diff --git a/src/browser/history/QlogCapture.test.ts b/src/browser/history/QlogCapture.test.ts
index 97572d671b..bb2a7f00e6 100644
--- a/src/browser/history/QlogCapture.test.ts
+++ b/src/browser/history/QlogCapture.test.ts
@@ -332,6 +332,23 @@ it.each([
   },
 );
 
+it("counts hidden payloads only for events interpreted as transport facts", () => {
+  const text = capture([
+    { name: "extension:custom", time: 0, data: { body: "ordinary" } },
+    event([frame(0, 10, false)]),
+    { name: "recovery:packet_lost", time: 2, data: { packet_number: 5 } },
+  ]);
+  const control = facts(text);
+  expect(control.traces[0]?.incomplete_fact_records).toEqual([]);
+  const hidden = facts(text, ["data"]);
+  expect(hidden.traces[0]?.incomplete_fact_records).toEqual([1, 2]);
+  expect(hidden.decoded.records.map((record) => record.reported)).toEqual([
+    { name: "extension:custom", time: 0 },
+    { name: "transport:packet_sent", time: 1791819895000.25 },
+    { name: "recovery:packet_lost", time: 2 },
+  ]);
+});
+
 it("omits a hidden derived total for a stream with more contributions than call arguments allow", () => {
   const events = Array.from({ length: 130 }, (_, index) =>
     event(
diff --git a/src/browser/history/QlogCapture.ts b/src/browser/history/QlogCapture.ts
index b66b728fb3..61a22d9ee7 100644
--- a/src/browser/history/QlogCapture.ts
+++ b/src/browser/history/QlogCapture.ts
@@ -228,6 +228,9 @@ const collectTransportFacts = (
   },
 ): void => {
   const { fact, streams, excluded, name } = state;
+  // Unknown event payloads carry no facts under this interpretation profile.
+  // Their omission cannot make the transport-fact inventory incomplete.
+  if (name !== "recovery:packet_lost" && !packetEvent(name)) return;
   if (!object(projection.reported) || !object(projection.reported.data)) {
     fact.incomplete_fact_records.push(ordinal);
     return;
@@ -235,10 +238,7 @@ const collectTransportFacts = (
   const visible = projection.reported;
   // Facts are selected by event name, so a declaration that hides the name
   // of a loss or packet event omits its facts like any other hidden field.
-  if (
-    (name === "recovery:packet_lost" || packetEvent(name)) &&
-    visible.name !== name
-  ) {
+  if (visible.name !== name) {
     fact.incomplete_fact_records.push(ordinal);
     return;
   }
diff --git a/tests/acceptance/tools/qlogCapture.test.ts b/tests/acceptance/tools/qlogCapture.test.ts
index 3691c685dc..6c5a8bb0d1 100644
--- a/tests/acceptance/tools/qlogCapture.test.ts
+++ b/tests/acceptance/tools/qlogCapture.test.ts
@@ -45,6 +45,54 @@ const qlog = (events: unknown[]) =>
     ],
   });
 
+it("does not classify hidden custom event data as incomplete transport facts", async () => {
+  const root = await createTestTempDirectory("rea-qlog-hidden-extension-");
+  const path = join(root, "input.qlog");
+  await writeFile(
+    path,
+    qlog([
+      { name: "extension:custom", time: 1, data: { body: "ordinary" } },
+      {
+        ...event,
+        data: {
+          ...event.data,
+          frames: [{ ...event.data.frames[0], fin: false }],
+        },
+      },
+    ]),
+  );
+  const { call } = await connectLocalToolsMcp();
+  for (const sensitive of [[], ["data"]]) {
+    const response = await call("inspect_web_network_capture", {
+      capture_path: path,
+      format: "qlog",
+      sensitive_values: sensitive,
+    });
+    expect(response.isError, JSON.stringify(response)).not.toBe(true);
+    const mcp = parseEvidence(response.structuredContent);
+    const cliResult = await execute(process.execPath, [
+      cli,
+      "inspect-web-network-capture",
+      path,
+      "qlog",
+      ...sensitive.flatMap((value) => ["--sensitive-value", value]),
+      "--json",
+    ]);
+    const cliEvidence = parseEvidence(JSON.parse(cliResult.stdout));
+    expect(cliEvidence.normalized_result).toEqual(mcp.normalized_result);
+    const capture = webNetworkCaptureSchema.parse(mcp.normalized_result);
+    if (capture.format !== "qlog") throw new Error("qlog format required");
+    expect(capture.qlog.traces[0]?.incomplete_fact_records).toEqual(
+      sensitive.length === 0 ? [] : [1],
+    );
+    if (sensitive.length > 0)
+      expect(capture.records[0]?.reported).toEqual({
+        name: "extension:custom",
+        time: 1,
+      });
+  }
+});
+
 const assertAdditionalQlogFacets = async (
   call: Awaited<ReturnType<typeof connectLocalToolsMcp>>["call"],
   retained: { kind: string; evidence_id: string },