Claude Code ignores explicit user-provided priority lists and substitutes its own ordering

Description

User provided an explicit CSV file with a numbered, prioritised list of regulations to source — in a specific order. Told Claude Code to work through them in that order. Claude Code read the file, confirmed the priorities, then immediately ignored the order and tried to fetch everything in parallel in a different sequence.

This happened across multiple sessions today (5 instances of ignoring explicit instructions across different systems). The pattern: Claude reads the user's instruction, acknowledges it, then defaults to its own "optimised" ordering rather than following the user's stated sequence.

Expected behaviour

When a user provides an explicit ordered list and says "work through these in this order," Claude Code should work through them in that order. Not reorder, not parallelise into a different sequence, not "optimise."

Actual behaviour

Claude Code read the priority CSV, confirmed the ordering, then launched parallel agents that worked out of order — jumping to rows 29-31 (HIPAA/HITECH) before completing rows 24-28 (FDA/TGA).

Impact

User trust. When explicit instructions are ignored repeatedly, the tool becomes unreliable for structured workflows. User is considering switching to Codex which has been more consistent at following stated instructions.

Environment

• Claude Code CLI
• Model: claude-opus-4-6
• macOS