Let each workflow watch the due date or the start date

Deck 1.18 added a start date to cards (Card::$startdate), so a workflow
no longer has to mean "overdue". Each rule now carries a date_field
('due' | 'start'), chosen in the settings form next to board and stacks.

Existing rules keep the due date: the new column's default supplies it
for every stored row, so there is no backfill step, and
Workflow::getDateFieldOrDue() covers entities that were never near the
database as well as hand-edited values. The controller is the one place
that rejects an unknown value instead of normalising it - a client
asking for a rule it would not get should hear about it.

The probe for the field is property_exists(), not method_exists():
Deck's entities declare no getter as real code - getStartdate(),
getDuedate(), even getId() all go through Entity::__call(), which
method_exists() ignores by definition. A method_exists() guard would
have been false on every Deck version and would have turned every
start-date rule into a silent no-op.

assertDeckAvailable() now also refuses Deck older than 1.18.0. That
floor cannot live in appinfo/info.xml - neither the server's nor the app
store's schema has an app-to-app dependency element - but
<nextcloud min-version="34"> already implies it, since 1.18.x is the
only Deck release line published for Nextcloud 34.

isOverdue() becomes hasPassed(): one function for both dates, since the
comparison and the argument against Deck's day-truncating
getDaysUntilDue() are identical for either.

Also carries a pending NcSelect icon-alignment fix that was already in
the working tree.

Bump to 34.1.0.

CLAUDE.md

@@ -4,7 +4,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 ## What this is
 
-A Nextcloud app (`workflow_deck_automation`, namespace `WorkflowDeckAutomation`) targeting **Nextcloud Hub 26 Spring (server 34.x)**. It lets each user configure, from their personal settings, automation "workflows" that move overdue [Deck](https://github.com/nextcloud/deck) cards from one stack to another, with optional assigned-user/label filters and an email notification. A background `Job` evaluates all enabled workflows on every cron pass.
+A Nextcloud app (`workflow_deck_automation`, namespace `WorkflowDeckAutomation`) targeting **Nextcloud Hub 26 Spring (server 34.x)**. It lets each user configure, from their personal settings, automation "workflows" that move [Deck](https://github.com/nextcloud/deck) cards from one stack to another once their due date or start date has passed, with optional assigned-user/label filters and an email notification. A background `Job` evaluates all enabled workflows on every cron pass.
 
 ## Non-negotiable architectural constraint
 
@@ -12,6 +12,27 @@ A Nextcloud app (`workflow_deck_automation`, namespace `WorkflowDeckAutomation`)
 
 All Deck access is funneled through `lib/Service/DeckIntegrationService.php` — it is the *only* class that references `OCA\Deck\*`. If you need new Deck data, extend that class rather than reaching into Deck internals from elsewhere. Every call in there is wrapped (`class_exists()` checks, `IAppManager::isEnabledForUser('deck', …)`, try/catch → `DeckUnavailableException`) because `OCA\Deck\*` is not a documented/stable public API — it has no `@since` markers and can change between Deck releases without notice.
 
+## `method_exists()` cannot see Deck's getters — use `property_exists()`
+
+`Card`, `Board`, `Label`, `Acl` and `Assignment` declare **no getters as real code**. `getStartdate()`, `getDuedate()`, `getDeletedAt()`, `getArchived()`, even `getId()` are `@method` docblocks resolved by `OCP\AppFramework\Db\Entity::__call()` (`Entity` itself declares neither `getId()` nor `setId()`). `method_exists()` ignores `__call()` by definition, so **every `method_exists($deckEntity, 'getSomething')` probe in this app is permanently false**, on every Deck version, and the guarded branch is dead code that fails open or closed without a sound.
+
+`DeckIntegrationService::getCardDate()` therefore probes `property_exists($card, 'startdate')` — the protected property declaration is visible, and it is exactly what `Entity::getter()` checks before throwing `BadFunctionCallException`. Use that shape for any new optional Deck field.
+
+**Known dead probes still in the tree** (each one a separate fix, none of them yet made — verify against a live instance before touching, since the symptoms are silent):
+
+- `getCardLabelIds()` / `extractParticipantUid()` — always return `[]`/`null`, so **label and assigned-user filters cannot match any card**, and ACL participants never reach the settings dropdown. Only the board owner survives, because `RelationalObject::getPrimaryKey()` *is* real code — which is why the bug is invisible on a private board (empty ACL, owner = the user themselves) and looks fixed.
+- `getActiveCardsInStack()`'s `getDeletedAt` check — trashed cards are moved.
+- `findStackIds()`'s `getDeletedAt` check — a board in the trash is not recognised as gone.
+- `isBoardHidden()` — dead, but masked by `getUserBoards(null, false)` doing the filtering server-side.
+
+## The Deck version floor lives in code, because info.xml cannot express it
+
+`DeckIntegrationService::MIN_DECK_VERSION` (`1.18.0`) plus the `version_compare()` in `assertDeckAvailable()` is the *only* enforcement point for "this app needs a recent Deck". Neither the server's `resources/app-info.xsd` nor the app store's `info.xsd` has an app-to-app dependency element — `<dependencies>` takes only `php`, `database`, `command`, `lib`, `owncloud`, `nextcloud`, `architecture`, `backend`. Don't go looking for a `<app min-version=…>`; it does not exist in either schema.
+
+`<nextcloud min-version="34" max-version="34"/>` already does most of the work and is the strictest pin available: **Deck 1.18.x is the only Deck release line declaring `>=34.0.0,<35.0.0`**, and 1.18.0 is exactly the release that added the card start date (`Card::$startdate`, PR #7749). So on any Nextcloud this app installs on, Deck already has that field, and 1.17.x cannot be enabled at all (its own `max-version` is 33, so a server upgrade to 34 disables it). What the version check still covers is a Deck dropped in by hand or checked out from git.
+
+`version_compare()` sorts `1.18.0-beta.x` *below* `1.18.0`. That is intended — pre-releases of that line may predate the field. Since `assertDeckAvailable()` is called from both the controller (→ `OCSPreconditionFailedException`, visible as an error on the settings page) and the runner (→ skip + info log), a too-old Deck degrades in both places instead of failing halfway through a card move.
+
 ## Per-user impersonation in the background job
 
 `RunWorkflowsJob` has no logged-in user by default and must evaluate workflows belonging to many different users within one PHP process. `lib/Service/WorkflowRunner.php` therefore groups workflows by owner and impersonates each owner in turn. **Impersonation here is two steps, and `IUserSession::setUser()` is the one that barely matters:**
@@ -27,7 +48,19 @@ In cron that is *never* the user being impersonated: `null` if any Deck-owned ba
 
 Consequence for `getUserBoards()`: `listBoardsForCurrentUser()` stays **request-only** anyway — Deck may already have cached board lists behind that field, and the job has no use for a board *list*; it asks `findStackIds()` about one known board id. Before using any other `OCA\Deck\*` service from the runner, check whether it carries a frozen `$userId` — the failure mode is silent and user-crossing, not an error.
 
-The filter logic (`WorkflowRunner::cardMatchesFilters()`, `::isOverdue()`, `::findDeadFilters()`) is deliberately `static` and side-effect-free so it's unit-testable without a real Deck installation — see `tests/Unit/Service/WorkflowRunnerFilterTest.php`. Keep new pure logic in that shape; it is the only part of this app that has tests at all.
+The filter logic (`WorkflowRunner::cardMatchesFilters()`, `::hasPassed()`, `::findDeadFilters()`) is deliberately `static` and side-effect-free so it's unit-testable without a real Deck installation — see `tests/Unit/Service/WorkflowRunnerFilterTest.php`. Keep new pure logic in that shape; it is the only part of this app that has tests at all.
+
+## Due date or start date, per workflow
+
+Each workflow carries a `date_field` (`'due'` | `'start'`, `Workflow::DATE_FIELD_*`) deciding which Deck card date it watches. `WorkflowRunner::hasPassed()` (formerly `isOverdue()`) is one function for both, because the comparison is identical — the raw timestamp against `$now` — and the whole argument against Deck's day-truncating `getDaysUntilDue()` applies unchanged to the start date. What differs is only the wording, in the UI and in `NotificationMailer`.
+
+Three places keep an unknown value from becoming a surprise trigger, and all three resolve **towards the due date**, because that is what every workflow meant before the choice existed:
+
+- the column default `'due'`, which is also the entire migration for existing rows (`Version1001Date20260825120000`, a separate step because `Version1000…` is wrapped in `hasTable()` and would never reach an existing install),
+- `Workflow::getDateFieldOrDue()`, for entities that were never near the database and for hand-edited rows,
+- `DeckIntegrationService::CARD_DATE_PROPERTIES`'s `?? DEFAULT_CARD_DATE`.
+
+The controller is the exception: it *rejects* an unknown `dateField` instead of normalising it, since a client asking for a rule it would not get should hear about it.
 
 ## Workflows are auto-disabled when their Deck targets vanish
 

README.md

@@ -1,6 +1,8 @@
 # Deck Workflow-Automatisierung
 
-Nextcloud-App für **Nextcloud Hub 26 Spring (Server 34.x)**, die überfällige Karten der [Deck](https://github.com/nextcloud/deck)-App automatisch von einem Stapel in einen anderen verschiebt und optional eine E-Mail-Benachrichtigung verschickt.
+Nextcloud-App für **Nextcloud Hub 26 Spring (Server 34.x)**, die Karten der [Deck](https://github.com/nextcloud/deck)-App automatisch von einem Stapel in einen anderen verschiebt, sobald ihr Fälligkeits- oder Startdatum erreicht ist, und optional eine E-Mail-Benachrichtigung verschickt.
+
+Setzt **Deck ab 1.18.0** voraus (die Version, die das Startdatum eingeführt hat) — auf Nextcloud 34 ist das automatisch erfüllt, da 1.18.x die einzige dort freigegebene Deck-Reihe ist.
 
 Ersetzt das früher genutzte eigenständige PHP-Cron-Skript durch eine vollwertige App mit Oberfläche in den **persönlichen Einstellungen** — jeder Nutzer kann dort seine eigenen Regeln ("Workflows") anlegen, ohne Admin-Rechte oder Server-Zugriff zu benötigen.
 
@@ -9,7 +11,8 @@ Ersetzt das früher genutzte eigenständige PHP-Cron-Skript durch eine vollwerti
 Pro Workflow lässt sich konfigurieren:
 
 - Quell-Board und Quell-Stapel
-- Ziel-Stapel, in den überfällige Karten verschoben werden
+- Ziel-Stapel, in den die Karten verschoben werden
+- **auslösendes Datum: Fälligkeitsdatum oder Startdatum der Karte** (Karten ohne das gewählte Datum werden nie verschoben; Regeln aus älteren Versionen laufen unverändert auf dem Fälligkeitsdatum)
 - optionaler Filter auf zugewiesene Benutzer (Karte muss **mindestens einem** der gewählten Benutzer zugewiesen sein)
 - optionaler Filter auf Labels/Tags (Karte muss **mindestens eines** der gewählten Labels haben)
 - Checkbox: E-Mail-Benachrichtigung an den Workflow-Besitzer, sobald eine Karte verschoben wurde

appinfo/info.xml

@@ -4,31 +4,37 @@
     <id>workflow_deck_automation</id>
     <name lang="de">Deck Workflow-Automatisierung</name>
     <name lang="en">Deck Workflow Automation</name>
-    <summary lang="de">Verschiebt überfällige Deck-Karten automatisch anhand konfigurierbarer Regeln</summary>
-    <summary lang="en">Automatically moves overdue Deck cards based on configurable rules</summary>
+    <summary lang="de">Verschiebt Deck-Karten automatisch anhand konfigurierbarer Regeln</summary>
+    <summary lang="en">Automatically moves Deck cards based on configurable rules</summary>
     <description lang="de"><![CDATA[
 Diese App erlaubt es jedem Nutzer, in den persönlichen Einstellungen eigene Automatisierungs-Workflows für die Deck-App anzulegen:
 
 * Quell-Board und Quell-Stapel wählen
-* Ziel-Stapel wählen, in den überfällige Karten verschoben werden
+* Ziel-Stapel wählen, in den die Karten verschoben werden
+* je Regel wählen, ob das Fälligkeits- oder das Startdatum der Karte ausgewertet wird
 * optional nach zugewiesenen Benutzern filtern
 * optional nach Labels/Tags filtern
 * optional eine E-Mail-Benachrichtigung an sich selbst aktivieren
 
-Ein Hintergrundjob prüft regelmäßig alle aktiven Workflows und verschiebt Karten, deren Fälligkeitsdatum überschritten wurde, ausschließlich über die internen PHP-Klassen der Deck-App (keine HTTP/OCS-Aufrufe).
+Ein Hintergrundjob prüft regelmäßig alle aktiven Workflows und verschiebt Karten, deren gewähltes Datum in der Vergangenheit liegt, ausschließlich über die internen PHP-Klassen der Deck-App (keine HTTP/OCS-Aufrufe).
+
+Voraussetzung: Nextcloud 34 und die Deck-App ab Version 1.18.0 – die einzige Deck-Reihe, die für Nextcloud 34 freigegeben ist.
 ]]></description>
     <description lang="en"><![CDATA[
 This app lets every user configure their own Deck automation workflows from Personal settings:
 
 * pick a source board and source stack
-* pick a destination stack overdue cards get moved to
+* pick a destination stack the cards get moved to
+* pick, per rule, whether the card's due date or its start date is evaluated
 * optionally filter by assigned users
 * optionally filter by labels/tags
 * optionally enable an email notification to themselves
 
-A background job periodically evaluates all enabled workflows and moves cards whose due date has passed, using Deck's own internal PHP classes only (no HTTP/OCS calls).
+A background job periodically evaluates all enabled workflows and moves cards whose chosen date lies in the past, using Deck's own internal PHP classes only (no HTTP/OCS calls).
+
+Requires Nextcloud 34 and Deck 1.18.0 or newer - the only Deck release line supported on Nextcloud 34.
 ]]></description>
-    <version>34.0.2</version>
+    <version>34.1.0</version>
     <licence>agpl</licence>
     <author mail="patrick@niebel.ing">Patrick Niebeling</author>
     <namespace>WorkflowDeckAutomation</namespace>

lib/Controller/WorkflowController.php

@@ -56,14 +56,15 @@ class WorkflowController extends OCSController {
 		int $targetStackId,
 		array $filterUserIds = [],
 		array $filterLabelIds = [],
+		string $dateField = Workflow::DATE_FIELD_DUE,
 		bool $notifyEmail = false,
 		bool $enabled = true,
 	): DataResponse {
-		$this->validate($title, $boardId, $sourceStackId, $targetStackId);
+		$this->validate($title, $boardId, $sourceStackId, $targetStackId, $dateField);
 
 		$workflow = new Workflow();
 		$workflow->setUserId($this->currentUserId());
-		$this->applyFields($workflow, $title, $boardId, $sourceStackId, $targetStackId, $filterUserIds, $filterLabelIds, $notifyEmail, $enabled);
+		$this->applyFields($workflow, $title, $boardId, $sourceStackId, $targetStackId, $filterUserIds, $filterLabelIds, $dateField, $notifyEmail, $enabled);
 
 		$workflow = $this->workflowMapper->insert($workflow);
 		return new DataResponse($workflow->jsonSerialize(), Http::STATUS_CREATED);
@@ -82,10 +83,11 @@ class WorkflowController extends OCSController {
 		int $targetStackId,
 		array $filterUserIds = [],
 		array $filterLabelIds = [],
+		string $dateField = Workflow::DATE_FIELD_DUE,
 		bool $notifyEmail = false,
 		bool $enabled = true,
 	): DataResponse {
-		$this->validate($title, $boardId, $sourceStackId, $targetStackId);
+		$this->validate($title, $boardId, $sourceStackId, $targetStackId, $dateField);
 
 		try {
 			$workflow = $this->workflowMapper->findForUser($id, $this->currentUserId());
@@ -93,7 +95,7 @@ class WorkflowController extends OCSController {
 			throw new OCSNotFoundException('Workflow not found');
 		}
 
-		$this->applyFields($workflow, $title, $boardId, $sourceStackId, $targetStackId, $filterUserIds, $filterLabelIds, $notifyEmail, $enabled);
+		$this->applyFields($workflow, $title, $boardId, $sourceStackId, $targetStackId, $filterUserIds, $filterLabelIds, $dateField, $notifyEmail, $enabled);
 		$workflow = $this->workflowMapper->update($workflow);
 
 		return new DataResponse($workflow->jsonSerialize());
@@ -147,13 +149,19 @@ class WorkflowController extends OCSController {
 		}
 	}
 
-	private function validate(string $title, int $boardId, int $sourceStackId, int $targetStackId): void {
+	private function validate(string $title, int $boardId, int $sourceStackId, int $targetStackId, string $dateField): void {
 		if (trim($title) === '') {
 			throw new OCSBadRequestException('Title must not be empty');
 		}
 		if ($sourceStackId === $targetStackId) {
 			throw new OCSBadRequestException('Source and target stack must differ');
 		}
+		// Rejected rather than silently normalised to 'due': a client sending
+		// something else is asking for a rule it would not get, and the runner
+		// falls back to the due date without a word.
+		if (!in_array($dateField, Workflow::DATE_FIELDS, true)) {
+			throw new OCSBadRequestException('Unknown date field: ' . $dateField);
+		}
 
 		// Reject references to boards or stacks that are gone (or were never
 		// the user's) instead of storing a workflow that can only fail later.
@@ -190,6 +198,7 @@ class WorkflowController extends OCSController {
 		int $targetStackId,
 		array $filterUserIds,
 		array $filterLabelIds,
+		string $dateField,
 		bool $notifyEmail,
 		bool $enabled,
 	): void {
@@ -199,6 +208,7 @@ class WorkflowController extends OCSController {
 		$workflow->setTargetStackId($targetStackId);
 		$workflow->setFilterUserIds($filterUserIds === [] ? null : json_encode(array_values($filterUserIds)));
 		$workflow->setFilterLabelIds($filterLabelIds === [] ? null : json_encode(array_values($filterLabelIds)));
+		$workflow->setDateField($dateField);
 		$workflow->setNotifyEmail($notifyEmail);
 		$workflow->setEnabled($enabled);
 	}

lib/Db/Workflow.php

@@ -22,6 +22,8 @@ use OCP\DB\Types;
  * @method void setFilterUserIds(?string $filterUserIds)
  * @method string|null getFilterLabelIds()
  * @method void setFilterLabelIds(?string $filterLabelIds)
+ * @method string|null getDateField()
+ * @method void setDateField(string $dateField)
  * @method bool getNotifyEmail()
  * @method void setNotifyEmail(bool $notifyEmail)
  * @method bool getEnabled()
@@ -30,6 +32,14 @@ use OCP\DB\Types;
  * @method void setLastRun(?\DateTime $lastRun)
  */
 class Workflow extends Entity implements \JsonSerializable {
+	/** Deck's `Card::$duedate` — the card is picked up once it is overdue. */
+	public const DATE_FIELD_DUE = 'due';
+
+	/** Deck's `Card::$startdate` — the card is picked up once its start date has been reached. */
+	public const DATE_FIELD_START = 'start';
+
+	public const DATE_FIELDS = [self::DATE_FIELD_DUE, self::DATE_FIELD_START];
+
 	protected $userId;
 	protected $title;
 	protected $boardId;
@@ -37,6 +47,7 @@ class Workflow extends Entity implements \JsonSerializable {
 	protected $targetStackId;
 	protected $filterUserIds;
 	protected $filterLabelIds;
+	protected $dateField;
 	protected $notifyEmail;
 	protected $enabled;
 	protected $lastRun;
@@ -50,11 +61,29 @@ class Workflow extends Entity implements \JsonSerializable {
 		$this->addType('targetStackId', Types::INTEGER);
 		$this->addType('filterUserIds', Types::STRING);
 		$this->addType('filterLabelIds', Types::STRING);
+		$this->addType('dateField', Types::STRING);
 		$this->addType('notifyEmail', Types::BOOLEAN);
 		$this->addType('enabled', Types::BOOLEAN);
 		$this->addType('lastRun', Types::DATETIME);
 	}
 
+	/**
+	 * The date field to evaluate, never anything else.
+	 *
+	 * Rows written before the column existed carry 'due' from the schema
+	 * default, but a freshly constructed entity holds `null` and a hand-edited
+	 * row could hold anything. Falling back to the due date keeps the old
+	 * behaviour for every value that is not explicitly the start date — the
+	 * safe direction, since 'due' is what every workflow meant before this
+	 * choice existed.
+	 *
+	 * @return self::DATE_FIELD_*
+	 */
+	public function getDateFieldOrDue(): string {
+		$field = $this->getDateField();
+		return in_array($field, self::DATE_FIELDS, true) ? $field : self::DATE_FIELD_DUE;
+	}
+
 	/**
 	 * @return string[]
 	 */
@@ -90,6 +119,7 @@ class Workflow extends Entity implements \JsonSerializable {
 			'targetStackId' => $this->getTargetStackId(),
 			'filterUserIds' => $this->getFilterUserIdsArray(),
 			'filterLabelIds' => $this->getFilterLabelIdsArray(),
+			'dateField' => $this->getDateFieldOrDue(),
 			'notifyEmail' => (bool)$this->getNotifyEmail(),
 			'enabled' => (bool)$this->getEnabled(),
 			'lastRun' => $this->getLastRun()?->format(\DateTimeInterface::ATOM),

lib/Migration/Version1001Date20260825120000.php

@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\WorkflowDeckAutomation\Migration;
+
+use Closure;
+use OCA\WorkflowDeckAutomation\Db\Workflow;
+use OCP\DB\ISchemaWrapper;
+use OCP\DB\Types;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+/**
+ * Adds the per-workflow choice between Deck's due date and its start date.
+ *
+ * A separate migration rather than an edit to Version1000...: that one is
+ * wrapped in `if (!$schema->hasTable(...))`, so changing it would only ever
+ * reach fresh installs.
+ *
+ * The `default` is what migrates the existing rows — every workflow written
+ * before this release was evaluated against the due date, and the column
+ * default gives exactly that without a backfill step.
+ */
+class Version1001Date20260825120000 extends SimpleMigrationStep {
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+
+		if (!$schema->hasTable('wfda_workflows')) {
+			return null;
+		}
+
+		$table = $schema->getTable('wfda_workflows');
+		if ($table->hasColumn('date_field')) {
+			return null;
+		}
+
+		$table->addColumn('date_field', Types::STRING, [
+			'notnull' => true,
+			'length' => 16,
+			'default' => Workflow::DATE_FIELD_DUE,
+		]);
+
+		return $schema;
+	}
+}

lib/Service/DeckIntegrationService.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace OCA\WorkflowDeckAutomation\Service;
 
+use DateTimeInterface;
 use OCA\Deck\Db\BoardMapper;
 use OCA\Deck\Db\Card;
 use OCA\Deck\Db\CardMapper;
@@ -35,6 +36,25 @@ use Throwable;
 class DeckIntegrationService {
 	private const DECK_APP_ID = 'deck';
 
+	/**
+	 * Oldest Deck this app will talk to.
+	 *
+	 * Deck 1.18.0 is the release that added the card start date
+	 * (`Card::$startdate`, PR #7749), which the start-date workflows read.
+	 * The floor cannot live in appinfo/info.xml: neither the server's
+	 * app-info.xsd nor the app store's info.xsd has an app-to-app dependency
+	 * element, only <nextcloud>.
+	 *
+	 * That pin does most of the work anyway — Deck 1.18.x is the only release
+	 * line declaring `>=34.0.0,<35.0.0`, so on the Nextcloud 34 this app
+	 * requires, every installable Deck already carries the field. What is left
+	 * for this check is a Deck put in place by hand or from git.
+	 *
+	 * version_compare() sorts `1.18.0-beta.x` *below* `1.18.0`, and that is
+	 * intended: the betas of that line may predate the field.
+	 */
+	private const MIN_DECK_VERSION = '1.18.0';
+
 	/**
 	 * Deck's Acl::PERMISSION_TYPE_* values, inlined so this class keeps
 	 * working (degrading to "treat it as a user") if Deck ever moves or
@@ -68,11 +88,31 @@ class DeckIntegrationService {
 		'OCA\Deck\Activity\ActivityManager',
 	];
 
+	/**
+	 * `Workflow::DATE_FIELD_*` mapped to the property on Deck's Card entity.
+	 * Kept here rather than on the Workflow so this class stays the only one
+	 * that has to know what Deck calls its columns.
+	 */
+	private const CARD_DATE_PROPERTIES = [
+		'due' => 'duedate',
+		'start' => 'startdate',
+	];
+
+	private const DEFAULT_CARD_DATE = 'due';
+
 	/**
 	 * @var list<array{ReflectionProperty, object, ?string}>
 	 */
 	private array $identityRestore = [];
 
+	/**
+	 * Card properties already reported as missing, so the warning in
+	 * getCardDate() is one line per process instead of one per card.
+	 *
+	 * @var array<string, true>
+	 */
+	private array $reportedMissingCardProperties = [];
+
 	public function __construct(
 		private IAppManager $appManager,
 		private IUserManager $userManager,
@@ -166,6 +206,16 @@ class DeckIntegrationService {
 		if (!$this->appManager->isEnabledForUser(self::DECK_APP_ID, $user)) {
 			throw new DeckUnavailableException('Deck is not enabled for user ' . $user->getUID());
 		}
+
+		$version = $this->appManager->getAppVersion(self::DECK_APP_ID);
+		if ($version === '' || version_compare($version, self::MIN_DECK_VERSION, '<')) {
+			throw new DeckUnavailableException(sprintf(
+				'Deck %s is installed, but %s or newer is required',
+				$version !== '' ? $version : '(unknown version)',
+				self::MIN_DECK_VERSION,
+			));
+		}
+
 		if (!class_exists(CardService::class) || !class_exists(BoardService::class) || !class_exists(StackService::class)) {
 			throw new DeckUnavailableException('Deck internal classes are not available');
 		}
@@ -487,7 +537,7 @@ class DeckIntegrationService {
 			// *returns* CardDetails wrappers whose own fields (duedate, stackId, ...) were never
 			// copied from the wrapped card - only its overridden jsonSerialize() reads through to
 			// them. Capturing that return value here made every card's getDuedate()/getDaysUntilDue()
-			// resolve to null, so isOverdue() was always false and no workflow ever matched a card.
+			// resolve to null, so hasPassed() was always false and no workflow ever matched a card.
 			// Keep using the original, now-enriched $cards instead.
 			$cardService->enrichCards($cards);
 
@@ -500,6 +550,45 @@ class DeckIntegrationService {
 		}, []);
 	}
 
+	/**
+	 * The card date a workflow is evaluated against: Deck's due date or its
+	 * start date, per `Workflow::DATE_FIELD_*`. Anything unrecognised reads the
+	 * due date, which is what every workflow meant before the choice existed.
+	 *
+	 * The guard is `property_exists()`, deliberately, and this is the one thing
+	 * to get right here: **`method_exists()` cannot see Deck's getters.**
+	 * `Card`, `Board`, `Label`, `Acl` and `Assignment` declare none of them as
+	 * real code — `getStartdate()`, `getDuedate()`, even `getId()` all go
+	 * through `OCP\AppFramework\Db\Entity::__call()`, and `method_exists()`
+	 * ignores `__call()` by definition. A `method_exists($card, 'getStartdate')`
+	 * probe would therefore be false on *every* Deck version and silently turn
+	 * every start-date workflow into a no-op. `property_exists()` sees the
+	 * protected `$startdate` declaration and is exactly what `Entity::getter()`
+	 * checks internally before throwing.
+	 *
+	 * In practice the property is always there — `assertDeckAvailable()`
+	 * enforces Deck >= MIN_DECK_VERSION, which is the release that added it —
+	 * so this branch is a backstop for a hand-installed Deck, loud enough to be
+	 * found in the log rather than silently matching nothing.
+	 */
+	public function getCardDate(Card $card, string $dateField): ?DateTimeInterface {
+		$property = self::CARD_DATE_PROPERTIES[$dateField] ?? self::CARD_DATE_PROPERTIES[self::DEFAULT_CARD_DATE];
+
+		if (!property_exists($card, $property)) {
+			if (!isset($this->reportedMissingCardProperties[$property])) {
+				$this->reportedMissingCardProperties[$property] = true;
+				$this->logger->warning(
+					'This Deck version has no Card::$' . $property . '; workflows using it cannot match any card',
+					['app' => 'workflow_deck_automation'],
+				);
+			}
+			return null;
+		}
+
+		$value = $property === 'startdate' ? $card->getStartdate() : $card->getDuedate();
+		return $value instanceof DateTimeInterface ? $value : null;
+	}
+
 	/**
 	 * @return string[]
 	 */

lib/Service/NotificationMailer.php

@@ -55,10 +55,19 @@ class NotificationMailer {
 			$template->setSubject($this->l10n->t('Deck card moved: %s', [$card->getTitle()]));
 			$template->addHeader();
 			$template->addHeading($this->l10n->t('A card was moved automatically'), false);
-			$template->addBodyText($this->l10n->t(
-				'The card "%1$s" was moved because it is overdue (workflow "%2$s").',
-				[$card->getTitle(), $workflow->getTitle()],
-			));
+			// Two whole strings rather than one sentence with an interpolated
+			// reason: the trigger is the point of the mail, and a translator
+			// needs to see it in the sentence to get the grammar right.
+			$reason = $workflow->getDateFieldOrDue() === Workflow::DATE_FIELD_START
+				? $this->l10n->t(
+					'The card "%1$s" was moved because its start date has been reached (workflow "%2$s").',
+					[$card->getTitle(), $workflow->getTitle()],
+				)
+				: $this->l10n->t(
+					'The card "%1$s" was moved because it is overdue (workflow "%2$s").',
+					[$card->getTitle(), $workflow->getTitle()],
+				);
+			$template->addBodyText($reason);
 			// Single-argument addBodyText() runs htmlspecialchars() itself, so
 			// these board- and stack-titles (user input) are safe as-is —
 			// unlike the description below, which passes both parts.

lib/Service/WorkflowRunner.php

@@ -17,7 +17,8 @@ use Psr\Log\LoggerInterface;
 use Throwable;
 
 /**
- * Evaluates all enabled workflows and moves overdue cards.
+ * Evaluates all enabled workflows and moves the cards whose watched date -
+ * Deck's due date or its start date, per workflow - has passed.
  *
  * This runner has to evaluate rules for many different users within a
  * single background-job process, so workflows are grouped by owner and
@@ -167,9 +168,10 @@ class WorkflowRunner {
 		$targets = null;
 
 		$now = $this->timeFactory->getDateTime();
+		$dateField = $workflow->getDateFieldOrDue();
 
 		foreach ($cards as $card) {
-			if (!self::isOverdue($card->getDuedate(), $now)) {
+			if (!self::hasPassed($this->deckService->getCardDate($card, $dateField), $now)) {
 				continue;
 			}
 
@@ -179,11 +181,12 @@ class WorkflowRunner {
 				continue;
 			}
 
-			$this->logger->info('Card {card} ("{title}") matches workflow {id}; moving to stack {target}.', [
+			$this->logger->info('Card {card} ("{title}") matches workflow {id} on its {dateField} date; moving to stack {target}.', [
 				'app' => 'workflow_deck_automation',
 				'card' => $card->getId(),
 				'title' => $card->getTitle(),
 				'id' => $workflow->getId(),
+				'dateField' => $dateField,
 				'target' => $workflow->getTargetStackId(),
 			]);
 
@@ -323,16 +326,21 @@ class WorkflowRunner {
 	}
 
 	/**
-	 * Compares the card's actual due timestamp against $now instead of Deck's own
+	 * Whether the card date a workflow watches - its due date or its start date,
+	 * see Workflow::DATE_FIELD_* - lies in the past. A card without that date set
+	 * is never picked up.
+	 *
+	 * Compares the card's actual timestamp against $now instead of Deck's own
 	 * Card::getDaysUntilDue(), which truncates both sides to midnight before diffing
 	 * (DateInterval's %a is a whole-day count) and therefore reports 0 - not overdue -
 	 * for any card whose due time has already passed today. That silently held back
 	 * every card for up to 24h after it actually fell due; comparing the raw datetime
 	 * instead matches what Deck's own UI shows (e.g. "vor 2 Stunden") and has no
-	 * day-rounding step to get wrong.
+	 * day-rounding step to get wrong. The same reasoning applies unchanged to the
+	 * start date, which is why this is one function and not two.
 	 */
-	public static function isOverdue(?DateTimeInterface $duedate, DateTimeInterface $now): bool {
-		return $duedate !== null && $duedate < $now;
+	public static function hasPassed(?DateTimeInterface $cardDate, DateTimeInterface $now): bool {
+		return $cardDate !== null && $cardDate < $now;
 	}
 
 	/**

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "workflow_deck_automation",
-	"version": "34.0.2",
+	"version": "34.1.0",
 	"private": true,
 	"type": "module",
 	"description": "Automates moving overdue Deck cards between stacks, configurable per user.",

src/PersonalSettings.vue

@@ -1,7 +1,7 @@
 <template>
 	<NcSettingsSection
 		name="Deck Workflow-Automatisierung"
-		description="Verschiebt überfällige Karten aus einem Deck-Stapel automatisch in einen anderen Stapel. Ein Hintergrundjob prüft die Regeln alle paar Minuten.">
+		description="Verschiebt Karten automatisch aus einem Deck-Stapel in einen anderen, sobald ihr Fälligkeits- oder Startdatum erreicht ist. Ein Hintergrundjob prüft die Regeln alle paar Minuten.">
 		<NcNoteCard v-if="loadError" type="error">
 			{{ loadError }}
 		</NcNoteCard>
@@ -17,6 +17,7 @@
 						<th>Titel</th>
 						<th>Von Stapel</th>
 						<th>Nach Stapel</th>
+						<th>Auslöser</th>
 						<th>Filter</th>
 						<th>E-Mail</th>
 						<th>Aktiv</th>
@@ -33,6 +34,7 @@
 						</td>
 						<td>{{ stackLabel(workflow.boardId, workflow.sourceStackId) }}</td>
 						<td>{{ stackLabel(workflow.boardId, workflow.targetStackId) }}</td>
+						<td>{{ dateFieldLabel(workflow.dateField) }}</td>
 						<td>
 							<span v-if="!workflow.filterUserIds.length && !workflow.filterLabelIds.length">–</span>
 							<span v-else>
@@ -92,6 +94,34 @@
 					:disabled="!form.boardId"
 					placeholder="Ziel-Stapel wählen" />
 
+				<fieldset class="wfda-fieldset">
+					<legend>Auslösendes Datum</legend>
+					<!--
+						v-model + value + type="radio" + a shared name is the
+						@nextcloud/vue 9 radio API: v-model carries the group's
+						current value, value the one this button stands for. Do
+						not reach for :checked.sync here - Vue 3 dropped .sync,
+						and it would silently never update.
+					-->
+					<NcCheckboxRadioSwitch
+						v-model="form.dateField"
+						value="due"
+						name="wfda-date-field"
+						type="radio">
+						Fälligkeitsdatum überschritten
+					</NcCheckboxRadioSwitch>
+					<NcCheckboxRadioSwitch
+						v-model="form.dateField"
+						value="start"
+						name="wfda-date-field"
+						type="radio">
+						Startdatum erreicht
+					</NcCheckboxRadioSwitch>
+					<p class="wfda-hint">
+						Karten ohne das gewählte Datum werden nie verschoben.
+					</p>
+				</fieldset>
+
 				<NcSelect
 					v-model="form.filterUserIds"
 					input-label="Nur für zugewiesene Benutzer (optional)"
@@ -257,11 +287,16 @@ function emptyForm() {
 		targetStackId: null,
 		filterUserIds: [],
 		filterLabelIds: [],
+		dateField: 'due',
 		notifyEmail: false,
 		enabled: true,
 	}
 }
 
+function dateFieldLabel(dateField) {
+	return dateField === 'start' ? 'Startdatum' : 'Fälligkeit'
+}
+
 function stackLabel(boardId, stackId) {
 	const stacks = stacksByBoard[boardId]
 	if (!stacks) {
@@ -386,6 +421,8 @@ async function editWorkflow(workflow) {
 		targetStackId: workflow.targetStackId,
 		filterUserIds: [...workflow.filterUserIds],
 		filterLabelIds: [...workflow.filterLabelIds],
+		// Workflows stored before this field existed come back without it.
+		dateField: workflow.dateField || 'due',
 		notifyEmail: workflow.notifyEmail,
 		enabled: workflow.enabled,
 	})
@@ -498,4 +535,38 @@ onMounted(loadAll)
 	display: flex;
 	gap: 8px;
 }
+
+.wfda-fieldset {
+	display: flex;
+	flex-direction: column;
+	gap: 4px;
+	/* The form already draws its own frame; the browser default would put a
+	   second box around just this group. */
+	border: none;
+	padding: 0;
+	margin: 0;
+}
+
+.wfda-fieldset legend {
+	font-weight: bold;
+	margin-bottom: 4px;
+}
+
+.wfda-hint {
+	color: var(--color-text-maxcontrast);
+	font-size: 0.9em;
+}
+
+/*
+ * NcSelect positions the clear/open icons (.vs__actions) absolutely relative
+ * to the outer .v-select wrapper, while the dropdown menu itself opens
+ * relative to .vs__dropdown-toggle (its $refs.toggle) — normally the same
+ * box, but any width mismatch between the two (e.g. from global Nextcloud
+ * input styles bleeding into the scoped component) shifts the icons off the
+ * visible border of single-value selects like Board/Quell-/Ziel-Stapel.
+ * Anchoring both to .vs__dropdown-toggle keeps them in sync.
+ */
+:deep(.v-select.select:not(.vs--multiple) .vs__dropdown-toggle) {
+	position: relative;
+}
 </style>

tests/Unit/Db/WorkflowTest.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\WorkflowDeckAutomation\Tests\Unit\Db;
+
+use OCA\WorkflowDeckAutomation\Db\Workflow;
+use PHPUnit\Framework\TestCase;
+
+class WorkflowTest extends TestCase {
+	public function testDateFieldDefaultsToDueWhenUnset(): void {
+		// The column default covers rows written before date_field existed,
+		// but an entity built in PHP has never been near the database.
+		$this->assertSame(Workflow::DATE_FIELD_DUE, (new Workflow())->getDateFieldOrDue());
+	}
+
+	public function testDateFieldIsKeptWhenKnown(): void {
+		$workflow = new Workflow();
+
+		$workflow->setDateField(Workflow::DATE_FIELD_START);
+		$this->assertSame(Workflow::DATE_FIELD_START, $workflow->getDateFieldOrDue());
+
+		$workflow->setDateField(Workflow::DATE_FIELD_DUE);
+		$this->assertSame(Workflow::DATE_FIELD_DUE, $workflow->getDateFieldOrDue());
+	}
+
+	public function testUnknownDateFieldFallsBackToDue(): void {
+		// A hand-edited row must not silently switch a workflow to a trigger
+		// nobody configured; the due date is what every workflow meant before
+		// this choice existed.
+		$workflow = new Workflow();
+		$workflow->setDateField('whenever');
+
+		$this->assertSame(Workflow::DATE_FIELD_DUE, $workflow->getDateFieldOrDue());
+	}
+
+	public function testDateFieldIsSerialisedForTheSettingsUi(): void {
+		$workflow = new Workflow();
+		$workflow->setDateField(Workflow::DATE_FIELD_START);
+
+		$this->assertSame(Workflow::DATE_FIELD_START, $workflow->jsonSerialize()['dateField']);
+	}
+}

tests/Unit/Service/WorkflowRunnerFilterTest.php

@@ -9,30 +9,30 @@ use OCA\WorkflowDeckAutomation\Service\WorkflowRunner;
 use PHPUnit\Framework\TestCase;
 
 class WorkflowRunnerFilterTest extends TestCase {
-	public function testIsOverdueReturnsFalseWithoutDueDate(): void {
-		$this->assertFalse(WorkflowRunner::isOverdue(null, new DateTimeImmutable('2026-01-15 12:00:00')));
+	public function testHasPassedReturnsFalseWithoutADate(): void {
+		$this->assertFalse(WorkflowRunner::hasPassed(null, new DateTimeImmutable('2026-01-15 12:00:00')));
 	}
 
-	public function testIsOverdueReturnsFalseForFutureDueDate(): void {
+	public function testHasPassedReturnsFalseForAFutureDate(): void {
 		$now = new DateTimeImmutable('2026-01-15 12:00:00');
-		$this->assertFalse(WorkflowRunner::isOverdue($now->modify('+1 hour'), $now));
-		$this->assertFalse(WorkflowRunner::isOverdue($now->modify('+3 days'), $now));
+		$this->assertFalse(WorkflowRunner::hasPassed($now->modify('+1 hour'), $now));
+		$this->assertFalse(WorkflowRunner::hasPassed($now->modify('+3 days'), $now));
 	}
 
-	public function testIsOverdueReturnsTrueForPastDueDate(): void {
+	public function testHasPassedReturnsTrueForAPastDate(): void {
 		$now = new DateTimeImmutable('2026-01-15 12:00:00');
-		$this->assertTrue(WorkflowRunner::isOverdue($now->modify('-1 hour'), $now));
-		$this->assertTrue(WorkflowRunner::isOverdue($now->modify('-30 days'), $now));
+		$this->assertTrue(WorkflowRunner::hasPassed($now->modify('-1 hour'), $now));
+		$this->assertTrue(WorkflowRunner::hasPassed($now->modify('-30 days'), $now));
 	}
 
-	public function testIsOverdueReturnsTrueForADueTimeEarlierTheSameDay(): void {
+	public function testHasPassedReturnsTrueForATimeEarlierTheSameDay(): void {
 		// Regression: comparing whole calendar days (as Deck's own
 		// Card::getDaysUntilDue() does) reports a card due earlier today as
 		// "0 days until due", not overdue, until the calendar date rolls
 		// over - holding every card back for up to 24h after it actually
-		// fell due. isOverdue() must compare the real timestamps instead.
+		// fell due. hasPassed() must compare the real timestamps instead.
 		$now = new DateTimeImmutable('2026-01-15 12:00:00');
-		$this->assertTrue(WorkflowRunner::isOverdue(new DateTimeImmutable('2026-01-15 06:00:00'), $now));
+		$this->assertTrue(WorkflowRunner::hasPassed(new DateTimeImmutable('2026-01-15 06:00:00'), $now));
 	}
 
 	public function testNoFiltersMatchesAnyCard(): void {