fix: Enforce min_chunk_size in RAG chunker

- Filter out chunks smaller than min_chunk_size (default 100 tokens)
- Exception: Keep all chunks if entire document is smaller than target size
- All 15 tests passing (100% pass rate)

Fixes edge case where very small chunks (e.g., 'Short.' = 6 chars) were
being created despite min_chunk_size=100 setting.

Test: pytest tests/test_rag_chunker.py -v

src/skill_seekers/sync/models.py

@@ -0,0 +1,164 @@
+"""
+Pydantic models for sync system.
+"""
+
+from typing import List, Optional, Dict, Any
+from datetime import datetime
+from enum import Enum
+from pydantic import BaseModel, Field
+
+
+class ChangeType(str, Enum):
+    """Type of change detected."""
+    ADDED = "added"
+    MODIFIED = "modified"
+    DELETED = "deleted"
+    UNCHANGED = "unchanged"
+
+
+class PageChange(BaseModel):
+    """Represents a change to a single page."""
+
+    url: str = Field(..., description="Page URL")
+    change_type: ChangeType = Field(..., description="Type of change")
+    old_hash: Optional[str] = Field(None, description="Previous content hash")
+    new_hash: Optional[str] = Field(None, description="New content hash")
+    diff: Optional[str] = Field(None, description="Content diff (if available)")
+    detected_at: datetime = Field(
+        default_factory=datetime.utcnow,
+        description="When change was detected"
+    )
+
+    class Config:
+        json_schema_extra = {
+            "example": {
+                "url": "https://react.dev/learn/thinking-in-react",
+                "change_type": "modified",
+                "old_hash": "abc123",
+                "new_hash": "def456",
+                "diff": "@@ -10,3 +10,4 @@\n+New content here",
+                "detected_at": "2024-01-15T10:30:00Z"
+            }
+        }
+
+
+class ChangeReport(BaseModel):
+    """Report of all changes detected."""
+
+    skill_name: str = Field(..., description="Skill name")
+    total_pages: int = Field(..., description="Total pages checked")
+    added: List[PageChange] = Field(default_factory=list, description="Added pages")
+    modified: List[PageChange] = Field(default_factory=list, description="Modified pages")
+    deleted: List[PageChange] = Field(default_factory=list, description="Deleted pages")
+    unchanged: int = Field(0, description="Number of unchanged pages")
+    checked_at: datetime = Field(
+        default_factory=datetime.utcnow,
+        description="When check was performed"
+    )
+
+    @property
+    def has_changes(self) -> bool:
+        """Check if any changes were detected."""
+        return bool(self.added or self.modified or self.deleted)
+
+    @property
+    def change_count(self) -> int:
+        """Total number of changes."""
+        return len(self.added) + len(self.modified) + len(self.deleted)
+
+
+class SyncConfig(BaseModel):
+    """Configuration for sync monitoring."""
+
+    skill_config: str = Field(..., description="Path to skill config file")
+    check_interval: int = Field(
+        default=3600,
+        description="Check interval in seconds (default: 1 hour)"
+    )
+    enabled: bool = Field(default=True, description="Whether sync is enabled")
+    auto_update: bool = Field(
+        default=False,
+        description="Automatically rebuild skill on changes"
+    )
+    notify_on_change: bool = Field(
+        default=True,
+        description="Send notifications on changes"
+    )
+    notification_channels: List[str] = Field(
+        default_factory=list,
+        description="Notification channels (email, slack, webhook)"
+    )
+    webhook_url: Optional[str] = Field(
+        None,
+        description="Webhook URL for change notifications"
+    )
+    email_recipients: List[str] = Field(
+        default_factory=list,
+        description="Email recipients for notifications"
+    )
+    slack_webhook: Optional[str] = Field(
+        None,
+        description="Slack webhook URL"
+    )
+
+    class Config:
+        json_schema_extra = {
+            "example": {
+                "skill_config": "configs/react.json",
+                "check_interval": 3600,
+                "enabled": True,
+                "auto_update": False,
+                "notify_on_change": True,
+                "notification_channels": ["slack", "webhook"],
+                "webhook_url": "https://example.com/webhook",
+                "slack_webhook": "https://hooks.slack.com/services/..."
+            }
+        }
+
+
+class SyncState(BaseModel):
+    """Current state of sync monitoring."""
+
+    skill_name: str = Field(..., description="Skill name")
+    last_check: Optional[datetime] = Field(None, description="Last check time")
+    last_change: Optional[datetime] = Field(None, description="Last change detected")
+    total_checks: int = Field(default=0, description="Total checks performed")
+    total_changes: int = Field(default=0, description="Total changes detected")
+    page_hashes: Dict[str, str] = Field(
+        default_factory=dict,
+        description="URL -> content hash mapping"
+    )
+    status: str = Field(default="idle", description="Current status")
+    error: Optional[str] = Field(None, description="Last error message")
+
+
+class WebhookPayload(BaseModel):
+    """Payload for webhook notifications."""
+
+    event: str = Field(..., description="Event type (change_detected, sync_complete)")
+    skill_name: str = Field(..., description="Skill name")
+    timestamp: datetime = Field(
+        default_factory=datetime.utcnow,
+        description="Event timestamp"
+    )
+    changes: Optional[ChangeReport] = Field(None, description="Change report")
+    metadata: Dict[str, Any] = Field(
+        default_factory=dict,
+        description="Additional metadata"
+    )
+
+    class Config:
+        json_schema_extra = {
+            "example": {
+                "event": "change_detected",
+                "skill_name": "react",
+                "timestamp": "2024-01-15T10:30:00Z",
+                "changes": {
+                    "total_pages": 150,
+                    "added": [],
+                    "modified": [{"url": "https://react.dev/learn"}],
+                    "deleted": []
+                },
+                "metadata": {"source": "periodic_check"}
+            }
+        }