diff --git a/packages/paperclip-runner/src/drivers/acpx/model-verification.test.ts b/packages/paperclip-runner/src/drivers/acpx/model-verification.test.ts
index cd4cf1317a..5fee5bc04e 100644
--- a/packages/paperclip-runner/src/drivers/acpx/model-verification.test.ts
+++ b/packages/paperclip-runner/src/drivers/acpx/model-verification.test.ts
@@ -24,7 +24,7 @@ describe("ACPX qualified model verification", () => {
     expect(setModel).not.toHaveBeenCalled();
   });
 
-  it("selects Claude's canonical model and normalizes its ACP selector", async () => {
+  it("accepts and normalizes Claude's qualified ACP selector", async () => {
     const setModel = vi.fn(async () => undefined);
     const getStatus = vi.fn(async () => ({
       models: {
@@ -33,6 +33,34 @@ describe("ACPX qualified model verification", () => {
       },
     }));
 
+    await expect(
+      requireVerifiedAcpxModel(
+        { getStatus, setModel },
+        resolveQualifiedAcpxProfile("claude", "claude-sonnet-5"),
+      ),
+    ).resolves.toMatchObject({
+      models: {
+        currentModelId: "claude-sonnet-5",
+        availableModelIds: ["default", "claude-sonnet-5", "opus"],
+      },
+    });
+    expect(setModel).not.toHaveBeenCalled();
+    expect(getStatus).toHaveBeenCalledTimes(1);
+  });
+
+  it("selects Claude's profile-pinned ACP selector from a stale default", async () => {
+    let selected = false;
+    const setModel = vi.fn(async (model: string) => {
+      expect(model).toBe("sonnet");
+      selected = true;
+    });
+    const getStatus = vi.fn(async () => ({
+      models: {
+        currentModelId: selected ? "sonnet" : "default",
+        availableModelIds: ["default", "sonnet", "opus"],
+      },
+    }));
+
     await expect(
       requireVerifiedAcpxModel(
         { getStatus, setModel },
@@ -45,7 +73,7 @@ describe("ACPX qualified model verification", () => {
       },
     });
     expect(setModel).toHaveBeenCalledTimes(1);
-    expect(setModel).toHaveBeenCalledWith("claude-sonnet-5");
+    expect(setModel).toHaveBeenCalledWith("sonnet");
     expect(getStatus).toHaveBeenCalledTimes(2);
   });
 
diff --git a/packages/paperclip-runner/src/drivers/acpx/model-verification.ts b/packages/paperclip-runner/src/drivers/acpx/model-verification.ts
index 6a875c94ac..e178dcabe1 100644
--- a/packages/paperclip-runner/src/drivers/acpx/model-verification.ts
+++ b/packages/paperclip-runner/src/drivers/acpx/model-verification.ts
@@ -28,24 +28,26 @@ export async function requireVerifiedAcpxModel(
     );
   }
   const requestedModel = profile.qualificationModel;
+  const providerModel = profile.reportedModelId;
   let status = await control.getStatus();
-  const mustSelectCanonical =
-    profile.reportedModelId !== requestedModel ||
-    status.models?.currentModelId !== requestedModel;
-  if (mustSelectCanonical) {
+  if (status.models?.currentModelId !== providerModel) {
     if (!control.setModel) {
       throw acpxModelVerificationError(
         "ACPX_MODEL_SELECTION_UNAVAILABLE",
-        "ACPX agent cannot verify its canonical model through ACP config options",
+        "ACPX agent cannot verify its qualified model through ACP config options",
       );
     }
-    await control.setModel(requestedModel);
+    // The caller-facing model is already pinned by resolveQualifiedAcpxProfile.
+    // Select the immutable ACP-facing identifier from that same profile: some
+    // providers expose a stable selector (for example Claude's `sonnet`) while
+    // Paperclip publishes the canonical model name after verification.
+    await control.setModel(providerModel);
     status = await control.getStatus();
   }
-  if (status.models?.currentModelId !== profile.reportedModelId) {
+  if (status.models?.currentModelId !== providerModel) {
     throw acpxModelVerificationError(
       "ACPX_EFFECTIVE_MODEL_MISMATCH",
-      `ACPX effective model mismatch: requested ${requestedModel}, expected ACP selector ${profile.reportedModelId}, received ${status.models?.currentModelId ?? "unverified"}`,
+      `ACPX effective model mismatch: requested ${requestedModel}, expected ACP selector ${providerModel}, received ${status.models?.currentModelId ?? "unverified"}`,
     );
   }
   return normalizeQualifiedModelStatus(status, profile);