diff --git a/plugins/claude-code/scripts/run-sleep.sh b/plugins/claude-code/scripts/run-sleep.sh
index e46e212..310d8de 100755
--- a/plugins/claude-code/scripts/run-sleep.sh
+++ b/plugins/claude-code/scripts/run-sleep.sh
@@ -30,12 +30,17 @@ if [ -z "${REPO_ROOT:-}" ]; then
 fi
 
 PY=""
-for cand in python3.12 python3.11 python3.10 python3; do
-  if command -v "$cand" >/dev/null 2>&1; then
-    ver="$("$cand" -c 'import sys; print("%d%d" % sys.version_info[:2])' 2>/dev/null || echo 0)"
-    if [ "${ver:-0}" -ge 310 ]; then PY="$cand"; break; fi
-  fi
-done
+# Allow explicit Python override (useful on macOS with old system Python).
+if [ -n "${SKILLOPT_SLEEP_PYTHON:-}" ]; then
+  PY="$SKILLOPT_SLEEP_PYTHON"
+else
+  for cand in python3.12 python3.11 python3.10 python3; do
+    if command -v "$cand" >/dev/null 2>&1; then
+      ver="$("$cand" -c 'import sys; print("%d%d" % sys.version_info[:2])' 2>/dev/null || echo 0)"
+      if [ "${ver:-0}" -ge 310 ]; then PY="$cand"; break; fi
+    fi
+  done
+fi
 if [ -z "$PY" ]; then
   echo "[sleep] ERROR: need Python >= 3.10 (found none)." >&2
   exit 1
diff --git a/plugins/run-sleep.sh b/plugins/run-sleep.sh
index e46e212..310d8de 100755
--- a/plugins/run-sleep.sh
+++ b/plugins/run-sleep.sh
@@ -30,12 +30,17 @@ if [ -z "${REPO_ROOT:-}" ]; then
 fi
 
 PY=""
-for cand in python3.12 python3.11 python3.10 python3; do
-  if command -v "$cand" >/dev/null 2>&1; then
-    ver="$("$cand" -c 'import sys; print("%d%d" % sys.version_info[:2])' 2>/dev/null || echo 0)"
-    if [ "${ver:-0}" -ge 310 ]; then PY="$cand"; break; fi
-  fi
-done
+# Allow explicit Python override (useful on macOS with old system Python).
+if [ -n "${SKILLOPT_SLEEP_PYTHON:-}" ]; then
+  PY="$SKILLOPT_SLEEP_PYTHON"
+else
+  for cand in python3.12 python3.11 python3.10 python3; do
+    if command -v "$cand" >/dev/null 2>&1; then
+      ver="$("$cand" -c 'import sys; print("%d%d" % sys.version_info[:2])' 2>/dev/null || echo 0)"
+      if [ "${ver:-0}" -ge 310 ]; then PY="$cand"; break; fi
+    fi
+  done
+fi
 if [ -z "$PY" ]; then
   echo "[sleep] ERROR: need Python >= 3.10 (found none)." >&2
   exit 1
diff --git a/skillopt_sleep/cycle.py b/skillopt_sleep/cycle.py
index 4678cff..e66f436 100644
--- a/skillopt_sleep/cycle.py
+++ b/skillopt_sleep/cycle.py
@@ -144,6 +144,14 @@ def run_sleep_cycle(
         _progress(cfg, f"using {len(tasks)} seeded tasks")
     else:
         since = state.last_harvest_for(project)
+        # On first run (no prior harvest), apply lookback_hours so we don't
+        # scan the entire transcript history and trigger massive LLM mining.
+        if since is None:
+            lookback_hours = cfg.get("lookback_hours", 72)
+            if lookback_hours and lookback_hours > 0:
+                import time
+                cutoff = time.time() - lookback_hours * 3600
+                since = _now_iso(cutoff)
         max_tasks = cfg.get("max_tasks_per_night", 40)
         max_sessions = cfg.get("max_sessions_per_night", 0) or max_tasks * 3
         candidate_limit = max_tasks