The plan is complete. The three root causes are:

1. RC1 (timing) — ORIGINAL_GOAL="$GOAL" in sw-loop.sh:419 may run after init_state(), so the first write_state() call uses an empty ORIGINAL_GOAL, falling back to the already-synthesized GOAL and permanently contaminating the state file
2. RC2 (prompt) — compose_prompt() at loop-iteration.sh:369 uses $GOAL (accumulated) not ORIGINAL_GOAL for the ## Your Goal section
3. RC3 (same-value) — both goal: and original_goal: fields are written with the identical _goal_esc value, so if ORIGINAL_GOAL is contaminated, both fields are permanently stuck in that contaminated state

The fix touches 4 files with surgical changes: hoist the ORIGINAL_GOAL assignment, remove the dangerous lazy bootstrap in write_state(), and collapse compose_prompt()'s stuckness branch to always use ORIGINAL_GOAL.