[Bug] Stale plan file from previous session loaded instead of creating new plan

Bug Description
I just got given a plan for a completely different session:

❯ Where on earth did that plan come from?!                                                                                                                                                                           
                                           
⏺ Ha — that plan file (expressive-splashing-beaver.md) is left over from a previous session. It was the plan for flattening the component library's double-nested src structure (the src/core/src/ → src/core/       
  refactor). Completely unrelated to what we're doing now.                                                                                                                                                           
                                                                                                                                                                                                                     
  I should have overwritten it with a fresh plan or just not entered plan mode at all — the conclusion froussion was "don't do project references, keep path mappings," which doesn't need a plan file.    
                                                                                                                                                                                                                     
  Want me to clean it up, or just leave it?

Environment Info

• Platform: darwin
• Terminal: cursor
• Version: 2.1.63
• Feedback ID: a46429d3-6611-42ca-8bd9-8ac62f80501d

Errors

[{"error":"Error\n    at YM (/$bunfs/root/claude:92:1144)\n    at <anonymous> (/$bunfs/root/claude:93:10067)\n    at emit (node:events:92:22)\n    at endReadableNT (internal:streams/readable:861:50)\n    at processTicksAndRejections (native:7:39)\n    at request (/$bunfs/root/claude:95:2149)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-03-03T14:08:39.930Z"},{"error":"Error\n    at YM (/$bunfs/root/claude:92:1144)\n    at <anonymous> (/$bunfs/root/claude:93:10067)\n    at emit (node:events:92:22)\n    at endReadableNT (internal:streams/readable:861:50)\n    at processTicksAndRejections (native:7:39)\n    at request (/$bunfs/root/claude:95:2149)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-03-03T14:08:39.931Z"},{"error":"Error\n    at YM (/$bunfs/root/claude:92:1144)\n    at <anonymous> (/$bunfs/root/claude:93:10067)\n    at emit (node:events:92:22)\n    at endReadableNT (internal:streams/readable:861:50)\n    at processTicksAndRejections (native:7:39)\n    at request (/$bunfs/root/claude:95:2149)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-03-03T14:08:39.931Z"},{"error":"Error\n    at YM (/$bunfs/root/claude:92:1144)\n    at <anonymous> (/$bunfs/root/claude:93:10067)\n    at emit (node:events:92:22)\n    at endReadableNT (internal:streams/readable:861:50)\n    at processTicksAndRejections (native:7:39)\n    at request (/$bunfs/root/claude:95:2149)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-03-03T14:08:39.931Z"},{"error":"Error\n    at YM (/$bunfs/root/claude:92:1144)\n    at <anonymous> (/$bunfs/root/claude:93:10067)\n    at emit (node:events:92:22)\n    at endReadableNT (internal:streams/readable:861:50)\n    at processTicksAndRejections (native:7:39)\n    at request (/$bunfs/root/claude:95:2149)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-03-03T14:08:40.470Z"},{"error":"Error\n    at YM (/$bunfs/root/claude:92:1144)\n    at <anonymous> (/$bunfs/root/claude:93:10067)\n    at emit (node:events:92:22)\n    at endReadableNT (internal:streams/readable:861:50)\n    at processTicksAndRejections (native:7:39)\n    at request (/$bunfs/root/claude:95:2149)\n    at processTicksAndRejections (native:7:39)",…

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