tool_calls
+
+
+class TestDocumentCompressor:
+    """Test DocumentCompressor functionality"""
+
+    def test_rerank_compression(self):
+        """Test re-ranking compression strategy"""
+        compressor = DocumentCompressor()
+
+        docs = [
+            {"text": f"Document {i} with some content here" * 20, "title": f"Doc {i}"}
+            for i in range(10)
+        ]
+
+        compressed, metadata = compressor.compress(
+            docs, target_tokens=500, query="Document 5", strategy="rerank"
+        )
+
+        assert len(compressed) < len(docs)
+        assert metadata["original_docs"] == 10
+        assert metadata["strategy"] == "rerank"
+
+    def test_excerpt_extraction(self):
+        """Test excerpt extraction strategy"""
+        compressor = DocumentCompressor()
+
+        docs = [
+            {
+                "text": "This is a long document. " * 100
+                + "Python is great. "
+                + "More text here. " * 100,
+                "title": "Python Guide",
+            }
+        ]
+
+        compressed, metadata = compressor.compress(
+            docs, target_tokens=300, query="Python", strategy="excerpt"
+        )
+
+        assert metadata["excerpts_created"] > 0
+        # Excerpt should contain the query term
+        assert "python" in compressed[0]["text"].lower()
+
+
+class TestToolResultCompressor:
+    """Test ToolResultCompressor functionality"""
+
+    def test_truncate_large_results(self):
+        """Test truncation of large tool results"""
+        compressor = ToolResultCompressor()
+
+        tool_results = [
+            {
+                "tool_name": "search",
+                "result": "Very long result " * 1000,
+                "arguments": {},
+            }
+        ]
+
+        compressed, metadata = compressor.compress(
+            tool_results, target_tokens=100, strategy="truncate"
+        )
+
+        assert metadata["results_truncated"] > 0
+        # Result should be shorter
+        compressed_result_len = len(str(compressed[0]["result"]))
+        original_result_len = len(tool_results[0]["result"])
+        assert compressed_result_len < original_result_len
+
+    def test_extract_json_fields(self):
+        """Test extraction of key fields from JSON results"""
+        compressor = ToolResultCompressor()
+
+        tool_results = [
+            {
+                "tool_name": "api_call",
+                "result": {
+                    "data": {"important": "value"},
+                    "metadata": {"verbose": "information" * 100},
+                    "debug": {"lots": "of data" * 100},
+                },
+                "arguments": {},
+            }
+        ]
+
+        compressed, metadata = compressor.compress(
+            tool_results, target_tokens=100, strategy="extract"
+        )
+
+        # Should keep important fields, discard verbose ones
+        assert "data" in compressed[0]["result"]
+
+
+class TestPromptOptimizer:
+    """Test PromptOptimizer functionality"""
+
+    def test_compress_tool_descriptions(self):
+        """Test compression of tool descriptions"""
+        optimizer = PromptOptimizer()
+
+        tools = [
+            {
+                "type": "function",
+                "function": {
+                    "name": f"tool_{i}",
+                    "description": "This is a very long description " * 50,
+                    "parameters": {},
+                },
+            }
+            for i in range(10)
+        ]
+
+        optimized, metadata = optimizer.optimize_tools(
+            tools, target_tokens=500, strategy="compress"
+        )
+
+        assert metadata["optimized_tokens"] < metadata["original_tokens"]
+        assert metadata["descriptions_compressed"] > 0
+
+    def test_lazy_load_tools(self):
+        """Test lazy loading of tools based on query"""
+        optimizer = PromptOptimizer()
+
+        tools = [
+            {
+                "type": "function",
+                "function": {
+                    "name": "search_tool",
+                    "description": "Search for information",
+                    "parameters": {},
+                },
+            },
+            {
+                "type": "function",
+                "function": {
+                    "name": "calculate_tool",
+                    "description": "Perform calculations",
+                    "parameters": {},
+                },
+            },
+            {
+                "type": "function",
+                "function": {
+                    "name": "other_tool",
+                    "description": "Do something else",
+                    "parameters": {},
+                },
+            },
+        ]
+
+        optimized, metadata = optimizer.optimize_tools(
+            tools, target_tokens=200, query="I want to search for something", strategy="lazy_load"
+        )
+
+        # Should prefer search tool
+        assert len(optimized) < len(tools)
+        tool_names = [t["function"]["name"] for t in optimized]
+        # Search tool should be included due to query relevance
+        assert any("search" in name for name in tool_names)
+
+
+def test_integration_compression_workflow():
+    """Test complete compression workflow"""
+    # Simulate a scenario with large inputs
+    manager = TokenBudgetManager(model_id="gpt-4o")
+    history_compressor = HistoryCompressor()
+    doc_compressor = DocumentCompressor()
+
+    # Large chat history
+    history = [
+        {"prompt": f"Question {i}" * 50, "response": f"Answer {i}" * 50}
+        for i in range(50)
+    ]
+
+    # Large documents
+    docs = [
+        {"text": f"Document {i} content" * 100, "title": f"Doc {i}"} for i in range(20)
+    ]
+
+    # Check budget
+    budget, usage, recommendation = manager.check_and_recommend(
+        system_prompt="You are a helpful assistant.",
+        current_query="What is Python?",
+        chat_history=history,
+        retrieved_docs=docs,
+    )
+
+    # Should need compression
+    assert recommendation.needs_compression()
+
+    # Apply compression
+    if recommendation.compress_history:
+        compressed_history, hist_meta = history_compressor.compress(
+            history, recommendation.target_history_tokens or budget.chat_history
+        )
+        assert len(compressed_history) < len(history)
+
+    if recommendation.compress_docs:
+        compressed_docs, doc_meta = doc_compressor.compress(
+            docs,
+            recommendation.target_docs_tokens or budget.retrieved_docs,
+            query="Python",
+        )
+        assert len(compressed_docs) < len(docs)