Use astimezone, add timezone tests, linting

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Document timestamps include timezone information and satisfy the MCP
+  date-time output schema.
+
 ## [0.82.0] - 2026-09-03
 
 ### Removed

haiku_rag_slim/haiku/rag/store/models/document.py

@@ -34,14 +34,8 @@ class Document(BaseModel):
 
     @field_validator("created_at", "updated_at")
     @classmethod
-    def _assume_utc(cls, value: datetime) -> datetime:
-        """Attach UTC to a timezone-less timestamp instead of leaving it ambiguous.
-
-        A row written before timestamps carried an explicit offset parses back
-        with no tzinfo. Treat it as UTC rather than pass it on naive, which the
-        MCP tools' declared JSON schema rejects as an invalid date-time.
-        """
-        return value if value.tzinfo else value.replace(tzinfo=UTC)
+    def _to_utc(cls, value: datetime) -> datetime:
+        return value if value.tzinfo else value.astimezone(UTC)
 
     def set_docling(self, docling_doc: "DoclingDocument") -> None:
         """Serialize and store a DoclingDocument, splitting structure and pages.

haiku_rag_slim/haiku/rag/store/repositories/document.py

@@ -77,8 +77,12 @@ class DocumentRepository:
             docling_document=doc.docling_document,
             docling_pages=doc.docling_pages,
             docling_version=doc.docling_version,
-            created_at=datetime.fromisoformat(created) if created else datetime.now(UTC),
-            updated_at=datetime.fromisoformat(updated) if updated else datetime.now(UTC),
+            created_at=datetime.fromisoformat(created)
+            if created
+            else datetime.now(UTC),
+            updated_at=datetime.fromisoformat(updated)
+            if updated
+            else datetime.now(UTC),
         )
 
     def _to_documents_record(self, entity: Document, doc_id: str) -> DocumentRecord:

tests/test_document.py

@@ -1,3 +1,7 @@
+import os
+import time
+from datetime import UTC, datetime
+
 import pytest
 
 from haiku.rag.store.engine import Store
@@ -549,3 +553,28 @@ async def test_document_get_by_uri_with_special_characters(
         assert retrieved is not None
         assert retrieved.id == created_doc.id
         assert retrieved.uri == "Hamish and Andy's Gap Year"
+
+
+@pytest.mark.skipif(not hasattr(time, "tzset"), reason="time.tzset is POSIX-only")
+def test_naive_timestamp_is_converted_from_local_time():
+    original_tz = os.environ.get("TZ")
+    os.environ["TZ"] = "Europe/Athens"
+    time.tzset()
+    try:
+        created = datetime(2026, 1, 1, 14, 0, 0)  # January is EET, UTC+2
+        updated = datetime(2026, 1, 1, 14, 30, 0)
+        doc = Document(content="x", created_at=created, updated_at=updated)
+        assert doc.created_at == datetime(2026, 1, 1, 12, 0, 0, tzinfo=UTC)
+        assert doc.updated_at == datetime(2026, 1, 1, 12, 30, 0, tzinfo=UTC)
+    finally:
+        if original_tz is None:
+            os.environ.pop("TZ", None)
+        else:
+            os.environ["TZ"] = original_tz
+        time.tzset()
+
+
+def test_created_at_serializes_with_timezone_offset():
+    doc = Document(content="x")
+    value = doc.model_dump(mode="json")["created_at"]
+    assert datetime.fromisoformat(value).utcoffset() is not None