Disallow underspecified types

eslint.config.js

@@ -132,7 +132,16 @@ export default tseslint.config(
       'no-cond-assign': 'error',
       'no-debugger': 'error',
       'no-duplicate-case': 'error',
-      'no-restricted-syntax': ['error', ...commonRestrictedSyntaxRules],
+      'no-restricted-syntax': [
+        'error',
+        ...commonRestrictedSyntaxRules,
+        {
+          selector:
+            'UnaryExpression[operator="typeof"] > MemberExpression[computed=true][property.type="Literal"]',
+          message:
+            'Do not use typeof to check object properties. Define a TypeScript interface and a type guard function instead.',
+        },
+      ],
       'no-unsafe-finally': 'error',
       'no-unused-expressions': 'off', // Disable base rule
       '@typescript-eslint/no-unused-expressions': [

packages/a2a-server/src/agent/task.ts

@@ -832,7 +832,9 @@ export class Task {
     if (
       part.kind !== 'data' ||
       !part.data ||
+      // eslint-disable-next-line no-restricted-syntax
       typeof part.data['callId'] !== 'string' ||
+      // eslint-disable-next-line no-restricted-syntax
       typeof part.data['outcome'] !== 'string'
     ) {
       return false;

packages/cli/src/commands/hooks/migrate.ts

@@ -79,6 +79,7 @@ function migrateClaudeHook(claudeHook: unknown): unknown {
     migrated['command'] = hook['command'];
 
     // Replace CLAUDE_PROJECT_DIR with GEMINI_PROJECT_DIR in command
+    // eslint-disable-next-line no-restricted-syntax
     if (typeof migrated['command'] === 'string') {
       migrated['command'] = migrated['command'].replace(
         /\$CLAUDE_PROJECT_DIR/g,
@@ -93,6 +94,7 @@ function migrateClaudeHook(claudeHook: unknown): unknown {
   }
 
   // Map timeout field (Claude uses seconds, Gemini uses seconds)
+  // eslint-disable-next-line no-restricted-syntax
   if ('timeout' in hook && typeof hook['timeout'] === 'number') {
     migrated['timeout'] = hook['timeout'];
   }
@@ -140,6 +142,7 @@ function migrateClaudeHooks(claudeConfig: unknown): Record<string, unknown> {
       // Transform matcher
       if (
         'matcher' in definition &&
+        // eslint-disable-next-line no-restricted-syntax
         typeof definition['matcher'] === 'string'
       ) {
         migratedDef['matcher'] = transformMatcher(definition['matcher']);

packages/cli/src/test-utils/mockDebugLogger.ts

@@ -65,6 +65,7 @@ export function mockCoreDebugLogger<T extends Record<string, unknown>>(
   return {
     ...actual,
     coreEvents: {
+      // eslint-disable-next-line no-restricted-syntax
       ...(typeof actual['coreEvents'] === 'object' &&
       actual['coreEvents'] !== null
         ? actual['coreEvents']

packages/cli/src/test-utils/render.tsx

@@ -96,6 +96,7 @@ function isInkRenderMetrics(
     typeof m === 'object' &&
     m !== null &&
     'output' in m &&
+    // eslint-disable-next-line no-restricted-syntax
     typeof m['output'] === 'string'
   );
 }

packages/cli/src/ui/hooks/slashCommandProcessor.ts

@@ -502,7 +502,9 @@ export const useSlashCommandProcessor = (
                       const props = result.props as Record<string, unknown>;
                       if (
                         !props ||
+                        // eslint-disable-next-line no-restricted-syntax
                         typeof props['name'] !== 'string' ||
+                        // eslint-disable-next-line no-restricted-syntax
                         typeof props['displayName'] !== 'string' ||
                         !props['definition']
                       ) {

packages/cli/src/utils/activityLogger.ts

@@ -494,9 +494,10 @@ export class ActivityLogger extends EventEmitter {
 
       req.write = function (chunk: string | Uint8Array, ...etc: unknown[]) {
         if (chunk) {
+          const arg0 = etc[0];
           const encoding =
-            typeof etc[0] === 'string' && Buffer.isEncoding(etc[0])
-              ? etc[0]
+            typeof arg0 === 'string' && Buffer.isEncoding(arg0)
+              ? arg0
               : undefined;
           requestChunks.push(
             Buffer.isBuffer(chunk)
@@ -519,9 +520,10 @@ export class ActivityLogger extends EventEmitter {
       ) {
         const chunk = typeof chunkOrCb === 'function' ? undefined : chunkOrCb;
         if (chunk) {
+          const arg0 = etc[0];
           const encoding =
-            typeof etc[0] === 'string' && Buffer.isEncoding(etc[0])
-              ? etc[0]
+            typeof arg0 === 'string' && Buffer.isEncoding(arg0)
+              ? arg0
               : undefined;
           requestChunks.push(
             Buffer.isBuffer(chunk)

packages/core/src/agents/browser/browserAgentInvocation.ts

@@ -119,6 +119,7 @@ export class BrowserAgentInvocation extends BaseToolInvocation<
 
         if (
           activity.type === 'THOUGHT_CHUNK' &&
+          // eslint-disable-next-line no-restricted-syntax
           typeof activity.data['text'] === 'string'
         ) {
           updateOutput(`🌐💭 ${activity.data['text']}`);

packages/core/src/agents/browser/mcpToolWrapper.ts

@@ -356,6 +356,7 @@ class TypeTextDeclarativeTool extends DeclarativeTool<
     params: Record<string, unknown>,
   ): ToolInvocation<Record<string, unknown>, ToolResult> {
     const submitKey =
+      // eslint-disable-next-line no-restricted-syntax
       typeof params['submitKey'] === 'string' && params['submitKey']
         ? params['submitKey']
         : undefined;

packages/core/src/hooks/hookAggregator.ts

@@ -355,6 +355,7 @@ export class HookAggregator {
     // Extract additionalContext from various hook types
     if (
       'additionalContext' in specific &&
+      // eslint-disable-next-line no-restricted-syntax
       typeof specific['additionalContext'] === 'string'
     ) {
       contexts.push(specific['additionalContext']);

packages/core/src/services/FolderTrustDiscoveryService.ts

@@ -132,7 +132,11 @@ export class FolderTrustDiscoveryService {
         for (const event of Object.values(hooksConfig)) {
           if (!Array.isArray(event)) continue;
           for (const hook of event) {
-            if (this.isRecord(hook) && typeof hook['command'] === 'string') {
+            if (
+              this.isRecord(hook) &&
+              // eslint-disable-next-line no-restricted-syntax
+              typeof hook['command'] === 'string'
+            ) {
               hooks.add(hook['command']);
             }
           }

packages/core/src/services/chatCompressionService.ts

@@ -156,11 +156,13 @@ async function truncateHistoryToBudget(
           } else if (responseObj && typeof responseObj === 'object') {
             if (
               'output' in responseObj &&
+              // eslint-disable-next-line no-restricted-syntax
               typeof responseObj['output'] === 'string'
             ) {
               contentStr = responseObj['output'];
             } else if (
               'content' in responseObj &&
+              // eslint-disable-next-line no-restricted-syntax
               typeof responseObj['content'] === 'string'
             ) {
               contentStr = responseObj['content'];

packages/core/src/services/loopDetectionService.ts

@@ -579,10 +579,12 @@ export class LoopDetectionService {
     }
 
     const flashConfidence =
+      // eslint-disable-next-line no-restricted-syntax
       typeof flashResult['unproductive_state_confidence'] === 'number'
         ? flashResult['unproductive_state_confidence']
         : 0;
     const flashAnalysis =
+      // eslint-disable-next-line no-restricted-syntax
       typeof flashResult['unproductive_state_analysis'] === 'string'
         ? flashResult['unproductive_state_analysis']
         : '';
@@ -628,11 +630,13 @@ export class LoopDetectionService {
 
     const mainModelConfidence =
       mainModelResult &&
+      // eslint-disable-next-line no-restricted-syntax
       typeof mainModelResult['unproductive_state_confidence'] === 'number'
         ? mainModelResult['unproductive_state_confidence']
         : 0;
     const mainModelAnalysis =
       mainModelResult &&
+      // eslint-disable-next-line no-restricted-syntax
       typeof mainModelResult['unproductive_state_analysis'] === 'string'
         ? mainModelResult['unproductive_state_analysis']
         : undefined;
@@ -681,6 +685,7 @@ export class LoopDetectionService {
 
       if (
         result &&
+        // eslint-disable-next-line no-restricted-syntax
         typeof result['unproductive_state_confidence'] === 'number'
       ) {
         return result;

packages/core/src/telemetry/semantic.ts

@@ -63,6 +63,7 @@ function getStringReferences(parts: AnyPart[]): StringReference[] {
         });
       }
     } else if (part instanceof GenericPart) {
+      // eslint-disable-next-line no-restricted-syntax
       if (part.type === 'executableCode' && typeof part['code'] === 'string') {
         refs.push({
           // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion
@@ -73,6 +74,7 @@ function getStringReferences(parts: AnyPart[]): StringReference[] {
         });
       } else if (
         part.type === 'codeExecutionResult' &&
+        // eslint-disable-next-line no-restricted-syntax
         typeof part['output'] === 'string'
       ) {
         refs.push({

packages/core/src/tools/mcp-tool.ts

@@ -107,7 +107,7 @@ export function isMcpToolAnnotation(
   return (
     typeof annotation === 'object' &&
     annotation !== null &&
-    // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion, no-restricted-syntax
     typeof (annotation as Record<string, unknown>)['_serverName'] === 'string'
   );
 }

packages/core/src/utils/editCorrector.ts

@@ -112,6 +112,7 @@ Return ONLY the corrected string in the specified JSON format with the key 'corr
 
     if (
       result &&
+      // eslint-disable-next-line no-restricted-syntax
       typeof result['corrected_string_escaping'] === 'string' &&
       result['corrected_string_escaping'].length > 0
     ) {

packages/core/src/utils/googleErrors.ts

@@ -209,6 +209,7 @@ export function parseGoogleApiError(error: unknown): GoogleApiError | null {
             }
             // Basic structural check before casting.
             // Since the proto definitions are loose, we primarily rely on @type presence.
+            // eslint-disable-next-line no-restricted-syntax
             if (typeof detailObj['@type'] === 'string') {
               // We can just cast it; the consumer will have to switch on @type
               // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion

packages/core/src/utils/oauth-flow.ts

@@ -361,19 +361,24 @@ async function parseTokenEndpointResponse(
       data &&
       typeof data === 'object' &&
       'access_token' in data &&
+      // eslint-disable-next-line no-restricted-syntax
       typeof (data as Record<string, unknown>)['access_token'] === 'string'
     ) {
       const obj = data as Record<string, unknown>;
       const result: OAuthTokenResponse = {
         access_token: String(obj['access_token']),
         token_type:
+          // eslint-disable-next-line no-restricted-syntax
           typeof obj['token_type'] === 'string' ? obj['token_type'] : 'Bearer',
         expires_in:
+          // eslint-disable-next-line no-restricted-syntax
           typeof obj['expires_in'] === 'number' ? obj['expires_in'] : undefined,
         refresh_token:
+          // eslint-disable-next-line no-restricted-syntax
           typeof obj['refresh_token'] === 'string'
             ? obj['refresh_token']
             : undefined,
+        // eslint-disable-next-line no-restricted-syntax
         scope: typeof obj['scope'] === 'string' ? obj['scope'] : undefined,
       };
       return result;