fix(cli): display correct model for sub-agents in sessions list (#18660)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: ba54c5a351
Co-authored-by: robbyczgw-cla <239660374+robbyczgw-cla@users.noreply.github.com>
Co-authored-by: gumadeiras <5599352+gumadeiras@users.noreply.github.com>
Reviewed-by: @gumadeiras

src/commands/sessions.model-resolution.test.ts

@@ -0,0 +1,108 @@
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("../config/config.js", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("../config/config.js")>();
+  return {
+    ...actual,
+    loadConfig: () => ({
+      agents: {
+        defaults: {
+          model: { primary: "pi:opus" },
+          models: { "pi:opus": {} },
+          contextTokens: 32000,
+        },
+      },
+    }),
+  };
+});
+
+import { sessionsCommand } from "./sessions.js";
+
+const makeRuntime = () => {
+  const logs: string[] = [];
+  return {
+    runtime: {
+      log: (msg: unknown) => logs.push(String(msg)),
+      error: (msg: unknown) => {
+        throw new Error(String(msg));
+      },
+      exit: (code: number) => {
+        throw new Error(`exit ${code}`);
+      },
+    },
+    logs,
+  } as const;
+};
+
+const writeStore = (data: unknown) => {
+  const file = path.join(
+    os.tmpdir(),
+    `sessions-model-${Date.now()}-${Math.random().toString(16).slice(2)}.json`,
+  );
+  fs.writeFileSync(file, JSON.stringify(data, null, 2));
+  return file;
+};
+
+describe("sessionsCommand model resolution", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date("2025-12-06T00:00:00Z"));
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("prefers runtime model fields for subagent sessions in JSON output", async () => {
+    const store = writeStore({
+      "agent:research:subagent:demo": {
+        sessionId: "subagent-1",
+        updatedAt: Date.now() - 2 * 60_000,
+        modelProvider: "openai-codex",
+        model: "gpt-5.3-codex",
+        modelOverride: "pi:opus",
+      },
+    });
+
+    const { runtime, logs } = makeRuntime();
+    await sessionsCommand({ store, json: true }, runtime);
+
+    fs.rmSync(store);
+
+    const payload = JSON.parse(logs[0] ?? "{}") as {
+      sessions?: Array<{
+        key: string;
+        model?: string | null;
+      }>;
+    };
+    const subagent = payload.sessions?.find((row) => row.key === "agent:research:subagent:demo");
+    expect(subagent?.model).toBe("gpt-5.3-codex");
+  });
+
+  it("falls back to modelOverride when runtime model is missing", async () => {
+    const store = writeStore({
+      "agent:research:subagent:demo": {
+        sessionId: "subagent-2",
+        updatedAt: Date.now() - 2 * 60_000,
+        modelOverride: "openai-codex/gpt-5.3-codex",
+      },
+    });
+
+    const { runtime, logs } = makeRuntime();
+    await sessionsCommand({ store, json: true }, runtime);
+
+    fs.rmSync(store);
+
+    const payload = JSON.parse(logs[0] ?? "{}") as {
+      sessions?: Array<{
+        key: string;
+        model?: string | null;
+      }>;
+    };
+    const subagent = payload.sessions?.find((row) => row.key === "agent:research:subagent:demo");
+    expect(subagent?.model).toBe("gpt-5.3-codex");
+  });
+});

src/commands/sessions.ts

@@ -8,9 +8,10 @@ import {
   resolveStorePath,
   type SessionEntry,
 } from "../config/sessions.js";
-import { classifySessionKey } from "../gateway/session-utils.js";
+import { classifySessionKey, resolveSessionModelRef } from "../gateway/session-utils.js";
 import { info } from "../globals.js";
 import { formatTimeAgo } from "../infra/format-time/format-relative.ts";
+import { parseAgentSessionKey } from "../routing/session-key.js";
 import type { RuntimeEnv } from "../runtime.js";
 import { isRich, theme } from "../terminal/theme.js";
 
@@ -33,6 +34,9 @@ type SessionRow = {
   totalTokens?: number;
   totalTokensFresh?: boolean;
   model?: string;
+  modelProvider?: string;
+  providerOverride?: string;
+  modelOverride?: string;
   contextTokens?: number;
 };
 
@@ -153,6 +157,9 @@ function toRows(store: Record<string, SessionEntry>): SessionRow[] {
         totalTokens: entry?.totalTokens,
         totalTokensFresh: entry?.totalTokensFresh,
         model: entry?.model,
+        modelProvider: entry?.modelProvider,
+        providerOverride: entry?.providerOverride,
+        modelOverride: entry?.modelOverride,
         contextTokens: entry?.contextTokens,
       } satisfies SessionRow;
     })
@@ -205,15 +212,23 @@ export async function sessionsCommand(
           path: storePath,
           count: rows.length,
           activeMinutes: activeMinutes ?? null,
-          sessions: rows.map((r) => ({
-            ...r,
-            totalTokens: resolveFreshSessionTotalTokens(r) ?? null,
-            totalTokensFresh:
-              typeof r.totalTokens === "number" ? r.totalTokensFresh !== false : false,
-            contextTokens:
-              r.contextTokens ?? lookupContextTokens(r.model) ?? configContextTokens ?? null,
-            model: r.model ?? configModel ?? null,
-          })),
+          sessions: rows.map((r) => {
+            const resolvedModel = resolveSessionModelRef(
+              cfg,
+              r,
+              parseAgentSessionKey(r.key)?.agentId,
+            );
+            const model = resolvedModel.model ?? configModel;
+            return {
+              ...r,
+              totalTokens: resolveFreshSessionTotalTokens(r) ?? null,
+              totalTokensFresh:
+                typeof r.totalTokens === "number" ? r.totalTokensFresh !== false : false,
+              contextTokens:
+                r.contextTokens ?? lookupContextTokens(model) ?? configContextTokens ?? null,
+              model,
+            };
+          }),
         },
         null,
         2,
@@ -245,7 +260,8 @@ export async function sessionsCommand(
   runtime.log(rich ? theme.heading(header) : header);
 
   for (const row of rows) {
-    const model = row.model ?? configModel;
+    const resolvedModel = resolveSessionModelRef(cfg, row, parseAgentSessionKey(row.key)?.agentId);
+    const model = resolvedModel.model ?? configModel;
     const contextTokens = row.contextTokens ?? lookupContextTokens(model) ?? configContextTokens;
     const total = resolveFreshSessionTotalTokens(row);
 

src/commands/status.summary.ts

@@ -9,7 +9,11 @@ import {
   resolveStorePath,
   type SessionEntry,
 } from "../config/sessions.js";
-import { classifySessionKey, listAgentsForGateway } from "../gateway/session-utils.js";
+import {
+  classifySessionKey,
+  listAgentsForGateway,
+  resolveSessionModelRef,
+} from "../gateway/session-utils.js";
 import { buildChannelSummary } from "../infra/channel-summary.js";
 import { resolveHeartbeatSummaryForAgent } from "../infra/heartbeat-runner.js";
 import { peekSystemEvents } from "../infra/system-events.js";
@@ -125,7 +129,8 @@ export async function getStatusSummary(
       .map(([key, entry]) => {
         const updatedAt = entry?.updatedAt ?? null;
         const age = updatedAt ? now - updatedAt : null;
-        const model = entry?.model ?? configModel ?? null;
+        const resolvedModel = resolveSessionModelRef(cfg, entry, opts.agentIdOverride);
+        const model = resolvedModel.model ?? configModel ?? null;
         const contextTokens =
           entry?.contextTokens ?? lookupContextTokens(model) ?? configContextTokens ?? null;
         const total = resolveFreshSessionTotalTokens(entry);