feat: add Feishu/Lark WASM channel plugin (#1110)

part of #1046

  - Implement Feishu Event Subscription v2.0 webhook (URL verification + im.message.receive_v1)
  - Token exchange via workspace-cached app credentials with 5-min pre-expiry refresh
  - Host-side secret injection into config JSON (setup.rs) so WASM can access app_id/app_secret without env vars
  - Reply and broadcast via /open-apis/im/v1/messages
  - Enforce allow_from user filtering in message handler
  - DM pairing flow with owner_id restriction
  - Dual API base support: open.feishu.cn (Feishu) / open.larksuite.com (Lark)
  - Registry manifest, bundled channel entry, messaging bundle integration
  - Strip raw config_json debug log to prevent secret leakage

src/channels/wasm/bundled.rs

@@ -22,6 +22,7 @@ const KNOWN_CHANNELS: &[(&str, &str)] = &[
     ("slack", "slack_channel"),
     ("discord", "discord_channel"),
     ("whatsapp", "whatsapp_channel"),
+    ("feishu", "feishu_channel"),
 ];
 
 /// Names of known channels that can be installed.

src/channels/wasm/setup.rs

@@ -161,6 +161,13 @@ async fn register_channel(
             config_updates.insert("owner_id".to_string(), serde_json::json!(owner_id));
         }
 
+        // Inject channel-specific secrets into config for channels that need
+        // credentials in API request bodies (e.g., Feishu token exchange).
+        // The credential injection system only replaces placeholders in URLs
+        // and headers, so channels like Feishu that exchange app_id + app_secret
+        // for a tenant token need the raw values in their config.
+        inject_channel_secrets_into_config(&channel_name, secrets_store, &mut config_updates).await;
+
         if !config_updates.is_empty() {
             channel_arc.update_config(config_updates).await;
             tracing::info!(
@@ -348,3 +355,62 @@ pub async fn inject_channel_credentials(
 
     Ok(count)
 }
+
+/// Inject channel-specific secrets into the config JSON.
+///
+/// Some channels (e.g., Feishu) need raw credential values in their config
+/// because they perform token exchanges that require secrets in the HTTP
+/// request body. The standard credential injection system only replaces
+/// placeholders in URLs and headers, so this function fills config fields
+/// that map to secret names.
+///
+/// Mapping: for a channel named "feishu", secrets `feishu_app_id` and
+/// `feishu_app_secret` are injected as config keys `app_id` and `app_secret`.
+async fn inject_channel_secrets_into_config(
+    channel_name: &str,
+    secrets_store: &Option<Arc<dyn SecretsStore + Send + Sync>>,
+    config_updates: &mut std::collections::HashMap<String, serde_json::Value>,
+) {
+    // Map of (config_key, secret_name) pairs per channel.
+    let secret_config_mappings: &[(&str, &str)] = match channel_name {
+        "feishu" => &[
+            ("app_id", "feishu_app_id"),
+            ("app_secret", "feishu_app_secret"),
+        ],
+        _ => return,
+    };
+
+    let Some(secrets) = secrets_store else {
+        return;
+    };
+
+    for &(config_key, secret_name) in secret_config_mappings {
+        match secrets.get_decrypted("default", secret_name).await {
+            Ok(decrypted) => {
+                config_updates.insert(
+                    config_key.to_string(),
+                    serde_json::Value::String(decrypted.expose().to_string()),
+                );
+                tracing::debug!(
+                    channel = %channel_name,
+                    config_key = %config_key,
+                    "Injected secret into channel config"
+                );
+            }
+            Err(_) => {
+                // Also try environment variable fallback.
+                let env_name = secret_name.to_uppercase();
+                if let Ok(val) = std::env::var(&env_name)
+                    && !val.is_empty()
+                {
+                    config_updates.insert(config_key.to_string(), serde_json::Value::String(val));
+                    tracing::debug!(
+                        channel = %channel_name,
+                        config_key = %config_key,
+                        "Injected secret from env into channel config"
+                    );
+                }
+            }
+        }
+    }
+}