fix: validate Slack credentials before enabling channels

docs/reference/commands.mdx

@@ -1411,6 +1411,7 @@ These flags toggle optional behaviors during onboarding; set them before running
 | `NEMOCLAW_DISABLE_OVERLAY_FIX` | `1` to enable | Skips the Docker overlay-fix step during sandbox build. For environments where the fix is incompatible. |
 | `NEMOCLAW_OVERLAY_SNAPSHOTTER` | snapshotter name | Selects the containerd overlay snapshotter for sandbox builds. Empty (default) preserves containerd's choice. |
 | `NEMOCLAW_SKIP_TELEGRAM_REACHABILITY` | `1` to enable | Skips the Telegram bot reachability probe during onboard (useful in restricted networks). |
+| `NEMOCLAW_SKIP_SLACK_AUTH_VALIDATION` | `1` to enable | Skips the live Slack `auth.test` and `apps.connections.open` credential probes during onboard and `channels add slack`. Use only in restricted networks or hermetic test environments; Slack token format checks still apply. |
 | `NEMOCLAW_CONFIG_ACCEPT_NEW_PATH` | `1` to enable | Accepts a new sandbox config path without an interactive prompt when the stored path differs from the discovered one. |
 | `NEMOCLAW_RESOURCE_PROFILE` | profile name or `default` | Selects a sandbox CPU/RAM resource profile from the blueprint during onboarding. `default` means no resource preference, so NemoClaw passes no OpenShell CPU or memory flags. Unknown names fail fast. |
 | `NEMOCLAW_CPU` | percentage or Kubernetes CPU quantity | Overrides the selected profile's CPU size passed to OpenShell `--cpu`. Percentages resolve against detected capacity. |

src/lib/actions/sandbox/policy-channel.ts

@@ -28,6 +28,7 @@ import { runOpenshell } from "../../adapters/openshell/runtime";
 import { shellQuote } from "../../runner";
 import { executeSandboxCommand, executeSandboxExecCommand } from "./process-recovery";
 import { rebuildSandbox } from "./rebuild";
+import { validateSlackChannelCredentials } from "./slack-channel-validation";
 import { printTelegramDirectMessageAllowlistWarning } from "./telegram-channel-bridge-verification";
 import {
   type ChannelDef,
@@ -824,6 +825,17 @@ export async function addSandboxChannel(
     await acquirePasteTokens(canonical, channel, acquired);
   }
 
+  if (canonical === "slack") {
+    const validation = validateSlackChannelCredentials(channel, acquired);
+    if (!validation.ok) {
+      console.error(`  ${validation.message}`);
+      process.exit(1);
+    }
+    if (validation.message) {
+      console.log(`  ${YW}⚠${R} ${validation.message}`);
+    }
+  }
+
   persistChannelTokens(acquired);
   // Push to the gateway and update the registry NOW so that answering
   // "rebuild later" (or running non-interactively) does not silently

src/lib/actions/sandbox/slack-channel-validation.ts

@@ -0,0 +1,57 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+import type { ChannelDef } from "../../sandbox/channels";
+import {
+  formatSlackValidationFailure,
+  validateSlackCredentials,
+} from "../../onboard/slack-validation";
+
+export type SlackChannelCredentialValidationResult =
+  | { ok: true; message?: string }
+  | { ok: false; message: string };
+
+function isAcquiredTokenFormatValid(channel: ChannelDef, envKey: string, token: string): boolean {
+  if (envKey === channel.envKey) return !channel.tokenFormat || channel.tokenFormat.test(token);
+  if (envKey === channel.appTokenEnvKey) {
+    return !channel.appTokenFormat || channel.appTokenFormat.test(token);
+  }
+  return false;
+}
+
+export function validateSlackChannelCredentials(
+  channel: ChannelDef,
+  acquired: Record<string, string>,
+): SlackChannelCredentialValidationResult {
+  if (!channel.envKey || !channel.appTokenEnvKey) {
+    return { ok: false, message: "Slack channel definition is missing required token keys." };
+  }
+
+  const botToken = acquired[channel.envKey];
+  const appToken = acquired[channel.appTokenEnvKey];
+  if (!botToken || !appToken) {
+    return { ok: false, message: "Slack requires both SLACK_BOT_TOKEN and SLACK_APP_TOKEN." };
+  }
+
+  for (const [envKey, token] of Object.entries(acquired)) {
+    if (!isAcquiredTokenFormatValid(channel, envKey, token)) {
+      const hint =
+        envKey === channel.appTokenEnvKey
+          ? channel.appTokenFormatHint || "Check the token and try again."
+          : channel.tokenFormatHint || "Check the token and try again.";
+      return { ok: false, message: `Invalid ${envKey} format. ${hint}` };
+    }
+  }
+
+  const validation = validateSlackCredentials({ botToken, appToken });
+  if (validation.ok) {
+    return validation.skipped && validation.message
+      ? { ok: true, message: validation.message }
+      : { ok: true };
+  }
+
+  return {
+    ok: false,
+    message: `Slack credential validation failed. ${formatSlackValidationFailure(validation)}`,
+  };
+}

src/lib/onboard.ts

@@ -552,12 +552,10 @@ import {
   type SandboxGpuConfig,
   type SandboxGpuFlag,
 } from "./onboard/sandbox-gpu-mode";
+import { filterSlackSelectionByValidation } from "./onboard/slack-validation";
 import type { SelectionDrift } from "./onboard/selection-drift";
 import { formatOnboardConfigSummary, formatSandboxBuildEstimateNote } from "./onboard/summary";
-import type {
-  ModelValidationResult,
-  ValidationFailureLike,
-} from "./onboard/types";
+import type { ModelValidationResult, ValidationFailureLike } from "./onboard/types";
 import type { ContainerRuntime } from "./platform";
 import { getChannelTokenKeys, listChannels } from "./sandbox/channels";
 import type { GatewayReuseState } from "./state/gateway";
@@ -5611,6 +5609,7 @@ async function setupMessagingChannels(
           if (reachability.skipped) found = found.filter((c) => c !== "telegram");
         }
       }
+      found = filterSlackSelectionByValidation(found, MESSAGING_CHANNELS);
     } else {
       note("  [non-interactive] No messaging tokens configured. Skipping.");
     }

src/lib/onboard/messaging-channel-setup.test.ts

@@ -6,6 +6,7 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { prompt, saveCredential } from "../credentials/store";
 import { KNOWN_CHANNELS } from "../sandbox/channels";
 import { setupSelectedMessagingChannels } from "./messaging-channel-setup";
+import { validateSlackCredentials } from "./slack-validation";
 
 vi.mock("../credentials/store", () => ({
   getCredential: vi.fn(() => null),
@@ -20,11 +21,18 @@ vi.mock("./host-qr-dispatch", () => ({
   dispatchHostQrLogin: vi.fn(),
 }));
 
+vi.mock("./slack-validation", () => ({
+  formatSlackValidationFailure: vi.fn((result: { message: string }) => result.message),
+  validateSlackCredentials: vi.fn(() => ({ ok: true })),
+}));
+
 const ORIGINAL_ENV = { ...process.env };
 
 describe("setupSelectedMessagingChannels", () => {
   beforeEach(() => {
     process.env = { ...ORIGINAL_ENV };
+    vi.clearAllMocks();
+    vi.mocked(validateSlackCredentials).mockReturnValue({ ok: true });
   });
 
   afterEach(() => {
@@ -121,4 +129,105 @@ describe("setupSelectedMessagingChannels", () => {
     expect(output).toContain("Slack channel IDs");
     expect(output).toContain("channel IDs saved");
   });
+
+  it("does not save prompted Slack credentials when Slack API rejects them", async () => {
+    delete process.env.SLACK_BOT_TOKEN;
+    delete process.env.SLACK_APP_TOKEN;
+    vi.mocked(prompt)
+      .mockResolvedValueOnce("xoxb-fake-bot-token")
+      .mockResolvedValueOnce("xapp-fake-app-token");
+    vi.mocked(validateSlackCredentials).mockReturnValueOnce({
+      ok: false,
+      kind: "rejected",
+      tokenKind: "app",
+      credential: "app",
+      error: "invalid_auth",
+      httpStatus: 200,
+      curlStatus: 0,
+      message: "Slack app token was rejected by Slack API: invalid_auth.",
+    });
+    const enabled = new Set(["slack"]);
+    const logs: string[] = [];
+    vi.spyOn(console, "log").mockImplementation((message = "") => {
+      logs.push(String(message));
+    });
+
+    await setupSelectedMessagingChannels(
+      ["slack"],
+      enabled,
+      [{ name: "slack", ...KNOWN_CHANNELS.slack }],
+    );
+
+    expect(enabled.has("slack")).toBe(false);
+    expect(saveCredential).not.toHaveBeenCalled();
+    expect(process.env.SLACK_BOT_TOKEN).toBeUndefined();
+    expect(process.env.SLACK_APP_TOKEN).toBeUndefined();
+    const output = logs.join("\n");
+    expect(output).toContain("Slack app token was rejected by Slack API");
+    expect(output).not.toContain("xoxb-fake-bot-token");
+    expect(output).not.toContain("xapp-fake-app-token");
+  });
+
+  it("does not save prompted Slack credentials when Slack API validation is indeterminate", async () => {
+    delete process.env.SLACK_BOT_TOKEN;
+    delete process.env.SLACK_APP_TOKEN;
+    vi.mocked(prompt)
+      .mockResolvedValueOnce("xoxb-timeout-bot-token")
+      .mockResolvedValueOnce("xapp-timeout-app-token");
+    vi.mocked(validateSlackCredentials).mockReturnValueOnce({
+      ok: false,
+      kind: "indeterminate",
+      tokenKind: "bot",
+      credential: "bot",
+      httpStatus: 0,
+      curlStatus: 28,
+      message: "Slack bot token could not be validated because Slack API was unreachable.",
+    });
+    const enabled = new Set(["slack"]);
+
+    await setupSelectedMessagingChannels(
+      ["slack"],
+      enabled,
+      [{ name: "slack", ...KNOWN_CHANNELS.slack }],
+    );
+
+    expect(enabled.has("slack")).toBe(false);
+    expect(saveCredential).not.toHaveBeenCalled();
+    expect(process.env.SLACK_BOT_TOKEN).toBeUndefined();
+    expect(process.env.SLACK_APP_TOKEN).toBeUndefined();
+  });
+
+  it("ignores existing Slack tokens that pass format but fail Slack API validation", async () => {
+    process.env.SLACK_BOT_TOKEN = "xoxb-existing-invalid";
+    process.env.SLACK_APP_TOKEN = "xapp-existing-valid";
+    vi.mocked(validateSlackCredentials).mockReturnValueOnce({
+      ok: false,
+      kind: "rejected",
+      tokenKind: "bot",
+      credential: "bot",
+      error: "token_revoked",
+      httpStatus: 200,
+      curlStatus: 0,
+      message: "Slack bot token was rejected by Slack API: token_revoked.",
+    });
+    const enabled = new Set(["slack"]);
+    const logs: string[] = [];
+    vi.spyOn(console, "log").mockImplementation((message = "") => {
+      logs.push(String(message));
+    });
+
+    await setupSelectedMessagingChannels(
+      ["slack"],
+      enabled,
+      [{ name: "slack", ...KNOWN_CHANNELS.slack }],
+    );
+
+    expect(enabled.has("slack")).toBe(false);
+    expect(prompt).not.toHaveBeenCalled();
+    expect(saveCredential).not.toHaveBeenCalled();
+    const output = logs.join("\n");
+    expect(output).toContain("Invalid existing slack token ignored");
+    expect(output).toContain("token_revoked");
+    expect(output).not.toContain("slack — already configured");
+  });
 });