feat(arena-colosseum): playable bracket + rank-match promotion (phase 2)

Closes 4 more arena-colosseum spec shapes (6/16 → 10/16): the dual-prefix
battle URLs (colosseum_battle/* and colosseum_rank_battle/*) for both
do_matching and per-match finish, plus the bracket-end /finish + /retire
pair on /arena_colosseum.

* ColosseumProgressionService: pure-logic decisions for win-threshold
  advancement, 3008 promotion trigger, and per-round reward bundles.
  Extends ColosseumRoundsConfig with FinishRewards/RetireRewards per
  round + a top-level ChampionRewards list.
* MatchContextBuilder.BuildForColosseumAsync: lifts the registered deck
  via IDeckRepository (NOT viewer-graph) per project_ef_nav_include_pitfall.
* ArenaColosseumBattleController: dual route prefixes off one controller
  via explicit absolute [HttpPost("/...")] routes — does NOT extend
  SVSimController's [Route("[controller]")]. Same pattern as FreeBattle.
  URL-vs-IsRankMatching mismatch returns 400 with a phase-mismatch error;
  no-deck triggers the standard 3001 matchmaking-illegal state. 3008
  flips run.IsRankMatching exactly once via the progression service.
* /arena_colosseum/finish + /retire share FinishResponse (rewards +
  reward_list + colosseum_status). Champion finish appends ChampionRewards
  and surfaces colosseum_status.is_champion = true. Both delete the run
  row after granting via IInventoryTransaction.GrantAsync.
* DI: ModePolicy entries for "colosseum_battle" and "colosseum_rank_battle".
* Tests: 8 progression-service unit tests (pure logic), 5 battle-controller
  HTTP tests, 5 bracket-terminate HTTP tests, 2 full-bracket E2E walks
  (champion path + retire mid-round). Full suite: 1331/1331.

SVSim.EmulatedEntrypoint/Controllers/ArenaColosseumBattleController.cs

@@ -0,0 +1,175 @@
+using System.Text.Json;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using SVSim.BattleNode.Bridge;
+using SVSim.Database.Repositories.Viewer;
+using SVSim.EmulatedEntrypoint.Constants;
+using SVSim.EmulatedEntrypoint.Matching;
+using SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
+using SVSim.EmulatedEntrypoint.Security;
+using SVSim.EmulatedEntrypoint.Security.SteamSessionAuthentication;
+using SVSim.EmulatedEntrypoint.Services;
+using SVSim.EmulatedEntrypoint.Services.ArenaColosseum;
+
+namespace SVSim.EmulatedEntrypoint.Controllers;
+
+/// <summary>
+/// Per-match URLs for the Colosseum bracket — the dual <c>colosseum_battle/*</c> +
+/// <c>colosseum_rank_battle/*</c> route family. Does NOT extend <see cref="SVSimController"/>'s
+/// <c>[Route("[controller]")]</c> because we need explicit absolute routes for two prefixes
+/// off one controller (same pattern as <see cref="FreeBattleController"/>).
+/// <para>
+/// The URL is the bracket-phase signal per do-matching.md §"server-side bidirectional
+/// mapping"; <see cref="ViewerArenaColosseumRun.IsRankMatching"/> flips to true once the
+/// node has signalled <c>matching_state == 3008</c> on a prior <c>do_matching</c>.
+/// </para>
+/// </summary>
+[ApiController]
+[Authorize(AuthenticationSchemes = SteamAuthenticationConstants.SchemeName)]
+public sealed class ArenaColosseumBattleController : ControllerBase
+{
+    /// <summary>Per FinishTaskBase.IsEffectiveErrorCode — code 3502 ("battle already finished")
+    /// is tolerated as a non-error retry, parsed the same as 1.</summary>
+    private const int BattleAlreadyFinishedResultCode = 3502;
+
+    private readonly IMatchContextBuilder _ctxBuilder;
+    private readonly IMatchingResolver _resolver;
+    private readonly IArenaColosseumRunRepository _runs;
+    private readonly IColosseumProgressionService _progression;
+    private readonly ILogger<ArenaColosseumBattleController> _log;
+
+    public ArenaColosseumBattleController(
+        IMatchContextBuilder ctxBuilder,
+        IMatchingResolver resolver,
+        IArenaColosseumRunRepository runs,
+        IColosseumProgressionService progression,
+        ILogger<ArenaColosseumBattleController> log)
+    {
+        _ctxBuilder = ctxBuilder;
+        _resolver = resolver;
+        _runs = runs;
+        _progression = progression;
+        _log = log;
+    }
+
+    private bool TryGetViewerId(out long viewerId)
+    {
+        viewerId = 0;
+        var claim = User.Claims.FirstOrDefault(c => c.Type == ShadowverseClaimTypes.ViewerIdClaim)?.Value;
+        return claim is not null && long.TryParse(claim, out viewerId);
+    }
+
+    [HttpPost("/colosseum_battle/do_matching")]
+    public Task<IActionResult> DoMatchingPreRank(
+        [FromBody] ColosseumDoMatchingRequestDto req, CancellationToken ct)
+        => DoMatchingInternal(isRankUrl: false, req, ct);
+
+    [HttpPost("/colosseum_rank_battle/do_matching")]
+    public Task<IActionResult> DoMatchingPostRank(
+        [FromBody] ColosseumDoMatchingRequestDto req, CancellationToken ct)
+        => DoMatchingInternal(isRankUrl: true, req, ct);
+
+    [HttpPost("/colosseum_battle/finish")]
+    public Task<IActionResult> FinishPreRank(
+        [FromBody] ColosseumBattleFinishRequestDto req, CancellationToken ct)
+        => FinishInternal(isRankUrl: false, req, ct);
+
+    [HttpPost("/colosseum_rank_battle/finish")]
+    public Task<IActionResult> FinishPostRank(
+        [FromBody] ColosseumBattleFinishRequestDto req, CancellationToken ct)
+        => FinishInternal(isRankUrl: true, req, ct);
+
+    private async Task<IActionResult> DoMatchingInternal(
+        bool isRankUrl, ColosseumDoMatchingRequestDto req, CancellationToken ct)
+    {
+        if (!TryGetViewerId(out var vid)) return Unauthorized();
+
+        var run = await _runs.GetByViewerIdAsync(vid);
+        if (run is null)
+        {
+            return BadRequest(new { error = "arena_colosseum_no_active_run" });
+        }
+        if (isRankUrl != run.IsRankMatching)
+        {
+            return BadRequest(new
+            {
+                error = "colosseum_url_phase_mismatch",
+                is_rank_matching = run.IsRankMatching,
+                requested_rank_url = isRankUrl,
+            });
+        }
+
+        MatchContext ctx;
+        try
+        {
+            ctx = await _ctxBuilder.BuildForColosseumAsync(vid);
+        }
+        catch (InvalidOperationException ex)
+        {
+            _log.LogWarning(ex,
+                "Colosseum BuildForColosseumAsync failed for viewer {Vid}; returning 3001.", vid);
+            return Ok(new Models.Dtos.FreeBattle.DoMatchingResponseDto
+            {
+                MatchingState = 3001,
+                NodeServerUrl = "",
+            });
+        }
+
+        var mode = isRankUrl ? "colosseum_rank_battle" : "colosseum_battle";
+        var resolution = await _resolver.ResolveAsync(mode, new BattlePlayer(vid, ctx), ct);
+
+        // Promotion: server flips IsRankMatching once on the 3008 signal. Subsequent battle
+        // URLs must use the rank prefix. (Plan §"matching_state == 3008 is the promotion trigger".)
+        if (_progression.ShouldPromoteToRankMatching(run, resolution.MatchingState))
+        {
+            run.IsRankMatching = true;
+            await _runs.UpsertAsync(run);
+        }
+
+        return Ok(new Models.Dtos.FreeBattle.DoMatchingResponseDto
+        {
+            MatchingState = resolution.MatchingState,
+            BattleId = resolution.BattleId,
+            NodeServerUrl = resolution.NodeServerUrl,
+        });
+    }
+
+    private async Task<IActionResult> FinishInternal(
+        bool isRankUrl, ColosseumBattleFinishRequestDto req, CancellationToken ct)
+    {
+        if (!TryGetViewerId(out var vid)) return Unauthorized();
+
+        var run = await _runs.GetByViewerIdAsync(vid);
+        if (run is null)
+        {
+            return BadRequest(new { error = "arena_colosseum_no_active_run" });
+        }
+
+        // Match-result tracking: 1 = win, 2 = loss, 0 = draw/abort. Record_list mirrors
+        // ColosseumTopTask.battle_results.result_list (1=win, 0=loss). is_retire surfaces
+        // as a non-counted result — does not advance the bracket.
+        bool counts = req.IsRetire == 0;
+        if (counts)
+        {
+            bool isWin = req.BattleResult == 1;
+            run.BattleCountThisRound += 1;
+            if (isWin) run.WinCount += 1;
+            else run.LossCount += 1;
+
+            var resultList = ParseIntList(run.ResultListJson);
+            resultList.Add(isWin ? 1 : 0);
+            run.ResultListJson = JsonSerializer.Serialize(resultList);
+            await _runs.UpsertAsync(run);
+        }
+
+        // result_code 3502 ("battle already finished") is the idempotent-retry tolerance per
+        // FinishTaskBase.IsEffectiveErrorCode. Server emits standard data; the translation
+        // middleware sets the wire result_code via data_headers from the response envelope.
+        return Ok(new ColosseumBattleFinishResponseDto { BattleResult = req.BattleResult });
+    }
+
+    private static List<int> ParseIntList(string json) =>
+        string.IsNullOrEmpty(json)
+            ? new()
+            : JsonSerializer.Deserialize<List<int>>(json) ?? new();
+}

SVSim.EmulatedEntrypoint/Controllers/ArenaColosseumController.cs

@@ -12,6 +12,7 @@ using SVSim.EmulatedEntrypoint.Models.Dtos.Common.ArenaTwoPick;
 using SVSim.EmulatedEntrypoint.Models.Dtos.Requests;
 using SVSim.EmulatedEntrypoint.Models.Dtos.Requests.ArenaColosseum;
 using SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaColosseum;
+using SVSim.EmulatedEntrypoint.Services.ArenaColosseum;
 
 namespace SVSim.EmulatedEntrypoint.Controllers;
 
@@ -28,17 +29,20 @@ public class ArenaColosseumController : SVSimController
     private readonly IArenaColosseumRunRepository _runs;
     private readonly IInventoryService _inventory;
     private readonly IDeckRepository _decks;
+    private readonly IColosseumProgressionService _progression;
 
     public ArenaColosseumController(
         IGameConfigService config,
         IArenaColosseumRunRepository runs,
         IInventoryService inventory,
-        IDeckRepository decks)
+        IDeckRepository decks,
+        IColosseumProgressionService progression)
     {
         _config = config;
         _runs = runs;
         _inventory = inventory;
         _decks = decks;
+        _progression = progression;
     }
 
     [HttpPost("top")]
@@ -247,6 +251,104 @@ public class ArenaColosseumController : SVSimController
         return Ok(new { });
     }
 
+    [HttpPost("finish")]
+    public async Task<IActionResult> Finish([FromBody] BaseRequest _)
+    {
+        if (!TryGetViewerId(out var vid)) return Unauthorized();
+        var run = await _runs.GetByViewerIdAsync(vid);
+        if (run is null) return BadRequest(new { error = "no_active_run" });
+
+        var rounds = _config.Get<ColosseumRoundsConfig>();
+        var decision = _progression.DecideAdvancement(run, rounds);
+        if (!decision.IsBracketEnd)
+        {
+            return BadRequest(new { error = "bracket_not_finished" });
+        }
+
+        run.IsChampion = decision.IsChampion;
+        var rewardEntries = _progression.BuildFinishRewards(run, rounds);
+        var (wireRewards, wireRewardList) = await GrantRewardsAsync(vid, rewardEntries);
+
+        await _runs.DeleteAsync(vid);
+
+        return Ok(new FinishResponse
+        {
+            Rewards = wireRewards,
+            RewardList = wireRewardList,
+            ColosseumStatus = new ColosseumOwnStatus
+            {
+                NowRoundId = run.RoundId,
+                IsChampion = decision.IsChampion ? true : null,
+                ColosseumName = decision.IsChampion ? rounds.Rounds.Count > 0
+                    ? _config.Get<ColosseumSeasonConfig>().ColosseumName
+                    : null : null,
+            },
+        });
+    }
+
+    [HttpPost("retire")]
+    public async Task<IActionResult> Retire([FromBody] BaseRequest _)
+    {
+        if (!TryGetViewerId(out var vid)) return Unauthorized();
+        var run = await _runs.GetByViewerIdAsync(vid);
+        if (run is null) return BadRequest(new { error = "no_active_run" });
+
+        var rounds = _config.Get<ColosseumRoundsConfig>();
+        var rewardEntries = _progression.BuildRetireRewards(run, rounds);
+        var (wireRewards, wireRewardList) = await GrantRewardsAsync(vid, rewardEntries);
+
+        await _runs.DeleteAsync(vid);
+
+        return Ok(new FinishResponse
+        {
+            Rewards = wireRewards,
+            RewardList = wireRewardList,
+            ColosseumStatus = new ColosseumOwnStatus
+            {
+                NowRoundId = run.RoundId,
+                RestEntryNum = 0,
+            },
+        });
+    }
+
+    /// <summary>
+    /// Grant the bundle through <c>IInventoryTransaction.GrantAsync</c> per
+    /// <c>feedback_reward_grant_service</c> — single dispatch table for every UserGoodsType.
+    /// Returns the two wire forms (rich <c>rewards</c> receipt + wallet-delta <c>reward_list</c>).
+    /// </summary>
+    private async Task<(List<ColosseumReceivedReward>, List<RewardEntryDto>)> GrantRewardsAsync(
+        long viewerId, IReadOnlyList<ColosseumRoundsConfig.RewardEntry> bundle)
+    {
+        var receipts = new List<ColosseumReceivedReward>();
+        var deltas = new List<RewardEntryDto>();
+        if (bundle.Count == 0) return (receipts, deltas);
+
+        await using var tx = await _inventory.BeginAsync(viewerId);
+        foreach (var entry in bundle)
+        {
+            var granted = await tx.GrantAsync(entry.Type, entry.DetailId, entry.Count);
+            receipts.Add(new ColosseumReceivedReward
+            {
+                RewardNumber = entry.Count,
+                RewardType = (int)entry.Type,
+                RewardDetailId = entry.DetailId,
+                Name = entry.Name,
+            });
+            // GrantAsync returns one or more (RewardType, RewardId, RewardNum) tuples — the
+            // post-state-total semantics are owned by the inventory commit, which the wallet-delta
+            // reflection inherits via tx.CommitAsync below.
+            var first = granted.FirstOrDefault();
+            deltas.Add(new RewardEntryDto
+            {
+                RewardType = first is null ? (int)entry.Type : (int)first.RewardType,
+                RewardId = first?.RewardId ?? entry.DetailId,
+                RewardNum = first?.RewardNum ?? entry.Count,
+            });
+        }
+        await tx.CommitAsync();
+        return (receipts, deltas);
+    }
+
     private static int ResolveServerRoundId(ColosseumSeasonConfig season) => 1;
 
     private async Task<RewardEntryDto> DebitCrystalAsync(IInventoryTransaction tx, int cost)

SVSim.EmulatedEntrypoint/Models/Dtos/ArenaColosseum/BattleDoMatchingRequestDto.cs

@@ -0,0 +1,33 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Requests;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
+
+/// <summary>
+/// <c>POST /colosseum_battle/do_matching</c> + <c>POST /colosseum_rank_battle/do_matching</c>.
+/// Standard <c>DoMatchingParam</c> wire shape — same fields as rank/free-battle's variant.
+/// Per do-matching.md, post-promotion the client forces <c>need_init = 0</c>, but the
+/// server tolerates either value (URL is the routing signal).
+/// </summary>
+[MessagePackObject]
+public sealed class ColosseumDoMatchingRequestDto : BaseRequest
+{
+    [JsonPropertyName("need_init")] [Key("need_init")]
+    public int NeedInit { get; set; }
+
+    [JsonPropertyName("card_master_hash")] [Key("card_master_hash")]
+    public string? CardMasterHash { get; set; }
+
+    [JsonPropertyName("log")] [Key("log")]
+    public int Log { get; set; }
+
+    [JsonPropertyName("use_stage_select")] [Key("use_stage_select")]
+    public int UseStageSelect { get; set; }
+
+    [JsonPropertyName("excluded_field_id_list")] [Key("excluded_field_id_list")]
+    public List<long> ExcludedFieldIdList { get; set; } = new();
+
+    [JsonPropertyName("is_default_skin")] [Key("is_default_skin")]
+    public int IsDefaultSkin { get; set; }
+}

SVSim.EmulatedEntrypoint/Models/Dtos/ArenaColosseum/BattleFinishRequestDto.cs

@@ -0,0 +1,49 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Requests;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
+
+/// <summary>
+/// <c>POST /colosseum_battle/finish</c> + <c>POST /colosseum_rank_battle/finish</c> request
+/// body — the per-match finish, NOT the bracket-end <c>/arena_colosseum/finish</c>.
+/// Standard <c>BattleFinishParam</c> shape inherited from <c>FinishTaskBase</c>.
+/// </summary>
+[MessagePackObject]
+public sealed class ColosseumBattleFinishRequestDto : BaseRequest
+{
+    [JsonPropertyName("battle_result")] [Key("battle_result")]
+    public int BattleResult { get; set; }
+
+    [JsonPropertyName("is_retire")] [Key("is_retire")]
+    public int IsRetire { get; set; }
+
+    [JsonPropertyName("recovery_data")] [Key("recovery_data")]
+    public string? RecoveryData { get; set; }
+
+    [JsonPropertyName("class_id")] [Key("class_id")]
+    public int ClassId { get; set; }
+
+    [JsonPropertyName("total_turn")] [Key("total_turn")]
+    public int TotalTurn { get; set; }
+
+    [JsonPropertyName("evolve_count")] [Key("evolve_count")]
+    public int EvolveCount { get; set; }
+
+    [JsonPropertyName("enemy_evolve_count")] [Key("enemy_evolve_count")]
+    public int EnemyEvolveCount { get; set; }
+}
+
+/// <summary>
+/// <c>colosseum_battle/finish</c> response. Per battle-finish.md, the client maps this to
+/// <c>ColosseumBattleFinishDetail</c> which is an empty <c>MatchFinishBase</c> subclass —
+/// no Colosseum-specific fields beyond the shared rank-battle-finish superset. Phase 2 v1
+/// emits the minimum required to keep the client's <c>BattleFinishResponsProcessing</c>
+/// happy.
+/// </summary>
+[MessagePackObject(keyAsPropertyName: true)]
+public sealed class ColosseumBattleFinishResponseDto
+{
+    [JsonPropertyName("battle_result")] [Key("battle_result")]
+    public int BattleResult { get; set; }
+}

SVSim.EmulatedEntrypoint/Models/Dtos/ArenaColosseum/ColosseumReceivedReward.cs

@@ -0,0 +1,26 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
+
+/// <summary>
+/// Per-entry shape for the <c>rewards</c> array on <c>/finish</c> + <c>/retire</c>. Richer
+/// than <c>RewardEntryDto</c> (which is the <c>reward_list</c> shape) — carries a display
+/// name. Distinct from the wallet-delta block: client renders <c>rewards</c> in the
+/// post-bracket popup while <c>reward_list</c> drives the silent wallet update.
+/// </summary>
+[MessagePackObject]
+public sealed class ColosseumReceivedReward
+{
+    [JsonPropertyName("reward_number")] [Key("reward_number")]
+    public int RewardNumber { get; set; }
+
+    [JsonPropertyName("reward_type")] [Key("reward_type")]
+    public int RewardType { get; set; }
+
+    [JsonPropertyName("reward_detail_id")] [Key("reward_detail_id")]
+    public long RewardDetailId { get; set; }
+
+    [JsonPropertyName("name")] [Key("name")]
+    public string Name { get; set; } = "";
+}

SVSim.EmulatedEntrypoint/Models/Dtos/Responses/ArenaColosseum/FinishResponse.cs

@@ -0,0 +1,27 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.ArenaColosseum;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Common.ArenaTwoPick;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Responses.ArenaColosseum;
+
+/// <summary>
+/// <c>POST /arena_colosseum/finish</c> and <c>POST /arena_colosseum/retire</c>. Wire-identical
+/// shape per finish.md §"Wire-shared with /retire" — endpoints differ in side-effects only:
+/// /finish emits per-round-completion + champion bonus and marks the entry champion;
+/// /retire emits the round-capped consolation. The client renders <c>rewards</c> in the
+/// post-bracket popup, applies wallet deltas via <c>reward_list</c>, and updates the
+/// status block via <c>colosseum_status</c>.
+/// </summary>
+[MessagePackObject]
+public sealed class FinishResponse
+{
+    [JsonPropertyName("rewards")] [Key("rewards")]
+    public List<ColosseumReceivedReward> Rewards { get; set; } = new();
+
+    [JsonPropertyName("reward_list")] [Key("reward_list")]
+    public List<RewardEntryDto> RewardList { get; set; } = new();
+
+    [JsonPropertyName("colosseum_status")] [Key("colosseum_status")]
+    public ColosseumOwnStatus ColosseumStatus { get; set; } = new();
+}

SVSim.EmulatedEntrypoint/Program.cs

@@ -107,6 +107,8 @@ public class Program
         builder.Services.AddScoped<IViewerStoryProgressRepository, ViewerStoryProgressRepository>();
         builder.Services.AddScoped<IArenaTwoPickRunRepository, ArenaTwoPickRunRepository>();
         builder.Services.AddScoped<IArenaColosseumRunRepository, ArenaColosseumRunRepository>();
+        builder.Services.AddScoped<SVSim.EmulatedEntrypoint.Services.ArenaColosseum.IColosseumProgressionService,
+                                   SVSim.EmulatedEntrypoint.Services.ArenaColosseum.ColosseumProgressionService>();
         builder.Services.AddScoped<IArenaTwoPickCardPoolService, ArenaTwoPickCardPoolService>();
         builder.Services.AddScoped<IArenaTwoPickService, ArenaTwoPickService>();
         builder.Services.AddScoped<IMatchContextBuilder, MatchContextBuilder>();
@@ -158,6 +160,11 @@ public class Program
             // (see Shadowverse_Code_2026-05-23/ApiType.cs), so PvpOnly: park forever, no AI fallback.
             new ModePolicy("rotation_free_battle", PolicyKind.PvpOnly),
             new ModePolicy("unlimited_free_battle", PolicyKind.PvpOnly),
+            // Colosseum (Grand Prix). Pre-promotion + post-promotion (rank) URLs each map
+            // to their own pair-up mode — the URL IS the signal per do-matching.md, and the
+            // node session has no way to ask the client "which bracket are you in?".
+            new ModePolicy("colosseum_battle", PolicyKind.PvpOnly),
+            new ModePolicy("colosseum_rank_battle", PolicyKind.PvpOnly),
         }));
         builder.Services.AddSingleton<IMatchingPairUpService, InProcessPairUp>();
         // Single resolver shared by every /do_matching family controller. Owns the

SVSim.EmulatedEntrypoint/Services/ArenaColosseum/ColosseumProgressionService.cs

@@ -0,0 +1,69 @@
+using SVSim.Database.Models;
+using SVSim.Database.Models.Config;
+
+namespace SVSim.EmulatedEntrypoint.Services.ArenaColosseum;
+
+public class ColosseumProgressionService : IColosseumProgressionService
+{
+    /// <summary>Colosseum-specific node signal — see do-matching.md §matching_state 3008.</summary>
+    public const int PromoteToRankMatchingState = 3008;
+
+    public bool ShouldPromoteToRankMatching(ViewerArenaColosseumRun run, int matchingState) =>
+        matchingState == PromoteToRankMatchingState && !run.IsRankMatching;
+
+    public AdvancementDecision DecideAdvancement(ViewerArenaColosseumRun run, ColosseumRoundsConfig rounds)
+    {
+        var currentRound = rounds.Rounds.FirstOrDefault(r => r.RoundId == run.RoundId);
+        var currentGroup = currentRound?.Groups.FirstOrDefault();
+        var maxRoundId = rounds.Rounds.Count == 0 ? run.RoundId : rounds.Rounds.Max(r => r.RoundId);
+
+        // No matching round config (e.g. content not seeded) — treat current state as terminal
+        // so the controller doesn't loop forever. Champion=false because we can't tell.
+        if (currentGroup is null)
+        {
+            return new AdvancementDecision(run.RoundId, IsBracketEnd: true, IsChampion: false);
+        }
+
+        // Cleared the breakthrough threshold this round.
+        if (run.WinCount >= currentGroup.BreakthroughNumber)
+        {
+            bool isFinal = run.RoundId >= maxRoundId;
+            return new AdvancementDecision(
+                NextRoundId: isFinal ? run.RoundId : run.RoundId + 1,
+                IsBracketEnd: isFinal,
+                IsChampion: isFinal);
+        }
+
+        // Exhausted the per-round battle cap without clearing — bracket ends at current round.
+        if (run.BattleCountThisRound >= currentGroup.MaxBattleCount)
+        {
+            return new AdvancementDecision(run.RoundId, IsBracketEnd: true, IsChampion: false);
+        }
+
+        // Mid-round, still playing.
+        return new AdvancementDecision(run.RoundId, IsBracketEnd: false, IsChampion: false);
+    }
+
+    public IReadOnlyList<ColosseumRoundsConfig.RewardEntry> BuildRetireRewards(
+        ViewerArenaColosseumRun run, ColosseumRoundsConfig rounds)
+    {
+        var round = rounds.Rounds.FirstOrDefault(r => r.RoundId == run.RoundId);
+        return round?.RetireRewards ?? new();
+    }
+
+    public IReadOnlyList<ColosseumRoundsConfig.RewardEntry> BuildFinishRewards(
+        ViewerArenaColosseumRun run, ColosseumRoundsConfig rounds)
+    {
+        var round = rounds.Rounds.FirstOrDefault(r => r.RoundId == run.RoundId);
+        var bundle = new List<ColosseumRoundsConfig.RewardEntry>();
+        if (round is not null)
+        {
+            bundle.AddRange(round.FinishRewards);
+        }
+        if (run.IsChampion)
+        {
+            bundle.AddRange(rounds.ChampionRewards);
+        }
+        return bundle;
+    }
+}

SVSim.EmulatedEntrypoint/Services/ArenaColosseum/IColosseumProgressionService.cs

@@ -0,0 +1,39 @@
+using SVSim.Database.Enums;
+using SVSim.Database.Models;
+using SVSim.Database.Models.Config;
+
+namespace SVSim.EmulatedEntrypoint.Services.ArenaColosseum;
+
+/// <summary>
+/// Pure-logic decisions for the Colosseum bracket lifecycle. Reads a
+/// <see cref="ViewerArenaColosseumRun"/> + <see cref="ColosseumRoundsConfig"/> snapshot and
+/// returns advancement / promotion / reward decisions. Side-effectful (debits, grants,
+/// run-row writes) live on the controllers — this service just computes.
+/// </summary>
+public interface IColosseumProgressionService
+{
+    /// <summary>True when the node signal <c>matching_state == 3008</c> indicates the run
+    /// has been promoted to the ranked bracket and we haven't already flipped the flag.
+    /// Subsequent battle URLs route to <c>colosseum_rank_battle/*</c>.</summary>
+    bool ShouldPromoteToRankMatching(ViewerArenaColosseumRun run, int matchingState);
+
+    /// <summary>Triggered post-match-finish when wins/losses cross thresholds. Returns the
+    /// next round id (or current if no change), whether the bracket has ended, and the
+    /// champion flag for the final-round-cleared case.</summary>
+    AdvancementDecision DecideAdvancement(ViewerArenaColosseumRun run, ColosseumRoundsConfig rounds);
+
+    /// <summary>Bundle to grant on <c>/retire</c>. Reads
+    /// <see cref="ColosseumRoundsConfig.RoundEntry.RetireRewards"/> for the run's
+    /// <see cref="ViewerArenaColosseumRun.RoundId"/>. Empty when no matching round.</summary>
+    IReadOnlyList<ColosseumRoundsConfig.RewardEntry> BuildRetireRewards(
+        ViewerArenaColosseumRun run, ColosseumRoundsConfig rounds);
+
+    /// <summary>Bundle to grant on <c>/finish</c>. Combines the current round's
+    /// <see cref="ColosseumRoundsConfig.RoundEntry.FinishRewards"/> with
+    /// <see cref="ColosseumRoundsConfig.ChampionRewards"/> when the run is a champion.</summary>
+    IReadOnlyList<ColosseumRoundsConfig.RewardEntry> BuildFinishRewards(
+        ViewerArenaColosseumRun run, ColosseumRoundsConfig rounds);
+}
+
+/// <summary>Output of <see cref="IColosseumProgressionService.DecideAdvancement"/>.</summary>
+public sealed record AdvancementDecision(int NextRoundId, bool IsBracketEnd, bool IsChampion);

SVSim.EmulatedEntrypoint/Services/IMatchContextBuilder.cs

@@ -24,4 +24,13 @@ public interface IMatchContextBuilder
     /// no deck at that slot.
     /// </summary>
     Task<MatchContext> BuildForRankBattleAsync(long viewerId, Format format, int deckNo);
+
+    /// <summary>
+    /// Build a context for an Arena Colosseum bracket match — reads the active
+    /// <c>ViewerArenaColosseumRun</c>'s registered deck slot (single-deck v1) via
+    /// <c>IDeckRepository.GetDeck</c> (NOT viewer-graph traversal per
+    /// <c>project_ef_nav_include_pitfall</c>). Throws when the run is missing or no deck
+    /// has been registered yet.
+    /// </summary>
+    Task<MatchContext> BuildForColosseumAsync(long viewerId);
 }

SVSim.EmulatedEntrypoint/Services/MatchContextBuilder.cs

@@ -11,17 +11,20 @@ namespace SVSim.EmulatedEntrypoint.Services;
 public class MatchContextBuilder : IMatchContextBuilder
 {
     private readonly IArenaTwoPickRunRepository _runs;
+    private readonly IArenaColosseumRunRepository _colosseumRuns;
     private readonly IViewerRepository _viewers;
     private readonly IDeckRepository _decks;
     private readonly IGameConfigService _config;
 
     public MatchContextBuilder(
         IArenaTwoPickRunRepository runs,
+        IArenaColosseumRunRepository colosseumRuns,
         IViewerRepository viewers,
         IDeckRepository decks,
         IGameConfigService config)
     {
         _runs = runs;
+        _colosseumRuns = colosseumRuns;
         _viewers = viewers;
         _decks = decks;
         _config = config;
@@ -120,4 +123,58 @@ public class MatchContextBuilder : IMatchContextBuilder
             IsOfficial: viewer.Info.IsOfficial ? 1 : 0,
             BattleModeId: BattleModes.TakeTwo);
     }
+
+    public async Task<MatchContext> BuildForColosseumAsync(long viewerId)
+    {
+        var run = await _colosseumRuns.GetByViewerIdAsync(viewerId)
+            ?? throw new InvalidOperationException("arena_colosseum_no_active_run");
+
+        // v1 single-deck slot — Round-3 multi-deck format is deferred per plan.
+        var deckNos = JsonSerializer.Deserialize<List<int>>(run.RegisteredDeckNoListJson) ?? new();
+        if (deckNos.Count == 0)
+        {
+            throw new InvalidOperationException("arena_colosseum_no_deck_registered");
+        }
+        var deckNo = deckNos[0];
+
+        var viewer = await _viewers.LoadForMatchContextAsync(viewerId)
+            ?? throw new InvalidOperationException($"viewer {viewerId} not found");
+
+        var deck = await _decks.GetDeck(viewerId, run.DeckFormat, deckNo)
+            ?? throw new InvalidOperationException(
+                $"viewer {viewerId} has no deck #{deckNo} for format {run.DeckFormat}");
+
+        var defaults = _config.Get<DefaultLoadoutConfig>();
+        var emblemId = viewer.Info.SelectedEmblem.Id != 0
+            ? viewer.Info.SelectedEmblem.Id.ToString()
+            : defaults.EmblemId.ToString();
+        var degreeId = viewer.Info.SelectedDegree.Id != 0
+            ? viewer.Info.SelectedDegree.Id.ToString()
+            : defaults.DegreeId.ToString();
+        var charaId = run.LeaderSkinId != 0
+            ? run.LeaderSkinId.ToString()
+            : deck.LeaderSkin.Id != 0
+                ? deck.LeaderSkin.Id.ToString()
+                : deck.Class.Id.ToString();
+        var sleeveId = deck.Sleeve.Id != 0
+            ? deck.Sleeve.Id.ToString()
+            : defaults.SleeveId.ToString();
+        var deckCardIds = deck.Cards
+            .SelectMany(c => Enumerable.Repeat(c.Card.Id, c.Count))
+            .ToList();
+
+        return new MatchContext(
+            SelfDeckCardIds: deckCardIds,
+            ClassId: (CardClass)deck.Class.Id,
+            CharaId: charaId,
+            CardMasterName: "card_master_node_10015",
+            CountryCode: viewer.Info.CountryCode ?? string.Empty,
+            UserName: viewer.DisplayName,
+            SleeveId: sleeveId,
+            EmblemId: emblemId,
+            DegreeId: degreeId,
+            FieldId: 43,
+            IsOfficial: viewer.Info.IsOfficial ? 1 : 0,
+            BattleModeId: BattleModes.TakeTwo);
+    }
 }