diff --git a/contrib/immich.lua b/contrib/immich.lua
new file mode 100644
index 00000000..89162719
--- /dev/null
+++ b/contrib/immich.lua
@@ -0,0 +1,995 @@
+--[[
+  This file is part of darktable,
+  copyright (c) 2024 Giorgio Massussi
+  copyright (c) 2026 Colin Holzman
+
+  darktable is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  darktable is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with darktable.  If not, see <http://www.gnu.org/licenses/>.
+]]
+--[[
+IMMICH
+Upload selection to an Immich server
+
+USAGE
+This plugin allows you to upload selected photos to an Immich server (https://immich.app/)
+Each image is tracked with darktable tags so re-exporting is safe and cheap:
+* an "immich|asset|<id>" tag remembers the uploaded asset id for that image
+* an "immich|change|<timestamp>" tag remembers the darktable change timestamp at export time
+If an image's change timestamp still matches the cached tag and "Skip unchanged" is
+enabled, the export is skipped locally without contacting the Immich server at all.
+Otherwise the plugin looks up the cached asset on the server; if it no longer exists
+there, or has been trashed, it is treated as gone and the image is uploaded fresh.
+When the cached asset is still present, the "Re-export Behavior" option controls what
+happens to it: delete/trash it, stack the new upload with it, both, or leave it alone
+and upload the image as a new, separate asset.
+
+Album assignment is controlled by the "Album mode" option:
+* No album: exported assets are not added to any album
+* Custom / Copy existing + Custom: assets are added to the album named in the "Album Title" field
+* Copy albums from existing asset: assets are added to whatever albums the previous
+  version of the asset already belonged to on the server
+* Use Album Title: same as Custom, using the "Album Title" field as the album name
+The "Album Title" field is prefilled with the folder name of the exported image when
+a title-based mode is selected, but can be edited freely.
+
+In the lua options you must specify:
+* the hostname of the server immich
+* an api key generated in the Account settings - API Keys menu of the immich server
+The lua options also let you set the defaults for "Album mode", "Skip unchanged", and
+"Re-export Behavior" shown above, so the export panel opens with your preferred choices.
+An "Immich debug logging" option is also available there to log every request/response
+to the darktable debug log, which is useful when troubleshooting a failed upload.
+
+API KEY PERMISSIONS
+When creating the API key on the Immich server, grant it these permissions:
+* asset.read       - look up a previously uploaded asset's status
+* asset.upload     - upload exported images
+* asset.update     - required by the server when stacking a new upload with an existing asset
+* asset.delete     - delete/trash the previous asset when "Re-export Behavior" removes it
+* album.read       - find existing albums by name, and look up an asset's albums
+* album.create     - create the album when it doesn't already exist
+* albumAsset.create - add uploaded assets to an album
+* stack.create     - stack a new upload with an existing asset
+
+INSTALL
+* install luasec, cjson, and luasocket for darktable's Lua version (currently 5.4) on your system
+* if darktable can't find them (common on macOS/Windows, where it bundles its own
+  Lua), set the "immich: Lua module install prefix" preference in the lua options
+  to the folder containing share/lua/<ver> and lib/lua/<ver>, then restart
+
+]]
+local dt = require "darktable"
+local du = require "lib/dtutils"
+local df = require "lib/dtutils.file"
+local log = require "lib/dtutils.log"
+
+local gettext = dt.gettext.gettext
+
+local function _(msgid)
+    return gettext(msgid)
+end
+
+-- forward declaration so store_image() (defined above its widget) resolves this
+-- as an upvalue rather than a nil global
+local title_widget
+local album_mode_widget
+local album_title_row_widget
+local existing_asset_action_widget
+local skip_unchanged_widget
+local prefill_title_widget_from_images
+
+local ALBUM_MODE_NONE = 1
+local ALBUM_MODE_TITLE = 2
+local ALBUM_MODE_COPY_EXISTING = 3
+local ALBUM_MODE_COPY_AND_TITLE = 4
+local ALBUM_MODE_USE_ALBUM_TITLE = 5
+
+local EXISTING_ASSET_ACTION_DELETE = 1
+local EXISTING_ASSET_ACTION_STACK = 2
+local EXISTING_ASSET_ACTION_DELETE_AND_STACK = 3
+local EXISTING_ASSET_ACTION_UPLOAD_NEW = 4
+
+-- Shared between the combobox widgets and the "default value" preferences below,
+-- so the option order only needs to be maintained in one place.
+local ALBUM_MODE_LABELS = {
+  _("No album"),
+  _("Custom"),
+  _("Copy albums from existing asset"),
+  _("Copy existing + Custom"),
+  _("Use Album Title"),
+}
+local EXISTING_ASSET_ACTION_LABELS = {
+  _("Delete/Trash existing asset on server"),
+  _("Stack with existing asset"),
+  _("Delete/Trash & Stack"),
+  _("Upload as new image"),
+}
+
+local function index_of_label(labels, label)
+  for i,candidate in ipairs(labels) do
+    if candidate == label then
+      return i
+    end
+  end
+  return nil
+end
+
+-- Immich requires a deviceId on every uploaded asset, but we no longer use it to
+-- look up previously uploaded assets -- that's handled entirely by the local
+-- "immich|asset|..." / "immich|change|..." darktable tags -- so a fixed value is fine.
+local IMMICH_DEVICE_ID = "darktable"
+
+-- The version (e.g. "5.4") of the Lua interpreter darktable is running -- bundled
+-- on macOS/Windows, the system Lua on Linux. Derived from _VERSION rather than
+-- hardcoded, so the search paths and user-facing messages keep working if
+-- darktable's Lua changes.
+local lua_version = _VERSION:match("(%d+%.%d+)") or "5.4"
+local DEFAULT_LOG_LEVEL <const> = log.warn
+
+local function set_log_level(level)
+  local old_log_level = log.log_level()
+  log.log_level(level)
+  return old_log_level
+end
+
+local function restore_log_level(level)
+  log.log_level(level)
+end
+
+local function image_can_skip_remote_work(image, skip_unchanged)
+  if not skip_unchanged then
+    return false
+  end
+
+  local cached_asset_id = nil
+  local cached_change_marker = nil
+  local tags = image:get_tags()
+  if tags == nil then
+    return false
+  end
+
+  for _,tag in ipairs(tags) do
+    if tag ~= nil and tag.name ~= nil then
+      if cached_asset_id == nil then
+        cached_asset_id = tag.name:match("^immich%|asset%|(.-)$")
+      end
+      if cached_change_marker == nil then
+        cached_change_marker = tag.name:match("^immich%|change%|(.-)$")
+      end
+      if cached_asset_id ~= nil and cached_change_marker ~= nil then
+        break
+      end
+    end
+  end
+
+  if cached_asset_id == nil or cached_change_marker == nil then
+    return false
+  end
+
+  return cached_change_marker == tostring(image.change_timestamp or "")
+end
+
+dt.preferences.register("immich", "immich_debug_logging", "bool",
+  _("Immich debug logging"),
+  _("Enable verbose debug messages for Immich uploads and album updates."),
+  false)
+
+log.log_level(DEFAULT_LOG_LEVEL)
+
+
+
+-- Load optional deps defensively so a missing one yields an actionable message.
+local missing = {}
+local function need(modname, rock)
+  local ok, mod = pcall(require, modname)
+  if not ok then missing[#missing + 1] = string.format("'%s' (%s)", modname, rock) end
+  return ok and mod or nil
+end
+
+local cjson = need("cjson.safe",  "lua-cjson")
+local https = need("ssl.https",   "luasec")
+local http  = need("socket.http", "luasocket")
+local ltn12 = need("ltn12",       "luasocket")
+
+du.check_min_api_version("7.0.0", "immich") 
+
+local function call_immich_api(method,api,body,content_type) 
+  local immichserver = dt.preferences.read("immich","immich_server","string") or ""
+  if immichserver == "" then
+    log.msg(log.debug, "missing Immich server URL (immich_server preference)")
+    return nil, "missing_server_url", nil
+  end
+
+  local client = immichserver:match("^https") and https or http
+  local headers = { }
+  headers["x-api-key"] = dt.preferences.read("immich","immich_key","string") or ""
+  local source = nil
+  if body == nil then
+  elseif (content_type == nil or content_type == "application/json") then
+    headers["Content-Type"] = "application/json"
+    local encoded, enc_err = cjson.encode(body)
+    if not encoded then
+      log.msg(log.debug, "JSON encode failed for /api/" .. tostring(api) .. ": " .. tostring(enc_err))
+      return nil, "json_encode_failed", nil
+    end
+    headers["Content-Length"] = #encoded
+    source = ltn12.source.string(encoded)
+  elseif (content_type == "multipart/form-data") then 
+    local boundary = "----DarktableImmichBoundary" .. math.random(1, 1e16)
+    headers["Content-Type"] = "multipart/form-data; boundary="..boundary
+    source = ltn12.source.empty()
+    local content_length = 0
+    for name,value in pairs(body) do 
+      if (value.filename ~= nil) then 
+        local form_data_table = {}
+        if (content_length > 0) then
+          table.insert(form_data_table,"")
+        end
+        table.insert(form_data_table, "--"..boundary)
+        table.insert(form_data_table, "Content-Disposition: form-data; name=\""..name.."\"; filename=\"".. value.filename .. "\"")
+        table.insert(form_data_table, "Content-Type: application/octet-stream")
+        table.insert(form_data_table, "")
+        table.insert(form_data_table, "")
+        local form_data = table.concat(form_data_table, "\r\n")
+        content_length = content_length+value.file:seek("end")+string.len(form_data)
+        value.file:seek("set",0)
+        source = ltn12.source.simplify(ltn12.source.cat(source,
+          ltn12.source.string(form_data),
+          ltn12.source.file(value.file)))
+      else 
+        local form_data_table = {}
+        if (content_length > 0) then
+          table.insert(form_data_table,"")
+        end
+        table.insert(form_data_table, "--"..boundary)
+        table.insert(form_data_table, "Content-Disposition: form-data; name=\""..name.."\"")
+        table.insert(form_data_table, "")
+        table.insert(form_data_table, value)
+        local form_data = table.concat(form_data_table, "\r\n")
+        content_length = content_length+string.len(form_data)
+        source = ltn12.source.cat(source,ltn12.source.string(form_data))
+      end
+    end
+    content_length = content_length+6+string.len(boundary)
+    source = ltn12.source.cat(source,ltn12.source.string("\r\n--"..boundary.."--"))
+    headers["Content-Length"] = content_length
+  end
+  
+  log.msg(log.debug, "request " .. method .. " /api/" .. api)
+  local res_table={}
+  local res, err, response_headers = client.request{
+    method=method,
+    url=immichserver.."/api/"..api,
+    headers=headers,
+    source=source,
+    sink=ltn12.sink.table(res_table)
+  }
+  local body_text = table.concat(res_table)
+  log.msg(log.debug, "response " .. tostring(err) .. " for /api/" .. api .. " -> " .. body_text)
+  local ct = response_headers ~= nil and response_headers["content-type"] or ""
+  if type(ct) == "string" and string.lower(ct):match("^application/json") then
+    return cjson.decode(body_text), err, response_headers
+  end
+  return body_text, err, response_headers
+end
+
+local function url_encode(str)
+  if str == nil then
+    return ""
+  end
+  return (str:gsub("([^%w%-%_%.%~])", function(c)
+    return string.format("%%%02X", string.byte(c))
+  end))
+end
+
+-- Looks up an album's id by its exact name; album names map to at most one
+-- album, so there's nothing to look up more than once per name.
+local function find_album_id_by_name(album_name)
+  if album_name == nil or album_name == "" then
+    return nil
+  end
+
+  local res_albums, err_albums = call_immich_api("GET", "albums?name=" .. url_encode(album_name))
+  if err_albums ~= 200 or res_albums == nil or res_albums[1] == nil then
+    log.msg(log.debug, "no existing album found named '" .. tostring(album_name) .. "' (HTTP " .. tostring(err_albums) .. ")")
+    return nil
+  end
+
+  return res_albums[1].id
+end
+
+local function initialize(storage,format,images,high_quality,extra_data)
+  local debug_enabled = dt.preferences.read("immich", "immich_debug_logging", "bool")
+  extra_data.log_level = set_log_level(debug_enabled and log.debug or DEFAULT_LOG_LEVEL)
+
+  if #missing > 0 then
+    -- Stash the message for finalize: a dt.print here would be overwritten by
+    -- darktable's own "no image to export" that follows the empty return.
+    extra_data.error = string.format(_("immich: missing Lua libraries (luasocket, luasec, lua-cjson) for Lua %s — install them, set the 'Lua module install prefix' preference if needed, then restart"), lua_version)
+    return {}   -- cancels the export
+  end
+  log.msg(log.debug, "initialize started for " .. tostring(#images) .. " images")
+  extra_data.album_assets = {}
+  extra_data.album_asset_updates = {}
+  extra_data.existing_asset_action = existing_asset_action_widget ~= nil
+      and existing_asset_action_widget.selected or EXISTING_ASSET_ACTION_STACK
+  extra_data.skip_unchanged = skip_unchanged_widget == nil or skip_unchanged_widget.value
+  extra_data.album_mode = album_mode_widget ~= nil and album_mode_widget.selected or ALBUM_MODE_NONE
+  if extra_data.album_mode == ALBUM_MODE_TITLE
+      or extra_data.album_mode == ALBUM_MODE_COPY_AND_TITLE then
+    prefill_title_widget_from_images(images)
+  end
+
+  local all_images_skip_remote = #images > 0
+  for _,image in ipairs(images) do
+    if not image_can_skip_remote_work(image, extra_data.skip_unchanged) then
+      all_images_skip_remote = false
+      break
+    end
+  end
+  if all_images_skip_remote then
+    log.msg(log.debug, "all images matched local cache tags; skipping Immich auth and album lookups")
+    return images
+  end
+
+  -- api-keys/me requires no specific permission (unlike auth/status, which needs "all"),
+  -- so it validates the key and returns its granted permissions in one call.
+  local key_res, key_err = call_immich_api("GET", "api-keys/me")
+  if key_err == 403 then
+    log.msg(log.debug, "authentication failed")
+    extra_data.error = "Authentication error. Check your Immich API key in LUA settings."
+    return {}
+  elseif key_err ~= 200 then
+    log.msg(log.debug, "authentication check returned HTTP " .. tostring(key_err))
+    extra_data.error = "Error contacting Immich server: HTTP " .. key_err
+    return {}
+  end
+
+  local granted_permissions = key_res ~= nil and key_res.permissions or nil
+  local function has_permission(name)
+    if granted_permissions == nil then
+      return true -- couldn't read the permission list; don't block the export on that alone
+    end
+    for _,p in ipairs(granted_permissions) do
+      if p == "all" or p == name then
+        return true
+      end
+    end
+    return false
+  end
+
+  -- Only require what this run's actual settings will use, not the full header list.
+  local required_permissions = {"asset.read", "asset.upload"}
+  if extra_data.existing_asset_action == EXISTING_ASSET_ACTION_DELETE
+      or extra_data.existing_asset_action == EXISTING_ASSET_ACTION_DELETE_AND_STACK then
+    table.insert(required_permissions, "asset.delete")
+  end
+  if extra_data.existing_asset_action == EXISTING_ASSET_ACTION_STACK
+      or extra_data.existing_asset_action == EXISTING_ASSET_ACTION_DELETE_AND_STACK then
+    table.insert(required_permissions, "asset.update")
+    table.insert(required_permissions, "stack.create")
+  end
+  if extra_data.album_mode ~= ALBUM_MODE_NONE then
+    table.insert(required_permissions, "album.read")
+    table.insert(required_permissions, "album.create")
+    table.insert(required_permissions, "albumAsset.create")
+  end
+
+  local missing_permissions = {}
+  for _,permission in ipairs(required_permissions) do
+    if not has_permission(permission) then
+      table.insert(missing_permissions, permission)
+    end
+  end
+
+  if #missing_permissions > 0 then
+    local missing_list = table.concat(missing_permissions, ", ")
+    log.msg(log.debug, "API key is missing required permission(s): " .. missing_list)
+    extra_data.error = "Immich API key is missing required permission(s): " .. missing_list
+        .. ". See the API KEY PERMISSIONS section in this script's header."
+    return {}
+  end
+
+  return images
+end
+
+local function iso_exif_datetime_taken(image) 
+  local exif = image ~= nil and image.exif_datetime_taken or nil
+  if exif == nil or exif == "" then
+    return os.date("!%Y-%m-%dT%H:%M:%S") .. "Z"
+  end
+
+  local yr,mo,dy,h,m,s = string.match(exif, "(%d+):(%d+):(%d+) (%d+):(%d+):(%d+)")
+  if yr == nil then
+    return os.date("!%Y-%m-%dT%H:%M:%S") .. "Z"
+  end
+
+  local timestamp = os.time{year=yr, month=mo, day=dy, hour=h, min=m, sec=s}
+  return os.date("!%Y-%m-%dT%H:%M:%S", timestamp) .. "Z"
+end
+local function get_asset_details(asset_id)
+  if asset_id == nil or asset_id == "" then
+    return nil, nil
+  end
+
+  local res_asset, err_asset = call_immich_api("GET", "assets/" .. tostring(asset_id))
+  if err_asset ~= 200 or res_asset == nil then
+    return nil, err_asset
+  end
+
+  return res_asset, err_asset
+end
+
+local function fetch_asset_album_ids(asset_id)
+  local ids = {}
+  if asset_id == nil or asset_id == "" then
+    return ids
+  end
+
+  local res_albums, err_albums = call_immich_api("GET", "albums?assetId=" .. tostring(asset_id))
+  if err_albums ~= 200 or res_albums == nil then
+    log.msg(log.debug, "failed to look up albums for existing asset " .. tostring(asset_id) .. " with HTTP " .. tostring(err_albums))
+    return ids
+  end
+
+  for _,album in ipairs(res_albums) do
+    if album ~= nil and album.id ~= nil and album.id ~= "" then
+      ids[#ids + 1] = album.id
+    end
+  end
+
+  return ids
+end
+
+local function queue_asset_for_album_id(extra_data, album_id, asset_id)
+  if album_id == nil or album_id == "" or asset_id == nil or asset_id == "" then
+    return
+  end
+
+  local album_assets = extra_data.album_asset_updates[album_id]
+  if album_assets == nil then
+    album_assets = {}
+    extra_data.album_asset_updates[album_id] = album_assets
+  end
+  table.insert(album_assets, asset_id)
+end
+
+local function basename_from_path(path)
+  if path == nil or path == "" then
+    return ""
+  end
+
+  local name = ""
+  for part in string.gmatch(path, "[^/\\]+") do
+    name = part
+  end
+  return name
+end
+
+local function default_album_name_from_images(images)
+  if images == nil or #images == 0 then
+    return ""
+  end
+
+  local first = images[1]
+  if first == nil or first.path == nil then
+    return ""
+  end
+
+  return basename_from_path(first.path)
+end
+
+prefill_title_widget_from_images = function(images)
+  if title_widget == nil then
+    return
+  end
+
+  if title_widget.text ~= nil and title_widget.text ~= "" then
+    return
+  end
+
+  local default_name = default_album_name_from_images(images)
+  if default_name ~= "" then
+    title_widget.text = default_name
+  end
+end
+
+local function prefill_title_widget_from_selection()
+  local ok, action_images = pcall(function()
+    return dt.gui.action_images
+  end)
+  if ok then
+    prefill_title_widget_from_images(action_images)
+  end
+end
+
+local function update_album_title_row_visibility()
+  if album_title_row_widget == nil then
+    return
+  end
+
+  local mode = album_mode_widget ~= nil and album_mode_widget.selected or ALBUM_MODE_NONE
+  album_title_row_widget.visible = (mode == ALBUM_MODE_TITLE
+      or mode == ALBUM_MODE_COPY_AND_TITLE)
+  if album_title_row_widget.visible then
+    prefill_title_widget_from_selection()
+  end
+end
+
+local function upload_image(image,filename) 
+  local date = iso_exif_datetime_taken(image)
+  local f, open_err = io.open(filename, "rb")
+  if f == nil then
+    log.msg(log.debug, "failed to open export file '" .. tostring(filename) .. "': " .. tostring(open_err))
+    return nil
+  end
+  local form_data = {
+    deviceAssetId=tostring(image.id),
+    deviceId=IMMICH_DEVICE_ID,
+    fileCreatedAt=date,
+    fileModifiedAt=date,
+    assetData={
+      filename=df.get_filename(filename),
+      file=f
+    }
+  }
+  log.msg(log.debug, "uploading new asset for image " .. tostring(image.id))
+  local res,err = call_immich_api("POST","assets",form_data,"multipart/form-data")
+  if err == 201 and res ~= nil then
+    log.msg(log.debug, "upload succeeded with asset id " .. tostring(res.id))
+    return res.id
+  end
+  return nil
+end
+
+local function delete_asset(asset_id)
+  if asset_id == nil or asset_id == "" then
+    return false
+  end
+
+  log.msg(log.debug, "deleting previous asset " .. tostring(asset_id))
+  local _delete_res, delete_err = call_immich_api("DELETE", "assets", {ids={asset_id}, force=false})
+  if delete_err == 200 or delete_err == 204 then
+    log.msg(log.debug, "delete succeeded for asset " .. tostring(asset_id))
+    return true
+  end
+
+  log.msg(log.debug, "delete failed for asset " .. tostring(asset_id) .. " with HTTP " .. tostring(delete_err))
+  return false
+end
+
+local function create_stack_with_existing_asset(image,filename,existing_asset_id) 
+  log.msg(log.debug, "uploading new asset for image " .. tostring(image.id) .. " and stacking with existing asset " .. tostring(existing_asset_id))
+  local new_asset_id, upload_err = upload_image(image,filename)
+  if new_asset_id == nil then
+    log.msg(log.debug, "upload failed while preparing stack for image " .. tostring(image.id))
+    return nil
+  end
+
+  local stack_res, stack_err = call_immich_api("POST","stacks",{assetIds={new_asset_id, existing_asset_id}})
+  if stack_err == 201 then
+    log.msg(log.debug, "created stack with primary asset " .. tostring(new_asset_id) .. " and existing asset " .. tostring(existing_asset_id))
+    return new_asset_id
+  end
+
+  log.msg(log.debug, "stack creation failed for image " .. tostring(image.id) .. " with HTTP " .. tostring(stack_err))
+  return new_asset_id
+end
+
+local function get_cached_asset_id(image)
+  local tags = image.get_tags(image)
+  if tags ~= nil then
+    log.msg(log.debug, "checking tags for cached asset id on image " .. tostring(image.id))
+    for _,tag in ipairs(tags) do
+      if tag ~= nil and tag.name ~= nil then
+        local asset_id = tag.name:match("^immich%|asset%|(.-)$")
+        if asset_id ~= nil and asset_id ~= "" then
+          log.msg(log.debug, "found cached asset id " .. tostring(asset_id) .. " in tag " .. tostring(tag.name))
+          return asset_id
+        end
+      end
+    end
+  end
+
+  local id = dt.preferences.read("immich", "asset_" .. tostring(image.id), "string")
+  if id == nil or id == "" then
+    log.msg(log.debug, "no cached asset id found in preferences for image " .. tostring(image.id))
+    return nil
+  end
+  log.msg(log.debug, "found cached asset id " .. tostring(id) .. " in preferences for image " .. tostring(image.id))
+  return id
+end
+
+local function get_cached_change_tag(image)
+  local tags = image.get_tags(image)
+  if tags ~= nil then
+    log.msg(log.debug, "checking tags for cached change marker on image " .. tostring(image.id))
+    for _,tag in ipairs(tags) do
+      if tag ~= nil and tag.name ~= nil then
+        local change_marker = tag.name:match("^immich%|change%|(.-)$")
+        if change_marker ~= nil and change_marker ~= "" then
+          log.msg(log.debug, "found cached change marker " .. tostring(change_marker) .. " in tag " .. tostring(tag.name))
+          return change_marker
+        end
+      end
+    end
+  end
+
+  return nil
+end
+
+local function set_cached_asset_id(image, asset_id)
+  log.msg(log.debug, "writing cached asset id " .. tostring(asset_id) .. " for image " .. tostring(image.id))
+  dt.preferences.write("immich", "asset_" .. tostring(image.id), "string", asset_id)
+
+  local tag_name = "immich|asset|" .. tostring(asset_id)
+  log.msg(log.debug, "ensuring tag " .. tostring(tag_name) .. " exists for image " .. tostring(image.id))
+  local tag = dt.tags.find(tag_name)
+  if tag == nil then
+    tag = dt.tags.create(tag_name)
+  end
+
+  -- Keep only the latest Immich asset tag on the image.
+  local tags = image.get_tags(image)
+  if tags ~= nil then
+    for _,existing_tag in ipairs(tags) do
+      if existing_tag ~= nil and existing_tag.name ~= nil
+          and existing_tag.name:match("^immich%|asset%|") ~= nil
+          and existing_tag.name ~= tag_name then
+        log.msg(log.debug, "detaching old tag " .. tostring(existing_tag.name) .. " from image " .. tostring(image.id))
+        image:detach_tag(existing_tag)
+      end
+    end
+  end
+
+  if tag ~= nil then
+    local already_attached = false
+    if tags ~= nil then
+      for _,existing_tag in ipairs(tags) do
+        if existing_tag ~= nil and existing_tag.name == tag_name then
+          already_attached = true
+          break
+        end
+      end
+    end
+    if not already_attached then
+      log.msg(log.debug, "attaching tag " .. tostring(tag_name) .. " to image " .. tostring(image.id))
+      image:attach_tag(tag)
+    else
+      log.msg(log.debug, "tag " .. tostring(tag_name) .. " already attached to image " .. tostring(image.id))
+    end
+  else
+    log.msg(log.debug, "could not create or find tag " .. tostring(tag_name) .. " for image " .. tostring(image.id))
+  end
+end
+
+local function set_cached_change_tag(image, change_marker)
+  if change_marker == nil or change_marker == "" then
+    log.msg(log.debug, "no change marker available to cache for image " .. tostring(image.id))
+    return
+  end
+
+  local tag_name = "immich|change|" .. tostring(change_marker)
+  log.msg(log.debug, "ensuring change marker tag " .. tostring(tag_name) .. " exists for image " .. tostring(image.id))
+  local tag = dt.tags.find(tag_name)
+  if tag == nil then
+    tag = dt.tags.create(tag_name)
+  end
+
+  local tags = image.get_tags(image)
+  if tags ~= nil then
+    for _,existing_tag in ipairs(tags) do
+      if existing_tag ~= nil and existing_tag.name ~= nil
+          and existing_tag.name:match("^immich%|change%|") ~= nil
+          and existing_tag.name ~= tag_name then
+        log.msg(log.debug, "detaching old change marker tag " .. tostring(existing_tag.name) .. " from image " .. tostring(image.id))
+        image:detach_tag(existing_tag)
+      end
+    end
+  end
+
+  if tag ~= nil then
+    local already_attached = false
+    if tags ~= nil then
+      for _,existing_tag in ipairs(tags) do
+        if existing_tag ~= nil and existing_tag.name == tag_name then
+          already_attached = true
+          break
+        end
+      end
+    end
+    if not already_attached then
+      log.msg(log.debug, "attaching change marker tag " .. tostring(tag_name) .. " to image " .. tostring(image.id))
+      image:attach_tag(tag)
+    else
+      log.msg(log.debug, "change marker tag " .. tostring(tag_name) .. " already attached to image " .. tostring(image.id))
+    end
+  else
+    log.msg(log.debug, "could not create or find change marker tag " .. tostring(tag_name) .. " for image " .. tostring(image.id))
+  end
+end
+
+local function store_image(storage,image,format,filename,number,total,high_quality,extra_data)
+  log.msg(log.debug, "storing image " .. tostring(image.id) .. " (" .. tostring(number) .. "/" .. tostring(total) .. ")")
+  local asset_id = nil
+  local replaced = false
+  local existing_asset_action = extra_data.existing_asset_action or EXISTING_ASSET_ACTION_STACK
+  local skip_unchanged = extra_data.skip_unchanged
+  if skip_unchanged == nil then
+    skip_unchanged = true
+  end
+  local cached_id = get_cached_asset_id(image)
+  local cached_change_marker = get_cached_change_tag(image)
+  local local_change_timestamp = tostring(image.change_timestamp or "")
+  if skip_unchanged and cached_id ~= nil and cached_change_marker ~= nil and cached_change_marker == local_change_timestamp then
+    log.msg(log.debug, "cached change marker matches local change timestamp for image " .. tostring(image.id) .. "; reusing cached asset id " .. tostring(cached_id) .. " without metadata lookup")
+    asset_id = cached_id
+    replaced = true
+  end
+  local existing_asset_id = nil
+  local existing_asset = nil
+
+  if asset_id == nil and cached_id ~= nil then
+    log.msg(log.debug, "looking up cached asset id " .. tostring(cached_id) .. " for image " .. tostring(image.id))
+    local asset_details, asset_err = get_asset_details(cached_id)
+    if asset_details ~= nil then
+      existing_asset_id = cached_id
+      existing_asset = asset_details
+    else
+      log.msg(log.debug, "cached asset id " .. tostring(cached_id) .. " no longer exists on server (HTTP " .. tostring(asset_err) .. "); uploading new")
+    end
+  end
+
+  if existing_asset_id ~= nil and existing_asset ~= nil and existing_asset.isTrashed == true then
+    log.msg(log.debug, "existing remote asset is trashed; ignoring cached asset id " .. tostring(existing_asset_id) .. " and uploading a fresh copy")
+    existing_asset_id = nil
+    existing_asset = nil
+  end
+
+  local copied_album_ids = {}
+  local requested_album_mode = extra_data.album_mode or ALBUM_MODE_NONE
+  if existing_asset_id ~= nil and asset_id == nil
+      and (requested_album_mode == ALBUM_MODE_COPY_EXISTING or requested_album_mode == ALBUM_MODE_COPY_AND_TITLE) then
+    copied_album_ids = fetch_asset_album_ids(existing_asset_id)
+    log.msg(log.debug, "found " .. tostring(#copied_album_ids) .. " album(s) on existing asset " .. tostring(existing_asset_id) .. " to copy for image " .. tostring(image.id))
+  end
+
+  if asset_id ~= nil then
+    log.msg(log.debug, "using cached asset id " .. tostring(asset_id) .. " for image " .. tostring(image.id) .. "; skipping remote asset actions")
+  elseif existing_asset_id ~= nil then
+    if existing_asset_action == EXISTING_ASSET_ACTION_UPLOAD_NEW then
+      log.msg(log.debug, "existing-asset action is upload as new image; uploading independent copy, leaving existing asset id " .. tostring(existing_asset_id) .. " untouched")
+      asset_id = upload_image(image,filename)
+    elseif existing_asset_action == EXISTING_ASSET_ACTION_DELETE then
+      log.msg(log.debug, "existing-asset action is delete/trash; uploading replacement for existing asset id " .. tostring(existing_asset_id))
+      asset_id = upload_image(image,filename)
+      if asset_id ~= nil then
+        delete_asset(existing_asset_id)
+      end
+    else
+      local stacked_asset_id = create_stack_with_existing_asset(image,filename,existing_asset_id)
+      if stacked_asset_id ~= nil then
+        asset_id = stacked_asset_id
+        replaced = false
+        if existing_asset_action == EXISTING_ASSET_ACTION_DELETE_AND_STACK then
+          log.msg(log.debug, "existing-asset action is delete-and-stack; deleting existing asset id " .. tostring(existing_asset_id) .. " after stacking")
+          delete_asset(existing_asset_id)
+        end
+      else
+        log.msg(log.debug, "stack creation failed for existing asset id " .. tostring(existing_asset_id) .. ", falling back to standalone upload")
+        asset_id = upload_image(image,filename)
+        replaced = false
+        if asset_id ~= nil and existing_asset_action == EXISTING_ASSET_ACTION_DELETE_AND_STACK then
+          log.msg(log.debug, "delete-and-stack fallback path; deleting existing asset id " .. tostring(existing_asset_id) .. " after standalone upload")
+          delete_asset(existing_asset_id)
+        end
+      end
+    end
+  else
+    log.msg(log.debug, "no existing remote asset found for image " .. tostring(image.id) .. ", uploading new")
+    asset_id = upload_image(image,filename)
+  end
+
+  if asset_id == nil then 
+    log.msg(log.debug, "upload failed for image " .. tostring(image.id))
+    extra_data.error = "Error uploading some image"
+    return
+  end
+
+  if not replaced then
+    log.msg(log.debug, "caching asset id " .. tostring(asset_id) .. " for image " .. tostring(image.id))
+    set_cached_change_tag(image, image.change_timestamp)
+    set_cached_asset_id(image, asset_id)
+  end
+
+  if not replaced then
+    local album_mode = extra_data.album_mode or ALBUM_MODE_NONE
+    if album_mode == ALBUM_MODE_TITLE
+        or album_mode == ALBUM_MODE_COPY_AND_TITLE
+        or album_mode == ALBUM_MODE_USE_ALBUM_TITLE then
+      local album_name
+      if album_mode == ALBUM_MODE_USE_ALBUM_TITLE then
+        -- Uses darktable's own folder name for the image rather than the manual
+        -- title input box, which is hidden for this mode.
+        album_name = basename_from_path(image.path)
+      else
+        album_name = title_widget.text or ""
+      end
+      if album_name == "" then
+        log.msg(log.debug, "album mode requires an album name but none was available; skipping album assignment")
+      else
+        log.msg(log.debug, "album mode resolved album name '" .. tostring(album_name) .. "' for image " .. tostring(image.id))
+        local album_assets = extra_data.album_assets[album_name]
+        if album_assets == nil then
+          album_assets = {}
+          extra_data.album_assets[album_name] = album_assets
+        end
+        table.insert(album_assets,asset_id)
+        log.msg(log.debug, "queued asset " .. tostring(asset_id) .. " for album " .. tostring(album_name))
+      end
+    end
+
+    if album_mode == ALBUM_MODE_COPY_EXISTING or album_mode == ALBUM_MODE_COPY_AND_TITLE then
+      if #copied_album_ids == 0 then
+        log.msg(log.debug, "album copy mode selected but no albums found on existing asset for image " .. tostring(image.id))
+      else
+        for _,album_id in ipairs(copied_album_ids) do
+          queue_asset_for_album_id(extra_data, album_id, asset_id)
+          log.msg(log.debug, "queued asset " .. tostring(asset_id) .. " for existing album id " .. tostring(album_id))
+        end
+      end
+    else
+      log.msg(log.debug, "album mode is none; skipping album assignment for image " .. tostring(image.id))
+    end
+  end
+end
+
+local function finalize(storage,image_table,extra_data)
+  if extra_data.album_assets ~= nil then 
+    local album_count = 0
+    for _ in pairs(extra_data.album_assets) do
+      album_count = album_count + 1
+    end
+    log.msg(log.debug, "finalizing album updates for " .. tostring(album_count) .. " album(s)")
+    for album_name,album_assets in pairs(extra_data.album_assets) do
+      local album_id = find_album_id_by_name(album_name)
+      if album_id == nil then
+        log.msg(log.debug, "creating new album: " .. album_name)
+        call_immich_api("POST","albums",{albumName=album_name,assetIds=album_assets})
+      else
+        log.msg(log.debug, "adding assets to album: "..album_name)
+        call_immich_api("PUT","albums/"..album_id.."/assets",{ids=album_assets})
+      end
+    end
+  end
+  if extra_data.album_asset_updates ~= nil then
+    local album_update_count = 0
+    for _ in pairs(extra_data.album_asset_updates) do
+      album_update_count = album_update_count + 1
+    end
+    log.msg(log.debug, "finalizing copy-to-existing-album updates for " .. tostring(album_update_count) .. " album(s)")
+    for album_id,album_assets in pairs(extra_data.album_asset_updates) do
+      log.msg(log.debug, "adding assets to existing album id: " .. tostring(album_id))
+      call_immich_api("PUT","albums/"..album_id.."/assets",{ids=album_assets})
+    end
+  end
+  if extra_data.error ~= nil then
+    log.msg(log.debug, "finalizing with error: " .. tostring(extra_data.error))
+    log.msg(log.error, extra_data.error)
+  end
+  restore_log_level(extra_data.log_level)
+end
+
+local function destroy()
+  dt.destroy_storage("immich")
+end
+
+dt.preferences.register(
+   "immich","immich_server","string",
+    _("Immich server"),
+    _("The url of the Immich server to upload"),
+    "http://localhost:2283")
+
+dt.preferences.register(
+   "immich","immich_key","string",
+    _("Immich API key"),
+    _("A valid Immich API key"),
+    "<your api key>")
+
+dt.preferences.register(
+   "immich","default_album_mode","enum",
+    _("Default album mode"),
+    _("Default value of the 'Album mode' export option."),
+    ALBUM_MODE_LABELS[ALBUM_MODE_COPY_EXISTING],
+    table.unpack(ALBUM_MODE_LABELS))
+
+dt.preferences.register(
+   "immich","default_skip_unchanged","bool",
+    _("Default: Skip unchanged"),
+    _("Default value of the 'Skip unchanged' export option."),
+    true)
+
+dt.preferences.register(
+   "immich","default_existing_asset_action","enum",
+    _("Default re-export behavior"),
+    _("Default value of the 'Re-export Behavior' export option."),
+    EXISTING_ASSET_ACTION_LABELS[EXISTING_ASSET_ACTION_DELETE_AND_STACK],
+    table.unpack(EXISTING_ASSET_ACTION_LABELS))
+
+local default_album_mode = index_of_label(ALBUM_MODE_LABELS,
+    dt.preferences.read("immich", "default_album_mode", "enum")) or ALBUM_MODE_COPY_EXISTING
+local default_existing_asset_action = index_of_label(EXISTING_ASSET_ACTION_LABELS,
+    dt.preferences.read("immich", "default_existing_asset_action", "enum")) or EXISTING_ASSET_ACTION_DELETE_AND_STACK
+
+title_widget = dt.new_widget("entry") {
+    placeholder=_("No album")
+}
+album_mode_widget = dt.new_widget("combobox") {
+  label = _("Album mode"),
+  tooltip = _("Choose how exported assets are assigned to albums."),
+  selected = default_album_mode,
+  changed_callback = function(_)
+    update_album_title_row_visibility()
+  end,
+  table.unpack(ALBUM_MODE_LABELS)
+}
+skip_unchanged_widget = dt.new_widget("check_button") {
+  label = _("Skip unchanged"),
+  tooltip = _("Skip contacting the Immich server entirely when an image hasn't changed since its last export."),
+  value = dt.preferences.read("immich", "default_skip_unchanged", "bool")
+}
+existing_asset_action_widget = dt.new_widget("combobox") {
+  label = _("Re-export Behavior"),
+  tooltip = _("Choose what happens to the previous asset on the server when a changed image is re-exported."),
+  selected = default_existing_asset_action,
+  table.unpack(EXISTING_ASSET_ACTION_LABELS)
+}
+album_title_row_widget = dt.new_widget("box") {
+    orientation=horizontal,
+  dt.new_widget("label"){label = _("Album Title"), tooltip = _("Set the album title on Immich for the exported images.") },
+    title_widget
+}
+
+local widget = dt.new_widget("box") {
+  orientation=vertical,
+  album_mode_widget,
+  album_title_row_widget,
+  skip_unchanged_widget,
+  existing_asset_action_widget
+}
+
+update_album_title_row_visibility()
+
+dt.register_storage("immich",_("immich"),
+    store_image,
+    finalize,
+    nil,
+    initialize,
+    widget)
+
+local script_data = {}
+
+script_data.metadata = {
+  name = "immich",
+  purpose = _("upload all selected images to Immich server"),
+  author = "Daniel N. Hansten"
+}
+
+script_data.destroy = destroy -- function to destroy the script
+script_data.destroy_method = nil -- set to hide for libs since we can't destroy them completely yet, otherwise leave as nil
+script_data.restart = nil -- how to restart the (lib) script after it's been hidden - i.e. make it visible again
+script_data.show = nil -- only required for libs since the destroy_method only hides them
+
+return script_data
+--
+-- vim: shiftwidth=2 expandtab tabstop=2 cindent syntax=lua