From 385e1716b72341beef2cefe7b6cdc17cf3d9354a Mon Sep 17 00:00:00 2001
From: tlongwell-block <109685178+tlongwell-block@users.noreply.github.com>
Date: Tue, 12 May 2026 13:57:02 -0400
Subject: [PATCH] agent+acp: preserve session on retriable agent errors (#544)

---
 crates/sprout-acp/src/pool.rs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/crates/sprout-acp/src/pool.rs b/crates/sprout-acp/src/pool.rs
index 9ed753bbd..b489f394d 100644
--- a/crates/sprout-acp/src/pool.rs
+++ b/crates/sprout-acp/src/pool.rs
@@ -1157,8 +1157,12 @@ pub async fn run_prompt_task(
         }
         Err(e) => {
             tracing::error!(target: "pool::prompt", "session_prompt error: {e}");
-            // Invalidate only the affected session.
-            agent.state.invalidate(&source);
+            // AgentError means the agent caught a problem before mutating
+            // session state (e.g. bad LLM response). The session is healthy —
+            // don't invalidate it. Other errors may have corrupted state.
+            if !matches!(e, AcpError::AgentError(_)) {
+                agent.state.invalidate(&source);
+            }
             let _ = result_tx.send(PromptResult {
                 agent,
                 source,