Only allow Tauri imports in the desktop app (#5995)

# Description of Changes Adds an eslint rule to disallow importing any Tauri APIs outside the desktop folder to help hint to developers that they should be following the frontend architecture. While doing this, I also discovered that you can provide a custom message in the `no-restricted-imports` rule, which is nicer than the comments that I'd previously added to the eslint config file to explain why they weren't allowed: ```text /Users/jamesbrunton/Dev/spdf1/frontend/src/core/components/shared/config/configSections/GeneralSection.tsx 19:1 error 'src/core/contexts/PreferencesContext' import is restricted from being used by a pattern. Use @app/* imports instead of absolute src/ imports no-restricted-imports 20:1 error '../../../../../core/contexts/AppConfigContext' import is restricted from being used by a pattern. Use @app/* imports instead of relative imports no-restricted-imports 21:1 error '@tauri-apps/core' import is restricted from being used by a pattern. Tauri APIs are desktop-only. Review frontend/DeveloperGuide.md for structure advice no-restricted-imports ```
2026-04-06 03:19:39 +02:00 · 2026-03-30 15:24:16 +01:00
parent 0e29640766
commit 4a6b426651
5 changed files with 161 additions and 58 deletions
--- a/frontend/DeveloperGuide.md
+++ b/frontend/DeveloperGuide.md
@@ -45,6 +45,84 @@ export function f2() { /* ... */ } // Custom desktop implementation

 Building with this pattern minimises the duplicated code in the system and greatly reduces the chances that changing the core app will break the desktop app.

+### Naming extension modules
+
+Extension modules and the functions/hooks they export should be named after **what they do**, not **which build overrides them**.
+Core code must never reference build targets (desktop, saas, etc.) by name — it should simply call a generic extension point and remain unaware of which layer is providing the implementation.
+
+```ts
+// ✅ CORRECT - named after the behaviour, not the build
+// core/useFrontendVersionInfo.ts
+export function useFrontendVersionInfo() { /* stub */ }
+
+// desktop/useFrontendVersionInfo.ts
+export function useFrontendVersionInfo() { /* real Tauri implementation */ }
+```
+
+```ts
+// ❌ WRONG - core code reveals knowledge of the desktop layer
+// core/useDesktopVersionInfo.ts
+export function useDesktopVersionInfo() { /* stub */ }
+```
+
+Similarly, core code should never contain conditionals that check which build is active (e.g. `if (isDesktop)`).
+If behaviour needs to vary, that variation belongs in an extension module - the core simply calls it.
+
+The same principle applies in reverse: code inside `desktop/` is guaranteed to be running in the Tauri environment, so `isTauri()` checks are never needed there either.
+If you find yourself writing `if (isDesktop())` or `if (isTauri())` anywhere, that is a sign the extension point has not been modelled correctly - the build system is already doing that separation for you.
+
+### List extensions
+
+When a build needs to _add_ behaviour rather than _replace_ it, the extension module can return a list of items and let core manage the rendering.
+Core defines the function to return an empty list; the extension build overrides it to return a populated one.
+
+```ts
+// core/toolbarExtensions.ts
+export interface ToolbarButton {
+  label: string;
+  onClick: () => void;
+}
+
+export function getToolbarButtons(): ToolbarButton[] {
+  return [];
+}
+```
+
+```ts
+// desktop/toolbarExtensions.ts
+import { type ToolbarButton } from '@core/toolbarExtensions';
+export { type ToolbarButton };
+
+export function getToolbarButtons(): ToolbarButton[] {
+  return [
+    { label: 'Open folder', onClick: () => { /* ... */ } },
+  ];
+}
+```
+
+```tsx
+// core/Toolbar.tsx
+import { getToolbarButtons } from '@app/toolbarExtensions';
+
+export function Toolbar() {
+  return (
+    <div>
+      <button onClick={() => { /* ... */ }}>Download</button>
+      <button onClick={() => { /* ... */ }}>Print</button>
+      {getToolbarButtons().map((button) => (
+        <button key={button.label} onClick={button.onClick}>
+          {button.label}
+        </button>
+      ))}
+    </div>
+  );
+}
+```
+
+This pattern works well for things like menu items or toolbar actions - anything where a build contributes additional entries to a well-defined set.
+
+### Import aliases
+
 In general, all imports for app code should come via `@app` because it allows for other builds of the app to override behaviour if necessary.
 The only time that it is beneficial to import via a specific folder (e.g. `@core`) is when you want to reduce duplication **in the file you are overriding**. For example:

--- a/frontend/eslint.config.mjs
+++ b/frontend/eslint.config.mjs
@@ -13,6 +13,11 @@ const nodeGlobs = [
  '*.config.{js,ts,mjs}',
 ];

+const baseRestrictedImportPatterns = [
+  { regex: '^\\.', message: "Use @app/* imports instead of relative imports." },
+  { regex: '^src/', message: "Use @app/* imports instead of absolute src/ imports." },
+];
+
 export default defineConfig(
  {
    // Everything that contains 3rd party code that we don't want to lint
@@ -30,10 +35,7 @@ export default defineConfig(
      'no-restricted-imports': [
        'error',
        {
-          patterns: [
-            ".*", // Disallow any relative imports (they should be '@app/x/y/z' or similar)
-            "src/*", // Disallow any absolute imports (they should be '@app/x/y/z' or similar)
-          ],
+          patterns: baseRestrictedImportPatterns,
        },
      ],
      '@typescript-eslint/no-empty-object-type': [
@@ -59,6 +61,26 @@ export default defineConfig(
      ],
    },
  },
+  // Desktop-only packages must not be imported from core or proprietary code.
+  // Use the stub/shadow pattern instead: define a stub in src/core/ and override in src/desktop/.
+  {
+    files: srcGlobs,
+    ignores: ['src/desktop/**'],
+    rules: {
+      'no-restricted-imports': [
+        'error',
+        {
+          patterns: [
+            ...baseRestrictedImportPatterns,
+            {
+              regex: '^@tauri-apps/',
+              message: "Tauri APIs are desktop-only. Review frontend/DeveloperGuide.md for structure advice.",
+            },
+          ],
+        },
+      ],
+    },
+  },
  // Folders that have been cleaned up and are now conformant - stricter rules enforced here
  {
    files: ['src/saas/**/*.{js,mjs,jsx,ts,tsx}'],
--- a/frontend/src/core/components/shared/config/configSections/GeneralSection.tsx
+++ b/frontend/src/core/components/shared/config/configSections/GeneralSection.tsx
@@ -1,4 +1,4 @@
-import React, { useState, useEffect, useMemo } from "react";
+import React, { useState, useEffect } from "react";
 import {
  Paper,
  Stack,
@@ -22,8 +22,7 @@ import type { ToolPanelMode } from "@app/constants/toolPanel";
 import LocalIcon from "@app/components/shared/LocalIcon";
 import { updateService, UpdateSummary } from "@app/services/updateService";
 import UpdateModal from "@app/components/shared/UpdateModal";
-import { getVersion } from "@tauri-apps/api/app";
-import { isTauri } from "@tauri-apps/api/core";
+import { useFrontendVersionInfo } from "@app/hooks/useFrontendVersionInfo";

 const DEFAULT_AUTO_UNZIP_FILE_LIMIT = 4;
 const BANNER_DISMISSED_KEY = "stirlingpdf_features_banner_dismissed";
@@ -46,10 +45,8 @@ const GeneralSection: React.FC<GeneralSectionProps> = ({ hideTitle = false, hide
  const [updateSummary, setUpdateSummary] = useState<UpdateSummary | null>(null);
  const [updateModalOpened, setUpdateModalOpened] = useState(false);
  const [checkingUpdate, setCheckingUpdate] = useState(false);
-  const [mismatchVersion, setMismatchVersion] = useState(false);
-  const isTauriApp = useMemo(() => isTauri(), []);
-  const [appVersion, setAppVersion] = useState<string | null>(null);
-  const frontendVersionLabel = appVersion ?? t("common.loading", "Loading...");
+  const { appVersion, mismatchVersion } = useFrontendVersionInfo(config?.appVersion);
+  const frontendVersionLabel = appVersion ?? t("common.loading", "Loading..."); // null = loading, shown only when appVersion !== undefined

  // Sync local state with preference changes
  useEffect(() => {
@@ -91,52 +88,6 @@ const GeneralSection: React.FC<GeneralSectionProps> = ({ hideTitle = false, hide
    setCheckingUpdate(false);
  };

-  useEffect(() => {
-    if (!isTauriApp) {
-      setMismatchVersion(false);
-      return;
-    }
-
-    let cancelled = false;
-    const fetchFrontendVersion = async () => {
-      try {
-        const frontendVersion = await getVersion();
-        if (!cancelled) {
-          setAppVersion(frontendVersion);
-        }
-      } catch (error) {
-        console.error("[GeneralSection] Failed to fetch frontend version:", error);
-      }
-    };
-
-    fetchFrontendVersion();
-
-    return () => {
-      cancelled = true;
-    };
-  }, [isTauriApp]);
-
-  useEffect(() => {
-    if (!isTauriApp) {
-      return;
-    }
-
-    if (!appVersion || !config?.appVersion) {
-      setMismatchVersion(false);
-      return;
-    }
-
-    if (appVersion !== config.appVersion) {
-      console.warn("[GeneralSection] Mismatch between Tauri version and AppConfig version:", {
-        backendVersion: config.appVersion,
-        frontendVersion: appVersion,
-      });
-      setMismatchVersion(true);
-    } else {
-      setMismatchVersion(false);
-    }
-  }, [isTauriApp, appVersion, config?.appVersion]);
-
  // Check if login is disabled
  const loginDisabled = !config?.enableLogin;

@@ -239,7 +190,7 @@ const GeneralSection: React.FC<GeneralSectionProps> = ({ hideTitle = false, hide
                )}
              </Group>
            </div>
-            {isTauriApp && (
+            {appVersion !== undefined && (
              <Group justify="space-between" align="center">
                <div>
                  <Text size="sm" c="dimmed">
--- a/frontend/src/core/hooks/useFrontendVersionInfo.ts
+++ b/frontend/src/core/hooks/useFrontendVersionInfo.ts
@@ -0,0 +1,8 @@
+export interface FrontendVersionInfo {
+  appVersion: string | null | undefined; // undefined = not applicable, null = loading, string = loaded
+  mismatchVersion: boolean;
+}
+
+export function useFrontendVersionInfo(_backendVersion: string | undefined): FrontendVersionInfo {
+  return { appVersion: undefined, mismatchVersion: false };
+}
--- a/frontend/src/desktop/hooks/useFrontendVersionInfo.ts
+++ b/frontend/src/desktop/hooks/useFrontendVersionInfo.ts
@@ -0,0 +1,44 @@
+import { useState, useEffect } from "react";
+import { getVersion } from "@tauri-apps/api/app";
+import type { FrontendVersionInfo } from "@core/hooks/useFrontendVersionInfo";
+
+export function useFrontendVersionInfo(backendVersion: string | undefined): FrontendVersionInfo {
+  const [appVersion, setAppVersion] = useState<string | null>(null);
+  const [mismatchVersion, setMismatchVersion] = useState(false);
+
+  useEffect(() => {
+    let cancelled = false;
+    const fetchVersion = async () => {
+      try {
+        const version = await getVersion();
+        if (!cancelled) {
+          setAppVersion(version);
+        }
+      } catch (error) {
+        console.error("[useFrontendVersionInfo] Failed to fetch frontend version:", error);
+      }
+    };
+    fetchVersion();
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+
+  useEffect(() => {
+    if (!appVersion || !backendVersion) {
+      setMismatchVersion(false);
+      return;
+    }
+    if (appVersion !== backendVersion) {
+      console.warn("[useFrontendVersionInfo] Mismatch between frontend version and AppConfig version:", {
+        backendVersion,
+        frontendVersion: appVersion,
+      });
+      setMismatchVersion(true);
+    } else {
+      setMismatchVersion(false);
+    }
+  }, [appVersion, backendVersion]);
+
+  return { appVersion, mismatchVersion };
+}