diff --git a/chunks/__init__.py b/chunks/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/chunks/models.py b/chunks/models.py
new file mode 100644
index 0000000..c7a99b3
--- /dev/null
+++ b/chunks/models.py
@@ -0,0 +1,47 @@
+from __future__ import annotations
+from dataclasses import dataclass, field
+
+
+@dataclass
+class Block:
+    id: str
+    kind: str  # paragraph|heading|table|code|list|math|blockquote|html|thematic_break
+    content: str
+    plain_text: str
+    atomic: bool
+    start_line: int
+    end_line: int
+    header_path: list[dict]
+    chars: int
+
+
+@dataclass
+class Chunk:
+    chunk_id: str
+    chunk_index: int
+    content_original: str
+    content_for_embedding: str
+    content_type: str  # section_fragment | atomic_block | overflow
+    chars: int
+    start_line: int
+    end_line: int
+    header_path: list[dict]
+    block_ids: list[str]
+    flags: dict
+    neighbors: dict
+    assets: list = field(default_factory=list)
+
+
+@dataclass
+class Diagnostics:
+    errors: list[str]
+    warnings: list[str]
+    metrics: dict
+
+
+@dataclass
+class ChunkingResult:
+    stem: str
+    source_path: str
+    chunks: list[Chunk]
+    diagnostics: Diagnostics
diff --git a/tests/chunks/test_models.py b/tests/chunks/test_models.py
new file mode 100644
index 0000000..72ec406
--- /dev/null
+++ b/tests/chunks/test_models.py
@@ -0,0 +1,51 @@
+from chunks.models import Block, Chunk, Diagnostics, ChunkingResult
+
+
+def test_block_creation():
+    b = Block(
+        id="blk_0001",
+        kind="paragraph",
+        content="Testo di esempio.",
+        plain_text="Testo di esempio.",
+        atomic=False,
+        start_line=0,
+        end_line=1,
+        header_path=[{"level": 1, "text": "Titolo"}],
+        chars=17,
+    )
+    assert b.id == "blk_0001"
+    assert b.kind == "paragraph"
+    assert not b.atomic
+    assert b.chars == 17
+
+
+def test_chunk_creation():
+    c = Chunk(
+        chunk_id="chk_000001",
+        chunk_index=1,
+        content_original="Testo.",
+        content_for_embedding="Titolo\n\nTesto.",
+        content_type="section_fragment",
+        chars=6,
+        start_line=0,
+        end_line=1,
+        header_path=[{"level": 1, "text": "Titolo"}],
+        block_ids=["blk_0001"],
+        flags={"has_code": False, "has_table": False, "has_math": False,
+               "is_overflow": False, "is_sparse": False},
+        neighbors={"previous_chunk_id": None, "next_chunk_id": None},
+        assets=[],
+    )
+    assert c.chunk_id == "chk_000001"
+    assert c.assets == []
+
+
+def test_diagnostics_empty():
+    d = Diagnostics(errors=[], warnings=[], metrics={})
+    assert d.errors == []
+
+
+def test_chunking_result():
+    r = ChunkingResult(stem="doc", source_path="sources/doc.md", chunks=[], diagnostics=Diagnostics([], [], {}))
+    assert r.stem == "doc"
+    assert r.chunks == []