---
title: "Write Path"
url: "https://control.actana.ai/docs/architecture/write-path"
description: "Mutations are core-link frames, not REST; the Core owns every task-shaped fact and the Panel stores almost nothing."
updated: 2026-09-01T09:02:52+00:00
---

The **Core** is the source of truth for every project, task, session, pin, and session icon on that machine. It opens its own SQLite read-write and applies mutations itself. The Panel is a connection broker, not a data store.

Mutations travel as **core-link frames** (`projectsMutate`, `tasksMutate`, and the rest of that set). They are not REST. There is no `POST /api/projects/:id/tasks`. That HTTP task API is retired; it does not exist. Third parties write with [`@actana/sdk`](/docs/reference/sdk).

A project's `path` is a machine path on the Core. Only that Core can `stat` it. The Panel sends a candidate path; the Core rejects it if it is not absolute, not resolvable, or a file. The Panel never sees the Core's filesystem.

## What the Panel stores

Two things:

- the **Core registry** — endpoints, sealed pairing credentials, aliases
- one **`lastEventId`** per Core — the event cursor for replay

Nothing task-shaped lives here. Titles, session icons, pin flags, remembered session settings: Core facts, patched over the core link, identical for every Panel connected to that Core. Offline Cores show as unreachable plus last-seen, with no cached rows.

The Fleet view fans out live `tasks.list` calls and merges by `coreId/taskId`. It is an aggregate, not a cache. Cross-Core views are eventual parallel queries, never one SQL statement on the Panel.

## Events

Each mutation appends to the same monotonic event log the PTY lifecycle uses (`project:created`, `task:updated`, and so on). A reconnecting client learns about writes via `lastEventId` replay. No separate event channel.

A Core client sends a starting prompt as text and sends no timing with it. Prompt delivery — when to write, which dialog to answer, when the carriage return goes out — is the Core's, end to end.

## See also

- [Architecture](/docs/architecture) — Panel vs Core.
- [Core link](/docs/architecture/core-link) — the frames those mutations ride.
- [HTTP surfaces](/docs/reference/http-surfaces) — three HTTP surfaces, none a public write API.
- [SDK](/docs/reference/sdk) — `CoreClient` / `CoreSession` for programmatic writes.