Simplify Telegram channel config with host-injected tunnel/webhook settings

The WASM channel no longer needs its own polling_enabled/tunnel_url settings.
Instead, the host injects tunnel_url and webhook_secret into the channel config
at runtime before start() is called.

Changes:
- Add update_config() method to WasmChannel for runtime config injection
- Simplify TelegramConfig to only have bot_username, respond_to_all_group_messages
- Host injects tunnel_url (from Settings) and webhook_secret (from secrets store)
- Channel checks if tunnel_url is present to determine webhook vs polling mode
- Add delete_webhook() for clean transition to polling mode when no tunnel

Co-Authored-By: Claude Opus 4.5 <[email protected]>

channels-src/telegram/src/lib.rs

@@ -177,7 +177,11 @@ struct TelegramMessageMetadata {
     is_private: bool,
 }
 
-/// Channel configuration from capabilities file.
+/// Channel configuration injected by host.
+///
+/// The host injects runtime values like tunnel_url and webhook_secret.
+/// The channel doesn't need to know about polling vs webhook mode - it just
+/// checks if tunnel_url is set to determine behavior.
 #[derive(Debug, Deserialize)]
 struct TelegramConfig {
     /// Bot username (without @) for mention detection in groups.
@@ -188,30 +192,17 @@ struct TelegramConfig {
     #[serde(default)]
     respond_to_all_group_messages: bool,
 
-    /// Whether to use polling instead of webhooks.
-    /// Automatically disabled if tunnel_url is set.
-    #[serde(default)]
-    polling_enabled: bool,
-
-    /// Polling interval in milliseconds (if polling enabled).
-    #[serde(default = "default_poll_interval")]
-    poll_interval_ms: u32,
-
-    /// Public tunnel URL for webhook mode (e.g., "https://abc123.ngrok.io").
+    /// Public tunnel URL for webhook mode (injected by host from global settings).
     /// When set, webhook mode is enabled and polling is disabled.
     #[serde(default)]
     tunnel_url: Option<String>,
 
-    /// Secret token for webhook validation.
+    /// Secret token for webhook validation (injected by host from secrets store).
     /// Telegram will include this in the X-Telegram-Bot-Api-Secret-Token header.
     #[serde(default)]
     webhook_secret: Option<String>,
 }
 
-fn default_poll_interval() -> u32 {
-    30000 // 30 seconds (minimum allowed)
-}
-
 // ============================================================================
 // Channel Implementation
 // ============================================================================
@@ -220,6 +211,11 @@ struct TelegramChannel;
 
 impl Guest for TelegramChannel {
     fn on_start(config_json: String) -> Result<ChannelConfig, String> {
+        channel_host::log(
+            channel_host::LogLevel::Debug,
+            &format!("Telegram channel config: {}", config_json),
+        );
+
         let config: TelegramConfig = serde_json::from_str(&config_json)
             .map_err(|e| format!("Failed to parse config: {}", e))?;
 
@@ -232,21 +228,21 @@ impl Guest for TelegramChannel {
             );
         }
 
-        // Determine mode: webhook or polling
-        // Webhook mode is enabled if tunnel_url is set, which disables polling
+        // Mode is determined by whether the host injected a tunnel_url
+        // If tunnel is configured, use webhooks. Otherwise, use polling.
         let webhook_mode = config.tunnel_url.is_some();
 
         if webhook_mode {
             channel_host::log(
                 channel_host::LogLevel::Info,
-                "Webhook mode enabled (polling disabled)",
+                "Webhook mode enabled (tunnel configured)",
             );
 
             // Register webhook with Telegram API
             if let Some(ref tunnel_url) = config.tunnel_url {
                 channel_host::log(
                     channel_host::LogLevel::Info,
-                    &format!("Registering webhook with Telegram API: {}", tunnel_url),
+                    &format!("Registering webhook: {}/webhook/telegram", tunnel_url),
                 );
 
                 if let Err(e) = register_webhook(tunnel_url, config.webhook_secret.as_deref()) {
@@ -254,28 +250,35 @@ impl Guest for TelegramChannel {
                         channel_host::LogLevel::Error,
                         &format!("Failed to register webhook: {}", e),
                     );
-                    // Continue anyway, the host will start the server
-                    // and Telegram will eventually receive updates
                 }
             }
+        } else {
+            channel_host::log(
+                channel_host::LogLevel::Info,
+                "Polling mode enabled (no tunnel configured)",
+            );
+
+            // Delete any existing webhook before polling
+            // Telegram doesn't allow getUpdates while a webhook is active
+            if let Err(e) = delete_webhook() {
+                channel_host::log(
+                    channel_host::LogLevel::Warn,
+                    &format!("Failed to delete webhook (may not exist): {}", e),
+                );
+            }
         }
 
-        // Configure polling only if not in webhook mode and polling is enabled
-        let poll = if !webhook_mode && config.polling_enabled {
-            channel_host::log(
-                channel_host::LogLevel::Info,
-                &format!("Polling enabled (interval: {}ms)", config.poll_interval_ms.max(30000)),
-            );
+        // Configure polling only if not in webhook mode
+        let poll = if !webhook_mode {
             Some(PollConfig {
-                interval_ms: config.poll_interval_ms.max(30000), // Enforce minimum
+                interval_ms: 30000, // 30 seconds minimum
                 enabled: true,
             })
         } else {
             None
         };
 
-        // Webhook secret validation is handled by the host (X-Telegram-Bot-Api-Secret-Token header)
-        // The require_secret flag tells the host to validate the secret_validated field
+        // Webhook secret validation is handled by the host
         let require_secret = config.webhook_secret.is_some();
 
         Ok(ChannelConfig {
@@ -507,9 +510,54 @@ impl Guest for TelegramChannel {
 }
 
 // ============================================================================
-// Webhook Registration
+// Webhook Management
 // ============================================================================
 
+/// Delete any existing webhook with Telegram API.
+///
+/// Called during on_start() when switching to polling mode.
+/// Telegram doesn't allow getUpdates while a webhook is active.
+fn delete_webhook() -> Result<(), String> {
+    let headers = serde_json::json!({
+        "Content-Type": "application/json"
+    });
+
+    let result = channel_host::http_request(
+        "POST",
+        "https://api.telegram.org/bot{TELEGRAM_BOT_TOKEN}/deleteWebhook",
+        &headers.to_string(),
+        None,
+    );
+
+    match result {
+        Ok(response) => {
+            if response.status != 200 {
+                let body_str = String::from_utf8_lossy(&response.body);
+                return Err(format!("HTTP {}: {}", response.status, body_str));
+            }
+
+            let api_response: TelegramApiResponse<bool> =
+                serde_json::from_slice(&response.body)
+                    .map_err(|e| format!("Failed to parse response: {}", e))?;
+
+            if !api_response.ok {
+                return Err(format!(
+                    "Telegram API error: {}",
+                    api_response.description.unwrap_or_else(|| "unknown".to_string())
+                ));
+            }
+
+            channel_host::log(
+                channel_host::LogLevel::Info,
+                "Webhook deleted successfully (switching to polling mode)",
+            );
+
+            Ok(())
+        }
+        Err(e) => Err(format!("HTTP request failed: {}", e)),
+    }
+}
+
 /// Register webhook URL with Telegram API.
 ///
 /// Called during on_start() when tunnel_url is configured.

src/channels/wasm/wrapper.rs

@@ -373,7 +373,8 @@ pub struct WasmChannel {
     capabilities: ChannelCapabilities,
 
     /// Channel configuration JSON (passed to on_start).
-    config_json: String,
+    /// Wrapped in RwLock to allow updating before start.
+    config_json: RwLock<String>,
 
     /// Channel configuration returned by on_start.
     channel_config: RwLock<Option<ChannelConfig>>,
@@ -420,7 +421,7 @@ impl WasmChannel {
             runtime,
             prepared,
             capabilities,
-            config_json,
+            config_json: RwLock::new(config_json),
             channel_config: RwLock::new(None),
             message_tx: Arc::new(RwLock::new(None)),
             pending_responses: RwLock::new(HashMap::new()),
@@ -432,6 +433,32 @@ impl WasmChannel {
         }
     }
 
+    /// Update the channel config before starting.
+    ///
+    /// Merges the provided values into the existing config JSON.
+    /// Call this before `start()` to inject runtime values like tunnel_url.
+    pub async fn update_config(&self, updates: HashMap<String, serde_json::Value>) {
+        let mut config_guard = self.config_json.write().await;
+
+        // Parse existing config
+        let mut config: HashMap<String, serde_json::Value> =
+            serde_json::from_str(&config_guard).unwrap_or_default();
+
+        // Merge updates
+        for (key, value) in updates {
+            config.insert(key, value);
+        }
+
+        // Serialize back
+        *config_guard = serde_json::to_string(&config).unwrap_or_else(|_| "{}".to_string());
+
+        tracing::debug!(
+            channel = %self.name,
+            config = %*config_guard,
+            "Updated channel config"
+        );
+    }
+
     /// Set a credential for URL injection.
     pub async fn set_credential(&self, name: &str, value: String) {
         self.credentials
@@ -590,7 +617,7 @@ impl WasmChannel {
         let runtime = Arc::clone(&self.runtime);
         let prepared = Arc::clone(&self.prepared);
         let capabilities = self.capabilities.clone();
-        let config_json = self.config_json.clone();
+        let config_json = self.config_json.read().await.clone();
         let timeout = self.runtime.config().callback_timeout;
         let channel_name = self.name.clone();
         let credentials = self.get_credentials().await;

src/main.rs

@@ -399,6 +399,36 @@ async fn main() -> anyhow::Result<()> {
 
                             let channel_arc = Arc::new(loaded.channel);
 
+                            // Inject runtime config into the channel (tunnel_url, webhook_secret)
+                            // This must be done before start() is called
+                            {
+                                let mut config_updates = std::collections::HashMap::new();
+
+                                if let Some(ref tunnel_url) = config.tunnel.public_url {
+                                    config_updates.insert(
+                                        "tunnel_url".to_string(),
+                                        serde_json::Value::String(tunnel_url.clone()),
+                                    );
+                                }
+
+                                if let Some(ref secret) = webhook_secret {
+                                    config_updates.insert(
+                                        "webhook_secret".to_string(),
+                                        serde_json::Value::String(secret.clone()),
+                                    );
+                                }
+
+                                if !config_updates.is_empty() {
+                                    channel_arc.update_config(config_updates).await;
+                                    tracing::info!(
+                                        channel = %channel_name,
+                                        has_tunnel = config.tunnel.public_url.is_some(),
+                                        has_webhook_secret = webhook_secret.is_some(),
+                                        "Injected runtime config into channel"
+                                    );
+                                }
+                            }
+
                             tracing::info!(
                                 channel = %channel_name,
                                 has_webhook_secret = webhook_secret.is_some(),
@@ -410,7 +440,7 @@ async fn main() -> anyhow::Result<()> {
                                 .register(
                                     Arc::clone(&channel_arc),
                                     endpoints,
-                                    webhook_secret,
+                                    webhook_secret.clone(),
                                     secret_header,
                                 )
                                 .await;