diff --git a/docs/web-network-captures.md b/docs/web-network-captures.md
index c00818fd2d..e1e58275bc 100644
--- a/docs/web-network-captures.md
+++ b/docs/web-network-captures.md
@@ -465,7 +465,9 @@ api-surface grouping, then keeps the groups on the primary origin, the origin
 with the most JSON-like records (`application/json`, `application/*+json`,
 `text/plain`, `text/markdown`), whose path starts with `/api/` or `/apis/` or
 whose content types are JSON-like, and the write groups answered with no body
-(a bodiless `204 DELETE`). Every other group is listed under
+(a bodiless `204 DELETE`). Empty retained response text establishes a bodiless
+write only when its encoding is understood and unredacted; an opaque or hidden
+encoding leaves the body unknown. Every other group is listed under
 `excluded` with reason `other-origin`, `ui-page-or-asset` or `non-json`, and
 retained records without a usable request line are counted in a limitation.
 
diff --git a/src/domain/analysisView/EnvironmentManifestAccumulator.ts b/src/domain/analysisView/EnvironmentManifestAccumulator.ts
index 8a9900bf29..abaaa9b879 100644
--- a/src/domain/analysisView/EnvironmentManifestAccumulator.ts
+++ b/src/domain/analysisView/EnvironmentManifestAccumulator.ts
@@ -11,6 +11,7 @@ import {
   type WebNetworkCaptureRecord,
 } from "../webNetworkCapture.js";
 import { completeWithinViewCoverage } from "./analysisViewCoverage.js";
+import { recordedResponseBodyIsEmpty } from "./recordedResponseBody.js";
 import type { UnsignedAnalysisView } from "./analysisView.js";
 import { WebNetworkProjectionAccumulator } from "./WebNetworkProjectionAccumulator.js";
 import {
@@ -105,14 +106,14 @@ const responseTextSchema = z.object({
   }),
 });
 /** Whether a record's response had no body: a 204 or 205, an empty text, or a recorded size of zero; a missing text alone may be a body not kept. */
-const emptyResponse = (reported: unknown): boolean => {
-  const parsed = responseTextSchema.safeParse(reported);
+const emptyResponse = (record: WebNetworkCaptureRecord): boolean => {
+  const parsed = responseTextSchema.safeParse(record.reported);
   if (!parsed.success) return false;
   const { status, content } = parsed.data.response;
   return (
     status === 204 ||
     status === 205 ||
-    content?.text === "" ||
+    recordedResponseBodyIsEmpty(record) ||
     ((content?.text === undefined || content.text === null) &&
       content?.size === 0)
   );
@@ -292,7 +293,7 @@ export class EnvironmentManifestAccumulator extends WebNetworkProjectionAccumula
         route,
         queryNames,
         { key, group },
-        { shape: bodyShape.value, empty: emptyResponse(record.reported) },
+        { shape: bodyShape.value, empty: emptyResponse(record) },
       );
     } finally {
       this.releaseTemporary();
diff --git a/src/domain/analysisView/EnvironmentStateAccumulator.ts b/src/domain/analysisView/EnvironmentStateAccumulator.ts
index 8c4a98cff1..4ca0f319b4 100644
--- a/src/domain/analysisView/EnvironmentStateAccumulator.ts
+++ b/src/domain/analysisView/EnvironmentStateAccumulator.ts
@@ -30,6 +30,7 @@ import {
 import {
   base64PrefixChars,
   readRecordedResponseBody,
+  recordedResponseBodyIsEmpty,
   type RecordedResponseBody,
 } from "./recordedResponseBody.js";
 import {
@@ -296,13 +297,7 @@ export class EnvironmentStateAccumulator extends EnvironmentManifestAccumulator
     const entry = this.#entries.get(ordinal);
     if (entry === undefined) return false;
     if (entry.facts.status === 204) return true;
-    // Emptiness needs only a tiny decoded prefix; never decode a whole body outside the state budget.
-    const body = readRecordedResponseBody(entry.record, 0);
-    return (
-      body.bodyText === "" &&
-      body.bodyEncoding === undefined &&
-      body.bodyCut !== true
-    );
+    return recordedResponseBodyIsEmpty(entry.record);
   }
 
   /** Project the init state of the manifest's primary origin; records keep timeline order. */
diff --git a/src/domain/analysisView/environmentManifestView.test.ts b/src/domain/analysisView/environmentManifestView.test.ts
index 4c50886596..e6b4ae661b 100644
--- a/src/domain/analysisView/environmentManifestView.test.ts
+++ b/src/domain/analysisView/environmentManifestView.test.ts
@@ -1102,6 +1102,54 @@ it("keeps a write answered with no body as a tool whatever its content type, but
   ]);
 });
 
+it("keeps opaque or redacted empty response text unknown when selecting bodiless writes", () => {
+  const capture = syntheticCapture([
+    ["POST", "https://s.test/opaque/1", "text/html"],
+    ["POST", "https://s.test/hidden/1", "text/html"],
+    ["POST", "https://s.test/base64/1", "text/html"],
+  ]);
+  for (const [index, record] of capture.records.entries()) {
+    record.reported = {
+      ...(record.reported as Record<string, unknown>),
+      response: {
+        status: 200,
+        content: {
+          mimeType: "text/html",
+          text: "",
+          ...(index === 0 ? { encoding: "opaque" } : {}),
+          ...(index === 2 ? { encoding: "base64" } : {}),
+        },
+      },
+    };
+    if (index === 1)
+      record.redactions = [
+        {
+          pointer: "/response/content",
+          reason: "explicit-sensitive-value",
+          scope: "property-name",
+        },
+      ];
+    if (index === 2)
+      record.binary_fields = [
+        {
+          pointer: "/response/content/text",
+          representation: "har-base64-content",
+          state: "retained",
+          content_base64: "",
+          bytes: 0,
+          sha256:
+            "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
+        },
+      ];
+  }
+  const projected = manifest([], capture);
+  expect(projected.tools.map(line)).toEqual(["POST /base64/{numeric}"]);
+  expect(projected.excluded.map((entry) => entry.path_template)).toEqual([
+    "/hidden/{numeric}",
+    "/opaque/{numeric}",
+  ]);
+});
+
 it("refuses a parent whose subject is absent or names another path or digest", () => {
   const parent = parentOf();
   const refusal = {
diff --git a/src/domain/analysisView/recordedResponseBody.ts b/src/domain/analysisView/recordedResponseBody.ts
index ad781ec4ca..07286d1176 100644
--- a/src/domain/analysisView/recordedResponseBody.ts
+++ b/src/domain/analysisView/recordedResponseBody.ts
@@ -70,3 +70,15 @@ export const readRecordedResponseBody = (
     return { bodyText: encoded, bodyEncoding: "base64", ...flags };
   }
 };
+
+/** Prove decoded emptiness with a bounded prefix, preserving encoding and cut uncertainty. */
+export const recordedResponseBodyIsEmpty = (
+  record: WebNetworkCaptureRecord,
+): boolean => {
+  const body = readRecordedResponseBody(record, 0);
+  return (
+    body.bodyText === "" &&
+    body.bodyEncoding === undefined &&
+    body.bodyCut !== true
+  );
+};