feat(server): integrate MCP queries and investigation messaging

Add project-bound OAuth MCP queries and controlled analysis with scoped evidence,
limits, timeouts and a nearby-model spatial query using EPSG:4326 inputs.
Default nearby searches to 200 meters and five results.

Integrate investigation messaging/presentation, health/readiness and typed history;
remove duplicate web search and fix online simulation and compressed baseline writes.
Include project migrations 023-025; keep local credentials and demo seeding excluded.

Validation: 319 focused pytest checks; real PostGIS temporary-table regression;
read-only Jinqian bridge radius comparison; cross-language MCP discovery/calls.

tests/unit/test_realtime_repository.py

@@ -2,9 +2,16 @@ import asyncio
 from contextlib import asynccontextmanager, contextmanager
 from datetime import datetime, timezone
 
+import pytest
+from pydantic import ValidationError
+
+from app.core.config import Settings, settings
 from app.infra.db.timescaledb.repositories.realtime import RealtimeRepository
 
 
+SNAPSHOT_BUDGET_SQL = "SELECT set_config('timescaledb.max_tuples_decompressed_per_dml_transaction', %s, true)"
+
+
 class _FakeCursor:
     def __init__(self):
         self.calls: list[tuple[str, tuple]] = []
@@ -113,10 +120,12 @@ def test_realtime_node_and_link_replacement_share_outer_transaction(monkeypatch)
     assert conn.transactions == 1
     assert calls == ["nodes", "links"]
     assert [query for query, _params in conn.calls] == [
+        SNAPSHOT_BUDGET_SQL,
         "SELECT pg_advisory_xact_lock(hashtextextended(%s::text, 1))",
         "DELETE FROM realtime.node_results WHERE time = %s",
         "DELETE FROM realtime.link_results WHERE time = %s",
     ]
+    assert conn.calls[0][1] == (str(settings.TIMESCALEDB_REALTIME_MAX_DECOMPRESSED_TUPLES),)
 
 
 def test_realtime_batch_rejects_multiple_timestamps_before_writing():
@@ -170,7 +179,36 @@ def test_empty_realtime_side_is_deleted_as_part_of_snapshot_replacement():
     )
 
     assert [query for query, _params in conn.calls] == [
+        SNAPSHOT_BUDGET_SQL,
         "SELECT pg_advisory_xact_lock(hashtextextended(%s::text, 1))",
         "DELETE FROM realtime.node_results WHERE time = %s",
         "DELETE FROM realtime.link_results WHERE time = %s",
     ]
+
+
+@pytest.mark.parametrize("side", ["nodes", "links"])
+@pytest.mark.parametrize("asynchronous", [False, True])
+def test_all_snapshot_batch_writers_use_configured_local_budget(monkeypatch, side, asynchronous):
+    monkeypatch.setattr(settings, "TIMESCALEDB_REALTIME_MAX_DECOMPRESSED_TUPLES", 1_200_000)
+    conn = _AsyncEmptySnapshotConnection() if asynchronous else _SyncTransactionConnection()
+    if asynchronous:
+        async def copy(*_):
+            pass
+        monkeypatch.setattr(RealtimeRepository, f"_copy_{side}", copy)
+    else:
+        monkeypatch.setattr(RealtimeRepository, f"_copy_{side}_sync", lambda *_: None)
+    method = getattr(RealtimeRepository, f"insert_{side}_batch" + ("" if asynchronous else "_sync"))
+    rows = [{"time": "2026-10-08T04:00:00Z", "id": "fixture"}]
+    if asynchronous:
+        asyncio.run(method(conn, rows))
+    else:
+        method(conn, rows)
+    assert conn.calls[0] == (SNAPSHOT_BUDGET_SQL, ("1200000",))
+    assert "pg_advisory_xact_lock" in conn.calls[1][0]
+    assert conn.calls[2][0].startswith("DELETE FROM realtime.")
+
+
+@pytest.mark.parametrize("value", [0, -1, 2_147_483_648])
+def test_snapshot_budget_must_remain_a_finite_positive_postgres_limit(value):
+    with pytest.raises(ValidationError):
+        Settings(TIMESCALEDB_REALTIME_MAX_DECOMPRESSED_TUPLES=value, _env_file=None)