Show a reset confirmation in the Framey sample

examples/framey-settings/README.md

@@ -14,9 +14,20 @@ action calls the backend, so it reads the persisted setting rather than a
 browser cache. A missing, damaged, or old non-boolean value reads as the
 caller's default;
 the next save atomically replaces the sample's settings file.
+The current file is `{"schema": 1, "enabled": true|false}`. An unversioned
+`{"enabled": true|false}` file from the first sample release still reads, and
+the next save writes schema 1. A file with another explicit schema returns a
+visible read or save error and remains untouched, so downgrading the sample
+cannot erase settings written by a newer version. Add a deliberate migration
+for each future schema instead of changing this guard silently.
 The panel also guards its own read and write calls synchronously. If two
 controller events arrive before React redraws a disabled control, the second
 event is ignored; after the request settles, a new change can be saved.
+**Reset example setting** opens a local `ConfirmModal`. **Keep setting** closes
+it without a backend call; **Reset** saves `false` through the same guarded
+write path as the toggle. This is a safe example of putting a settings change
+behind an explicit confirmation in Framey. It has not been tried with a
+physical controller in a worn headset.
 
 The **About this setting** button opens a local detail page at
 `/framey-sample/details/saved-setting`. It demonstrates `routerHook.addRoute`,
@@ -48,7 +59,8 @@ plugin directory does not enable its VR panel.
 Run `python3 -m unittest discover -s tests -p test_framey_sample.py` from the
 repository root. It checks backend persistence and evaluates the built bundle
 against Framey's actual host script, including the quick action's scoped
-backend call and local route registration/navigation. The fake Frame store flow is exercised by
+backend call, modal cancel/confirm behavior, and local route
+registration/navigation. The fake Frame store flow is exercised by
 the repository's e2e suite. No worn-headset visibility or controller-input test
 has passed for this sample yet.
 

examples/framey-settings/dist/index.js

@@ -31,6 +31,7 @@ function Content() {
     const [busy, setBusy] = SP_REACT.useState(true);
     const [message, setMessage] = SP_REACT.useState('Loading setting…');
     const pending = SP_REACT.useRef(false);
+    const resetModalOpen = SP_REACT.useRef(false);
     async function refresh() {
         if (pending.current)
             return;
@@ -72,7 +73,14 @@ function Content() {
             setBusy(false);
         }
     }
-    return SP_JSX.jsxs(DFL.PanelSection, { title: "Framey settings sample", children: [SP_JSX.jsx(DFL.PanelSectionRow, { children: SP_JSX.jsx(DFL.ToggleField, { label: "Example setting", description: "Stored by the Decky Python backend", checked: enabled, disabled: busy, onChange: (value) => { void change(value); } }) }), SP_JSX.jsx(DFL.PanelSectionRow, { children: SP_JSX.jsx(DFL.ButtonItem, { disabled: busy, onClick: () => { void refresh(); }, children: "Reload saved setting" }) }), SP_JSX.jsx(DFL.PanelSectionRow, { children: SP_JSX.jsx(DFL.ButtonItem, { onClick: () => DFL.Navigation.Navigate('/framey-sample/details/saved-setting'), children: "About this setting" }) }), SP_JSX.jsx(DFL.PanelSectionRow, { children: SP_JSX.jsx("p", { role: "status", children: message }) })] });
+    function confirmReset() {
+        if (pending.current || resetModalOpen.current)
+            return;
+        const dialog = DFL.showModal(SP_JSX.jsx(DFL.ConfirmModal, { strTitle: "Reset example setting?", strDescription: "This changes only the sample plugin's saved setting.", strOKButtonText: "Reset", strCancelButtonText: "Keep setting", onOK: () => { void change(false); } }));
+        resetModalOpen.current = true;
+        void dialog.ClosedPromise.then(() => { resetModalOpen.current = false; });
+    }
+    return SP_JSX.jsxs(DFL.PanelSection, { title: "Framey settings sample", children: [SP_JSX.jsx(DFL.PanelSectionRow, { children: SP_JSX.jsx(DFL.ToggleField, { label: "Example setting", description: "Stored by the Decky Python backend", checked: enabled, disabled: busy, onChange: (value) => { void change(value); } }) }), SP_JSX.jsx(DFL.PanelSectionRow, { children: SP_JSX.jsx(DFL.ButtonItem, { disabled: busy, onClick: () => { void refresh(); }, children: "Reload saved setting" }) }), SP_JSX.jsx(DFL.PanelSectionRow, { children: SP_JSX.jsx(DFL.ButtonItem, { disabled: busy, onClick: confirmReset, children: "Reset example setting" }) }), SP_JSX.jsx(DFL.PanelSectionRow, { children: SP_JSX.jsx(DFL.ButtonItem, { onClick: () => DFL.Navigation.Navigate('/framey-sample/details/saved-setting'), children: "About this setting" }) }), SP_JSX.jsx(DFL.PanelSectionRow, { children: SP_JSX.jsx("p", { role: "status", children: message }) })] });
 }
 function Details() {
     const { topic } = DFL.useParams();

examples/framey-settings/dist/index.js.map

@@ -1 +1 @@
-{"version":3,"file":"index.js","sources":["decky://decky/plugin/Framey%20Settings%20Sample/node_modules/.pnpm/@decky+api@1.1.3/node_modules/@decky/api/dist/index.js","decky://decky/plugin/Framey%20Settings%20Sample/src/index.tsx"],"sourcesContent":["import _manifest from '@decky/manifest';\nexport * from \"./types\";\nconst manifest = _manifest;\nconst API_VERSION = 2;\nif (!manifest?.name) {\n    throw new Error('[@decky/api]: Failed to find plugin manifest.');\n}\nconst internalAPIConnection = window.__DECKY_SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED_deckyLoaderAPIInit;\nif (!internalAPIConnection) {\n    throw new Error('[@decky/api]: Failed to connect to the loader as as the loader API was not initialized. This is likely a bug in Decky Loader.');\n}\nlet api;\ntry {\n    api = internalAPIConnection.connect(API_VERSION, manifest.name);\n}\ncatch {\n    api = internalAPIConnection.connect(1, manifest.name);\n    console.warn(`[@decky/api] Requested API version ${API_VERSION} but the running loader only supports version 1. Some features may not work.`);\n}\nif (api._version != API_VERSION) {\n    console.warn(`[@decky/api] Requested API version ${API_VERSION} but the running loader only supports version ${api._version}. Some features may not work.`);\n}\nexport const call = api.call;\nexport const callable = api.callable;\nexport const addEventListener = api.addEventListener;\nexport const removeEventListener = api.removeEventListener;\nexport const routerHook = api.routerHook;\nexport const toaster = api.toaster;\nexport const openFilePicker = api.openFilePicker;\nexport const executeInTab = api.executeInTab;\nexport const injectCssIntoTab = api.injectCssIntoTab;\nexport const removeCssFromTab = api.removeCssFromTab;\nexport const fetchNoCors = api.fetchNoCors;\nexport const getExternalResourceURL = api.getExternalResourceURL;\nexport const useQuickAccessVisible = api.useQuickAccessVisible;\nexport const definePlugin = (fn) => {\n    return (...args) => {\n        return fn(...args);\n    };\n};\n","import {callable, definePlugin, routerHook, toaster} from '@decky/api';\nimport {ButtonItem, Navigation, PanelSection, PanelSectionRow, ToggleField, useParams} from '@decky/ui';\nimport {useEffect, useRef, useState} from 'react';\n\nconst getSetting = callable<[key: string, fallback: boolean], boolean>('get_setting');\nconst setSetting = callable<[key: string, value: boolean], boolean>('set_setting');\n\nfunction Content() {\n  const [enabled, setEnabled] = useState(false);\n  const [busy, setBusy] = useState(true);\n  const [message, setMessage] = useState('Loading setting…');\n  const pending = useRef(false);\n\n  async function refresh() {\n    if (pending.current) return;\n    pending.current = true;\n    setBusy(true);\n    try {\n      const value = await getSetting('enabled', false);\n      setEnabled(value);\n      setMessage(`Saved setting: ${value ? 'on' : 'off'}`);\n    } catch (error) {\n      setMessage(`Could not read setting: ${String(error)}`);\n    } finally {\n      pending.current = false;\n      setBusy(false);\n    }\n  }\n\n  useEffect(() => {void refresh();}, []);\n\n  async function change(value: boolean) {\n    // Two controller events can arrive before React redraws the disabled toggle.\n    // Keep writes ordered so a late first reply cannot replace the final choice.\n    if (pending.current) return;\n    pending.current = true;\n    setBusy(true);\n    try {\n      await setSetting('enabled', value);\n      setEnabled(value);\n      setMessage(`Saved setting: ${value ? 'on' : 'off'}`);\n      toaster.toast({title: 'Framey sample',\n        body: <span>Setting saved: <strong>{value ? 'on' : 'off'}</strong></span>});\n    } catch (error) {\n      setMessage(`Could not save setting: ${String(error)}`);\n    } finally {\n      pending.current = false;\n      setBusy(false);\n    }\n  }\n\n  return <PanelSection title=\"Framey settings sample\">\n    <PanelSectionRow>\n      <ToggleField label=\"Example setting\" description=\"Stored by the Decky Python backend\"\n        checked={enabled} disabled={busy} onChange={(value: boolean) => {void change(value);}} />\n    </PanelSectionRow>\n    <PanelSectionRow><ButtonItem disabled={busy} onClick={() => {void refresh();}}>Reload saved setting</ButtonItem></PanelSectionRow>\n    <PanelSectionRow><ButtonItem onClick={() => Navigation.Navigate('/framey-sample/details/saved-setting')}>About this setting</ButtonItem></PanelSectionRow>\n    <PanelSectionRow><p role=\"status\">{message}</p></PanelSectionRow>\n  </PanelSection>;\n}\n\nfunction Details() {\n  const {topic} = useParams<{topic?: string}>();\n  return <PanelSection title=\"Sample detail page\">\n    <PanelSectionRow><p>Topic: {topic || 'overview'}</p></PanelSectionRow>\n    <PanelSectionRow><p>The toggle is stored by this plugin's Decky backend in the user's settings directory.</p></PanelSectionRow>\n    <PanelSectionRow><ButtonItem onClick={() => Navigation.NavigateBack()}>Back Line truncated
+{"version":3,"file":"index.js","sources":["decky://decky/plugin/Framey%20Settings%20Sample/node_modules/.pnpm/@decky+api@1.1.3/node_modules/@decky/api/dist/index.js","decky://decky/plugin/Framey%20Settings%20Sample/src/index.tsx"],"sourcesContent":["import _manifest from '@decky/manifest';\nexport * from \"./types\";\nconst manifest = _manifest;\nconst API_VERSION = 2;\nif (!manifest?.name) {\n    throw new Error('[@decky/api]: Failed to find plugin manifest.');\n}\nconst internalAPIConnection = window.__DECKY_SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED_deckyLoaderAPIInit;\nif (!internalAPIConnection) {\n    throw new Error('[@decky/api]: Failed to connect to the loader as as the loader API was not initialized. This is likely a bug in Decky Loader.');\n}\nlet api;\ntry {\n    api = internalAPIConnection.connect(API_VERSION, manifest.name);\n}\ncatch {\n    api = internalAPIConnection.connect(1, manifest.name);\n    console.warn(`[@decky/api] Requested API version ${API_VERSION} but the running loader only supports version 1. Some features may not work.`);\n}\nif (api._version != API_VERSION) {\n    console.warn(`[@decky/api] Requested API version ${API_VERSION} but the running loader only supports version ${api._version}. Some features may not work.`);\n}\nexport const call = api.call;\nexport const callable = api.callable;\nexport const addEventListener = api.addEventListener;\nexport const removeEventListener = api.removeEventListener;\nexport const routerHook = api.routerHook;\nexport const toaster = api.toaster;\nexport const openFilePicker = api.openFilePicker;\nexport const executeInTab = api.executeInTab;\nexport const injectCssIntoTab = api.injectCssIntoTab;\nexport const removeCssFromTab = api.removeCssFromTab;\nexport const fetchNoCors = api.fetchNoCors;\nexport const getExternalResourceURL = api.getExternalResourceURL;\nexport const useQuickAccessVisible = api.useQuickAccessVisible;\nexport const definePlugin = (fn) => {\n    return (...args) => {\n        return fn(...args);\n    };\n};\n","import {callable, definePlugin, routerHook, toaster} from '@decky/api';\nimport {ButtonItem, ConfirmModal, Navigation, PanelSection, PanelSectionRow, ToggleField, showModal, useParams} from '@decky/ui';\nimport {useEffect, useRef, useState} from 'react';\n\nconst getSetting = callable<[key: string, fallback: boolean], boolean>('get_setting');\nconst setSetting = callable<[key: string, value: boolean], boolean>('set_setting');\n\nfunction Content() {\n  const [enabled, setEnabled] = useState(false);\n  const [busy, setBusy] = useState(true);\n  const [message, setMessage] = useState('Loading setting…');\n  const pending = useRef(false);\n  const resetModalOpen = useRef(false);\n\n  async function refresh() {\n    if (pending.current) return;\n    pending.current = true;\n    setBusy(true);\n    try {\n      const value = await getSetting('enabled', false);\n      setEnabled(value);\n      setMessage(`Saved setting: ${value ? 'on' : 'off'}`);\n    } catch (error) {\n      setMessage(`Could not read setting: ${String(error)}`);\n    } finally {\n      pending.current = false;\n      setBusy(false);\n    }\n  }\n\n  useEffect(() => {void refresh();}, []);\n\n  async function change(value: boolean) {\n    // Two controller events can arrive before React redraws the disabled toggle.\n    // Keep writes ordered so a late first reply cannot replace the final choice.\n    if (pending.current) return;\n    pending.current = true;\n    setBusy(true);\n    try {\n      await setSetting('enabled', value);\n      setEnabled(value);\n      setMessage(`Saved setting: ${value ? 'on' : 'off'}`);\n      toaster.toast({title: 'Framey sample',\n        body: <span>Setting saved: <strong>{value ? 'on' : 'off'}</strong></span>});\n    } catch (error) {\n      setMessage(`Could not save setting: ${String(error)}`);\n    } finally {\n      pending.current = false;\n      setBusy(false);\n    }\n  }\n\n  function confirmReset() {\n    if (pending.current || resetModalOpen.current) return;\n    const dialog = showModal(<ConfirmModal strTitle=\"Reset example setting?\"\n      strDescription=\"This changes only the sample plugin's saved setting.\"\n      strOKButtonText=\"Reset\" strCancelButtonText=\"Keep setting\"\n      onOK={() => {void change(false);}} />);\n    resetModalOpen.current = true;\n    void dialog.ClosedPromise.then(() => {resetModalOpen.current = false;});\n  }\n\n  return <PanelSection title=\"Framey settings sample\">\n    <PanelSectionRow>\n      <ToggleField label=\"Example setting\" description=\"Stored by the Decky Python backend\"\n        checked={enabled} disabled={busy} onChange={(value: boolean) => {void change(value);}} />\n    </PanelSectionRow>\n    <PanelSectionRow><ButtonItem disabled={busy} onClick={() => {void refresh();}}>Reload saved setting</ButtonItem></PanelSectionRow>\n    <PanelSectionRow><ButtonItem disabled={busy} onClick={confirmReset}>Reset example setting</ButtonItem></PanelSectionRLine truncated

examples/framey-settings/main.py

@@ -5,26 +5,41 @@ from pathlib import Path
 import tempfile
 import decky
 
+SETTINGS_SCHEMA = 1
+
 
 def settings_file():
     # Decky provides this per-plugin path through its official Python module.
     return Path(decky.DECKY_PLUGIN_SETTINGS_DIR) / 'settings.json'
 
 
+def read_settings():
+    try:
+        stored = json.loads(settings_file().read_text(encoding='utf-8'))
+    except (FileNotFoundError, json.JSONDecodeError, UnicodeDecodeError):
+        return {}
+    if not isinstance(stored, dict):
+        return {}
+    # The first sample release wrote {"enabled": bool} without a schema.
+    # Keep reading it; the next save writes the current format.
+    schema = stored.get('schema', SETTINGS_SCHEMA)
+    if type(schema) is not int or schema != SETTINGS_SCHEMA:
+        raise ValueError('Settings were written by an unsupported sample version')
+    return stored
+
+
 class Plugin:
     async def get_setting(self, key: str, default=False):
         if key != 'enabled':
             raise ValueError('Unknown setting')
-        try:
-            stored = json.loads(settings_file().read_text(encoding='utf-8'))
-        except (FileNotFoundError, json.JSONDecodeError, UnicodeDecodeError):
-            return default
-        value = stored.get(key) if isinstance(stored, dict) else None
+        value = read_settings().get(key)
         return value if type(value) is bool else default
 
     async def set_setting(self, key: str, value: bool):
         if key != 'enabled' or type(value) is not bool:
             raise ValueError('Expected an enabled boolean')
+        # Refuse to erase settings from a newer plugin after a downgrade.
+        read_settings()
         target = settings_file()
         target.parent.mkdir(mode=0o700, parents=True, exist_ok=True)
         temporary = None
@@ -32,7 +47,7 @@ class Plugin:
             with tempfile.NamedTemporaryFile('w', encoding='utf-8', dir=target.parent,
                                              prefix='.settings-', delete=False) as output:
                 temporary = Path(output.name)
-                json.dump({'enabled': value}, output)
+                json.dump({'schema': SETTINGS_SCHEMA, 'enabled': value}, output)
                 output.write('\n')
             temporary.chmod(0o600)
             os.replace(temporary, target)

examples/framey-settings/src/index.tsx

@@ -1,5 +1,5 @@
 import {callable, definePlugin, routerHook, toaster} from '@decky/api';
-import {ButtonItem, Navigation, PanelSection, PanelSectionRow, ToggleField, useParams} from '@decky/ui';
+import {ButtonItem, ConfirmModal, Navigation, PanelSection, PanelSectionRow, ToggleField, showModal, useParams} from '@decky/ui';
 import {useEffect, useRef, useState} from 'react';
 
 const getSetting = callable<[key: string, fallback: boolean], boolean>('get_setting');
@@ -10,6 +10,7 @@ function Content() {
   const [busy, setBusy] = useState(true);
   const [message, setMessage] = useState('Loading setting…');
   const pending = useRef(false);
+  const resetModalOpen = useRef(false);
 
   async function refresh() {
     if (pending.current) return;
@@ -49,12 +50,23 @@ function Content() {
     }
   }
 
+  function confirmReset() {
+    if (pending.current || resetModalOpen.current) return;
+    const dialog = showModal(<ConfirmModal strTitle="Reset example setting?"
+      strDescription="This changes only the sample plugin's saved setting."
+      strOKButtonText="Reset" strCancelButtonText="Keep setting"
+      onOK={() => {void change(false);}} />);
+    resetModalOpen.current = true;
+    void dialog.ClosedPromise.then(() => {resetModalOpen.current = false;});
+  }
+
   return <PanelSection title="Framey settings sample">
     <PanelSectionRow>
       <ToggleField label="Example setting" description="Stored by the Decky Python backend"
         checked={enabled} disabled={busy} onChange={(value: boolean) => {void change(value);}} />
     </PanelSectionRow>
     <PanelSectionRow><ButtonItem disabled={busy} onClick={() => {void refresh();}}>Reload saved setting</ButtonItem></PanelSectionRow>
+    <PanelSectionRow><ButtonItem disabled={busy} onClick={confirmReset}>Reset example setting</ButtonItem></PanelSectionRow>
     <PanelSectionRow><ButtonItem onClick={() => Navigation.Navigate('/framey-sample/details/saved-setting')}>About this setting</ButtonItem></PanelSectionRow>
     <PanelSectionRow><p role="status">{message}</p></PanelSectionRow>
   </PanelSection>;

tests/page/framey_sample.mjs

@@ -8,6 +8,7 @@ const bundle=readFileSync(new URL('../../examples/framey-settings/dist/index.js'
 assert.match(bundle,/SP_JSX\.jsx/);
 const React={Fragment:Symbol('fragment'),Component:class {},
   createElement:(type,props,...children)=>({type,props:props||{},children}),
+  cloneElement:(element,props)=>({...element,props:{...element.props,...props}}),
   useState:value=>[value,()=>{}],useRef:value=>({current:value}),
   useEffect(){},isValidElement:value=>!!value?.type};
 class Element {
@@ -71,6 +72,28 @@ toggle.props.onChange(false);
 await new Promise(resolve=>setImmediate(resolve));
 assert.equal(calls.filter(call=>call.method==='set_setting').length,2,
   'a completed save must release the sample setting lock');
+// The sample reset is a real Framey modal: Cancel cannot write, OK writes the
+// sample setting only after explicit confirmation.
+const reset=content.children[0][2].children[0];
+const setCalls=()=>calls.filter(call=>call.method==='set_setting');
+const dialog=()=>roots.get(elements.get('framey-modal')).value[0].children[1];
+reset.props.onClick();
+reset.props.onClick();
+assert.equal(roots.get(elements.get('framey-modal')).value.length,1,
+  'a rapid second tap must not stack reset dialogs');
+assert.equal(dialog().props.strTitle,'Reset example setting?');
+let rendered=dialog().type(dialog().props);
+rendered.children.find(child=>child?.children?.[0]==='Keep setting').props.onClick();
+await new Promise(resolve=>setImmediate(resolve));
+assert.equal(setCalls().length,2,'cancel leaves the saved value untouched');
+assert.equal(roots.get(elements.get('framey-modal')).value,null);
+reset.props.onClick();
+rendered=dialog().type(dialog().props);
+rendered.children.find(child=>child?.children?.[0]==='Reset').props.onClick();
+await new Promise(resolve=>setImmediate(resolve));
+assert.equal(setCalls().length,3);
+assert.deepEqual(Array.from(setCalls().at(-1).args),['enabled',false]);
+assert.equal(roots.get(elements.get('framey-modal')).value,null);
 assert.equal(window.DFL.Navigation.Navigate('/framey-sample/details/saved-setting'),true);
 assert.equal(window.DFL.useParams().topic,'saved-setting');
 assert.equal(window.DFL.Navigation.Navigate('/library/home'),false);

tests/test_framey_sample.py

@@ -1,6 +1,7 @@
 """The author example stores settings as a normal Decky user plugin."""
 import asyncio
 import importlib.util
+import json
 from pathlib import Path
 import subprocess
 import sys
@@ -36,7 +37,8 @@ class SamplePlugin(unittest.TestCase):
             self.assertTrue(asyncio.run(first.set_setting('enabled', True)))
             second = backend(folder)
             self.assertTrue(asyncio.run(second.get_setting('enabled', False)))
-            self.assertTrue((Path(folder) / 'settings.json').is_file())
+            self.assertEqual(json.loads((Path(folder) / 'settings.json').read_text()),
+                             {'schema': 1, 'enabled': True})
 
     def test_backend_rejects_unknown_keys_and_non_boolean_values(self):
         with tempfile.TemporaryDirectory() as folder:
@@ -57,6 +59,43 @@ class SamplePlugin(unittest.TestCase):
             self.assertTrue(asyncio.run(plugin.set_setting('enabled', True)))
             self.assertTrue(asyncio.run(backend(folder).get_setting('enabled', False)))
 
+    def test_legacy_boolean_survives_restart_and_migrates_on_save(self):
+        with tempfile.TemporaryDirectory() as folder:
+            path = Path(folder) / 'settings.json'
+            path.write_text('{"enabled": true}\n')
+            self.assertTrue(asyncio.run(backend(folder).get_setting('enabled', False)))
+            self.assertEqual(json.loads(path.read_text()), {'enabled': True},
+                             'Reading must not rewrite a user setting')
+            self.assertTrue(asyncio.run(backend(folder).set_setting('enabled', False)))
+            self.assertEqual(json.loads(path.read_text()), {'schema': 1, 'enabled': False})
+            self.assertFalse(asyncio.run(backend(folder).get_setting('enabled', True)))
+
+    def test_newer_schema_is_preserved_on_read_and_save(self):
+        with tempfile.TemporaryDirectory() as folder:
+            path = Path(folder) / 'settings.json'
+            original = '{"schema": 2, "enabled": true, "future": "keep"}\n'
+            path.write_text(original)
+            plugin = backend(folder)
+            with self.assertRaisesRegex(ValueError, 'unsupported sample version'):
+                asyncio.run(plugin.get_setting('enabled', False))
+            with self.assertRaisesRegex(ValueError, 'unsupported sample version'):
+                asyncio.run(plugin.set_setting('enabled', False))
+            self.assertEqual(path.read_text(), original)
+            self.assertEqual(list(Path(folder).glob('.settings-*')), [])
+
+    def test_failed_atomic_replace_keeps_previous_setting(self):
+        with tempfile.TemporaryDirectory() as folder:
+            path = Path(folder) / 'settings.json'
+            plugin = backend(folder)
+            self.assertTrue(asyncio.run(plugin.set_setting('enabled', True)))
+            previous = path.read_bytes()
+            with patch('os.replace', side_effect=OSError('storage unavailable')):
+                with self.assertRaisesRegex(OSError, 'storage unavailable'):
+                    asyncio.run(plugin.set_setting('enabled', False))
+            self.assertEqual(path.read_bytes(), previous)
+            self.assertEqual(list(Path(folder).glob('.settings-*')), [])
+            self.assertTrue(asyncio.run(backend(folder).get_setting('enabled', False)))
+
 
 if __name__ == '__main__':
     unittest.main()