test(routing): lock policy evidence parity across inbound protocols

tests/routing-policy-surface-parity.test.ts

@@ -0,0 +1,103 @@
+import { describe, expect, test } from "bun:test";
+
+import { chatCompletionsToResponsesBody } from "../src/chat/inbound";
+import { anthropicToResponsesTranslation } from "../src/claude/inbound";
+import { evidenceFromBody } from "../src/routing/request-evidence";
+
+const MODEL = "policy/daily";
+const EXPECTED_RICH_EVIDENCE = {
+  toolsRequired: true,
+  imageInputRequired: true,
+};
+
+describe("routing policy request evidence parity", () => {
+  test("tools and image input produce the same evidence across Responses, Chat Completions, and Claude Messages", () => {
+    const responsesBody = {
+      model: MODEL,
+      input: [{
+        type: "message",
+        role: "user",
+        content: [
+          { type: "input_text", text: "inspect this" },
+          { type: "input_image", image_url: "data:image/png;base64,AA==" },
+        ],
+      }],
+      tools: [{
+        type: "function",
+        name: "inspect",
+        parameters: { type: "object", properties: {} },
+      }],
+    };
+
+    const chatBody = chatCompletionsToResponsesBody({
+      model: MODEL,
+      messages: [{
+        role: "user",
+        content: [
+          { type: "text", text: "inspect this" },
+          { type: "image_url", image_url: { url: "data:image/png;base64,AA==" } },
+        ],
+      }],
+      tools: [{
+        type: "function",
+        function: {
+          name: "inspect",
+          parameters: { type: "object", properties: {} },
+        },
+      }],
+    });
+
+    const claudeBody = anthropicToResponsesTranslation({
+      model: MODEL,
+      max_tokens: 128,
+      messages: [{
+        role: "user",
+        content: [
+          { type: "text", text: "inspect this" },
+          {
+            type: "image",
+            source: {
+              type: "base64",
+              media_type: "image/png",
+              data: "AA==",
+            },
+          },
+        ],
+      }],
+      tools: [{
+        name: "inspect",
+        input_schema: { type: "object", properties: {} },
+      }],
+    }).body;
+
+    expect(evidenceFromBody(responsesBody)).toEqual(EXPECTED_RICH_EVIDENCE);
+    expect(evidenceFromBody(chatBody)).toEqual(EXPECTED_RICH_EVIDENCE);
+    expect(evidenceFromBody(claudeBody)).toEqual(EXPECTED_RICH_EVIDENCE);
+  });
+
+  test("plain text without tools produces no hard routing evidence on every surface", () => {
+    const responsesBody = {
+      model: MODEL,
+      input: [{
+        type: "message",
+        role: "user",
+        content: [{ type: "input_text", text: "hello" }],
+      }],
+    };
+
+    const chatBody = chatCompletionsToResponsesBody({
+      model: MODEL,
+      messages: [{ role: "user", content: "hello" }],
+    });
+
+    const claudeBody = anthropicToResponsesTranslation({
+      model: MODEL,
+      max_tokens: 128,
+      messages: [{ role: "user", content: "hello" }],
+    }).body;
+
+    expect(evidenceFromBody(responsesBody)).toEqual({});
+    expect(evidenceFromBody(chatBody)).toEqual({});
+    expect(evidenceFromBody(claudeBody)).toEqual({});
+  });
+});