diff --git a/README.md b/README.md
index 1ca493de..2cdcd5e9 100644
--- a/README.md
+++ b/README.md
@@ -78,10 +78,12 @@ from the [Releases](https://github.com/ApocDev/pyops/releases) page:
 - **macOS** — `.dmg`
 - **Windows** — the `-setup.exe` installer
 
-It still needs **Factorio + the Py mods** installed locally (it reads your recipe
-data via a data sync), and a fresh install starts empty — open **⚙ Settings › Game
-data** and run a sync on first launch, same as [from source](#setup) below. For how
-it's built and released, see [`docs/desktop.md`](docs/desktop.md).
+It still needs **Factorio** installed locally to read your recipe data via a data
+sync — PyOps is built for the **Py** mods (and Py-specific views like TURD only
+appear when that data is present), but it'll load whatever mod set you sync. A fresh
+install starts empty — open **⚙ Settings › Game data** and run a sync on first
+launch, same as [from source](#setup) below. For how it's built and released, see
+[`docs/desktop.md`](docs/desktop.md).
 
 ---
 
diff --git a/app/src/components/app-nav.tsx b/app/src/components/app-nav.tsx
index 5590d0d8..1857357a 100644
--- a/app/src/components/app-nav.tsx
+++ b/app/src/components/app-nav.tsx
@@ -6,9 +6,9 @@ import { BridgeIndicator } from "./bridge-indicator";
 import { HorizonMenu } from "./horizon-menu";
 import { LogisticsMenu } from "./logistics-menu";
 import { NavMobile } from "./nav-mobile";
-import { NAV_LINKS, SETTINGS_LINK } from "./nav-links";
+import { SETTINGS_LINK, visibleNavLinks } from "./nav-links";
 import { activeRunCount, subscribeRuns } from "../lib/chat-store";
-import { modDriftFn } from "../server/factorio";
+import { dataCapabilitiesFn, modDriftFn } from "../server/factorio";
 import { driftModal } from "../lib/drift-store";
 
 /** Persistent re-entry point for the data-sync modal: a small amber chip in the
@@ -54,6 +54,7 @@ const active = "!text-foreground border-b-2 border-primary bg-muted/30";
  * bar shows from `xl` up (desktop/Steam Deck); below that it collapses to a
  * hamburger drawer (NavMobile) so it never forces the page wider than the screen. */
 export function AppNav() {
+  const caps = useQuery({ queryKey: ["dataCapabilities"], queryFn: () => dataCapabilitiesFn() });
   return (
     <nav className="flex h-10 shrink-0 items-stretch border-b border-border bg-card font-mono">
       <Link to="/" className="flex items-center gap-2 px-3 font-bold text-primary">
@@ -65,7 +66,7 @@ export function AppNav() {
           overflow and scroll sideways (notably at the 1280 Steam Deck width), so the
           hamburger drawer takes over. */}
       <div className="hidden flex-1 items-stretch min-[1400px]:flex">
-        {NAV_LINKS.map(({ to, label, icon: Icon }) => (
+        {visibleNavLinks(caps.data).map(({ to, label, icon: Icon }) => (
           <Link key={to} to={to} className={item} activeProps={{ className: `${item} ${active}` }}>
             <Icon className="size-4" /> {label}
           </Link>
diff --git a/app/src/components/nav-links.ts b/app/src/components/nav-links.ts
index 9085f465..5c47201d 100644
--- a/app/src/components/nav-links.ts
+++ b/app/src/components/nav-links.ts
@@ -23,7 +23,18 @@ export type NavLinkTo =
   | "/tasks"
   | "/settings";
 
-export type NavLink = { to: NavLinkTo; label: string; icon: LucideIcon };
+/** Data-driven, mod-specific capabilities of the loaded dataset (see
+ * `dataCapabilities` in db/queries). A nav link tagged with one is hidden when the
+ * data behind it is absent — e.g. TURD on a non-Py mod set. See #68. */
+export type NavCapabilities = { hasTurd: boolean };
+
+export type NavLink = {
+  to: NavLinkTo;
+  label: string;
+  icon: LucideIcon;
+  /** Hidden once we know the dataset lacks this capability; absent → always shown. */
+  capability?: keyof NavCapabilities;
+};
 
 /** The primary cluster (left side of the desktop bar). */
 export const NAV_LINKS: NavLink[] = [
@@ -31,10 +42,17 @@ export const NAV_LINKS: NavLink[] = [
   { to: "/factory", label: "Factory", icon: Factory },
   { to: "/coherence", label: "Coherence", icon: ArrowLeftRight },
   { to: "/browse", label: "Browse", icon: Search },
-  { to: "/turd", label: "TURD", icon: FlaskConical },
+  { to: "/turd", label: "TURD", icon: FlaskConical, capability: "hasTurd" },
   { to: "/assistant", label: "Assistant", icon: Sparkles },
   { to: "/tasks", label: "Tasks", icon: ListChecks },
 ];
 
+/** Nav links to show for the given capabilities. A capability-tagged link is hidden
+ * only once caps are loaded and the flag is explicitly false — so it never flashes
+ * out while caps are still loading (the common Py case shows it immediately). */
+export function visibleNavLinks(caps: NavCapabilities | undefined): NavLink[] {
+  return NAV_LINKS.filter((l) => !l.capability || caps?.[l.capability] !== false);
+}
+
 /** Settings sits in the right cluster on desktop; folded in with the rest on mobile. */
 export const SETTINGS_LINK: NavLink = { to: "/settings", label: "Settings", icon: Settings };
diff --git a/app/src/components/nav-mobile.tsx b/app/src/components/nav-mobile.tsx
index bc951925..3d99fbee 100644
--- a/app/src/components/nav-mobile.tsx
+++ b/app/src/components/nav-mobile.tsx
@@ -1,12 +1,14 @@
 import { useState } from "react";
 import { Link } from "@tanstack/react-router";
+import { useQuery } from "@tanstack/react-query";
 import { Menu } from "lucide-react";
 import { Sheet, SheetContent, SheetHeader, SheetTitle, SheetTrigger } from "./ui/sheet";
-import { NAV_LINKS, SETTINGS_LINK } from "./nav-links";
+import { SETTINGS_LINK, visibleNavLinks } from "./nav-links";
 import { HorizonMenu } from "./horizon-menu";
 import { LogisticsMenu } from "./logistics-menu";
 import { BridgeIndicator } from "./bridge-indicator";
 import { ProjectSwitcher } from "./project-switcher";
+import { dataCapabilitiesFn } from "../server/factorio";
 
 // Touch-sized rows (h-12 = 48px) — comfortably tappable, unlike the dense h-10
 // desktop bar that's tuned for a mouse pointer.
@@ -19,7 +21,8 @@ const rowActive = "!text-foreground bg-muted/40 border-l-2 border-primary";
  * Rendered alongside the desktop bar in app-nav; each is gated at the same width. */
 export function NavMobile() {
   const [open, setOpen] = useState(false);
-  const links = [...NAV_LINKS, SETTINGS_LINK];
+  const caps = useQuery({ queryKey: ["dataCapabilities"], queryFn: () => dataCapabilitiesFn() });
+  const links = [...visibleNavLinks(caps.data), SETTINGS_LINK];
 
   return (
     <div className="flex flex-1 items-stretch justify-end min-[1400px]:hidden">
diff --git a/app/src/db/queries.test.ts b/app/src/db/queries.test.ts
index da8b7006..b09f9c13 100644
--- a/app/src/db/queries.test.ts
+++ b/app/src/db/queries.test.ts
@@ -6,6 +6,7 @@ import {
   blockReferenceFingerprint,
   buildCost,
   createGroup,
+  dataCapabilities,
   deleteGroup,
   getResearchHorizon,
   goodExists,
@@ -70,6 +71,19 @@ describe("goodGraphCounts", () => {
   });
 });
 
+describe("dataCapabilities", () => {
+  it("reports hasTurd false when the dataset has no TURD techs", () => {
+    expect(dataCapabilities()).toEqual({ hasTurd: false });
+  });
+
+  it("reports hasTurd true once a TURD master tech is present", () => {
+    db.run(
+      sql`INSERT INTO technologies (name, unit_count, enabled, is_turd) VALUES ('t-master', 1, 1, 1)`,
+    );
+    expect(dataCapabilities()).toEqual({ hasTurd: true });
+  });
+});
+
 describe("setBuiltMachines + machineSufficiency", () => {
   it("records built counts and computes the per-recipe shortfall", () => {
     const res = setBuiltMachines([{ machine: "furnace", recipe: "smelt-plate", count: 7 }]);
diff --git a/app/src/db/queries.ts b/app/src/db/queries.ts
index df93f1b2..255f54a8 100644
--- a/app/src/db/queries.ts
+++ b/app/src/db/queries.ts
@@ -2561,6 +2561,22 @@ export function costAnalysisCount(): number {
 }
 
 /** Row counts — useful for a health check / "is the db loaded" probe. */
+/** Which data-driven, mod-specific surfaces the loaded dataset actually supports,
+ * so the UI can hide features that have no data behind them (e.g. TURD when the
+ * Pyanodons alien-life mods aren't part of the synced mod set). Keyed on the data
+ * being present, not on sniffing for a named mod — see #68 for the broader
+ * mod-agnostic goal. */
+export function dataCapabilities(): { hasTurd: boolean } {
+  const turd = (
+    db
+      .select({ n: sql<number>`count(*)` })
+      .from(technologies)
+      .where(eq(technologies.isTurd, true))
+      .get() as { n: number }
+  ).n;
+  return { hasTurd: turd > 0 };
+}
+
 export function stats() {
   const count = (t: Parameters<ReturnType<typeof db.select>["from"]>[0]) =>
     (
diff --git a/app/src/routes/turd.tsx b/app/src/routes/turd.tsx
index 4923c7f4..793dc11b 100644
--- a/app/src/routes/turd.tsx
+++ b/app/src/routes/turd.tsx
@@ -142,6 +142,14 @@ function TurdPage() {
 
       {upgrades.isLoading && <div className="text-muted-foreground">loading…</div>}
 
+      {!upgrades.isLoading && (upgrades.data?.length ?? 0) === 0 && (
+        <div className="max-w-prose text-sm text-muted-foreground">
+          No TURD upgrades in this dataset. TURD is a Pyanodons mechanic — sync a mod set that
+          includes it (e.g. pyalienlife) and its upgrades appear here. (This tab is hidden from the
+          nav when there&apos;s no TURD data.)
+        </div>
+      )}
+
       <div className="grid grid-cols-1 gap-3 lg:grid-cols-2 2xl:grid-cols-3">
         {list.map((u) => (
           <Card key={u.name} className="p-3">
diff --git a/app/src/server/factorio.ts b/app/src/server/factorio.ts
index 21804697..4a18aa41 100644
--- a/app/src/server/factorio.ts
+++ b/app/src/server/factorio.ts
@@ -31,6 +31,9 @@ function pseudoDisplay(name: string) {
 }
 
 export const statsFn = createServerFn({ method: "GET" }).handler(async () => (await lib()).stats());
+export const dataCapabilitiesFn = createServerFn({ method: "GET" }).handler(async () =>
+  (await lib()).dataCapabilities(),
+);
 
 export const searchItemsFn = createServerFn({ method: "GET" })
   .validator((query: string) => query)