feat: validate model capability before download

crates/tabby-download/src/lib.rs

@@ -2,7 +2,7 @@
 use std::{fs, io};
 
 use aim_downloader::{bar::WrappedBar, error::DownloadError, hash::HashChecker, https};
-use anyhow::{bail, Result};
+use anyhow::{bail, Context, Result};
 use tabby_common::registry::{parse_model_id, ModelInfo, ModelRegistry};
 use tokio_retry::{
     strategy::{jitter, ExponentialBackoff},
@@ -187,17 +187,58 @@ async fn download_file(
     Ok(())
 }
 
-pub async fn download_model(model_id: &str, prefer_local_file: bool) {
+pub enum ModelKind {
+    Embedding,
+    Completion,
+    Chat,
+}
+
+pub async fn download_model(model_id: &str, prefer_local_file: bool, kind: Option<ModelKind>) {
     let (registry, name) = parse_model_id(model_id);
 
     let registry = ModelRegistry::new(registry).await;
 
+    if let Some(kind) = kind {
+        let model_info = registry.get_model_info(name);
+        validate_model_kind(kind, model_info)
+            .context(
+                "Model validation has failed. For TabbyML models, please consult https://github.com/tabbyml/registry-tabby to locate the appropriate models.",
+            )
+            .unwrap();
+    }
+
     let handler = |err| panic!("Failed to fetch model '{}' due to '{}'", model_id, err);
     download_model_impl(&registry, name, prefer_local_file)
         .await
         .unwrap_or_else(handler)
 }
 
+fn validate_model_kind(kind: ModelKind, info: &ModelInfo) -> Result<()> {
+    match kind {
+        ModelKind::Embedding => Ok(()),
+        ModelKind::Completion => info
+            .prompt_template
+            .as_ref()
+            .ok_or_else(|| {
+                anyhow::anyhow!(
+                    "Model '{}' is not a completion model; it does not have a prompt template.",
+                    info.name
+                )
+            })
+            .map(|_| ()),
+        ModelKind::Chat => info
+            .chat_template
+            .as_ref()
+            .ok_or_else(|| {
+                anyhow::anyhow!(
+                    "Model '{}' is not a chat model, it does not have a chat template",
+                    info.name
+                )
+            })
+            .map(|_| ()),
+    }
+}
+
 #[cfg(test)]
 mod tests {
     // filter_download_address tests should be serial because they rely on environment variables

crates/tabby/src/download.rs

@@ -14,6 +14,6 @@ pub struct DownloadArgs {
 }
 
 pub async fn main(args: &DownloadArgs) {
-    download_model(&args.model, args.prefer_local_file).await;
+    download_model(&args.model, args.prefer_local_file, None).await;
     info!("model '{}' is ready", args.model);
 }

crates/tabby/src/serve.rs

@@ -10,6 +10,7 @@ use tabby_common::{
     config::{Config, ModelConfig},
     usage,
 };
+use tabby_download::ModelKind;
 use tabby_inference::ChatCompletionStream;
 use tokio::{sync::oneshot::Sender, time::sleep};
 use tower_http::timeout::TimeoutLayer;
@@ -212,15 +213,15 @@ pub async fn main(config: &Config, args: &ServeArgs) {
 
 async fn load_model(config: &Config) {
     if let Some(ModelConfig::Local(ref model)) = config.model.completion {
-        download_model_if_needed(&model.model_id).await;
+        download_model_if_needed(&model.model_id, ModelKind::Completion).await;
     }
 
     if let Some(ModelConfig::Local(ref model)) = config.model.chat {
-        download_model_if_needed(&model.model_id).await;
+        download_model_if_needed(&model.model_id, ModelKind::Chat).await;
     }
 
     if let ModelConfig::Local(ref model) = config.model.embedding {
-        download_model_if_needed(&model.model_id).await;
+        download_model_if_needed(&model.model_id, ModelKind::Embedding).await;
     }
 }
 

crates/tabby/src/services/model/mod.rs

@@ -2,7 +2,7 @@ use std::{fs, sync::Arc};
 
 pub use llama_cpp_server::PromptInfo;
 use tabby_common::config::ModelConfig;
-use tabby_download::download_model;
+use tabby_download::{download_model, ModelKind};
 use tabby_inference::{ChatCompletionStream, CodeGeneration, CompletionStream, Embedding};
 use tracing::info;
 
@@ -80,10 +80,10 @@ async fn load_completion_and_chat(
     (completion, prompt, chat)
 }
 
-pub async fn download_model_if_needed(model: &str) {
+pub async fn download_model_if_needed(model: &str, kind: ModelKind) {
     if fs::metadata(model).is_ok() {
         info!("Loading model from local path {}", model);
     } else {
-        download_model(model, true).await;
+        download_model(model, true, Some(kind)).await;
     }
 }