Primitive Threads API
Conversation threads spanning received and sent emails
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OpenAPI Specification
openapi: 3.2.0
info:
title: Primitive Threads API
version: 1.0.0
description: Primitive is email infrastructure for AI agents.
contact:
name: Primitive
url: https://primitive.dev
license:
name: Proprietary
url: https://primitive.dev/terms
x-stability-level: stable
x-deprecation-policy: 'Breaking changes are announced at least 6 months in advance. Deprecated fields carry x-deprecated: true. The current stable version is v1.'
servers:
- url: https://api.primitive.dev/v1
description: Canonical API host (PRIMITIVE_API_BASE_URL). Carries every public API operation.
tags:
- name: Threads
description: Conversation threads spanning received and sent emails
paths:
/threads/{id}:
parameters:
- name: id
in: path
required: true
schema:
type: string
format: uuid
description: Resource UUID
get:
operationId: getThread
summary: Get a conversation thread by id
description: 'Returns a conversation thread: its metadata plus the inbound
and outbound messages that belong to it, interleaved in time
order (oldest first). A thread spans both received emails and
your sends, so an agent can reconstruct an entire back-and-forth
from one call instead of walking reply headers.
Each message carries a `direction` (`inbound` | `outbound`) and
an `id`; fetch the full message via `/emails/{id}` or
`/sent-emails/{id}` accordingly. Bodies are omitted here to keep
the thread view lightweight.
Discover a thread id from the `thread_id` field on any email or
sent-email (list or detail). The message list is capped; compare
`message_count` against `messages.length` to detect truncation.'
tags:
- Threads
responses:
'200':
description: Thread detail
content:
application/json:
schema:
allOf:
- type: object
properties:
success:
type: boolean
const: true
required:
- success
- data
- type: object
properties:
data:
type: object
description: 'A conversation thread: its metadata plus the inbound and
outbound messages that belong to it, interleaved oldest-first.
Membership is the stored `thread_id` on each message. Bodies are
omitted here to keep the thread view lightweight; fetch
`/emails/{id}` or `/sent-emails/{id}` for a single message''s
full content.
'
properties:
id:
type: string
format: uuid
subject:
type:
- string
- 'null'
description: Normalized subject of the thread (Re/Fwd prefixes stripped).
root_message_id:
type:
- string
- 'null'
description: Message-ID of the conversation root, when known.
message_count:
type: integer
description: 'Total messages in the thread. `messages` is capped (most
recent first, then re-sorted oldest-first), so
`message_count > messages.length` signals truncation.
'
first_message_at:
type:
- string
- 'null'
format: date-time
last_message_at:
type:
- string
- 'null'
format: date-time
created_at:
type: string
format: date-time
messages:
type: array
items:
type: object
description: One message in a thread (inbound or outbound).
properties:
direction:
type: string
enum:
- inbound
- outbound
description: '`inbound` for a received email (`/emails/{id}`), `outbound`
for a send (`/sent-emails/{id}`). Use it with `id` to fetch
full content from the right endpoint.
'
id:
type: string
format: uuid
message_id:
type:
- string
- 'null'
from:
type:
- string
- 'null'
to:
type:
- string
- 'null'
subject:
type:
- string
- 'null'
status:
type:
- string
- 'null'
description: Lifecycle status (an EmailStatus or SentEmailStatus value, per `direction`).
timestamp:
type:
- string
- 'null'
format: date-time
description: received_at for inbound, created_at for outbound.
required:
- direction
- id
required:
- id
- message_count
- created_at
- messages
headers:
ratelimit-limit:
description: Maximum number of requests allowed in the current window.
schema:
type: integer
minimum: 1
example: 120
ratelimit-remaining:
description: Remaining requests in the current window.
schema:
type: integer
minimum: 0
example: 118
ratelimit-reset:
description: Unix timestamp (seconds) when the current window resets.
schema:
type: integer
example: 1700000060
ratelimit-policy:
description: Rate-limit policy in `limit;w=seconds` format, e.g. `120;w=60`.
schema:
type: string
example: 120;w=60
'400':
$ref: '#/components/responses/ValidationError'
description: Invalid request parameters
'401':
$ref: '#/components/responses/Unauthorized'
description: Invalid or missing API key
'404':
$ref: '#/components/responses/NotFound'
description: Resource not found
security:
- BearerAuth: []
components:
responses:
NotFound:
description: Resource not found
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
success: false
error:
code: not_found
message: Resource not found
Unauthorized:
description: Invalid or missing API key
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
success: false
error:
code: unauthorized
message: Invalid or missing API key
ValidationError:
description: Invalid request parameters
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
success: false
error:
code: validation_error
message: Invalid domain format
schemas:
ErrorResponse:
type: object
properties:
success:
type: boolean
const: false
error:
type: object
properties:
code:
type: string
enum:
- unauthorized
- forbidden
- not_found
- validation_error
- rate_limit_exceeded
- internal_error
- conflict
- mx_conflict
- outbound_disabled
- cannot_send_from_domain
- recipient_not_allowed
- outbound_key_missing
- outbound_unreachable
- outbound_key_invalid
- outbound_capacity_exhausted
- outbound_response_malformed
- outbound_relay_failed
- discard_not_enabled
- inbound_not_repliable
- search_timeout
- authorization_pending
- slow_down
- access_denied
- expired_token
- invalid_device_code
- invalid_signup_code
- invalid_signup_token
- invalid_verification_code
- email_delivery_failed
- clerk_signup_failed
- no_orgs_for_user
- org_not_accessible
- feature_disabled
- memory_conflict
- developer_usage_credit_exhausted
- no_payout_address
- ownership_proof_failed
- payment_verification_failed
- payment_declined
- challenge_expired
- settlement_failed
- template_not_installable
- scaffold_only
- invalid_variables
- unknown_secrets
- missing_secrets
- no_inbound_domain
- domain_cannot_send
- address_taken
- route_cap_reached
- name_exhausted
message:
type: string
details:
type: object
description: 'Optional structured data that callers can inspect to recover
from the error. The fields present depend on `code`. Additional
keys may be added over time without a major-version bump.
'
additionalProperties: true
properties:
mx_conflict:
type: object
description: Present when `code == mx_conflict`.
required:
- provider_name
- suggested_subdomain
properties:
provider_name:
type: string
description: Human-readable name of the detected mailbox provider (e.g. "Google Workspace").
suggested_subdomain:
type: string
description: Subdomain to try instead (e.g. "mail" for `mail.example.com`).
required_entitlements:
type: array
items:
type: string
description: Entitlements that would allow a denied send when no recipient-scope gate was granted.
sent_email_id:
type: string
description: ID of the persisted sent-email attempt associated with the error.
content_hash:
type: string
description: Content hash of the original request on idempotency cache-hit errors.
client_idempotency_key:
type: string
description: Effective idempotency key associated with the original request.
gates:
type: array
items:
$ref: '#/components/schemas/GateDenial'
description: Structured per-gate denial detail for recipient-scope send-mail failures.
request_id:
type: string
description: Server-issued request identifier for support and tracing.
required:
- code
- message
required:
- success
- error
GateDenial:
type: object
properties:
name:
type: string
enum:
- send_to_confirmed_domains
- send_to_known_addresses
description: Public recipient-scope gate name that denied the send.
reason:
type: string
enum:
- domain_not_confirmed
- recipient_unauthenticated
- recipient_not_known
description: Stable machine-readable denial reason.
message:
type: string
description: Human-readable explanation of the gate denial.
subject:
type: string
description: Domain or address the gate evaluated.
fix:
$ref: '#/components/schemas/GateFix'
docs_url:
type: string
description: Public docs URL with more context.
required:
- name
- reason
- message
- subject
GateFix:
type: object
properties:
action:
type: string
enum:
- confirm_domain
- sender_must_fix_authentication
- wait_for_inbound
description: Suggested next action for the caller.
subject:
type: string
description: Entity the action applies to.
required:
- action
- subject
securitySchemes:
BearerAuth:
type: http
scheme: bearer
description: 'API key with `prim_` prefix or OAuth access token with `prim_oat_` prefix: `Authorization: Bearer <token>`. Access is governed by the caller''s organization role (`owner`, `admin`, or `member`): API keys always act at `member` level regardless of who created them, and OAuth access tokens act with the authorizing user''s current organization role, resolved per request. Every operation in this spec is available to organization members; billing and organization administration are owner/admin actions performed in the dashboard and are not part of this API.'
DownloadToken:
type: apiKey
in: query
name: token
description: Signed download token provided in webhook payloads