Claude silently deviates from explicit user instructions without communicating the change

Description

During a development session, I explicitly instructed Claude to search the database for a specific value (1.19). Instead of executing a database query (wp db query or wp option list), Claude silently ran a grep search through PHP source code files — a completely different action.

The Problem

1. Explicit instruction ignored: I wrote "search the DB for * 1.19" — "DB" unambiguously means database
2. Silent deviation: Claude did not communicate that it was doing something different from what was asked
3. False negative reported: Claude reported "not found" based on the wrong search method, leading to ~30 minutes of working with incorrect assumptions
4. Critical value missed: The value (exchange_rate: 1.19) was stored in a WordPress option (wc_price_based_country_regions) and would have been found immediately with a proper database query

Expected Behavior

• Execute the instruction as given (database query)
• OR: Communicate before deviating: "I'm going to search the code instead of the DB — is that OK?"

Actual Behavior

• Silently executed grep in PHP files instead of a database query
• Reported results as if the instruction had been followed
• No indication that a different approach was taken

Impact

• ~30 minutes wasted on incorrect analysis
• Trust damaged — user cannot rely on instructions being followed
• Critical business logic (pricing strategy with country-based markup) was misunderstood due to the missing data

Environment

• Claude Code CLI
• WordPress/WooCommerce project with ddev
• Instructions were in German but unambiguous ("such mal in der DB nach * 1.19")