feat(investigations): add event impact and work-order feedback flows

Add isolated burst and pollution impact evidence, parallel work-order workflows, persisted notifications and graph updates.

Checkpoint current code. Known follow-ups remain for large pollution result previews and graceful geometry failure.

tests/unit/test_contaminant_simulation_mcp.py

@@ -0,0 +1,68 @@
+import asyncio
+from contextlib import asynccontextmanager
+from types import SimpleNamespace
+from unittest.mock import AsyncMock
+from uuid import uuid4
+
+import pytest
+from fastapi import HTTPException
+from pydantic import ValidationError
+
+from app.mcp import analysis_service, query_service
+from app.mcp.analysis_models import ContaminantSimulationInput
+from app.mcp.calculation_jobs import should_queue
+from app.mcp.catalog import TOOLS
+
+
+def args(**extra):
+    return ContaminantSimulationInput(context_handle="a" * 43, **({
+        "start_time": "2026-07-16T08:00:00+08:00", "duration": 1800,
+        "output_node_ids": ["Q1"], "source": "Q1", "concentration": 1,
+        "include_impact_coverage": True, "impact_threshold_mg_l": 0.01,
+    } | extra))
+
+
+@pytest.mark.parametrize("extra", [{"impact_threshold_mg_l": -1}, {"impact_threshold_mg_l": float("nan")},
+                                    {"include_impact_coverage": "true"}])
+def test_impact_inputs_reject_invalid_thresholds_and_flags(extra):
+    with pytest.raises(ValidationError): args(**extra)
+
+
+def context(monkeypatch):
+    monkeypatch.setattr(query_service, "permissions_for_context", lambda _: {"simulation.run", "scada.view"})
+    @asynccontextmanager
+    async def routing():
+        yield
+    scope = SimpleNamespace(connection=SimpleNamespace(commit=AsyncMock()),
+        project=SimpleNamespace(project_code="project", project_role="member"), user=SimpleNamespace(username="actor"),
+        simulation_routing=routing)
+    binding = SimpleNamespace(tool_cap=["run_contaminant_simulation"], permission_cap=["simulation.run", "scada.view"],
+        purpose="task_execution", task_id=uuid4(), task_scope_cap=[],
+        replay_context={"knowledge_cutoff": "2026-07-16T08:00:00+08:00"})
+    return scope, binding
+
+
+def test_replay_prediction_can_extend_past_cutoff_without_reading_future_observations(monkeypatch):
+    scope, binding = context(monkeypatch)
+    worker = AsyncMock(return_value={"impact": {"affected_node_count": 2}})
+    monkeypatch.setattr(analysis_service, "calculate_replay_contaminant_simulation", worker)
+    result = asyncio.run(query_service.execute_query(scope, binding, TOOLS["run_contaminant_simulation"], args()))
+    assert result.origin == "synthetic" and result.data["result"]["impact"]["affected_node_count"] == 2
+    assert "预测" in result.data_gaps[0]
+    scope.connection.commit.assert_awaited_once()
+    worker.assert_awaited_once()
+    assert worker.await_args.kwargs == {"network": "project", "username": "actor"}
+    assert should_queue(TOOLS["run_contaminant_simulation"], args())
+
+
+@pytest.mark.parametrize("problem", ["future_start", "no_impact", "reader", "permission"])
+def test_replay_admission_keeps_time_permission_and_reader_boundaries(monkeypatch, problem):
+    scope, binding = context(monkeypatch)
+    parameters = args()
+    if problem == "future_start": parameters = args(start_time="2026-07-16T08:15:00+08:00")
+    if problem == "no_impact": parameters = args(include_impact_coverage=False)
+    if problem == "reader": binding.purpose = "task_reader"
+    if problem == "permission": binding.permission_cap.remove("scada.view")
+    with pytest.raises(HTTPException) as caught:
+        asyncio.run(query_service.authorize_query(scope, binding, TOOLS["run_contaminant_simulation"], parameters))
+    assert caught.value.status_code == (422 if problem in {"future_start", "no_impact"} else 403)