queue pressure > ZERO_PRESSURE_N(4) promotes backup to active drain (claim without deferral)

app.py

@@ -73,6 +73,11 @@ TMIN = "%Y-%m-%dT%H:%MZ"
 QPREFIX = "events/queue"
 REPO = os.environ.get("CREST_FEEDBACK_REPO", "vincewin/CREST_data")
 ZERO_DELAY_S = float(os.environ.get("ZERO_DELAY_S", "420"))   # HPC first shot
+# Backup -> active drain under pressure (user directive 2026-08-14): with
+# more than this many jobs pending, skip the polite deferral and claim the
+# next unclaimed event immediately — one solver per event, so this Space
+# always works a DIFFERENT event than the HPC.
+PRESSURE_N = int(os.environ.get("ZERO_PRESSURE_N", "4"))
 STALE_S = float(os.environ.get("ZERO_STALE_S", "600"))
 HB_S = float(os.environ.get("ZERO_HB_S", "240"))
 POLL_S = float(os.environ.get("ZERO_POLL_S", "60"))
@@ -159,6 +164,14 @@ def _scan():
     ids = sorted({os.path.basename(f)[:-5] for f in qf
                   if f.endswith(".json") and not f.endswith(".failed.json")})
     now = datetime.datetime.utcnow()
+    # queue pressure: backlog > PRESSURE_N promotes this Space from deferred
+    # backup to active drain (claim immediately; claims keep events disjoint)
+    backlog = sum(1 for ev in ids if f"{QPREFIX}/{ev}.forcing.tar.gz" in qf)
+    delay = 0.0 if backlog > PRESSURE_N else ZERO_DELAY_S
+    if backlog > PRESSURE_N and W.get("pressure") != backlog:
+        W["pressure"] = backlog
+        log(f"queue pressure: {backlog} pending jobs > {PRESSURE_N} — "
+            f"claiming without deferral")
     for ev in ids:
         if f"{QPREFIX}/{ev}.forcing.tar.gz" not in qf:
             continue
@@ -172,7 +185,7 @@ def _scan():
                    ).total_seconds()
         except Exception:
             age = 0.0
-        if age < ZERO_DELAY_S:
+        if age < delay:
             continue
         w, s, e, n = spec["bbox_basin"]
         res = DEM_RES_DEG["1"]