Owner's rule. The implementer often cannot know which model it is, so
run-plan.sh derives the name from OPENCODE_MODEL (the part after the
provider), gives the exact trailer and the Model column's value in the
session prompt, and stops the run when a task's commit lacks that exact
line. AGENTS.md replaces the old Implemented-By trailer and the "owner
fills in the model" rule.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>