---
title: "Append Process Conversation"
method: POST
path: "/api/processes/{process_id}/conversations/{session_id}/append"
---

# Append Process Conversation

`POST /api/processes/{process_id}/conversations/{session_id}/append`

Incremental counterpart to `.../conversations/sync` (phase 3).

The full-sync endpoint re-uploads the WHOLE history every sweep — during a
long turn the owning core re-sends a growing 1-2 MB body every 10s, and the
server re-parses it. This endpoint takes only the messages appended since the
core's last successful push:

    { "base_seq": N, "messages": [...], "meta": {...}, "goal": ..., ... }

`base_seq` is the core's high-water mark — the `last_seq` it believes the
server holds. The contract, keyed on the server's ACTUAL `last_seq`:

  * base_seq == last_seq → append all `messages` (the happy path).
  * base_seq <  last_seq → the leading `last_seq - base_seq` messages were
    already applied (a retry or a core that resumed from a stale cursor);
    drop them and append only the genuine tail. Fully-duplicate → no-op.
    This is what makes the push idempotent under retries.
  * base_seq >  last_seq → the core is AHEAD of us: we are missing messages
    it never delivered, so an append would splice a gap. Refuse with 409
    `need_full`; the core falls back to a full `/sync`.

History stays sourced from `history_json` during rollout, so this rebuilds
the full array (old + fresh) and hands it to the same
`cache_and_broadcast_conversation` the full sync uses — identical dual-write,
`conv_delta` broadcast, figure rewrite and goal handling. The saving is on
the WIRE (and the server's JSON parse), not yet the blob write (phase 4).

## Path parameters

- `process_id` string, required
- `session_id` string, required

## Headers

- `authorization` string, nullable

## Response `200`

Successful Response

- object

## Other responses

- `422` — Validation Error

---

[API](https://skmtc.dev/omicos/apis/omicos-server.md) · [All operations](https://skmtc.dev/omicos/apis/omicos-server/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/omicos/omicos-server/revisions/a00b94573ffe/schema)