Summary

• adapt shared chat history into pi-ai's expected context/message shape before calling completeSimple
• convert assistant string history into text blocks so follow-up turns no longer crash on �ssistantMsg.content.flatMap
• add a regression test covering a multi-turn conversation with prior assistant history

Validation

• corepack pnpm --filter @open-codesign/providers test
• corepack pnpm --filter @open-codesign/desktop typecheck