# `RequestSeal.Adapter.Error`
[🔗](https://github.com/baselabs/request_seal/blob/v0.5.2/lib/request_seal/adapter/error.ex#L1)

Bounded HTTP adapter failures, always nonretryable. `message/1` includes only
the reason and random correlation token; inspection excludes source details.

Closed reasons: `:invalid_options` (missing/unknown/duplicate/invalid choices),
`:invalid_request` (unfaithful or unusable framework value), `:not_final_step` (signing
no longer last), `:cross_origin_redirect` (origin policy),
`:unsupported_delivery` (delivery cannot withhold bytes),
`:unsupported_component` (transport cannot faithfully supply a component),
`:body_unavailable` (required bytes not retained), `:digest_conflict` (caller
digest disagrees), `:limit` (retention/resource bound), `:signing_failed`
(custody or signing rejection), and `:response_rejected` (verification failed).
Plug also reports `:not_captured`, `:already_verified`, `:parser_order`,
`:untrusted_proxy`, and `:request_rejected` (with a bounded core source error).
Plug uses `:unsupported_component` when required or covered exact-target
evidence is unavailable, including target-dependent related-request signing.
`source` is a bounded core, custody, or message error, never a framework exception.

An unexpected exception, throw, or exit inside an adapter stage returns that
stage's fallback reason without source details: `:invalid_options` at
`:attach`, `:invalid_request` at `:capture`, `:signing_failed` at `:sign`, and
`:response_rejected` at `:verify`. Plug `init/1` errors are raised with the
plug's own stage (`:capture`, `:verify`, or `:sign`).

`attempt` counts final signing attempts. Req starts at one and reports a
response error under the attempt that produced it; Finch always uses one.
Plug uses zero for capture, request verification, and option errors, and one
for response signing. Req attach errors use zero.

# `reason`

```elixir
@type reason() ::
  :invalid_options
  | :invalid_request
  | :not_final_step
  | :cross_origin_redirect
  | :unsupported_delivery
  | :unsupported_component
  | :body_unavailable
  | :digest_conflict
  | :limit
  | :signing_failed
  | :response_rejected
  | :not_captured
  | :already_verified
  | :parser_order
  | :untrusted_proxy
  | :request_rejected
```

# `t`

```elixir
@type t() :: %RequestSeal.Adapter.Error{
  __exception__: term(),
  adapter: :req | :finch | :plug,
  attempt: non_neg_integer(),
  correlation: binary(),
  reason: reason(),
  retryable: false,
  source:
    RequestSeal.Error.t()
    | RequestSeal.Custody.Error.t()
    | RequestSeal.Message.Error.t()
    | nil,
  stage: :attach | :capture | :sign | :verify
}
```

# `message`

Returns the reason and the random correlation token, never source details.

## Parameters

  * `error` - a `RequestSeal.Adapter.Error`.

## Returns

  * binary - `"<reason> (<correlation>)"`, where the correlation is 16
    lowercase hexadecimal characters drawn at construction.

## Examples

    iex> {:error, error} = RequestSeal.Finch.request_message(:not_a_finch_request)
    iex> Exception.message(error) =~ ~r/^invalid_request [(][0-9a-f]{16}[)]$/
    true

---

*Consult [api-reference.md](api-reference.md) for complete listing*