test(mcp): assert bundle path issues by field

compare_bundles reports each relative path as an invalid_format issue
instead of one joined diagnostic sentence.

tests/boundary/cli/bundleComparisonCli.test.ts

@@ -12,6 +12,7 @@ import {
   createEvidenceBundle,
   serializeEvidenceBundle,
 } from "../../../src/domain/evidenceBundle.js";
+import { parseMcpToolError } from "../../fixtures/mcpToolError.js";
 import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";
 import { cliTest } from "../../support/cli/cliFixture.js";
 
@@ -219,12 +220,15 @@ cliTest(
         name: "compare_bundles",
         arguments: { left_bundle_path: left, right_bundle_path: right },
       });
-      expect(result.isError).toBe(true);
-      expect(result.content[0]).toMatchObject({
-        text: expect.stringContaining(
-          `${rejectedField}: must be an absolute local filesystem path`,
-        ),
-      });
+      expect(parseMcpToolError(result).error.details?.issues).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({
+            path: [rejectedField],
+            reason: "invalid_format",
+            message: "must be an absolute local filesystem path",
+          }),
+        ]),
+      );
     }
 
     const absolute = await client.callTool({

tests/boundary/mcp/bundleComparisonMcp.test.ts

@@ -164,11 +164,17 @@ it("requires absolute bundle paths without changing server-cwd semantics", async
       expect(parseMcpToolError(result).error).toMatchObject({
         code: "invalid_request",
         category: "invalid_input",
-      });
-      expect(result.content[0]).toMatchObject({
-        text: expect.stringContaining(
-          `${rejectedField}: must be an absolute local filesystem path`,
-        ),
+        details: {
+          operation: "compare_bundles",
+          issues: expect.arrayContaining([
+            {
+              path: [rejectedField],
+              reason: "invalid_format",
+              expected: "regex",
+              message: "must be an absolute local filesystem path",
+            },
+          ]),
+        },
       });
     }
     expect(