GPT 5.6 doesn't follow instructions.

The past few days a bug came up and I've been trying so long to fix it. But now I've been in a pattern where

"GPT Plans" >> "Codex Executes" >> "GPT Analyzes and says Codex failed" >> "GPT creates new plan" >> "Codex Executes" >> "GPT analyzes and says codex failed again and created new bugs" >> again >> "GPT analyzes and says that codex redid the bug it was supposed to fix"

Its basically executing a thorough plan, throwing it out, and creating it's own rules.

Plan:
all identity fields must be consistent

Codex:
one matching field could be enough

Plan:
placements cannot prove ownership

Codex:
malformed placement data could still influence ownership

Plan:
duplicate placements must work

Codex:
initially treated same sharedVariableId as ambiguity

Plan:
binding changes must persist fully

Codex:
some repair paths were temporary

It was ignoring principles: Source-of-truth, synchronization, TDD/testing.

Anyone know what to do?