diff --git a/packages/connections/src/mcp-oauth-routes.test.ts b/packages/connections/src/mcp-oauth-routes.test.ts
index 58b26f532..4515d86e5 100644
--- a/packages/connections/src/mcp-oauth-routes.test.ts
+++ b/packages/connections/src/mcp-oauth-routes.test.ts
@@ -443,7 +443,7 @@ describe("MCP OAuth connect flow", () => {
     }
   });
 
-  test("an unknown slug with no url override is a 404", async () => {
+  test("an unknown slug with no url override redirects as an error", async () => {
     const hub = fakeHub();
     const routes = createMcpOAuthRoutes({
       hubUrl: "http://hub.test",
@@ -453,8 +453,13 @@ describe("MCP OAuth connect flow", () => {
       apiCall: hub.apiCall,
     });
     const app = mountAs(routes);
-    const response = await app.request("/not-a-preset/start");
-    expect(response.status).toBe(404);
+    const response = await app.request("/not-a-preset/start", {
+      redirect: "manual",
+    });
+    expect(response.status).toBe(302);
+    expect(response.headers.get("location")).toBe(
+      "/plugins?mcpOauth=not-a-preset&outcome=error&code=not_found",
+    );
   });
 
   test("a preset that doesn't connect with OAuth is refused at start, not mid-dance", async () => {
@@ -470,8 +475,13 @@ describe("MCP OAuth connect flow", () => {
     // github-mcp is a token preset (GitHub offers no dynamic client
     // registration) and exa is keyless — neither has an OAuth dance.
     for (const slug of ["github-mcp", "exa"]) {
-      const response = await app.request(`/${slug}/start`);
-      expect(response.status).toBe(400);
+      const response = await app.request(`/${slug}/start`, {
+        redirect: "manual",
+      });
+      expect(response.status).toBe(302);
+      expect(response.headers.get("location")).toBe(
+        `/plugins?mcpOauth=${slug}&outcome=error&code=bad_request`,
+      );
     }
   });
 
diff --git a/packages/connections/src/mcp-oauth-routes.ts b/packages/connections/src/mcp-oauth-routes.ts
index 39ae0514c..ce5a29328 100644
--- a/packages/connections/src/mcp-oauth-routes.ts
+++ b/packages/connections/src/mcp-oauth-routes.ts
@@ -47,10 +47,6 @@ import {
   sanitizeReturnPath,
 } from "./oauth-routes";
 
-const ErrorEnvelope = (code: string, message: string) => ({
-  error: { code, message },
-});
-
 const OAUTH_STATE_TTL_MS = 10 * 60 * 1000;
 
 // One provider label for the whole MCP connect surface — the sealed
@@ -156,12 +152,13 @@ export function createMcpOAuthRoutes(
         returnPathAllowlist,
       );
       if (target === undefined) {
-        return c.json(
-          ErrorEnvelope(
-            "not_found",
-            `Unknown MCP server preset: "${slugParam}"`,
-          ),
-          404,
+        return c.redirect(
+          redirectPath(returnPath, {
+            mcpOauth: slugParam,
+            outcome: "error",
+            code: "not_found",
+          }),
+          302,
         );
       }
       const queryUrl = c.req.query("url");
@@ -173,12 +170,13 @@ export function createMcpOAuthRoutes(
         // A keyless or token preset has no OAuth dance to start — refuse
         // here rather than failing mid-dance at the provider (GitHub's
         // MCP server, for one, offers no dynamic client registration).
-        return c.json(
-          ErrorEnvelope(
-            "bad_request",
-            `${preset.displayName} doesn't connect with a sign-in here — connect it from Plugins instead.`,
-          ),
-          400,
+        return c.redirect(
+          redirectPath(returnPath, {
+            mcpOauth: preset.slug,
+            outcome: "error",
+            code: "bad_request",
+          }),
+          302,
         );
       }
 
diff --git a/packages/plugins-ui/src/index.ts b/packages/plugins-ui/src/index.ts
index 3c0781b36..04c7a9fc2 100644
--- a/packages/plugins-ui/src/index.ts
+++ b/packages/plugins-ui/src/index.ts
@@ -9,6 +9,8 @@ export { PluginConnectPanel } from "./plugin-connect-panel";
 export { McpServersSection } from "./mcp-servers-section";
 export { McpPresetCardsSection } from "./mcp-preset-cards";
 
+export { PLUGINS_STRINGS } from "./strings";
+
 export {
   McpServersApiError,
   listMcpServers,
diff --git a/packages/plugins-ui/src/mcp-preset-cards.tsx b/packages/plugins-ui/src/mcp-preset-cards.tsx
index 99a88d825..80e47b84f 100644
--- a/packages/plugins-ui/src/mcp-preset-cards.tsx
+++ b/packages/plugins-ui/src/mcp-preset-cards.tsx
@@ -15,11 +15,38 @@ import {
   type McpPreset,
 } from "./mcp-servers-api";
 import { PluginLogo } from "./plugin-logo";
+import { PLUGINS_STRINGS } from "./strings";
 
 function messageOf(cause: unknown): string {
   return cause instanceof Error ? cause.message : String(cause);
 }
 
+const MCP_OAUTH_ERROR_COPY: Readonly<Record<string, string>> = {
+  discovery_failed: "Couldn't reach that app's sign-in. Try connecting again.",
+  no_authorization_needed:
+    "That app didn't start a sign-in. Try connecting again.",
+  state_expired:
+    "The connection took too long or was already used. Try connecting again.",
+  state_mismatch: "The connection was interrupted. Try connecting again.",
+  exchange_failed: "That app didn't hand back a token. Try connecting again.",
+  connect_failed: "Couldn't finish connecting. Try connecting again.",
+  setup_failed:
+    "The sign-in worked, but storing the connection failed. Try connecting again.",
+  not_found: "That app isn't in this catalog.",
+  bad_request: "This app doesn't connect with a sign-in here.",
+};
+
+function mcpOauthReturnError(slug: string): string | null {
+  const params = new URLSearchParams(window.location.search);
+  if (params.get("mcpOauth") !== slug) return null;
+  if (params.get("outcome") !== "error") return null;
+  const code = params.get("code");
+  return (
+    (code !== null ? MCP_OAUTH_ERROR_COPY[code] : undefined) ??
+    "The connection did not finish. Try connecting again."
+  );
+}
+
 function McpPresetCard({
   tenantId,
   preset,
@@ -32,7 +59,9 @@ function McpPresetCard({
   readonly onChanged: (toolCount?: number) => void;
 }) {
   const [busy, setBusy] = useState(false);
-  const [error, setError] = useState<string | null>(null);
+  const [error, setError] = useState<string | null>(() =>
+    mcpOauthReturnError(preset.slug),
+  );
   const [tokenFieldOpen, setTokenFieldOpen] = useState(false);
   const [token, setToken] = useState("");
 
@@ -72,7 +101,7 @@ function McpPresetCard({
         toast(`${preset.displayName} disconnected.`);
         onChanged();
       })
-      .catch(() => setError("Couldn't disconnect — try again."))
+      .catch(() => setError(PLUGINS_STRINGS.disconnectError))
       .finally(() => setBusy(false));
   }
 
diff --git a/packages/plugins-ui/src/mcp-servers-section.tsx b/packages/plugins-ui/src/mcp-servers-section.tsx
index d6f6827c2..f1f385e9a 100644
--- a/packages/plugins-ui/src/mcp-servers-section.tsx
+++ b/packages/plugins-ui/src/mcp-servers-section.tsx
@@ -18,6 +18,7 @@ import {
   listMcpServers,
   type McpServer,
 } from "./mcp-servers-api";
+import { PLUGINS_STRINGS } from "./strings";
 
 function messageOf(cause: unknown): string {
   return cause instanceof Error ? cause.message : String(cause);
@@ -43,7 +44,7 @@ function ConnectedMcpServerRow({
         toast(`${server.name} disconnected.`);
         onChanged();
       })
-      .catch(() => setError("Couldn't disconnect — try again."))
+      .catch(() => setError(PLUGINS_STRINGS.disconnectError))
       .finally(() => setBusy(false));
   }
 
diff --git a/packages/plugins-ui/src/plugin-connect-panel.tsx b/packages/plugins-ui/src/plugin-connect-panel.tsx
index 68320ab20..13b112b4d 100644
--- a/packages/plugins-ui/src/plugin-connect-panel.tsx
+++ b/packages/plugins-ui/src/plugin-connect-panel.tsx
@@ -37,6 +37,7 @@ import type { ResolvedPlugin } from "@workbench/connections/plugins";
 import { useEffect, useState } from "react";
 
 import { pluginOutcome } from "./plugin-meta";
+import { PLUGINS_STRINGS } from "./strings";
 
 const PLUGINS_RETURN_PATH = "/plugins";
 
@@ -142,7 +143,7 @@ function ConnectedSummary({
         toast(`${plugin.descriptor.displayName} disconnected.`);
         onChanged();
       })
-      .catch(() => setError("Couldn't disconnect — try again."))
+      .catch(() => setError(PLUGINS_STRINGS.disconnectError))
       .finally(() => setBusy(false));
   }
 
diff --git a/packages/plugins-ui/src/plugins-gallery.tsx b/packages/plugins-ui/src/plugins-gallery.tsx
index 8b9e5ad7d..1650f80ec 100644
--- a/packages/plugins-ui/src/plugins-gallery.tsx
+++ b/packages/plugins-ui/src/plugins-gallery.tsx
@@ -236,14 +236,7 @@ export function PluginsGallery({
           <div className="flex flex-col gap-4 pt-3">
             {active === "plugins" ? (
               <>
-                <div>
-                  <h1 className="text-xl font-extrabold">Plugins</h1>
-                  <p className="mt-1 max-w-[65ch] text-sm text-muted-foreground">
-                    A directory to scan, not tiles to admire — one dense row per
-                    connector, grouped by what it does. Click a row's name for
-                    the full page.
-                  </p>
-                </div>
+                <h1 className="text-xl font-extrabold">Plugins</h1>
                 <McpPresetCardsSection tenantId={tenantId} query={query} />
                 <McpServersSection tenantId={tenantId} />
                 <PluginsTabPanel
diff --git a/packages/plugins-ui/src/strings.ts b/packages/plugins-ui/src/strings.ts
new file mode 100644
index 000000000..d5bef00ea
--- /dev/null
+++ b/packages/plugins-ui/src/strings.ts
@@ -0,0 +1,6 @@
+// Every user-facing word the plugins surface prints, in one place. Nothing
+// in the plugins-ui/* components inlines its own copy; it imports from here.
+
+export const PLUGINS_STRINGS = {
+  disconnectError: "Couldn't disconnect — try again.",
+} as const;
diff --git a/packages/plugins-ui/test/mcp-preset-cards.test.tsx b/packages/plugins-ui/test/mcp-preset-cards.test.tsx
index 981ee6f83..52f78222f 100644
--- a/packages/plugins-ui/test/mcp-preset-cards.test.tsx
+++ b/packages/plugins-ui/test/mcp-preset-cards.test.tsx
@@ -16,6 +16,7 @@ const realFetch = globalThis.fetch;
 let mountedRoots: Root[] = [];
 afterEach(() => {
   globalThis.fetch = realFetch;
+  window.history.replaceState(null, "", "https://workbench.test/");
   for (const root of mountedRoots) act(() => root.unmount());
   mountedRoots = [];
 });
@@ -116,6 +117,92 @@ describe("McpPresetCardsSection", () => {
     expect(connectGranola?.textContent?.trim()).toBe("Connect");
   });
 
+  test("Connect Granola navigates to /start via location href, never fetch", async () => {
+    const calls: string[] = [];
+    globalThis.fetch = (async (url: string) => {
+      calls.push(String(url));
+      return new Response(JSON.stringify({ data: PRESETS }));
+    }) as unknown as typeof fetch;
+
+    const assigned: string[] = [];
+    const hrefDescriptor = Object.getOwnPropertyDescriptor(
+      window.location,
+      "href",
+    );
+    Object.defineProperty(window.location, "href", {
+      configurable: true,
+      get() {
+        return (
+          hrefDescriptor?.get?.call(window.location) ??
+          "https://workbench.test/"
+        );
+      },
+      set(value: string) {
+        assigned.push(value);
+      },
+    });
+
+    try {
+      const container = mountSection();
+      await settle();
+
+      const granolaCard = container.querySelector(
+        '[data-plugin-slug="granola"]',
+      ) as HTMLElement;
+      const connectButton = [...granolaCard.querySelectorAll("button")].find(
+        (button) => button.textContent?.includes("Connect"),
+      ) as HTMLButtonElement;
+
+      await act(async () => {
+        connectButton.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+        await new Promise((resolve) => setTimeout(resolve, 10));
+      });
+
+      expect(assigned).toEqual([
+        "/api/tenants/tenant_test/mcp-servers/oauth/granola/start",
+      ]);
+      expect(calls.some((url) => url.includes("/start"))).toBe(false);
+    } finally {
+      if (hrefDescriptor !== undefined) {
+        Object.defineProperty(window.location, "href", hrefDescriptor);
+      } else {
+        delete (window.location as { href?: string }).href;
+      }
+    }
+  });
+
+  test("an OAuth error return surfaces a sentence on that preset row and leaves Connect as retry", async () => {
+    window.history.replaceState(
+      null,
+      "",
+      "/?mcpOauth=granola&outcome=error&code=discovery_failed",
+    );
+    globalThis.fetch = (async () =>
+      new Response(
+        JSON.stringify({ data: PRESETS }),
+      )) as unknown as typeof fetch;
+
+    const container = mountSection();
+    await settle();
+
+    const granolaCard = container.querySelector(
+      '[data-plugin-slug="granola"]',
+    ) as HTMLElement;
+    expect(granolaCard.textContent).toContain(
+      "Couldn't reach that app's sign-in. Try connecting again.",
+    );
+    expect(
+      granolaCard.querySelector('[aria-label="Connect Granola"]'),
+    ).not.toBeNull();
+
+    const exaCard = container.querySelector(
+      '[data-plugin-slug="exa"]',
+    ) as HTMLElement;
+    expect(exaCard.textContent).not.toContain(
+      "Couldn't reach that app's sign-in. Try connecting again.",
+    );
+  });
+
   test("Disconnect's accessible name includes the preset display name (CL-6794)", async () => {
     globalThis.fetch = (async () =>
       new Response(
diff --git a/packages/plugins-ui/test/plugin-connect-panel.test.tsx b/packages/plugins-ui/test/plugin-connect-panel.test.tsx
index 2f866faca..993541c3c 100644
--- a/packages/plugins-ui/test/plugin-connect-panel.test.tsx
+++ b/packages/plugins-ui/test/plugin-connect-panel.test.tsx
@@ -13,6 +13,7 @@ import type { ConnectorDescriptor } from "@workbench/connections/registry";
 import type { ResolvedPlugin } from "@workbench/connections/plugins";
 
 import { PluginConnectPanel } from "../src/plugin-connect-panel";
+import { PLUGINS_STRINGS } from "../src/strings";
 
 const realFetch = globalThis.fetch;
 let mountedRoots: Root[] = [];
@@ -169,7 +170,7 @@ describe("PluginConnectPanel", () => {
     });
     await settle();
 
-    expect(container.textContent).toContain("Couldn't disconnect");
+    expect(container.textContent).toContain(PLUGINS_STRINGS.disconnectError);
   });
 
   function githubDescriptor(): ConnectorDescriptor {
diff --git a/packages/plugins-ui/test/plugins-gallery.test.tsx b/packages/plugins-ui/test/plugins-gallery.test.tsx
index e47d7dd9e..88c1c6826 100644
--- a/packages/plugins-ui/test/plugins-gallery.test.tsx
+++ b/packages/plugins-ui/test/plugins-gallery.test.tsx
@@ -203,14 +203,11 @@ describe("PluginsGallery", () => {
     expect(container.textContent).toContain("Inherited");
   });
 
-  test("the plugins tab renders the list heading and directory sub copy (CL-6467)", () => {
+  test("the plugins tab renders the list heading", () => {
     const { container } = renderGallery();
 
     const heading = container.querySelector("h1");
     expect(heading?.textContent).toBe("Plugins");
-    expect(container.textContent).toContain(
-      "A directory to scan, not tiles to admire — one dense row per connector, grouped by what it does. Click a row's name for the full page.",
-    );
   });
 
   test("a plugin row's status caption is never hidden — it is a core column, not overflow (CL-6467)", () => {