review: check-consumer-config fails loudly on a nonexistent --repo path

.changeset/checker-repo-path-guard.md

@@ -0,0 +1,5 @@
+---
+"review": patch
+---
+
+check-consumer-config: fail loudly when `--repo` names a path that does not exist. The flag takes a path to the consumer checkout, but an `owner/name` argument parses fine and resolves as a relative path, so every check reported missing and the report read as a catastrophically broken install instead of a typo (hit live during the 2026-08-20 rollout; the review-consumer-bump skill documents the footgun). The checker now throws naming the bad path. Also deduplicates parseArgs's twice-declared inline arg type into one `CliArgs` alias to stay under the max-lines cap the file already sits at.

workflows/review/lib/check-consumer-config.test.ts

@@ -689,6 +689,35 @@ describe("leftover scaffolding", () => {
     });
 });
 
+describe("the repo root", () => {
+    it("throws on a --repo that is not a path on disk", () => {
+        // `--repo Khan/webapp` parses fine and resolves as a relative path;
+        // without the guard every check reports missing instead of naming
+        // the typo.
+        expect(() => check({}, {repoRoot: "Khan/webapp"})).toThrow(
+            "--repo path does not exist: Khan/webapp",
+        );
+    });
+
+    it("accepts a root that exists and prefixes every path with it", () => {
+        const inputs = Object.fromEntries(
+            Object.entries(validInstall()).map(([path, content]) => [
+                `../consumer/${path}`,
+                content,
+            ]),
+        );
+        const report = checkConsumerConfig(fakeFs(inputs), {
+            repoRoot: "../consumer",
+            checkerVersion: "1.11.0",
+        });
+        expect(codes(report, "error")).toEqual([]);
+        // Warnings too: warning-only checks (the .gitattributes lookup)
+        // also resolve through the prefixed root, and an error-only
+        // assertion cannot observe them.
+        expect(codes(report, "warning")).toEqual([]);
+    });
+});
+
 describe("parseArgs", () => {
     it("reads the flags the CLI documents", () => {
         expect(

workflows/review/lib/check-consumer-config.ts

@@ -362,6 +362,13 @@ export const checkConsumerConfig = (
     options: CheckOptions = {},
 ): ConsumerConfigReport => {
     const repoRoot = options.repoRoot ?? ".";
+    // `--repo` takes a path to the consumer checkout; an owner/name arg
+    // resolves as a relative path and every check would report missing.
+    if (repoRoot !== "." && !fs.existsSync(repoRoot)) {
+        throw new Error(
+            `--repo path does not exist: ${repoRoot} (a path to the consumer checkout, not an owner/name)`,
+        );
+    }
     const at = (p: string): string =>
         repoRoot === "." ? p : `${repoRoot}/${p}`;
     const issues: ConfigIssue[] = [];
@@ -875,25 +882,18 @@ export {renderReport};
 /* CLI                                                                       */
 /* -------------------------------------------------------------------------- */
 
-/** Parse `--flag value` arguments. Unknown flags are an error, not ignored. */
-export const parseArgs = (
-    argv: readonly string[],
-): {
+type CliArgs = {
     repoRoot?: string;
     filesFrom?: string;
     explainPath?: string;
     workflowPath?: string;
     json: boolean;
     strict: boolean;
-} => {
-    const out = {json: false, strict: false} as {
-        repoRoot?: string;
-        filesFrom?: string;
-        explainPath?: string;
-        workflowPath?: string;
-        json: boolean;
-        strict: boolean;
-    };
+};
+
+/** Parse `--flag value` arguments. Unknown flags are an error, not ignored. */
+export const parseArgs = (argv: readonly string[]): CliArgs => {
+    const out = {json: false, strict: false} as CliArgs;
     for (let i = 0; i < argv.length; i++) {
         const arg = argv[i];
         switch (arg) {