diff --git a/src/agents/auth-profiles/oauth.fallback-to-main-agent.test.ts b/src/agents/auth-profiles/oauth.fallback-to-main-agent.test.ts
new file mode 100644
index 000000000..d37d1a8c3
--- /dev/null
+++ b/src/agents/auth-profiles/oauth.fallback-to-main-agent.test.ts
@@ -0,0 +1,164 @@
+import fs from "node:fs/promises";
+import path from "node:path";
+import os from "node:os";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { resolveApiKeyForProfile } from "./oauth.js";
+import { ensureAuthProfileStore } from "./store.js";
+import type { AuthProfileStore } from "./types.js";
+
+describe("resolveApiKeyForProfile fallback to main agent", () => {
+  const previousStateDir = process.env.CLAWDBOT_STATE_DIR;
+  const previousAgentDir = process.env.CLAWDBOT_AGENT_DIR;
+  const previousPiAgentDir = process.env.PI_CODING_AGENT_DIR;
+  let tmpDir: string;
+  let mainAgentDir: string;
+  let secondaryAgentDir: string;
+
+  beforeEach(async () => {
+    tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), "oauth-fallback-test-"));
+    mainAgentDir = path.join(tmpDir, "agents", "main", "agent");
+    secondaryAgentDir = path.join(tmpDir, "agents", "kids", "agent");
+    await fs.mkdir(mainAgentDir, { recursive: true });
+    await fs.mkdir(secondaryAgentDir, { recursive: true });
+
+    // Set environment variables so resolveClawdbotAgentDir() returns mainAgentDir
+    process.env.CLAWDBOT_STATE_DIR = tmpDir;
+    process.env.CLAWDBOT_AGENT_DIR = mainAgentDir;
+    process.env.PI_CODING_AGENT_DIR = mainAgentDir;
+  });
+
+  afterEach(async () => {
+    vi.unstubAllGlobals();
+
+    // Restore original environment
+    if (previousStateDir === undefined) delete process.env.CLAWDBOT_STATE_DIR;
+    else process.env.CLAWDBOT_STATE_DIR = previousStateDir;
+    if (previousAgentDir === undefined) delete process.env.CLAWDBOT_AGENT_DIR;
+    else process.env.CLAWDBOT_AGENT_DIR = previousAgentDir;
+    if (previousPiAgentDir === undefined) delete process.env.PI_CODING_AGENT_DIR;
+    else process.env.PI_CODING_AGENT_DIR = previousPiAgentDir;
+
+    await fs.rm(tmpDir, { recursive: true, force: true });
+  });
+
+  it("falls back to main agent credentials when secondary agent token is expired and refresh fails", async () => {
+    const profileId = "anthropic:claude-cli";
+    const now = Date.now();
+    const expiredTime = now - 60 * 60 * 1000; // 1 hour ago
+    const freshTime = now + 60 * 60 * 1000; // 1 hour from now
+
+    // Write expired credentials for secondary agent
+    const secondaryStore: AuthProfileStore = {
+      version: 1,
+      profiles: {
+        [profileId]: {
+          type: "oauth",
+          provider: "anthropic",
+          access: "expired-access-token",
+          refresh: "expired-refresh-token",
+          expires: expiredTime,
+        },
+      },
+    };
+    await fs.writeFile(
+      path.join(secondaryAgentDir, "auth-profiles.json"),
+      JSON.stringify(secondaryStore),
+    );
+
+    // Write fresh credentials for main agent
+    const mainStore: AuthProfileStore = {
+      version: 1,
+      profiles: {
+        [profileId]: {
+          type: "oauth",
+          provider: "anthropic",
+          access: "fresh-access-token",
+          refresh: "fresh-refresh-token",
+          expires: freshTime,
+        },
+      },
+    };
+    await fs.writeFile(path.join(mainAgentDir, "auth-profiles.json"), JSON.stringify(mainStore));
+
+    // Mock fetch to simulate OAuth refresh failure
+    const fetchSpy = vi.fn(async () => {
+      return new Response(JSON.stringify({ error: "invalid_grant" }), {
+        status: 400,
+        headers: { "Content-Type": "application/json" },
+      });
+    });
+    vi.stubGlobal("fetch", fetchSpy);
+
+    // Load the secondary agent's store (will merge with main agent's store)
+    const loadedSecondaryStore = ensureAuthProfileStore(secondaryAgentDir);
+
+    // Call resolveApiKeyForProfile with the secondary agent's expired credentials
+    // This should:
+    // 1. Try to refresh the expired token (fails due to mocked fetch)
+    // 2. Fall back to main agent's fresh credentials
+    // 3. Copy those credentials to the secondary agent
+    const result = await resolveApiKeyForProfile({
+      store: loadedSecondaryStore,
+      profileId,
+      agentDir: secondaryAgentDir,
+    });
+
+    expect(result).not.toBeNull();
+    expect(result?.apiKey).toBe("fresh-access-token");
+    expect(result?.provider).toBe("anthropic");
+
+    // Verify the credentials were copied to the secondary agent
+    const updatedSecondaryStore = JSON.parse(
+      await fs.readFile(path.join(secondaryAgentDir, "auth-profiles.json"), "utf8"),
+    ) as AuthProfileStore;
+    expect(updatedSecondaryStore.profiles[profileId]).toMatchObject({
+      access: "fresh-access-token",
+      expires: freshTime,
+    });
+  });
+
+  it("throws error when both secondary and main agent credentials are expired", async () => {
+    const profileId = "anthropic:claude-cli";
+    const now = Date.now();
+    const expiredTime = now - 60 * 60 * 1000; // 1 hour ago
+
+    // Write expired credentials for both agents
+    const expiredStore: AuthProfileStore = {
+      version: 1,
+      profiles: {
+        [profileId]: {
+          type: "oauth",
+          provider: "anthropic",
+          access: "expired-access-token",
+          refresh: "expired-refresh-token",
+          expires: expiredTime,
+        },
+      },
+    };
+    await fs.writeFile(
+      path.join(secondaryAgentDir, "auth-profiles.json"),
+      JSON.stringify(expiredStore),
+    );
+    await fs.writeFile(path.join(mainAgentDir, "auth-profiles.json"), JSON.stringify(expiredStore));
+
+    // Mock fetch to simulate OAuth refresh failure
+    const fetchSpy = vi.fn(async () => {
+      return new Response(JSON.stringify({ error: "invalid_grant" }), {
+        status: 400,
+        headers: { "Content-Type": "application/json" },
+      });
+    });
+    vi.stubGlobal("fetch", fetchSpy);
+
+    const loadedSecondaryStore = ensureAuthProfileStore(secondaryAgentDir);
+
+    // Should throw because both agents have expired credentials
+    await expect(
+      resolveApiKeyForProfile({
+        store: loadedSecondaryStore,
+        profileId,
+        agentDir: secondaryAgentDir,
+      }),
+    ).rejects.toThrow(/OAuth token refresh failed/);
+  });
+});
diff --git a/src/agents/auth-profiles/oauth.ts b/src/agents/auth-profiles/oauth.ts
index 4138cda94..d7b3360de 100644
--- a/src/agents/auth-profiles/oauth.ts
+++ b/src/agents/auth-profiles/oauth.ts
@@ -4,7 +4,7 @@ import lockfile from "proper-lockfile";
 import type { ClawdbotConfig } from "../../config/config.js";
 import { refreshChutesTokens } from "../chutes-oauth.js";
 import { refreshQwenPortalCredentials } from "../../providers/qwen-portal-oauth.js";
-import { AUTH_STORE_LOCK_OPTIONS } from "./constants.js";
+import { AUTH_STORE_LOCK_OPTIONS, log } from "./constants.js";
 import { formatAuthDoctorHint } from "./doctor.js";
 import { ensureAuthStoreFile, resolveAuthStorePath } from "./paths.js";
 import { suggestOAuthProfileIdForLegacyDefault } from "./repair.js";
@@ -196,6 +196,32 @@ export async function resolveApiKeyForProfile(params: {
         // keep original error
       }
     }
+
+    // Fallback: if this is a secondary agent, try using the main agent's credentials
+    if (params.agentDir) {
+      try {
+        const mainStore = ensureAuthProfileStore(undefined); // main agent (no agentDir)
+        const mainCred = mainStore.profiles[profileId];
+        if (mainCred?.type === "oauth" && Date.now() < mainCred.expires) {
+          // Main agent has fresh credentials - copy them to this agent and use them
+          refreshedStore.profiles[profileId] = { ...mainCred };
+          saveAuthProfileStore(refreshedStore, params.agentDir);
+          log.info("inherited fresh OAuth credentials from main agent", {
+            profileId,
+            agentDir: params.agentDir,
+            expires: new Date(mainCred.expires).toISOString(),
+          });
+          return {
+            apiKey: buildOAuthApiKey(mainCred.provider, mainCred),
+            provider: mainCred.provider,
+            email: mainCred.email,
+          };
+        }
+      } catch {
+        // keep original error if main agent fallback also fails
+      }
+    }
+
     const message = error instanceof Error ? error.message : String(error);
     const hint = formatAuthDoctorHint({
       cfg,
diff --git a/ui/src/ui/app-gateway.ts b/ui/src/ui/app-gateway.ts
index d9a267a98..0df25bbdf 100644
--- a/ui/src/ui/app-gateway.ts
+++ b/ui/src/ui/app-gateway.ts
@@ -127,6 +127,12 @@ export function connectGateway(host: GatewayHost) {
       host.lastError = null;
       host.hello = hello;
       applySnapshot(host, hello);
+      // Reset orphaned chat run state from before disconnect.
+      // Any in-flight run's final event was lost during the disconnect window.
+      host.chatRunId = null;
+      (host as unknown as { chatStream: string | null }).chatStream = null;
+      (host as unknown as { chatStreamStartedAt: number | null }).chatStreamStartedAt = null;
+      resetToolStream(host as unknown as Parameters<typeof resetToolStream>[0]);
       void loadAssistantIdentity(host as unknown as ClawdbotApp);
       void loadAgents(host as unknown as ClawdbotApp);
       void loadNodes(host as unknown as ClawdbotApp, { quiet: true });