diff --git a/apps/server/src/orchestration/ActivityPayloadProjection.test.ts b/apps/server/src/orchestration/ActivityPayloadProjection.test.ts
index fc9ea4b62268..ac19f98f302b 100644
--- a/apps/server/src/orchestration/ActivityPayloadProjection.test.ts
+++ b/apps/server/src/orchestration/ActivityPayloadProjection.test.ts
@@ -115,3 +115,45 @@ describe("projectActivityPayload agent-field survival", () => {
     expect(projected.payload).toEqual(source.payload);
   });
 });
+
+describe("projectActivityPayload legacy retraction compatibility", () => {
+  function retractionFailure(detail: string): OrchestrationThreadActivity {
+    return {
+      id: "retraction-failure-1",
+      tone: "error",
+      kind: "turn.retract.failed",
+      summary: "Message retract failed",
+      payload: {
+        requestId: "request-1",
+        stage: "provider-rollback",
+        retryable: false,
+        detail,
+      },
+      turnId: "turn-1",
+      createdAt: "2026-08-12T18:49:47.397Z",
+    } as unknown as OrchestrationThreadActivity;
+  }
+
+  it("marks replayed unavailable-boundary failures silent", () => {
+    const projected = projectActivityPayload(
+      retractionFailure(
+        "Provider adapter validation failed (claudeAgent) in rollbackThreadTo: Provider history has 3 turns, below retained boundary 11.",
+      ),
+    );
+
+    expect(projected.payload).toMatchObject({
+      requestId: "request-1",
+      detail:
+        "Provider adapter validation failed (claudeAgent) in rollbackThreadTo: Provider history has 3 turns, below retained boundary 11.",
+      silent: true,
+    });
+  });
+
+  it("keeps unrelated retraction failures visible", () => {
+    const source = retractionFailure(
+      "Provider adapter validation failed (claudeAgent) in rollbackThreadTo: retainedTurnCount must be an integer >= 0.",
+    );
+
+    expect(projectActivityPayload(source)).toBe(source);
+  });
+});
diff --git a/apps/server/src/orchestration/ActivityPayloadProjection.ts b/apps/server/src/orchestration/ActivityPayloadProjection.ts
index 0c2c6620d885..558f0cfe2c64 100644
--- a/apps/server/src/orchestration/ActivityPayloadProjection.ts
+++ b/apps/server/src/orchestration/ActivityPayloadProjection.ts
@@ -18,6 +18,35 @@ function asTrimmedString(value: unknown): string | null {
   return trimmed.length > 0 ? trimmed : null;
 }
 
+const UNAVAILABLE_RETAINED_BOUNDARY_DETAIL =
+  /^Provider adapter validation failed \([^)]+\) in rollbackThreadTo: Provider history has \d+ turns, below retained boundary \d+\.$/;
+
+function normalizeLegacyRetractionFailure(
+  activity: OrchestrationThreadActivity,
+): OrchestrationThreadActivity {
+  const payload = asRecord(activity.payload);
+  if (
+    activity.kind !== "turn.retract.failed" ||
+    !payload ||
+    typeof payload.detail !== "string" ||
+    !UNAVAILABLE_RETAINED_BOUNDARY_DETAIL.test(payload.detail)
+  ) {
+    return activity;
+  }
+
+  // Boundary failures emitted before stale Esc retractions became silent are
+  // immutable event history. Normalize them at the wire boundary so every
+  // projection rebuild keeps the compatibility behavior without rewriting
+  // the event store or the persisted activity payload.
+  return {
+    ...activity,
+    payload: {
+      ...payload,
+      silent: true,
+    },
+  };
+}
+
 export const MAX_PROJECTED_TOOL_RESULT_CHARS = 50_000;
 
 const PROJECTED_TOOL_RESULT_TRUNCATION_MARKER = "…[truncated]";
@@ -326,15 +355,16 @@ function projectMcpToolCallData(data: Record<string, unknown>): Record<string, u
 export function projectActivityPayload(
   activity: OrchestrationThreadActivity,
 ): OrchestrationThreadActivity {
-  const payload = asRecord(activity.payload);
+  const normalizedActivity = normalizeLegacyRetractionFailure(activity);
+  const payload = asRecord(normalizedActivity.payload);
   const data = asRecord(payload?.data);
   if (!payload || !data) {
-    return activity;
+    return normalizedActivity;
   }
 
   if (payload.itemType === "mcp_tool_call") {
     return {
-      ...activity,
+      ...normalizedActivity,
       payload: {
         ...payload,
         data: projectMcpToolCallData(data),
@@ -370,7 +400,7 @@ export function projectActivityPayload(
   }
 
   return {
-    ...activity,
+    ...normalizedActivity,
     payload: {
       ...payload,
       data: projectedData,