diff --git a/backend/artifacts.py b/backend/artifacts.py
new file mode 100644
index 0000000..0bb8e96
--- /dev/null
+++ b/backend/artifacts.py
@@ -0,0 +1,48 @@
+"""Artifact storage module — per-session CRUD operations on the filesystem."""
+
+from pathlib import Path
+
+ARTIFACTS_DIR = Path("/app/artifacts")
+
+
+def list_artifacts(session_id: str) -> list[dict]:
+    """Return sorted list of artifact dicts for a session.
+
+    Each dict contains: name, session_id, size.
+    Returns [] if the session directory does not exist.
+    """
+    session_dir = ARTIFACTS_DIR / session_id
+    if not session_dir.exists():
+        return []
+    return sorted(
+        [
+            {
+                "name": f.name,
+                "session_id": session_id,
+                "size": f.stat().st_size,
+            }
+            for f in session_dir.iterdir()
+            if f.is_file()
+        ],
+        key=lambda d: d["name"],
+    )
+
+
+def get_artifact(session_id: str, name: str) -> str | None:
+    """Return file content (utf-8) or None if the artifact does not exist."""
+    artifact_path = ARTIFACTS_DIR / session_id / name
+    if not artifact_path.exists():
+        return None
+    return artifact_path.read_text(encoding="utf-8")
+
+
+def save_artifact(session_id: str, name: str, content: str) -> Path:
+    """Write content to the artifact file, creating parent dirs as needed.
+
+    Returns the Path of the written file.
+    """
+    session_dir = ARTIFACTS_DIR / session_id
+    session_dir.mkdir(parents=True, exist_ok=True)
+    artifact_path = session_dir / name
+    artifact_path.write_text(content, encoding="utf-8")
+    return artifact_path
diff --git a/tests/test_artifacts.py b/tests/test_artifacts.py
new file mode 100644
index 0000000..dc34106
--- /dev/null
+++ b/tests/test_artifacts.py
@@ -0,0 +1,71 @@
+"""Tests for artifacts module — per-session CRUD storage."""
+
+import sys
+import os
+
+# Add backend to sys.path so we can import artifacts
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", "backend"))
+
+import pytest
+
+import artifacts
+from artifacts import list_artifacts, get_artifact, save_artifact
+
+
+@pytest.fixture(autouse=True)
+def temp_artifacts(tmp_path, monkeypatch):
+    """Redirect ARTIFACTS_DIR to a temp path for test isolation."""
+    monkeypatch.setattr(artifacts, "ARTIFACTS_DIR", tmp_path)
+
+
+def test_list_empty_session():
+    """Returns empty list for an unknown session (no directory)."""
+    result = list_artifacts("session-unknown")
+    assert result == []
+
+
+def test_save_and_list():
+    """Save an artifact then list returns 1 artifact with correct fields."""
+    save_artifact("session-1", "guide.md", "# Guide content")
+    result = list_artifacts("session-1")
+    assert len(result) == 1
+    assert result[0]["name"] == "guide.md"
+    assert result[0]["session_id"] == "session-1"
+
+
+def test_save_and_get():
+    """Save an artifact then get returns the content."""
+    save_artifact("session-1", "notes.txt", "hello world")
+    content = get_artifact("session-1", "notes.txt")
+    assert content == "hello world"
+
+
+def test_get_nonexistent():
+    """get_artifact returns None if file doesn't exist."""
+    result = get_artifact("session-1", "nonexistent.md")
+    assert result is None
+
+
+def test_multiple_artifacts():
+    """2 artifacts for s1, 1 for s2 — list lengths match."""
+    save_artifact("s1", "a.md", "content a")
+    save_artifact("s1", "b.md", "content b")
+    save_artifact("s2", "c.md", "content c")
+
+    s1_list = list_artifacts("s1")
+    s2_list = list_artifacts("s2")
+
+    assert len(s1_list) == 2
+    assert len(s2_list) == 1
+
+
+def test_overwrite_artifact():
+    """Save twice with same name → only 1 artifact, content is the second."""
+    save_artifact("session-1", "doc.md", "first content")
+    save_artifact("session-1", "doc.md", "second content")
+
+    result = list_artifacts("session-1")
+    assert len(result) == 1
+
+    content = get_artifact("session-1", "doc.md")
+    assert content == "second content"