fix: switch FastAPI routes to Pydantic body models for MCP tools/call

The plan's route signatures used query parameters, which worked for direct
HTTP callers and unit tests, but fastapi-mcp's HTTP transport passes
tools/call arguments as a JSON body. dict-typed parameters like
spark_conf arrived as a string and the route returned 422.

Refactor each route to take a single Pydantic body model (saved in
spark_executor/tools/requests.py). Underlying tool functions unchanged.

Integration tests in tests/integration/test_mcp_routes.py now exercise
the full body-based roundtrip (save_connection with spark_conf, prepare
→ list → get, list_connections with empty body).

spark_executor/server.py

@@ -13,6 +13,15 @@ from spark_executor.tools.connections import (
 )
 from spark_executor.tools.kill import kill_job
 from spark_executor.tools.logs import get_job_logs
+from spark_executor.tools.requests import (
+    ConnectionNameRequest,
+    EmptyRequest,
+    GetJobLogsRequest,
+    JobIdRequest,
+    PendingIdRequest,
+    PrepareSubmitJobRequest,
+    SaveConnectionRequest,
+)
 from spark_executor.tools.status import get_job_status
 from spark_executor.tools.submit import (
     cancel_pending_job,
@@ -31,85 +40,72 @@ def health_check():
 
 
 # MCP tool routes. fastapi-mcp discovers these and registers them as MCP tools.
+# Each route takes a single Pydantic body model so tools/call (which sends args
+# as JSON body) works for every tool, including those with dict-typed params
+# like spark_conf.
 
 # --- Pending submission flow (two-step submit) ---
 
 @app.post("/prepare_submit_job")
-def _prepare_submit_job(connection: str, script_path: str, queue: str = "default",
-                        executor_memory: str = "4G", executor_cores: int = 2,
-                        num_executors: int = 2):
-    return prepare_submit_job(
-        connection=connection,
-        script_path=script_path,
-        queue=queue,
-        executor_memory=executor_memory,
-        executor_cores=executor_cores,
-        num_executors=num_executors,
-    )
+def _prepare_submit_job(req: PrepareSubmitJobRequest):
+    return prepare_submit_job(**req.model_dump())
 
 
 @app.post("/confirm_submit_job")
-def _confirm_submit_job(pending_id: str):
-    return confirm_submit_job(pending_id=pending_id)
+def _confirm_submit_job(req: PendingIdRequest):
+    return confirm_submit_job(pending_id=req.pending_id)
 
 
 @app.post("/list_pending_jobs")
-def _list_pending_jobs():
+def _list_pending_jobs(_req: EmptyRequest = EmptyRequest()):
     return list_pending_jobs()
 
 
 @app.post("/get_pending_job")
-def _get_pending_job(pending_id: str):
-    return get_pending_job(pending_id)
+def _get_pending_job(req: PendingIdRequest):
+    return get_pending_job(req.pending_id)
 
 
 @app.post("/cancel_pending_job")
-def _cancel_pending_job(pending_id: str):
-    return cancel_pending_job(pending_id)
+def _cancel_pending_job(req: PendingIdRequest):
+    return cancel_pending_job(req.pending_id)
 
 
 # --- Spark job tools ---
 
 @app.post("/get_job_status")
-def _get_job_status(job_id: str):
-    return get_job_status(job_id)
+def _get_job_status(req: JobIdRequest):
+    return get_job_status(req.job_id)
 
 
 @app.post("/get_job_logs")
-def _get_job_logs(job_id: str, tail_chars: int = 5000):
-    return get_job_logs(job_id, tail_chars=tail_chars)
+def _get_job_logs(req: GetJobLogsRequest):
+    return get_job_logs(req.job_id, tail_chars=req.tail_chars)
 
 
 @app.post("/kill_job")
-def _kill_job(job_id: str):
-    return kill_job(job_id)
+def _kill_job(req: JobIdRequest):
+    return kill_job(req.job_id)
 
 
 # --- Connection management tools ---
 
 @app.post("/save_connection")
-def _save_connection(name: str, master: str, deploy_mode: str = "cluster",
-                     yarn_rm_url: str | None = None,
-                     spark_conf: dict[str, str] | None = None):
-    return save_connection(
-        name=name,
-        master=master,
-        deploy_mode=deploy_mode,
-        yarn_rm_url=yarn_rm_url,
-        spark_conf=spark_conf,
-    )
+def _save_connection(req: SaveConnectionRequest):
+    # exclude_none so we don't overwrite the function's default with explicit None
+    return save_connection(**req.model_dump(exclude_none=True))
 
 
 @app.post("/list_connections")
-def _list_connections():
+def _list_connections(_req: EmptyRequest = EmptyRequest()):
     return list_connections()
 
 
 @app.post("/get_connection")
-def _get_connection(name: str):
-    return get_connection(name)
+def _get_connection(req: ConnectionNameRequest):
+    return get_connection(req.name)
 
 
 @app.post("/delete_connection")
-def _delete_connection(name: str):
-    return delete_connection(name)
+def _delete_connection(req: ConnectionNameRequest):
+    return delete_connection(req.name)