diff --git a/packages/chess/src/presets/capture-to-win.ts b/packages/chess/src/presets/capture-to-win.ts
index 33be00e..b811ee8 100644
--- a/packages/chess/src/presets/capture-to-win.ts
+++ b/packages/chess/src/presets/capture-to-win.ts
@@ -38,7 +38,15 @@ PRESET_REGISTRY.register({
   name: "First Blood",
   description:
     "The first player to capture any enemy piece wins the game immediately. Makes every piece precious.",
-  incompatibleWith: ["last-piece-standing"],
+  incompatibleWith: [
+    "last-piece-standing",
+    // Reciprocal: these presets redefine the terminal-state logic
+    // and are declared incompatible with us from their own files.
+    "first-promotion-wins",
+    "capture-all",
+    "suicide-chess",
+    "extinction-chess",
+  ],
   requires: [],
 
   onBeforeCapture({ engine, attacker }) {
diff --git a/packages/chess/src/presets/double-pawn-sprint.ts b/packages/chess/src/presets/double-pawn-sprint.ts
index 88aa078..8ac3829 100644
--- a/packages/chess/src/presets/double-pawn-sprint.ts
+++ b/packages/chess/src/presets/double-pawn-sprint.ts
@@ -58,7 +58,12 @@ PRESET_REGISTRY.register({
   name: "Perpetual Sprint",
   description:
     "Pawns may advance 2 squares straight forward from ANY rank (not only the home rank).",
-  incompatibleWith: [],
+  incompatibleWith: [
+    // Reciprocal: berolina-pawns redefines pawn movement and
+    // conflicts with additive pawn rules.
+    "berolina-pawns",
+    "berolina-pawns-2",
+  ],
   requires: [],
   getExtraMoves: getDoubleSprintMove,
 });
diff --git a/packages/chess/src/presets/extinction-chess.ts b/packages/chess/src/presets/extinction-chess.ts
index 5874223..ed70f4e 100644
--- a/packages/chess/src/presets/extinction-chess.ts
+++ b/packages/chess/src/presets/extinction-chess.ts
@@ -152,6 +152,10 @@ PRESET_REGISTRY.register({
     "suicide-chess",
     "capture-all",
     "first-promotion-wins",
+    // Reciprocal: every terminal-state preset blocks composition
+    // with us.
+    "capture-to-win",
+    "last-piece-standing",
   ],
   requires: [],
 
diff --git a/packages/chess/src/presets/knightmate-rules.ts b/packages/chess/src/presets/knightmate-rules.ts
index a4e1574..4dbead6 100644
--- a/packages/chess/src/presets/knightmate-rules.ts
+++ b/packages/chess/src/presets/knightmate-rules.ts
@@ -50,7 +50,15 @@ PRESET_REGISTRY.register({
   name: "Knightmate",
   description:
     "Knights are royal instead of kings. Mate the last knight to win; kings are regular pieces.",
-  incompatibleWith: ["coregal", "dual-king", "weak-dual-king"],
+  incompatibleWith: [
+    "coregal",
+    "dual-king",
+    "weak-dual-king",
+    // Reciprocal: these presets empty the royal set entirely and
+    // so conflict with any preset that declares non-king royalty.
+    "suicide-chess",
+    "capture-all",
+  ],
   requires: [],
 
   getRoyalPieces({ engine, color }): readonly EntityId[] {
diff --git a/packages/chess/src/presets/last-piece-standing.ts b/packages/chess/src/presets/last-piece-standing.ts
index eda62de..2a58b43 100644
--- a/packages/chess/src/presets/last-piece-standing.ts
+++ b/packages/chess/src/presets/last-piece-standing.ts
@@ -33,7 +33,15 @@ PRESET_REGISTRY.register({
   name: "Annihilation",
   description:
     "Checkmate is disabled. The player who captures ALL enemy pieces (king included) wins. Every capture counts.",
-  incompatibleWith: ["capture-to-win"],
+  incompatibleWith: [
+    "capture-to-win",
+    // Reciprocal: these terminal-state presets declare incompat
+    // with us from their own files.
+    "first-promotion-wins",
+    "capture-all",
+    "suicide-chess",
+    "extinction-chess",
+  ],
   requires: [],
 
   onCheckGameResult({ engine }): GameResult | undefined {
diff --git a/packages/chess/src/presets/pawn-diagonal-no-capture.ts b/packages/chess/src/presets/pawn-diagonal-no-capture.ts
index 44d8993..9217553 100644
--- a/packages/chess/src/presets/pawn-diagonal-no-capture.ts
+++ b/packages/chess/src/presets/pawn-diagonal-no-capture.ts
@@ -44,7 +44,12 @@ PRESET_REGISTRY.register({
   name: "Slanting Pawns",
   description:
     "Pawns may move one square diagonally forward to an empty square without capturing.",
-  incompatibleWith: [],
+  incompatibleWith: [
+    // Reciprocal: the berolina-pawns presets wholly redefine pawn
+    // movement and conflict with any additive pawn-movement rule.
+    "berolina-pawns",
+    "berolina-pawns-2",
+  ],
   requires: [],
   getExtraMoves: getDiagonalQuietMoves,
 });
diff --git a/packages/chess/src/presets/pawns-move-backward.ts b/packages/chess/src/presets/pawns-move-backward.ts
index e2c1a2d..1f12999 100644
--- a/packages/chess/src/presets/pawns-move-backward.ts
+++ b/packages/chess/src/presets/pawns-move-backward.ts
@@ -44,7 +44,12 @@ PRESET_REGISTRY.register({
   name: "Backward-Marching Pawns",
   description:
     "Pawns may also move 1 square straight backward to an empty square (no capture).",
-  incompatibleWith: [],
+  incompatibleWith: [
+    // Reciprocal: berolina-pawns redefines pawn movement and
+    // conflicts with additive pawn rules.
+    "berolina-pawns",
+    "berolina-pawns-2",
+  ],
   requires: [],
   getExtraMoves: getPawnBackwardMove,
 });
diff --git a/packages/chess/src/presets/presets.test.ts b/packages/chess/src/presets/presets.test.ts
index 1c1d8f9..ee8345e 100644
--- a/packages/chess/src/presets/presets.test.ts
+++ b/packages/chess/src/presets/presets.test.ts
@@ -107,6 +107,70 @@ describe("Incompatibility declarations", () => {
     expect(a.incompatibleWith).not.toContain("explosive-rook");
     expect(b.incompatibleWith).not.toContain("piece-hp");
   });
+
+  // ─────────────────────────────────────────────────────────────────
+  // Global audit (Phase F.1 of the rule-variants epic)
+  //
+  // Every preset's `incompatibleWith` entry must be SYMMETRIC: if A
+  // declares B incompatible, B must declare A incompatible too.
+  // Asymmetric declarations are bugs — the activation validator only
+  // fires when EITHER side declares the other, so a one-way
+  // declaration works by accident, but a later refactor that
+  // re-registers A without the line silently breaks the guarantee.
+  //
+  // Every entry must also reference a REAL preset id. Dangling
+  // references (typo'd ids, deleted presets) are caught here before
+  // they cause runtime `UNKNOWN_PRESET` errors.
+  // ─────────────────────────────────────────────────────────────────
+
+  it("incompatibleWith is symmetric across every registered preset", () => {
+    const all = PRESET_REGISTRY.getAll();
+    const byId = new Map(all.map(p => [p.id, p] as const));
+    const asymmetric: string[] = [];
+
+    for (const a of all) {
+      for (const bId of a.incompatibleWith) {
+        const b = byId.get(bId);
+        if (b === undefined) continue; // dangling refs caught separately
+        if (!b.incompatibleWith.includes(a.id)) {
+          asymmetric.push(
+            `"${a.id}" declares "${bId}" incompatible but "${bId}" does NOT reciprocate`,
+          );
+        }
+      }
+    }
+
+    expect(asymmetric).toEqual([]);
+  });
+
+  it("every incompatibleWith entry references a registered preset id", () => {
+    const all = PRESET_REGISTRY.getAll();
+    const ids = new Set(all.map(p => p.id));
+    const dangling: string[] = [];
+
+    for (const preset of all) {
+      for (const ref of preset.incompatibleWith) {
+        if (!ids.has(ref)) {
+          dangling.push(`"${preset.id}" → "${ref}" (unknown)`);
+        }
+      }
+    }
+
+    expect(dangling).toEqual([]);
+  });
+
+  it("no preset declares itself incompatible", () => {
+    const all = PRESET_REGISTRY.getAll();
+    const selfRefs: string[] = [];
+
+    for (const preset of all) {
+      if (preset.incompatibleWith.includes(preset.id)) {
+        selfRefs.push(preset.id);
+      }
+    }
+
+    expect(selfRefs).toEqual([]);
+  });
 });
 
 describe("Requires declarations", () => {
diff --git a/packages/chess/src/presets/wrap-board.ts b/packages/chess/src/presets/wrap-board.ts
index 4b811c4..ca355d1 100644
--- a/packages/chess/src/presets/wrap-board.ts
+++ b/packages/chess/src/presets/wrap-board.ts
@@ -206,7 +206,14 @@ PRESET_REGISTRY.register({
   name: "Cylindrical Board",
   description:
     "The board wraps horizontally: every piece (knights, kings, bishops, queens, rooks, and pawn captures) can move off one side and appear on the other.",
-  incompatibleWith: ["rook-warp"],
+  incompatibleWith: [
+    "rook-warp",
+    // Reciprocal: bouncing-pieces presets declare incompat with
+    // wrap-board because their diagonal reflection geometry is
+    // undefined on a wrapping (cylindrical) board.
+    "bouncing-pieces",
+    "bouncing-pieces-2",
+  ],
   requires: [],
   getExtraMoves: (engine, pieceId) => {
     const facts = engine.session.allFacts();