feat(reminders): add generic webhook as a fourth reminder channel (#2952)

Replaces any Discord-specific reminder channel with a generic outbound
webhook channel. Users pick any saved Integration as the target and
supply a JSON payload template with {{title}} and {{message}}
placeholders — values are JSON-escaped before substitution. Works with
Discord, Slack, Teams, ntfy (JSON mode), or any service that accepts a
POST with a JSON body.

- `src/settings.py` — reminder_webhook_integration_id +
  reminder_webhook_payload_template defaults
- `routes/note_routes.py` — webhook delivery block; Integration lookup,
  template rendering, auth wiring; built-in preset defaults so
  discord_webhook works out of the box without a configured template;
  settings_override kwarg avoids test-button race condition
- `routes/auth_routes.py` — discord_webhook preset test handler
- `src/integrations.py` — discord_webhook preset with description +
  example templates; hides auth/key fields in the Integration form
- `src/builtin_actions.py` — webhook_sent delivery check
- `src/tool_implementations.py` — webhook aliases + enum updated
- `static/index.html` — Webhook channel option; Integration picker +
  payload template textarea
- `static/js/settings.js` — Integration list, populateWebhookIntegrations,
  syncChannelRows, hints, load/save, auto-fill preset templates,
  test-button override payload, hide auth/key for URL-auth presets

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

src/builtin_actions.py

@@ -1902,6 +1902,8 @@ async def action_check_email_urgency(owner: str, **kwargs) -> Tuple[str, bool]:
                     delivered = bool(dispatch_result.get("email_sent"))
                 elif channel == "ntfy":
                     delivered = bool(dispatch_result.get("ntfy_sent"))
+                elif channel == "webhook":
+                    delivered = bool(dispatch_result.get("webhook_sent"))
                 if delivered:
                     newly_notified.update(new_urgent)
                 else:

src/integrations.py

@@ -100,6 +100,19 @@ INTEGRATION_PRESETS: Dict[str, Dict[str, Any]] = {
             "  GET /{topic}/json?poll=1 — poll for messages"
         ),
     },
+    "discord_webhook": {
+        "name": "Discord Webhook",
+        "auth_type": "none",
+        "description": (
+            "Discord Incoming Webhook. Paste the full webhook URL (including the token) as the Base URL.\n"
+            "To get a URL: Discord server -> Server Settings -> Integrations -> Webhooks -> New Webhook -> Copy Webhook URL.\n"
+            "The secret is embedded in the URL — leave auth type as None.\n\n"
+            "Use this integration as the target in Settings -> Reminders -> Webhook channel.\n"
+            "Payload template examples:\n"
+            "  Simple:  {\"content\": \"{{title}}: {{message}}\"}\n"
+            "  Embed:   {\"embeds\": [{\"title\": \"{{title}}\", \"description\": \"{{message}}\", \"color\": 5793266}]}"
+        ),
+    },
     "vaultwarden": {
         "name": "Vaultwarden",
         "auth_type": "header",

src/settings.py

@@ -141,10 +141,17 @@ DEFAULT_SETTINGS = {
     # library can grow beyond this; cleanup/retirement is an explicit review flow.
     "skill_max_injected": 3,
     # Reminders
-    "reminder_channel": "browser",   # "browser" | "email" | "ntfy"
+    "reminder_channel": "browser",   # "browser" | "email" | "ntfy" | "webhook"
     "reminder_llm_synthesis": False,
     "reminder_ntfy_topic": "Reminders",
     "reminder_email_to": "",
+    # Generic outbound webhook channel: pick any saved Integration as the
+    # target and supply a JSON payload template. Use {{title}} and {{message}}
+    # as placeholders — they are JSON-escaped before substitution, so the
+    # rendered string is always valid JSON. Works with Discord, Slack, Teams,
+    # ntfy (JSON mode), or any service that accepts a POST with a JSON body.
+    "reminder_webhook_integration_id": "",
+    "reminder_webhook_payload_template": "",
     # Email triage scanner rules. Running/paused state and schedule live in
     # Tasks via the built-in `check_email_urgency` task.
     "urgent_email_prompt": (

src/tool_implementations.py

@@ -1566,6 +1566,8 @@ async def do_manage_settings(content: str, owner: Optional[str] = None) -> Dict:
             "image gen": "image_gen_enabled", "image generation": "image_gen_enabled",
             "reminder channel": "reminder_channel", "reminders": "reminder_channel",
             "ntfy topic": "reminder_ntfy_topic",
+            "webhook integration": "reminder_webhook_integration_id",
+            "webhook template": "reminder_webhook_payload_template", "webhook payload": "reminder_webhook_payload_template",
             "agent tool calls": "agent_max_tool_calls", "max tool calls": "agent_max_tool_calls",
             "agent timeout": "agent_stream_timeout_seconds", "stream timeout": "agent_stream_timeout_seconds",
             "token budget": "agent_input_token_budget", "input budget": "agent_input_token_budget",
@@ -1581,7 +1583,7 @@ async def do_manage_settings(content: str, owner: Optional[str] = None) -> Dict:
 
         _ENUMS = {
             "image_quality": ["low", "medium", "high"],
-            "reminder_channel": ["browser", "email", "ntfy"],
+            "reminder_channel": ["browser", "email", "ntfy", "webhook"],
         }
         def _coerce(value, default):
             if isinstance(default, bool):