refactor(setup): persist wizard platform selection in setupPreferences

The setup wizard was writing the user's "which platforms does this
project target?" answer into sessionDefaults.platform, conflating UI
memory with a runtime tool-param default. It also relied on
sessionDefaults.simulatorPlatform (an internal cache) to recover the
non-macOS half of multi-platform selections, which silently reverted
[macOS, visionOS] to [macOS, iOS] on re-run.

Move wizard memory to a dedicated top-level setupPreferences.platforms
field. sessionDefaults.platform/simulatorPlatform are no longer touched
by setup; they remain agent-controlled session defaults. The mcp-json
output still seeds XCODEBUILDMCP_PLATFORM for fresh clients, since that
is an explicit env-var bootstrap, not internal state.

Follow-up #366 tracks moving simulatorPlatform out of sessionDefaults.

Author: cameroncooke

src/cli/commands/__tests__/setup.test.ts

@@ -1337,9 +1337,11 @@ sessionDefaults:
 
     const parsed = parseYaml(storedConfig) as {
       sessionDefaults?: Record<string, unknown>;
+      setupPreferences?: { platforms?: string[] };
     };
 
-    expect(parsed.sessionDefaults?.platform).toBe('macOS');
+    expect(parsed.setupPreferences?.platforms).toEqual(['macOS']);
+    expect(parsed.sessionDefaults?.platform).toBeUndefined();
     expect(parsed.sessionDefaults?.simulatorId).toBeUndefined();
     expect(parsed.sessionDefaults?.simulatorName).toBeUndefined();
   });
@@ -1577,7 +1579,12 @@ sessionDefaults:
       sessionDefaults?: Record<string, unknown>;
     };
 
-    expect(parsed.sessionDefaults?.platform).toBe('macOS');
+    expect(
+      (parsed as { setupPreferences?: { platforms?: string[] } }).setupPreferences?.platforms,
+    ).toEqual(['macOS']);
+    // setup intentionally does not touch sessionDefaults.platform (agent-controlled field);
+    // the pre-existing value from the fixture is preserved.
+    expect(parsed.sessionDefaults?.platform).toBe('iOS Simulator');
     expect(parsed.sessionDefaults?.deviceId).toBeUndefined();
     expect(parsed.sessionDefaults?.simulatorId).toBeUndefined();
     expect(parsed.sessionDefaults?.simulatorName).toBeUndefined();
@@ -1648,7 +1655,10 @@ sessionDefaults:
       sessionDefaults?: Record<string, unknown>;
     };
 
-    expect(parsed.sessionDefaults?.platform).toBe('tvOS Simulator');
+    expect(
+      (parsed as { setupPreferences?: { platforms?: string[] } }).setupPreferences?.platforms,
+    ).toEqual(['tvOS']);
+    expect(parsed.sessionDefaults?.platform).toBeUndefined();
     expect(parsed.sessionDefaults?.simulatorId).toBe('TVOS-1');
     expect(parsed.sessionDefaults?.simulatorName).toBe('Apple TV 4K');
   });
@@ -1723,7 +1733,10 @@ sessionDefaults:
       sessionDefaults?: Record<string, unknown>;
     };
 
-    expect(parsed.sessionDefaults?.platform).toBe('watchOS Simulator');
+    expect(
+      (parsed as { setupPreferences?: { platforms?: string[] } }).setupPreferences?.platforms,
+    ).toEqual(['watchOS']);
+    expect(parsed.sessionDefaults?.platform).toBeUndefined();
     expect(parsed.sessionDefaults?.simulatorId).toBe('WATCH-1');
     expect(parsed.sessionDefaults?.simulatorName).toBe('Apple Watch Series 9');
   });
@@ -1793,7 +1806,10 @@ sessionDefaults:
       sessionDefaults?: Record<string, unknown>;
     };
 
-    expect(parsed.sessionDefaults?.platform).toBe('visionOS Simulator');
+    expect(
+      (parsed as { setupPreferences?: { platforms?: string[] } }).setupPreferences?.platforms,
+    ).toEqual(['visionOS']);
+    expect(parsed.sessionDefaults?.platform).toBeUndefined();
     expect(parsed.sessionDefaults?.simulatorId).toBe('XROS-1');
     expect(parsed.sessionDefaults?.simulatorName).toBe('Apple Vision Pro');
   });

src/cli/commands/setup.ts

@@ -182,26 +182,16 @@ function normalizeExistingDefaults(config?: ProjectConfig): {
 function inferPlatformsFromExisting(config?: ProjectConfig): SetupPlatform[] {
   if (!config) return [];
 
-  const platform = config.sessionDefaults?.platform;
-  if (platform != null && SESSION_DEFAULT_TO_SETUP_PLATFORM[platform] != null) {
-    return [SESSION_DEFAULT_TO_SETUP_PLATFORM[platform]];
+  const stored = config.setupPreferences?.platforms;
+  if (stored && stored.length > 0) {
+    return [...stored];
   }
 
-  // Multi-platform or legacy config: macOS is recovered from the workflow set,
-  // the non-macOS component from the cached simulatorPlatform.
-  const results: SetupPlatform[] = [];
+  // No stored preference: only macOS is unambiguously recoverable from enabledWorkflows.
+  // Simulator-platform identity (iOS vs tvOS vs watchOS vs visionOS) cannot be inferred
+  // from workflow ids alone, so leave it blank and let the wizard re-prompt.
   const workflows = new Set(config.enabledWorkflows ?? []);
-  if (workflows.has('macos')) results.push('macOS');
-
-  const simPlatform = config.sessionDefaults?.simulatorPlatform;
-  const fromSim = simPlatform != null ? SESSION_DEFAULT_TO_SETUP_PLATFORM[simPlatform] : undefined;
-  if (fromSim != null && fromSim !== 'macOS') {
-    results.push(fromSim);
-  } else if (workflows.has('simulator')) {
-    results.push('iOS');
-  }
-
-  return results;
+  return workflows.has('macos') ? ['macOS'] : [];
 }
 
 function derivePlatformSessionDefault(platforms: SetupPlatform[]): string | undefined {
@@ -347,9 +337,9 @@ function getChangedFields(
       afterValue: afterDefaults.simulatorName,
     },
     {
-      label: 'sessionDefaults.platform',
-      beforeValue: beforeDefaults.platform,
-      afterValue: afterDefaults.platform,
+      label: 'setupPreferences.platforms',
+      beforeValue: beforeConfig?.setupPreferences?.platforms,
+      afterValue: afterConfig.setupPreferences?.platforms,
     },
   ];
 
@@ -1113,11 +1103,6 @@ export async function runSetupWizard(deps?: Partial<SetupDependencies>): Promise
     deleteSessionDefaultKeys.push('simulatorId', 'simulatorName');
   }
 
-  const derivedPlatform = derivePlatformSessionDefault(selection.platforms);
-  if (!derivedPlatform) {
-    deleteSessionDefaultKeys.push('platform');
-  }
-
   const persistedProjectPath =
     selection.projectPath != null
       ? relativePathOrAbsolute(selection.projectPath, resolvedDeps.cwd)
@@ -1141,8 +1126,9 @@ export async function runSetupWizard(deps?: Partial<SetupDependencies>): Promise
         deviceId: selection.deviceId,
         simulatorId: selection.simulatorId,
         simulatorName: selection.simulatorName,
-        platform: derivedPlatform,
       },
+      setupPreferences:
+        selection.platforms.length > 0 ? { platforms: [...selection.platforms] } : null,
     },
     deleteSessionDefaultKeys,
   });

src/utils/project-config.ts

@@ -46,6 +46,10 @@ export type PersistActiveSessionDefaultsProfileOptions = {
   profile?: string | null;
 };
 
+export type SetupPreferences = {
+  platforms?: ('macOS' | 'iOS' | 'tvOS' | 'watchOS' | 'visionOS')[];
+};
+
 export type PersistProjectConfigPatchOptions = {
   fs: FileSystemExecutor;
   cwd: string;
@@ -56,6 +60,7 @@ export type PersistProjectConfigPatchOptions = {
     experimentalWorkflowDiscovery?: boolean;
     disableSessionDefaults?: boolean;
     sessionDefaults?: Partial<SessionDefaults>;
+    setupPreferences?: SetupPreferences | null;
   };
   deleteSessionDefaultKeys?: (keyof SessionDefaults)[];
 };
@@ -424,6 +429,12 @@ export async function persistProjectConfigPatch(
     nextConfig[key] = value;
   }
 
+  if (options.patch.setupPreferences === null) {
+    delete nextConfig.setupPreferences;
+  } else if (options.patch.setupPreferences !== undefined) {
+    nextConfig.setupPreferences = options.patch.setupPreferences;
+  }
+
   if (options.patch.sessionDefaults) {
     const patch = removeUndefined(options.patch.sessionDefaults as Record<string, unknown>);
     const nextSessionDefaults: Partial<SessionDefaults> = {

src/utils/runtime-config-schema.ts

@@ -25,6 +25,11 @@ export const runtimeConfigFileSchema = z
     sessionDefaults: sessionDefaultsSchema.optional(),
     sessionDefaultsProfiles: z.record(z.string(), sessionDefaultsSchema).optional(),
     activeSessionDefaultsProfile: z.string().optional(),
+    setupPreferences: z
+      .object({
+        platforms: z.array(z.enum(['macOS', 'iOS', 'tvOS', 'watchOS', 'visionOS'])).optional(),
+      })
+      .optional(),
   })
   .passthrough();