from typing import List, Optional
from pydantic import BaseModel, Field
from datetime import datetime


class Source(BaseModel):
    type: str
    uri: str
    confidence: Optional[float] = None


class Signal(BaseModel):
    name: str
    value: float
    provenance: Optional[dict] = None


class Provenance(BaseModel):
    trace_id: str
    signer: Optional[str] = None
    ledger_anchor: Optional[str] = None


class NarrativeBlock(BaseModel):
    id: str
    topic: str
    timestamp: datetime
    sources: List[Source] = Field(default_factory=list)
    signals: List[Signal] = Field(default_factory=list)
    sentiment: Optional[float] = None
    risk_factors: List[str] = Field(default_factory=list)
    scenario_flags: List[str] = Field(default_factory=list)
    provenance: Optional[Provenance] = None

    class Config:
        # make JSON serialization deterministic for replay
        json_sort_keys = True