cloudflare__vinext/tests/app-elements.test.ts

import React from "react";
import fs from "node:fs";
import path from "node:path";
import { describe, expect, it } from "vite-plus/test";
import { UNMATCHED_SLOT } from "../packages/vinext/src/shims/slot.js";
import {
  APP_ARTIFACT_COMPATIBILITY_KEY,
  APP_CACHE_ENTRY_REUSE_PROOF_KEY,
  APP_DYNAMIC_STALE_TIME_KEY,
  AppElementsWire,
  APP_INTERCEPTION_KEY,
  APP_INTERCEPTION_CONTEXT_KEY,
  APP_LAYOUT_IDS_KEY,
  APP_LAYOUT_FLAGS_KEY,
  APP_ROOT_LAYOUT_KEY,
  APP_ROUTE_KEY,
  APP_BFCACHE_SEGMENT_IDENTITIES_KEY,
  APP_SKIPPED_LAYOUT_IDS_KEY,
  APP_SOURCE_PAGE_SEGMENTS_KEY,
  APP_SLOT_BINDINGS_KEY,
  APP_UNMATCHED_SLOT_WIRE_VALUE,
  buildOutgoingAppPayload,
  isAppElementsRecord,
  normalizeAppElements,
  readAppElementsMetadata,
  resolveVisitedResponseInterceptionContext,
  withLayoutFlags,
} from "../packages/vinext/src/server/app-elements.js";
import {
  APP_ELEMENTS_SCHEMA_VERSION,
  ARTIFACT_COMPATIBILITY_SCHEMA_VERSION,
  createArtifactCompatibilityEnvelope,
  evaluateArtifactCompatibility,
  RSC_PAYLOAD_SCHEMA_VERSION,
} from "../packages/vinext/src/server/artifact-compatibility.js";
import { createCacheEntryReuseProof } from "../packages/vinext/src/server/cache-proof.js";

describe("AppElementsWire", () => {
  it("exposes stable metadata keys through the codec boundary", () => {
    expect(AppElementsWire.keys.bfcacheSegmentIdentities).toBe(APP_BFCACHE_SEGMENT_IDENTITIES_KEY);
  });

  it("encodes outgoing record payloads without mutating caller-owned records", () => {
    const element = {
      "layout:/": "root-layout",
      "page:/blog": "blog-page",
    };

    const encoded = AppElementsWire.encodeOutgoingPayload({
      element,
      layoutFlags: { "layout:/": "s" },
    });

    expect(encoded).not.toBe(element);
    expect(isAppElementsRecord(encoded)).toBe(true);
    if (isAppElementsRecord(encoded)) {
      expect(encoded).toEqual({
        "layout:/": "root-layout",
        "page:/blog": "blog-page",
        [APP_ARTIFACT_COMPATIBILITY_KEY]: createArtifactCompatibilityEnvelope(),
        [APP_LAYOUT_FLAGS_KEY]: { "layout:/": "s" },
      });
    }
    expect(element).toEqual({
      "layout:/": "root-layout",
      "page:/blog": "blog-page",
    });
  });

  it("decodes wire payloads and reads metadata through one codec boundary", () => {
    const decoded = AppElementsWire.decode({
      [APP_INTERCEPTION_CONTEXT_KEY]: "/feed",
      [APP_ROOT_LAYOUT_KEY]: "/",
      [APP_ROUTE_KEY]: AppElementsWire.encodeRouteId("/photos/42", "/feed"),
      "slot:modal:/": AppElementsWire.unmatchedSlotValue,
    });

    expect(decoded["slot:modal:/"]).toBe(UNMATCHED_SLOT);
    expect(AppElementsWire.readMetadata(decoded)).toEqual({
      artifactCompatibility: createArtifactCompatibilityEnvelope(),
      interception: null,
      interceptionContext: "/feed",
      layoutIds: [],
      layoutFlags: {},
      rootLayoutTreePath: "/",
      routeId: "route:/photos/42\0/feed",
      bfcacheSegmentIdentities: {},
      skippedLayoutIds: [],
      slotBindings: [],
      sourcePage: null,
    });
  });

  it("degrades malformed optional source-page metadata to null", () => {
    const decoded = AppElementsWire.decode({
      [APP_ROOT_LAYOUT_KEY]: "/",
      [APP_ROUTE_KEY]: AppElementsWire.encodeRouteId("/dashboard", null),
      [APP_SOURCE_PAGE_SEGMENTS_KEY]: ["dashboard/page"],
    });

    expect(AppElementsWire.readMetadata(decoded).sourcePage).toBeNull();
  });

  it("reads legacy source-page strings from cached payloads", () => {
    const decoded = AppElementsWire.decode({
      [APP_ROOT_LAYOUT_KEY]: "/",
      [APP_ROUTE_KEY]: AppElementsWire.encodeRouteId("/dashboard", null),
      __sourcePage: "/(dashboard)/page",
    });

    expect(AppElementsWire.readMetadata(decoded).sourcePage).toBe("/(dashboard)/page");
  });

  it.each(["/", "//page", "dashboard/page"])(
    "omits malformed outgoing source-page metadata: %s",
    (sourcePage) => {
      const metadata = AppElementsWire.createMetadataEntries({
        interceptionContext: null,
        rootLayoutTreePath: "/",
        routeId: AppElementsWire.encodeRouteId("/dashboard", null),
        sourcePage,
      });

      expect(metadata).not.toHaveProperty(APP_SOURCE_PAGE_SEGMENTS_KEY);
    },
  );

  it("creates the canonical metadata entries for outgoing AppElements records", () => {
    const metadata = AppElementsWire.createMetadataEntries({
      interceptionContext: null,
      layoutIds: ["layout:/(dashboard)"],
      rootLayoutTreePath: "/(dashboard)",
      routeId: AppElementsWire.encodeRouteId("/dashboard", null),
      bfcacheSegmentIdentities: {
        [AppElementsWire.encodeLayoutId("/(dashboard)")]: "/dashboard",
        [AppElementsWire.encodePageId("/dashboard", null)]: "/dashboard",
      },
      sourcePage: "/(dashboard)/page",
    });

    expect(metadata).toEqual({
      [APP_INTERCEPTION_CONTEXT_KEY]: null,
      [APP_LAYOUT_IDS_KEY]: ["layout:/(dashboard)"],
      [APP_ROOT_LAYOUT_KEY]: "/(dashboard)",
      [APP_ROUTE_KEY]: "route:/dashboard",
      [APP_BFCACHE_SEGMENT_IDENTITIES_KEY]: {
        "layout:/(dashboard)": "/dashboard",
        "page:/dashboard": "/dashboard",
      },
      [APP_SOURCE_PAGE_SEGMENTS_KEY]: ["(dashboard)", "page"],
    });
  });

  it("round-trips explicit interception proof metadata through the codec", () => {
    const interception = {
      sourceMatchedUrl: "/feed",
      sourceRouteId: AppElementsWire.encodeRouteId("/feed", null),
      slotId: AppElementsWire.encodeSlotId("modal", "/feed"),
      targetMatchedUrl: "/photos/42",
      targetRouteId: AppElementsWire.encodeRouteId("/photos/42", null),
    };
    const metadata = AppElementsWire.createMetadataEntries({
      interception,
      interceptionContext: "/feed",
      rootLayoutTreePath: "/",
      routeId: AppElementsWire.encodeRouteId("/photos/42", "/feed"),
    });

    expect(metadata[APP_INTERCEPTION_KEY]).toEqual(interception);
    expect(AppElementsWire.readMetadata(metadata).interception).toEqual(interception);
  });

  it("rejects malformed path URLs in explicit interception proof metadata", () => {
    const validInterception = {
      sourceMatchedUrl: "/feed",
      sourceRouteId: AppElementsWire.encodeRouteId("/feed", null),
      slotId: AppElementsWire.encodeSlotId("modal", "/feed"),
      targetMatchedUrl: "/photos/42",
      targetRouteId: AppElementsWire.encodeRouteId("/photos/42", null),
    };
    const malformedMatchedUrls = [
      "//example.test/feed",
      "/feed?tab=latest",
      "/feed#modal",
      "/fe\0ed",
    ];

    for (const sourceMatchedUrl of malformedMatchedUrls) {
      expect(() =>
        readAppElementsMetadata(
          normalizeAppElements({
            [APP_INTERCEPTION_KEY]: {
              ...validInterception,
              sourceMatchedUrl,
            },
            [APP_ROOT_LAYOUT_KEY]: "/",
            [APP_ROUTE_KEY]: AppElementsWire.encodeRouteId("/photos/42", "/feed"),
          }),
        ),
      ).toThrow("[vinext] Invalid __interception in App Router payload: expected path URLs");
    }
  });

  it("normalizes slot binding metadata at the wire boundary", () => {
    const metadata = AppElementsWire.createMetadataEntries({
      interceptionContext: null,
      layoutIds: ["layout:/dashboard"],
      rootLayoutTreePath: "/",
      routeId: AppElementsWire.encodeRouteId("/dashboard", null),
      slotBindings: [
        {
          ownerLayoutId: "layout:/dashboard",
          slotId: "slot:team:/dashboard",
          state: "active",
        },
        {
          ownerLayoutId: "layout:/dashboard",
          slotId: "slot:analytics:/dashboard",
          state: "default",
        },
      ],
    });

    expect(metadata[APP_SLOT_BINDINGS_KEY]).toEqual([
      {
        ownerLayoutId: "layout:/dashboard",
        slotId: "slot:analytics:/dashboard",
        state: "default",
      },
      {
        ownerLayoutId: "layout:/dashboard",
        slotId: "slot:team:/dashboard",
        state: "active",
      },
    ]);
  });

  it.each([
    {
      label: "duplicate slot id",
      layoutIds: ["layout:/dashboard"],
      slotBindings: [
        { ownerLayoutId: "layout:/dashboard", slotId: "slot:team:/dashboard", state: "active" },
        { ownerLayoutId: "layout:/dashboard", slotId: "slot:team:/dashboard", state: "default" },
      ],
      message: "[vinext] Invalid __slotBindings in App Router payload: duplicate slot id",
    },
    {
      label: "owner layout not present in layoutIds",
      layoutIds: ["layout:/dashboard"],
      slotBindings: [
        { ownerLayoutId: "layout:/stale", slotId: "slot:team:/dashboard", state: "active" },
      ],
      message:
        "[vinext] Invalid __slotBindings in App Router payload: owner layout id missing from __layoutIds",
    },
  ] as const)(
    "rejects invalid slot binding metadata while creating payload entries: $label",
    ({ layoutIds, message, slotBindings }) => {
      expect(() =>
        AppElementsWire.createMetadataEntries({
          interceptionContext: null,
          layoutIds,
          rootLayoutTreePath: "/",
          routeId: AppElementsWire.encodeRouteId("/dashboard", null),
          slotBindings,
        }),
      ).toThrow(message);
    },
  );

  it("constructs and parses canonical element wire keys through the codec", () => {
    const keys = [
      AppElementsWire.encodeRouteId("/blog/[slug]", null),
      AppElementsWire.encodeRouteId("/photos/42", "/feed"),
      AppElementsWire.encodePageId("/blog/[slug]", null),
      AppElementsWire.encodeLayoutId("/(marketing)/blog/[slug]"),
      AppElementsWire.encodeTemplateId("/(marketing)/blog/[slug]"),
      AppElementsWire.encodeSlotId("modal", "/feed"),
    ];

    expect(keys).toEqual([
      "route:/blog/[slug]",
      "route:/photos/42\0/feed",
      "page:/blog/[slug]",
      "layout:/(marketing)/blog/[slug]",
      "template:/(marketing)/blog/[slug]",
      "slot:modal:/feed",
    ]);

    expect(AppElementsWire.parseElementKey(keys[0])).toEqual({
      interceptionContext: null,
      kind: "route",
      path: "/blog/[slug]",
    });
    expect(AppElementsWire.parseElementKey(keys[1])).toEqual({
      interceptionContext: "/feed",
      kind: "route",
      path: "/photos/42",
    });
    expect(AppElementsWire.parseElementKey(keys[2])).toEqual({
      interceptionContext: null,
      kind: "page",
      path: "/blog/[slug]",
    });
    expect(AppElementsWire.parseElementKey(keys[3])).toEqual({
      kind: "layout",
      treePath: "/(marketing)/blog/[slug]",
    });
    expect(AppElementsWire.parseElementKey(keys[4])).toEqual({
      kind: "template",
      treePath: "/(marketing)/blog/[slug]",
    });
    expect(AppElementsWire.parseElementKey(keys[5])).toEqual({
      kind: "slot",
      name: "modal",
      treePath: "/feed",
    });
    expect(AppElementsWire.isSlotId(keys[5])).toBe(true);
    expect(AppElementsWire.parseElementKey("__route")).toBeNull();
    expect(AppElementsWire.parseElementKey("slot:modal")).toBeNull();
  });

  it("round-trips legacy-compatible payload metadata through the codec", () => {
    const payload = AppElementsWire.encodeOutgoingPayload({
      element: {
        ...AppElementsWire.createMetadataEntries({
          interceptionContext: null,
          rootLayoutTreePath: "/",
          routeId: AppElementsWire.encodeRouteId("/dashboard", null),
        }),
        [AppElementsWire.encodeLayoutId("/")]: "layout",
        [AppElementsWire.encodePageId("/dashboard", null)]: "page",
      },
      layoutFlags: {
        [AppElementsWire.encodeLayoutId("/")]: "s",
      },
    });

    expect(isAppElementsRecord(payload)).toBe(true);
    if (!isAppElementsRecord(payload)) return;

    expect(AppElementsWire.readMetadata(payload)).toEqual({
      artifactCompatibility: createArtifactCompatibilityEnvelope(),
      interception: null,
      interceptionContext: null,
      layoutIds: [],
      layoutFlags: { [AppElementsWire.encodeLayoutId("/")]: "s" },
      rootLayoutTreePath: "/",
      routeId: "route:/dashboard",
      bfcacheSegmentIdentities: {},
      skippedLayoutIds: [],
      slotBindings: [],
      sourcePage: null,
    });
  });

  it("round-trips per-page dynamic stale time through payload metadata", () => {
    const payload = AppElementsWire.encodeOutgoingPayload({
      dynamicStaleTimeSeconds: 30,
      element: {
        ...AppElementsWire.createMetadataEntries({
          interceptionContext: null,
          rootLayoutTreePath: "/",
          routeId: AppElementsWire.encodeRouteId("/dashboard", null),
        }),
        [AppElementsWire.encodePageId("/dashboard", null)]: "page",
      },
      layoutFlags: {},
    });

    expect(isAppElementsRecord(payload)).toBe(true);
    if (!isAppElementsRecord(payload)) return;

    expect(payload[APP_DYNAMIC_STALE_TIME_KEY]).toBe(30);
    expect(AppElementsWire.readMetadata(payload).dynamicStaleTimeSeconds).toBe(30);
  });

  it("keeps legacy unmatched-slot markers compatible while parsing slot keys", () => {
    const slotId = AppElementsWire.encodeSlotId("modal", "/");
    const decoded = AppElementsWire.decode({
      [APP_ROOT_LAYOUT_KEY]: "/",
      [APP_ROUTE_KEY]: AppElementsWire.encodeRouteId("/dashboard", null),
      [slotId]: AppElementsWire.unmatchedSlotValue,
    });

    expect(decoded[slotId]).toBe(UNMATCHED_SLOT);
    expect(AppElementsWire.parseElementKey(slotId)).toEqual({
      kind: "slot",
      name: "modal",
      treePath: "/",
    });
  });

  it("keeps raw AppElements wire-key construction inside the codec boundary", () => {
    const root = path.resolve(import.meta.dirname, "..");
    const sourceRoot = path.join(root, "packages/vinext/src");
    const allowed = new Set([
      path.join(sourceRoot, "routing/app-route-graph.ts"),
      path.join(sourceRoot, "server/app-elements-wire.ts"),
    ]);
    const rawWireConstruction =
      /`(?:route|page|layout|template):\$\{|`slot:\$\{|["'](?:route|page|layout|template):["']\s*\+|["']slot:["']\s*\+|\.startsWith\(["'](?:slot|layout|page|route|template):["']\)/;

    expect(rawWireConstruction.test('"slot:" + name + ":" + treePath')).toBe(true);
    expect(rawWireConstruction.test('"layout:" + treePath')).toBe(true);
    expect(rawWireConstruction.test("key.startsWith('slot:')")).toBe(true);

    const violations: string[] = [];
    const visit = (dir: string): void => {
      for (const entry of fs.readdirSync(dir, { withFileTypes: true })) {
        const fullPath = path.join(dir, entry.name);
        if (entry.isDirectory()) {
          visit(fullPath);
          continue;
        }
        if (!entry.isFile() || !/\.(?:ts|tsx)$/.test(entry.name)) continue;
        if (allowed.has(fullPath)) continue;

        const source = fs.readFileSync(fullPath, "utf8");
        if (rawWireConstruction.test(source)) {
          violations.push(path.relative(root, fullPath));
        }
      }
    };

    visit(sourceRoot);

    expect(violations).toEqual([]);
  });
});

describe("app elements payload helpers", () => {
  it("normalizes the unmatched-slot wire marker to UNMATCHED_SLOT for slot entries", () => {
    const normalized = normalizeAppElements({
      [APP_ROOT_LAYOUT_KEY]: "/",
      [APP_ROUTE_KEY]: "route:/dashboard",
      "page:/dashboard": React.createElement("main", null, "dashboard"),
      "slot:modal:/": APP_UNMATCHED_SLOT_WIRE_VALUE,
    });

    expect(normalized["slot:modal:/"]).toBe(UNMATCHED_SLOT);
    expect(normalized["page:/dashboard"]).not.toBe(UNMATCHED_SLOT);
  });

  it("does not rewrite the unmatched-slot wire marker for non-slot entries", () => {
    const normalized = normalizeAppElements({
      [APP_ROOT_LAYOUT_KEY]: "/",
      [APP_ROUTE_KEY]: "route:/dashboard",
      "page:/dashboard": APP_UNMATCHED_SLOT_WIRE_VALUE,
    });

    expect(normalized["page:/dashboard"]).toBe(APP_UNMATCHED_SLOT_WIRE_VALUE);
  });

  it("reads route metadata from the normalized payload", () => {
    const metadata = readAppElementsMetadata(
      normalizeAppElements({
        [APP_INTERCEPTION_CONTEXT_KEY]: "/feed",
        [APP_ROOT_LAYOUT_KEY]: "/(dashboard)",
        [APP_ROUTE_KEY]: "route:/dashboard",
        "route:/dashboard": React.createElement("div", null, "route"),
      }),
    );

    expect(metadata.routeId).toBe("route:/dashboard");
    expect(metadata.interceptionContext).toBe("/feed");
    expect(metadata.rootLayoutTreePath).toBe("/(dashboard)");
  });

  it("defaults missing interception context metadata to null", () => {
    const metadata = readAppElementsMetadata(
      normalizeAppElements({
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_ROUTE_KEY]: "route:/dashboard",
        "route:/dashboard": React.createElement("div", null, "route"),
      }),
    );

    expect(metadata.interceptionContext).toBeNull();
  });

  it.each([
    {
      label: "non-string binding",
      bfcacheSegmentIdentities: {
        "page:/dashboard": "/dashboard",
        "layout:/": 123,
      },
    },
    {
      label: "non-segment element id",
      bfcacheSegmentIdentities: {
        "page:/dashboard": "/dashboard",
        "route:/dashboard": "/dashboard",
      },
    },
  ])("rejects the BFCache identity map atomically: $label", ({ bfcacheSegmentIdentities }) => {
    const metadata = readAppElementsMetadata({
      ...normalizeAppElements({
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_ROUTE_KEY]: "route:/dashboard",
      }),
      [APP_BFCACHE_SEGMENT_IDENTITIES_KEY]: bfcacheSegmentIdentities,
    });

    expect(metadata.bfcacheSegmentIdentities).toEqual({});
  });

  it("encodes intercepted route ids and cache keys with a NUL separator", () => {
    expect(AppElementsWire.encodeRouteId("/photos/42", null)).toBe("route:/photos/42");
    expect(AppElementsWire.encodeRouteId("/photos/42", "/feed")).toBe("route:/photos/42\0/feed");
    expect(AppElementsWire.encodeCacheKey("/photos/42.rsc", null)).toBe("/photos/42.rsc");
    expect(AppElementsWire.encodeCacheKey("/photos/42.rsc", "/feed")).toBe("/photos/42.rsc\0/feed");
  });

  it("preserves the request cache context when a direct-route payload omits it", () => {
    expect(resolveVisitedResponseInterceptionContext("/feed", null)).toBe("/feed");
    expect(resolveVisitedResponseInterceptionContext("/feed", "/feed")).toBe("/feed");
    expect(resolveVisitedResponseInterceptionContext("/feed", "/gallery")).toBe("/gallery");
    expect(resolveVisitedResponseInterceptionContext(null, null)).toBeNull();
  });

  it("rejects payloads with a missing __route key", () => {
    expect(() =>
      readAppElementsMetadata(
        normalizeAppElements({
          [APP_ROOT_LAYOUT_KEY]: "/",
        }),
      ),
    ).toThrow("[vinext] Missing __route string in App Router payload");
  });

  it("rejects payloads with an invalid __rootLayout value", () => {
    expect(() =>
      readAppElementsMetadata(
        normalizeAppElements({
          [APP_ROOT_LAYOUT_KEY]: 123,
          [APP_ROUTE_KEY]: "route:/dashboard",
        }),
      ),
    ).toThrow("[vinext] Invalid __rootLayout in App Router payload: expected string or null");
  });

  it("rejects payloads with a missing __rootLayout key", () => {
    expect(() =>
      readAppElementsMetadata(
        normalizeAppElements({
          [APP_ROUTE_KEY]: "route:/dashboard",
        }),
      ),
    ).toThrow("[vinext] Missing __rootLayout key in App Router payload");
  });

  it("rejects payloads with an invalid __interceptionContext value", () => {
    expect(() =>
      readAppElementsMetadata(
        normalizeAppElements({
          [APP_INTERCEPTION_CONTEXT_KEY]: 123,
          [APP_ROOT_LAYOUT_KEY]: "/",
          [APP_ROUTE_KEY]: "route:/dashboard",
        }),
      ),
    ).toThrow("[vinext] Invalid __interceptionContext in App Router payload");
  });

  it("reads layoutFlags from payload metadata", () => {
    // Layout flags are set directly on the elements object (not via
    // normalizeAppElements which expects AppWireElementValue types).
    const elements = {
      ...normalizeAppElements({
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_ROUTE_KEY]: "route:/blog",
        "page:/blog": React.createElement("div", null, "blog"),
      }),
      [APP_LAYOUT_FLAGS_KEY]: { "layout:/": "s", "layout:/blog": "d" },
    };
    const metadata = readAppElementsMetadata(elements);

    expect(metadata.layoutIds).toEqual([]);
    expect(metadata.layoutFlags).toEqual({ "layout:/": "s", "layout:/blog": "d" });
  });

  it("defaults missing layoutFlags to empty object (backward compat)", () => {
    const metadata = readAppElementsMetadata(
      normalizeAppElements({
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_ROUTE_KEY]: "route:/dashboard",
        "route:/dashboard": React.createElement("div", null, "route"),
      }),
    );

    expect(metadata.layoutIds).toEqual([]);
    expect(metadata.layoutFlags).toEqual({});
  });

  it("reads layoutIds from payload metadata", () => {
    const metadata = readAppElementsMetadata(
      normalizeAppElements({
        [APP_LAYOUT_IDS_KEY]: ["layout:/", "layout:/dashboard"],
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_ROUTE_KEY]: "route:/dashboard/settings",
        "route:/dashboard/settings": React.createElement("div", null, "route"),
      }),
    );

    expect(metadata.layoutIds).toEqual(["layout:/", "layout:/dashboard"]);
  });

  it("reads validated slot bindings from payload metadata", () => {
    const metadata = readAppElementsMetadata(
      normalizeAppElements({
        [APP_LAYOUT_IDS_KEY]: ["layout:/", "layout:/dashboard"],
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_ROUTE_KEY]: "route:/dashboard/settings",
        [APP_SLOT_BINDINGS_KEY]: [
          {
            ownerLayoutId: "layout:/dashboard",
            slotId: "slot:team:/dashboard",
            state: "default",
          },
          {
            ownerLayoutId: "layout:/dashboard",
            slotId: "slot:analytics:/dashboard",
            state: "unmatched",
          },
        ],
      }),
    );

    expect(metadata.slotBindings).toEqual([
      {
        ownerLayoutId: "layout:/dashboard",
        slotId: "slot:analytics:/dashboard",
        state: "unmatched",
      },
      {
        ownerLayoutId: "layout:/dashboard",
        slotId: "slot:team:/dashboard",
        state: "default",
      },
    ]);
  });

  it("rejects invalid layoutIds metadata", () => {
    expect(() =>
      readAppElementsMetadata({
        ...normalizeAppElements({
          [APP_ROOT_LAYOUT_KEY]: "/",
          [APP_ROUTE_KEY]: "route:/dashboard",
        }),
        [APP_LAYOUT_IDS_KEY]: ["layout:/", 1],
      }),
    ).toThrow("[vinext] Invalid __layoutIds in App Router payload: expected layout id string[]");
  });

  it.each([
    {
      label: "non-array",
      value: "layout:/dashboard",
      message:
        "[vinext] Invalid __skippedLayoutIds in App Router payload: expected layout id string[]",
    },
    {
      label: "non-string",
      value: ["layout:/", 1],
      message:
        "[vinext] Invalid __skippedLayoutIds in App Router payload: expected layout id string[]",
    },
    {
      label: "non-layout id",
      value: ["page:/dashboard"],
      message: "[vinext] Invalid __skippedLayoutIds in App Router payload: expected layout ids",
    },
  ])("rejects invalid skipped layout metadata: $label", ({ message, value }) => {
    expect(() =>
      readAppElementsMetadata({
        ...normalizeAppElements({
          [APP_ROOT_LAYOUT_KEY]: "/",
          [APP_ROUTE_KEY]: "route:/dashboard",
        }),
        [APP_SKIPPED_LAYOUT_IDS_KEY]: value,
      }),
    ).toThrow(message);
  });

  it.each([
    {
      label: "non-array",
      value: "slot:team:/dashboard",
      message: "[vinext] Invalid __slotBindings in App Router payload: expected array",
    },
    {
      label: "non-object",
      value: ["slot:team:/dashboard"],
      message: "[vinext] Invalid __slotBindings in App Router payload: expected objects",
    },
    {
      label: "non-slot id",
      value: [{ ownerLayoutId: "layout:/dashboard", slotId: "page:/dashboard", state: "active" }],
      message: "[vinext] Invalid __slotBindings in App Router payload: expected slot ids",
    },
    {
      label: "non-layout owner",
      value: [
        { ownerLayoutId: "slot:team:/dashboard", slotId: "slot:team:/dashboard", state: "active" },
      ],
      message: "[vinext] Invalid __slotBindings in App Router payload: expected owner layout ids",
    },
    {
      label: "invalid state",
      value: [
        { ownerLayoutId: "layout:/dashboard", slotId: "slot:team:/dashboard", state: "stale" },
      ],
      message: "[vinext] Invalid __slotBindings in App Router payload: expected state",
    },
    {
      label: "duplicate slot id",
      value: [
        { ownerLayoutId: "layout:/dashboard", slotId: "slot:team:/dashboard", state: "active" },
        { ownerLayoutId: "layout:/dashboard", slotId: "slot:team:/dashboard", state: "default" },
      ],
      message: "[vinext] Invalid __slotBindings in App Router payload: duplicate slot id",
    },
    {
      label: "owner layout not present in layoutIds",
      value: [{ ownerLayoutId: "layout:/stale", slotId: "slot:team:/dashboard", state: "active" }],
      message:
        "[vinext] Invalid __slotBindings in App Router payload: owner layout id missing from __layoutIds",
    },
  ])("rejects invalid slotBindings metadata: $label", ({ value, message }) => {
    expect(() =>
      readAppElementsMetadata({
        ...normalizeAppElements({
          [APP_ROOT_LAYOUT_KEY]: "/",
          [APP_ROUTE_KEY]: "route:/dashboard",
        }),
        [APP_LAYOUT_IDS_KEY]: ["layout:/dashboard"],
        [APP_SLOT_BINDINGS_KEY]: value,
      }),
    ).toThrow(message);
  });

  it.each([
    ["page id", "page:/dashboard"],
    ["slot id", "slot:modal:/dashboard"],
    ["malformed layout id", "layout:dashboard"],
  ])("rejects %s in layoutIds metadata", (_, layoutId) => {
    expect(() =>
      readAppElementsMetadata({
        ...normalizeAppElements({
          [APP_ROOT_LAYOUT_KEY]: "/",
          [APP_ROUTE_KEY]: "route:/dashboard",
        }),
        [APP_LAYOUT_IDS_KEY]: ["layout:/", layoutId],
      }),
    ).toThrow("[vinext] Invalid __layoutIds in App Router payload: expected layout ids");
  });

  it("reads artifact compatibility envelope metadata", () => {
    const envelope = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-a",
      rootBoundaryId: "root-a",
    });
    const metadata = readAppElementsMetadata({
      ...normalizeAppElements({
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_ROUTE_KEY]: "route:/dashboard",
        "route:/dashboard": React.createElement("div", null, "route"),
      }),
      [APP_ARTIFACT_COMPATIBILITY_KEY]: envelope,
    });

    expect(metadata.artifactCompatibility).toEqual(envelope);
  });

  it("defaults missing artifact compatibility to unknown proof for legacy payloads", () => {
    const metadata = readAppElementsMetadata(
      normalizeAppElements({
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_ROUTE_KEY]: "route:/dashboard",
        "route:/dashboard": React.createElement("div", null, "route"),
      }),
    );

    expect(metadata.artifactCompatibility).toEqual({
      schemaVersion: ARTIFACT_COMPATIBILITY_SCHEMA_VERSION,
      graphVersion: null,
      deploymentVersion: null,
      appElementsSchemaVersion: APP_ELEMENTS_SCHEMA_VERSION,
      rscPayloadSchemaVersion: RSC_PAYLOAD_SCHEMA_VERSION,
      rootBoundaryId: null,
      renderEpoch: null,
    });
  });

  it("defaults malformed artifact compatibility metadata to unknown proof", () => {
    const metadata = readAppElementsMetadata({
      ...normalizeAppElements({
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_ROUTE_KEY]: "route:/dashboard",
      }),
      [APP_ARTIFACT_COMPATIBILITY_KEY]: {
        schemaVersion: ARTIFACT_COMPATIBILITY_SCHEMA_VERSION,
        graphVersion: 123,
        deploymentVersion: null,
        appElementsSchemaVersion: APP_ELEMENTS_SCHEMA_VERSION,
        rscPayloadSchemaVersion: RSC_PAYLOAD_SCHEMA_VERSION,
        rootBoundaryId: null,
        renderEpoch: null,
      },
    });

    expect(metadata.artifactCompatibility).toEqual(createArtifactCompatibilityEnvelope());
  });

  it("defaults artifact compatibility with an unrecognized schema version to unknown proof", () => {
    const metadata = readAppElementsMetadata({
      ...normalizeAppElements({
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_ROUTE_KEY]: "route:/dashboard",
      }),
      [APP_ARTIFACT_COMPATIBILITY_KEY]: {
        schemaVersion: 99,
        graphVersion: null,
        deploymentVersion: null,
        appElementsSchemaVersion: APP_ELEMENTS_SCHEMA_VERSION,
        rscPayloadSchemaVersion: RSC_PAYLOAD_SCHEMA_VERSION,
        rootBoundaryId: null,
        renderEpoch: null,
      },
    });

    expect(metadata.artifactCompatibility).toEqual(createArtifactCompatibilityEnvelope());
  });

  it("defaults non-object artifact compatibility metadata to unknown proof", () => {
    const metadata = readAppElementsMetadata({
      ...normalizeAppElements({
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_ROUTE_KEY]: "route:/dashboard",
      }),
      [APP_ARTIFACT_COMPATIBILITY_KEY]: "garbage",
    });

    expect(metadata.artifactCompatibility).toEqual(createArtifactCompatibilityEnvelope());
  });
});

describe("isAppElementsRecord", () => {
  it("returns true for a plain record", () => {
    expect(isAppElementsRecord({ "page:/": "x" })).toBe(true);
  });

  it("returns false for a React element", () => {
    expect(isAppElementsRecord(React.createElement("div", null, "x"))).toBe(false);
  });

  it("returns false for null", () => {
    expect(isAppElementsRecord(null)).toBe(false);
  });

  it("returns false for an array", () => {
    expect(isAppElementsRecord([])).toBe(false);
  });

  it("returns false for a string", () => {
    expect(isAppElementsRecord("string")).toBe(false);
  });

  it("returns false for undefined", () => {
    expect(isAppElementsRecord(undefined)).toBe(false);
  });
});

describe("withLayoutFlags", () => {
  it("attaches the __layoutFlags key with the supplied value", () => {
    const input = { "page:/": "page" };
    const result = withLayoutFlags(input, { "layout:/": "s" });
    expect(result[APP_LAYOUT_FLAGS_KEY]).toEqual({ "layout:/": "s" });
  });

  it("does not mutate the input", () => {
    const input: Record<string, unknown> = { "page:/": "page", "layout:/": "layout" };
    const snapshot = structuredClone(input);
    const result = withLayoutFlags(input, { "layout:/": "d" });
    expect(result).not.toBe(input);
    expect(input).toEqual(snapshot);
    expect(Object.keys(input)).toEqual(Object.keys(snapshot));
    expect(APP_LAYOUT_FLAGS_KEY in input).toBe(false);
  });

  it("preserves other keys on the returned object", () => {
    const input = { "page:/blog": "page", "layout:/": "layout" };
    const result = withLayoutFlags(input, { "layout:/": "s" });
    expect(result["page:/blog"]).toBe("page");
    expect(result["layout:/"]).toBe("layout");
  });

  it("returns a new object with a different identity", () => {
    const input = { "page:/": "page" };
    const result = withLayoutFlags(input, {});
    expect(result).not.toBe(input);
  });
});

describe("buildOutgoingAppPayload", () => {
  it("returns a non-record element unchanged (same identity)", () => {
    const element = React.createElement("div", null, "page");
    const result = buildOutgoingAppPayload({
      element,
      layoutFlags: { "layout:/": "s" },
    });
    expect(result).toBe(element);
  });

  it("returns a new object for a record element (different identity)", () => {
    const element = { "page:/": "page" };
    const result = buildOutgoingAppPayload({
      element,
      layoutFlags: {},
    });
    expect(result).not.toBe(element);
  });

  it("does not mutate the input record", () => {
    const element: Record<string, React.ReactNode> = {
      "layout:/": "root-layout",
      "layout:/blog": "blog-layout",
      "page:/blog": "blog-page",
    };
    const snapshot = structuredClone(element);
    const result = buildOutgoingAppPayload({
      element,
      layoutFlags: { "layout:/": "s", "layout:/blog": "d" },
    });
    expect(result).not.toBe(element);
    expect(element).toEqual(snapshot);
    expect(Object.keys(element)).toEqual(Object.keys(snapshot));
    expect(APP_LAYOUT_FLAGS_KEY in element).toBe(false);
    expect(APP_ARTIFACT_COMPATIBILITY_KEY in element).toBe(false);
  });

  it("attaches __layoutFlags on the returned record", () => {
    const result = buildOutgoingAppPayload({
      element: { "page:/": "page" },
      layoutFlags: { "layout:/": "s" },
    });
    expect(isAppElementsRecord(result)).toBe(true);
    if (isAppElementsRecord(result)) {
      expect(result[APP_LAYOUT_FLAGS_KEY]).toEqual({ "layout:/": "s" });
    }
  });

  it("attaches __artifactCompatibility on the returned record", () => {
    const result = buildOutgoingAppPayload({
      element: { "page:/": "page" },
      layoutFlags: { "layout:/": "s" },
      artifactCompatibility: createArtifactCompatibilityEnvelope({
        graphVersion: "graph-a",
        deploymentVersion: "deploy-a",
        rootBoundaryId: "root-a",
      }),
    });
    expect(isAppElementsRecord(result)).toBe(true);
    if (isAppElementsRecord(result)) {
      expect(result[APP_ARTIFACT_COMPATIBILITY_KEY]).toEqual({
        schemaVersion: ARTIFACT_COMPATIBILITY_SCHEMA_VERSION,
        graphVersion: "graph-a",
        deploymentVersion: "deploy-a",
        appElementsSchemaVersion: APP_ELEMENTS_SCHEMA_VERSION,
        rscPayloadSchemaVersion: RSC_PAYLOAD_SCHEMA_VERSION,
        rootBoundaryId: "root-a",
        renderEpoch: null,
      });
    }
  });

  it("carries planner-visible cache entry reuse proof as metadata only", () => {
    const cacheEntryReuseProof = createCacheEntryReuseProof(null);
    const result = buildOutgoingAppPayload({
      element: {
        [APP_ROUTE_KEY]: "route:/dashboard",
        [APP_ROOT_LAYOUT_KEY]: "/",
        "page:/dashboard": "dashboard-page",
      },
      cacheEntryReuseProof,
      layoutFlags: { "layout:/": "s" },
    });

    expect(isAppElementsRecord(result)).toBe(true);
    if (isAppElementsRecord(result)) {
      expect(result[APP_CACHE_ENTRY_REUSE_PROOF_KEY]).toEqual(cacheEntryReuseProof);
      expect(AppElementsWire.readMetadata(result).cacheEntryReuseProof).toEqual(
        cacheEntryReuseProof,
      );
    }
  });

  it("carries source pages as segments on the wire and reconstructs the browser value", () => {
    const result = buildOutgoingAppPayload({
      element: {
        ...AppElementsWire.createMetadataEntries({
          interceptionContext: null,
          rootLayoutTreePath: "/",
          routeId: "route:/pricing",
          sourcePage: "/(marketing)/pricing/page",
        }),
        "page:/pricing": "pricing-page",
      },
      layoutFlags: { "layout:/": "s" },
    });

    expect(isAppElementsRecord(result)).toBe(true);
    if (isAppElementsRecord(result)) {
      expect(result[APP_SOURCE_PAGE_SEGMENTS_KEY]).toEqual(["(marketing)", "pricing", "page"]);
      expect(AppElementsWire.readMetadata(result).sourcePage).toBe("/(marketing)/pricing/page");
      expect(JSON.stringify(result)).not.toContain("__sourcePage");
      expect(JSON.stringify(result)).not.toContain("/(marketing)/pricing/page");
    }
  });

  it("returns canonical record keys when no skip disposition is supplied", () => {
    const result = buildOutgoingAppPayload({
      element: { "layout:/": "root-layout", "page:/": "page" },
      layoutFlags: { "layout:/": "s" },
    });
    expect(isAppElementsRecord(result)).toBe(true);
    if (isAppElementsRecord(result)) {
      expect(result["layout:/"]).toBe("root-layout");
      expect(result["page:/"]).toBe("page");
    }
  });

  it("omits only proven layout entries when static-layout skip transport is enabled", () => {
    const result = buildOutgoingAppPayload({
      element: {
        [APP_ROUTE_KEY]: "route:/dashboard",
        [APP_ROOT_LAYOUT_KEY]: "/",
        "layout:/": "root-layout",
        "layout:/dashboard": "dashboard-layout",
        "page:/dashboard": "dashboard-page",
      },
      layoutFlags: { "layout:/": "s", "layout:/dashboard": "s" },
      skipDisposition: {
        code: "SKIP_STATIC_LAYOUT_VERIFIED",
        enabled: true,
        mode: "skipStaticLayout",
        skippedEntryIds: ["layout:/dashboard", "page:/dashboard"],
      },
    });

    expect(isAppElementsRecord(result)).toBe(true);
    if (isAppElementsRecord(result)) {
      expect(result["layout:/"]).toBe("root-layout");
      expect(Object.hasOwn(result, "layout:/dashboard")).toBe(false);
      expect(result["page:/dashboard"]).toBe("dashboard-page");
      expect(result[APP_LAYOUT_FLAGS_KEY]).toEqual({
        "layout:/": "s",
        "layout:/dashboard": "s",
      });
      expect(result[APP_ROUTE_KEY]).toBe("route:/dashboard");
      expect(result[APP_ROOT_LAYOUT_KEY]).toBe("/");
      expect(result[APP_SKIPPED_LAYOUT_IDS_KEY]).toEqual(["layout:/dashboard"]);
      expect(AppElementsWire.readMetadata(result).skippedLayoutIds).toEqual(["layout:/dashboard"]);
    }
  });

  it("preserves non-layout metadata keys", () => {
    const result = buildOutgoingAppPayload({
      element: {
        [APP_ROUTE_KEY]: "route:/blog",
        [APP_ROOT_LAYOUT_KEY]: "/",
        [APP_INTERCEPTION_CONTEXT_KEY]: null,
        "layout:/": "root-layout",
        "page:/blog": "blog-page",
      },
      layoutFlags: { "layout:/": "s" },
    });
    expect(isAppElementsRecord(result)).toBe(true);
    if (isAppElementsRecord(result)) {
      expect(result[APP_ROUTE_KEY]).toBe("route:/blog");
      expect(result[APP_ROOT_LAYOUT_KEY]).toBe("/");
      expect(result[APP_INTERCEPTION_CONTEXT_KEY]).toBeNull();
      expect(result["page:/blog"]).toBe("blog-page");
      expect(result["layout:/"]).toBe("root-layout");
    }
  });
});

describe("artifact compatibility proof evaluation", () => {
  it("returns compatible only when every current proof field is known and equal", () => {
    const current = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-a",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });

    expect(evaluateArtifactCompatibility(current, current)).toEqual({
      kind: "compatible",
    });
  });

  it("falls back to renderFresh when graph compatibility is unknown", () => {
    const current = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-a",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });
    const candidate = createArtifactCompatibilityEnvelope({
      deploymentVersion: "deploy-a",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });

    expect(evaluateArtifactCompatibility(current, candidate)).toEqual({
      kind: "unknown",
      fallback: "renderFresh",
      reason: "graphVersionUnknown",
    });
  });

  it("falls back to renderFresh when deployment compatibility is unknown", () => {
    const current = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-a",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });
    const candidate = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });

    expect(evaluateArtifactCompatibility(current, candidate)).toEqual({
      kind: "unknown",
      fallback: "renderFresh",
      reason: "deploymentVersionUnknown",
    });
  });

  it("falls back to renderFresh when root boundary compatibility is unknown", () => {
    const current = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-a",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });
    const candidate = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-a",
      renderEpoch: "epoch-a",
    });

    expect(evaluateArtifactCompatibility(current, candidate)).toEqual({
      kind: "unknown",
      fallback: "renderFresh",
      reason: "rootBoundaryIdUnknown",
    });
  });

  it("does not promote matching graph and deployment metadata to reuse proof when renderEpoch is unknown", () => {
    const current = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-a",
      rootBoundaryId: "root-a",
    });
    const candidate = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-a",
      rootBoundaryId: "root-a",
    });

    expect(evaluateArtifactCompatibility(current, candidate)).toEqual({
      kind: "unknown",
      fallback: "renderFresh",
      reason: "renderEpochUnknown",
    });
  });

  it("rejects a known deployment mismatch instead of using the unknown fallback", () => {
    const current = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-a",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });
    const candidate = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-b",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });

    expect(evaluateArtifactCompatibility(current, candidate)).toEqual({
      kind: "incompatible",
      fallback: "renderFresh",
      reason: "deploymentVersionMismatch",
    });
  });

  it("accepts rolling deploy payloads when compatibility is explicitly declared", () => {
    const current = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-next",
      deploymentVersion: "deploy-canary",
      rootBoundaryId: "root-next",
      renderEpoch: "epoch-next",
    });
    const candidate = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-current",
      deploymentVersion: "deploy-stable",
      rootBoundaryId: "root-current",
      renderEpoch: "epoch-current",
    });

    expect(
      evaluateArtifactCompatibility(current, candidate, {
        compatibilityMap: {
          graphVersions: [["graph-current", "graph-next"]],
          deploymentVersions: [["deploy-stable", "deploy-canary"]],
          rootBoundaryIds: [["root-current", "root-next"]],
          renderEpochs: [["epoch-current", "epoch-next"]],
        },
      }),
    ).toEqual({ kind: "compatible" });
  });

  it("supports canary and rollback only when they share a declared compatibility set", () => {
    const rollback = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-rollback",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });
    const canary = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-canary",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });

    expect(
      evaluateArtifactCompatibility(rollback, canary, {
        compatibilityMap: {
          deploymentVersions: [["deploy-stable", "deploy-canary", "deploy-rollback"]],
        },
      }),
    ).toEqual({ kind: "compatible" });
  });

  it("does not infer transitive deployment compatibility across overlapping pairs", () => {
    const current = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-c",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });
    const candidate = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-a",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });

    expect(
      evaluateArtifactCompatibility(current, candidate, {
        compatibilityMap: {
          deploymentVersions: [
            ["deploy-a", "deploy-b"],
            ["deploy-b", "deploy-c"],
          ],
        },
      }),
    ).toEqual({
      kind: "incompatible",
      fallback: "renderFresh",
      reason: "deploymentVersionNotDeclaredCompatible",
    });
  });

  it("falls back to fresh render when a stale compatibility map lacks the rollback deploy", () => {
    const rollback = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-rollback",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });
    const staleCanary = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-a",
      deploymentVersion: "deploy-canary",
      rootBoundaryId: "root-a",
      renderEpoch: "epoch-a",
    });

    expect(
      evaluateArtifactCompatibility(rollback, staleCanary, {
        compatibilityMap: {
          deploymentVersions: [["deploy-stable", "deploy-canary"]],
        },
      }),
    ).toEqual({
      kind: "incompatible",
      fallback: "renderFresh",
      reason: "deploymentVersionNotDeclaredCompatible",
    });
  });

  it("treats old-client/new-server future compatibility metadata as unknown proof", () => {
    const current = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-current",
      deploymentVersion: "deploy-current",
      rootBoundaryId: "root-current",
      renderEpoch: "epoch-current",
    });
    const payload = {
      [APP_ROUTE_KEY]: "route:/dashboard",
      [APP_INTERCEPTION_CONTEXT_KEY]: null,
      [APP_ROOT_LAYOUT_KEY]: "/",
      [APP_ARTIFACT_COMPATIBILITY_KEY]: {
        schemaVersion: ARTIFACT_COMPATIBILITY_SCHEMA_VERSION + 1,
        graphVersion: "graph-next",
        deploymentVersion: "deploy-next",
        appElementsSchemaVersion: APP_ELEMENTS_SCHEMA_VERSION,
        rscPayloadSchemaVersion: RSC_PAYLOAD_SCHEMA_VERSION,
        rootBoundaryId: "root-next",
        renderEpoch: "epoch-next",
      },
    } satisfies Readonly<Record<string, unknown>>;

    const metadata = AppElementsWire.readMetadata(payload);

    expect(metadata.artifactCompatibility).toEqual(createArtifactCompatibilityEnvelope());
    expect(evaluateArtifactCompatibility(current, metadata.artifactCompatibility)).toEqual({
      kind: "unknown",
      fallback: "renderFresh",
      reason: "graphVersionUnknown",
    });
  });

  it("treats new-client/old-server legacy payload metadata as unknown proof", () => {
    const current = createArtifactCompatibilityEnvelope({
      graphVersion: "graph-current",
      deploymentVersion: "deploy-current",
      rootBoundaryId: "root-current",
      renderEpoch: "epoch-current",
    });
    const payload = {
      [APP_ROUTE_KEY]: "route:/dashboard",
      [APP_INTERCEPTION_CONTEXT_KEY]: null,
      [APP_ROOT_LAYOUT_KEY]: "/",
    } satisfies Readonly<Record<string, unknown>>;

    const metadata = AppElementsWire.readMetadata(payload);

    expect(metadata.artifactCompatibility).toEqual(createArtifactCompatibilityEnvelope());
    expect(evaluateArtifactCompatibility(current, metadata.artifactCompatibility)).toEqual({
      kind: "unknown",
      fallback: "renderFresh",
      reason: "graphVersionUnknown",
    });
  });
});