feat: deterministic JSON schema inference (genson wrapper)

src/auto_reverse/doc/schema.py

@@ -0,0 +1,24 @@
+from __future__ import annotations
+
+from typing import Any
+
+from genson import SchemaBuilder
+
+
+class SchemaAccumulator:
+    """Accumulate JSON samples into a widening JSON Schema (genson-backed)."""
+
+    def __init__(self) -> None:
+        self._builder = SchemaBuilder()
+        self._count = 0
+
+    def add(self, value: Any) -> None:
+        self._builder.add_object(value)
+        self._count += 1
+
+    def schema(self) -> dict[str, Any] | None:
+        if self._count == 0:
+            return None
+        result: dict[str, Any] = self._builder.to_schema()
+        result.pop("$schema", None)
+        return result