diff --git a/agent/pca.py b/agent/pca.py
new file mode 100644
index 000000000..4937a62a9
--- /dev/null
+++ b/agent/pca.py
@@ -0,0 +1,110 @@
+import json
+import logging
+from dataclasses import dataclass, asdict
+from pathlib import Path
+from typing import Optional
+
+logger = logging.getLogger(__name__)
+
+@dataclass
+class PersonalizedCognitiveProfile:
+    """
+    Represents a personalized cognitive profile for a user.
+    """
+    user_id: str
+    preferred_tone: Optional[str] = None
+    # Add more fields as the PCA evolves
+
+    def to_dict(self) -> dict:
+        return asdict(self)
+
+    @classmethod
+    def from_dict(cls, data: dict) -> "PersonalizedCognitiveProfile":
+        return cls(**data)
+
+def _get_profile_path(user_id: str) -> Path:
+    """
+    Returns the path to the personalized cognitive profile file for a given user.
+    """
+    # Assuming profiles are stored under ~/.hermes/profiles/<user_id>/pca_profile.json
+    # This needs to be integrated with the existing profile system more robustly.
+    from hermes_constants import get_hermes_home
+    hermes_home = get_hermes_home()
+    # Profiles are stored under ~/.hermes/profiles/<profile_name>/pca_profile.json
+    # where profile_name could be the user_id or a derived value.
+    # For now, we'll assume the user_id is the profile name for simplicity.
+    profile_dir = hermes_home / "profiles" / user_id
+    if not profile_dir.is_dir():
+        # Fallback to default HERMES_HOME if no specific user profile dir exists
+        return hermes_home / "pca_profile.json"
+    return profile_dir / "pca_profile.json"
+
+def load_cognitive_profile(user_id: str) -> Optional[PersonalizedCognitiveProfile]:
+    """
+    Loads the personalized cognitive profile for a user.
+    """
+    profile_path = _get_profile_path(user_id)
+    if not profile_path.exists():
+        return None
+    try:
+        with open(profile_path, "r", encoding="utf-8") as f:
+            data = json.load(f)
+            return PersonalizedCognitiveProfile.from_dict(data)
+    except Exception as e:
+        logger.warning(f"Failed to load cognitive profile for user {user_id}: {e}")
+        return None
+
+def save_cognitive_profile(profile: PersonalizedCognitiveProfile) -> None:
+    """
+    Saves the personalized cognitive profile for a user.
+    """
+    profile_path = _get_profile_path(profile.user_id)
+    profile_path.parent.mkdir(parents=True, exist_ok=True)
+    try:
+        with open(profile_path, "w", encoding="utf-8") as f:
+            json.dump(profile.to_dict(), f, indent=2, ensure_ascii=False)
+    except Exception as e:
+        logger.error(f"Failed to save cognitive profile for user {profile.user_id}: {e}")
+
+def _get_sessions_by_user_id(db, user_id: str) -> list[dict]:
+    """Helper to get sessions for a specific user_id from SessionDB."""
+    def _do(conn):
+        cursor = conn.execute(
+            "SELECT id FROM sessions WHERE user_id = ? ORDER BY started_at DESC",
+            (user_id,)
+        )
+        return [row["id"] for row in cursor.fetchall()]
+    return db._execute_read(_do)
+
+def analyze_interactions(user_id: str) -> Optional[PersonalizedCognitiveProfile]:
+    """
+    Analyzes historical interactions for a user to infer their cognitive profile.
+    This is a placeholder and will be implemented with actual analysis logic.
+    """
+    logger.info(f"Analyzing interactions for user {user_id}")
+
+    from hermes_state import SessionDB
+    db = SessionDB()
+
+    sessions = _get_sessions_by_user_id(db, user_id)
+    all_messages = []
+    for session_id in sessions:
+        all_messages.extend(db.get_messages_as_conversation(session_id))
+    
+    # Simple heuristic for preferred_tone (placeholder)
+    # In a real implementation, this would involve NLP techniques.
+    preferred_tone = "neutral"
+    if user_id == "Alexander Whitestone": # Example: Replace with actual detection
+        # This is a very simplistic example. Real analysis would be complex.
+        # For demonstration, let's assume Alexander prefers a 'formal' tone
+        # if he has had more than 5 interactions.
+        if len(all_messages) > 5:
+            preferred_tone = "formal"
+        else:
+            preferred_tone = "informal" # Default for less interaction
+    elif "technical" in " ".join([m.get("content", "").lower() for m in all_messages]):
+        preferred_tone = "technical"
+    
+    profile = PersonalizedCognitiveProfile(user_id=user_id, preferred_tone=preferred_tone)
+    save_cognitive_profile(profile)
+    return profile