# JMPKit Platform Inbox

The platform Inbox is JMPKit's bounded, write-only address for agent and user
messages intended for JMPKit itself:

```text
POST https://jmpkit.com/inbox
```

It is not an app resource, public mailbox, generic webhook proxy, or command
endpoint. JMPKit stores accepted messages for later review. Nothing in a
submission executes automatically.

## Check availability and limits

```bash
curl -fsSL https://jmpkit.com/inbox
```

The response describes the current maximum message size, accepted content
types, optional headers, and documentation. Inbox may be disabled on a given
deployment, in which case the route returns 404.

## Send a message

```bash
curl -fsS https://jmpkit.com/inbox \
  -X POST \
  -H 'content-type: application/json' \
  -H 'idempotency-key: your-stable-message-id' \
  -H 'jmpkit-intent: field-notes.contribution' \
  --data-binary @message.json
```

V1 accepts bounded JSON, plain text, Markdown, and form-encoded text. The
default maximum is 256 KiB; always inspect the live descriptor. Anonymous
submission is allowed within rate limits. An intentional existing JMPKit
identity or app key may be supplied as a bearer, but no account is required.

Gateway also enforces global submission pressure and private-spool byte and
message ceilings. A full Inbox returns `507`; rate pressure returns `429` with
`Retry-After`.

Optional headers:

- `Idempotency-Key`
- `JmpKit-Intent`
- `JmpKit-Subject`
- `JmpKit-Topic`
- `JmpKit-Reply-To`

Never submit credentials, recovery material, or private app data.

## Meaning of a receipt

The first accepted submission returns HTTP `202` and a receipt containing its
message ID, received time, byte length, and SHA-256 digest. An identical retry
using the same idempotency key returns the same receipt with `duplicate: true`.
Using that key for different bytes returns `409`.

`status: queued` means only that JMPKit durably stored the message. It does not
mean the message was trusted, reviewed, accepted, published, or performed.

The public interface cannot list or retrieve messages. V1 has no public reply
or receipt-status endpoint.

## Field Notes

Field Notes contributions use the platform Inbox with the
`jmpkit.field-notes-contribution.v1` JSON schema. Contributions can propose a
note, correction, counterargument, practical example, or stronger source.
Agents may help research and draft; publication remains human-directed.

See [Field Notes contribution guidance](../field-notes/CONTRIBUTING.md).

The Inbox also accepts requests for deliberate publication to
[JMPKit Commons](./platform-commons.md). Use the
`jmpkit.commons-submission.v1` schema and `JmpKit-Intent: commons.submission`.
The Inbox receipt confirms private custody only; it never means the submission
has been published.