fix: Add 'running' field to sessions_list for accurate subagent status

sessions_list was reporting totalTokens: 0 for actively running subagent
sessions because token counts are only persisted at run completion.

This caused orchestration logic to incorrectly determine agent availability.

Changes:
- Add getRunningSubagentSessions() to subagent-registry.ts
- Add isSubagentSessionRunning() helper for individual checks
- Modify listSessionsFromStore() to include 'running' field
- Update GatewaySessionRow and SessionListRow types

The 'running' field is true when a session has an active subagent run
(startedAt is set but endedAt is not).

Fixes: #2129

src/agents/subagent-registry.ts

@@ -369,3 +369,32 @@ export function listSubagentRunsForRequester(requesterSessionKey: string): Subag
 export function initSubagentRegistry() {
   restoreSubagentRunsOnce();
 }
+
+/**
+ * Check if a session key has an active (in-progress) subagent run.
+ * Returns true if a run exists with startedAt but no endedAt.
+ */
+export function isSubagentSessionRunning(childSessionKey: string): boolean {
+  const key = childSessionKey.trim();
+  if (!key) return false;
+  for (const entry of subagentRuns.values()) {
+    if (entry.childSessionKey === key && entry.startedAt && !entry.endedAt) {
+      return true;
+    }
+  }
+  return false;
+}
+
+/**
+ * Get all currently running subagent session keys.
+ * Returns a Set of session keys that have active runs.
+ */
+export function getRunningSubagentSessions(): Set<string> {
+  const running = new Set<string>();
+  for (const entry of subagentRuns.values()) {
+    if (entry.startedAt && !entry.endedAt) {
+      running.add(entry.childSessionKey);
+    }
+  }
+  return running;
+}

src/agents/tools/sessions-helpers.ts

@@ -28,6 +28,8 @@ export type SessionListRow = {
   model?: string;
   contextTokens?: number | null;
   totalTokens?: number | null;
+  /** True if this session has an active subagent run in progress */
+  running?: boolean;
   thinkingLevel?: string;
   verboseLevel?: string;
   systemSent?: boolean;

src/agents/tools/sessions-list-tool.ts

@@ -169,6 +169,7 @@ export function createSessionsListTool(opts?: {
           model: typeof entry.model === "string" ? entry.model : undefined,
           contextTokens: typeof entry.contextTokens === "number" ? entry.contextTokens : undefined,
           totalTokens: typeof entry.totalTokens === "number" ? entry.totalTokens : undefined,
+          running: typeof entry.running === "boolean" ? entry.running : undefined,
           thinkingLevel: typeof entry.thinkingLevel === "string" ? entry.thinkingLevel : undefined,
           verboseLevel: typeof entry.verboseLevel === "string" ? entry.verboseLevel : undefined,
           systemSent: typeof entry.systemSent === "boolean" ? entry.systemSent : undefined,

src/gateway/session-utils.ts

@@ -2,6 +2,7 @@ import fs from "node:fs";
 import path from "node:path";
 
 import { resolveAgentWorkspaceDir, resolveDefaultAgentId } from "../agents/agent-scope.js";
+import { getRunningSubagentSessions } from "../agents/subagent-registry.js";
 import { lookupContextTokens } from "../agents/context.js";
 import { DEFAULT_CONTEXT_TOKENS, DEFAULT_MODEL, DEFAULT_PROVIDER } from "../agents/defaults.js";
 import { resolveConfiguredModelRef } from "../agents/model-selection.js";
@@ -468,6 +469,9 @@ export function listSessionsFromStore(params: {
   const { cfg, storePath, store, opts } = params;
   const now = Date.now();
 
+  // Get set of currently running subagent sessions for accurate status reporting
+  const runningSubagents = getRunningSubagentSessions();
+
   const includeGlobal = opts.includeGlobal === true;
   const includeUnknown = opts.includeUnknown === true;
   const includeDerivedTitles = opts.includeDerivedTitles === true;
@@ -554,6 +558,8 @@ export function listSessionsFromStore(params: {
         inputTokens: entry?.inputTokens,
         outputTokens: entry?.outputTokens,
         totalTokens: total,
+        // Check if this is a running subagent (has active run but may not have tokens yet)
+        running: runningSubagents.has(key),
         responseUsage: entry?.responseUsage,
         modelProvider: entry?.modelProvider,
         model: entry?.model,

src/gateway/session-utils.types.ts

@@ -33,6 +33,8 @@ export type GatewaySessionRow = {
   inputTokens?: number;
   outputTokens?: number;
   totalTokens?: number;
+  /** True if this session has an active subagent run in progress */
+  running?: boolean;
   responseUsage?: "on" | "off" | "tokens" | "full";
   modelProvider?: string;
   model?: string;