Wire in Persona matching to muxing

Closes: #1220

This PR:
- Changes the way the queries are checked to determine if they
match a persona description. Before we were using SQLite now we use Numpy
- Adds a new MuxMatcherType called `persona_description` that checks
if the user messages in a request match a persona description

Author: aponcedeleonch

Diff for: migrations/versions/2025_03_05_2126-e4c05d7591a8_add_installation_table.py

@@ -9,8 +9,6 @@
 from typing import Sequence, Union
 
 from alembic import op
-import sqlalchemy as sa
-
 
 # revision identifiers, used by Alembic.
 revision: str = "e4c05d7591a8"

Diff for: src/codegate/cli.py

@@ -16,8 +16,8 @@
 from codegate.config import Config, ConfigurationError
 from codegate.db.connection import (
     init_db_sync,
-    init_session_if_not_exists,
     init_instance,
+    init_session_if_not_exists,
 )
 from codegate.pipeline.factory import PipelineFactory
 from codegate.pipeline.sensitive_data.manager import SensitiveDataManager

Diff for: src/codegate/config.py

@@ -65,6 +65,9 @@ class Config:
     # The value 0.3 was found through experimentation. See /tests/muxing/test_semantic_router.py
     # It's the threshold value to determine if a persona description is similar to existing personas
     persona_diff_desc_threshold = 0.3
+    # Weight factor for distances in the persona description similarity calculation. Check
+    # the function _weight_distances for more details. Range is [0, 1].
+    distances_weight_factor = 0.8
 
     # Provider URLs with defaults
     provider_urls: Dict[str, str] = field(default_factory=lambda: DEFAULT_PROVIDER_URLS.copy())

Diff for: src/codegate/db/connection.py

@@ -617,7 +617,7 @@ async def init_instance(self) -> None:
             await self._execute_with_no_return(sql, instance.model_dump())
         except IntegrityError as e:
             logger.debug(f"Exception type: {type(e)}")
-            raise AlreadyExistsError(f"Instance already initialized.")
+            raise AlreadyExistsError("Instance already initialized.")
 
 
 class DbReader(DbCodeGate):
@@ -1059,6 +1059,24 @@ async def get_persona_by_name(self, persona_name: str) -> Optional[Persona]:
         )
         return personas[0] if personas else None
 
+    async def get_persona_embed_by_name(self, persona_name: str) -> Optional[PersonaEmbedding]:
+        """
+        Get a persona by name.
+        """
+        sql = text(
+            """
+            SELECT
+                id, name, description, description_embedding
+            FROM personas
+            WHERE name = :name
+            """
+        )
+        conditions = {"name": persona_name}
+        personas = await self._exec_select_conditions_to_pydantic(
+            PersonaEmbedding, sql, conditions, should_raise=True
+        )
+        return personas[0] if personas else None
+
     async def get_distance_to_existing_personas(
         self, query_embedding: np.ndarray, exclude_id: Optional[str]
     ) -> List[PersonaDistance]:
@@ -1086,27 +1104,6 @@ async def get_distance_to_existing_personas(
         )
         return persona_distances
 
-    async def get_distance_to_persona(
-        self, persona_id: str, query_embedding: np.ndarray
-    ) -> PersonaDistance:
-        """
-        Get the distance between a persona and a query embedding.
-        """
-        sql = """
-            SELECT
-                id,
-                name,
-                description,
-                vec_distance_cosine(description_embedding, :query_embedding) as distance
-            FROM personas
-            WHERE id = :id
-        """
-        conditions = {"id": persona_id, "query_embedding": query_embedding}
-        persona_distance = await self._exec_vec_db_query_to_pydantic(
-            sql, conditions, PersonaDistance
-        )
-        return persona_distance[0]
-
     async def get_all_personas(self) -> List[Persona]:
         """
         Get all the personas.

Diff for: src/codegate/muxing/models.py

@@ -32,6 +32,8 @@ class MuxMatcherType(str, Enum):
     fim_filename = "fim_filename"
     # Match based on chat request type. It will match if the request type is chat
     chat_filename = "chat_filename"
+    # Match the request content to the persona description
+    persona_description = "persona_description"
 
 
 class MuxRule(pydantic.BaseModel):

Diff for: src/codegate/muxing/persona.py

@@ -43,6 +43,7 @@ def __init__(self):
         self._n_gpu = conf.chat_model_n_gpu_layers
         self._persona_threshold = conf.persona_threshold
         self._persona_diff_desc_threshold = conf.persona_diff_desc_threshold
+        self._distances_weight_factor = conf.distances_weight_factor
         self._db_recorder = DbRecorder()
         self._db_reader = DbReader()
 
@@ -99,18 +100,17 @@ def _clean_text_for_embedding(self, text: str) -> str:
 
         return text
 
-    async def _embed_text(self, text: str) -> np.ndarray:
+    async def _embed_texts(self, texts: List[str]) -> np.ndarray:
         """
         Helper function to embed text using the inference engine.
         """
-        cleaned_text = self._clean_text_for_embedding(text)
+        cleaned_texts = [self._clean_text_for_embedding(text) for text in texts]
         # .embed returns a list of embeddings
         embed_list = await self._inference_engine.embed(
-            self._embeddings_model, [cleaned_text], n_gpu_layers=self._n_gpu
+            self._embeddings_model, cleaned_texts, n_gpu_layers=self._n_gpu
         )
-        # Use only the first entry in the list and make sure we have the appropriate type
-        logger.debug("Text embedded in semantic routing", text=cleaned_text[:50])
-        return np.array(embed_list[0], dtype=np.float32)
+        logger.debug("Text embedded in semantic routing", num_texts=len(texts))
+        return np.array(embed_list, dtype=np.float32)
 
     async def _is_persona_description_diff(
         self, emb_persona_desc: np.ndarray, exclude_id: Optional[str]
@@ -142,7 +142,8 @@ async def _validate_persona_description(
         Validate the persona description by embedding the text and checking if it is
         different enough from existing personas.
         """
-        emb_persona_desc = await self._embed_text(persona_desc)
+        emb_persona_desc_list = await self._embed_texts([persona_desc])
+        emb_persona_desc = emb_persona_desc_list[0]
         if not await self._is_persona_description_diff(emb_persona_desc, exclude_id):
             raise PersonaSimilarDescriptionError(
                 "The persona description is too similar to existing personas."
@@ -217,21 +218,87 @@ async def delete_persona(self, persona_name: str) -> None:
         await self._db_recorder.delete_persona(persona.id)
         logger.info(f"Deleted persona {persona_name} from the database.")
 
-    async def check_persona_match(self, persona_name: str, query: str) -> bool:
+    async def _get_cosine_distance(self, emb_queries: np.ndarray, emb_persona: np.ndarray) -> float:
         """
-        Check if the query matches the persona description. A vector similarity
-        search is performed between the query and the persona description.
+        Calculate the cosine distance between the queries embeddings and persona embedding.
+        Persona embedding is a single vector of length M
+        Queries embeddings is a matrix of shape (N, M)
+        N is the number of queries. User messages in this case.
+        M is the number of dimensions in the embedding
+
+        Defintion of cosine distance: 1 - cosine similarity
+        [Cosine similarity](https://en.wikipedia.org/wiki/Cosine_similarity)
+
+        NOTE: Experimented by individually querying SQLite for each query, but as the number
+        of queries increases, the performance is better with NumPy. If the number of queries
+        is small the performance is onpar. Hence the decision to use NumPy.
+        """
+        # Handle the case where we have a single query (single user message)
+        if emb_queries.ndim == 1:
+            emb_queries = emb_queries.reshape(1, -1)
+
+        emb_queries_norm = np.linalg.norm(emb_queries, axis=1)
+        persona_embed_norm = np.linalg.norm(emb_persona)
+        cosine_similarities = np.dot(emb_queries, emb_persona.T) / (
+            emb_queries_norm * persona_embed_norm
+        )
+        # We could also use directly cosine_similarities but we get the distance to match
+        # the behavior of SQLite function vec_distance_cosine
+        cosine_distances = 1 - cosine_similarities
+        return cosine_distances
+
+    async def _weight_distances(self, distances: np.ndarray) -> np.ndarray:
+        """
+        Weights the received distances, with later positions being more important and the
+        last position unchanged. The reasoning is that the distances correspond to user
+        messages, with the last message being the most recent and therefore the most
+        important.
+
+        Args:
+            distances: NumPy array of float values between 0 and 2
+            weight_factor: Factor that determines how quickly weights increase (0-1)
+                        Lower values create a steeper importance curve. 1 makes
+                        all weights equal.
+
+        Returns:
+            Weighted distances as a NumPy array
+        """
+        # Get array length
+        n = len(distances)
+
+        # Create positions array in reverse order (n-1, n-2, ..., 1, 0)
+        # This makes the last element have position 0
+        positions = np.arange(n - 1, -1, -1)
+
+        # Create weights - now the last element (position 0) gets weight 1
+        weights = self._distances_weight_factor**positions
+
+        # Apply weights by dividing distances
+        # Smaller weight -> larger effective distance
+        weighted_distances = distances / weights
+        return weighted_distances
+
+    async def check_persona_match(self, persona_name: str, queries: List[str]) -> bool:
+        """
+        Check if the queries match the persona description. A vector similarity
+        search is performed between the queries and the persona description.
         0 means the vectors are identical, 2 means they are orthogonal.
-        See
-        [sqlite docs](https://alexgarcia.xyz/sqlite-vec/api-reference.html#vec_distance_cosine)
+
+        The vectors are compared using cosine similarity implemented in _get_cosine_distance.
         """
-        persona = await self._db_reader.get_persona_by_name(persona_name)
-        if not persona:
+        persona_embed = await self._db_reader.get_persona_embed_by_name(persona_name)
+        if not persona_embed:
             raise PersonaDoesNotExistError(f"Persona {persona_name} does not exist.")
 
-        emb_query = await self._embed_text(query)
-        persona_distance = await self._db_reader.get_distance_to_persona(persona.id, emb_query)
-        logger.info(f"Persona distance to {persona_name}", distance=persona_distance.distance)
-        if persona_distance.distance < self._persona_threshold:
+        emb_queries = await self._embed_texts(queries)
+        cosine_distances = await self._get_cosine_distance(
+            emb_queries, persona_embed.description_embedding
+        )
+        logger.debug("Cosine distances calculated", cosine_distances=cosine_distances)
+
+        weighted_distances = await self._weight_distances(cosine_distances)
+        logger.info("Weighted distances to persona", weighted_distances=weighted_distances)
+
+        if np.any(weighted_distances < self._persona_threshold):
             return True
         return False

Diff for: src/codegate/muxing/rulematcher.py

@@ -11,6 +11,7 @@
 from codegate.extract_snippets.body_extractor import BodyCodeSnippetExtractorError
 from codegate.extract_snippets.factory import BodyCodeExtractorFactory
 from codegate.muxing import models as mux_models
+from codegate.muxing.persona import PersonaManager
 
 logger = structlog.get_logger("codegate")
 
@@ -82,6 +83,7 @@ def create(db_mux_rule: db_models.MuxRule, route: ModelRoute) -> MuxingRuleMatch
             mux_models.MuxMatcherType.filename_match: FileMuxingRuleMatcher,
             mux_models.MuxMatcherType.fim_filename: RequestTypeAndFileMuxingRuleMatcher,
             mux_models.MuxMatcherType.chat_filename: RequestTypeAndFileMuxingRuleMatcher,
+            mux_models.MuxMatcherType.persona_description: PersonaDescriptionMuxingRuleMatcher,
         }
 
         try:
@@ -171,6 +173,48 @@ def match(self, thing_to_match: mux_models.ThingToMatchMux) -> bool:
         return is_rule_matched
 
 
+class PersonaDescriptionMuxingRuleMatcher(MuxingRuleMatcher):
+    """Muxing rule to match the request content to a persona description."""
+
+    def _get_user_messages_from_body(self, body: Dict) -> List[str]:
+        """
+        Get the user messages from the body to use as queries.
+        """
+        user_messages = []
+        for msg in body.get("messages", []):
+            if msg.get("role", "") == "user":
+                msgs_content = msg.get("content")
+                if not msgs_content:
+                    continue
+                if isinstance(msgs_content, list):
+                    for msg_content in msgs_content:
+                        if msg_content.get("type", "") == "text":
+                            user_messages.append(msg_content.get("text", ""))
+                elif isinstance(msgs_content, str):
+                    user_messages.append(msgs_content)
+        return user_messages
+
+    def match(self, thing_to_match: mux_models.ThingToMatchMux) -> bool:
+        """
+        Return True if the matcher is the persona description matched with the
+        user messages.
+        """
+        user_messages = self._get_user_messages_from_body(thing_to_match.body)
+        if not user_messages:
+            return False
+
+        persona_manager = PersonaManager()
+        is_persona_matched = persona_manager.check_persona_match(
+            persona_name=self._mux_rule.matcher, queries=user_messages
+        )
+        logger.info(
+            "Persona rule matched",
+            matcher=self._mux_rule.matcher,
+            is_persona_matched=is_persona_matched,
+        )
+        return is_persona_matched
+
+
 class MuxingRulesinWorkspaces:
     """A thread safe dictionary to store the muxing rules in workspaces."""
 

Diff for: tests/muxing/test_persona.py

@@ -90,7 +90,7 @@ async def test_persona_not_exist_match(semantic_router_mocked_db: PersonaManager
     persona_name = "test_persona"
     query = "test_query"
     with pytest.raises(PersonaDoesNotExistError):
-        await semantic_router_mocked_db.check_persona_match(persona_name, query)
+        await semantic_router_mocked_db.check_persona_match(persona_name, [query])
 
 
 class PersonaMatchTest(BaseModel):
@@ -333,11 +333,39 @@ async def test_check_persona_pass_match(
     # Check for the queries that should pass
     for query in persona_match_test.pass_queries:
         match = await semantic_router_mocked_db.check_persona_match(
-            persona_match_test.persona_name, query
+            persona_match_test.persona_name, [query]
         )
         assert match is True
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "persona_match_test",
+    [
+        simple_persona,
+        architect,
+        coder,
+        devops_sre,
+    ],
+)
+async def test_check_persona_pass_match_vector(
+    semantic_router_mocked_db: PersonaManager, persona_match_test: PersonaMatchTest
+):
+    """Test checking persona match."""
+    await semantic_router_mocked_db.add_persona(
+        persona_match_test.persona_name, persona_match_test.persona_desc
+    )
+
+    # We disable the weighting between distances since these are no user messages that
+    # need to be weighted differently, they all are weighted the same.
+    semantic_router_mocked_db._distances_weight_factor = 1.0
+    # Check for match passing the entire list
+    match = await semantic_router_mocked_db.check_persona_match(
+        persona_match_test.persona_name, persona_match_test.pass_queries
+    )
+    assert match is True
+
+
 @pytest.mark.asyncio
 @pytest.mark.parametrize(
     "persona_match_test",
@@ -359,11 +387,39 @@ async def test_check_persona_fail_match(
     # Check for the queries that should fail
     for query in persona_match_test.fail_queries:
         match = await semantic_router_mocked_db.check_persona_match(
-            persona_match_test.persona_name, query
+            persona_match_test.persona_name, [query]
         )
         assert match is False
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "persona_match_test",
+    [
+        simple_persona,
+        architect,
+        coder,
+        devops_sre,
+    ],
+)
+async def test_check_persona_fail_match_vector(
+    semantic_router_mocked_db: PersonaManager, persona_match_test: PersonaMatchTest
+):
+    """Test checking persona match."""
+    await semantic_router_mocked_db.add_persona(
+        persona_match_test.persona_name, persona_match_test.persona_desc
+    )
+
+    # We disable the weighting between distances since these are no user messages that
+    # need to be weighted differently, they all are weighted the same.
+    semantic_router_mocked_db._distances_weight_factor = 1.0
+    # Check for match passing the entire list
+    match = await semantic_router_mocked_db.check_persona_match(
+        persona_match_test.persona_name, persona_match_test.fail_queries
+    )
+    assert match is False
+
+
 @pytest.mark.asyncio
 @pytest.mark.parametrize(
     "personas",