diff --git a/shell_memory/models.py b/shell_memory/models.py
new file mode 100644
index 0000000..de3c159
--- /dev/null
+++ b/shell_memory/models.py
@@ -0,0 +1,126 @@
+"""Data models for Shell Memory CLI."""
+
+from dataclasses import dataclass, field
+from datetime import datetime
+from typing import List, Optional
+import hashlib
+
+
+@dataclass
+class Command:
+    """Represents a recorded terminal command."""
+    id: Optional[int] = None
+    command: str = ""
+    description: str = ""
+    tags: List[str] = field(default_factory=list)
+    created_at: datetime = field(default_factory=datetime.now)
+    usage_count: int = 0
+
+    def to_dict(self) -> dict:
+        return {
+            "id": self.id,
+            "command": self.command,
+            "description": self.description,
+            "tags": self.tags,
+            "created_at": self.created_at.isoformat(),
+            "usage_count": self.usage_count,
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict) -> "Command":
+        return cls(
+            id=data.get("id"),
+            command=data.get("command", ""),
+            description=data.get("description", ""),
+            tags=data.get("tags", []),
+            created_at=datetime.fromisoformat(data["created_at"]) if "created_at" in data else datetime.now(),
+            usage_count=data.get("usage_count", 0),
+        )
+
+
+@dataclass
+class Pattern:
+    """Represents a detected command pattern."""
+    id: Optional[int] = None
+    name: str = ""
+    command_ids: List[int] = field(default_factory=list)
+    frequency: int = 0
+    last_seen: datetime = field(default_factory=datetime.now)
+
+    def sequence_hash(self) -> str:
+        hash_input = ",".join(map(str, self.command_ids))
+        return hashlib.md5(hash_input.encode()).hexdigest()
+
+    def to_dict(self) -> dict:
+        return {
+            "id": self.id,
+            "name": self.name,
+            "command_ids": self.command_ids,
+            "frequency": self.frequency,
+            "last_seen": self.last_seen.isoformat(),
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict) -> "Pattern":
+        return cls(
+            id=data.get("id"),
+            name=data.get("name", ""),
+            command_ids=data.get("command_ids", []),
+            frequency=data.get("frequency", 0),
+            last_seen=datetime.fromisoformat(data["last_seen"]) if "last_seen" in data else datetime.now(),
+        )
+
+
+@dataclass
+class Session:
+    """Represents a recorded terminal session."""
+    id: Optional[int] = None
+    name: str = ""
+    commands: List[dict] = field(default_factory=list)
+    start_time: datetime = field(default_factory=datetime.now)
+    end_time: Optional[datetime] = None
+
+    def to_dict(self) -> dict:
+        return {
+            "id": self.id,
+            "name": self.name,
+            "commands": self.commands,
+            "start_time": self.start_time.isoformat(),
+            "end_time": self.end_time.isoformat() if self.end_time else None,
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict) -> "Session":
+        return cls(
+            id=data.get("id"),
+            name=data.get("name", ""),
+            commands=data.get("commands", []),
+            start_time=datetime.fromisoformat(data["start_time"]) if "start_time" in data else datetime.now(),
+            end_time=datetime.fromisoformat(data["end_time"]) if data.get("end_time") else None,
+        )
+
+
+@dataclass
+class ScriptTemplate:
+    """Represents a script template for natural language generation."""
+    id: Optional[int] = None
+    keywords: List[str] = field(default_factory=list)
+    template: str = ""
+    description: str = ""
+
+    def to_dict(self) -> dict:
+        return {
+            "id": self.id,
+            "keywords": self.keywords,
+            "template": self.template,
+            "description": self.description,
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict) -> "ScriptTemplate":
+        return cls(
+            id=data.get("id"),
+            keywords=data.get("keywords", []),
+            template=data.get("template", ""),
+            description=data.get("description", ""),
+        )
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