feat: surface Copilot usage and quota data across the UI

Add three layers of usage visibility:

- ChatPane footer: premium request count, AIU consumed, and quota
  remaining below the existing context-window bar
- Settings / CopilotStatusCard: on-demand account quota section with
  progress bars, overage indicators, and reset dates fetched via
  the new get-quota sidecar command
- Activity Panel: per-agent token/cost/duration totals on each agent
  row and a Session Usage summary section between agents and timeline

Backend (sidecar):
- New get-quota command using SDK account.getQuota RPC
- New assistant-usage turn-scoped event from SDK assistant.usage
- QuotaSnapshotMapper for both typed and untyped SDK quota payloads
- DTOs: GetQuotaCommandDto, QuotaSnapshotDto, AccountQuotaResultEventDto,
  AssistantUsageEventDto

Frontend:
- Shared types: AssistantUsageEvent, QuotaSnapshot, GetQuotaCommand
- IPC bridge: getQuota channel, assistant-usage event dispatch
- State: SessionRequestUsageMap accumulator with per-agent breakdown
- 8 new tests for accumulator logic and formatting helpers

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

sidecar/src/Aryx.AgentHost/Services/CopilotSessionManager.cs

@@ -1,10 +1,19 @@
 using Aryx.AgentHost.Contracts;
 using GitHub.Copilot.SDK;
+using GitHub.Copilot.SDK.Rpc;
 
 namespace Aryx.AgentHost.Services;
 
 internal sealed class CopilotSessionManager : ICopilotSessionManager
 {
+    public async Task<IReadOnlyDictionary<string, QuotaSnapshotDto>> GetQuotaAsync(
+        CancellationToken cancellationToken)
+    {
+        await using CopilotClient client = await CreateStartedClientAsync(cancellationToken).ConfigureAwait(false);
+        AccountGetQuotaResult result = await client.Rpc.Account.GetQuotaAsync(cancellationToken).ConfigureAwait(false);
+        return QuotaSnapshotMapper.Map(result.QuotaSnapshots);
+    }
+
     public async Task<IReadOnlyList<CopilotSessionInfoDto>> ListSessionsAsync(
         CopilotSessionListFilterDto? filter,
         CancellationToken cancellationToken)

sidecar/src/Aryx.AgentHost/Services/CopilotTurnExecutionState.cs

@@ -127,6 +127,10 @@ internal sealed class CopilotTurnExecutionState
                     _pendingEvents.Enqueue(CreateHookLifecycleEvent(agent, "end", hookEnd.Data));
                 }
                 break;
+            case AssistantUsageEvent assistantUsage:
+                ActiveAgent = agent;
+                _pendingEvents.Enqueue(CreateAssistantUsageEvent(agent, assistantUsage.Data));
+                break;
             case SessionUsageInfoEvent usageInfo:
                 ActiveAgent = agent;
                 _pendingEvents.Enqueue(CreateUsageEvent(agent, usageInfo.Data));
@@ -410,6 +414,29 @@ internal sealed class CopilotTurnExecutionState
         };
     }
 
+    private AssistantUsageEventDto CreateAssistantUsageEvent(
+        AgentIdentity agent,
+        AssistantUsageData? data)
+    {
+        return new AssistantUsageEventDto
+        {
+            Type = "assistant-usage",
+            RequestId = _command.RequestId,
+            SessionId = _command.SessionId,
+            AgentId = agent.AgentId,
+            AgentName = agent.AgentName,
+            Model = data?.Model ?? string.Empty,
+            InputTokens = data?.InputTokens,
+            OutputTokens = data?.OutputTokens,
+            CacheReadTokens = data?.CacheReadTokens,
+            CacheWriteTokens = data?.CacheWriteTokens,
+            Cost = data?.Cost,
+            Duration = data?.Duration,
+            TotalNanoAiu = data?.CopilotUsage?.TotalNanoAiu,
+            QuotaSnapshots = QuotaSnapshotMapper.MapOrNull(data?.QuotaSnapshots),
+        };
+    }
+
     private SessionUsageEventDto CreateUsageEvent(AgentIdentity agent, SessionUsageInfoData? data)
     {
         return new SessionUsageEventDto

sidecar/src/Aryx.AgentHost/Services/ICopilotSessionManager.cs

@@ -12,5 +12,8 @@ public interface ICopilotSessionManager
         string? aryxSessionId,
         string? copilotSessionId,
         CancellationToken cancellationToken);
+
+    Task<IReadOnlyDictionary<string, QuotaSnapshotDto>> GetQuotaAsync(
+        CancellationToken cancellationToken);
 }
 

sidecar/src/Aryx.AgentHost/Services/QuotaSnapshotMapper.cs

@@ -0,0 +1,105 @@
+using System.Text.Json;
+using Aryx.AgentHost.Contracts;
+using GitHub.Copilot.SDK.Rpc;
+
+namespace Aryx.AgentHost.Services;
+
+internal static class QuotaSnapshotMapper
+{
+    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web)
+    {
+        PropertyNameCaseInsensitive = true,
+    };
+
+    public static Dictionary<string, QuotaSnapshotDto> Map(
+        IReadOnlyDictionary<string, AccountGetQuotaResultQuotaSnapshotsValue>? snapshots)
+    {
+        Dictionary<string, QuotaSnapshotDto> mapped = new(StringComparer.Ordinal);
+        if (snapshots is null)
+        {
+            return mapped;
+        }
+
+        foreach ((string key, AccountGetQuotaResultQuotaSnapshotsValue snapshot) in snapshots)
+        {
+            if (string.IsNullOrWhiteSpace(key))
+            {
+                continue;
+            }
+
+            mapped[key.Trim()] = Map(snapshot);
+        }
+
+        return mapped;
+    }
+
+    public static Dictionary<string, QuotaSnapshotDto>? MapOrNull(
+        IReadOnlyDictionary<string, object>? snapshots)
+    {
+        if (snapshots is not { Count: > 0 })
+        {
+            return null;
+        }
+
+        Dictionary<string, QuotaSnapshotDto> mapped = new(StringComparer.Ordinal);
+        foreach ((string key, object snapshot) in snapshots)
+        {
+            if (string.IsNullOrWhiteSpace(key))
+            {
+                continue;
+            }
+
+            QuotaSnapshotDto? mappedSnapshot = TryMap(snapshot);
+            if (mappedSnapshot is null)
+            {
+                continue;
+            }
+
+            mapped[key.Trim()] = mappedSnapshot;
+        }
+
+        return mapped.Count == 0 ? null : mapped;
+    }
+
+    public static QuotaSnapshotDto Map(AccountGetQuotaResultQuotaSnapshotsValue snapshot)
+    {
+        ArgumentNullException.ThrowIfNull(snapshot);
+
+        return new QuotaSnapshotDto
+        {
+            EntitlementRequests = snapshot.EntitlementRequests,
+            UsedRequests = snapshot.UsedRequests,
+            RemainingPercentage = snapshot.RemainingPercentage,
+            Overage = snapshot.Overage,
+            OverageAllowedWithExhaustedQuota = snapshot.OverageAllowedWithExhaustedQuota,
+            ResetDate = snapshot.ResetDate,
+        };
+    }
+
+    private static QuotaSnapshotDto? TryMap(object? snapshot)
+    {
+        if (snapshot is null)
+        {
+            return null;
+        }
+
+        if (snapshot is AccountGetQuotaResultQuotaSnapshotsValue typedSnapshot)
+        {
+            return Map(typedSnapshot);
+        }
+
+        JsonElement element = snapshot is JsonElement jsonElement
+            ? jsonElement
+            : JsonSerializer.SerializeToElement(snapshot, JsonOptions);
+
+        if (element.ValueKind != JsonValueKind.Object)
+        {
+            return null;
+        }
+
+        AccountGetQuotaResultQuotaSnapshotsValue? deserialized =
+            element.Deserialize<AccountGetQuotaResultQuotaSnapshotsValue>(JsonOptions);
+
+        return deserialized is null ? null : Map(deserialized);
+    }
+}

sidecar/src/Aryx.AgentHost/Services/SidecarProtocolHost.cs

@@ -18,6 +18,7 @@ public sealed class SidecarProtocolHost
     private const string ListSessionsCommandType = "list-sessions";
     private const string DeleteSessionCommandType = "delete-session";
     private const string DisconnectSessionCommandType = "disconnect-session";
+    private const string GetQuotaCommandType = "get-quota";
     private const string AskUserToolName = "ask_user";
     private static readonly HashSet<string> ExcludedRuntimeToolNames = new(StringComparer.OrdinalIgnoreCase)
     {
@@ -82,6 +83,7 @@ public sealed class SidecarProtocolHost
             [ListSessionsCommandType] = HandleListSessionsAsync,
             [DeleteSessionCommandType] = HandleDeleteSessionAsync,
             [DisconnectSessionCommandType] = HandleDisconnectSessionAsync,
+            [GetQuotaCommandType] = HandleGetQuotaAsync,
         };
     }
 
@@ -313,6 +315,23 @@ public sealed class SidecarProtocolHost
         }, context.CancellationToken).ConfigureAwait(false);
     }
 
+    private async Task HandleGetQuotaAsync(CommandContext context)
+    {
+        _ = DeserializeCommand<GetQuotaCommandDto>(context);
+        IReadOnlyDictionary<string, QuotaSnapshotDto> quotaSnapshots =
+            await _sessionManager.GetQuotaAsync(context.CancellationToken).ConfigureAwait(false);
+
+        await WriteAsync(context.Output, new AccountQuotaResultEventDto
+        {
+            Type = "quota-result",
+            RequestId = context.Envelope.RequestId,
+            QuotaSnapshots = quotaSnapshots.ToDictionary(
+                snapshot => snapshot.Key,
+                snapshot => snapshot.Value,
+                StringComparer.Ordinal),
+        }, context.CancellationToken).ConfigureAwait(false);
+    }
+
     private TCommand DeserializeCommand<TCommand>(CommandContext context)
         where TCommand : SidecarCommandEnvelope
     {