docs/WorkflowGuidelines.md: add rule about typeof

docs/WorkflowGuidelines.md

@@ -306,6 +306,35 @@
         ```typescript
         const inputs = Array.from(tableCell.children);
         ```
+
+        * Avoid using `typeof` operator in TypeScript, prefer using explicit types. An exception to this rule is when type in question is a big type nested inside other type.
+
+        Example (with bad practice):
+        ```typescript
+        export const PpqPlugin: Plugin = async ({ client }) => {
+            return {
+                async config(config) {
+                    const provider: typeof config.provider = config.provider;
+                    // ...
+                }
+            }
+        }
+        ```
+
+        Improved code:
+        ```typescript
+        // import relevant type
+        import type { ProviderConfig } from "@opencode-ai/sdk";
+
+        export const PpqPlugin: Plugin = async ({ client }) => {
+            return {
+                async config(config) {
+                    const provider: Record<string, ProviderConfig> = config.provider;
+                    // ...
+                }
+            }
+        }
+        ```
 
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