diff --git a/src/core/stream.ts b/src/core/stream.ts
index 0a84800..0195cb0 100644
--- a/src/core/stream.ts
+++ b/src/core/stream.ts
@@ -368,13 +368,24 @@ function numOrUndef(v: unknown): number | undefined {
 function strOrUndef(v: unknown): string | undefined {
   return v == null ? undefined : String(v);
 }
+
+const LEGACY_PUBLIC_STREAM_ERRORS = new Set([
+  "The media studio agent hit an error.",
+  "generation registry did not reach a terminal state",
+]);
+
 function streamErrorMessage(obj: Record<string, unknown>): string {
-  // Some server paths send `error` instead of `msg`. Keep the internal `reason`
-  // field out of user-facing frames, even when all message fields are blank.
-  for (const key of ["msg", "message", "error"]) {
+  // Only msg/message are a public message contract. Legacy media frames use
+  // fixed public `error` strings, but other `error` values may be provider
+  // exception text. Never map the internal `reason` field into a frame.
+  for (const key of ["msg", "message"]) {
     const value = obj[key];
     if (typeof value === "string" && value.trim()) return value;
   }
+  const legacyError = obj["error"];
+  if (typeof legacyError === "string" && LEGACY_PUBLIC_STREAM_ERRORS.has(legacyError)) {
+    return legacyError;
+  }
   return "";
 }
 function parseStrArray(v: unknown): string[] | undefined {
diff --git a/test/stream.test.ts b/test/stream.test.ts
index 2ef85b1..9cd6a96 100644
--- a/test/stream.test.ts
+++ b/test/stream.test.ts
@@ -31,16 +31,25 @@ test("normalizeFrame error uses contract keys msg/error_code/ref_id", () => {
   assert.deepEqual(f, { type: "error", msg: "boom", errorCode: "E42", refId: "r1" });
 });
 
-test("normalizeFrame takes the first nonblank error text and never exposes reason", () => {
+test("normalizeFrame accepts canonical and fixed legacy public error text only", () => {
   const base = { type: "error", reason: "internal detail" };
-  assert.deepEqual(normalizeFrame({ ...base, msg: "primary", error: "fallback" }), {
+  assert.deepEqual(normalizeFrame({ ...base, msg: "primary", error: "private provider exception" }), {
     type: "error", msg: "primary", errorCode: undefined, refId: undefined,
   });
-  assert.deepEqual(normalizeFrame({ ...base, msg: "  ", message: "alternate", error: "fallback" }), {
+  assert.deepEqual(normalizeFrame({ ...base, msg: "  ", message: "alternate", error: "private provider exception" }), {
     type: "error", msg: "alternate", errorCode: undefined, refId: undefined,
   });
-  assert.deepEqual(normalizeFrame({ ...base, msg: "", error: "server failure" }), {
-    type: "error", msg: "server failure", errorCode: undefined, refId: undefined,
+  assert.deepEqual(normalizeFrame({ ...base, msg: "", error: "The media studio agent hit an error." }), {
+    type: "error", msg: "The media studio agent hit an error.", errorCode: undefined, refId: undefined,
+  });
+  assert.deepEqual(normalizeFrame({ ...base, error: "generation registry did not reach a terminal state" }), {
+    type: "error", msg: "generation registry did not reach a terminal state", errorCode: undefined, refId: undefined,
+  });
+  assert.deepEqual(normalizeFrame({ ...base, error: "private provider exception: token=SECRET" }), {
+    type: "error", msg: "", errorCode: undefined, refId: undefined,
+  });
+  assert.deepEqual(normalizeFrame({ ...base, error: "The media studio agent hit an error. " }), {
+    type: "error", msg: "", errorCode: undefined, refId: undefined,
   });
   assert.deepEqual(normalizeFrame({ ...base, error: { secret: true } }), {
     type: "error", msg: "", errorCode: undefined, refId: undefined,
diff --git a/test/turn_lifecycle.test.ts b/test/turn_lifecycle.test.ts
index cc467f4..ac7aab5 100644
--- a/test/turn_lifecycle.test.ts
+++ b/test/turn_lifecycle.test.ts
@@ -224,14 +224,14 @@ test("streamed 402 after a partial delta preserves text and adds actionable sani
   }
 });
 
-test("one-shot error-key frame is a visible failed turn without exposing reason or trailing done", async () => {
+test("one-shot fixed legacy media error is visible without exposing reason or trailing done", async () => {
   resetRegistry();
   const realFetch = globalThis.fetch;
   let calls = 0;
   globalThis.fetch = (async () => {
     calls += 1;
     return sseResponse([
-      { type: "error", error: "The worker hit an error.\u001b]52;c;payload\u0007", reason: "internal detail" },
+      { type: "error", error: "The media studio agent hit an error.", reason: "internal detail" },
       { type: "done", uvt: 0, cents: 0 },
     ]);
   }) as typeof globalThis.fetch;
@@ -239,14 +239,32 @@ test("one-shot error-key frame is a visible failed turn without exposing reason
     const result = await captureWrites(() => cmdChat(cloudContext(), "ship this"));
     assert.equal(result.value, 1);
     assert.equal(calls, 1, "a terminal error must not retry or switch transports");
-    assert.match(result.stderr, /The worker hit an error\./);
-    assert.doesNotMatch(result.stderr, /internal detail|\u001b\]52|0 UVT/i);
+    assert.match(result.stderr, /The media studio agent hit an error\./);
+    assert.doesNotMatch(result.stderr, /internal detail|0 UVT/i);
     assert.equal(result.stdout, "", "an error must not fabricate model output");
   } finally {
     globalThis.fetch = realFetch;
   }
 });
 
+test("one-shot arbitrary error-key text is hidden while the turn still fails", async () => {
+  resetRegistry();
+  const realFetch = globalThis.fetch;
+  globalThis.fetch = (async () => sseResponse([
+    { type: "error", error: "provider token=SECRET\u001b]52;c;payload\u0007", reason: "internal detail" },
+    { type: "done", uvt: 0, cents: 0 },
+  ])) as typeof globalThis.fetch;
+  try {
+    const result = await captureWrites(() => cmdChat(cloudContext(), "ship this"));
+    assert.equal(result.value, 1);
+    assert.match(result.stderr, /turn failed/i);
+    assert.doesNotMatch(result.stderr, /SECRET|internal detail|\u001b\]52|0 UVT/i);
+    assert.equal(result.stdout, "");
+  } finally {
+    globalThis.fetch = realFetch;
+  }
+});
+
 test("one-shot blank error frame remains a failed turn with a fallback message", async () => {
   resetRegistry();
   const realFetch = globalThis.fetch;