#Runtime, manifests, and snapshots

#What each artifact does

Three different “stats/manifest” ideas show up in Module Federation builds. Do not treat them as interchangeable:

mf-stats.json is build-focused. It carries detailed assets, exposes, remotes, shared packages, used exports, plugin/build versions, remote entry metadata, and type metadata.

mf-manifest.json is the stable runtime view distilled from those stats. Consumers can use it for dynamic type hints, preloading, and DevTools data.

The exact upstream shapes live in manifest types and stats types.

MFDoctor records:

• container id and name,
• public path,
• plugin and build versions,
• remote entry name/path/type,
• type archive/API metadata,
• expose asset lists,
• shared versions and asset lists,
• remote alias/entry/version/scope metadata.

It then compares these values with config, installed packages, and emitted assets. This catches stale output that a config-only linter cannot see.

#Per-bundler expectations

MFDoctor’s capabilities.manifest / capabilities.stats flags mean “on-disk mf-manifest.json / mf-stats.json were collected,” not “webpack compilation stats exist.” Emit defaults differ by MF plugin family:

Explicit: absence of webpack compilation stats.json on Vite / Rolldown / Vite Plus is expected. Do not treat it as a MFDoctor or adapter failure.

Related fixes (closed):

• #116 — Vite doctor/partial-analysis must suggest manifest: true, not “pass MF options,” when config is present and only artifacts are missing.
• #119 — Enhanced omitted manifest is default-on; do not fire artifact/manifest-disabled when emit (or capabilities.manifest) proves otherwise.
• #125 — Vite/Nuxt-shaped manifests (empty remoteEntry.path, publicPath: "./") are normal; artifact rules must not false-positive.

#Soak conclusions (adapters vs upstream)

From the 2026-08-01 bundler soak (reconstructions; SOAK_REPORT.md is not vendored in-tree):

• Adapters are healthy across Vite, Webpack, Rspack, and Rsbuild when MF emits the artifacts MFDoctor can read. Failures that looked like “missing manifest/stats” were usually Vite opt-in gaps or Enhanced default-emit normalization — addressed in #116 / #119 / #125.
• Modern.js core demos (modern-ssr-*, modern-data-fetch-*) failed before MFDoctor ran in the 2026-08-01 soak because @module-federation/bridge-react/size-limited-cache was missing on the soaked core branch (upstream packaging / dist drift). The package export was added by Core PR #4897 and is present in @module-federation/bridge-react@2.8.2, but the corresponding core-demo re-soak remains unverified. It was not a MFDoctor Modern adapter crash. In-repo examples/compatibility/modern smoke stays green; a full @modern-js/app-tools core-demo re-soak is still external evidence and is not covered by this partial cell. Track the final verification in #130.

#Quiet soak / demo config

For local demos and soak hosts, prefer manifest remotes, Vite manifest: true, and either loaded-first or a retry / errorLoadRemote recovery plugin so offline remotes do not drown the report:

import { federation } from "@module-federation/vite";
import { federationDoctor } from "@tonoizer/mfdoctor/vite";

const mfOptions = {
  name: "host_demo",
  // Required on Vite — Enhanced family emits by default when manifest !== false.
  manifest: true,
  // Prefer delayed failure over version-first hard startup when remotes may be offline.
  shareStrategy: "loaded-first",
  remotes: {
    // Prefer mf-manifest.json URLs when a manifest server is available.
    app1: "app1@http://127.0.0.1:3001/mf-manifest.json",
  },
  // Or: runtimePlugins: [require.resolve("@module-federation/retry-plugin")],
  shared: {
    react: { singleton: true },
    "react-dom": { singleton: true },
  },
};

export default {
  plugins: [federation(mfOptions), federationDoctor({ moduleFederation: mfOptions })],
};

See also reliability/version-first-offline-remotes and the Vite integration notes.

#Report capabilities block

After a build or mfdoctor check, inspect what MFDoctor actually collected:

jq '.capabilities' .mf/doctor/report.json
# or per-project:
jq '.capabilities' .mf/doctor/project.json

Typical keys: config, sourceImports, manifest, stats, emittedAssets, installedVersions. A Vite host with MF options but without manifest: true often shows config: true with manifest: false / stats: false — that is artifact opt-in, not missing config. The high-level capability matrix summarizes depth per bundler; this page is the detailed emit contract.

#Deployed probe

When network access is explicitly wanted, compare the build view with a live manifest:

mfdoctor probe https://cdn.example.com/mf-manifest.json --remote-entry

The probe downloads only the bounded JSON manifest. --remote-entry adds a HEAD request for the entry. It reports status and headers but does not download or execute the remote JavaScript. This is useful for stale-CDN, wrong-public-path, missing-entry, and bad-content-type checks. It cannot prove that container initialization or an exposed factory works; use runtime observability for those stages.

#Snapshot flow

At runtime, a manifest is converted into module snapshot data. The snapshot contains the resolved remote entry, public path, remote type URLs, dependent remotes, shared assets, and optional secondary tree-shaken shared artifacts. The runtime caches manifest fetches and emits RUNTIME-013 when required manifest fields are missing.

See the upstream snapshot types and snapshot loader.

#Observability

MFDoctor's default analysis is static and offline. For a live failure, use the official Observability Plugin. It can identify whether a failure occurred during manifest, remote entry, container init, expose lookup, factory execution, or shared resolution.

Do not guess from a generic network error:

1. keep the stable RUNTIME-xxx code;
2. capture the failed URL/status and original browser exception;
3. export an observability report when available;
4. correlate that export with MFDoctor build facts:

mfdoctor check --format json
mfdoctor runtime ./.mf/observability/latest.json ".mf/doctor/**/project.json"

mfdoctor runtime imports the user-supplied report, redacts secrets and full private URLs, and emits runtime/* findings that join remotes, shared packages, and init phases with .mf/doctor/project.json evidence. It does not fetch live remotes or execute remote JavaScript.

This separates a bad deployment URL from valid JavaScript that downloaded and then failed during execution.