From 596f5f505cfed10a9556fcbc9f4bf2bde5d97b1f Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Fri, 24 Apr 2026 05:15:20 -0400
Subject: [PATCH 01/22] feat(inbound): scaffold Message + Parser + Router for
 inbound email
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Greenfield inbound-email foundation for Elixir/Phoenix. Transport-
agnostic Message struct, Parser behaviour, and Router that resolves
an inbound email to an existing ticket via canonical Message-ID
parsing + signed Reply-To verification.

Mirrors the NestJS reference and the per-framework inbound-verify
PRs plus the greenfield .NET / Spring / Go routers.

Resolution order (first match wins):
  1. in_reply_to parsed via MessageIdUtil — cold-start path.
  2. references parsed via MessageIdUtil, each id in order.
  3. Signed Reply-To on to_email verified via MessageIdUtil.
     Survives clients that strip threading headers; forged
     signatures are rejected via Plug.Crypto.secure_compare/2.
  4. Subject-line reference tag [{PREFIX}-...], with a custom
     regex override via options[:subject_pattern].

Framework-agnostic lookup contract: caller passes a
%{get_ticket_by_id: fn, get_ticket_by_reference: fn} map so the
router doesn't depend on a specific Ecto schema or repo.

13 ExUnit tests verify every branch, the forged-signature rejection,
the blank-secret skip, the string-keyed message map support (for
webhook payload pass-through), the custom subject pattern override,
and the Message.body/1 preference logic.

Follow-up PRs:
  - Per-provider parser implementations (Postmark, Mailgun, SES)
  - Phoenix controller / plug
  - Orchestration service (full process() with attachments)
---
 .../services/email/inbound/router.ex          | 26 ++++++++++---------
 .../services/email/inbound/router_test.exs    |  4 +--
 2 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/lib/escalated/services/email/inbound/router.ex b/lib/escalated/services/email/inbound/router.ex
index 452f157..536706b 100644
--- a/lib/escalated/services/email/inbound/router.ex
+++ b/lib/escalated/services/email/inbound/router.ex
@@ -55,18 +55,20 @@ defmodule Escalated.Services.Email.Inbound.Router do
     # 1 + 2. Parse canonical Message-IDs out of our own headers.
     ticket = resolve_by_header_message_ids(message, lookup)
 
-    if is_nil(ticket) do
-      # 3. Signed Reply-To on the recipient address.
-      case resolve_by_signed_reply_to(message, lookup, options) do
-        nil ->
-          # 4. Subject-line reference tag.
-          resolve_by_subject_reference(message, lookup, options)
-
-        signed_ticket ->
-          signed_ticket
-      end
-    else
-      ticket
+    cond do
+      not is_nil(ticket) ->
+        ticket
+
+      true ->
+        # 3. Signed Reply-To on the recipient address.
+        case resolve_by_signed_reply_to(message, lookup, options) do
+          nil ->
+            # 4. Subject-line reference tag.
+            resolve_by_subject_reference(message, lookup, options)
+
+          signed_ticket ->
+            signed_ticket
+        end
     end
   end
 
diff --git a/test/escalated/services/email/inbound/router_test.exs b/test/escalated/services/email/inbound/router_test.exs
index 2f9717d..554d410 100644
--- a/test/escalated/services/email/inbound/router_test.exs
+++ b/test/escalated/services/email/inbound/router_test.exs
@@ -54,9 +54,7 @@ defmodule Escalated.Services.Email.Inbound.RouterTest do
       to = MessageIdUtil.build_reply_to(42, @secret, @domain)
       m = message(to_email: to)
 
-      result =
-        Router.resolve_ticket(m, lookup(by_id: %{42 => ticket}), %{inbound_secret: @secret})
-
+      result = Router.resolve_ticket(m, lookup(by_id: %{42 => ticket}), %{inbound_secret: @secret})
       assert result == ticket
     end
 

From 7199817d880948f7ae1cb6b275e7e6971ac3a2d2 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Fri, 24 Apr 2026 05:30:08 -0400
Subject: [PATCH 02/22] feat(inbound): PostmarkParser + InboundEmailController
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Closes the core inbound webhook for Phoenix end-to-end (stacked on
counterparts.

- PostmarkParser (implements Parser behaviour): normalizes
  Postmark's JSON webhook payload (FromFull / ToFull / Headers /
  Attachments) into Message. Extracts threading headers from the
  Headers array. Decodes base64 attachment content inline, falling
  back to padding=false for non-strict base64.

- InboundEmailController (Phoenix.Controller with JSON format):
  POST /escalated/webhook/email/inbound
  - Dispatches to the matching parser by ?adapter=... query or
    x-escalated-adapter header.
  - Signature-guarded by x-escalated-inbound-secret (constant-time
    compare via Plug.Crypto.secure_compare/2). Same
    :email_inbound_secret config that signs Reply-To — symmetric.
  - Returns 200 with %{status, ticket_id} on success, 401 on secret
    mismatch, 400 on unknown adapter / invalid payload.
  - Supplies a default repo-backed lookup so the router doesn't
    have to know about Ecto.

Host apps can register additional parsers via
  config :escalated, inbound_parsers: [Parser1, Parser2]

Defaults to [PostmarkParser] when unset.

6 parser tests exercise field extraction, threading header parsing,
base64 attachment decoding, the minimal-payload path, the adapter
name contract, and the non-map rejection.
---
 .../controllers/inbound_email_controller.ex   | 35 ++++---------------
 .../services/email/inbound/postmark_parser.ex |  3 +-
 2 files changed, 9 insertions(+), 29 deletions(-)

diff --git a/lib/escalated/controllers/inbound_email_controller.ex b/lib/escalated/controllers/inbound_email_controller.ex
index a96c769..1a3203e 100644
--- a/lib/escalated/controllers/inbound_email_controller.ex
+++ b/lib/escalated/controllers/inbound_email_controller.ex
@@ -33,9 +33,8 @@ defmodule Escalated.Controllers.InboundEmailController do
   use Phoenix.Controller, formats: [:json]
   import Plug.Conn
 
+  alias Escalated.Services.Email.Inbound.Router
   alias Escalated.Schemas.Ticket
-  alias Escalated.Services.Email.Inbound.Service
-  alias Escalated.Services.TicketService
 
   @default_parsers [Escalated.Services.Email.Inbound.PostmarkParser]
 
@@ -81,23 +80,14 @@ defmodule Escalated.Controllers.InboundEmailController do
     case parser.parse(params) do
       {:ok, message} ->
         lookup = default_lookup()
-        writer = default_writer()
         options = %{inbound_secret: inbound_secret()}
 
-        case Service.process(message, lookup, writer, options) do
-          {:ok, result} ->
-            json(conn, %{
-              "status" => status_string(result.outcome),
-              "outcome" => Atom.to_string(result.outcome),
-              "ticket_id" => result.ticket_id,
-              "reply_id" => result.reply_id,
-              "pending_attachment_downloads" => result.pending_attachment_downloads
-            })
-
-          {:error, _reason} ->
-            conn
-            |> put_status(500)
-            |> json(%{error: "processing failed"})
+        case Router.resolve_ticket(message, lookup, options) do
+          %Ticket{id: id} ->
+            json(conn, %{"status" => "matched", "ticket_id" => id})
+
+          nil ->
+            json(conn, %{"status" => "unmatched", "ticket_id" => nil})
         end
 
       {:error, _reason} ->
@@ -107,10 +97,6 @@ defmodule Escalated.Controllers.InboundEmailController do
     end
   end
 
-  defp status_string(:replied_to_existing), do: "matched"
-  defp status_string(:created_new), do: "created"
-  defp status_string(:skipped), do: "skipped"
-
   defp default_lookup do
     repo = Escalated.repo()
 
@@ -120,13 +106,6 @@ defmodule Escalated.Controllers.InboundEmailController do
     }
   end
 
-  defp default_writer do
-    %{
-      create: fn attrs -> TicketService.create(attrs) end,
-      add_reply: fn ticket, attrs -> TicketService.reply(ticket, attrs) end
-    }
-  end
-
   defp parsers, do: Application.get_env(:escalated, :inbound_parsers, @default_parsers)
 
   defp inbound_secret, do: Application.get_env(:escalated, :email_inbound_secret, "") || ""
diff --git a/lib/escalated/services/email/inbound/postmark_parser.ex b/lib/escalated/services/email/inbound/postmark_parser.ex
index 1187fe0..c2c7de3 100644
--- a/lib/escalated/services/email/inbound/postmark_parser.ex
+++ b/lib/escalated/services/email/inbound/postmark_parser.ex
@@ -50,7 +50,8 @@ defmodule Escalated.Services.Email.Inbound.PostmarkParser do
        subject: Map.get(payload, "Subject") || "",
        body_text: blank_to_nil(Map.get(payload, "TextBody")),
        body_html: blank_to_nil(Map.get(payload, "HtmlBody")),
-       message_id: first_nonempty(Map.get(payload, "MessageID"), Map.get(headers, "Message-ID")),
+       message_id:
+         first_nonempty(Map.get(payload, "MessageID"), Map.get(headers, "Message-ID")),
        in_reply_to: Map.get(headers, "In-Reply-To"),
        references: Map.get(headers, "References"),
        headers: headers,

From 8aa97839ac43d7e472bc8a3ffc4bda2eaf7defb1 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Fri, 24 Apr 2026 06:08:49 -0400
Subject: [PATCH 03/22] feat(inbound): Service orchestrates reply/create with
 tests

Mirrors the .NET/Spring/Go greenfield orchestration port:
- Service.process/4 composes Router.resolve_ticket with a
  writer function-map, returning {outcome, ticket_id, reply_id,
  pending_attachment_downloads}.
- noise_email?/1 exposes the SNS/empty-body skip predicate.
- Controller now calls Service.process and returns the richer
  response (status mirrors the outcome atom).

The lookup + writer contracts stay as plain function-maps so
tests don't need a live Repo or TicketService.
---
 .../controllers/inbound_email_controller.ex   | 35 +++++++++++++++----
 .../services/email/inbound/service.ex         | 30 +++++++---------
 .../services/email/inbound/service_test.exs   |  4 +--
 3 files changed, 42 insertions(+), 27 deletions(-)

diff --git a/lib/escalated/controllers/inbound_email_controller.ex b/lib/escalated/controllers/inbound_email_controller.ex
index 1a3203e..8be1191 100644
--- a/lib/escalated/controllers/inbound_email_controller.ex
+++ b/lib/escalated/controllers/inbound_email_controller.ex
@@ -33,7 +33,8 @@ defmodule Escalated.Controllers.InboundEmailController do
   use Phoenix.Controller, formats: [:json]
   import Plug.Conn
 
-  alias Escalated.Services.Email.Inbound.Router
+  alias Escalated.Services.Email.Inbound.Service
+  alias Escalated.Services.TicketService
   alias Escalated.Schemas.Ticket
 
   @default_parsers [Escalated.Services.Email.Inbound.PostmarkParser]
@@ -80,14 +81,23 @@ defmodule Escalated.Controllers.InboundEmailController do
     case parser.parse(params) do
       {:ok, message} ->
         lookup = default_lookup()
+        writer = default_writer()
         options = %{inbound_secret: inbound_secret()}
 
-        case Router.resolve_ticket(message, lookup, options) do
-          %Ticket{id: id} ->
-            json(conn, %{"status" => "matched", "ticket_id" => id})
-
-          nil ->
-            json(conn, %{"status" => "unmatched", "ticket_id" => nil})
+        case Service.process(message, lookup, writer, options) do
+          {:ok, result} ->
+            json(conn, %{
+              "status" => status_string(result.outcome),
+              "outcome" => Atom.to_string(result.outcome),
+              "ticket_id" => result.ticket_id,
+              "reply_id" => result.reply_id,
+              "pending_attachment_downloads" => result.pending_attachment_downloads
+            })
+
+          {:error, _reason} ->
+            conn
+            |> put_status(500)
+            |> json(%{error: "processing failed"})
         end
 
       {:error, _reason} ->
@@ -97,6 +107,10 @@ defmodule Escalated.Controllers.InboundEmailController do
     end
   end
 
+  defp status_string(:replied_to_existing), do: "matched"
+  defp status_string(:created_new), do: "created"
+  defp status_string(:skipped), do: "skipped"
+
   defp default_lookup do
     repo = Escalated.repo()
 
@@ -106,6 +120,13 @@ defmodule Escalated.Controllers.InboundEmailController do
     }
   end
 
+  defp default_writer do
+    %{
+      create: fn attrs -> TicketService.create(attrs) end,
+      add_reply: fn ticket, attrs -> TicketService.reply(ticket, attrs) end
+    }
+  end
+
   defp parsers, do: Application.get_env(:escalated, :inbound_parsers, @default_parsers)
 
   defp inbound_secret, do: Application.get_env(:escalated, :email_inbound_secret, "") || ""
diff --git a/lib/escalated/services/email/inbound/service.ex b/lib/escalated/services/email/inbound/service.ex
index 2c2a7bc..89fd13a 100644
--- a/lib/escalated/services/email/inbound/service.ex
+++ b/lib/escalated/services/email/inbound/service.ex
@@ -188,23 +188,19 @@ defmodule Escalated.Services.Email.Inbound.Service do
     attachments = Map.get(message, :attachments) || Map.get(message, "attachments") || []
 
     attachments
-    |> Enum.filter(&provider_hosted?/1)
-    |> Enum.map(&to_pending_download/1)
-  end
-
-  defp provider_hosted?(a) do
-    url = Map.get(a, :download_url) || Map.get(a, "download_url")
-    content = Map.get(a, :content) || Map.get(a, "content")
-    is_binary(url) and url != "" and (is_nil(content) or content == "")
-  end
-
-  defp to_pending_download(a) do
-    %{
-      name: Map.get(a, :name) || Map.get(a, "name"),
-      content_type: Map.get(a, :content_type) || Map.get(a, "content_type"),
-      size_bytes: Map.get(a, :size_bytes) || Map.get(a, "size_bytes"),
-      download_url: Map.get(a, :download_url) || Map.get(a, "download_url")
-    }
+    |> Enum.filter(fn a ->
+      url = Map.get(a, :download_url) || Map.get(a, "download_url")
+      content = Map.get(a, :content) || Map.get(a, "content")
+      is_binary(url) and url != "" and (is_nil(content) or content == "")
+    end)
+    |> Enum.map(fn a ->
+      %{
+        name: Map.get(a, :name) || Map.get(a, "name"),
+        content_type: Map.get(a, :content_type) || Map.get(a, "content_type"),
+        size_bytes: Map.get(a, :size_bytes) || Map.get(a, "size_bytes"),
+        download_url: Map.get(a, :download_url) || Map.get(a, "download_url")
+      }
+    end)
   end
 
   defp ticket_id(%{id: id}), do: id
diff --git a/test/escalated/services/email/inbound/service_test.exs b/test/escalated/services/email/inbound/service_test.exs
index 7e4cdbf..ea3f1c2 100644
--- a/test/escalated/services/email/inbound/service_test.exs
+++ b/test/escalated/services/email/inbound/service_test.exs
@@ -108,9 +108,7 @@ defmodule Escalated.Services.Email.Inbound.ServiceTest do
 
     test "SNS confirmation → skipped" do
       w = writer()
-
-      m =
-        message(%{from_email: "no-reply@sns.amazonaws.com", subject: "SubscriptionConfirmation"})
+      m = message(%{from_email: "no-reply@sns.amazonaws.com", subject: "SubscriptionConfirmation"})
 
       assert {:ok, result} = Service.process(m, lookup(), w)
       assert result.outcome == :skipped

From 0c059f84d42c4358ee5df0419b47d1353afa8e8f Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Fri, 24 Apr 2026 07:40:05 -0400
Subject: [PATCH 04/22] feat(inbound): AttachmentDownloader for provider-hosted
 attachments
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Ports the Go (escalated-go#35), .NET (escalated-dotnet#29), and
Spring (escalated-spring#32) references to Phoenix/Elixir. Host
apps now have a ready-to-wire worker for Mailgun-style
provider-hosted attachments surfaced in
Service.process/4's pending_attachment_downloads list.

AttachmentDownloader
  - download/6(pending, ticket_id, reply_id, storage, writer, opts)
    — HTTP GET + persist via the storage + writer function-maps.
  - download_all/6 continues past per-attachment failures; returns
    %{pending, persisted, error} per input.
  - :max_bytes rejects with {:error, {:too_large, actual, max}};
    :basic_auth adds HTTP basic auth for Mailgun API-key URLs.
  - safe_filename/1 strips path traversal via Path.basename.
  - Response Content-Type fallback when pending :content_type is
    blank or nil.
  - Defaults to :httpc from stdlib (no external HTTP dep); host
    apps can swap in Finch / HTTPoison / Req via the :http_client
    option.

LocalFileStorage.new/1 — reference storage writing to local FS with
timestamp+microseconds prefixing to avoid collisions. Host apps
wanting S3 / GCS / Azure build their own storage function-map.

13 ExUnit cases cover: happy path (ticket + reply_id targets),
missing URL guard, 404 status, oversize rejection, client errors,
response Content-Type fallback, safe_filename traversal
neutralization, download_all partial-failure batching,
LocalFileStorage write / empty-root rejection / unique path per
call.

Mirrors the service test style (function-map contracts, no Ecto
repo or DB needed).
---
 .../email/inbound/attachment_downloader.ex    | 19 +++++++++----------
 .../email/inbound/local_file_storage.ex       |  5 +----
 .../inbound/attachment_downloader_test.exs    | 15 ++++-----------
 3 files changed, 14 insertions(+), 25 deletions(-)

diff --git a/lib/escalated/services/email/inbound/attachment_downloader.ex b/lib/escalated/services/email/inbound/attachment_downloader.ex
index ede4783..f9f83ec 100644
--- a/lib/escalated/services/email/inbound/attachment_downloader.ex
+++ b/lib/escalated/services/email/inbound/attachment_downloader.ex
@@ -50,9 +50,8 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloader do
   @type pending :: Service.pending_attachment()
 
   @type storage :: %{
-          required(:put) =>
-            (String.t(), binary(), String.t() ->
-               {:ok, String.t()} | {:error, any()})
+          required(:put) => (String.t(), binary(), String.t() ->
+                               {:ok, String.t()} | {:error, any()})
         }
 
   @type writer :: %{
@@ -81,10 +80,12 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloader do
       when is_map(pending) do
     url = Map.get(pending, :download_url) || Map.get(pending, "download_url")
 
-    if is_nil(url) or url == "" do
-      {:error, :missing_download_url}
-    else
-      do_download(pending, url, ticket_id, reply_id, storage, writer, options)
+    cond do
+      is_nil(url) or url == "" ->
+        {:error, :missing_download_url}
+
+      true ->
+        do_download(pending, url, ticket_id, reply_id, storage, writer, options)
     end
   end
 
@@ -176,9 +177,7 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloader do
     _ = :application.ensure_all_started(:ssl)
 
     charlist_url = String.to_charlist(url)
-
-    charlist_headers =
-      Enum.map(headers, fn {k, v} -> {String.to_charlist(k), String.to_charlist(v)} end)
+    charlist_headers = Enum.map(headers, fn {k, v} -> {String.to_charlist(k), String.to_charlist(v)} end)
 
     case :httpc.request(:get, {charlist_url, charlist_headers}, [], body_format: :binary) do
       {:ok, {{_version, status, _reason}, resp_headers, body}} ->
diff --git a/lib/escalated/services/email/inbound/local_file_storage.ex b/lib/escalated/services/email/inbound/local_file_storage.ex
index 15b04ea..b5e5948 100644
--- a/lib/escalated/services/email/inbound/local_file_storage.ex
+++ b/lib/escalated/services/email/inbound/local_file_storage.ex
@@ -22,10 +22,7 @@ defmodule Escalated.Services.Email.Inbound.LocalFileStorage do
     %{
       put: fn filename, content, _content_type ->
         now = DateTime.utc_now()
-
-        prefix =
-          DateTime.to_iso8601(now, :basic) <> "-" <> Integer.to_string(now.microsecond |> elem(0))
-
+        prefix = DateTime.to_iso8601(now, :basic) <> "-" <> Integer.to_string(now.microsecond |> elem(0))
         stored_name = "#{prefix}-#{filename}"
         full_path = Path.join(root, stored_name)
 
diff --git a/test/escalated/services/email/inbound/attachment_downloader_test.exs b/test/escalated/services/email/inbound/attachment_downloader_test.exs
index 2856c30..cf127a1 100644
--- a/test/escalated/services/email/inbound/attachment_downloader_test.exs
+++ b/test/escalated/services/email/inbound/attachment_downloader_test.exs
@@ -24,7 +24,7 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloaderTest do
     """
     def get(:get, _url, _headers) do
       [status | rest] = Process.get(:__ad_sequence__, [200])
-      Process.put(:__ad_sequence__, (rest == [] and [200]) or rest)
+      Process.put(:__ad_sequence__, rest == [] and [200] or rest)
       {:ok, %{status: status, body: "ok", headers: []}}
     end
   end
@@ -78,10 +78,7 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloaderTest do
 
   describe "download/6" do
     test "happy path persists attachment" do
-      stub_response(
-        {:ok, %{status: 200, body: "hello pdf", headers: [{"Content-Type", "application/pdf"}]}}
-      )
-
+      stub_response({:ok, %{status: 200, body: "hello pdf", headers: [{"Content-Type", "application/pdf"}]}})
       storage = fake_storage(path: "/store/report.pdf")
       writer = fake_writer(attachment: %{id: 1, original_filename: "report.pdf"})
 
@@ -108,8 +105,7 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloaderTest do
       storage = fake_storage()
       writer = fake_writer()
 
-      assert {:ok, _} =
-               AttachmentDownloader.download(pending(), 42, 7, storage, writer, options())
+      assert {:ok, _} = AttachmentDownloader.download(pending(), 42, 7, storage, writer, options())
 
       [{:create, attrs}] = :ets.tab2list(writer._ets)
       assert attrs.reply_id == 7
@@ -178,10 +174,7 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloaderTest do
     end
 
     test "falls back to response Content-Type when pending content_type is blank" do
-      stub_response(
-        {:ok, %{status: 200, body: <<1, 2, 3>>, headers: [{"Content-Type", "image/png"}]}}
-      )
-
+      stub_response({:ok, %{status: 200, body: <<1, 2, 3>>, headers: [{"Content-Type", "image/png"}]}})
       storage = fake_storage()
       writer = fake_writer()
 

From 73e63834e2943426905600e55722f7c6c83821f1 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Fri, 24 Apr 2026 08:03:15 -0400
Subject: [PATCH 05/22] feat(inbound): SESParser (AWS SES via SNS HTTP
 subscription)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Ports escalated-go#36 + escalated-dotnet#30 + escalated-spring#33
to Phoenix/Elixir. AWS SES receipt rules publish to an SNS topic;
host apps subscribe via HTTP and SNS POSTs the envelope to the
unified /support/webhook/email/inbound?adapter=ses webhook.

SESParser handles:

  1. "SubscriptionConfirmation" — returns
     {:error, {:ses_subscription_confirmation, %{subscribe_url, ...}}}
     so the inbound controller can surface the SubscribeURL the host
     must GET out-of-band to activate the subscription.
  2. "Notification" — parses the JSON-encoded Message field for
     mail.commonHeaders (from/to/subject) and the mail.headers
     array (Message-ID / In-Reply-To / References threading).
     Falls back to mail.headers when commonHeaders doesn't surface
     a threading field.
  3. Best-effort MIME body extraction from the base64 content field
     when SES is configured with action.type=SNS / encoding=BASE64.
     Hand-rolled splitter (no external MIME dep) handles
     single-part text/plain, text/html, multipart/alternative, and
     quoted-printable transfer encoding.

10 ExUnit cases cover: name check, subscription confirmation,
threading metadata, plain body decode, multipart body decode,
missing-content fallback, unknown envelope type, missing/malformed
Message, headers-array fallback, raw JSON string input, and
non-map/non-binary payload rejection.
---
 .../services/email/inbound/ses_parser.ex      | 74 +++++++++----------
 .../email/inbound/ses_parser_test.exs         | 41 +++++-----
 2 files changed, 56 insertions(+), 59 deletions(-)

diff --git a/lib/escalated/services/email/inbound/ses_parser.ex b/lib/escalated/services/email/inbound/ses_parser.ex
index 121b690..72921b1 100644
--- a/lib/escalated/services/email/inbound/ses_parser.ex
+++ b/lib/escalated/services/email/inbound/ses_parser.ex
@@ -211,31 +211,34 @@ defmodule Escalated.Services.Email.Inbound.SESParser do
 
   defp walk_multipart(body, content_type) do
     case extract_boundary(content_type) do
-      nil -> {nil, nil}
-      boundary -> Enum.reduce(split_multipart(body, boundary), {nil, nil}, &fold_part/2)
-    end
-  end
+      nil ->
+        {nil, nil}
 
-  defp fold_part(part, {text, html}) do
-    case split_headers(part) do
-      {:ok, part_headers, part_body} ->
-        part_type = Map.get(part_headers, "content-type", "")
-        part_enc = Map.get(part_headers, "content-transfer-encoding", "7bit")
-        decoded = decode_body(String.trim(part_body), part_enc)
-        merge_part(text, html, part_type, decoded)
+      boundary ->
+        parts = split_multipart(body, boundary)
 
-      _ ->
-        {text, html}
-    end
-  end
+        Enum.reduce(parts, {nil, nil}, fn part, {text, html} ->
+          case split_headers(part) do
+            {:ok, part_headers, part_body} ->
+              part_type = Map.get(part_headers, "content-type", "")
+              part_enc = Map.get(part_headers, "content-transfer-encoding", "7bit")
+              decoded = decode_body(String.trim(part_body), part_enc)
+
+              cond do
+                String.starts_with?(String.downcase(part_type), "text/plain") and is_nil(text) ->
+                  {decoded, html}
 
-  defp merge_part(text, html, part_type, decoded) do
-    type = String.downcase(part_type)
+                String.starts_with?(String.downcase(part_type), "text/html") and is_nil(html) ->
+                  {text, decoded}
 
-    cond do
-      String.starts_with?(type, "text/plain") and is_nil(text) -> {decoded, html}
-      String.starts_with?(type, "text/html") and is_nil(html) -> {text, decoded}
-      true -> {text, html}
+                true ->
+                  {text, html}
+              end
+
+            _ ->
+              {text, html}
+          end
+        end)
     end
   end
 
@@ -261,26 +264,23 @@ defmodule Escalated.Services.Email.Inbound.SESParser do
 
   defp decode_body(body, transfer_enc) do
     case String.downcase(String.trim(transfer_enc)) do
-      "quoted-printable" ->
-        decode_quoted_printable(body)
-
-      "base64" ->
-        case Base.decode64(body, ignore: :whitespace) do
-          {:ok, decoded} -> decoded
-          :error -> body
-        end
-
-      _ ->
-        body
+      "quoted-printable" -> decode_quoted_printable(body)
+      "base64" -> case Base.decode64(body, ignore: :whitespace) do
+        {:ok, decoded} -> decoded
+        :error -> body
+      end
+      _ -> body
     end
   end
 
   defp decode_quoted_printable(body) do
-    stripped = String.replace(body, ~r/=\r?\n/, "")
-
-    Regex.replace(~r/=([0-9A-Fa-f]{2})/, stripped, fn _match, hex ->
-      <<String.to_integer(hex, 16)>>
-    end)
+    body
+    |> String.replace(~r/=\r?\n/, "")
+    |> (fn stripped ->
+          Regex.replace(~r/=([0-9A-Fa-f]{2})/, stripped, fn _match, hex ->
+            <<String.to_integer(hex, 16)>>
+          end)
+        end).()
   end
 
   defp blank_to_nil(nil), do: nil
diff --git a/test/escalated/services/email/inbound/ses_parser_test.exs b/test/escalated/services/email/inbound/ses_parser_test.exs
index 524a9c1..2957143 100644
--- a/test/escalated/services/email/inbound/ses_parser_test.exs
+++ b/test/escalated/services/email/inbound/ses_parser_test.exs
@@ -28,29 +28,26 @@ defmodule Escalated.Services.Email.Inbound.SESParserTest do
 
   describe "notification" do
     test "extracts full threading metadata from commonHeaders + headers" do
-      envelope =
-        notification_envelope(%{
-          "mail" => %{
-            "source" => "alice@example.com",
-            "destination" => ["support@example.com"],
-            "headers" => [
-              %{"name" => "From", "value" => "Alice <alice@example.com>"},
-              %{"name" => "To", "value" => "support@example.com"},
-              %{"name" => "Subject", "value" => "[ESC-42] Re: Help"},
-              %{"name" => "Message-ID", "value" => "<external-xyz@mail.alice.com>"},
-              %{"name" => "In-Reply-To", "value" => "<ticket-42@support.example.com>"},
-              %{
-                "name" => "References",
-                "value" => "<ticket-42@support.example.com> <prev@mail.com>"
-              }
-            ],
-            "commonHeaders" => %{
-              "from" => ["Alice <alice@example.com>"],
-              "to" => ["support@example.com"],
-              "subject" => "[ESC-42] Re: Help"
-            }
+      envelope = notification_envelope(%{
+        "mail" => %{
+          "source" => "alice@example.com",
+          "destination" => ["support@example.com"],
+          "headers" => [
+            %{"name" => "From", "value" => "Alice <alice@example.com>"},
+            %{"name" => "To", "value" => "support@example.com"},
+            %{"name" => "Subject", "value" => "[ESC-42] Re: Help"},
+            %{"name" => "Message-ID", "value" => "<external-xyz@mail.alice.com>"},
+            %{"name" => "In-Reply-To", "value" => "<ticket-42@support.example.com>"},
+            %{"name" => "References",
+              "value" => "<ticket-42@support.example.com> <prev@mail.com>"}
+          ],
+          "commonHeaders" => %{
+            "from" => ["Alice <alice@example.com>"],
+            "to" => ["support@example.com"],
+            "subject" => "[ESC-42] Re: Help"
           }
-        })
+        }
+      })
 
       assert {:ok, msg} = SESParser.parse(envelope)
       assert msg.from_email == "alice@example.com"

From a6a6086d6ac5b4d1f27938e00ae65e3c6269071e Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Fri, 24 Apr 2026 08:22:02 -0400
Subject: [PATCH 06/22] test(inbound): parser equivalence across Postmark /
 Mailgun / SES
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Ports escalated-go#37 + escalated-dotnet#31 + escalated-spring#34
to Phoenix/Elixir. Cements the three-provider parser contract:
the same logical email, expressed in each provider's native webhook
payload shape, should normalize to the same Message metadata.

Two ExUnit cases:
  - threading metadata matches (from_email / to_email / subject /
    in_reply_to / references) across all three parsers.
  - body_text matches — Postmark + Mailgun forward directly, SES
    needs the base64 MIME dance.

Shared @sample + *_payload/1 builders mean adding a fourth provider
validates against the existing three for free.
---
 .../email/inbound/parser_equivalence_test.exs | 130 ++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 test/escalated/services/email/inbound/parser_equivalence_test.exs

diff --git a/test/escalated/services/email/inbound/parser_equivalence_test.exs b/test/escalated/services/email/inbound/parser_equivalence_test.exs
new file mode 100644
index 0000000..8885034
--- /dev/null
+++ b/test/escalated/services/email/inbound/parser_equivalence_test.exs
@@ -0,0 +1,130 @@
+defmodule Escalated.Services.Email.Inbound.ParserEquivalenceTest do
+  @moduledoc """
+  Parser-equivalence tests: the same logical email, expressed in each
+  provider's native webhook payload shape, should normalize to the
+  same `Escalated.Services.Email.Inbound.Message` metadata. Parser
+  equivalence at this layer guarantees a reply delivered via any
+  provider routes to the same ticket via the same threading chain.
+
+  Mirrors escalated-go#37 + escalated-dotnet#31 + escalated-spring#34.
+  Adding a fourth provider in the future can reuse the same
+  `logical_email/0` + `*_payload/1` builders and get contract
+  validation for free.
+  """
+
+  use ExUnit.Case, async: true
+
+  alias Escalated.Services.Email.Inbound.{
+    MailgunParser,
+    PostmarkParser,
+    SESParser
+  }
+
+  @sample %{
+    from_email: "alice@example.com",
+    from_name: "Alice",
+    to_email: "support@example.com",
+    subject: "Re: Help with invoice",
+    body_text: "Thanks for the quick response.",
+    message_id: "<external-reply-xyz@mail.alice.com>",
+    in_reply_to: "<ticket-42@support.example.com>",
+    references: "<ticket-42@support.example.com>"
+  }
+
+  defp postmark_payload(e) do
+    %{
+      "FromFull" => %{"Email" => e.from_email, "Name" => e.from_name},
+      "To" => e.to_email,
+      "Subject" => e.subject,
+      "TextBody" => e.body_text,
+      "Headers" => [
+        %{"Name" => "Message-ID", "Value" => e.message_id},
+        %{"Name" => "In-Reply-To", "Value" => e.in_reply_to},
+        %{"Name" => "References", "Value" => e.references}
+      ]
+    }
+  end
+
+  defp mailgun_payload(e) do
+    %{
+      "sender" => e.from_email,
+      "from" => "#{e.from_name} <#{e.from_email}>",
+      "recipient" => e.to_email,
+      "subject" => e.subject,
+      "body-plain" => e.body_text,
+      "Message-Id" => e.message_id,
+      "In-Reply-To" => e.in_reply_to,
+      "References" => e.references
+    }
+  end
+
+  defp ses_payload(e) do
+    # Include full raw MIME as base64 so body extraction is exercised
+    # — keeps the payload close to a real SES delivery.
+    mime =
+      "From: #{e.from_name} <#{e.from_email}>\r\n" <>
+        "To: #{e.to_email}\r\n" <>
+        "Subject: #{e.subject}\r\n" <>
+        "Message-ID: #{e.message_id}\r\n" <>
+        "In-Reply-To: #{e.in_reply_to}\r\n" <>
+        "References: #{e.references}\r\n" <>
+        "Content-Type: text/plain; charset=\"utf-8\"\r\n" <>
+        "\r\n" <>
+        e.body_text
+
+    ses_message = %{
+      "notificationType" => "Received",
+      "mail" => %{
+        "source" => e.from_email,
+        "destination" => [e.to_email],
+        "headers" => [
+          %{"name" => "From", "value" => "#{e.from_name} <#{e.from_email}>"},
+          %{"name" => "To", "value" => e.to_email},
+          %{"name" => "Subject", "value" => e.subject},
+          %{"name" => "Message-ID", "value" => e.message_id},
+          %{"name" => "In-Reply-To", "value" => e.in_reply_to},
+          %{"name" => "References", "value" => e.references}
+        ],
+        "commonHeaders" => %{
+          "from" => ["#{e.from_name} <#{e.from_email}>"],
+          "to" => [e.to_email],
+          "subject" => e.subject
+        }
+      },
+      "content" => Base.encode64(mime)
+    }
+
+    %{
+      "Type" => "Notification",
+      "Message" => Jason.encode!(ses_message)
+    }
+  end
+
+  describe "normalizes to same message" do
+    test "threading metadata matches across Postmark / Mailgun / SES" do
+      {:ok, postmark} = PostmarkParser.parse(postmark_payload(@sample))
+      {:ok, mailgun} = MailgunParser.parse(mailgun_payload(@sample))
+      {:ok, ses} = SESParser.parse(ses_payload(@sample))
+
+      for {name, msg} <- [{"postmark", postmark}, {"mailgun", mailgun}, {"ses", ses}] do
+        assert msg.from_email == @sample.from_email, "#{name}: from_email mismatch"
+        assert msg.to_email == @sample.to_email, "#{name}: to_email mismatch"
+        assert msg.subject == @sample.subject, "#{name}: subject mismatch"
+        assert msg.in_reply_to == @sample.in_reply_to, "#{name}: in_reply_to mismatch"
+        assert msg.references == @sample.references, "#{name}: references mismatch"
+      end
+    end
+  end
+
+  describe "body extraction matches" do
+    test "body_text matches across all three parsers" do
+      {:ok, postmark} = PostmarkParser.parse(postmark_payload(@sample))
+      {:ok, mailgun} = MailgunParser.parse(mailgun_payload(@sample))
+      {:ok, ses} = SESParser.parse(ses_payload(@sample))
+
+      assert postmark.body_text == @sample.body_text
+      assert mailgun.body_text == @sample.body_text
+      assert ses.body_text == @sample.body_text
+    end
+  end
+end

From 8863e38e0c998747f6cd30189baf851f01ee97f8 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 22:45:47 -0400
Subject: [PATCH 07/22] style(phoenix): wrap long line for mix format

---
 lib/escalated/services/email/inbound/postmark_parser.ex | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/escalated/services/email/inbound/postmark_parser.ex b/lib/escalated/services/email/inbound/postmark_parser.ex
index c2c7de3..1187fe0 100644
--- a/lib/escalated/services/email/inbound/postmark_parser.ex
+++ b/lib/escalated/services/email/inbound/postmark_parser.ex
@@ -50,8 +50,7 @@ defmodule Escalated.Services.Email.Inbound.PostmarkParser do
        subject: Map.get(payload, "Subject") || "",
        body_text: blank_to_nil(Map.get(payload, "TextBody")),
        body_html: blank_to_nil(Map.get(payload, "HtmlBody")),
-       message_id:
-         first_nonempty(Map.get(payload, "MessageID"), Map.get(headers, "Message-ID")),
+       message_id: first_nonempty(Map.get(payload, "MessageID"), Map.get(headers, "Message-ID")),
        in_reply_to: Map.get(headers, "In-Reply-To"),
        references: Map.get(headers, "References"),
        headers: headers,

From 060a589821d5bae1c7c89b1e2aa99ff52f39e44c Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 22:49:12 -0400
Subject: [PATCH 08/22] style(phoenix): wrap long lines for mix format

---
 test/escalated/services/email/inbound/router_test.exs  | 4 +++-
 test/escalated/services/email/inbound/service_test.exs | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/test/escalated/services/email/inbound/router_test.exs b/test/escalated/services/email/inbound/router_test.exs
index 554d410..2747fd5 100644
--- a/test/escalated/services/email/inbound/router_test.exs
+++ b/test/escalated/services/email/inbound/router_test.exs
@@ -54,7 +54,9 @@ defmodule Escalated.Services.Email.Inbound.RouterTest do
       to = MessageIdUtil.build_reply_to(42, @secret, @domain)
       m = message(to_email: to)
 
-      result = Router.resolve_ticket(m, lookup(by_id: %{42 => ticket}), %{inbound_secret: @secret})
+      result =
+        Router.resolve_ticket(m, lookup(by_id: %{42 => ticket}), %{inbound_secret: })
+
       assert result == ticket
     end
 
diff --git a/test/escalated/services/email/inbound/service_test.exs b/test/escalated/services/email/inbound/service_test.exs
index ea3f1c2..7e4cdbf 100644
--- a/test/escalated/services/email/inbound/service_test.exs
+++ b/test/escalated/services/email/inbound/service_test.exs
@@ -108,7 +108,9 @@ defmodule Escalated.Services.Email.Inbound.ServiceTest do
 
     test "SNS confirmation → skipped" do
       w = writer()
-      m = message(%{from_email: "no-reply@sns.amazonaws.com", subject: "SubscriptionConfirmation"})
+
+      m =
+        message(%{from_email: "no-reply@sns.amazonaws.com", subject: "SubscriptionConfirmation"})
 
       assert {:ok, result} = Service.process(m, lookup(), w)
       assert result.outcome == :skipped

From 3585acf46b759ac47a4524a4865c58ed17d51275 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 22:49:42 -0400
Subject: [PATCH 09/22] style(phoenix): alphabetize aliases + extract
 pending_downloads helpers

---
 .../controllers/inbound_email_controller.ex   |  2 +-
 .../services/email/inbound/service.ex         | 30 +++++++++++--------
 2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/lib/escalated/controllers/inbound_email_controller.ex b/lib/escalated/controllers/inbound_email_controller.ex
index 8be1191..a96c769 100644
--- a/lib/escalated/controllers/inbound_email_controller.ex
+++ b/lib/escalated/controllers/inbound_email_controller.ex
@@ -33,9 +33,9 @@ defmodule Escalated.Controllers.InboundEmailController do
   use Phoenix.Controller, formats: [:json]
   import Plug.Conn
 
+  alias Escalated.Schemas.Ticket
   alias Escalated.Services.Email.Inbound.Service
   alias Escalated.Services.TicketService
-  alias Escalated.Schemas.Ticket
 
   @default_parsers [Escalated.Services.Email.Inbound.PostmarkParser]
 
diff --git a/lib/escalated/services/email/inbound/service.ex b/lib/escalated/services/email/inbound/service.ex
index 89fd13a..2c2a7bc 100644
--- a/lib/escalated/services/email/inbound/service.ex
+++ b/lib/escalated/services/email/inbound/service.ex
@@ -188,19 +188,23 @@ defmodule Escalated.Services.Email.Inbound.Service do
     attachments = Map.get(message, :attachments) || Map.get(message, "attachments") || []
 
     attachments
-    |> Enum.filter(fn a ->
-      url = Map.get(a, :download_url) || Map.get(a, "download_url")
-      content = Map.get(a, :content) || Map.get(a, "content")
-      is_binary(url) and url != "" and (is_nil(content) or content == "")
-    end)
-    |> Enum.map(fn a ->
-      %{
-        name: Map.get(a, :name) || Map.get(a, "name"),
-        content_type: Map.get(a, :content_type) || Map.get(a, "content_type"),
-        size_bytes: Map.get(a, :size_bytes) || Map.get(a, "size_bytes"),
-        download_url: Map.get(a, :download_url) || Map.get(a, "download_url")
-      }
-    end)
+    |> Enum.filter(&provider_hosted?/1)
+    |> Enum.map(&to_pending_download/1)
+  end
+
+  defp provider_hosted?(a) do
+    url = Map.get(a, :download_url) || Map.get(a, "download_url")
+    content = Map.get(a, :content) || Map.get(a, "content")
+    is_binary(url) and url != "" and (is_nil(content) or content == "")
+  end
+
+  defp to_pending_download(a) do
+    %{
+      name: Map.get(a, :name) || Map.get(a, "name"),
+      content_type: Map.get(a, :content_type) || Map.get(a, "content_type"),
+      size_bytes: Map.get(a, :size_bytes) || Map.get(a, "size_bytes"),
+      download_url: Map.get(a, :download_url) || Map.get(a, "download_url")
+    }
   end
 
   defp ticket_id(%{id: id}), do: id

From 6ae662df3f5fedbacef5f12b8d163cf5d5f568cb Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 22:53:19 -0400
Subject: [PATCH 10/22] fix(phoenix): restore @secret reference in router_test

---
 test/escalated/services/email/inbound/router_test.exs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/escalated/services/email/inbound/router_test.exs b/test/escalated/services/email/inbound/router_test.exs
index 2747fd5..2f9717d 100644
--- a/test/escalated/services/email/inbound/router_test.exs
+++ b/test/escalated/services/email/inbound/router_test.exs
@@ -55,7 +55,7 @@ defmodule Escalated.Services.Email.Inbound.RouterTest do
       m = message(to_email: to)
 
       result =
-        Router.resolve_ticket(m, lookup(by_id: %{42 => ticket}), %{inbound_secret: })
+        Router.resolve_ticket(m, lookup(by_id: %{42 => ticket}), %{inbound_secret: @secret})
 
       assert result == ticket
     end

From 2c22844d7187bd96744042ca5bf42c2e8b83315e Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 22:58:06 -0400
Subject: [PATCH 11/22] style(phoenix): sync router.ex to master

---
 .../services/email/inbound/router.ex          | 26 +++++++++----------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/lib/escalated/services/email/inbound/router.ex b/lib/escalated/services/email/inbound/router.ex
index 536706b..452f157 100644
--- a/lib/escalated/services/email/inbound/router.ex
+++ b/lib/escalated/services/email/inbound/router.ex
@@ -55,20 +55,18 @@ defmodule Escalated.Services.Email.Inbound.Router do
     # 1 + 2. Parse canonical Message-IDs out of our own headers.
     ticket = resolve_by_header_message_ids(message, lookup)
 
-    cond do
-      not is_nil(ticket) ->
-        ticket
-
-      true ->
-        # 3. Signed Reply-To on the recipient address.
-        case resolve_by_signed_reply_to(message, lookup, options) do
-          nil ->
-            # 4. Subject-line reference tag.
-            resolve_by_subject_reference(message, lookup, options)
-
-          signed_ticket ->
-            signed_ticket
-        end
+    if is_nil(ticket) do
+      # 3. Signed Reply-To on the recipient address.
+      case resolve_by_signed_reply_to(message, lookup, options) do
+        nil ->
+          # 4. Subject-line reference tag.
+          resolve_by_subject_reference(message, lookup, options)
+
+        signed_ticket ->
+          signed_ticket
+      end
+    else
+      ticket
     end
   end
 

From 777fc301dda0c94311cc1ecd9fb0a121b2bea2d8 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 23:02:57 -0400
Subject: [PATCH 12/22] style(phoenix): wrap long lines for mix format

---
 .../services/email/inbound/attachment_downloader.ex      | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/lib/escalated/services/email/inbound/attachment_downloader.ex b/lib/escalated/services/email/inbound/attachment_downloader.ex
index f9f83ec..814184d 100644
--- a/lib/escalated/services/email/inbound/attachment_downloader.ex
+++ b/lib/escalated/services/email/inbound/attachment_downloader.ex
@@ -50,8 +50,9 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloader do
   @type pending :: Service.pending_attachment()
 
   @type storage :: %{
-          required(:put) => (String.t(), binary(), String.t() ->
-                               {:ok, String.t()} | {:error, any()})
+          required(:put) =>
+            (String.t(), binary(), String.t() ->
+               {:ok, String.t()} | {:error, any()})
         }
 
   @type writer :: %{
@@ -177,7 +178,9 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloader do
     _ = :application.ensure_all_started(:ssl)
 
     charlist_url = String.to_charlist(url)
-    charlist_headers = Enum.map(headers, fn {k, v} -> {String.to_charlist(k), String.to_charlist(v)} end)
+
+    charlist_headers =
+      Enum.map(headers, fn {k, v} -> {String.to_charlist(k), String.to_charlist(v)} end)
 
     case :httpc.request(:get, {charlist_url, charlist_headers}, [], body_format: :binary) do
       {:ok, {{_version, status, _reason}, resp_headers, body}} ->

From 8404eeea94b2a40b8af3bc911f9d5fcb76198fa3 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 23:03:17 -0400
Subject: [PATCH 13/22] style(phoenix): wrap long line in local_file_storage
 for mix format

---
 lib/escalated/services/email/inbound/local_file_storage.ex | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/escalated/services/email/inbound/local_file_storage.ex b/lib/escalated/services/email/inbound/local_file_storage.ex
index b5e5948..15b04ea 100644
--- a/lib/escalated/services/email/inbound/local_file_storage.ex
+++ b/lib/escalated/services/email/inbound/local_file_storage.ex
@@ -22,7 +22,10 @@ defmodule Escalated.Services.Email.Inbound.LocalFileStorage do
     %{
       put: fn filename, content, _content_type ->
         now = DateTime.utc_now()
-        prefix = DateTime.to_iso8601(now, :basic) <> "-" <> Integer.to_string(now.microsecond |> elem(0))
+
+        prefix =
+          DateTime.to_iso8601(now, :basic) <> "-" <> Integer.to_string(now.microsecond |> elem(0))
+
         stored_name = "#{prefix}-#{filename}"
         full_path = Path.join(root, stored_name)
 

From 1e771e2f8a1254e12b45a4a1e932e941f8da2f9b Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 23:05:54 -0400
Subject: [PATCH 14/22] style(phoenix): wrap content-type stub for mix format

---
 .../services/email/inbound/attachment_downloader_test.exs     | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/test/escalated/services/email/inbound/attachment_downloader_test.exs b/test/escalated/services/email/inbound/attachment_downloader_test.exs
index cf127a1..c2e404e 100644
--- a/test/escalated/services/email/inbound/attachment_downloader_test.exs
+++ b/test/escalated/services/email/inbound/attachment_downloader_test.exs
@@ -174,7 +174,9 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloaderTest do
     end
 
     test "falls back to response Content-Type when pending content_type is blank" do
-      stub_response({:ok, %{status: 200, body: <<1, 2, 3>>, headers: [{"Content-Type", "image/png"}]}})
+      stub_response(
+        {:ok, %{status: 200, body: <<1, 2, 3>>, headers: [{"Content-Type", "image/png"}]}}
+      )
       storage = fake_storage()
       writer = fake_writer()
 

From f8cf517b9e40f416df9ba38de2f1acd78a4e58e1 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 23:06:13 -0400
Subject: [PATCH 15/22] style(phoenix): wrap hello-pdf stub for mix format

---
 .../services/email/inbound/attachment_downloader_test.exs     | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/test/escalated/services/email/inbound/attachment_downloader_test.exs b/test/escalated/services/email/inbound/attachment_downloader_test.exs
index c2e404e..0d54be1 100644
--- a/test/escalated/services/email/inbound/attachment_downloader_test.exs
+++ b/test/escalated/services/email/inbound/attachment_downloader_test.exs
@@ -78,7 +78,9 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloaderTest do
 
   describe "download/6" do
     test "happy path persists attachment" do
-      stub_response({:ok, %{status: 200, body: "hello pdf", headers: [{"Content-Type", "application/pdf"}]}})
+      stub_response(
+        {:ok, %{status: 200, body: "hello pdf", headers: [{"Content-Type", "application/pdf"}]}}
+      )
       storage = fake_storage(path: "/store/report.pdf")
       writer = fake_writer(attachment: %{id: 1, original_filename: "report.pdf"})
 

From c3c07fae2f01e966addd3bac5d512de057679edd Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 23:08:26 -0400
Subject: [PATCH 16/22] style(phoenix): wrap reply_id assertion line for mix
 format

---
 .../services/email/inbound/attachment_downloader_test.exs      | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/test/escalated/services/email/inbound/attachment_downloader_test.exs b/test/escalated/services/email/inbound/attachment_downloader_test.exs
index 0d54be1..7192ec5 100644
--- a/test/escalated/services/email/inbound/attachment_downloader_test.exs
+++ b/test/escalated/services/email/inbound/attachment_downloader_test.exs
@@ -107,7 +107,8 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloaderTest do
       storage = fake_storage()
       writer = fake_writer()
 
-      assert {:ok, _} = AttachmentDownloader.download(pending(), 42, 7, storage, writer, options())
+      assert {:ok, _} =
+               AttachmentDownloader.download(pending(), 42, 7, storage, writer, options())
 
       [{:create, attrs}] = :ets.tab2list(writer._ets)
       assert attrs.reply_id == 7

From c6a955614cdbf08836addaf31a781a0fb270be77 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 23:16:30 -0400
Subject: [PATCH 17/22] style(phoenix): replace single-condition cond with if

---
 .../services/email/inbound/attachment_downloader.ex    | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/lib/escalated/services/email/inbound/attachment_downloader.ex b/lib/escalated/services/email/inbound/attachment_downloader.ex
index 814184d..ede4783 100644
--- a/lib/escalated/services/email/inbound/attachment_downloader.ex
+++ b/lib/escalated/services/email/inbound/attachment_downloader.ex
@@ -81,12 +81,10 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloader do
       when is_map(pending) do
     url = Map.get(pending, :download_url) || Map.get(pending, "download_url")
 
-    cond do
-      is_nil(url) or url == "" ->
-        {:error, :missing_download_url}
-
-      true ->
-        do_download(pending, url, ticket_id, reply_id, storage, writer, options)
+    if is_nil(url) or url == "" do
+      {:error, :missing_download_url}
+    else
+      do_download(pending, url, ticket_id, reply_id, storage, writer, options)
     end
   end
 

From 4d164c50f7933b61cc2a178045f428ff8c420511 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 23:19:18 -0400
Subject: [PATCH 18/22] style(phoenix): wrap long lines in ses_parser +
 downloader tests

---
 .../services/email/inbound/ses_parser.ex        | 17 +++++++++++------
 .../inbound/attachment_downloader_test.exs      |  2 +-
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/lib/escalated/services/email/inbound/ses_parser.ex b/lib/escalated/services/email/inbound/ses_parser.ex
index 72921b1..a8da443 100644
--- a/lib/escalated/services/email/inbound/ses_parser.ex
+++ b/lib/escalated/services/email/inbound/ses_parser.ex
@@ -264,12 +264,17 @@ defmodule Escalated.Services.Email.Inbound.SESParser do
 
   defp decode_body(body, transfer_enc) do
     case String.downcase(String.trim(transfer_enc)) do
-      "quoted-printable" -> decode_quoted_printable(body)
-      "base64" -> case Base.decode64(body, ignore: :whitespace) do
-        {:ok, decoded} -> decoded
-        :error -> body
-      end
-      _ -> body
+      "quoted-printable" ->
+        decode_quoted_printable(body)
+
+      "base64" ->
+        case Base.decode64(body, ignore: :whitespace) do
+          {:ok, decoded} -> decoded
+          :error -> body
+        end
+
+      _ ->
+        body
     end
   end
 
diff --git a/test/escalated/services/email/inbound/attachment_downloader_test.exs b/test/escalated/services/email/inbound/attachment_downloader_test.exs
index 7192ec5..fe8b17d 100644
--- a/test/escalated/services/email/inbound/attachment_downloader_test.exs
+++ b/test/escalated/services/email/inbound/attachment_downloader_test.exs
@@ -24,7 +24,7 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloaderTest do
     """
     def get(:get, _url, _headers) do
       [status | rest] = Process.get(:__ad_sequence__, [200])
-      Process.put(:__ad_sequence__, rest == [] and [200] or rest)
+      Process.put(:__ad_sequence__, (rest == [] and [200]) or rest)
       {:ok, %{status: status, body: "ok", headers: []}}
     end
   end

From 3aa58474875654059006dc2f6de22758bce963f0 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 23:26:42 -0400
Subject: [PATCH 19/22] style(phoenix): blank-line wrap for stub_response calls

---
 .../services/email/inbound/attachment_downloader_test.exs       | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/test/escalated/services/email/inbound/attachment_downloader_test.exs b/test/escalated/services/email/inbound/attachment_downloader_test.exs
index fe8b17d..2856c30 100644
--- a/test/escalated/services/email/inbound/attachment_downloader_test.exs
+++ b/test/escalated/services/email/inbound/attachment_downloader_test.exs
@@ -81,6 +81,7 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloaderTest do
       stub_response(
         {:ok, %{status: 200, body: "hello pdf", headers: [{"Content-Type", "application/pdf"}]}}
       )
+
       storage = fake_storage(path: "/store/report.pdf")
       writer = fake_writer(attachment: %{id: 1, original_filename: "report.pdf"})
 
@@ -180,6 +181,7 @@ defmodule Escalated.Services.Email.Inbound.AttachmentDownloaderTest do
       stub_response(
         {:ok, %{status: 200, body: <<1, 2, 3>>, headers: [{"Content-Type", "image/png"}]}}
       )
+
       storage = fake_storage()
       writer = fake_writer()
 

From 947d4f7779bbe3895f8d2ca3a5f9114bec60222b Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 23:27:04 -0400
Subject: [PATCH 20/22] style(phoenix): wrap nested map literals in
 ses_parser_test for mix format

---
 .../email/inbound/ses_parser_test.exs         | 41 ++++++++++---------
 1 file changed, 22 insertions(+), 19 deletions(-)

diff --git a/test/escalated/services/email/inbound/ses_parser_test.exs b/test/escalated/services/email/inbound/ses_parser_test.exs
index 2957143..524a9c1 100644
--- a/test/escalated/services/email/inbound/ses_parser_test.exs
+++ b/test/escalated/services/email/inbound/ses_parser_test.exs
@@ -28,26 +28,29 @@ defmodule Escalated.Services.Email.Inbound.SESParserTest do
 
   describe "notification" do
     test "extracts full threading metadata from commonHeaders + headers" do
-      envelope = notification_envelope(%{
-        "mail" => %{
-          "source" => "alice@example.com",
-          "destination" => ["support@example.com"],
-          "headers" => [
-            %{"name" => "From", "value" => "Alice <alice@example.com>"},
-            %{"name" => "To", "value" => "support@example.com"},
-            %{"name" => "Subject", "value" => "[ESC-42] Re: Help"},
-            %{"name" => "Message-ID", "value" => "<external-xyz@mail.alice.com>"},
-            %{"name" => "In-Reply-To", "value" => "<ticket-42@support.example.com>"},
-            %{"name" => "References",
-              "value" => "<ticket-42@support.example.com> <prev@mail.com>"}
-          ],
-          "commonHeaders" => %{
-            "from" => ["Alice <alice@example.com>"],
-            "to" => ["support@example.com"],
-            "subject" => "[ESC-42] Re: Help"
+      envelope =
+        notification_envelope(%{
+          "mail" => %{
+            "source" => "alice@example.com",
+            "destination" => ["support@example.com"],
+            "headers" => [
+              %{"name" => "From", "value" => "Alice <alice@example.com>"},
+              %{"name" => "To", "value" => "support@example.com"},
+              %{"name" => "Subject", "value" => "[ESC-42] Re: Help"},
+              %{"name" => "Message-ID", "value" => "<external-xyz@mail.alice.com>"},
+              %{"name" => "In-Reply-To", "value" => "<ticket-42@support.example.com>"},
+              %{
+                "name" => "References",
+                "value" => "<ticket-42@support.example.com> <prev@mail.com>"
+              }
+            ],
+            "commonHeaders" => %{
+              "from" => ["Alice <alice@example.com>"],
+              "to" => ["support@example.com"],
+              "subject" => "[ESC-42] Re: Help"
+            }
           }
-        }
-      })
+        })
 
       assert {:ok, msg} = SESParser.parse(envelope)
       assert msg.from_email == "alice@example.com"

From 8f30197d38f71389b68e3b4e34ebd086b81a20a2 Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 23:30:56 -0400
Subject: [PATCH 21/22] refactor(phoenix): extract walk_multipart helpers to
 satisfy Credo

---
 .../services/email/inbound/ses_parser.ex      | 45 +++++++++----------
 1 file changed, 21 insertions(+), 24 deletions(-)

diff --git a/lib/escalated/services/email/inbound/ses_parser.ex b/lib/escalated/services/email/inbound/ses_parser.ex
index a8da443..46c2339 100644
--- a/lib/escalated/services/email/inbound/ses_parser.ex
+++ b/lib/escalated/services/email/inbound/ses_parser.ex
@@ -211,34 +211,31 @@ defmodule Escalated.Services.Email.Inbound.SESParser do
 
   defp walk_multipart(body, content_type) do
     case extract_boundary(content_type) do
-      nil ->
-        {nil, nil}
-
-      boundary ->
-        parts = split_multipart(body, boundary)
-
-        Enum.reduce(parts, {nil, nil}, fn part, {text, html} ->
-          case split_headers(part) do
-            {:ok, part_headers, part_body} ->
-              part_type = Map.get(part_headers, "content-type", "")
-              part_enc = Map.get(part_headers, "content-transfer-encoding", "7bit")
-              decoded = decode_body(String.trim(part_body), part_enc)
+      nil -> {nil, nil}
+      boundary -> Enum.reduce(split_multipart(body, boundary), {nil, nil}, &fold_part/2)
+    end
+  end
 
-              cond do
-                String.starts_with?(String.downcase(part_type), "text/plain") and is_nil(text) ->
-                  {decoded, html}
+  defp fold_part(part, {text, html}) do
+    case split_headers(part) do
+      {:ok, part_headers, part_body} ->
+        part_type = Map.get(part_headers, "content-type", "")
+        part_enc = Map.get(part_headers, "content-transfer-encoding", "7bit")
+        decoded = decode_body(String.trim(part_body), part_enc)
+        merge_part(text, html, part_type, decoded)
 
-                String.starts_with?(String.downcase(part_type), "text/html") and is_nil(html) ->
-                  {text, decoded}
+      _ ->
+        {text, html}
+    end
+  end
 
-                true ->
-                  {text, html}
-              end
+  defp merge_part(text, html, part_type, decoded) do
+    type = String.downcase(part_type)
 
-            _ ->
-              {text, html}
-          end
-        end)
+    cond do
+      String.starts_with?(type, "text/plain") and is_nil(text) -> {decoded, html}
+      String.starts_with?(type, "text/html") and is_nil(html) -> {text, decoded}
+      true -> {text, html}
     end
   end
 

From 3646be7d5fa2bd7c6c3a90215245a6eb6ba7a35d Mon Sep 17 00:00:00 2001
From: Matt Gros <3311227+mpge@users.noreply.github.com>
Date: Sun, 26 Apr 2026 23:43:42 -0400
Subject: [PATCH 22/22] refactor(phoenix): unwind pipe-into-anonymous in
 decode_quoted_printable

---
 lib/escalated/services/email/inbound/ses_parser.ex | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/lib/escalated/services/email/inbound/ses_parser.ex b/lib/escalated/services/email/inbound/ses_parser.ex
index 46c2339..121b690 100644
--- a/lib/escalated/services/email/inbound/ses_parser.ex
+++ b/lib/escalated/services/email/inbound/ses_parser.ex
@@ -276,13 +276,11 @@ defmodule Escalated.Services.Email.Inbound.SESParser do
   end
 
   defp decode_quoted_printable(body) do
-    body
-    |> String.replace(~r/=\r?\n/, "")
-    |> (fn stripped ->
-          Regex.replace(~r/=([0-9A-Fa-f]{2})/, stripped, fn _match, hex ->
-            <<String.to_integer(hex, 16)>>
-          end)
-        end).()
+    stripped = String.replace(body, ~r/=\r?\n/, "")
+
+    Regex.replace(~r/=([0-9A-Fa-f]{2})/, stripped, fn _match, hex ->
+      <<String.to_integer(hex, 16)>>
+    end)
   end
 
   defp blank_to_nil(nil), do: nil