diff --git a/engine/v5/run-v5.mjs b/engine/v5/run-v5.mjs
index d41141de..f7a44472 100755
--- a/engine/v5/run-v5.mjs
+++ b/engine/v5/run-v5.mjs
@@ -30,6 +30,7 @@ import {
   evaluateEnforcement,
   PLAN_STATES,
 } from "./dispatch-plan.mjs";
+import { compareDispatchPlanToTopology } from "./plan-diff.mjs";
 import {
   classifyTopologyParticipation,
   DISPATCH_OBSERVABILITY,
@@ -217,7 +218,27 @@ async function main() {
     dispatch_plan: dispatchPlan.dispatches,
     dispatch_plan_error: dispatchPlan.error,
   });
-  writeMeta(matchId, { dispatchPlan });
+  // B's dependent variable is the deviation between the voluntary plan and the
+  // declared topology. plan-diff.mjs computed it, nothing ever called it, and
+  // nothing wrote it down — the same shape as biasReport, which judge() produced
+  // and the manifest dropped. An E2 calibration cell came back with the plan
+  // recorded and the comparison absent, which is a run that measures A and
+  // silently collects nothing for B.
+  let planDiff;
+  try {
+    const topo = JSON.parse(fs.readFileSync(path.join(regimeDir, "topology.json"), "utf8"));
+    planDiff = compareDispatchPlanToTopology(dispatchPlan, topo);
+  } catch (err) {
+    // A regime without topology.json cannot be compared; say so rather than
+    // omitting the field, so an absent comparison is distinguishable from one
+    // that was never attempted.
+    planDiff = {
+      plan_status: dispatchPlan.status,
+      comparison_available: false,
+      reason: `topology unavailable: ${err.message}`,
+    };
+  }
+  writeMeta(matchId, { dispatchPlan, planDiff });
 
   const enforcementSetup = enforceDispatch
     ? loadRequiredOffices(regimeDir)
diff --git a/engine/v5/tournament.mjs b/engine/v5/tournament.mjs
index e420fadc..f091e4e1 100644
--- a/engine/v5/tournament.mjs
+++ b/engine/v5/tournament.mjs
@@ -458,6 +458,7 @@ export async function runTournament({
     } catch {
       /* child may have failed before creating meta.json */
     }
+    result.planDiff = meta.planDiff ?? null;
     result.dispatchPlan = meta.dispatchPlan ?? {
       status: "parse_failed",
       dispatches: null,
@@ -479,6 +480,7 @@ export async function runTournament({
       result.dispatchEnforcement.status === "enforcement_passed";
     writeMeta(result.matchId, {
       dispatchPlan: result.dispatchPlan,
+      ...(result.planDiff ? { planDiff: result.planDiff } : {}),
       dispatchEnforcement: result.dispatchEnforcement,
       topologyParticipation: result.topologyParticipation,
     });
diff --git a/test/r11-instrumentation.test.mjs b/test/r11-instrumentation.test.mjs
index c9dc6c4a..a528a0dd 100644
--- a/test/r11-instrumentation.test.mjs
+++ b/test/r11-instrumentation.test.mjs
@@ -481,3 +481,37 @@ test("R11 plan events remain observable but cannot contaminate judge or skill tr
   const runtime = reconstructRuntimeGraph([plan, execution]);
   assert.equal(runtime.observed.dispatch_sequence.length, 0);
 });
+
+// ── B's dependent variable has to be written down, not merely computable ─────
+//
+// plan-diff.mjs was built with two exported functions and zero callers: the
+// comparison between the voluntary plan and the declared topology was never
+// computed and never persisted. An E2 calibration cell came back with
+// dispatchPlan recorded for all ten arms and planDiff absent from every one —
+// a run that measures A and silently collects nothing for B. This is the same
+// shape as biasReport, which judge() computed and the manifest dropped.
+test("R11 run-v5 persists the plan-vs-topology comparison next to the plan", async () => {
+  const home = fs.mkdtempSync(path.join(os.tmpdir(), "civagent-r11-plandiff-"));
+  const fake = makeFakeEnvironment(home);
+  const matchId = "r11-plandiff";
+  try {
+    const result = await spawnCollect(process.execPath, [
+      path.join(ROOT, "engine/v5/run-v5.mjs"),
+      "--backend", "native", "--no-skill", "china/tang", "test task",
+    ], { ...fake.env, CIVAGENT_MATCH_ID: matchId });
+    assert.equal(result.code, 0, result.stderr);
+
+    const meta = JSON.parse(
+      fs.readFileSync(path.join(home, ".civagent", "matches", matchId, "meta.json"), "utf8"),
+    );
+    assert.ok(meta.dispatchPlan, "precondition: the plan is recorded");
+    assert.ok(meta.planDiff, "the comparison must be recorded too, not left computable");
+    assert.equal(meta.planDiff.plan_status, meta.dispatchPlan.status,
+      "the comparison must describe the plan actually recorded");
+    assert.ok(meta.planDiff.unsupported_dimensions,
+      "and must keep naming what it cannot compare, rather than implying full coverage");
+  } finally {
+    fs.rmSync(fake.bin, { recursive: true, force: true });
+    fs.rmSync(home, { recursive: true, force: true });
+  }
+});