diff --git a/.changeset/quiet-connection-setup.md b/.changeset/quiet-connection-setup.md
new file mode 100644
index 0000000000..9d75373928
--- /dev/null
+++ b/.changeset/quiet-connection-setup.md
@@ -0,0 +1,5 @@
+---
+"executor": patch
+---
+
+Accept Slack bot and user OAuth token envelopes during sign-in and token refresh.
diff --git a/e2e/scenarios/connection-setup-ux.test.ts b/e2e/scenarios/connection-setup-ux.test.ts
new file mode 100644
index 0000000000..8158a9edbd
--- /dev/null
+++ b/e2e/scenarios/connection-setup-ux.test.ts
@@ -0,0 +1,137 @@
+import { randomBytes } from "node:crypto";
+import { expect } from "@effect/vitest";
+import { Effect } from "effect";
+import { composePluginApi } from "@executor-js/api/server";
+import { connectEmulator } from "@executor-js/emulate";
+import { openApiHttpPlugin } from "@executor-js/plugin-openapi/api";
+import { IntegrationSlug, OAuthClientSlug } from "@executor-js/sdk/shared";
+import { variable } from "@executor-js/sdk/http-auth";
+import { createEmulatorInstance } from "../src/emulator-instance";
+import { scenario } from "../src/scenario";
+import { Api, Browser, Target } from "../src/services";
+import { visit } from "../src/surfaces/browser";
+
+const api = composePluginApi([openApiHttpPlugin()] as const);
+// Each journey has its own real provider state, OAuth app, user and integration.
+const fixture = Effect.gen(function* () {
+  const target = yield* Target;
+  const browser = yield* Browser;
+  const { client: makeClient } = yield* Api;
+  const identity = yield* target.newIdentity();
+  const client = yield* makeClient(api, identity);
+  const slug = IntegrationSlug.make(`setup-${randomBytes(4).toString("hex")}`);
+  const app = OAuthClientSlug.make(`${slug}-app`);
+  const baseUrl = yield* createEmulatorInstance("slack", "connection-setup");
+  const emulator = yield* Effect.promise(() => connectEmulator({ baseUrl }));
+  const credential = yield* Effect.promise(() =>
+    emulator.credentials.mint({
+      type: "oauth-authorization-code",
+      redirect_uris: [new URL("/api/oauth/callback", target.baseUrl).toString()],
+    }),
+  );
+  const {
+    client_id: clientId,
+    client_secret: clientSecret,
+    authorization_url: authorizationUrl,
+    token_url: tokenUrl,
+  } = credential;
+  if (!clientId || !clientSecret || !authorizationUrl || !tokenUrl) {
+    return yield* Effect.die("Slack emulator did not mint an OAuth app");
+  }
+  yield* Effect.addFinalizer(() =>
+    Effect.gen(function* () {
+      const connections = yield* client.connections.list({ query: { integration: slug } });
+      for (const connection of connections) {
+        yield* client.connections
+          .remove({
+            params: {
+              owner: connection.owner,
+              integration: slug,
+              name: connection.name,
+            },
+          })
+          .pipe(Effect.ignore);
+      }
+      yield* client.oauth
+        .removeClient({ params: { slug: app }, payload: { owner: "org" } })
+        .pipe(Effect.ignore);
+      yield* client.openapi.removeSpec({ params: { slug } }).pipe(Effect.ignore);
+    }).pipe(Effect.ignore),
+  );
+  yield* client.openapi.addSpec({
+    payload: {
+      slug,
+      name: "Team chat",
+      baseUrl: "https://slack.com",
+      displayDomain: "slack.com",
+      spec: {
+        kind: "blob",
+        value: JSON.stringify({
+          openapi: "3.0.3",
+          info: { title: "Team chat", version: "1" },
+          // No API operations: only the isolated emulator receives OAuth traffic.
+          servers: [{ url: "https://slack.com" }],
+          paths: {},
+        }),
+      },
+      authenticationTemplate: [
+        {
+          slug: "token",
+          type: "apiKey",
+          headers: { Authorization: ["Bearer ", variable("token")] },
+        },
+        { slug: "oauth", kind: "oauth2", authorizationUrl, tokenUrl, scopes: ["users:read"] },
+      ],
+    },
+  });
+  yield* client.oauth.createClient({
+    payload: {
+      slug: app,
+      owner: "org",
+      grant: "authorization_code",
+      clientId,
+      clientSecret,
+      authorizationUrl,
+      tokenUrl,
+      originIntegration: slug,
+    },
+  });
+  return { target, browser, identity, client, slug, emulator };
+});
+
+scenario(
+  "Slack OAuth · provider consent saves a connection",
+  {},
+  Effect.scoped(
+    Effect.gen(function* () {
+      const { browser, identity, slug, client, emulator } = yield* fixture;
+      yield* browser.session(identity, async ({ page, step }) => {
+        await step("Sign in with a provider account without naming the connection", async () => {
+          await visit(page, `/integrations/${slug}?addAccount=1`);
+          await page.getByRole("tab", { name: "OAuth2", exact: true }).click();
+          const opened = page.waitForEvent("popup");
+          await page.getByRole("button", { name: "Connect with OAuth", exact: true }).click();
+          const popup = await opened;
+          await popup.waitForURL(/oauth\/v2\/authorize/);
+          // The hosted emulator renders a root-relative form action. Rebase only
+          // that provider transport onto this run's isolated instance.
+          await popup.route("https://emulators.dev/oauth/v2/authorize/callback", (route) =>
+            route.continue({ url: `${emulator.baseUrl}/oauth/v2/authorize/callback` }),
+          );
+          await popup.getByRole("button", { name: /admin/ }).click();
+          await page
+            .getByRole("heading", { name: /Add connection/ })
+            .waitFor({ state: "hidden", timeout: 30_000 });
+        });
+      });
+      const connections = yield* client.connections.list({ query: { integration: slug } });
+      expect(connections, "the completed callback persists the new account").toHaveLength(1);
+      expect(connections[0]?.name).toBeTruthy();
+      const ledger = yield* Effect.promise(() => emulator.ledger.list());
+      expect(
+        ledger.some((entry) => entry.method === "POST" && entry.path.includes("oauth.v2.access")),
+        "the real provider exchanged an authorization code",
+      ).toBe(true);
+    }),
+  ),
+);
diff --git a/packages/core/sdk/src/oauth-helpers.test.ts b/packages/core/sdk/src/oauth-helpers.test.ts
index d94e8c34ad..92bc623d06 100644
--- a/packages/core/sdk/src/oauth-helpers.test.ts
+++ b/packages/core/sdk/src/oauth-helpers.test.ts
@@ -621,6 +621,7 @@ describe("exchangeAuthorizationCode", () => {
   it.effect("uses nested granted scopes for Slack-style user token responses", () =>
     withTokenEndpoint(
       tokenResponse({
+        ok: true,
         access_token: "xoxp-user-token",
         token_type: "Bearer",
         scope: "",
@@ -1838,3 +1839,155 @@ describe("OAuth2Error tagging", () => {
     });
   });
 });
+
+// Slack labels bearer credentials by actor type. The same envelope is used
+// during authorization-code exchange and refresh-token rotation.
+describe("Provider token envelopes", () => {
+  const grants = [
+    {
+      label: "standard bearer response with ok metadata",
+      body: {
+        ok: true,
+        access_token: "provider-token",
+        token_type: "Bearer",
+        scope: "scope,with-comma other.scope",
+      },
+      expected: {
+        access_token: "provider-token",
+        token_type: "bearer",
+        scope: "scope,with-comma other.scope",
+      },
+    },
+    {
+      // https://docs.slack.dev/reference/methods/oauth.v2.access/
+      // A single response can contain two distinct accounts and refresh tokens.
+      label: "Slack bot and user response",
+      body: {
+        ok: true,
+        access_token: "bot-token",
+        token_type: "bot",
+        scope: "commands,incoming-webhook",
+        expires_in: 43200,
+        refresh_token: "bot-refresh",
+        authed_user: {
+          access_token: "user-token",
+          token_type: "user",
+          scope: "chat:write",
+          expires_in: 43200,
+          refresh_token: "user-refresh",
+        },
+      },
+      expected: {
+        access_token: "bot-token",
+        token_type: "bearer",
+        scope: "commands incoming-webhook",
+        expires_in: 43200,
+        refresh_token: "bot-refresh",
+      },
+    },
+    {
+      label: "bot",
+      body: {
+        ok: true,
+        access_token: "bot-token",
+        token_type: "bot",
+        scope: "channels:read,chat:write",
+        refresh_token: "bot-refresh",
+        expires_in: 3600,
+      },
+      expected: {
+        access_token: "bot-token",
+        token_type: "bearer",
+        scope: "channels:read chat:write",
+        refresh_token: "bot-refresh",
+        expires_in: 3600,
+      },
+    },
+    {
+      label: "user",
+      body: {
+        ok: true,
+        access_token: "user-token",
+        token_type: "user",
+        scope: "users:read,users:read.email",
+        refresh_token: "user-refresh",
+        expires_in: 3600,
+      },
+      expected: {
+        access_token: "user-token",
+        token_type: "bearer",
+        scope: "users:read users:read.email",
+        refresh_token: "user-refresh",
+        expires_in: 3600,
+      },
+    },
+    {
+      label: "nested user",
+      body: {
+        ok: true,
+        authed_user: {
+          access_token: "nested-user-token",
+          token_type: "user",
+          scope: "users:read,chat:write",
+          refresh_token: "nested-refresh",
+          expires_in: 3600,
+        },
+      },
+      expected: {
+        access_token: "nested-user-token",
+        token_type: "bearer",
+        scope: "users:read chat:write",
+        refresh_token: "nested-refresh",
+        expires_in: 3600,
+      },
+    },
+  ];
+  for (const grant of grants) {
+    it.effect(`exchanges a ${grant.label} grant`, () =>
+      withTokenEndpoint(tokenResponse(grant.body), ({ tokenUrl }) =>
+        Effect.gen(function* () {
+          const result = yield* exchangeAuthorizationCode({
+            tokenUrl,
+            clientId: "cid",
+            clientSecret: "secret",
+            redirectUrl: "https://app.example/callback",
+            codeVerifier: "verifier",
+            code: "code",
+          });
+          expect(result).toMatchObject(grant.expected);
+        }),
+      ),
+    );
+    it.effect(`refreshes a ${grant.label} grant`, () =>
+      withTokenEndpoint(tokenResponse(grant.body), ({ tokenUrl }) =>
+        Effect.gen(function* () {
+          const result = yield* refreshAccessToken({
+            tokenUrl,
+            clientId: "cid",
+            clientSecret: "secret",
+            refreshToken: "old-refresh",
+          });
+          expect(result).toMatchObject(grant.expected);
+        }),
+      ),
+    );
+  }
+  it.effect("still rejects unsupported token types in an otherwise successful envelope", () =>
+    withTokenEndpoint(
+      tokenResponse({ ok: true, access_token: "token", token_type: "mac" }),
+      ({ tokenUrl }) =>
+        Effect.gen(function* () {
+          const exit = yield* Effect.exit(
+            exchangeAuthorizationCode({
+              tokenUrl,
+              clientId: "cid",
+              redirectUrl: "https://app.example/callback",
+              codeVerifier: "verifier",
+              code: "code",
+            }),
+          );
+          expect(Exit.isFailure(exit)).toBe(true);
+        }),
+    ),
+  );
+});
diff --git a/packages/core/sdk/src/oauth-helpers.ts b/packages/core/sdk/src/oauth-helpers.ts
index c6e3209fe7..b8b11714c2 100644
--- a/packages/core/sdk/src/oauth-helpers.ts
+++ b/packages/core/sdk/src/oauth-helpers.ts
@@ -1117,16 +1117,74 @@ const stripIdToken = async (response: Response): Promise<StrippedTokenResponse>
   };
 };
 
+const SlackGrant = Schema.Struct({
+  access_token: Schema.optional(Schema.String),
+  token_type: Schema.optional(Schema.Literals(["bot", "user", "Bearer", "bearer"])),
+  refresh_token: Schema.optional(Schema.String),
+  expires_in: Schema.optional(Schema.Number),
+  scope: Schema.optional(Schema.String),
+});
+const decodeSlackEnvelope = Schema.decodeUnknownOption(
+  Schema.Struct({
+    ...SlackGrant.fields,
+    ok: Schema.Literal(true),
+    authed_user: Schema.optional(SlackGrant),
+  }),
+);
+
+/** Slack's `bot` and `user` values identify the account, not an HTTP auth
+ * scheme. Project its successful envelope to an RFC 6749 bearer grant before
+ * oauth4webapi validates it. User-only grants may live entirely in authed_user;
+ * never replace a populated top-level grant with another account's grant. */
+const normalizeSlackTokenEnvelope = async (response: Response): Promise<Response> => {
+  const decoded = decodeSlackEnvelope(await safeJsonFromResponse(response));
+  if (Option.isNone(decoded)) return response;
+  const envelope = decoded.value;
+  const user = envelope.authed_user;
+  const grant =
+    user?.access_token !== undefined &&
+    (envelope.access_token === undefined || !envelope.scope?.trim())
+      ? user
+      : envelope;
+  // Standard bearer responses may also contain `ok: true`. Preserve their
+  // scopes and provider metadata; only Slack's actor token types need adapting.
+  if (
+    grant.access_token === undefined ||
+    (grant.token_type !== "bot" && grant.token_type !== "user")
+  ) {
+    return response;
+  }
+  const scope = grant.scope
+    ?.split(/[\s,]+/)
+    .filter(Boolean)
+    .join(" ");
+  return new Response(
+    JSON.stringify({
+      access_token: grant.access_token,
+      token_type: "Bearer",
+      refresh_token: grant.refresh_token,
+      expires_in: grant.expires_in,
+      ...(scope ? { scope } : {}),
+    }),
+    {
+      status: response.status,
+      statusText: response.statusText,
+      headers: response.headers,
+    },
+  );
+};
+
 const processTokenEndpointResponse = async (
   as: oauth.AuthorizationServer,
   client: oauth.Client,
   response: Response,
 ): Promise<OAuth2TokenResponse> => {
   const stripped = await stripIdToken(response);
-  const providerUserGrant = await nestedAuthedUserGrant(stripped.response);
+  const normalizedResponse = await normalizeSlackTokenEnvelope(stripped.response);
+  const providerUserGrant = await nestedAuthedUserGrant(normalizedResponse);
   const parsed = tokenResponseFrom(
     as,
-    await oauth.processGenericTokenEndpointResponse(as, client, stripped.response),
+    await oauth.processGenericTokenEndpointResponse(as, client, normalizedResponse),
   );
   const token =
     parsed.scope === undefined && providerUserGrant !== undefined
@@ -1442,7 +1500,7 @@ export const refreshAccessToken = (
         const result = await oauth.processRefreshTokenResponse(
           as,
           client,
-          (await stripIdToken(response)).response,
+          await normalizeSlackTokenEnvelope((await stripIdToken(response)).response),
         );
         return tokenResponseFrom(as, result);
       },