From d7436b8b9c1f3132b2ca1def6b1e22225a032854 Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Mon, 16 Mar 2026 19:28:13 -0400
Subject: [PATCH] llm: catch empty and rate-limited responses as errors

Empty stdout and Claude's rate limit message were silently returned
as successful 0-byte responses. Now detected and reported as errors.

Also skip transcript segments with fewer than 2 assistant messages
(rate-limited sessions, stub conversations).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 poc-memory/src/agents/knowledge.rs | 13 +++++++++++++
 poc-memory/src/agents/llm.rs       |  8 ++++++++
 2 files changed, 21 insertions(+)

diff --git a/poc-memory/src/agents/knowledge.rs b/poc-memory/src/agents/knowledge.rs
index e5cf23c..9a46ff1 100644
--- a/poc-memory/src/agents/knowledge.rs
+++ b/poc-memory/src/agents/knowledge.rs
@@ -754,6 +754,19 @@ pub fn select_conversation_fragments(n: usize) -> Vec<(String, String)> {
             if store.is_segment_mined(&session_id, seg_idx as u32, "observation") {
                 continue;
             }
+            // Skip segments with too few assistant messages (rate limits, errors)
+            let assistant_msgs = segment.iter()
+                .filter(|(_, role, _, _)| role == "assistant")
+                .count();
+            if assistant_msgs < 2 {
+                continue;
+            }
+            // Skip segments that are just rate limit errors
+            let has_rate_limit = segment.iter().any(|(_, _, text, _)|
+                text.contains("hit your limit") || text.contains("rate limit"));
+            if has_rate_limit && assistant_msgs < 3 {
+                continue;
+            }
             let text = format_segment(&segment, 8000);
             if text.len() > 500 {
                 let id = format!("{}.{}", session_id, seg_idx);
diff --git a/poc-memory/src/agents/llm.rs b/poc-memory/src/agents/llm.rs
index 4a0a742..099cd7d 100644
--- a/poc-memory/src/agents/llm.rs
+++ b/poc-memory/src/agents/llm.rs
@@ -152,6 +152,14 @@ fn call_model_with_tools(agent: &str, model: &str, prompt: &str,
             }
             if output.status.success() {
                 let response = String::from_utf8_lossy(&output.stdout).trim().to_string();
+                if response.is_empty() {
+                    log_usage(agent, model, prompt, "EMPTY", elapsed, false);
+                    return Err("claude returned empty response".into());
+                }
+                if response.contains(": You've hit your limit \u{00b7} resets") {
+                    log_usage(agent, model, prompt, "RATE_LIMITED", elapsed, false);
+                    return Err(format!("rate limited: {}", crate::util::first_n_chars(&response, 200)));
+                }
                 log_usage(agent, model, prompt, &response, elapsed, true);
                 Ok(response)
             } else {