Security resolver and health checker (#2281)

* Setup health check

* Security health checker cron

* Use resolver throughout codebase

* Use resolver for trade builder

* Add security health checks to schedule

* Handle no provider

* Lint fixes

test/models/security/resolver_test.rb

@@ -0,0 +1,78 @@
+require "test_helper"
+
+class Security::ResolverTest < ActiveSupport::TestCase
+  setup do
+    @provider = mock
+    Security.stubs(:provider).returns(@provider)
+  end
+
+  test "resolves DB security" do
+    # Given an existing security in the DB that exactly matches the lookup params
+    db_security = Security.create!(ticker: "TSLA", exchange_operating_mic: "XNAS", country_code: "US")
+
+    # The resolver should return the DB record and never hit the provider
+    Security.expects(:search_provider).never
+
+    resolved = Security::Resolver.new("TSLA", exchange_operating_mic: "XNAS", country_code: "US").resolve
+
+    assert_equal db_security, resolved
+  end
+
+  test "resolves exact provider match" do
+    # Provider returns multiple results, one of which exactly matches symbol + exchange (and country)
+    exact_match = Security.new(ticker: "NVDA", exchange_operating_mic: "XNAS", country_code: "US")
+    near_miss   = Security.new(ticker: "NVDA", exchange_operating_mic: "XNYS", country_code: "US")
+
+    Security.expects(:search_provider)
+            .with("NVDA", exchange_operating_mic: "XNAS", country_code: "US")
+            .returns([ near_miss, exact_match ])
+
+    assert_difference "Security.count", 1 do
+      resolved = Security::Resolver.new("NVDA", exchange_operating_mic: "XNAS", country_code: "US").resolve
+
+      assert resolved.persisted?
+      assert_equal "NVDA", resolved.ticker
+      assert_equal "XNAS", resolved.exchange_operating_mic
+      assert_equal "US",   resolved.country_code
+      refute resolved.offline, "Exact provider matches should not be marked offline"
+    end
+  end
+
+  test "resolves close provider match" do
+    # No exact match – resolver should choose the most relevant close match based on exchange + country ranking
+    preferred = Security.new(ticker: "TEST1", exchange_operating_mic: "XNAS", country_code: "US")
+    other     = Security.new(ticker: "TEST2", exchange_operating_mic: "XNYS", country_code: "GB")
+
+    # Return in reverse-priority order to prove the sorter works
+    Security.expects(:search_provider)
+            .with("TEST", exchange_operating_mic: "XNAS")
+            .returns([ other, preferred ])
+
+    assert_difference "Security.count", 1 do
+      resolved = Security::Resolver.new("TEST", exchange_operating_mic: "XNAS").resolve
+
+      assert resolved.persisted?
+      assert_equal "TEST1", resolved.ticker
+      assert_equal "XNAS",  resolved.exchange_operating_mic
+      assert_equal "US",    resolved.country_code
+      refute resolved.offline, "Provider matches should not be marked offline"
+    end
+  end
+
+  test "resolves offline security" do
+    Security.expects(:search_provider).returns([])
+
+    assert_difference "Security.count", 1 do
+      resolved = Security::Resolver.new("FOO").resolve
+
+      assert resolved.persisted?, "Offline security should be saved"
+      assert_equal "FOO", resolved.ticker
+      assert resolved.offline, "Offline securities should be flagged offline"
+    end
+  end
+
+  test "returns nil when symbol blank" do
+    assert_raises(ArgumentError) { Security::Resolver.new(nil).resolve }
+    assert_raises(ArgumentError) { Security::Resolver.new("").resolve }
+  end
+end