# List agent messages

`GET /api/v1/agent-messages`

Every agent message in the store, newest first, each carrying the conversation it belongs to. THIS IS THE BATCH TRANSCRIPT READ. Without the filter it is a single paged sweep across ALL conversations, so reconciling a store's chat history is one walk that you group by conversation_id yourself, NOT one request per thread. An audit of this API reported a missing batch route on the assumption that transcripts could only be read one conversation at a time; they cannot, and this is the route that already answers it. ?conversation_id= narrows it to a single thread when that is what you want. An EMPTY value is refused rather than read as "every conversation", because a client building the query from a variable it forgot to set would otherwise receive the whole store's transcript and read it as one thread. PAIR IT WITH GET /api/v1/agent-conversations, which carries the thread's status, assignee and handoff state. This route carries the words; that one carries what the thread IS.

## Query parameters

- `conversation_id` (string) — One conversation's turns. Omit it to read every conversation in the store, which is what this endpoint exists for: the per-conversation transcript was the only way to read messages, so reconciling N conversations cost 1+N requests against a rate budget this whole family shares. An EMPTY value is a 400 rather than "no filter", so a client building the query from a variable it forgot to set does not receive the whole store's transcript and read it as one thread.
- `limit` (integer) — Rows per page. Out of range is a 400 rather than a silent clamp, so a client asking for more than 100 learns it did not get it.
- `after` (string) — The next_cursor from the previous page. Opaque: decode nothing from it and construct nothing by hand, since its encoding is not part of this contract. Omit it to read the first page.

## Responses

- `200` — Success
- `400` — The request was refused before any state changed. `code` is one of:

`invalid_body`, a write body this route will not take. `reason` partitions it
and `field` names the key when one key is at fault.
`invalid_query`, a query parameter, including limit and after.
`invalid_text`, a NUL byte or bytes that are not valid UTF-8 anywhere in the
path, the query or the body. Strip control characters before sending.
`idempotency_key_required`, a write sent without the Idempotency-Key header.
`invalid_request`, an Idempotency-Key longer than 255 bytes.

Routes add their own codes for rules only they know. Switch with a default arm.
- `401` — No credential, or one this API does not accept. `code` is always
`unauthorized`.

THE BODY IS DELIBERATELY UNINFORMATIVE. An expired key, a revoked key, a
publishable key, a key belonging to another merchant and a key that never
existed are all refused with the same bytes, so this response cannot be used to
probe which keys exist. Check the key's state in the dashboard rather than
inferring it here.

Send the key as `Authorization: Bearer <key>` or as `X-API-Key: <key>`. It is
never accepted in a query string.
- `403` — The key lacks the read_sales_agent scope. `code` is `insufficient_scope` and the message names the scope to ask the merchant for.
- `429` — Too many requests. `code` is `rate_limited`.

Two limits apply independently: one on the credential and the route family,
one on the client address. The headers describe whichever has less left, so
honouring Retry-After always clears the window that bound.
- `default` — Any status this operation does not list, in the same envelope.

A 5xx means the request may or may not have applied. Retry it with the SAME
Idempotency-Key: that is the only way to find out without risking a duplicate,
and it is what the key is for.

A few 4xx conditions arrive here rather than as a listed status because they
depend on the merchant's plan or on a module being wired: 402 when a quota or a
plan limit is reached, and 503 when a capability the route needs is not
configured on this deployment. Both carry a `code` naming which.

## Example

```bash
curl --request GET \
  --url 'https://api.mercemur.com/api/v1/agent-messages' \
  --header 'Authorization: Bearer <token>'
```