Pi SDK Migration

Historical compatibility notes for the current provider-neutral engine.

Tars uses the Pi Agent SDK for provider selection, model messages, streaming events, history, and tool execution. Older installations used vendor-specific workspace directories and prompt files.

Automatic migration

During setup, the migration path can:

• move recognized legacy chats into ~/.tars/chats/;
• preserve current durable memory and custom skills;
• remove obsolete provider-specific runtime files after migration;
• install a neutral permission-aware system prompt only when the prompt is missing or matches a recognizable old bundled prompt.

An operator-written ~/.tars/system.md is preserved.

Current paths

Use ~/.tars/config.json and .env for provider configuration and credentials. Skills and extensions live directly in ~/.tars/skills/ and ~/.tars/extensions/; no hidden vendor workspace is part of the current layout.

Back up the installation with tars export before migrating an older machine, then verify model, owner, extension enablement, session, and memory behavior after setup.