diff --git a/packages/paperclip-runner/src/drivers/acpx/model-verification.test.ts b/packages/paperclip-runner/src/drivers/acpx/model-verification.test.ts
new file mode 100644
index 00000000000..cd4cf1317a4
--- /dev/null
+++ b/packages/paperclip-runner/src/drivers/acpx/model-verification.test.ts
@@ -0,0 +1,108 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { resolveQualifiedAcpxProfile } from "./qualified-profiles.js";
+import { requireVerifiedAcpxModel } from "./model-verification.js";
+
+describe("ACPX qualified model verification", () => {
+  it("accepts an exact model already reported by the provider", async () => {
+    const getStatus = vi.fn(async () => ({
+      models: {
+        currentModelId: "gpt-5.6-sol",
+        availableModelIds: ["gpt-5.6-sol"],
+      },
+    }));
+    const setModel = vi.fn(async () => undefined);
+
+    await expect(
+      requireVerifiedAcpxModel(
+        { getStatus, setModel },
+        resolveQualifiedAcpxProfile("codex", "gpt-5.6-sol"),
+      ),
+    ).resolves.toMatchObject({
+      models: { currentModelId: "gpt-5.6-sol" },
+    });
+    expect(setModel).not.toHaveBeenCalled();
+  });
+
+  it("selects Claude's canonical model and normalizes its ACP selector", async () => {
+    const setModel = vi.fn(async () => undefined);
+    const getStatus = vi.fn(async () => ({
+      models: {
+        currentModelId: "sonnet",
+        availableModelIds: ["default", "sonnet", "opus"],
+      },
+    }));
+
+    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).toHaveBeenCalledTimes(1);
+    expect(setModel).toHaveBeenCalledWith("claude-sonnet-5");
+    expect(getStatus).toHaveBeenCalledTimes(2);
+  });
+
+  it("selects a stale default before accepting an exact-selector profile", async () => {
+    let selected = false;
+    const setModel = vi.fn(async () => {
+      selected = true;
+    });
+    const getStatus = vi.fn(async () => ({
+      models: {
+        currentModelId: selected ? "gpt-5.6-sol" : "default",
+        availableModelIds: ["default", "gpt-5.6-sol"],
+      },
+    }));
+
+    await requireVerifiedAcpxModel(
+      { getStatus, setModel },
+      resolveQualifiedAcpxProfile("codex", "gpt-5.6-sol"),
+    );
+    expect(setModel).toHaveBeenCalledWith("gpt-5.6-sol");
+  });
+
+  it("fails closed when status or model selection is unavailable", async () => {
+    const profile = resolveQualifiedAcpxProfile("codex", "gpt-5.6-sol");
+    await expect(requireVerifiedAcpxModel({}, profile)).rejects.toThrow(
+      /cannot verify its effective model/,
+    );
+    await expect(
+      requireVerifiedAcpxModel(
+        {
+          getStatus: async () => ({
+            models: { currentModelId: "default", availableModelIds: [] },
+          }),
+        },
+        profile,
+      ),
+    ).rejects.toThrow(/config options/);
+  });
+
+  it("rejects a provider that ignores the qualified model selection", async () => {
+    const profile = resolveQualifiedAcpxProfile(
+      "pi",
+      "openrouter/deepseek/deepseek-v4-flash-0731",
+    );
+    await expect(
+      requireVerifiedAcpxModel(
+        {
+          getStatus: async () => ({
+            models: {
+              currentModelId: "openrouter/other",
+              availableModelIds: ["openrouter/other"],
+            },
+          }),
+          setModel: async () => undefined,
+        },
+        profile,
+      ),
+    ).rejects.toThrow(/effective model mismatch/);
+  });
+});
diff --git a/packages/paperclip-runner/src/drivers/acpx/model-verification.ts b/packages/paperclip-runner/src/drivers/acpx/model-verification.ts
new file mode 100644
index 00000000000..2eb49ac6e43
--- /dev/null
+++ b/packages/paperclip-runner/src/drivers/acpx/model-verification.ts
@@ -0,0 +1,74 @@
+import type { QualifiedAcpxProfile } from "./qualified-profiles.js";
+
+export interface AcpxModelStatus {
+  models?: {
+    currentModelId?: string;
+    availableModelIds?: readonly string[];
+  };
+  [key: string]: unknown;
+}
+
+export interface AcpxModelControl {
+  getStatus?: () => Promise<AcpxModelStatus>;
+  setModel?: (model: string) => Promise<void>;
+}
+
+/**
+ * Select and verify the exact qualified model before a billable prompt can be
+ * accepted. A provider selector is normalized only after ACP reports it.
+ */
+export async function requireVerifiedAcpxModel(
+  control: AcpxModelControl,
+  profile: QualifiedAcpxProfile,
+): Promise<AcpxModelStatus> {
+  if (!control.getStatus) {
+    throw new Error("ACPX agent cannot verify its effective model");
+  }
+  const requestedModel = profile.qualificationModel;
+  let status = await control.getStatus();
+  const mustSelectCanonical =
+    profile.reportedModelId !== requestedModel ||
+    status.models?.currentModelId !== requestedModel;
+  if (mustSelectCanonical) {
+    if (!control.setModel) {
+      throw new Error(
+        "ACPX agent cannot verify its canonical model through ACP config options",
+      );
+    }
+    await control.setModel(requestedModel);
+    status = await control.getStatus();
+  }
+  if (status.models?.currentModelId !== profile.reportedModelId) {
+    throw new Error(
+      `ACPX effective model mismatch: requested ${requestedModel}, expected ACP selector ${profile.reportedModelId}, received ${status.models?.currentModelId ?? "unverified"}`,
+    );
+  }
+  return normalizeQualifiedModelStatus(status, profile);
+}
+
+function normalizeQualifiedModelStatus(
+  status: AcpxModelStatus,
+  profile: QualifiedAcpxProfile,
+): AcpxModelStatus {
+  const available = status.models?.availableModelIds ?? [];
+  const normalizedAvailable = Array.from(
+    new Set(
+      available.map((modelId) =>
+        modelId === profile.reportedModelId
+          ? profile.qualificationModel
+          : modelId,
+      ),
+    ),
+  );
+  if (!normalizedAvailable.includes(profile.qualificationModel)) {
+    normalizedAvailable.push(profile.qualificationModel);
+  }
+  return {
+    ...status,
+    models: {
+      ...status.models,
+      currentModelId: profile.qualificationModel,
+      availableModelIds: normalizedAvailable,
+    },
+  };
+}