diff --git a/README.md b/README.md
index 8ee1bfc..f13a2aa 100644
--- a/README.md
+++ b/README.md
@@ -183,7 +183,7 @@ The build runs all nine guards before it writes anything:
 ```
 check-rules: OK — 108 rules, 34 files scanned, 3 aliases + 46 constant sets checked, 387 formulas verified
 check-kits: OK — 25 roles, 10 trades, 218 catalogue items, every kit key resolves, every posting can use what it carries, every loadout distinct
-check-lang: OK — en.json, 1016 keys, no leaf/branch collisions
+check-lang: OK — en.json, 1018 keys, no leaf/branch collisions
 check-templates: OK — 19 templates compile
 check-behaviour: OK — 76 behavioural tests
 check-scenarios: OK — 10 scenario files, 78 mechanic tags, every skill named resolves against 62 catalogue entries
diff --git a/docs/REVIEW_LOG.md b/docs/REVIEW_LOG.md
index 2f6b53a..aa9e97e 100644
--- a/docs/REVIEW_LOG.md
+++ b/docs/REVIEW_LOG.md
@@ -5363,3 +5363,35 @@ generated and validated against `npm run check`, and three sentences around it s
 "the eight guards" while nine ran. `update-readme` now rewrites the count word as well as
 the block. The comment warning that a hardcoded list goes stale was sitting four lines
 above the prose that had gone stale.
+
+## R-256 — the header said 9 while the body said 4
+
+Verifying R-255 on a live sheet showed the rule working everywhere it was built and
+contradicted in the one place a GM actually looks first. The header's ARMOUR field is the
+hide the creature HAS; grounded, the hit-location table underneath it read 4 and the
+header still read 9. Nothing computes off that field, so nothing was wrong in the code —
+it was wrong at the table, which is the only place that counts.
+
+The field stays editable and stays 9, because 9 is the creature's hide and that is what a
+GM needs to type into. Underneath it, when `system.grounded` is set, the sheet now states
+what is in play: **DOWN: 4 · CHEST 9**, from `exposedHideFor` rather than from a second
+opinion, with the reason on the tooltip.
+
+**The guard, and what it caught on the way.** check-rules forbids redefining a rule BY
+NAME, which misses how this actually goes wrong: nobody redefines `exposedHideFor`, they
+write `Math.floor(hide / 2)` in the sheet because it is one keystroke cheaper than an
+import. I wrote the wrong version first to prove the point and check-rules passed it
+happily. It now fails any file outside `rules.mjs` that halves a hide inline, with the
+file and line; the check files are exempt, because independently stating the expected
+value is what a test is for.
+
+**Open, and worse than what I fixed.** Writing that guard turned up two copies of a
+different armour rule. `armourAgainst` — critical ignores armour, special halves it —
+lives in `ringbrp.mjs:414`, not in `rules.mjs`, so the authority never covered it; and
+`tools/simulate.mjs:267` has its own inline version rather than importing it. They agree
+today, so no published number is wrong. But every figure in BESTIARY.md and the whole
+lethality baseline comes out of the simulator, so the day someone changes how a special
+hit meets armour, the game changes and the measurements do not, and the guards will all
+still pass. That is R-251 with a longer fuse. Not fixed here: moving a rule into
+`rules.mjs` and re-pointing the simulator at it is a change to the measurement pipeline
+and wants its own before-and-after.
diff --git a/lang/en.json b/lang/en.json
index a841174..e088df6 100644
--- a/lang/en.json
+++ b/lang/en.json
@@ -201,6 +201,8 @@
   "RINGBRP.Sheet.MajorWound": "Major wound",
   "RINGBRP.Sheet.MajorWoundHint": "A single blow dealing this much, after armour, causes a Major Wound.",
   "RINGBRP.Sheet.Armour": "Armour",
+  "RINGBRP.Sheet.GroundedHide": "down: {body} · chest {vital}",
+  "RINGBRP.Sheet.GroundedHideHint": "It is on the ground. Half the hide is no longer between you and it — except the chest, which faces you whatever posture it is in.",
   "RINGBRP.Sheet.DamageMod": "Damage mod",
   "RINGBRP.Sheet.MOV": "MOV",
   "RINGBRP.Sheet.DexRank": "DEX rank",
diff --git a/ringbrp.mjs b/ringbrp.mjs
index 1e8db71..70f2e3b 100644
--- a/ringbrp.mjs
+++ b/ringbrp.mjs
@@ -4713,6 +4713,18 @@ class RingBRPCharacterSheet extends ActorSheet {
     ctx.RINGBRP = RINGBRP;
     ctx.isCharacter = this.actor.type === "character";
 
+    /* R-255. The header field is the hide the beast HAS. Grounded, that is not the hide
+       that applies, and a GM reading 9 off the top of the sheet while the body reads 4
+       will use the wrong number — the same defect as a stat block that disagrees with
+       its actor, one layer in. Say what is in play, from the function the body uses. */
+    {
+      const hide = Number(sys.naturalArmour?.value) || 0;
+      const body = exposedHideFor(hide, sys.grounded, "leg");
+      ctx.groundedHide = (sys.grounded && hide && body !== hide)
+        ? { body, vital: exposedHideFor(hide, sys.grounded, "vital") }
+        : null;
+    }
+
     ctx.skillsByCategory = {};
     for (const key of Object.keys(RINGBRP.categories)) ctx.skillsByCategory[key] = [];
     for (const it of this.actor.items) {
diff --git a/styles/ringbrp.css b/styles/ringbrp.css
index 0a51b43..c053c48 100644
--- a/styles/ringbrp.css
+++ b/styles/ringbrp.css
@@ -228,6 +228,12 @@
   width: 44px; text-align: center; font-size: 24px;
   background: transparent; border: none; padding: 0; color: var(--rb-white);
 }
+.rb-grounded-hide {
+  display: block; margin-top: 2px;
+  font-family: var(--rb-body); font-size: 9px; font-weight: 700;
+  letter-spacing: .04em; text-transform: uppercase;
+  color: var(--rb-danger, #d9534f); white-space: nowrap;
+}
 .rb-wounded { border-color: var(--rb-danger) !important; }
 .rb-wound-flag {
   font-family: var(--rb-body); font-size: 10px; font-weight: 700;
diff --git a/system.json b/system.json
index 3c31e19..7770f07 100644
--- a/system.json
+++ b/system.json
@@ -2,7 +2,7 @@
   "id": "ringbrp",
   "title": "The Custodians",
   "description": "A Basic Roleplaying game of agents who cross the crossing to contain what should not be there — and who come back a little less from here each time.",
-  "version": "1.7.10",
+  "version": "1.7.11",
   "compatibility": {
     "minimum": 13,
     "verified": "14.364"
diff --git a/templates/npc-sheet.hbs b/templates/npc-sheet.hbs
index 9eb8ac2..c13c53b 100644
--- a/templates/npc-sheet.hbs
+++ b/templates/npc-sheet.hbs
@@ -13,7 +13,9 @@
         <input type="number" name="system.hp.value" value="{{sys.hp.value}}"/><span class="rb-slash">/</span><span class="rb-max">{{sys.hp.max}}</span></div>
       <div class="rb-mw"><span class="rb-vital-label">{{localize "RINGBRP.Sheet.MajorWound"}}</span><span class="rb-big">{{sys.majorWound.value}}</span></div>
       <div class="rb-armour"><span class="rb-vital-label">{{localize "RINGBRP.Sheet.Armour"}}</span>
-        <input type="number" name="system.naturalArmour.value" value="{{sys.naturalArmour.value}}"/></div>
+        <input type="number" name="system.naturalArmour.value" value="{{sys.naturalArmour.value}}"/>
+        {{#if groundedHide}}<span class="rb-grounded-hide"
+          data-tooltip="{{localize 'RINGBRP.Sheet.GroundedHideHint'}}">{{localize "RINGBRP.Sheet.GroundedHide" body=groundedHide.body vital=groundedHide.vital}}</span>{{/if}}</div>
       {{!-- The body plan. Every NPC has always HAD hit locations; nothing on this
             sheet ever let a GM choose which body they belonged to, so every bear and
             every dragon in the game was quietly a man with two arms. --}}
diff --git a/tools/check-rules.mjs b/tools/check-rules.mjs
index 9588c5e..273ee7b 100644
--- a/tools/check-rules.mjs
+++ b/tools/check-rules.mjs
@@ -42,6 +42,25 @@ for (const rel of files) {
   }
 }
 
+/* 1b. and none of them may re-derive the hide ------------------------------- *
+ * Redefinition is caught by NAME above, which misses the way this actually goes
+ * wrong: the sheet header wanted the grounded hide and `Math.floor(hide / 2)` is
+ * one keystroke cheaper than importing exposedHideFor. Then the header and the hit
+ * locations are two rules that happen to agree, until one of them is changed. The
+ * exemption is the check files, where stating the expected value independently is
+ * the entire point of a test.                                                    */
+{
+  const inlineHalving = /Math\.(?:floor|round|ceil)\(\s*[^()]*\b(?:hide|naturalArmour)\b[^()]*\/\s*2/i;
+  for (const rel of files) {
+    if (rel.startsWith("tools/check-")) continue;
+    const src = await readFile(new URL(rel, root), "utf8");
+    src.split("\n").forEach((line, i) => {
+      if (inlineHalving.test(line))
+        fail(`${rel}:${i + 1} halves natural armour inline — exposedHideFor() owns that`);
+    });
+  }
+}
+
 /* 2. aliases must be identity-equal ---------------------------------------- *
  * REQUIRED is authoritative and hand-held on purpose. Discovery alone is not
  * enough: the original bug replaced an alias with an arrow function, which a