The re-entry system prompt led with "Read the existing plan" and its
"different task -> overwrite it" step contradicted the planExists guidance
("leave that plan in place and start a fresh file"). Weak models fixated on
reconciling the incomplete old plan and dropped the new request entirely.
- Rewrote the Re-entry procedure in plan-mode-active.md to treat the new
request as the primary input and the old plan as reference only, and to
fold corrections for unfinished old work INTO the new plan rather than
substituting them for the new request.
- Aligned the "different task" branch with the planExists section (fresh
file, no overwrite), removing the contradiction.
- Added reentry-prompt.test.ts asserting the anchoring contract and the
absence of the contradiction.
Fixes#5576
roboomp
faf4890b08