feat: add Scheduler provider + multi-provider UX fixes

Scheduler provider:
- Virtual provider (no external service) that emits SCHEDULED_MESSAGE
  events on user-defined intervals or cron expressions
- Custom variables stored in tracker filters, flattened into template context
- fire_count persists across triggers via tracker state
- APScheduler CronTrigger support for cron-mode schedules
- Default templates (EN+RU), seeded on startup

Multi-provider UX fixes:
- Tracking config hides Immich-specific sections (periodic, scheduled,
  memory, asset display) for non-Immich providers
- Command config driven by provider capabilities — hides commands/settings
  for providers without bot commands
- Template config hides empty "Scheduled Messages" group
- Test menu on tracker targets is provider-aware (Immich shows all 4 test
  types, others show only basic)
- Removed redundant Test button from tracker card
- System-owned tracking configs (user_id=0) seeded for Gitea + Scheduler
- Fixed ownership checks to allow system configs in tracker-target links
- Capabilities cache shared across template-configs and command-configs
- Command tracker bot selector uses EntitySelect instead of raw select
- Sample context includes Gitea + Scheduler variables for template preview

packages/core/src/notify_bridge_core/models/events.py

@@ -32,6 +32,9 @@ class EventType(str, Enum):
     PR_COMMENTED = "pr_commented"
     RELEASE_PUBLISHED = "release_published"
 
+    # Scheduler events
+    SCHEDULED_MESSAGE = "scheduled_message"
+
 
 @dataclass
 class ServiceEvent:

packages/core/src/notify_bridge_core/providers/base.py

@@ -16,6 +16,7 @@ class ServiceProviderType(str, Enum):
 
     IMMICH = "immich"
     GITEA = "gitea"
+    SCHEDULER = "scheduler"
 
 
 class ServiceProvider(ABC):

packages/core/src/notify_bridge_core/providers/capabilities.py

@@ -165,6 +165,25 @@ GITEA_CAPABILITIES = ProviderCapabilities(
     commands=[],
 )
 
+# ---------------------------------------------------------------------------
+# Scheduler provider capabilities
+# ---------------------------------------------------------------------------
+
+SCHEDULER_CAPABILITIES = ProviderCapabilities(
+    provider_type="scheduler",
+    display_name="Scheduler",
+    webhook_based=False,
+    supported_filters=[],
+    notification_slots=[
+        {"name": "message_scheduled_message", "description": "Scheduled message"},
+    ],
+    command_slots=[],
+    events=[
+        {"name": "scheduled_message", "description": "Scheduled event fired"},
+    ],
+    commands=[],
+)
+
 # ---------------------------------------------------------------------------
 # Registry
 # ---------------------------------------------------------------------------
@@ -172,6 +191,7 @@ GITEA_CAPABILITIES = ProviderCapabilities(
 _REGISTRY: dict[str, ProviderCapabilities] = {
     "immich": IMMICH_CAPABILITIES,
     "gitea": GITEA_CAPABILITIES,
+    "scheduler": SCHEDULER_CAPABILITIES,
 }
 
 

packages/core/src/notify_bridge_core/providers/scheduler/__init__.py

@@ -0,0 +1,14 @@
+"""Scheduler service provider implementation."""
+
+from notify_bridge_core.providers.base import ServiceProviderType
+from notify_bridge_core.templates.variables import registry
+
+from .provider import SchedulerServiceProvider, SCHEDULER_VARIABLES
+
+# Register Scheduler variables in the global registry
+registry.register_provider_variables(ServiceProviderType.SCHEDULER, SCHEDULER_VARIABLES)
+
+__all__ = [
+    "SchedulerServiceProvider",
+    "SCHEDULER_VARIABLES",
+]

packages/core/src/notify_bridge_core/providers/scheduler/provider.py

@@ -0,0 +1,157 @@
+"""Scheduler service provider — virtual provider that emits events on a schedule."""
+
+from __future__ import annotations
+
+import logging
+from datetime import datetime, timezone
+from typing import Any
+
+from notify_bridge_core.models.events import EventType, ServiceEvent
+from notify_bridge_core.providers.base import ServiceProvider, ServiceProviderType
+from notify_bridge_core.templates.variables import TemplateVariableDefinition
+
+_LOGGER = logging.getLogger(__name__)
+
+_WEEKDAYS = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"]
+
+SCHEDULER_VARIABLES: list[TemplateVariableDefinition] = [
+    TemplateVariableDefinition(
+        name="schedule_name",
+        type="string",
+        description="Name of the scheduled tracker",
+        example="Daily standup reminder",
+        provider_type=ServiceProviderType.SCHEDULER,
+    ),
+    TemplateVariableDefinition(
+        name="fire_count",
+        type="int",
+        description="How many times this schedule has fired",
+        example="42",
+        provider_type=ServiceProviderType.SCHEDULER,
+    ),
+    TemplateVariableDefinition(
+        name="current_date",
+        type="string",
+        description="Current date (formatted)",
+        example="22.03.2026",
+        provider_type=ServiceProviderType.SCHEDULER,
+    ),
+    TemplateVariableDefinition(
+        name="current_time",
+        type="string",
+        description="Current time (formatted)",
+        example="09:00",
+        provider_type=ServiceProviderType.SCHEDULER,
+    ),
+    TemplateVariableDefinition(
+        name="current_datetime",
+        type="string",
+        description="Current date and time (formatted)",
+        example="22.03.2026, 09:00 UTC",
+        provider_type=ServiceProviderType.SCHEDULER,
+    ),
+    TemplateVariableDefinition(
+        name="weekday",
+        type="string",
+        description="Day of the week",
+        example="Monday",
+        provider_type=ServiceProviderType.SCHEDULER,
+    ),
+    TemplateVariableDefinition(
+        name="custom_vars",
+        type="dict",
+        description="User-defined key-value pairs (also available as top-level variables)",
+        example='{"team": "Engineering", "channel": "#general"}',
+        provider_type=ServiceProviderType.SCHEDULER,
+    ),
+]
+
+
+class SchedulerServiceProvider(ServiceProvider):
+    """Virtual provider that generates events on a schedule.
+
+    No external service connection. The poll() method creates a
+    SCHEDULED_MESSAGE event with datetime info and custom variables.
+    """
+
+    provider_type = ServiceProviderType.SCHEDULER
+
+    def __init__(
+        self,
+        name: str = "Scheduler",
+        tracker_name: str = "",
+        custom_variables: dict[str, str] | None = None,
+        date_format: str = "%d.%m.%Y",
+        time_format: str = "%H:%M",
+        datetime_format: str = "%d.%m.%Y, %H:%M UTC",
+    ) -> None:
+        self._name = name
+        self._tracker_name = tracker_name
+        self._custom_variables = custom_variables or {}
+        self._date_format = date_format
+        self._time_format = time_format
+        self._datetime_format = datetime_format
+
+    async def connect(self) -> bool:
+        return True  # virtual provider — always connected
+
+    async def disconnect(self) -> None:
+        pass
+
+    async def poll(
+        self,
+        collection_ids: list[str],
+        tracker_state: dict[str, Any],
+    ) -> tuple[list[ServiceEvent], dict[str, Any]]:
+        now = datetime.now(timezone.utc)
+        # State uses {collection_id: {dict}} convention like other providers
+        sched_state = tracker_state.get("scheduler", {})
+        fire_count = sched_state.get("fire_count", 0) + 1
+
+        extra: dict[str, Any] = {
+            "schedule_name": self._tracker_name,
+            "fire_count": fire_count,
+            "current_date": now.strftime(self._date_format),
+            "current_time": now.strftime(self._time_format),
+            "current_datetime": now.strftime(self._datetime_format),
+            "weekday": _WEEKDAYS[now.weekday()],
+            "custom_vars": dict(self._custom_variables),
+        }
+        # Flatten custom variables at top level for easy template access
+        extra.update(self._custom_variables)
+
+        event = ServiceEvent(
+            event_type=EventType.SCHEDULED_MESSAGE,
+            provider_type=ServiceProviderType.SCHEDULER,
+            provider_name=self._name,
+            collection_id="scheduler",
+            collection_name=self._tracker_name,
+            timestamp=now,
+            extra=extra,
+        )
+
+        new_state = {
+            "scheduler": {
+                "name": self._tracker_name,
+                "fire_count": fire_count,
+                "asset_ids": [],
+                "pending_asset_ids": [],
+            },
+        }
+        return [event], new_state
+
+    def get_available_variables(self) -> list[TemplateVariableDefinition]:
+        return list(SCHEDULER_VARIABLES)
+
+    def get_provider_config_schema(self) -> dict[str, Any]:
+        return {
+            "type": "object",
+            "properties": {},
+            "required": [],
+        }
+
+    async def list_collections(self) -> list[dict[str, Any]]:
+        return []  # no collections concept
+
+    async def test_connection(self) -> dict[str, Any]:
+        return {"ok": True, "message": "Virtual provider — always available"}

packages/core/src/notify_bridge_core/templates/context.py

@@ -126,4 +126,14 @@ def build_template_context(
         if event.new_name:
             ctx.setdefault("new_album_name", event.new_name)
 
+    # Provider-specific defaults for Scheduler
+    if event.provider_type.value == "scheduler":
+        ctx.setdefault("schedule_name", event.collection_name)
+        ctx.setdefault("fire_count", event.extra.get("fire_count", 0))
+        ctx.setdefault("current_date", event.extra.get("current_date", ""))
+        ctx.setdefault("current_time", event.extra.get("current_time", ""))
+        ctx.setdefault("current_datetime", event.extra.get("current_datetime", ""))
+        ctx.setdefault("weekday", event.extra.get("weekday", ""))
+        ctx.setdefault("custom_vars", event.extra.get("custom_vars", {}))
+
     return ctx

packages/core/src/notify_bridge_core/templates/defaults/en/scheduled_message.jinja2

@@ -0,0 +1,7 @@
+🔔 <b>{{ schedule_name }}</b> (#{{ fire_count }})
+📅 {{ current_datetime }}
+{%- if custom_vars %}
+{%- for key, value in custom_vars.items() %}
+{{ key }}: {{ value }}
+{%- endfor %}
+{%- endif %}

packages/core/src/notify_bridge_core/templates/defaults/loader.py

@@ -33,6 +33,9 @@ PROVIDER_SLOT_FILE_MAP: dict[str, dict[str, str]] = {
         "message_pr_commented": "gitea_pr_commented.jinja2",
         "message_release_published": "gitea_release_published.jinja2",
     },
+    "scheduler": {
+        "message_scheduled_message": "scheduled_message.jinja2",
+    },
 }
 
 # Backward-compatible alias

packages/core/src/notify_bridge_core/templates/defaults/ru/scheduled_message.jinja2

@@ -0,0 +1,7 @@
+🔔 <b>{{ schedule_name }}</b> (#{{ fire_count }})
+📅 {{ current_datetime }}
+{%- if custom_vars %}
+{%- for key, value in custom_vars.items() %}
+{{ key }}: {{ value }}
+{%- endfor %}
+{%- endif %}