fix(api): validate request bodies with Zod in 4 routes — restores the t06 gate (#9779)

The release-green verdict (#9737) lists check:route-validation:t06 as a HARD
failure and it is STILL red on the current tip: four routes call
request.json() and hand-roll `typeof x === "string"` checks instead of using
Zod, which Hard Rule #7 requires and the gate enforces (it scans source and
has no allowlist).

- src/app/api/plugins/marketplace/install (#9445): InstallBodySchema; the
  400 'Missing or invalid name field' response is preserved verbatim.
- src/app/api/services/dario/admin/accounts (#8523): DeleteAccountBodySchema
  for the optional { alias } DELETE body; query-param path untouched.
- src/app/api/services/dario/admin/login-start (#8523): LoginStartBodySchema;
  trimming now happens in the schema, so the forward body is unchanged.
- src/app/api/services/dario/admin/import-from-omniroute (#8523):
  ImportBodySchema for connectionId/alias; invalid shapes fall back to the
  same 'connectionId is required' 400 as before.

All four keep their exact status codes and messages — this is a validation
mechanism swap, not a contract change (plugins route suite still 33/33).

Adds tests/unit/route-body-validation-t06.test.ts, which runs the gate's own
rule inside the unit suite so the next such route fails on ITS OWN PR instead
of surfacing weeks later in a base-red sweep. Guard verified by mutation:
renaming .safeParse( in one route makes it fail (1 fail), restored from a
pre-probe copy.

Gates: route-validation:t06, file-size, test-discovery, mutation-test-coverage,
dead-code exit 0; typecheck:core clean; eslint clean.

Refs #9737

Co-authored-by: diegosouzapw <diegosouzapw@users.noreply.github.com>

src/app/api/plugins/marketplace/install/route.ts

@@ -1,9 +1,14 @@
 import { NextRequest, NextResponse } from "next/server";
+import { z } from "zod";
 import { CORS_HEADERS, handleCorsOptions } from "@/shared/utils/cors";
 import { buildErrorBody } from "@omniroute/open-sse/utils/error";
 import { installMarketplacePlugin } from "@/lib/plugins/marketplace";
 import { requireManagementAuth } from "@/lib/api/requireManagementAuth";
 
+const InstallBodySchema = z.object({
+  name: z.string().trim().min(1),
+});
+
 export async function OPTIONS() {
   return handleCorsOptions();
 }
@@ -15,15 +20,14 @@ export async function POST(request: NextRequest) {
   const authError = await requireManagementAuth(request);
   if (authError) return authError;
   try {
-    const body = await request.json();
-    const { name } = body as { name?: string };
-    if (!name || typeof name !== "string") {
+    const parsed = InstallBodySchema.safeParse(await request.json());
+    if (!parsed.success) {
       return NextResponse.json(buildErrorBody(400, "Missing or invalid 'name' field"), {
         status: 400,
         headers: CORS_HEADERS,
       });
     }
-    const result = await installMarketplacePlugin(name);
+    const result = await installMarketplacePlugin(parsed.data.name);
     return NextResponse.json(result, { status: 201, headers: CORS_HEADERS });
   } catch (err: unknown) {
     const msg = err instanceof Error ? err.message : "Failed to install marketplace plugin";

src/app/api/services/dario/admin/accounts/route.ts

@@ -11,9 +11,15 @@
  * and never reaches the browser.
  */
 
+import { z } from "zod";
+
 import { forwardToDarioAdmin, requireAdminAuth } from "../_lib";
 import { createErrorResponse } from "@/lib/api/errorResponse";
 
+const DeleteAccountBodySchema = z.object({
+  alias: z.string().trim().min(1).optional(),
+});
+
 export async function GET(request: Request): Promise<Response> {
   const authResponse = await requireAdminAuth(request);
   if (authResponse) return authResponse;
@@ -29,9 +35,9 @@ export async function DELETE(request: Request): Promise<Response> {
 
   if (!alias && request.body !== null) {
     try {
-      const parsed = await request.json();
-      if (parsed && typeof parsed === "object" && typeof (parsed as { alias?: unknown }).alias === "string") {
-        alias = (parsed as { alias: string }).alias.trim();
+      const parsed = DeleteAccountBodySchema.safeParse(await request.json());
+      if (parsed.success && parsed.data.alias) {
+        alias = parsed.data.alias;
       }
     } catch {
       /* fall through to the missing-alias error below */

src/app/api/services/dario/admin/import-from-omniroute/route.ts

@@ -28,6 +28,7 @@
  * pickup, rather than relying on any undocumented hot-reload behavior.
  */
 
+import { z } from "zod";
 import { NextResponse } from "next/server";
 import fs from "node:fs";
 import path from "node:path";
@@ -39,6 +40,11 @@ import { getDarioHomeDir } from "@/lib/services/installers/dario";
 import { createErrorResponse } from "@/lib/api/errorResponse";
 import { sanitizeErrorMessage } from "@omniroute/open-sse/utils/error";
 
+const ImportBodySchema = z.object({
+  connectionId: z.string().trim().min(1).optional(),
+  alias: z.string().trim().min(1).optional(),
+});
+
 const ALIAS_PATTERN = /^[A-Za-z0-9][A-Za-z0-9_\-.]{0,63}$/;
 
 function safeAliasFromSource(email: string | null | undefined, connectionId: string): string {
@@ -82,15 +88,16 @@ export async function POST(request: Request): Promise<Response> {
   const authResponse = await requireAdminAuth(request);
   if (authResponse) return authResponse;
 
-  let body: unknown;
+  let raw: unknown;
   try {
-    body = await request.json();
+    raw = await request.json();
   } catch {
     return createErrorResponse({ status: 400, message: "Invalid JSON body" });
   }
 
-  const b = (body || {}) as Record<string, unknown>;
-  const connectionId = typeof b.connectionId === "string" ? b.connectionId : null;
+  const parsed = ImportBodySchema.safeParse(raw ?? {});
+  const b = parsed.success ? parsed.data : {};
+  const connectionId = b.connectionId ?? null;
   if (!connectionId) {
     return createErrorResponse({ status: 400, message: "connectionId is required" });
   }
@@ -112,10 +119,7 @@ export async function POST(request: Request): Promise<Response> {
     });
   }
 
-  let alias =
-    typeof b.alias === "string" && b.alias.trim()
-      ? b.alias.trim()
-      : safeAliasFromSource(conn.email as string | null, connectionId);
+  let alias = b.alias || safeAliasFromSource(conn.email as string | null, connectionId);
   if (!ALIAS_PATTERN.test(alias)) {
     alias = safeAliasFromSource(conn.email as string | null, connectionId);
   }

src/app/api/services/dario/admin/login-start/route.ts

@@ -8,23 +8,29 @@
  * posts the displayed code to /login-complete.
  */
 
+import { z } from "zod";
 import { forwardToDarioAdmin, requireAdminAuth } from "../_lib";
 import { createErrorResponse } from "@/lib/api/errorResponse";
 
+const LoginStartBodySchema = z.object({
+  alias: z.string().trim().min(1).optional(),
+});
+type LoginStartBody = z.infer<typeof LoginStartBodySchema>;
+
 export async function POST(request: Request): Promise<Response> {
   const authResponse = await requireAdminAuth(request);
   if (authResponse) return authResponse;
 
-  let body: { alias?: string } = {};
+  let body: LoginStartBody = {};
   try {
     if (request.body !== null) {
-      const parsed = await request.json();
-      if (parsed && typeof parsed === "object") body = parsed as { alias?: string };
+      const parsed = LoginStartBodySchema.safeParse(await request.json());
+      if (parsed.success) body = parsed.data;
     }
   } catch {
     return createErrorResponse({ status: 400, message: "Invalid JSON body" });
   }
 
-  const forwardBody = typeof body.alias === "string" && body.alias.trim() ? { alias: body.alias.trim() } : {};
+  const forwardBody = body.alias ? { alias: body.alias } : {};
   return forwardToDarioAdmin({ method: "POST", path: "/admin/login/start", body: forwardBody });
 }