diff --git a/src/codex/prompt-text-probe.ts b/src/codex/prompt-text-probe.ts
index 6db8d1e49e..7782b34298 100644
--- a/src/codex/prompt-text-probe.ts
+++ b/src/codex/prompt-text-probe.ts
@@ -87,6 +87,13 @@ export interface PromptTextProbe {
   detail?: string;
 }
 
+// The prompt page is URL-addressable, so multiple mounts can ask for the same
+// process-backed snapshot at once. Keep that work single-flight: callers share
+// the current read instead of each consuming another child process and output
+// buffer. The slot is cleared after either success or failure so later operator
+// visits still observe current prompt state.
+let activeProbe: Promise<PromptTextProbe> | null = null;
+
 function resolveCodexBinary(): string | null {
   const candidates = [
     join(homedir(), ".codex/packages/standalone/current/bin/codex"),
@@ -182,7 +189,7 @@ export const extractSectionsForTests = extractSections;
  * `cwd` matters: AGENTS.md and environment context are directory-dependent, so a
  * probe from the wrong place would describe a prompt the user never sees.
  */
-export async function probePromptText(timeoutMs = 15_000): Promise<PromptTextProbe> {
+async function performPromptTextProbe(timeoutMs: number): Promise<PromptTextProbe> {
   // The probe runs in CODEX_HOME, never in a caller-supplied directory. A `cwd`
   // parameter let an authenticated request read any readable folder's AGENTS.md,
   // and it also described a prompt that depends on where Codex happened to run.
@@ -236,3 +243,15 @@ export async function probePromptText(timeoutMs = 15_000): Promise<PromptTextPro
   }
   return { ok: true, codexHome, layers };
 }
+
+export async function probePromptText(timeoutMs = 15_000): Promise<PromptTextProbe> {
+  if (activeProbe) return activeProbe;
+
+  const probe = performPromptTextProbe(timeoutMs);
+  activeProbe = probe;
+  try {
+    return await probe;
+  } finally {
+    if (activeProbe === probe) activeProbe = null;
+  }
+}
diff --git a/tests/codex-prompt-route.test.ts b/tests/codex-prompt-route.test.ts
index 31f0dfd421..4a3635024c 100644
--- a/tests/codex-prompt-route.test.ts
+++ b/tests/codex-prompt-route.test.ts
@@ -799,6 +799,14 @@ describe("020 coverage completions", () => {
     // Decoding per chunk corrupts UTF-8 that straddles a chunk boundary.
     expect(probe).toContain("Buffer.concat(chunks).toString(\"utf8\")");
   });
+  test("27. concurrent prompt reads share one process-backed probe", async () => {
+    // The prompt panel is URL-addressable. Repeated mounts must not turn
+    // concurrent authenticated reads into concurrent Codex child processes.
+    const probe = await Bun.file(new URL("../src/codex/prompt-text-probe.ts", import.meta.url)).text();
+    expect(probe).toContain("let activeProbe: Promise<PromptTextProbe> | null = null;");
+    expect(probe).toContain("if (activeProbe) return activeProbe;");
+    expect(probe).toContain("if (activeProbe === probe) activeProbe = null;");
+  });
   test("24. every ownership state is named, not collapsed into a boolean", async () => {
     // developerInstructionsOwned:false covers an ABSENT key and an EXTERNAL one, and
     // a GUI that cannot tell them apart hides its own create affordance from every