feat: add OpenHerbarium MCP server core

src/openherbarium_mcp/models.py

@@ -0,0 +1,47 @@
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from typing import Any
+
+Confidence = str
+
+
+def utc_now_iso() -> str:
+    return datetime.now(timezone.utc).isoformat()
+
+
+def evidence(
+    value: Any,
+    *,
+    source: str,
+    url: str | None = None,
+    confidence: Confidence = "medium",
+    retrieved_at: str | None = None,
+    raw: Any | None = None,
+) -> dict[str, Any]:
+    """Wrap a data value with provenance.
+
+    The MCP deliberately returns evidence records rather than editorial recommendations.
+    Hermes or another client remains responsible for interpreting and presenting the data.
+    """
+    record: dict[str, Any] = {
+        "value": value,
+        "source": source,
+        "url": url,
+        "retrieved_at": retrieved_at or utc_now_iso(),
+        "confidence": confidence,
+    }
+    if raw is not None:
+        record["raw"] = raw
+    return record
+
+
+def empty_result(query: str, tool: str, reason: str) -> dict[str, Any]:
+    return {
+        "query": query,
+        "tool": tool,
+        "retrieved_at": utc_now_iso(),
+        "status": "no_data",
+        "reason": reason,
+        "records": [],
+    }