Implement Rolemaster roll execution

README.md

@@ -64,6 +64,8 @@ Gameplay capabilities now include:
 - Admin user management is integrated into workspace screen toggles (`Play`, `Campaign Management`, `Admin`)
 - Rolemaster expression validation currently recognizes `2d10+48`, `d100+4`, and `d100!+85`, including Rolemaster-only negative modifiers such as `d100-15`
 - Rolemaster open-ended percentile skills and skill-group defaults now persist a nullable `FumbleRange` field, while D6 and D&D rows migrate forward unchanged
+- Rolemaster roll execution now supports initiative (`2d10+x`), standard percentile (`d100+x`), and open-ended percentile (`d100!+x`) with recursive high-end chaining and low-end subtraction based on `FumbleRange`
+- Compact campaign-log summaries stay dense for Rolemaster rolls, while lazy-loaded roll detail includes ordered die metadata for each open-ended follow-up step
 - Startup migration coverage is validated against a copied temp-file instance of `RpgRoller/App_Data/rpgroller.development.db` before feature work is considered complete
 
 ## Prerequisites

RpgRoller.Tests/Api/RolemasterApiTests.cs

@@ -0,0 +1,88 @@
+namespace RpgRoller.Tests;
+
+public sealed class RolemasterApiTests : ApiTestBase
+{
+    public RolemasterApiTests(WebApplicationFactory<Program> factory) : base(factory)
+    {
+    }
+
+    [Fact]
+    public async Task RolemasterRollEndpoints_ExecuteInitiativeAndPercentile()
+    {
+        using var factory = CreateFactory(8, 6, 74);
+        using var client = factory.CreateClient(new() { AllowAutoRedirect = false });
+
+        await RegisterAsync(client, "rolemaster-api", "Password123", "Rolemaster Api");
+        await LoginAsync(client, "rolemaster-api", "Password123");
+
+        var campaign = await PostAsync<CreateCampaignRequest, CampaignSummary>(client, "/api/campaigns", new("Rolemaster", "rolemaster"));
+        var character = await PostAsync<CreateCharacterRequest, CharacterSummary>(client, "/api/characters", new("Hero", campaign.Id));
+        var initiative = await PostAsync<CreateSkillRequest, SkillSummary>(client, $"/api/characters/{character.Id}/skills", new("Initiative", "2d10+48", 0, false));
+        var perception = await PostAsync<CreateSkillRequest, SkillSummary>(client, $"/api/characters/{character.Id}/skills", new("Perception", "d100-15", 0, false));
+
+        var initiativeRoll = await PostAsync<RollSkillRequest, RollResult>(client, $"/api/skills/{initiative.Id}/roll", new("public"));
+        var percentileRoll = await PostAsync<RollSkillRequest, RollResult>(client, $"/api/skills/{perception.Id}/roll", new("public"));
+        var logPage = await GetAsync<CampaignLogPage>(client, $"/api/campaigns/{campaign.Id}/log/page?limit=10");
+
+        Assert.Equal(62, initiativeRoll.Result);
+        Assert.Equal("8+6+48=62", initiativeRoll.Breakdown);
+        Assert.All(initiativeRoll.Dice, die => Assert.Equal(RollDieKinds.RolemasterInitiative, die.Kind));
+
+        Assert.Equal(59, percentileRoll.Result);
+        Assert.Equal("74-15=59", percentileRoll.Breakdown);
+        Assert.Equal(RollDieKinds.RolemasterPercentile, Assert.Single(percentileRoll.Dice).Kind);
+
+        Assert.Equal(2, logPage.Entries.Length);
+        Assert.Equal("8 + 6 | initiative", logPage.Entries[0].SummaryText);
+        Assert.Equal("74 | percentile", logPage.Entries[1].SummaryText);
+    }
+
+    [Fact]
+    public async Task RolemasterOpenEndedRolls_AppearInLogPageAndDetail()
+    {
+        using var factory = CreateFactory(5, 97, 100, 12);
+        using var client = factory.CreateClient(new() { AllowAutoRedirect = false });
+
+        await RegisterAsync(client, "rolemaster-open-api", "Password123", "Rolemaster Open Api");
+        await LoginAsync(client, "rolemaster-open-api", "Password123");
+
+        var campaign = await PostAsync<CreateCampaignRequest, CampaignSummary>(client, "/api/campaigns", new("Rolemaster Open", "rolemaster"));
+        var character = await PostAsync<CreateCharacterRequest, CharacterSummary>(client, "/api/characters", new("Hero", campaign.Id));
+        var skill = await PostAsync<CreateSkillRequest, SkillSummary>(client, $"/api/characters/{character.Id}/skills", new("Awareness", "d100!+85", 0, false, null, 5));
+
+        var roll = await PostAsync<RollSkillRequest, RollResult>(client, $"/api/skills/{skill.Id}/roll", new("public"));
+        var logPage = await GetAsync<CampaignLogPage>(client, $"/api/campaigns/{campaign.Id}/log/page?limit=5");
+        var detail = await GetAsync<CampaignRollDetail>(client, $"/api/rolls/{roll.RollId}");
+
+        Assert.Equal(-119, roll.Result);
+        Assert.Equal("5-(97+100+12)+85=-119", roll.Breakdown);
+        Assert.Equal("5 - (97 + 100 + 12) | open-ended low", Assert.Single(logPage.Entries).SummaryText);
+        Assert.Equal(roll.Breakdown, detail.Breakdown);
+        Assert.Collection(
+            detail.Dice,
+            die =>
+            {
+                Assert.Equal(RollDieKinds.RolemasterOpenEndedInitial, die.Kind);
+                Assert.Equal(1, die.Sequence);
+                Assert.Equal(5, die.SignedContribution);
+            },
+            die =>
+            {
+                Assert.Equal(RollDieKinds.RolemasterOpenEndedLowSubtract, die.Kind);
+                Assert.Equal(2, die.Sequence);
+                Assert.Equal(-97, die.SignedContribution);
+            },
+            die =>
+            {
+                Assert.Equal(RollDieKinds.RolemasterOpenEndedLowSubtract, die.Kind);
+                Assert.Equal(3, die.Sequence);
+                Assert.Equal(-100, die.SignedContribution);
+            },
+            die =>
+            {
+                Assert.Equal(RollDieKinds.RolemasterOpenEndedLowSubtract, die.Kind);
+                Assert.Equal(4, die.Sequence);
+                Assert.Equal(-12, die.SignedContribution);
+            });
+    }
+}

RpgRoller.Tests/Services/ServiceRolemasterRollTests.cs

@@ -0,0 +1,164 @@
+namespace RpgRoller.Tests;
+
+public sealed class ServiceRolemasterRollTests
+{
+    [Fact]
+    public void RollSkill_RolemasterInitiative_ComputesTotalAndTagsDice()
+    {
+        using var harness = ServiceTestSupport.CreateHarness(7, 10);
+        var service = harness.Service;
+
+        service.Register("gm-init", "Password123", "GM");
+        var session = ServiceTestSupport.GetValue(service.Login("gm-init", "Password123")).SessionToken;
+        var campaign = ServiceTestSupport.GetValue(service.CreateCampaign(session, "Rolemaster", "rolemaster"));
+        var character = ServiceTestSupport.GetValue(service.CreateCharacter(session, "Hero", campaign.Id));
+        var skill = ServiceTestSupport.GetValue(service.CreateSkill(session, character.Id, "Initiative", "2d10+48", 0, false));
+
+        var roll = ServiceTestSupport.GetValue(service.RollSkill(session, skill.Id, "public"));
+        var logPage = ServiceTestSupport.GetValue(service.GetCampaignLogPage(session, campaign.Id, limit: 5));
+
+        Assert.Equal(65, roll.Result);
+        Assert.Equal("7+10+48=65", roll.Breakdown);
+        Assert.Equal("7 + 10 | initiative", Assert.Single(logPage.Entries).SummaryText);
+        Assert.Collection(
+            roll.Dice,
+            die =>
+            {
+                Assert.Equal(7, die.Roll);
+                Assert.Equal(1, die.Sequence);
+                Assert.Equal(RollDieKinds.RolemasterInitiative, die.Kind);
+                Assert.Equal(7, die.SignedContribution);
+            },
+            die =>
+            {
+                Assert.Equal(10, die.Roll);
+                Assert.Equal(2, die.Sequence);
+                Assert.Equal(RollDieKinds.RolemasterInitiative, die.Kind);
+                Assert.Equal(10, die.SignedContribution);
+            });
+    }
+
+    [Fact]
+    public void RollSkill_RolemasterPercentile_ComputesTotalAndTagsDice()
+    {
+        using var harness = ServiceTestSupport.CreateHarness(73);
+        var service = harness.Service;
+
+        service.Register("gm-percentile", "Password123", "GM");
+        var session = ServiceTestSupport.GetValue(service.Login("gm-percentile", "Password123")).SessionToken;
+        var campaign = ServiceTestSupport.GetValue(service.CreateCampaign(session, "Rolemaster", "rolemaster"));
+        var character = ServiceTestSupport.GetValue(service.CreateCharacter(session, "Hero", campaign.Id));
+        var skill = ServiceTestSupport.GetValue(service.CreateSkill(session, character.Id, "Perception", "d100-15", 0, false));
+
+        var roll = ServiceTestSupport.GetValue(service.RollSkill(session, skill.Id, "public"));
+        var logPage = ServiceTestSupport.GetValue(service.GetCampaignLogPage(session, campaign.Id, limit: 5));
+
+        Assert.Equal(58, roll.Result);
+        Assert.Equal("73-15=58", roll.Breakdown);
+        Assert.Equal("73 | percentile", Assert.Single(logPage.Entries).SummaryText);
+
+        var die = Assert.Single(roll.Dice);
+        Assert.Equal(73, die.Roll);
+        Assert.Equal(1, die.Sequence);
+        Assert.Equal(RollDieKinds.RolemasterPercentile, die.Kind);
+        Assert.Equal(73, die.SignedContribution);
+    }
+
+    [Fact]
+    public void RollSkill_RolemasterOpenEndedHigh_RecursesAndBuildsReadableLogSummary()
+    {
+        using var harness = ServiceTestSupport.CreateHarness(97, 96, 45);
+        var service = harness.Service;
+
+        service.Register("gm-open-high", "Password123", "GM");
+        var session = ServiceTestSupport.GetValue(service.Login("gm-open-high", "Password123")).SessionToken;
+        var campaign = ServiceTestSupport.GetValue(service.CreateCampaign(session, "Rolemaster", "rolemaster"));
+        var character = ServiceTestSupport.GetValue(service.CreateCharacter(session, "Hero", campaign.Id));
+        var skill = ServiceTestSupport.GetValue(service.CreateSkill(session, character.Id, "Awareness", "d100!+85", 0, false, null, 5));
+
+        var roll = ServiceTestSupport.GetValue(service.RollSkill(session, skill.Id, "public"));
+        var detail = ServiceTestSupport.GetValue(service.GetRollDetail(session, roll.RollId));
+        var logPage = ServiceTestSupport.GetValue(service.GetCampaignLogPage(session, campaign.Id, limit: 5));
+
+        Assert.Equal(323, roll.Result);
+        Assert.Equal("97+96+45+85=323", roll.Breakdown);
+        Assert.Equal("97 + 96 + 45 | open-ended high", Assert.Single(logPage.Entries).SummaryText);
+        Assert.Equal(roll.Breakdown, detail.Breakdown);
+        Assert.Collection(
+            detail.Dice,
+            die =>
+            {
+                Assert.Equal(97, die.Roll);
+                Assert.Equal(1, die.Sequence);
+                Assert.Equal(RollDieKinds.RolemasterOpenEndedInitial, die.Kind);
+                Assert.Equal(97, die.SignedContribution);
+                Assert.False(die.Added);
+            },
+            die =>
+            {
+                Assert.Equal(96, die.Roll);
+                Assert.Equal(2, die.Sequence);
+                Assert.Equal(RollDieKinds.RolemasterOpenEndedHigh, die.Kind);
+                Assert.Equal(96, die.SignedContribution);
+                Assert.True(die.Added);
+            },
+            die =>
+            {
+                Assert.Equal(45, die.Roll);
+                Assert.Equal(3, die.Sequence);
+                Assert.Equal(RollDieKinds.RolemasterOpenEndedHigh, die.Kind);
+                Assert.Equal(45, die.SignedContribution);
+                Assert.True(die.Added);
+            });
+    }
+
+    [Fact]
+    public void RollSkill_RolemasterOpenEndedLow_SubtractsRecursiveHighChain()
+    {
+        using var harness = ServiceTestSupport.CreateHarness(5, 97, 100, 12);
+        var service = harness.Service;
+
+        service.Register("gm-open-low", "Password123", "GM");
+        var session = ServiceTestSupport.GetValue(service.Login("gm-open-low", "Password123")).SessionToken;
+        var campaign = ServiceTestSupport.GetValue(service.CreateCampaign(session, "Rolemaster", "rolemaster"));
+        var character = ServiceTestSupport.GetValue(service.CreateCharacter(session, "Hero", campaign.Id));
+        var skill = ServiceTestSupport.GetValue(service.CreateSkill(session, character.Id, "Awareness", "d100!+85", 0, false, null, 5));
+
+        var roll = ServiceTestSupport.GetValue(service.RollSkill(session, skill.Id, "public"));
+        var logPage = ServiceTestSupport.GetValue(service.GetCampaignLogPage(session, campaign.Id, limit: 5));
+
+        Assert.Equal(-119, roll.Result);
+        Assert.Equal("5-(97+100+12)+85=-119", roll.Breakdown);
+        Assert.Equal("5 - (97 + 100 + 12) | open-ended low", Assert.Single(logPage.Entries).SummaryText);
+        Assert.Collection(
+            roll.Dice,
+            die =>
+            {
+                Assert.Equal(5, die.Roll);
+                Assert.Equal(1, die.Sequence);
+                Assert.Equal(RollDieKinds.RolemasterOpenEndedInitial, die.Kind);
+                Assert.Equal(5, die.SignedContribution);
+            },
+            die =>
+            {
+                Assert.Equal(97, die.Roll);
+                Assert.Equal(2, die.Sequence);
+                Assert.Equal(RollDieKinds.RolemasterOpenEndedLowSubtract, die.Kind);
+                Assert.Equal(-97, die.SignedContribution);
+            },
+            die =>
+            {
+                Assert.Equal(100, die.Roll);
+                Assert.Equal(3, die.Sequence);
+                Assert.Equal(RollDieKinds.RolemasterOpenEndedLowSubtract, die.Kind);
+                Assert.Equal(-100, die.SignedContribution);
+            },
+            die =>
+            {
+                Assert.Equal(12, die.Roll);
+                Assert.Equal(4, die.Sequence);
+                Assert.Equal(RollDieKinds.RolemasterOpenEndedLowSubtract, die.Kind);
+                Assert.Equal(-12, die.SignedContribution);
+            });
+    }
+}

RpgRoller/Components/Pages/HomeControls/RollDiceStrip.razor

@@ -3,7 +3,7 @@
     <div class="roll-dice-strip" aria-label="@AriaLabel">
         @foreach (var die in Dice)
         {
-            <span class="@RollDieCssClass(die)" title="@RollDieTitle(die)">@RollDieGlyph(die.Roll)</span>
+            <span class="@RollDieCssClass(die)" title="@RollDieTitle(die)">@RollDieDisplay(die)</span>
         }
     </div>
 }

RpgRoller/Components/Pages/HomeControls/RollDiceStrip.razor.cs

@@ -21,6 +21,16 @@ public partial class RollDiceStrip
         };
     }
 
+    private static string RollDieDisplay(RollDieResult die)
+    {
+        return die.Kind switch
+        {
+            RollDieKinds.RolemasterOpenEndedHigh        => $"+{die.Roll}",
+            RollDieKinds.RolemasterOpenEndedLowSubtract => $"-{die.Roll}",
+            _                                           => RollDieGlyph(die.Roll)
+        };
+    }
+
     private static string RollDieCssClass(RollDieResult die)
     {
         var classes = new List<string> { "die-chip" };
@@ -39,12 +49,34 @@ public partial class RollDiceStrip
         if (die.Added)
             classes.Add("added");
 
+        switch (die.Kind)
+        {
+            case RollDieKinds.RolemasterInitiative:
+                classes.Add("rolemaster-initiative");
+                break;
+            case RollDieKinds.RolemasterPercentile:
+                classes.Add("rolemaster-percentile");
+                break;
+            case RollDieKinds.RolemasterOpenEndedInitial:
+                classes.Add("rolemaster-open-ended-initial");
+                break;
+            case RollDieKinds.RolemasterOpenEndedHigh:
+                classes.Add("rolemaster-open-ended-high");
+                break;
+            case RollDieKinds.RolemasterOpenEndedLowSubtract:
+                classes.Add("rolemaster-open-ended-low-subtract");
+                break;
+        }
+
         return string.Join(" ", classes);
     }
 
     private static string RollDieTitle(RollDieResult die)
     {
         var labels = new List<string> { $"Roll {die.Roll}" };
+        if (die.Sequence.HasValue)
+            labels.Add($"step {die.Sequence.Value}");
+
         if (die.Wild)
             labels.Add("wild");
 
@@ -60,6 +92,25 @@ public partial class RollDiceStrip
         if (die.Added)
             labels.Add("added");
 
+        switch (die.Kind)
+        {
+            case RollDieKinds.RolemasterInitiative:
+                labels.Add("Rolemaster initiative");
+                break;
+            case RollDieKinds.RolemasterPercentile:
+                labels.Add("Rolemaster percentile");
+                break;
+            case RollDieKinds.RolemasterOpenEndedInitial:
+                labels.Add("Rolemaster open-ended initial");
+                break;
+            case RollDieKinds.RolemasterOpenEndedHigh:
+                labels.Add($"Rolemaster high follow-up (+{die.Roll})");
+                break;
+            case RollDieKinds.RolemasterOpenEndedLowSubtract:
+                labels.Add($"Rolemaster low-end subtraction (-{die.Roll})");
+                break;
+        }
+
         return string.Join(", ", labels);
     }
 

RpgRoller/Contracts/ApiContracts.cs

@@ -1,3 +1,5 @@
+using System.Text.Json.Serialization;
+
 namespace RpgRoller.Contracts;
 
 public sealed record HealthResponse(string Status);
@@ -48,7 +50,50 @@ public sealed record SkillSummary(Guid Id, Guid CharacterId, Guid? SkillGroupId,
 
 public sealed record RollSkillRequest(string Visibility);
 
-public sealed record RollDieResult(int Roll, bool Crit, bool Fumble, bool Wild, bool Removed, bool Added);
+public static class RollDieKinds
+{
+    public const string RolemasterInitiative = "rolemaster-initiative";
+    public const string RolemasterPercentile = "rolemaster-percentile";
+    public const string RolemasterOpenEndedInitial = "rolemaster-open-ended-initial";
+    public const string RolemasterOpenEndedHigh = "rolemaster-open-ended-high";
+    public const string RolemasterOpenEndedLowSubtract = "rolemaster-open-ended-low-subtract";
+}
+
+public sealed record RollDieResult
+{
+    public RollDieResult()
+    {
+    }
+
+    public RollDieResult(int roll, bool crit, bool fumble, bool wild, bool removed, bool added, int? sequence = null, string? kind = null, int? signedContribution = null)
+    {
+        Roll = roll;
+        Crit = crit;
+        Fumble = fumble;
+        Wild = wild;
+        Removed = removed;
+        Added = added;
+        Sequence = sequence;
+        Kind = kind;
+        SignedContribution = signedContribution;
+    }
+
+    public int Roll { get; init; }
+    public bool Crit { get; init; }
+    public bool Fumble { get; init; }
+    public bool Wild { get; init; }
+    public bool Removed { get; init; }
+    public bool Added { get; init; }
+
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public int? Sequence { get; init; }
+
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public string? Kind { get; init; }
+
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public int? SignedContribution { get; init; }
+}
 
 public sealed record RollResult(Guid RollId, Guid CampaignId, Guid CharacterId, Guid SkillId, Guid RollerUserId, string Visibility, int Result, string Breakdown, IReadOnlyList<RollDieResult> Dice, DateTimeOffset TimestampUtc);
 

RpgRoller/Services/GameService.cs

@@ -942,7 +942,21 @@ public sealed class GameService : IGameService
 
     private (int Total, string Breakdown, IReadOnlyList<RollDieResult> Dice) ComputeRoll(RulesetKind ruleset, DiceExpression expression, Skill skill)
     {
-        return ruleset == RulesetKind.D6 ? ComputeD6Roll(expression, skill.WildDice, skill.AllowFumble) : ComputeStandardRoll(expression);
+        if (ruleset == RulesetKind.D6)
+            return ComputeD6Roll(expression, skill.WildDice, skill.AllowFumble);
+
+        if (ruleset == RulesetKind.Rolemaster)
+        {
+            return expression.Kind switch
+            {
+                DiceExpressionKind.RolemasterInitiative          => ComputeRolemasterInitiativeRoll(expression),
+                DiceExpressionKind.RolemasterPercentile          => ComputeRolemasterPercentileRoll(expression),
+                DiceExpressionKind.RolemasterOpenEndedPercentile => ComputeRolemasterOpenEndedRoll(expression, skill.FumbleRange.GetValueOrDefault()),
+                _                                               => ComputeStandardRoll(expression)
+            };
+        }
+
+        return ComputeStandardRoll(expression);
     }
 
     private (int Total, string Breakdown, IReadOnlyList<RollDieResult> Dice) ComputeStandardRoll(DiceExpression expression)
@@ -961,6 +975,62 @@ public sealed class GameService : IGameService
         return (total, BuildBreakdown(diceValues, expression.Modifier, total), dice);
     }
 
+    private (int Total, string Breakdown, IReadOnlyList<RollDieResult> Dice) ComputeRolemasterInitiativeRoll(DiceExpression expression)
+    {
+        var diceValues = new int[expression.DiceCount];
+        var dice = new RollDieResult[expression.DiceCount];
+        var total = expression.Modifier;
+        for (var i = 0; i < expression.DiceCount; i += 1)
+        {
+            var value = m_DiceRoller.Roll(expression.Sides);
+            diceValues[i] = value;
+            dice[i] = CreateRolemasterDie(value, i + 1, RollDieKinds.RolemasterInitiative, value);
+            total += value;
+        }
+
+        return (total, BuildBreakdown(diceValues, expression.Modifier, total), dice);
+    }
+
+    private (int Total, string Breakdown, IReadOnlyList<RollDieResult> Dice) ComputeRolemasterPercentileRoll(DiceExpression expression)
+    {
+        var roll = m_DiceRoller.Roll(expression.Sides);
+        var total = roll + expression.Modifier;
+        var dice = new[]
+        {
+            CreateRolemasterDie(roll, 1, RollDieKinds.RolemasterPercentile, roll)
+        };
+
+        return (total, BuildBreakdown([roll], expression.Modifier, total), dice);
+    }
+
+    private (int Total, string Breakdown, IReadOnlyList<RollDieResult> Dice) ComputeRolemasterOpenEndedRoll(DiceExpression expression, int fumbleRange)
+    {
+        var initialRoll = m_DiceRoller.Roll(expression.Sides);
+        var followUpRolls = new List<int>();
+        var dice = new List<RollDieResult>
+        {
+            CreateRolemasterDie(initialRoll, 1, RollDieKinds.RolemasterOpenEndedInitial, initialRoll)
+        };
+
+        var baseTotal = initialRoll;
+        var subtractFollowUps = false;
+        if (initialRoll >= 96)
+        {
+            followUpRolls.AddRange(RollRolemasterHighOpenEndedChain(dice, sequenceStart: 2, subtract: false));
+            baseTotal += followUpRolls.Sum();
+        }
+        else if (initialRoll <= fumbleRange)
+        {
+            subtractFollowUps = true;
+            followUpRolls.AddRange(RollRolemasterHighOpenEndedChain(dice, sequenceStart: 2, subtract: true));
+            baseTotal -= followUpRolls.Sum();
+        }
+
+        var total = baseTotal + expression.Modifier;
+        var breakdown = BuildRolemasterOpenEndedBreakdown(initialRoll, followUpRolls, subtractFollowUps, expression.Modifier, total);
+        return (total, breakdown, dice);
+    }
+
     private (int Total, string Breakdown, IReadOnlyList<RollDieResult> Dice) ComputeD6Roll(DiceExpression expression, int wildDice, bool allowFumble)
     {
         var initialDice = expression.DiceCount;
@@ -1041,14 +1111,63 @@ public sealed class GameService : IGameService
         return (total, BuildBreakdown(includedDice, expression.Modifier, total), dieResults);
     }
 
+    private IEnumerable<int> RollRolemasterHighOpenEndedChain(List<RollDieResult> dice, int sequenceStart, bool subtract)
+    {
+        var followUpRolls = new List<int>();
+        var sequence = sequenceStart;
+
+        while (true)
+        {
+            var roll = m_DiceRoller.Roll(100);
+            followUpRolls.Add(roll);
+            dice.Add(CreateRolemasterDie(
+                roll,
+                sequence,
+                subtract ? RollDieKinds.RolemasterOpenEndedLowSubtract : RollDieKinds.RolemasterOpenEndedHigh,
+                subtract ? -roll : roll));
+
+            sequence += 1;
+            if (roll < 96)
+                break;
+        }
+
+        return followUpRolls;
+    }
+
+    private static RollDieResult CreateRolemasterDie(int roll, int sequence, string kind, int signedContribution)
+    {
+        return new(roll, false, false, false, false, kind == RollDieKinds.RolemasterOpenEndedHigh, sequence, kind, signedContribution);
+    }
+
     private static string BuildBreakdown(IEnumerable<int> diceValues, int modifier, int total)
     {
         var dicePart = string.Join("+", diceValues);
         if (string.IsNullOrWhiteSpace(dicePart))
             dicePart = "0";
 
-        var modifierPart = modifier > 0 ? $"+{modifier}" : string.Empty;
+        return BuildModifierBreakdown(dicePart, modifier, total);
-        return $"{dicePart}{modifierPart}={total}";
+    }
+
+    private static string BuildRolemasterOpenEndedBreakdown(int initialRoll, IReadOnlyList<int> followUpRolls, bool subtractFollowUps, int modifier, int total)
+    {
+        var core = initialRoll.ToString();
+        if (followUpRolls.Count > 0)
+        {
+            var followUpBreakdown = string.Join("+", followUpRolls);
+            core = subtractFollowUps ? $"{core}-({followUpBreakdown})" : $"{core}+{followUpBreakdown}";
+        }
+
+        return BuildModifierBreakdown(core, modifier, total);
+    }
+
+    private static string BuildModifierBreakdown(string core, int modifier, int total)
+    {
+        return modifier switch
+        {
+            > 0 => $"{core}+{modifier}={total}",
+            < 0 => $"{core}{modifier}={total}",
+            _   => $"{core}={total}"
+        };
     }
 
     private ServiceResult<Guid?> ResolveSkillGroupForSkillChangeLocked(Guid? requestedSkillGroupId, Guid characterId)
@@ -1248,6 +1367,9 @@ public sealed class GameService : IGameService
         if (dice.Count == 0)
             return "No detail available.";
 
+        if (dice.Any(die => IsRolemasterDieKind(die.Kind)))
+            return BuildRolemasterCompactLogSummary(dice);
+
         var preview = string.Join(", ", dice.Take(3).Select(die => die.Roll.ToString()));
         if (dice.Count > 3)
             preview = $"{preview}, ...";
@@ -1265,6 +1387,46 @@ public sealed class GameService : IGameService
         return tags.Count == 0 ? preview : $"{preview} | {string.Join(", ", tags)}";
     }
 
+    private static string BuildRolemasterCompactLogSummary(IReadOnlyList<RollDieResult> dice)
+    {
+        var openEndedInitial = dice.FirstOrDefault(die => string.Equals(die.Kind, RollDieKinds.RolemasterOpenEndedInitial, StringComparison.Ordinal));
+        if (openEndedInitial is not null)
+        {
+            var highFollowUps = dice
+                .Where(die => string.Equals(die.Kind, RollDieKinds.RolemasterOpenEndedHigh, StringComparison.Ordinal))
+                .Select(die => die.Roll.ToString())
+                .ToArray();
+            if (highFollowUps.Length > 0)
+                return $"{openEndedInitial.Roll} + {string.Join(" + ", highFollowUps)} | open-ended high";
+
+            var lowFollowUps = dice
+                .Where(die => string.Equals(die.Kind, RollDieKinds.RolemasterOpenEndedLowSubtract, StringComparison.Ordinal))
+                .Select(die => die.Roll.ToString())
+                .ToArray();
+            if (lowFollowUps.Length > 0)
+                return $"{openEndedInitial.Roll} - ({string.Join(" + ", lowFollowUps)}) | open-ended low";
+
+            return $"{openEndedInitial.Roll} | open-ended";
+        }
+
+        if (dice.Any(die => string.Equals(die.Kind, RollDieKinds.RolemasterInitiative, StringComparison.Ordinal)))
+            return $"{string.Join(" + ", dice.Select(die => die.Roll.ToString()))} | initiative";
+
+        if (dice.Any(die => string.Equals(die.Kind, RollDieKinds.RolemasterPercentile, StringComparison.Ordinal)))
+            return $"{dice[0].Roll} | percentile";
+
+        return string.Join(", ", dice.Take(3).Select(die => die.Roll.ToString()));
+    }
+
+    private static bool IsRolemasterDieKind(string? kind)
+    {
+        return kind is RollDieKinds.RolemasterInitiative or
+            RollDieKinds.RolemasterPercentile or
+            RollDieKinds.RolemasterOpenEndedInitial or
+            RollDieKinds.RolemasterOpenEndedHigh or
+            RollDieKinds.RolemasterOpenEndedLowSubtract;
+    }
+
     private bool CanViewRollLocked(UserAccount user, Campaign campaign, RollLogEntry entry)
     {
         return CanViewCampaignLocked(user.Id, campaign.Id) &&

RpgRoller/wwwroot/styles.css

@@ -528,15 +528,16 @@ select:focus-visible {
     display: inline-flex;
     align-items: center;
     justify-content: center;
-    width: 2.1rem;
+    min-width: 2.1rem;
     height: 2.1rem;
-    padding-top: 4px;
+    padding: 0.2rem 0.45rem 0;
     border: 2px solid #2a2418;
     border-radius: 0.45rem;
     background: #ffffff;
     color: #1f1a13;
     font-size: 2rem;
     line-height: 1;
+    font-variant-numeric: tabular-nums;
 }
 
 .die-chip.wild {
@@ -565,6 +566,36 @@ select:focus-visible {
     border-style: dashed;
 }
 
+.die-chip.rolemaster-initiative,
+.die-chip.rolemaster-percentile,
+.die-chip.rolemaster-open-ended-initial,
+.die-chip.rolemaster-open-ended-high,
+.die-chip.rolemaster-open-ended-low-subtract {
+    padding-top: 0;
+    font-size: 1rem;
+    font-weight: 700;
+    line-height: 1.1;
+}
+
+.die-chip.rolemaster-initiative,
+.die-chip.rolemaster-percentile,
+.die-chip.rolemaster-open-ended-initial {
+    background: #f8f1df;
+    color: #3f2f12;
+}
+
+.die-chip.rolemaster-open-ended-high {
+    background: #dff6df;
+    color: #1d5b26;
+    border-color: #2a7c39;
+}
+
+.die-chip.rolemaster-open-ended-low-subtract {
+    background: #ffe1dc;
+    color: #8a2217;
+    border-color: #b74334;
+}
+
 .empty,
 .muted {
     color: var(--muted);

openapi/RpgRoller.json

@@ -1029,6 +1029,20 @@
           },
           "added": {
             "type": "boolean"
+          },
+          "sequence": {
+            "type": "integer",
+            "format": "int32",
+            "nullable": true
+          },
+          "kind": {
+            "type": "string",
+            "nullable": true
+          },
+          "signedContribution": {
+            "type": "integer",
+            "format": "int32",
+            "nullable": true
           }
         },
         "required": [

tests/e2e/smoke.spec.js

@@ -1,5 +1,11 @@
 const { test, expect } = require("@playwright/test");
 
+async function postJson(request, url, data) {
+  const response = await request.post(url, { data });
+  expect(response.ok()).toBeTruthy();
+  return await response.json();
+}
+
 test("home page loads auth entry points", async ({ page }) => {
   await page.goto("/");
 
@@ -9,3 +15,51 @@ test("home page loads auth entry points", async ({ page }) => {
   await expect(page.getByLabel("Username").first()).toBeVisible();
   await expect(page.getByLabel("Password").nth(1)).toBeVisible();
 });
+
+test("Rolemaster open-ended roll detail renders specialized dice chips", async ({ page, context }) => {
+  const username = `rm-${Date.now()}`;
+  const displayName = "Rolemaster Smoke";
+
+  await postJson(context.request, "/api/auth/register", {
+    username,
+    password: "Password123",
+    displayName
+  });
+
+  const loginResponse = await context.request.post("/api/auth/login", {
+    data: {
+      username,
+      password: "Password123"
+    }
+  });
+  expect(loginResponse.ok()).toBeTruthy();
+
+  const campaign = await postJson(context.request, "/api/campaigns", {
+    name: "Rolemaster Smoke",
+    rulesetId: "rolemaster"
+  });
+  const character = await postJson(context.request, "/api/characters", {
+    name: "Open Ender",
+    campaignId: campaign.id
+  });
+  const skill = await postJson(context.request, `/api/characters/${character.id}/skills`, {
+    name: "Open Sight",
+    diceRollDefinition: "d100!+85",
+    wildDice: 0,
+    allowFumble: false,
+    fumbleRange: 95
+  });
+
+  await postJson(context.request, `/api/skills/${skill.id}/roll`, { visibility: "public" });
+
+  await page.goto("/");
+  await expect(page.getByText("Campaign Log")).toBeVisible();
+
+  const logEntry = page.locator(".log-panel .log-entry-toggle").first();
+  await expect(logEntry).toBeVisible();
+  await logEntry.click();
+
+  const rolemasterFollowUpDice = page.locator(".die-chip.rolemaster-open-ended-high, .die-chip.rolemaster-open-ended-low-subtract");
+  await expect(rolemasterFollowUpDice.first()).toBeVisible();
+  await expect(page.locator(".log-detail .roll-dice-strip")).toBeVisible();
+});