fix: retry + stderr capture + pacing in triage/extractor

Both scripts now:
- Retry up to 3x with 2s/4s exponential backoff on transient
  failures (rate limits, capacity spikes)
- Capture claude CLI stderr in the error message (200 char cap)
  instead of just the exit code — diagnostics actually useful now
- Sleep 0.5s between calls to avoid bursting the backend

Context: last batch run hit 100% failure in triage (every call
exit 1) after 40% failure in extraction. claude CLI worked fine
immediately after, so the failures were capacity/rate-limit
transients. With retry + pacing these batches should complete
cleanly now. 439 candidates are already in the queue waiting
for triage.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/batch_llm_extract_live.py

@@ -126,22 +126,34 @@ def extract_one(prompt, response, project, model, timeout_s):
         user_message,
     ]
 
-    try:
-        completed = subprocess.run(
-            args, capture_output=True, text=True,
-            timeout=timeout_s, cwd=get_sandbox_cwd(),
-            encoding="utf-8", errors="replace",
-        )
-    except subprocess.TimeoutExpired:
-        return [], "timeout"
-    except Exception as exc:
-        return [], f"subprocess_error: {exc}"
+    # Retry with exponential backoff on transient failures (rate limits etc)
+    import time as _time
+    last_error = ""
+    for attempt in range(3):
+        if attempt > 0:
+            _time.sleep(2 ** attempt)  # 2s, 4s
+        try:
+            completed = subprocess.run(
+                args, capture_output=True, text=True,
+                timeout=timeout_s, cwd=get_sandbox_cwd(),
+                encoding="utf-8", errors="replace",
+            )
+        except subprocess.TimeoutExpired:
+            last_error = "timeout"
+            continue
+        except Exception as exc:
+            last_error = f"subprocess_error: {exc}"
+            continue
 
-    if completed.returncode != 0:
-        return [], f"exit_{completed.returncode}"
+        if completed.returncode == 0:
+            raw = (completed.stdout or "").strip()
+            return parse_candidates(raw, project), ""
 
-    raw = (completed.stdout or "").strip()
-    return parse_candidates(raw, project), ""
+        # Capture stderr for diagnostics (truncate to 200 chars)
+        stderr = (completed.stderr or "").strip()[:200]
+        last_error = f"exit_{completed.returncode}: {stderr}" if stderr else f"exit_{completed.returncode}"
+
+    return [], last_error
 
 
 def parse_candidates(raw, interaction_project):
@@ -192,10 +204,14 @@ def main():
     total_persisted = 0
     errors = 0
 
-    for summary in interaction_summaries:
+    import time as _time
+    for ix, summary in enumerate(interaction_summaries):
         resp_chars = summary.get("response_chars", 0) or 0
         if resp_chars < 50:
             continue
+        # Light pacing between calls to avoid bursting the claude CLI
+        if ix > 0:
+            _time.sleep(0.5)
         iid = summary["id"]
         try:
             raw = api_get(