diff --git a/plugins/devin/fixtures/devin_sample.json b/plugins/devin/fixtures/devin_sample.json
new file mode 100644
index 0000000..0f522ef
--- /dev/null
+++ b/plugins/devin/fixtures/devin_sample.json
@@ -0,0 +1,21 @@
+{
+  "schema_version": "ATIF-v1.7",
+  "session_id": "demo-001",
+  "steps": [
+    {
+      "source": "user",
+      "message": "Fix the failing NullPointerException in OrderService.persist() in the dutch-kis project",
+      "timestamp": "2026-06-20T10:00:00Z"
+    },
+    {
+      "source": "agent",
+      "message": "The repository call returns an Optional that is being unwrapped with .get(). I'll switch to orElseThrow(NotFoundException::new) so the missing-row case is handled.",
+      "timestamp": "2026-06-20T10:00:05Z"
+    },
+    {
+      "source": "agent",
+      "message": "Applied the fix and ran the suite: rtk mvn test -Dtest=OrderServiceTest -> BUILD SUCCESS, 142 passed, 0 failed.",
+      "timestamp": "2026-06-20T10:01:00Z"
+    }
+  ]
+}
diff --git a/plugins/devin/mcp_server.py b/plugins/devin/mcp_server.py
index 93ea7c2..e5071e3 100644
--- a/plugins/devin/mcp_server.py
+++ b/plugins/devin/mcp_server.py
@@ -36,14 +36,13 @@ import sys
 
 # ── constants ─────────────────────────────────────────────────────────────────
 
-REPO_ROOT = (
+REPO_ROOT = os.path.expanduser(
     os.environ.get("SKILLOPT_SLEEP_REPO")
     or os.path.abspath(os.path.join(os.path.dirname(__file__), "..", ".."))
 )
 PLUGIN_DIR = os.path.dirname(os.path.abspath(__file__))
-CLAUDE_HOME = os.environ.get(
-    "SKILLOPT_DEVIN_CLAUDE_HOME",
-    os.path.expanduser("~/.skillopt-sleep-devin"),
+CLAUDE_HOME = os.path.expanduser(
+    os.environ.get("SKILLOPT_DEVIN_CLAUDE_HOME", "~/.skillopt-sleep-devin")
 )
 MANAGED_SKILL_NAME = os.environ.get("SKILLOPT_MANAGED_SKILL", "skillopt-sleep-learned")
 PROTOCOL_VERSION = "2024-11-05"
diff --git a/tests/test_devin_plugin.py b/tests/test_devin_plugin.py
new file mode 100644
index 0000000..3fa3da9
--- /dev/null
+++ b/tests/test_devin_plugin.py
@@ -0,0 +1,87 @@
+"""Tests for the Devin MCP plugin: tool schema, ATIF-v1.7 harvest, path expansion."""
+import importlib
+import json
+import os
+import sys
+import tempfile
+import unittest
+
+# Allow importing from the plugin directory (mirrors tests/test_mcp_schema.py)
+PLUGIN = os.path.join(os.path.dirname(__file__), "..", "plugins", "devin")
+sys.path.insert(0, PLUGIN)
+
+import mcp_server            # noqa: E402
+import harvest_devin as hw   # noqa: E402
+
+FIXTURES = os.path.join(PLUGIN, "fixtures")
+
+
+def _read_jsonl(path):
+    with open(path, encoding="utf-8") as f:
+        return [json.loads(line) for line in f if line.strip()]
+
+
+def _find_session_jsonl(out_dir):
+    for root, _dirs, files in os.walk(os.path.join(out_dir, "projects")):
+        for name in files:
+            if name.endswith(".jsonl"):
+                return _read_jsonl(os.path.join(root, name))
+    raise AssertionError("no session jsonl written")
+
+
+class TestDevinMcpSchema(unittest.TestCase):
+    def test_tools_are_the_sleep_interface(self):
+        names = {t["name"] for t in mcp_server.TOOLS}
+        self.assertEqual(names, {"sleep_status", "sleep_dry_run", "sleep_run",
+                                 "sleep_adopt", "sleep_harvest"})
+
+    def test_actions_map_to_engine_subcommands(self):
+        expected = {"sleep_status": "status", "sleep_dry_run": "dry-run",
+                    "sleep_run": "run", "sleep_adopt": "adopt",
+                    "sleep_harvest": "harvest"}
+        for t in mcp_server.TOOLS:
+            self.assertEqual(t["action"], expected[t["name"]])
+
+    def test_backends_in_enum(self):
+        backends = mcp_server._TOOL_SCHEMA["properties"]["backend"]["enum"]
+        for b in ["mock", "claude", "codex"]:
+            self.assertIn(b, backends)
+
+
+class TestClaudeHomeExpansion(unittest.TestCase):
+    """Regression: ~ must be expanded even when CLAUDE_HOME comes from the env
+    (the documented mcp-config sets SKILLOPT_DEVIN_CLAUDE_HOME="~/...")."""
+
+    def test_env_tilde_is_expanded(self):
+        os.environ["SKILLOPT_DEVIN_CLAUDE_HOME"] = "~/.skillopt-sleep-devin"
+        try:
+            importlib.reload(mcp_server)
+            self.assertFalse(mcp_server.CLAUDE_HOME.startswith("~"))
+            self.assertEqual(mcp_server.CLAUDE_HOME,
+                             os.path.expanduser("~/.skillopt-sleep-devin"))
+        finally:
+            del os.environ["SKILLOPT_DEVIN_CLAUDE_HOME"]
+            importlib.reload(mcp_server)
+
+
+class TestDevinHarvest(unittest.TestCase):
+    def test_atif_fixture_yields_gradeable_task(self):
+        with tempfile.TemporaryDirectory() as out:
+            n = hw.harvest_devin_transcripts(FIXTURES, out, ["/tmp/proj"])
+            self.assertEqual(n, 1)
+
+            outcomes = _read_jsonl(os.path.join(out, "outcomes.jsonl"))
+            self.assertEqual(len(outcomes), 1)
+            o = outcomes[0]
+            self.assertEqual(o["verifier"], "tests")
+            self.assertTrue(o["success"])
+            self.assertIn("repro", o["reference"])
+
+            # the converted transcript carries the grouping key on the user turn
+            session = _find_session_jsonl(out)
+            user_turn = next(r for r in session if r["type"] == "user")
+            self.assertIn("taskKey", user_turn)
+
+
+if __name__ == "__main__":
+    unittest.main()