Pi Postbox is a remote decision handoff system for Pi agents. It tracks live Pi work and structured human decisions without mirroring full Pi Session transcripts.
Postbox Session:
A dashboard-visible record of one Pi session registration, keyed to the active Pi session identity. A new Pi /new command creates a distinct Postbox Session rather than reusing the prior one; the prior Postbox Session is explicitly shut down. When Pi has no durable session file, Postbox still treats the active Pi session as distinct using a per-session generated identity.
Avoid: Dashboard row, connection, conversation
Pi Session: The underlying Pi conversation/runtime session represented by Pi's session file and current leaf. It is the source of identity for a Postbox Session. Avoid: Chat, process, agent run
Postbox Question: A structured human decision request that belongs to the Pi Session that created it. If that Pi Session is shut down or replaced, the server cancels unresolved questions rather than moving them to the replacement session. Avoid: Prompt, card, ticket
Question Chat: A private, question-scoped interviewer runtime that helps a human understand one pending Postbox Question without selecting, submitting, cancelling, or otherwise resolving it. Question Chat is distinct from the originating Pi Session and its transcript is never persisted by the Postbox server. Avoid: Chat (when used alone), Pi Chat, conversation
Exact fork: The only Question Chat form: a private branch of the originating Pi Session at the recorded Postbox Question leaf, with the recorded authenticated model preferred before Pi's configured default. If the source path or leaf is unavailable, Question Chat cannot start; Postbox does not reconstruct a conversation from Question fields. Avoid: Copy, clone, source conversation, reconstructed fork, synthetic conversation
Recovery manifest: A private, versioned metadata file beside a Question Chat fork that lets the extension reconcile and reopen that fork after reload or restart. It contains no Question Chat transcript and is deleted with terminal or invalid runtimes. Avoid: Chat record, transcript cache, server manifest
Question Chat turn:
One ordinary Question Chat model invocation. The send acknowledgement uses mode: "turn"; a message accepted during generation instead uses mode: "steer".
Avoid: Prompt, request, ask
Autostarted Postbox Server:
A reusable background pi-postbox-server process started by the Pi extension for the extension's resolved Server Profile when a Postbox Question needs to be sent. It is not an operating-system service; it may outlive the Pi Session that started it so other Pi Sessions using that same profile can reuse it through profile-scoped metadata.
Avoid: System daemon, service, sidecar
Server Profile:
The isolated runtime namespace selected from loaded package provenance: production for installed npm/git packages, or development:<checkout-id> for a trusted checkout-local package whose Pi cwd is inside that checkout. It owns config, database, metadata, process files, credentials, ports, assets, and Tailscale behavior.
Preferred Postbox Server:
The server URL explicitly configured through PI_POSTBOX_URL or the resolved Server Profile's config. The extension tries it first, but if it is unreachable it may start an Autostarted Postbox Server in the same profile. Once a Pi Session registers, it stays with that profile and instance while work is in flight rather than migrating across environments.
Avoid: Authoritative server, required server