fix(validation): retain unmatched union correction details

Preserve actionable field paths and schema-declared variants for unknown or missing discriminators.

Closes #1421. Refs #1065.

src/domain/inputIssueProjection.ts

@@ -35,7 +35,23 @@ const projectIssue = (
     typeof part === "string" || typeof part === "number" ? [part] : [],
   );
   // Branch issue paths are relative to the union; branches often agree.
-  if (issue.code === "invalid_union")
+  if (issue.code === "invalid_union") {
+    // Unmatched discriminators and ambiguous unions have no branch issues.
+    // Keep their outer failure instead of flattening it into an empty list.
+    if (issue.errors.length === 0) {
+      const expected =
+        "options" in issue ? issue.options?.filter(isSafeExpected) : undefined;
+      return [
+        {
+          path,
+          reason:
+            valueAtPath(input, path) === undefined
+              ? "missing_argument"
+              : "invalid_value",
+          ...(expected === undefined ? {} : { expected }),
+        },
+      ];
+    }
     return uniqueIssues(
       issue.errors.flatMap((branch) =>
         branch.flatMap((branchIssue) =>
@@ -46,6 +62,7 @@ const projectIssue = (
         ),
       ),
     );
+  }
   if (issue.code === "invalid_key")
     return issue.issues.flatMap((keyIssue) =>
       projectIssue(

tests/boundary/cli/analysisViewCli.test.ts

@@ -80,3 +80,48 @@ cliTest("rejects a request that omits source", async ({ cli }) => {
     details: { operation: "inspect-analysis-view" },
   });
 });
+
+for (const [view, reason] of [
+  [{ kind: "unknown-view" }, "invalid_value"],
+  [{}, "missing_argument"],
+] as const) {
+  cliTest(
+    `reports correction details for ${reason} view kind`,
+    async ({ cli }) => {
+      const root = await createTestTempDirectory("rea-view-variant-");
+      const input = join(root, "view.json");
+      await writeFile(
+        input,
+        JSON.stringify({
+          source: {
+            kind: "inline",
+            evidence: analysisViewLayoutEvidence(),
+          },
+          view,
+        }),
+      );
+      const result = await cli.run({
+        arguments: ["inspect-analysis-view", input, "--json"],
+        environment: {
+          HOME: root,
+          XDG_CONFIG_HOME: root,
+          XDG_CACHE_HOME: root,
+        },
+      });
+      expect(result.exitCode).toBe(1);
+      expect(result.json).toMatchObject({
+        code: "invalid_request",
+        details: {
+          issues: [
+            {
+              path: ["view", "kind"],
+              reason,
+              expected: expect.arrayContaining(["summary", "page"]),
+            },
+          ],
+        },
+      });
+      expect(JSON.stringify(result.json)).not.toContain("unknown-view");
+    },
+  );
+}