stub letta completion command

src-tauri/Cargo.lock

···
 ]
 
 [[package]]
+name = "eventsource-stream"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "74fef4569247a5f429d9156b9d0a2599914385dd189c539334c625d8099d90ab"
+dependencies = [
+ "futures-core",
+ "nom",
+ "pin-project-lite",
+]
+
+[[package]]
 name = "fastrand"
 version = "2.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
···
 version = "0.3.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f90f7dce0722e95104fcb095585910c0977252f286e354b5e3bd38902cd99988"
+
+[[package]]
+name = "futures-timer"
+version = "3.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f288b0a4f20f9a56b5d1da57e2227c661b7b16168e2f72365f57b63326e29b24"
 
 [[package]]
 name = "futures-util"
···
 checksum = "6877bb514081ee2a7ff5ef9de3281f14a4dd4bceac4c09388074a6b5df8a139a"
 
 [[package]]
+name = "minimal-lexical"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
+
+[[package]]
 name = "miniz_oxide"
 version = "0.8.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
···
  "futures-util",
  "keyring",
  "reqwest",
+ "reqwest-eventsource",
  "serde",
  "serde_json",
  "strum",
···
 checksum = "72ef4a56884ca558e5ddb05a1d1e7e1bfd9a68d9ed024c21704cc98872dae1bb"
 
 [[package]]
+name = "nom"
+version = "7.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d273983c5a657a70a3e8f2a01329822f3b8c8172b73826411a55751e404a0a4a"
+dependencies = [
+ "memchr",
+ "minimal-lexical",
+]
+
+[[package]]
 name = "num-conv"
 version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
···
  "wasm-streams",
  "web-sys",
  "webpki-roots",
+]
+
+[[package]]
+name = "reqwest-eventsource"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "632c55746dbb44275691640e7b40c907c16a2dc1a5842aa98aaec90da6ec6bde"
+dependencies = [
+ "eventsource-stream",
+ "futures-core",
+ "futures-timer",
+ "mime",
+ "nom",
+ "pin-project-lite",
+ "reqwest",
+ "thiserror 1.0.69",
 ]
 
 [[package]]

src-tauri/Cargo.toml

···
 tauri-plugin-store = "2"
 tauri-plugin-http = "2"
 reqwest = { version = "0.12.23", features = ["json"] }
+reqwest-eventsource = "0.6.0"
 
 [target.'cfg(not(any(target_os = "android", target_os = "ios")))'.dependencies]
 tauri-plugin-positioner = "2"

src-tauri/src/letta/commands.rs

···
 
     Ok(id)
 }
+
+#[tauri::command]
+pub async fn start_llm_completion(
+    state: tauri::State<'_, AppState>,
+    message: String,
+) -> Result<(), ()> {
+    state.letta_manager.start_completion(message).await;
+
+    Ok(())
+}

src-tauri/src/letta/mod.rs

···
 use std::sync::Arc;
 
+use futures_util::StreamExt;
 use reqwest::Client;
+use reqwest_eventsource::{Event, EventSource};
 use serde::{Deserialize, Serialize};
 use serde_json::json;
 use strum::{Display, EnumString};
···
                 out
             }
             Err(_) => Vec::new(),
+        }
+    }
+
+    pub async fn start_completion(&self, msg: String) {
+        match self
+            .secrets_manager
+            .get_secret(crate::secrets::SecretName::LettaApiKey)
+        {
+            Ok(api_key) => {
+                let base_url = self.base_url.lock().await.to_owned();
+                let agent_id = self.base_url.lock().await.to_owned();
+                let req = self
+                    .http_client
+                    .post(format!("{base_url}/v1/agents/{agent_id}/messages/stream"))
+                    .header("Authorization", format!("Bearer {api_key}"))
+                    .header("Content-Type", "application/json")
+                    .json(&json!({
+                        "messages": [
+                            {
+                                "role": "user",
+                                "content": [ msg ]
+                            }
+                        ],
+                        "stream_tokens": true
+                    }));
+
+                let mut source =
+                    EventSource::new(req).expect("could not convert request to event source");
+
+                while let Some(event) = source.next().await {
+                    match event {
+                        Ok(Event::Open) => println!("stream opened"),
+                        Ok(Event::Message(msg)) => println!("got stream message: {:?}", msg),
+                        Err(err) => {
+                            eprintln!("got stream error: {}", err);
+                            source.close();
+                        }
+                    }
+                }
+            }
+            Err(err) => eprintln!("could not fetch Letta API key: {}", err),
         }
     }
 }

src-tauri/src/lib.rs

···
             letta::commands::set_letta_base_url,
             letta::commands::get_letta_agent_id,
             letta::commands::set_letta_agent_id,
+            letta::commands::start_llm_completion,
             secrets::commands::has_secret,
             secrets::commands::set_secret,
             secrets::commands::delete_secret,