refactor(net): own live session composition

Extract reset, selection, entered-world, and route construction behind LiveSessionHost while preserving the sole LiveSessionController authority. Retain partial route and subscription cleanup for retry, and replace the embedded ACE-only shortcut with the exact named-retail unsigned skill formula.

Co-authored-by: Codex <codex@openai.com>

tests/AcDream.App.Tests/Net/RetailSkillFormulaTests.cs

@@ -0,0 +1,112 @@
+using AcDream.App.Net;
+using DatReaderWriter.DBObjs;
+using DatReaderWriter.Enums;
+using DatReaderWriter.Types;
+
+namespace AcDream.App.Tests.Net;
+
+public sealed class RetailSkillFormulaTests
+{
+    [Fact]
+    public void ZeroDivisorIsTheOnlyFormulaFailureGate()
+    {
+        SkillFormula invalid = Formula(w: 7, x: 1, y: 1, z: 0);
+        Assert.False(RetailSkillFormula.TryCalculate(invalid, 10u, 20u, out uint invalidResult));
+        Assert.Equal(0u, invalidResult);
+
+        SkillFormula zeroX = Formula(w: 7, x: 0, y: 2, z: 3);
+        Assert.True(RetailSkillFormula.TryCalculate(zeroX, 10u, 4u, out uint validResult));
+        Assert.Equal(5u, validResult);
+    }
+
+    [Theory]
+    [InlineData(9u, 4u, 2u)]
+    [InlineData(10u, 4u, 3u)]
+    [InlineData(11u, 4u, 3u)]
+    [InlineData(12u, 4u, 3u)]
+    public void DivisionRoundsToNearestWithExactHalvesUp(
+        uint numerator,
+        uint divisor,
+        uint expected)
+    {
+        SkillFormula formula = Formula(w: 0, x: 1, y: 0, z: divisor);
+
+        Assert.True(RetailSkillFormula.TryCalculate(
+            formula,
+            numerator,
+            0u,
+            out uint result));
+        Assert.Equal(expected, result);
+    }
+
+    [Fact]
+    public void AdditiveWordIsInsideTheNumerator()
+    {
+        SkillFormula formula = Formula(w: 3, x: 1, y: 1, z: 4);
+
+        Assert.True(RetailSkillFormula.TryCalculate(formula, 4u, 2u, out uint result));
+
+        Assert.Equal(2u, result);
+    }
+
+    [Fact]
+    public void NumeratorUsesUnsignedThirtyTwoBitWrap()
+    {
+        SkillFormula formula = Formula(w: 1, x: 2, y: 0, z: 2);
+
+        Assert.True(RetailSkillFormula.TryCalculate(
+            formula,
+            uint.MaxValue,
+            0u,
+            out uint result));
+
+        Assert.Equal(0x80000000u, result);
+    }
+
+    [Fact]
+    public void SignedDatStorageIsReinterpretedAsRetailUnsignedWords()
+    {
+        SkillFormula formula = Formula(w: -1, x: 0, y: 0, z: 1);
+
+        Assert.True(RetailSkillFormula.TryCalculate(formula, 0u, 0u, out uint result));
+
+        Assert.Equal(uint.MaxValue, result);
+    }
+
+    [Fact]
+    public void LiveResolverLooksUpTheDatFormulaAndTreatsMissingAttributesAsZero()
+    {
+        const uint skillId = 0x345u;
+        const uint firstAttributeId = 1u;
+        const uint secondAttributeId = 2u;
+        var skillTable = new SkillTable();
+        skillTable.Skills.Add((SkillId)skillId, new SkillBase
+        {
+            Formula = new SkillFormula
+            {
+                AdditiveBonus = 1,
+                Attribute1Multiplier = 1,
+                Attribute2Multiplier = 2,
+                Divisor = 3,
+                Attribute1 = (AttributeId)firstAttributeId,
+                Attribute2 = (AttributeId)secondAttributeId,
+            },
+        });
+        var resolver = new LiveSkillCreditResolver(skillTable);
+
+        uint result = resolver.Resolve(
+            skillId,
+            new Dictionary<uint, uint> { [firstAttributeId] = 8u });
+
+        Assert.Equal(3u, result);
+        Assert.Equal(0u, resolver.Resolve(0x999u, new Dictionary<uint, uint>()));
+    }
+
+    private static SkillFormula Formula(int w, int x, int y, uint z) => new()
+    {
+        AdditiveBonus = w,
+        Attribute1Multiplier = x,
+        Attribute2Multiplier = y,
+        Divisor = unchecked((int)z),
+    };
+}