feat: add get_job_logs tool with tail

tests/unit/test_logs_tool.py

@@ -0,0 +1,47 @@
+# coding=utf-8
+from datetime import datetime
+from unittest.mock import patch
+
+from spark_executor.core.job_store import JobStore
+from spark_executor.models import Job
+from spark_executor.tools import logs
+
+
+def _seed(job_id="abc", app_id="application_1"):
+    logs.store = JobStore()
+    logs.store.put(
+        Job(
+            job_id=job_id,
+            application_id=app_id,
+            script_path="/tmp/j.py",
+            queue="default",
+            submit_time=datetime(2026, 6, 24),
+            connection="prod",
+        )
+    )
+
+
+def test_get_job_logs_tails_to_default_5000():
+    _seed()
+    big = "x" * 8000 + "\nEND"
+    with patch("spark_executor.tools.logs.get_application_logs", return_value=big):
+        out = logs.get_job_logs("abc")
+    assert out.endswith("END")
+    assert len(out) == 5000
+
+
+def test_get_job_logs_respects_custom_tail_chars():
+    _seed()
+    with patch(
+        "spark_executor.tools.logs.get_application_logs",
+        return_value="0123456789",
+    ):
+        out = logs.get_job_logs("abc", tail_chars=3)
+    assert out == "789"
+
+
+def test_get_job_logs_raises_for_unknown_job():
+    _seed()
+    import pytest
+    with pytest.raises(KeyError):
+        logs.get_job_logs("missing")