diff --git a/docs/plans/gpu-fleet.md b/docs/plans/gpu-fleet.md
index 4dafc3476..15d469b61 100644
--- a/docs/plans/gpu-fleet.md
+++ b/docs/plans/gpu-fleet.md
@@ -42,3 +42,18 @@ nodes were igneum-build-1 (26611) and dn2-seed's one mapped port; a true mesh ne
 
 - 19:41Z: the 13 live boxes converted (supervisor started, every node synced, every prover up).
 - Owed: the Devnet 2 six after the block-rate runs; the L4 and the AMD pair when a provider reopens; the ports on re-rent.
+
+## The 10 percent rule (6 October 2026, 20:00Z, from the finality pause)
+
+What happened: the class v4 rehearsal job took the GPUs of 13 live-devnet miners between 18:27Z and 18:30Z (their
+live nodes stayed up and synced, but a voter's weight is its blue blocks, and a miner that stops mining stops being
+a voter), and with seven earlier leavers that was 42.7 percent of the frozen voter table; finality rule v3 then holds
+the pause for one full window, and the first lock after 18:39:36Z is expected at about 20:40Z. The fleet's read that
+"the boxes never left the devnet" was true of the nodes and wrong about the weight.
+
+The rule: never remove more than 10 percent of the live devnet's 30-day weight in any hour. Weight is counted by blue
+blocks per key over the window, read from the hub; any experiment that borrows live miners does it in slices with an
+hour between slices; a standing box's miner is never stopped (or its GPU shared with a second worker) by a job
+without that check. `lib/standing.py weight_check <labels>` is the gate: it reads the hub's blue blocks per payout key
+over the window, sums the share of the labels asked for, and refuses the job when the share since the last hour's
+removals exceeds 10 percent; every fleet job that touches a standing box's miner calls it first.
diff --git a/tools/fleet/lib/standing.py b/tools/fleet/lib/standing.py
index 2fa58a1b8..c8f120c3d 100644
--- a/tools/fleet/lib/standing.py
+++ b/tools/fleet/lib/standing.py
@@ -15,6 +15,9 @@ box side (the supervisor loop). Every call goes through lib.box.
                           same shape (card, VRAM, provider) with the label suffixed "-r<n>", set it up, install the
                           supervisor, mark the old row destroyed; the Devnet 2 roles take their seed from the registry
   loop(every=600)         check, then rerent what died and update what is behind, every ten minutes
+  weight_check(labels)    the 10 percent rule (20:00Z): the labels' share of the live devnet's weight (blue blocks per
+                          key over the window, from the hub) plus what was removed in the last hour must stay under
+                          10 percent, or the job is refused; every job that stops or shares a standing miner calls it
 Nothing here destroys a standing box; destroy() in lib.box stays for the one-shot boxes.
 """
 import os, sys, json, time, datetime, subprocess
@@ -86,6 +89,40 @@ def rerent(label):
         Registry.patch(str(nid), standing=True, role=b.get("role", "live"), standing_since=now(), rerents=n, rerent_of=label)
     Registry.patch(iid, state="destroyed", destroyed_at=now(), destroyed_reason="host died, re-rented as " + new)
     return new
+# ---- the 10 percent rule (20:00Z): never remove more than 10 percent of the live devnet's 30-day weight in any hour ----
+WEIGHT_LOG = os.path.join(ROOT, "weight-removals.jsonl")
+def weight_shares(window_blocks=30*86400):
+    """Blue blocks per payout label over the window, from the hub's node (igneum-miner payouts); returns {label: share}."""
+    hub = next((v for v in Registry.load().values() if v.get("hub") and v.get("state") != "destroyed"), None)
+    if not hub: raise SshError("no hub box")
+    b = Box(hub["ssh_host"], hub["ssh_port"], "hub-1", None, None, hub.get("provider"))
+    rc, out, err = b.run("/opt/igneum/pkg/bin/igneum-miner payouts grpc://127.0.0.1:26610 2>/dev/null | tail -400", 120)
+    rows = {}
+    for ln in out.splitlines():
+        parts = ln.split()
+        nums = [p for p in parts if p.isdigit()]
+        if len(parts) >= 2 and nums:
+            rows[parts[0]] = rows.get(parts[0], 0) + int(nums[-1])
+    tot = sum(rows.values()) or 1
+    return {k: v / tot for k, v in rows.items()}, out[-600:]
+def weight_check(labels, limit=0.10, hours=1.0):
+    """Refuses when the labels' weight plus what was removed in the last `hours` exceeds `limit`. Records an allowed removal."""
+    shares, raw = weight_shares()
+    reg = Registry.load(); keys = {}
+    for l in labels:
+        iid, b = Registry.find(l); keys[l] = (b.get("wallet") or "").lower()
+    want = sum(shares.get(k, 0) for k in keys.values()) + sum(shares.get(l, 0) for l in labels)
+    since = time.time() - hours * 3600; recent = 0.0
+    if os.path.exists(WEIGHT_LOG):
+        for ln in open(WEIGHT_LOG):
+            try: j = json.loads(ln)
+            except Exception: continue
+            if j.get("ts", 0) >= since: recent += float(j.get("share", 0))
+    ok = (want + recent) <= limit
+    verdict = {"labels": labels, "share": round(want, 4), "removed_last_hour": round(recent, 4), "limit": limit, "ok": ok, "t": now()}
+    if ok:
+        with open(WEIGHT_LOG, "a") as f: f.write(json.dumps({"ts": time.time(), "labels": labels, "share": want}) + "\n")
+    return verdict
 def loop(every=600):
     dead = {}
     while True:
@@ -112,3 +149,7 @@ if __name__ == "__main__":
     elif a[0] == "update": print(update(a[1]))
     elif a[0] == "rerent": print(rerent(a[1]))
     elif a[0] == "loop": loop(int(a[1]) if len(a) > 1 else 600)
+    elif a[0] == "weight_check":
+        v = weight_check(a[1:]); print(json.dumps(v)); sys.exit(0 if v["ok"] else 1)
+    elif a[0] == "weights":
+        sh, raw = weight_shares(); print(json.dumps(dict(sorted(sh.items(), key=lambda kv: -kv[1])[:40]), indent=1))