diff --git a/open-sse/translator/response/openai-responses.ts b/open-sse/translator/response/openai-responses.ts
index 346c23ffa9..4533b30958 100644
--- a/open-sse/translator/response/openai-responses.ts
+++ b/open-sse/translator/response/openai-responses.ts
@@ -1185,10 +1185,8 @@ function openaiResponsesToOpenAIResponseStream(chunk, state) {
       !(state.reasoningItemsWithDelta instanceof Set && state.reasoningItemsWithDelta.size > 0);
     if (emittedForItem || emittedWithoutItemId) return null;
 
-    // #7095/#7176 reconciliation: computed WITHOUT mutating `item`, so an
-    // encrypted-only reasoning item (and its `encrypted_content`) is never
-    // rewritten with a fabricated `summary` — the placeholder only feeds this
-    // synthetic client-facing delta chunk.
+    // #7176/#7243: only synthesize from real upstream plaintext — never mutate
+    // `item` and never fabricate placeholder text for encrypted-only reasoning.
     const summaryText = getVisibleResponsesReasoningSummaryText(item);
     if (!summaryText) return null;
     return buildResponsesReasoningDeltaChunk(state, summaryText);
diff --git a/open-sse/translator/response/openai-responses/pureHelpers.ts b/open-sse/translator/response/openai-responses/pureHelpers.ts
index e35ad24854..01999f9ac9 100644
--- a/open-sse/translator/response/openai-responses/pureHelpers.ts
+++ b/open-sse/translator/response/openai-responses/pureHelpers.ts
@@ -177,27 +177,19 @@ export function extractResponsesReasoningSummaryText(item) {
     .join("\n\n");
 }
 
-// #7095/#7176 — when Codex exposes a reasoning item only as encrypted private
-// reasoning (no plaintext summary), chat clients would otherwise see nothing in
-// their thinking panel. Reconciles two goals that used to be in tension:
-//   - #7095 wants a visible placeholder in the chat client.
-//   - #7176 wants the upstream response item left untouched, so `encrypted_content`
-//     (needed by Codex for subsequent requests) is never overwritten by a
-//     fabricated `summary`.
-// This function computes the placeholder text WITHOUT mutating `item` — callers
-// use the returned text for synthetic client-facing events only.
-const ENCRYPTED_REASONING_PLACEHOLDER =
-  "Codex is reasoning, but the upstream Responses API exposed this reasoning block only as encrypted private reasoning. OmniRoute cannot recover the plaintext.";
-
+// #7095/#7176/#7243 — when Codex exposes a reasoning item only as encrypted
+// private reasoning (no plaintext summary), callers may synthesize client-facing
+// reasoning summary events from this helper. Reconciles three goals:
+//   - #7176: never mutate the upstream item — `encrypted_content` (needed by
+//     Codex for subsequent requests) must not be overwritten with a fabricated
+//     `summary`.
+//   - #7095: real plaintext summaries from upstream are forwarded to chat
+//     clients that render a thinking panel.
+//   - #7243: when upstream provides no plaintext summary, do NOT fabricate an
+//     alarming error-like paragraph into `reasoning_summary_text.delta` — clients
+//     would display it as if it were real reasoning. Return empty so synthetic
+//     summary events are suppressed; the reasoning item (with `encrypted_content`)
+//     still arrives on `response.output_item.done`.
 export function getVisibleResponsesReasoningSummaryText(item) {
-  const existingSummary = extractResponsesReasoningSummaryText(item);
-  if (existingSummary) return existingSummary;
-
-  const hasEncryptedReasoning =
-    item &&
-    item.type === "reasoning" &&
-    typeof item.encrypted_content === "string" &&
-    item.encrypted_content.length > 0;
-
-  return hasEncryptedReasoning ? ENCRYPTED_REASONING_PLACEHOLDER : "";
+  return extractResponsesReasoningSummaryText(item);
 }
diff --git a/open-sse/utils/stream.ts b/open-sse/utils/stream.ts
index 45b0d92c0c..c2f81e035c 100644
--- a/open-sse/utils/stream.ts
+++ b/open-sse/utils/stream.ts
@@ -1047,9 +1047,9 @@ export function createSSEStream(options: StreamOptions = {}) {
       return;
     }
 
-    // #7095/#7176 reconciliation: compute the visible placeholder WITHOUT
-    // mutating `item` — the encrypted reasoning item (and its `encrypted_content`,
-    // required by Codex for subsequent requests) is forwarded to the client intact.
+    // #7176/#7243: only synthesize summary events from real upstream plaintext —
+    // never mutate `item` and never fabricate alarming placeholder text for
+    // encrypted-only reasoning (`encrypted_content` still forwards intact).
     const visibleSummary = getVisibleResponsesReasoningSummaryText(item);
 
     if (!visibleSummary) {
diff --git a/tests/integration/codex-chat-reasoning-http-e2e.test.ts b/tests/integration/codex-chat-reasoning-http-e2e.test.ts
index 44363fd8fc..051b5ba235 100644
--- a/tests/integration/codex-chat-reasoning-http-e2e.test.ts
+++ b/tests/integration/codex-chat-reasoning-http-e2e.test.ts
@@ -285,14 +285,16 @@ test("chat completions streams Codex Responses reasoning through real route HTTP
     const chunks = parseSse(raw);
     assert.equal(chunks.at(-1), "[DONE]");
     const payloads = chunks.slice(0, -1).map((chunk) => JSON.parse(chunk));
+    // #7243: encrypted-only reasoning must not fabricate client-visible
+    // reasoning_content (old #7095/#7304 placeholder is gone).
     const reasoningContentDeltas = payloads
       .map((payload) => payload.choices?.[0]?.delta?.reasoning_content)
       .filter((content): content is string => Boolean(content));
-    assert.equal(reasoningContentDeltas.length, 1);
+    assert.equal(reasoningContentDeltas.length, 0);
     const reasoningContent = reasoningContentDeltas.join("");
-    assert.match(reasoningContent, /encrypted (?:state|private reasoning)/i);
+    assert.doesNotMatch(reasoningContent, /encrypted (?:state|private reasoning)/i);
+    assert.doesNotMatch(raw, /OmniRoute cannot recover|Codex is reasoning/i);
     assert(!raw.includes(ENCRYPTED_CONTENT_SENTINEL), raw);
-    assert(!reasoningContent.includes(ENCRYPTED_CONTENT_SENTINEL), reasoningContent);
     assert(
       payloads.some((payload) => payload.choices?.[0]?.delta?.content === "The answer is 42.")
     );
diff --git a/tests/unit/encrypted-reasoning-summary-7243.test.ts b/tests/unit/encrypted-reasoning-summary-7243.test.ts
new file mode 100644
index 0000000000..12f918adaf
--- /dev/null
+++ b/tests/unit/encrypted-reasoning-summary-7243.test.ts
@@ -0,0 +1,35 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+
+const { getVisibleResponsesReasoningSummaryText } = await import(
+  "../../open-sse/translator/response/openai-responses/pureHelpers.ts"
+);
+
+test("#7243 getVisibleResponsesReasoningSummaryText returns upstream plaintext summary", () => {
+  const item = {
+    type: "reasoning",
+    summary: [{ type: "summary_text", text: "Planning the next edit." }],
+    encrypted_content: "opaque-blob",
+  };
+
+  assert.equal(getVisibleResponsesReasoningSummaryText(item), "Planning the next edit.");
+});
+
+test("#7243 getVisibleResponsesReasoningSummaryText suppresses synthetic text for encrypted-only reasoning", () => {
+  const item = {
+    type: "reasoning",
+    encrypted_content: "opaque-blob",
+  };
+
+  assert.equal(getVisibleResponsesReasoningSummaryText(item), "");
+  assert.doesNotMatch(
+    getVisibleResponsesReasoningSummaryText(item),
+    /OmniRoute cannot recover|encrypted private reasoning/i
+  );
+});
+
+test("#7243 getVisibleResponsesReasoningSummaryText returns empty for non-reasoning or empty summary", () => {
+  assert.equal(getVisibleResponsesReasoningSummaryText(null), "");
+  assert.equal(getVisibleResponsesReasoningSummaryText({ type: "message" }), "");
+  assert.equal(getVisibleResponsesReasoningSummaryText({ type: "reasoning", summary: [] }), "");
+});
diff --git a/tests/unit/stream-utilities.test.ts b/tests/unit/stream-utilities.test.ts
index 52d6d58b64..ba344fe6f2 100644
--- a/tests/unit/stream-utilities.test.ts
+++ b/tests/unit/stream-utilities.test.ts
@@ -230,16 +230,11 @@ test("createPassthroughStreamWithLogger synthesizes reasoning summary events fro
   assert.match(result, /event: response\.output_item\.done/);
 });
 
-// Reconciles #7095 (xz-dev — chat clients never saw ANY signal that Codex was
-// reasoning when the upstream Responses API exposed only encrypted private
-// reasoning) with #7176 (JxnLexn — mutating `item.summary` with a fabricated
-// placeholder corrupted the response item forwarded downstream, discarding the
-// `encrypted_content` shape Codex needs for follow-up requests). Both goals are
-// satisfied simultaneously: the client-facing synthetic delta/part events still
-// carry the placeholder text, but the forwarded `response.output_item.done`
-// payload is untouched — `encrypted_content` survives and no `summary` is
-// fabricated onto the wire item.
-test("createPassthroughStreamWithLogger shows a placeholder for encrypted reasoning items without mutating the forwarded item", async () => {
+// #7176/#7243 — encrypted-only reasoning must not mutate the forwarded item and
+// must not fabricate alarming placeholder text into client-visible reasoning
+// summary streams. The reasoning item (with `encrypted_content`) still reaches
+// the client on `response.output_item.done` for continuation.
+test("createPassthroughStreamWithLogger suppresses synthetic summary for encrypted-only reasoning without mutating the forwarded item", async () => {
   const transform = createPassthroughStreamWithLogger(
     "codex",
     null,
@@ -275,9 +270,9 @@ test("createPassthroughStreamWithLogger shows a placeholder for encrypted reason
     result += decoder.decode(value);
   }
 
-  // #7095: chat clients still see the placeholder via the synthetic events.
-  assert.match(result, /event: response\.reasoning_summary_text\.delta/);
-  assert.match(result, /Codex is reasoning/);
+  // #7243: no fabricated reasoning summary deltas when upstream has no plaintext.
+  assert.doesNotMatch(result, /event: response\.reasoning_summary_text\.delta/);
+  assert.doesNotMatch(result, /Codex is reasoning/);
 
   // #7176: the forwarded response.output_item.done payload is untouched —
   // encrypted_content survives intact and no fabricated `summary` is present.
@@ -332,9 +327,9 @@ test("createPassthroughStreamWithLogger backfills completed output with encrypte
     result += decoder.decode(value);
   }
 
-  // The placeholder still reached the client (#7095).
-  assert.match(result, /event: response\.reasoning_summary_text\.delta/);
-  assert.match(result, /Codex is reasoning/);
+  // #7243: no fabricated reasoning summary deltas when upstream has no plaintext.
+  assert.doesNotMatch(result, /event: response\.reasoning_summary_text\.delta/);
+  assert.doesNotMatch(result, /Codex is reasoning/);
 
   // The item re-serialized into the completed snapshot carries the original
   // encrypted_content and never a fabricated summary (#7176).