agent2: Expand auto-retries for completion errors (#39787)

This PR expands our automatic retry behavior for certain classes of
completion errors (e.g., rate limit errors).

Previously this was only available when using burn mode.

We now auto-retry when:

- Using the Zed provider while on a token-based plan
- Using the Zed provider while on a legacy plan with burn mode enabled
- Using a non-Zed provider

Release Notes:

- Expanded automatic retry behavior for errors in the Agent. Errors
classified as "retryable" (such as rate limit errors) will now
automatically be retried when:
  - Using the Zed provider while on a token-based plan
  - Using the Zed provider while on a legacy plan with burn mode enabled
  - Using a non-Zed provider

---------

Co-authored-by: David Kleingeld <davidsk@zed.dev>

crates/agent2/src/thread.rs

@@ -15,10 +15,11 @@ use agent_settings::{
 use anyhow::{Context as _, Result, anyhow};
 use assistant_tool::adapt_schema_to_format;
 use chrono::{DateTime, Utc};
-use client::{ModelRequestUsage, RequestUsage};
-use cloud_llm_client::{CompletionIntent, CompletionRequestStatus, UsageLimit};
+use client::{ModelRequestUsage, RequestUsage, UserStore};
+use cloud_llm_client::{CompletionIntent, CompletionRequestStatus, Plan, UsageLimit};
 use collections::{HashMap, HashSet, IndexMap};
 use fs::Fs;
+use futures::stream;
 use futures::{
     FutureExt,
     channel::{mpsc, oneshot},
@@ -34,7 +35,7 @@ use language_model::{
     LanguageModelImage, LanguageModelProviderId, LanguageModelRegistry, LanguageModelRequest,
     LanguageModelRequestMessage, LanguageModelRequestTool, LanguageModelToolResult,
     LanguageModelToolResultContent, LanguageModelToolSchemaFormat, LanguageModelToolUse,
-    LanguageModelToolUseId, Role, SelectedModel, StopReason, TokenUsage,
+    LanguageModelToolUseId, Role, SelectedModel, StopReason, TokenUsage, ZED_CLOUD_PROVIDER_ID,
 };
 use project::{
     Project,
@@ -585,6 +586,7 @@ pub struct Thread {
     pending_title_generation: Option<Task<()>>,
     summary: Option<SharedString>,
     messages: Vec<Message>,
+    user_store: Entity<UserStore>,
     completion_mode: CompletionMode,
     /// Holds the task that handles agent interaction until the end of the turn.
     /// Survives across multiple requests as the model performs tool calls and
@@ -641,6 +643,7 @@ impl Thread {
             pending_title_generation: None,
             summary: None,
             messages: Vec::new(),
+            user_store: project.read(cx).user_store(),
             completion_mode: AgentSettings::get_global(cx).preferred_completion_mode,
             running_turn: None,
             pending_message: None,
@@ -820,6 +823,7 @@ impl Thread {
             pending_title_generation: None,
             summary: db_thread.detailed_summary,
             messages: db_thread.messages,
+            user_store: project.read(cx).user_store(),
             completion_mode: db_thread.completion_mode.unwrap_or_default(),
             running_turn: None,
             pending_message: None,
@@ -1249,12 +1253,12 @@ impl Thread {
             );
 
             log::debug!("Calling model.stream_completion, attempt {}", attempt);
-            let mut events = model
-                .stream_completion(request, cx)
-                .await
-                .map_err(|error| anyhow!(error))?;
+
+            let (mut events, mut error) = match model.stream_completion(request, cx).await {
+                Ok(events) => (events, None),
+                Err(err) => (stream::empty().boxed(), Some(err)),
+            };
             let mut tool_results = FuturesUnordered::new();
-            let mut error = None;
             while let Some(event) = events.next().await {
                 log::trace!("Received completion event: {:?}", event);
                 match event {
@@ -1302,8 +1306,10 @@ impl Thread {
 
             if let Some(error) = error {
                 attempt += 1;
-                let retry =
-                    this.update(cx, |this, _| this.handle_completion_error(error, attempt))??;
+                let retry = this.update(cx, |this, cx| {
+                    let user_store = this.user_store.read(cx);
+                    this.handle_completion_error(error, attempt, user_store.plan())
+                })??;
                 let timer = cx.background_executor().timer(retry.duration);
                 event_stream.send_retry(retry);
                 timer.await;
@@ -1330,8 +1336,23 @@ impl Thread {
         &mut self,
         error: LanguageModelCompletionError,
         attempt: u8,
+        plan: Option<Plan>,
     ) -> Result<acp_thread::RetryStatus> {
-        if self.completion_mode == CompletionMode::Normal {
+        let Some(model) = self.model.as_ref() else {
+            return Err(anyhow!(error));
+        };
+
+        let auto_retry = if model.provider_id() == ZED_CLOUD_PROVIDER_ID {
+            match plan {
+                Some(Plan::V2(_)) => true,
+                Some(Plan::V1(_)) => self.completion_mode == CompletionMode::Burn,
+                None => false,
+            }
+        } else {
+            true
+        };
+
+        if !auto_retry {
             return Err(anyhow!(error));
         }