fix(db): add index on agent_task_queue(issue_id) for usage queries

The GetIssueUsageSummary query joins agent_task_queue filtered by
issue_id across all statuses. The existing partial index (migration 022)
only covers queued/dispatched rows, so completed tasks require a
sequential scan. Add a general index to prevent performance degradation
as task volume grows.

packages/core/api/client.ts

@@ -30,6 +30,7 @@ import type {
   CreatePersonalAccessTokenRequest,
   CreatePersonalAccessTokenResponse,
   RuntimeUsage,
+  IssueUsageSummary,
   RuntimeHourlyActivity,
   RuntimePing,
   RuntimeUpdate,
@@ -415,6 +416,10 @@ export class ApiClient {
     return this.fetch(`/api/issues/${issueId}/task-runs`);
   }
 
+  async getIssueUsage(issueId: string): Promise<IssueUsageSummary> {
+    return this.fetch(`/api/issues/${issueId}/usage`);
+  }
+
   async cancelTask(issueId: string, taskId: string): Promise<AgentTask> {
     return this.fetch(`/api/issues/${issueId}/tasks/${taskId}/cancel`, {
       method: "POST",

packages/core/issues/queries.ts

@@ -12,6 +12,7 @@ export const issueKeys = {
   reactions: (issueId: string) => ["issues", "reactions", issueId] as const,
   subscribers: (issueId: string) =>
     ["issues", "subscribers", issueId] as const,
+  usage: (issueId: string) => ["issues", "usage", issueId] as const,
 };
 
 export const CLOSED_PAGE_SIZE = 50;
@@ -79,3 +80,10 @@ export function issueSubscribersOptions(issueId: string) {
     queryFn: () => api.listIssueSubscribers(issueId),
   });
 }
+
+export function issueUsageOptions(issueId: string) {
+  return queryOptions({
+    queryKey: issueKeys.usage(issueId),
+    queryFn: () => api.getIssueUsage(issueId),
+  });
+}

packages/core/types/agent.ts

@@ -138,6 +138,14 @@ export interface RuntimePing {
   updated_at: string;
 }
 
+export interface IssueUsageSummary {
+  total_input_tokens: number;
+  total_output_tokens: number;
+  total_cache_read_tokens: number;
+  total_cache_write_tokens: number;
+  task_count: number;
+}
+
 export interface RuntimeUsage {
   runtime_id: string;
   date: string;

packages/core/types/index.ts

@@ -20,6 +20,7 @@ export type {
   RuntimePingStatus,
   RuntimeUpdate,
   RuntimeUpdateStatus,
+  IssueUsageSummary,
 } from "./agent";
 export type { Workspace, WorkspaceRepo, Member, MemberRole, User, MemberWithUser } from "./workspace";
 export type { InboxItem, InboxSeverity, InboxItemType } from "./inbox";

packages/views/issues/components/issue-detail.tsx

@@ -70,7 +70,7 @@ import { useAuthStore } from "@multica/core/auth";
 import { useWorkspaceStore } from "@multica/core/workspace";
 import { useActorName } from "@multica/core/workspace/hooks";
 import { useWorkspaceId } from "@multica/core/hooks";
-import { issueListOptions, issueDetailOptions, childIssuesOptions } from "@multica/core/issues/queries";
+import { issueListOptions, issueDetailOptions, childIssuesOptions, issueUsageOptions } from "@multica/core/issues/queries";
 import { memberListOptions, agentListOptions } from "@multica/core/workspace/queries";
 import { useUpdateIssue, useDeleteIssue } from "@multica/core/issues/mutations";
 import { useIssueTimeline } from "../hooks/use-issue-timeline";
@@ -193,6 +193,16 @@ function formatActivity(
 }
 
 
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+function formatTokenCount(n: number): string {
+  if (n >= 1_000_000) return `${(n / 1_000_000).toFixed(1)}M`;
+  if (n >= 1_000) return `${(n / 1_000).toFixed(1)}k`;
+  return String(n);
+}
+
 // ---------------------------------------------------------------------------
 // Property row
 // ---------------------------------------------------------------------------
@@ -285,6 +295,9 @@ export function IssueDetail({ issueId, onDelete, defaultSidebarOpen = true, layo
     subscribers, loading: subscribersLoading, isSubscribed, toggleSubscribe: handleToggleSubscribe, toggleSubscriber,
   } = useIssueSubscribers(id, user?.id);
 
+  // Token usage
+  const { data: usage } = useQuery(issueUsageOptions(id));
+
   // Sub-issue queries
   const parentIssueId = issue?.parent_issue_id;
   const { data: parentIssue = null } = useQuery({
@@ -1271,6 +1284,34 @@ export function IssueDetail({ issueId, onDelete, defaultSidebarOpen = true, layo
             </div>}
           </div>
 
+          {/* Token usage */}
+          {usage && usage.task_count > 0 && (
+            <div>
+              <div className="text-xs font-medium mb-2 flex items-center gap-1">
+                <ChevronRight className="h-3.5 w-3.5 shrink-0 text-muted-foreground rotate-90" />
+                Token usage
+              </div>
+              <div className="space-y-0.5 pl-2">
+                <PropRow label="Input">
+                  <span className="text-muted-foreground">{formatTokenCount(usage.total_input_tokens)}</span>
+                </PropRow>
+                <PropRow label="Output">
+                  <span className="text-muted-foreground">{formatTokenCount(usage.total_output_tokens)}</span>
+                </PropRow>
+                {(usage.total_cache_read_tokens > 0 || usage.total_cache_write_tokens > 0) && (
+                  <PropRow label="Cache">
+                    <span className="text-muted-foreground">
+                      {formatTokenCount(usage.total_cache_read_tokens)} read / {formatTokenCount(usage.total_cache_write_tokens)} write
+                    </span>
+                  </PropRow>
+                )}
+                <PropRow label="Runs">
+                  <span className="text-muted-foreground">{usage.task_count}</span>
+                </PropRow>
+              </div>
+            </div>
+          )}
+
         </div>
       </div>
       </ResizablePanel>

server/cmd/server/router.go

@@ -175,6 +175,7 @@ func NewRouter(pool *pgxpool.Pool, hub *realtime.Hub, bus *events.Bus) chi.Route
 					r.Get("/active-task", h.GetActiveTaskForIssue)
 					r.Post("/tasks/{taskId}/cancel", h.CancelTask)
 					r.Get("/task-runs", h.ListTasksByIssue)
+					r.Get("/usage", h.GetIssueUsage)
 					r.Post("/reactions", h.AddIssueReaction)
 					r.Delete("/reactions", h.RemoveIssueReaction)
 					r.Get("/attachments", h.ListAttachments)

server/internal/handler/daemon.go

@@ -627,3 +627,22 @@ func (h *Handler) ListTasksByIssue(w http.ResponseWriter, r *http.Request) {
 
 	writeJSON(w, http.StatusOK, resp)
 }
+
+// GetIssueUsage returns aggregated token usage for all tasks belonging to an issue.
+func (h *Handler) GetIssueUsage(w http.ResponseWriter, r *http.Request) {
+	issueID := chi.URLParam(r, "id")
+
+	row, err := h.Queries.GetIssueUsageSummary(r.Context(), parseUUID(issueID))
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to get issue usage")
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]any{
+		"total_input_tokens":       row.TotalInputTokens,
+		"total_output_tokens":      row.TotalOutputTokens,
+		"total_cache_read_tokens":  row.TotalCacheReadTokens,
+		"total_cache_write_tokens": row.TotalCacheWriteTokens,
+		"task_count":               row.TaskCount,
+	})
+}

server/migrations/035_task_queue_issue_id_index.down.sql

@@ -0,0 +1 @@
+DROP INDEX IF EXISTS idx_agent_task_queue_issue_id;

server/migrations/035_task_queue_issue_id_index.up.sql

@@ -0,0 +1,5 @@
+-- Add a general index on agent_task_queue(issue_id) to support aggregation
+-- queries like GetIssueUsageSummary that scan across all task statuses.
+-- (Migration 022 only covers queued/dispatched rows via a partial index.)
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_agent_task_queue_issue_id
+    ON agent_task_queue (issue_id);

server/pkg/db/generated/task_usage.sql.go

@@ -11,6 +11,39 @@ import (
 	"github.com/jackc/pgx/v5/pgtype"
 )
 
+const getIssueUsageSummary = `-- name: GetIssueUsageSummary :one
+SELECT
+    COALESCE(SUM(tu.input_tokens), 0)::bigint AS total_input_tokens,
+    COALESCE(SUM(tu.output_tokens), 0)::bigint AS total_output_tokens,
+    COALESCE(SUM(tu.cache_read_tokens), 0)::bigint AS total_cache_read_tokens,
+    COALESCE(SUM(tu.cache_write_tokens), 0)::bigint AS total_cache_write_tokens,
+    COUNT(DISTINCT tu.task_id)::int AS task_count
+FROM task_usage tu
+JOIN agent_task_queue atq ON atq.id = tu.task_id
+WHERE atq.issue_id = $1
+`
+
+type GetIssueUsageSummaryRow struct {
+	TotalInputTokens      int64 `json:"total_input_tokens"`
+	TotalOutputTokens     int64 `json:"total_output_tokens"`
+	TotalCacheReadTokens  int64 `json:"total_cache_read_tokens"`
+	TotalCacheWriteTokens int64 `json:"total_cache_write_tokens"`
+	TaskCount             int32 `json:"task_count"`
+}
+
+func (q *Queries) GetIssueUsageSummary(ctx context.Context, issueID pgtype.UUID) (GetIssueUsageSummaryRow, error) {
+	row := q.db.QueryRow(ctx, getIssueUsageSummary, issueID)
+	var i GetIssueUsageSummaryRow
+	err := row.Scan(
+		&i.TotalInputTokens,
+		&i.TotalOutputTokens,
+		&i.TotalCacheReadTokens,
+		&i.TotalCacheWriteTokens,
+		&i.TaskCount,
+	)
+	return i, err
+}
+
 const getTaskUsage = `-- name: GetTaskUsage :many
 SELECT id, task_id, provider, model, input_tokens, output_tokens, cache_read_tokens, cache_write_tokens, created_at FROM task_usage
 WHERE task_id = $1

server/pkg/db/queries/task_usage.sql

@@ -45,3 +45,14 @@ WHERE a.workspace_id = $1
   AND atq.created_at >= @since::timestamptz
 GROUP BY tu.model
 ORDER BY (SUM(tu.input_tokens) + SUM(tu.output_tokens)) DESC;
+
+-- name: GetIssueUsageSummary :one
+SELECT
+    COALESCE(SUM(tu.input_tokens), 0)::bigint AS total_input_tokens,
+    COALESCE(SUM(tu.output_tokens), 0)::bigint AS total_output_tokens,
+    COALESCE(SUM(tu.cache_read_tokens), 0)::bigint AS total_cache_read_tokens,
+    COALESCE(SUM(tu.cache_write_tokens), 0)::bigint AS total_cache_write_tokens,
+    COUNT(DISTINCT tu.task_id)::int AS task_count
+FROM task_usage tu
+JOIN agent_task_queue atq ON atq.id = tu.task_id
+WHERE atq.issue_id = $1;