feat: consume the boot payload (load-path-rework 0001 §6, client)

useProjectBoot: the tool page tries the ONE composed boot round-trip first —
its project half is the getProject shape — and falls back to the active
source's getProject on any miss (older backend, local-store slug, static
gallery), so downstream behavior without a payload is exactly pre-boot.

With a payload: seedSessionIdentity makes the /api/me flight a resolved
no-op; the synced libs source is constructed with the preloaded listing
(kind-filtered client-side by kindCounts — the same org/mirror-always +
libHasKind rule the server applies) and the batch-resolved stacks, and every
INTERNAL listing (syncState, presync, enableRealtime name-mapping) rides the
preload too; the fresh project-sync digest threads into staging so a warm
restage affirms with zero HTTP.

Measured warm load (Arduino repo-as-project): total API traffic = 1 boot
request + the ydoc-backed per-file set — /api/me, /libs, sync-stacks and
/sync/manifest all at zero.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VLSht9cadprtT2mhynawWu

web/standalone/src/components/WasmTool.tsx

@@ -30,7 +30,7 @@ import {
 } from "@/lib/config";
 import { defaultFileName, newFileTemplate, withExtension } from "@/lib/new-file";
 import { redirectTargetFor } from "@/lib/redirect";
-import { loadSessionIdentity } from "@/lib/session-identity";
+import { loadSessionIdentity, seedSessionIdentity } from "@/lib/session-identity";
 import { setTheme, useThemeValue } from "@/lib/theme";
 import { bootKicadTool } from "@/wasm/boot";
 import {
@@ -954,6 +954,7 @@ export function WasmTool({
   libsSource,
   sourceDescriptor,
   readOnly = false,
+  boot = null,
 }: {
   tool: Tool;
   slug: string;
@@ -972,6 +973,13 @@ export function WasmTool({
    * — a specific backend lib, or a local `.kicad_sym`/`.kicad_mod` file.
    */
   libsSource?: LibsSource | null;
+  /**
+   * The composed boot payload (load-path-rework 0001 §6), when the page's ONE
+   * boot round-trip answered: seeds identity, the lib listing + stack
+   * resolves, and the project sync digest. Null ⇒ each consumer uses its
+   * individual endpoint — the pre-boot behavior.
+   */
+  boot?: import("@/lib/boot-payload").BootPayload | null;
   /** Fetch one project-relative file's bytes (contract loader or local folder). */
   fetchBytes: (relPath: string) => Promise<Uint8Array>;
   /**
@@ -1639,7 +1647,9 @@ export function WasmTool({
         // parallel with the WASM download; awaited after boot, before anything
         // binds presence/comments, so presenceUser()/userSlug() speak for the
         // authenticated user (anonymous/example backends resolve to null and
-        // the pre-auth slug fallback stays).
+        // the pre-auth slug fallback stays). A boot payload already carries
+        // the /api/me shape — seeding it makes this a resolved no-op flight.
+        if (boot?.me) seedSessionIdentity(boot.me);
         const identityReady = loadSessionIdentity(API_BASE_URL);
         // Resolve the per-tool asset base at runtime (CDN manifest → versioned
         // folder, or the flat local /wasm in dev). See wasm/wasm-assets.ts.
@@ -1647,9 +1657,15 @@ export function WasmTool({
         const base = meta.base;
         // One source instance, shared by the wasm provider AND the pre-sync below
         // (libsSourceConfig builds a fresh one each call — their SyncStack caches
-        // must be the same object for the warm-up to benefit the editor).
+        // must be the same object for the warm-up to benefit the editor). A boot
+        // payload pre-seeds its lib listing + stack resolves (zero lib HTTP).
         const source =
-          libsSource !== undefined ? libsSource : libsSourceConfig(projectId);
+          libsSource !== undefined
+            ? libsSource
+            : libsSourceConfig(
+                projectId,
+                boot ? { libs: boot.libs, stacks: boot.stacks } : undefined,
+              );
         if (libsSource === undefined) ownedLibsSource = source;
         // Download-consent gate (standalone-load-ux 0001): before pulling the
         // (large) cold wasm + lib bundles, say how many MB and wait for the OK.
@@ -1897,6 +1913,8 @@ export function WasmTool({
                   scope: currentScope(),
                   scopeId,
                   projectId,
+                  // Boot's fresh digest: a warm match stages with ZERO HTTP.
+                  digest: boot?.projectSync.digest,
                 }
               : null,
           log: append,

web/standalone/src/lib/api.ts

@@ -1,6 +1,17 @@
-import type { DriftReportBody, Project, ProjectFile } from "@pcbjam/shared";
+import type {
+  DriftReportBody,
+  Project,
+  ProjectFile,
+  ProjectWithFiles,
+} from "@pcbjam/shared";
 import { useQuery } from "@tanstack/react-query";
-import { API_BASE_URL, currentScope, libsSourceConfig } from "./config";
+import {
+  API_BASE_URL,
+  currentScope,
+  libsSourceConfig,
+  PROJECT_SOURCE_KIND,
+} from "./config";
+import { fetchBootPayload, type BootPayload } from "./boot-payload";
 import { client } from "./contract-client";
 import type { LibInfo } from "@/wasm/libs/source";
 import { downloadBytes } from "./download";
@@ -72,6 +83,31 @@ export function useProject(slug: string) {
   });
 }
 
+/**
+ * The tool page's project query, boot-endpoint first (load-path-rework 0001
+ * §6): remote deployments try the ONE composed boot round-trip — its project
+ * half is exactly the getProject shape, and the extras (identity, libs,
+ * stacks, project sync digest) ride along for WasmTool. Any miss (older
+ * backend, a local-store slug answering 404, the static gallery) falls back
+ * to the active source's getProject with `boot: null`, which is exactly the
+ * pre-boot behavior everywhere downstream.
+ */
+export function useProjectBoot(slug: string) {
+  return useQuery({
+    queryKey: ["project-boot", slug],
+    queryFn: async (): Promise<{
+      data: ProjectWithFiles & { access?: "read" | "write" };
+      boot: BootPayload | null;
+    }> => {
+      if (PROJECT_SOURCE_KIND !== "static") {
+        const boot = await fetchBootPayload(currentScope(), slug);
+        if (boot) return { data: boot, boot };
+      }
+      return { data: await projectSource().getProject(slug), boot: null };
+    },
+  });
+}
+
 /**
  * File bytes from the active source (backend stream, or the static CDN
  * gallery). Pass the file's row from the current listing as `meta` when you

web/standalone/src/lib/boot-payload.ts

@@ -0,0 +1,65 @@
+import {
+  USER_HEADER,
+  type ProjectWithFiles,
+  type SyncManifest,
+  type SyncStackDescriptor,
+} from "@pcbjam/shared";
+import { API_BASE_URL, userSlug } from "./config";
+import { fileCacheValidator, pruneProjectFileCache } from "./project-file-cache";
+
+/**
+ * The ONE editor boot round-trip (load-path-rework 0001 §6):
+ * `GET /api/scopes/:scope/projects/:project/boot` composes everything the
+ * editor otherwise collects across four serial API calls — identity, the
+ * project + files + access, the visible-lib DTOs, the batch-resolved sync
+ * stacks, and the project sync-namespace manifest with its digest. Every
+ * piece is OPTIONAL downstream: an absent payload (older backend, demo
+ * gallery, local store) leaves each consumer on its individual endpoint,
+ * so this can only ever remove requests, never break a boot.
+ */
+
+/** Wire lib DTO — the `GET /libs` shape, structurally (no contract import). */
+export interface BootLibDto {
+  id: string;
+  name: string;
+  description?: string | null;
+  type: string;
+  itemCount?: number;
+  sync?: { namespace: string; bytes: number | null } | null;
+}
+
+export interface BootPayload extends ProjectWithFiles {
+  me: unknown;
+  access?: "read" | "write";
+  libs: BootLibDto[];
+  stacks: Record<string, SyncStackDescriptor | null>;
+  projectSync: { manifest: SyncManifest; digest: string };
+}
+
+/** Null on ANY failure (404 = older backend / non-boot source) — callers fall
+ *  back to the individual endpoints. */
+export async function fetchBootPayload(
+  scope: string,
+  slug: string,
+): Promise<BootPayload | null> {
+  try {
+    const res = await fetch(
+      `${API_BASE_URL}/api/scopes/${encodeURIComponent(scope)}/projects/${encodeURIComponent(slug)}/boot`,
+      { credentials: "include", headers: { [USER_HEADER]: userSlug() } },
+    );
+    if (!res.ok) return null;
+    const body = (await res.json()) as BootPayload;
+    if (!body?.project || !Array.isArray(body.files)) return null;
+    // Fresh listing = fresh cache truth (same prune the remote source's
+    // getProject performs) — the boot payload replaces that call.
+    const valid = new Map<string, string>();
+    for (const f of body.files) {
+      const v = fileCacheValidator(f);
+      if (v) valid.set(f.path, v);
+    }
+    void pruneProjectFileCache(body.project.id, valid);
+    return body;
+  } catch {
+    return null;
+  }
+}

web/standalone/src/lib/config.ts

@@ -311,7 +311,19 @@ export function modelsSourceConfig(): Model3dSource | null {
     : null;
 }
 
-export function libsSourceConfig(projectId?: string): LibsSource | null {
+/** The boot payload's lib hand-over (see wasm/libs/synced-source.ts). */
+export interface LibsBootPreload {
+  libs: import("@/wasm/libs/synced-source").PreloadedLibDto[];
+  stacks: Record<
+    string,
+    import("@pcbjam/shared").SyncStackDescriptor | null
+  >;
+}
+
+export function libsSourceConfig(
+  projectId?: string,
+  preload?: LibsBootPreload,
+): LibsSource | null {
   const kind = import.meta.env.VITE_LIBS_SOURCE ?? "remote";
   // "local" is the placeholder id for launches with no real backend project
   // (local folder, tool grid, lib-scoped open). It is NOT a project on the
@@ -338,6 +350,7 @@ export function libsSourceConfig(projectId?: string): LibsSource | null {
                   scope: currentScope(),
                   user: userSlug(),
                   project,
+                  preloaded: preload,
                   log: (m) => console.log(m),
                 },
               )

web/standalone/src/lib/session-identity.test.ts

@@ -1,6 +1,7 @@
 import { afterEach, describe, expect, it, vi } from "vitest";
 import {
   loadSessionIdentity,
+  seedSessionIdentity,
   resetSessionIdentityForTest,
   sessionIdentity,
 } from "./session-identity";
@@ -69,4 +70,18 @@ describe("loadSessionIdentity", () => {
     await loadSessionIdentity("http://api");
     expect(f).toHaveBeenCalledTimes(1);
   });
+
+  it("a seeded boot payload makes loadSessionIdentity a no-fetch resolved flight", async () => {
+    const f = vi
+      .spyOn(globalThis, "fetch")
+      .mockRejectedValue(new Error("must not fetch"));
+    seedSessionIdentity({ user: { slug: "boots", name: "Boot User" } });
+    expect(await loadSessionIdentity("http://api")).toEqual({
+      slug: "boots",
+      name: "Boot User",
+      email: undefined,
+    });
+    expect(sessionIdentity()?.slug).toBe("boots");
+    expect(f).not.toHaveBeenCalled();
+  });
 });

web/standalone/src/lib/session-identity.ts

@@ -34,19 +34,7 @@ export function loadSessionIdentity(
     pending = fetch(`${apiBase}/api/me`, { credentials: "include" })
       .then((r) => (r.ok ? r.json() : null))
       .then((body: unknown) => {
-        const u = (
-          body as {
-            user?: { slug?: unknown; name?: unknown; email?: unknown } | null;
-          } | null
-        )?.user;
-        if (u && typeof u.slug === "string" && u.slug) {
-          const email = typeof u.email === "string" && u.email ? u.email : undefined;
-          identity = {
-            slug: u.slug,
-            name: (typeof u.name === "string" && u.name) || email || u.slug,
-            email,
-          };
-        }
+        adoptMePayload(body);
         return identity;
       })
       .catch(() => null);
@@ -54,6 +42,32 @@ export function loadSessionIdentity(
   return pending;
 }
 
+/**
+ * Seed the identity from an already-fetched `/api/me`-shaped payload (the boot
+ * endpoint's `me` — load-path-rework 0001 §6), making `loadSessionIdentity`'s
+ * own fetch a no-op resolved flight. Must run BEFORE it is first called.
+ */
+export function seedSessionIdentity(me: unknown): void {
+  adoptMePayload(me);
+  pending = Promise.resolve(identity);
+}
+
+function adoptMePayload(body: unknown): void {
+  const u = (
+    body as {
+      user?: { slug?: unknown; name?: unknown; email?: unknown } | null;
+    } | null
+  )?.user;
+  if (u && typeof u.slug === "string" && u.slug) {
+    const email = typeof u.email === "string" && u.email ? u.email : undefined;
+    identity = {
+      slug: u.slug,
+      name: (typeof u.name === "string" && u.name) || email || u.slug,
+      email,
+    };
+  }
+}
+
 /** Test-only: forget the cached identity + in-flight fetch. */
 export function resetSessionIdentityForTest(): void {
   identity = null;

web/standalone/src/pages/ToolPage.tsx

@@ -5,7 +5,7 @@ import {
   createProjectFileIfMissing,
   fetchFileBytes,
   uploadFileBytes,
-  useProject,
+  useProjectBoot,
   useSourceDescriptor,
 } from "@/lib/api";
 import { docSourceConfig } from "@/lib/config";
@@ -30,7 +30,9 @@ export function ToolPage() {
     : (parseToolParam(search.get("tool")) ?? (splat ? toolForFile(splat) : null));
   const targetPath = params.tool ? undefined : splat;
 
-  const { data, isLoading, error } = useProject(slug);
+  // Boot-endpoint first (one composed round-trip); getProject fallback inside.
+  const { data: bootData, isLoading, error } = useProjectBoot(slug);
+  const data = bootData?.data;
   const { data: sourceDescriptor } = useSourceDescriptor(slug);
   // Listing rows by path, handed to fetchFileBytes so the remote source can
   // serve unchanged files from the local body cache (project-file-cache.ts).
@@ -102,6 +104,7 @@ export function ToolPage() {
         docSource={docSource}
         sourceDescriptor={sourceDescriptor}
         readOnly={readOnly}
+        boot={bootData?.boot ?? null}
       />
     </PreflightGate>
   );

web/standalone/src/wasm/kicad-runner.ts

@@ -33,6 +33,13 @@ export interface ProjectSyncConfig {
   scope: string;
   scopeId: string;
   projectId: string;
+  /**
+   * The boot payload's fresh manifest digest (load-path-rework 0001 §6). It
+   * was computed from the same listing this boot just fetched, so trusting it
+   * is exactly as current as GETting /sync/manifest ourselves — a warm match
+   * makes project staging ZERO-request. Absent ⇒ one manifest GET, as before.
+   */
+  digest?: string;
   /** Test seams (default: credentialed global fetch / IndexedDB stores). */
   fetchImpl?: typeof fetch;
   storeFactory?: ConstructorParameters<typeof SyncStack>[0]["storeFactory"];
@@ -220,6 +227,7 @@ export async function stageViaProjectSync(
         namespace: `project:${sync.scopeId}:${sync.projectId}`,
         kind: "static",
         url: `${sync.apiBase}/api/scopes/${encodeURIComponent(sync.scope)}/projects/${encodeURIComponent(opts.slug)}/sync`,
+        digest: sync.digest,
       },
     ],
     fetchImpl: credentialed,

web/standalone/src/wasm/libs/synced-source.test.ts

@@ -310,6 +310,77 @@ describe("cutover 409 → re-resolve + retry (load-path-rework 0002)", () => {
   });
 });
 
+describe("boot preload (load-path-rework 0001 §6)", () => {
+  it("serves listLibs locally (server's kind rule) and skips the stack resolve", async () => {
+    const server = await fakeServer({ "symbol/R": "(r)" });
+    const failingResolve = ((input: unknown, init?: RequestInit) => {
+      if (String(input).includes("sync-stack")) {
+        throw new Error("resolve must not be called with a preloaded stack");
+      }
+      return (server.fetchImpl as (i: unknown, x?: RequestInit) => unknown)(
+        input,
+        init,
+      );
+    }) as typeof fetch;
+    const remoteStub = {
+      listLibs: () => {
+        throw new Error("remote listLibs must not be called");
+      },
+    } as unknown as LibsSource;
+
+    const source = syncedScopeLibsSource(remoteStub, {
+      apiBase: API,
+      scope: "s",
+      user: "u",
+      fetchImpl: failingResolve,
+      storeFactory: () => memStore(),
+      channelFactory: () => server.channel,
+      preloaded: {
+        libs: [
+          { id: LIB_ID, name: "My Lib", type: "org" },
+          {
+            id: "lib-sym",
+            name: "Symbols Only",
+            type: "origin",
+            kindCounts: { symbol: 12 },
+            sync: { namespace: "origin:lib-sym@v1", bytes: 42 },
+          },
+          {
+            id: "lib-fp",
+            name: "Footprints Only",
+            type: "origin",
+            kindCounts: { footprint: 7 },
+          },
+        ],
+        stacks: {
+          [LIB_ID]: {
+            lib: { id: LIB_ID, name: "My Lib" },
+            layers: [
+              { namespace: `org:${LIB_ID}`, kind: "live", url: ROOM, writable: true },
+            ],
+          },
+        },
+      },
+    });
+
+    // Kind filter matches the server: org libs always; origins by kindCounts.
+    const symbols = await source.listLibs!("symbol");
+    expect(symbols.map((l) => l.id).sort()).toEqual([LIB_ID, "lib-sym"]);
+    expect(symbols.find((l) => l.id === "lib-sym")!.sync).toEqual({
+      namespace: "origin:lib-sym@v1",
+      bytes: 42,
+    });
+    const footprints = await source.listLibs!("footprint");
+    expect(footprints.map((l) => l.id).sort()).toEqual([LIB_ID, "lib-fp"]);
+
+    // The preloaded stack answers the per-lib resolve: a save works with the
+    // resolve endpoint hard-failing.
+    const ok = await source.saveItemBody!(LIB_ID, "symbol", "Mine", "(body)");
+    expect(ok).toBe(true);
+    source.dispose?.();
+  });
+});
+
 describe("syncedScopeLibsSource.syncState", () => {
   function scoped(libs: LibInfo[]) {
     const remote: LibsSource = {

web/standalone/src/wasm/libs/synced-source.ts

@@ -333,6 +333,20 @@ function splitPath(path: string): LibItemInfo {
  * "lazy materialization" deferred note) — same trade the lib-editor pages
  * already make.
  */
+/** A lib DTO handed over from the boot payload (structural — the wire shape
+ *  of `GET /libs`, which the boot endpoint embeds unfiltered). */
+export interface PreloadedLibDto {
+  id: string;
+  name: string;
+  description?: string | null;
+  type: string;
+  itemCount?: number;
+  /** Per-kind item counts — the client-side equivalent of the server's
+   *  `libHasKind` filter for `listLibs(kind)`. */
+  kindCounts?: Record<string, number>;
+  sync?: { namespace: string; bytes: number | null } | null;
+}
+
 export function syncedScopeLibsSource(
   remote: LibsSource,
   opts: {
@@ -341,6 +355,17 @@ export function syncedScopeLibsSource(
     user?: string;
     project?: string;
     log?: (msg: string) => void;
+    /**
+     * The boot payload's lib listing + batch-resolved stacks (load-path-rework
+     * 0001 §6): `listLibs` answers locally (kind-filtered the same way the
+     * server would) and the stack prefetch is already satisfied — a boot with
+     * this present makes ZERO lib listing/resolve requests. Absent ⇒ the
+     * individual endpoints, exactly as before.
+     */
+    preloaded?: {
+      libs: PreloadedLibDto[];
+      stacks: Record<string, SyncStackDescriptor | null>;
+    };
     fetchImpl?: typeof fetch;
     storeFactory?: (namespace: string) => LayerStore;
     channelFactory?: ChannelFactory;
@@ -352,6 +377,30 @@ export function syncedScopeLibsSource(
   // stale pin isn't retried one-by-one. Misses simply fall back per-lib, which
   // is also what happens against a backend predating the batch route.
   const batchedStacks = new Map<string, SyncStackDescriptor | null>();
+  if (opts.preloaded) {
+    for (const [id, stack] of Object.entries(opts.preloaded.stacks)) {
+      batchedStacks.set(id, stack);
+    }
+  }
+  const preloadedLibs = (kind?: string): LibInfo[] =>
+    (opts.preloaded?.libs ?? [])
+      .filter(
+        (l) =>
+          !kind ||
+          // Same rule the server applies: org libs and mirrors are
+          // kind-agnostic containers; origins/pins need >=1 item of the kind.
+          l.type === "org" ||
+          l.type === "mirror" ||
+          (l.kindCounts?.[kind] ?? 0) > 0,
+      )
+      .map((l) => ({
+        id: l.id,
+        name: l.name,
+        description: l.description ?? null,
+        type: l.type,
+        itemCount: l.itemCount,
+        sync: l.sync ?? null,
+      }));
   const forLib = (libId: string): LibsSource => {
     let src = perLib.get(libId);
     if (!src) {
@@ -408,8 +457,14 @@ export function syncedScopeLibsSource(
     }
   }
 
+  // Every internal listing goes through the preload too — syncState, presync
+  // and the realtime name-mapping otherwise each re-fetch the listing the
+  // boot payload already carried.
+  const listLibsPreferred = (kind?: string): Promise<LibInfo[]> =>
+    opts.preloaded ? Promise.resolve(preloadedLibs(kind)) : remote.listLibs(kind);
+
   return {
-    listLibs: (kind) => remote.listLibs(kind),
+    listLibs: (kind) => listLibsPreferred(kind),
     createLib: remote.createLib?.bind(remote),
     getFpIndex: remote.getFpIndex?.bind(remote),
     async syncState(kind): Promise<LibsSyncState | null> {
@@ -419,7 +474,7 @@ export function syncedScopeLibsSource(
       // is answerable from the local cache alone — no stack resolves, no
       // bundle fetches. A backend predating the `sync` field yields no
       // namespaces at all → null (unknown), never a fake all-cold answer.
-      const libs = await remote.listLibs(kind);
+      const libs = await listLibsPreferred(kind);
       const withNs = libs.filter(
         (l): l is LibInfo & { sync: { namespace: string; bytes?: number | null } } =>
           !!l.sync?.namespace,
@@ -457,7 +512,7 @@ export function syncedScopeLibsSource(
     saveItemBody: (libId, kind, name, body) =>
       forLib(libId).saveItemBody!(libId, kind, name, body),
     async presync(presyncOpts): Promise<void> {
-      const libs = await remote.listLibs(presyncOpts?.kind);
+      const libs = await listLibsPreferred(presyncOpts?.kind);
       const total = libs.length;
       let done = 0;
       presyncOpts?.onProgress?.({ done, total, current: "libraries" });
@@ -493,7 +548,7 @@ export function syncedScopeLibsSource(
       // has usually made the same call already). Names that don't resolve —
       // project-local table rows, stale nicknames — are simply not ours.
       const wanted = new Set(libNames);
-      const libs = (await remote.listLibs()).filter((l) => wanted.has(l.name));
+      const libs = (await listLibsPreferred()).filter((l) => wanted.has(l.name));
       opts.log?.(
         `[synced] realtime upgrade for ${libs.length}/${libNames.length} referenced lib(s)`,
       );

web/standalone/src/wasm/project-stage-sync.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { encodeBundle, type SyncManifest } from "@pcbjam/shared";
+import { encodeBundle, manifestDigest, type SyncManifest } from "@pcbjam/shared";
 import { memStore } from "@pcbjam/sync-client";
 import {
   stageViaProjectSync,
@@ -25,16 +25,27 @@ function fakeSyncServer(bodies: Record<string, string>) {
     frames.push([path, b]);
   }
   let bundleFetches = 0;
+  let manifestFetches = 0;
   const fetchImpl = (async (input: unknown) => {
     const url = String(input);
-    if (url.endsWith("/sync/manifest")) return Response.json(manifest);
+    if (url.endsWith("/sync/manifest")) {
+      manifestFetches += 1;
+      return Response.json(manifest);
+    }
     if (url.endsWith("/sync/bundle")) {
       bundleFetches += 1;
       return new Response(encodeBundle(manifest, frames) as BodyInit);
     }
     return new Response(null, { status: 404 });
   }) as typeof fetch;
-  return { fetchImpl, counters: { get bundleFetches() { return bundleFetches; } } };
+  return {
+    fetchImpl,
+    manifest,
+    counters: {
+      get bundleFetches() { return bundleFetches; },
+      get manifestFetches() { return manifestFetches; },
+    },
+  };
 }
 
 function syncConfig(fetchImpl: typeof fetch): ProjectSyncConfig {
@@ -118,6 +129,34 @@ describe("stageViaProjectSync", () => {
     expect(rest).toEqual(files);
   });
 
+  it("a boot digest makes the WARM restage zero-request (load-path 0001 §6)", async () => {
+    const server = fakeSyncServer({ "a.txt": "A", "b.txt": "BB" });
+    const files: ToolFile[] = [
+      { path: "a.txt", revision: 1 },
+      { path: "b.txt", revision: 1 },
+    ];
+    const config = syncConfig(server.fetchImpl); // shared stores across runs
+    const cold: string[] = [];
+    await stageViaProjectSync(
+      { slug: "p", files, projectSync: config, log: () => {} },
+      (p) => cold.push(p),
+    );
+    expect(cold.sort()).toEqual(["a.txt", "b.txt"]);
+    expect(server.counters.bundleFetches).toBe(1);
+
+    // Warm, with the boot payload's fresh digest: the stored snapshot is
+    // affirmed without even the manifest GET.
+    const digest = await manifestDigest(server.manifest);
+    const warm: string[] = [];
+    await stageViaProjectSync(
+      { slug: "p", files, projectSync: { ...config, digest }, log: () => {} },
+      (p) => warm.push(p),
+    );
+    expect(warm.sort()).toEqual(["a.txt", "b.txt"]);
+    expect(server.counters.bundleFetches).toBe(1);
+    expect(server.counters.manifestFetches).toBe(0);
+  });
+
   it("no sync config means the whole set is per-file (demo/local sources)", async () => {
     const files: ToolFile[] = [{ path: "a.txt", revision: 1 }];
     const rest = await stageViaProjectSync(