diff --git a/.gitea/workflows/verify.yml b/.gitea/workflows/verify.yml
new file mode 100644
index 0000000..73c7a4e
--- /dev/null
+++ b/.gitea/workflows/verify.yml
@@ -0,0 +1,35 @@
+name: Verify
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+concurrency:
+  group: verify-${{ gitea.repository }}-${{ gitea.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+    timeout-minutes: 45
+    env:
+      CI: "true"
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+          cache: npm
+      - name: Select declared npm version
+        run: npm install --global npm@11.17.0
+      - name: Install dependencies
+        run: npm ci
+      - name: Audit runtime dependencies
+        run: npm audit --omit=dev --audit-level=moderate
+      - name: Check, test, and build
+        run: npm run check
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 57e294e..b925a79 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,22 @@
 All notable changes to the independently versioned Toolbox SDK packages are
 recorded here. The packages currently share one release version.
 
+## 0.3.0 — 2026-09-02
+
+### Added
+
+- Runtime-validated manifest I/O and progressive browser-capability profiles.
+- Bounded, same-origin, target-routed, expiring, one-time artifact handoffs
+  through IndexedDB, with versioned operation evidence and opaque tokens.
+
+### Security
+
+- Reject unsafe artifact names, malformed descriptors, oversized evidence,
+  excessive file counts and cross-origin handoff destinations before storage or
+  navigation.
+- Document the origin-wide IndexedDB trust boundary explicitly: target app ids
+  route transfers but cannot authorize mutually untrusted same-origin code.
+
 ## 0.2.3 — 2026-07-27
 
 ### Changed
diff --git a/README.md b/README.md
index c51c5b0..2358b97 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ tools. An app always works by itself. When it receives a trusted same-origin
 catalog URL, the same app gains a toolbox home link and an app switcher without
 becoming coupled to a portal or client-side router.
 
-Version `0.2.3` contains three publish-ready packages:
+Version `0.3.0` contains three publish-ready packages:
 
 - `@add-ideas/toolbox-contract` — types, strict v1 runtime parsing, context
   discovery/loading, resolved URLs, and contextual link helpers.
@@ -57,6 +57,14 @@ Deploy `toolbox-app.json` beside the application entry. The canonical schema is
     "indexedDb": true,
     "crossOriginIsolated": false
   },
+  "io": {
+    "accepts": [{ "mediaType": "application/pdf", "extensions": [".pdf"] }],
+    "produces": [{ "mediaType": "application/pdf", "extensions": [".pdf"] }]
+  },
+  "capabilities": {
+    "required": ["workers"],
+    "optional": ["file-system-access"]
+  },
   "privacy": {
     "processing": "local",
     "fileUploads": false,
@@ -69,12 +77,21 @@ Deploy `toolbox-app.json` beside the application entry. The canonical schema is
 }
 ```
 
-`source`, `privacy.label`, `privacy.url`, `requirements.topLevelContext`,
-`actions`, and `assets` are optional v1 additions. `toolbox-check` verifies the
-entry, icon, and every declared asset. Runtime parsers validate every known
+`source`, `privacy.label`, `privacy.url`, `requirements.topLevelContext`, `io`,
+`capabilities`, `actions`, and `assets` are optional v1 additions. `io`
+advertises accepted and produced media types/extensions; `capabilities`
+describes required and progressive browser features. `toolbox-check` verifies
+the entry, icon, and every declared asset. Runtime parsers validate every known
 field, require `schemaVersion: 1`, and deliberately discard unknown fields so
 future optional additions do not break v1 consumers.
 
+When a manifest includes `capabilities`, worker declarations are cross-checked:
+`requirements.workers: true` means the app cannot run without workers and
+therefore requires `"workers"` in `capabilities.required`. Apps with a
+main-thread fallback set the requirement to `false` and may list `"workers"` in
+`capabilities.optional` instead. Legacy v1 manifests without a capability
+profile remain valid.
+
 For typed source definitions, use the literal-preserving identity helper:
 
 ```ts
@@ -88,6 +105,24 @@ export const manifest = defineToolboxApp({
 Use `parseToolboxApp(unknownValue)` at trust boundaries; `defineToolboxApp()` is
 compile-time only and does not replace runtime parsing.
 
+## Explicit local artifact handoff
+
+`createToolboxTransfer()` stores bounded `Blob` objects in same-origin IndexedDB
+using a cryptographic, short-lived token routed to one target app. Only that
+opaque token is added to the target URL by `createToolboxTransferUrl()`. The
+target calls `consumeToolboxTransfer()` and the record is atomically deleted.
+File bytes are neither uploaded nor placed in URLs, cross-origin destinations
+are rejected, and transfers expire after fifteen minutes by default. File
+descriptors, evidence, counts, names, sizes, and lifetimes are bounded before
+IndexedDB receives them.
+
+The target app id is a routing/integrity check in this API, not a browser access
+control boundary. IndexedDB is shared by the entire origin, so any script
+running on that origin can open the transfer database directly and read or
+delete its records. Deploy only mutually trusted, reviewed Toolbox apps on one
+origin; an untrusted app must use a separate origin and cannot participate in
+this same-origin handoff.
+
 ## Catalog v1
 
 The canonical schema is
diff --git a/package-lock.json b/package-lock.json
index 3c3d0b2..0c9d21b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@add-ideas/toolbox-sdk-workspace",
-  "version": "0.2.3",
+  "version": "0.3.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@add-ideas/toolbox-sdk-workspace",
-      "version": "0.2.3",
+      "version": "0.3.0",
       "license": "Apache-2.0",
       "workspaces": [
         "packages/*"
@@ -3946,7 +3946,7 @@
     },
     "packages/contract": {
       "name": "@add-ideas/toolbox-contract",
-      "version": "0.2.3",
+      "version": "0.3.0",
       "license": "Apache-2.0",
       "engines": {
         "node": ">=20"
@@ -3954,10 +3954,10 @@
     },
     "packages/shell-react": {
       "name": "@add-ideas/toolbox-shell-react",
-      "version": "0.2.3",
+      "version": "0.3.0",
       "license": "Apache-2.0",
       "dependencies": {
-        "@add-ideas/toolbox-contract": "0.2.3"
+        "@add-ideas/toolbox-contract": "0.3.0"
       },
       "peerDependencies": {
         "react": ">=18 <20",
@@ -3966,10 +3966,10 @@
     },
     "packages/testkit": {
       "name": "@add-ideas/toolbox-testkit",
-      "version": "0.2.3",
+      "version": "0.3.0",
       "license": "Apache-2.0",
       "dependencies": {
-        "@add-ideas/toolbox-contract": "0.2.3"
+        "@add-ideas/toolbox-contract": "0.3.0"
       },
       "bin": {
         "toolbox-check": "dist/cli.js"
diff --git a/package.json b/package.json
index 5547591..2138a26 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@add-ideas/toolbox-sdk-workspace",
-  "version": "0.2.3",
+  "version": "0.3.0",
   "private": true,
   "description": "A small, framework-neutral toolbox contract with a React application shell.",
   "license": "Apache-2.0",
diff --git a/packages/contract/README.md b/packages/contract/README.md
index 529600b..b2a975f 100644
--- a/packages/contract/README.md
+++ b/packages/contract/README.md
@@ -17,6 +17,29 @@ The package also owns the versioned same-origin browser preference contract. Use
 `readToolboxPreferences()` and `writeToolboxPreferences()` to share pinned apps,
 ordering, visibility, and light/dark/system mode with the Toolbox portal.
 
+Applications can advertise accepted and produced formats through the optional
+`io` manifest profile, and required or optional browser features through
+`capabilities`. These fields are runtime validated while remaining compatible
+with existing v1 manifests. When the capability profile is present, a manifest
+that sets `requirements.workers` to `true` must also list `"workers"` in
+`capabilities.required`; progressive worker enhancements belong in
+`capabilities.optional` with the requirement set to `false`. Legacy v1 manifests
+without `capabilities` remain valid.
+
+The package also provides an explicit local artifact handoff. A sender stores
+one or more bounded `Blob` objects in same-origin IndexedDB with a
+cryptographic, short-lived token and a target routing label.
+`createToolboxTransferUrl()` places only the opaque token in the target URL;
+`consumeToolboxTransfer()` atomically consumes it once. No file bytes are put in
+a URL, uploaded, or persisted after consumption. Destination URLs must remain
+same-origin, and descriptors, evidence, file counts, total bytes, and lifetimes
+are validated and bounded before storage.
+
+All code on one origin is inside the trust boundary: same-origin scripts can
+open IndexedDB without using this API, so `targetAppId` is not authorization.
+Host mutually untrusted apps on distinct origins; they deliberately cannot use
+this transfer mechanism.
+
 See the workspace [README](https://git.add-ideas.de/lotobo/toolbox-sdk#readme)
 for the v1 document formats and full API.
 
diff --git a/packages/contract/package.json b/packages/contract/package.json
index 72801f7..93bb7db 100644
--- a/packages/contract/package.json
+++ b/packages/contract/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@add-ideas/toolbox-contract",
-  "version": "0.2.3",
+  "version": "0.3.0",
   "description": "Runtime-validated manifests, catalogs, discovery, and URL helpers for toolbox applications.",
   "license": "Apache-2.0",
   "repository": {
diff --git a/packages/contract/src/index.ts b/packages/contract/src/index.ts
index 5bed3a4..5a5f03c 100644
--- a/packages/contract/src/index.ts
+++ b/packages/contract/src/index.ts
@@ -1,6 +1,8 @@
 export {
   TOOLBOX_META_NAME,
   TOOLBOX_QUERY_PARAMETER,
+  TOOLBOX_TRANSFER_QUERY_PARAMETER,
+  TOOLBOX_ARTIFACT_VERSION,
   TOOLBOX_SCHEMA_VERSION,
   ToolboxError,
   ToolboxValidationError,
@@ -26,6 +28,9 @@ export type {
   ToolboxDiscoverySource,
   ToolboxErrorCode,
   ToolboxIntegration,
+  ToolboxFormat,
+  ToolboxIoProfile,
+  ToolboxCapabilityProfile,
   ToolboxLaunchMode,
   ToolboxPrivacy,
   ToolboxRequirements,
@@ -53,6 +58,24 @@ export {
   loadToolboxCatalog,
   loadToolboxContext,
 } from "./load.js";
+export {
+  consumeToolboxTransfer,
+  createToolboxTransfer,
+  createToolboxTransferUrl,
+  deleteExpiredToolboxTransfers,
+  readToolboxTransferToken,
+} from "./transfer.js";
+export type {
+  ToolboxArtifactDescriptor,
+  ToolboxArtifactEvidence,
+  ToolboxArtifactFile,
+  ToolboxArtifactSource,
+  ToolboxTransfer,
+  ToolboxTransferCreateInput,
+  ToolboxTransferOptions,
+  ToolboxTransferStore,
+  ToolboxTransferUrlOptions,
+} from "./transfer.js";
 export {
   TOOLBOX_PREFERENCES_KEY,
   defaultToolboxPreferences,
diff --git a/packages/contract/src/parse.ts b/packages/contract/src/parse.ts
index 9b54683..42b1cc6 100644
--- a/packages/contract/src/parse.ts
+++ b/packages/contract/src/parse.ts
@@ -9,6 +9,9 @@ import {
   type ToolboxCatalogManifestEntry,
   type ToolboxCatalogTheme,
   type ToolboxIntegration,
+  type ToolboxIoProfile,
+  type ToolboxFormat,
+  type ToolboxCapabilityProfile,
   type ToolboxLaunchMode,
   type ToolboxPrivacy,
   type ToolboxRequirements,
@@ -21,6 +24,9 @@ type UnknownRecord = Record<string, unknown>;
 const ID_PATTERN = /^[a-z0-9]+(?:[._-][a-z0-9]+)*$/;
 const WEB_PROTOCOLS = new Set(["http:", "https:"]);
 const REFERENCE_BASE = "https://toolbox.invalid/";
+const MEDIA_TYPE_PATTERN =
+  /^(?:\*|[a-z0-9!#$&^_.+-]+)\/(?:\*|[a-z0-9!#$&^_.+-]+)$/iu;
+const EXTENSION_PATTERN = /^\.[a-z0-9][a-z0-9._+-]*$/iu;
 
 function recordAt(
   value: unknown,
@@ -186,6 +192,107 @@ function stringListAt(
   });
 }
 
+function identifierListAt(
+  object: UnknownRecord,
+  key: string,
+  path: string,
+  issues: string[],
+): readonly string[] {
+  const values = stringListAt(object, key, path, issues);
+  values.forEach((value, index) => {
+    if (!ID_PATTERN.test(value)) {
+      issues.push(`${path}.${key}[${index}] must be a lowercase toolbox id`);
+    }
+  });
+  return values.filter((value) => ID_PATTERN.test(value));
+}
+
+function parseFormats(
+  value: unknown,
+  path: string,
+  issues: string[],
+): readonly ToolboxFormat[] {
+  if (!Array.isArray(value)) {
+    issues.push(`${path} must be an array`);
+    return [];
+  }
+  const identities = new Set<string>();
+  return value.flatMap((item, index) => {
+    const itemPath = `${path}[${index}]`;
+    const object = recordAt(item, itemPath, issues);
+    const mediaType = stringAt(object, "mediaType", itemPath, issues);
+    const extensions = stringListAt(object, "extensions", itemPath, issues);
+    const label = stringAt(object, "label", itemPath, issues, {
+      optional: true,
+    });
+    if (mediaType !== undefined && !MEDIA_TYPE_PATTERN.test(mediaType)) {
+      issues.push(`${itemPath}.mediaType must be an Internet media type`);
+    }
+    extensions.forEach((extension, extensionIndex) => {
+      if (!EXTENSION_PATTERN.test(extension)) {
+        issues.push(
+          `${itemPath}.extensions[${extensionIndex}] must start with a dot`,
+        );
+      }
+    });
+    if (
+      mediaType === undefined ||
+      !MEDIA_TYPE_PATTERN.test(mediaType) ||
+      extensions.some((extension) => !EXTENSION_PATTERN.test(extension))
+    ) {
+      return [];
+    }
+    const normalizedMediaType = mediaType.toLowerCase();
+    const normalizedExtensions = extensions.map((extension) =>
+      extension.toLowerCase(),
+    );
+    const identity = `${normalizedMediaType}\u0000${normalizedExtensions.join(",")}`;
+    if (identities.has(identity)) {
+      issues.push(`${itemPath} duplicates an earlier format`);
+      return [];
+    }
+    identities.add(identity);
+    return [
+      {
+        mediaType: normalizedMediaType,
+        extensions: normalizedExtensions,
+        ...(label === undefined ? {} : { label }),
+      },
+    ];
+  });
+}
+
+function parseIoProfile(
+  value: unknown,
+  path: string,
+  issues: string[],
+): ToolboxIoProfile | undefined {
+  const object = recordAt(value, path, issues);
+  const accepts = parseFormats(object.accepts, `${path}.accepts`, issues);
+  const produces = parseFormats(object.produces, `${path}.produces`, issues);
+  return { accepts, produces };
+}
+
+function parseCapabilities(
+  value: unknown,
+  path: string,
+  issues: string[],
+): ToolboxCapabilityProfile | undefined {
+  const object = recordAt(value, path, issues);
+  const required = identifierListAt(object, "required", path, issues);
+  const optional = identifierListAt(object, "optional", path, issues);
+  const requiredSet = new Set(required);
+  optional.forEach((capability, index) => {
+    if (requiredSet.has(capability)) {
+      issues.push(`${path}.optional[${index}] is already required`);
+    }
+  });
+  return {
+    required,
+    optional: optional.filter((item) => !requiredSet.has(item)),
+  };
+}
+
 function parsePrivacy(
   value: unknown,
   path: string,
@@ -384,6 +491,25 @@ export function parseToolboxApp(value: unknown): ToolboxAppManifest {
     "$.requirements",
     issues,
   );
+  const io =
+    "io" in object ? parseIoProfile(object.io, "$.io", issues) : undefined;
+  const capabilities =
+    "capabilities" in object
+      ? parseCapabilities(object.capabilities, "$.capabilities", issues)
+      : undefined;
+  if (requirements !== undefined && capabilities !== undefined) {
+    const workersRequired = capabilities.required.includes("workers");
+    if (requirements.workers && !workersRequired) {
+      issues.push(
+        "$.capabilities.required must include workers when $.requirements.workers is true",
+      );
+    }
+    if (!requirements.workers && workersRequired) {
+      issues.push(
+        "$.capabilities.required must not include workers when $.requirements.workers is false",
+      );
+    }
+  }
   const privacy = parsePrivacy(object.privacy, "$.privacy", issues);
   const source =
     "source" in object
@@ -424,6 +550,8 @@ export function parseToolboxApp(value: unknown): ToolboxAppManifest {
     tags,
     integration,
     requirements,
+    ...(io === undefined ? {} : { io }),
+    ...(capabilities === undefined ? {} : { capabilities }),
     privacy,
     ...(source === undefined ? {} : { source }),
     ...(actions === undefined ? {} : { actions }),
diff --git a/packages/contract/src/transfer.ts b/packages/contract/src/transfer.ts
new file mode 100644
index 0000000..5fdeb11
--- /dev/null
+++ b/packages/contract/src/transfer.ts
@@ -0,0 +1,477 @@
+import {
+  TOOLBOX_ARTIFACT_VERSION,
+  TOOLBOX_TRANSFER_QUERY_PARAMETER,
+} from "./types.js";
+
+const DATABASE_NAME = "add-ideas-toolbox-transfers-v1";
+const STORE_NAME = "transfers";
+const DEFAULT_TTL_MS = 15 * 60 * 1000;
+const MAX_TTL_MS = 60 * 60 * 1000;
+const DEFAULT_MAX_BYTES = 512 * 1024 * 1024;
+const MAX_FILES = 128;
+const MAX_NAME_CHARACTERS = 255;
+const MAX_EVIDENCE_BYTES = 1024 * 1024;
+const APP_ID_PATTERN = /^[a-z0-9]+(?:[._-][a-z0-9]+)*$/;
+const TOKEN_PATTERN = /^[A-Za-z0-9_-]{22}$/;
+const MEDIA_TYPE_PATTERN =
+  /^[a-z0-9!#$&^_.+-]+\/[a-z0-9!#$&^_.+-]+(?:\s*;\s*[a-z0-9!#$&^_.+-]+=(?:[a-z0-9!#$&^_.+-]+|"[^"]*"))*$/iu;
+
+export interface ToolboxArtifactSource {
+  appId: string;
+  appVersion?: string;
+}
+
+export interface ToolboxArtifactDescriptor {
+  name: string;
+  mediaType: string;
+  size: number;
+  lastModified?: number;
+  sha256?: string;
+}
+
+export interface ToolboxArtifactFile extends ToolboxArtifactDescriptor {
+  blob: Blob;
+}
+
+export interface ToolboxArtifactEvidence {
+  formatVersion: string;
+  operation?: string;
+  engine?: string;
+  settings?: Readonly<Record<string, unknown>>;
+  warnings?: readonly string[];
+}
+
+export interface ToolboxTransfer {
+  artifactVersion: typeof TOOLBOX_ARTIFACT_VERSION;
+  token: string;
+  source: ToolboxArtifactSource;
+  targetAppId: string;
+  createdAt: number;
+  expiresAt: number;
+  files: readonly ToolboxArtifactFile[];
+  evidence?: ToolboxArtifactEvidence;
+}
+
+export interface ToolboxTransferCreateInput {
+  source: ToolboxArtifactSource;
+  targetAppId: string;
+  files: readonly ToolboxArtifactFile[];
+  evidence?: ToolboxArtifactEvidence;
+  ttlMs?: number;
+  maxBytes?: number;
+}
+
+export interface ToolboxTransferStore {
+  put(transfer: ToolboxTransfer): Promise<void>;
+  take(
+    token: string,
+    expectedTargetAppId: string,
+    now: number,
+  ): Promise<ToolboxTransfer | undefined>;
+  deleteExpired(now: number): Promise<number>;
+}
+
+export interface ToolboxTransferOptions {
+  store?: ToolboxTransferStore;
+  indexedDB?: IDBFactory;
+  crypto?: Pick<Crypto, "getRandomValues">;
+  now?: () => number;
+}
+
+export interface ToolboxTransferUrlOptions {
+  location?: string | URL;
+}
+
+function openDatabase(factory: IDBFactory): Promise<IDBDatabase> {
+  return new Promise((resolve, reject) => {
+    const request = factory.open(DATABASE_NAME, 1);
+    request.onupgradeneeded = () => {
+      const database = request.result;
+      if (!database.objectStoreNames.contains(STORE_NAME)) {
+        const store = database.createObjectStore(STORE_NAME, {
+          keyPath: "token",
+        });
+        store.createIndex("expiresAt", "expiresAt");
+      }
+    };
+    request.onerror = () =>
+      reject(request.error ?? new Error("IndexedDB open failed"));
+    request.onblocked = () => reject(new Error("IndexedDB upgrade is blocked"));
+    request.onsuccess = () => resolve(request.result);
+  });
+}
+
+function requestResult<T>(request: IDBRequest<T>): Promise<T> {
+  return new Promise((resolve, reject) => {
+    request.onerror = () =>
+      reject(request.error ?? new Error("IndexedDB request failed"));
+    request.onsuccess = () => resolve(request.result);
+  });
+}
+
+function transactionComplete(transaction: IDBTransaction): Promise<void> {
+  return new Promise((resolve, reject) => {
+    transaction.oncomplete = () => resolve();
+    transaction.onabort = () =>
+      reject(transaction.error ?? new Error("IndexedDB transaction aborted"));
+    transaction.onerror = () =>
+      reject(transaction.error ?? new Error("IndexedDB transaction failed"));
+  });
+}
+
+class IndexedDbTransferStore implements ToolboxTransferStore {
+  constructor(private readonly factory: IDBFactory) {}
+
+  async put(transfer: ToolboxTransfer): Promise<void> {
+    const database = await openDatabase(this.factory);
+    try {
+      const transaction = database.transaction(STORE_NAME, "readwrite");
+      transaction.objectStore(STORE_NAME).put(transfer);
+      await transactionComplete(transaction);
+    } finally {
+      database.close();
+    }
+  }
+
+  async take(
+    token: string,
+    expectedTargetAppId: string,
+    now: number,
+  ): Promise<ToolboxTransfer | undefined> {
+    const database = await openDatabase(this.factory);
+    try {
+      const transaction = database.transaction(STORE_NAME, "readwrite");
+      const store = transaction.objectStore(STORE_NAME);
+      const value = await requestResult(store.get(token));
+      const transfer = value as ToolboxTransfer | undefined;
+      if (
+        transfer !== undefined &&
+        transfer.targetAppId !== expectedTargetAppId
+      ) {
+        transaction.abort();
+        throw new Error(
+          "Artifact transfer was addressed to another application",
+        );
+      }
+      if (transfer !== undefined) store.delete(token);
+      await transactionComplete(transaction);
+      return transfer === undefined || transfer.expiresAt <= now
+        ? undefined
+        : transfer;
+    } finally {
+      database.close();
+    }
+  }
+
+  async deleteExpired(now: number): Promise<number> {
+    const database = await openDatabase(this.factory);
+    let count = 0;
+    try {
+      const transaction = database.transaction(STORE_NAME, "readwrite");
+      const index = transaction.objectStore(STORE_NAME).index("expiresAt");
+      await new Promise<void>((resolve, reject) => {
+        const request = index.openCursor(IDBKeyRange.upperBound(now));
+        request.onerror = () =>
+          reject(request.error ?? new Error("IndexedDB cursor failed"));
+        request.onsuccess = () => {
+          const cursor = request.result;
+          if (cursor === null) {
+            resolve();
+            return;
+          }
+          cursor.delete();
+          count += 1;
+          cursor.continue();
+        };
+      });
+      await transactionComplete(transaction);
+      return count;
+    } finally {
+      database.close();
+    }
+  }
+}
+
+function defaultStore(options: ToolboxTransferOptions): ToolboxTransferStore {
+  const factory = options.indexedDB ?? globalThis.indexedDB;
+  if (factory === undefined) throw new Error("IndexedDB is not available");
+  return new IndexedDbTransferStore(factory);
+}
+
+function assertAppId(value: string, label: string): void {
+  if (!APP_ID_PATTERN.test(value))
+    throw new TypeError(`${label} is not a toolbox app id`);
+}
+
+function normalizedFile(file: ToolboxArtifactFile): ToolboxArtifactFile {
+  if (!(file.blob instanceof Blob))
+    throw new TypeError("Artifact file blob is invalid");
+  const hasControlCharacter = Array.from(file.name).some((character) => {
+    const point = character.codePointAt(0)!;
+    return point <= 0x1f || point === 0x7f;
+  });
+  if (
+    file.name.trim() === "" ||
+    Array.from(file.name).length > MAX_NAME_CHARACTERS ||
+    hasControlCharacter ||
+    file.name.includes("/") ||
+    file.name.includes("\\")
+  ) {
+    throw new TypeError("Artifact file name is invalid");
+  }
+  if (
+    !Number.isSafeInteger(file.size) ||
+    file.size < 0 ||
+    file.size !== file.blob.size
+  ) {
+    throw new TypeError(`Artifact size does not match ${file.name}`);
+  }
+  if (file.sha256 !== undefined && !/^[a-f0-9]{64}$/u.test(file.sha256)) {
+    throw new TypeError(`Artifact SHA-256 is invalid for ${file.name}`);
+  }
+  if (
+    file.lastModified !== undefined &&
+    (!Number.isSafeInteger(file.lastModified) || file.lastModified < 0)
+  ) {
+    throw new TypeError(
+      `Artifact modification time is invalid for ${file.name}`,
+    );
+  }
+  const mediaType = file.mediaType || "application/octet-stream";
+  if (mediaType.length > 255 || !MEDIA_TYPE_PATTERN.test(mediaType)) {
+    throw new TypeError(`Artifact media type is invalid for ${file.name}`);
+  }
+  return { ...file, mediaType };
+}
+
+function normalizedEvidence(
+  evidence: ToolboxArtifactEvidence | undefined,
+): ToolboxArtifactEvidence | undefined {
+  if (evidence === undefined) return undefined;
+  if (
+    typeof evidence.formatVersion !== "string" ||
+    evidence.formatVersion.trim() === "" ||
+    evidence.formatVersion.length > 64
+  ) {
+    throw new TypeError("Artifact evidence formatVersion is invalid");
+  }
+  for (const [label, value] of [
+    ["operation", evidence.operation],
+    ["engine", evidence.engine],
+  ] as const) {
+    if (
+      value !== undefined &&
+      (typeof value !== "string" || value.length > 256)
+    ) {
+      throw new TypeError(`Artifact evidence ${label} is invalid`);
+    }
+  }
+  if (
+    evidence.warnings !== undefined &&
+    (!Array.isArray(evidence.warnings) ||
+      evidence.warnings.length > 100 ||
+      evidence.warnings.some(
+        (warning) => typeof warning !== "string" || warning.length > 1_024,
+      ))
+  ) {
+    throw new TypeError("Artifact evidence warnings are invalid");
+  }
+  let serialized: string;
+  try {
+    serialized = JSON.stringify(evidence);
+  } catch {
+    throw new TypeError("Artifact evidence must be JSON-serializable");
+  }
+  if (
+    serialized === undefined ||
+    new TextEncoder().encode(serialized).byteLength > MAX_EVIDENCE_BYTES
+  ) {
+    throw new RangeError("Artifact evidence exceeds the 1 MiB limit");
+  }
+  return evidence;
+}
+
+function tokenFrom(random: Pick<Crypto, "getRandomValues">): string {
+  const bytes = random.getRandomValues(new Uint8Array(16));
+  let binary = "";
+  bytes.forEach((value) => {
+    binary += String.fromCharCode(value);
+  });
+  return btoa(binary)
+    .replaceAll("+", "-")
+    .replaceAll("/", "_")
+    .replace(/=+$/u, "");
+}
+
+function validatedStoredTransfer(
+  value: ToolboxTransfer,
+  token: string,
+  expectedTargetAppId: string,
+  now: number,
+): ToolboxTransfer {
+  if (
+    value.artifactVersion !== TOOLBOX_ARTIFACT_VERSION ||
+    value.token !== token ||
+    value.targetAppId !== expectedTargetAppId
+  ) {
+    throw new TypeError("Stored artifact transfer identity is invalid");
+  }
+  if (typeof value.source?.appId !== "string") {
+    throw new TypeError("Stored source app id is invalid");
+  }
+  assertAppId(value.source.appId, "Stored source app id");
+  if (
+    value.source.appVersion !== undefined &&
+    (typeof value.source.appVersion !== "string" ||
+      value.source.appVersion.trim() === "" ||
+      value.source.appVersion.length > 64)
+  ) {
+    throw new TypeError("Stored source app version is invalid");
+  }
+  if (
+    !Number.isSafeInteger(value.createdAt) ||
+    !Number.isSafeInteger(value.expiresAt) ||
+    value.createdAt < 0 ||
+    value.expiresAt <= value.createdAt ||
+    value.expiresAt - value.createdAt > MAX_TTL_MS ||
+    value.expiresAt <= now
+  ) {
+    throw new TypeError("Stored artifact transfer lifetime is invalid");
+  }
+  if (
+    !Array.isArray(value.files) ||
+    value.files.length === 0 ||
+    value.files.length > MAX_FILES
+  ) {
+    throw new RangeError("Stored artifact transfer file count is invalid");
+  }
+  const files = value.files.map(normalizedFile);
+  const totalBytes = files.reduce((total, file) => total + file.size, 0);
+  if (!Number.isSafeInteger(totalBytes) || totalBytes > DEFAULT_MAX_BYTES) {
+    throw new RangeError("Stored artifact transfer exceeds the byte limit");
+  }
+  const evidence = normalizedEvidence(value.evidence);
+  return {
+    ...value,
+    source: { ...value.source },
+    files,
+    ...(evidence === undefined ? {} : { evidence }),
+  };
+}
+
+export async function createToolboxTransfer(
+  input: ToolboxTransferCreateInput,
+  options: ToolboxTransferOptions = {},
+): Promise<ToolboxTransfer> {
+  assertAppId(input.source.appId, "Source app id");
+  assertAppId(input.targetAppId, "Target app id");
+  if (
+    input.source.appVersion !== undefined &&
+    (input.source.appVersion.trim() === "" ||
+      input.source.appVersion.length > 64)
+  ) {
+    throw new TypeError("Source app version is invalid");
+  }
+  if (input.files.length === 0 || input.files.length > MAX_FILES) {
+    throw new RangeError(`Artifact transfers require 1–${MAX_FILES} files`);
+  }
+  const files = input.files.map(normalizedFile);
+  const evidence = normalizedEvidence(input.evidence);
+  const totalBytes = files.reduce((total, file) => total + file.size, 0);
+  const maxBytes = input.maxBytes ?? DEFAULT_MAX_BYTES;
+  if (
+    !Number.isSafeInteger(maxBytes) ||
+    maxBytes <= 0 ||
+    maxBytes > DEFAULT_MAX_BYTES
+  ) {
+    throw new RangeError("Artifact transfer byte limit is invalid");
+  }
+  if (totalBytes > maxBytes)
+    throw new RangeError(
+      `Artifact transfer exceeds the ${maxBytes}-byte limit`,
+    );
+  const ttlMs = input.ttlMs ?? DEFAULT_TTL_MS;
+  if (!Number.isSafeInteger(ttlMs) || ttlMs <= 0 || ttlMs > MAX_TTL_MS) {
+    throw new RangeError(`Artifact TTL must be between 1 and ${MAX_TTL_MS} ms`);
+  }
+  const now = (options.now ?? Date.now)();
+  if (
+    !Number.isSafeInteger(now) ||
+    now < 0 ||
+    now + ttlMs > Number.MAX_SAFE_INTEGER
+  )
+    throw new RangeError("Artifact transfer creation time is invalid");
+  const random = options.crypto ?? globalThis.crypto;
+  if (random === undefined)
+    throw new Error("Cryptographic randomness is not available");
+  const transfer: ToolboxTransfer = {
+    artifactVersion: TOOLBOX_ARTIFACT_VERSION,
+    token: tokenFrom(random),
+    source: input.source,
+    targetAppId: input.targetAppId,
+    createdAt: now,
+    expiresAt: now + ttlMs,
+    files,
+    ...(evidence === undefined ? {} : { evidence }),
+  };
+  await (options.store ?? defaultStore(options)).put(transfer);
+  return transfer;
+}
+
+export async function consumeToolboxTransfer(
+  token: string,
+  expectedTargetAppId: string,
+  options: ToolboxTransferOptions = {},
+): Promise<ToolboxTransfer | undefined> {
+  if (!TOKEN_PATTERN.test(token))
+    throw new TypeError("Artifact token is invalid");
+  assertAppId(expectedTargetAppId, "Target app id");
+  const now = (options.now ?? Date.now)();
+  const transfer = await (options.store ?? defaultStore(options)).take(
+    token,
+    expectedTargetAppId,
+    now,
+  );
+  if (transfer === undefined) return undefined;
+  return validatedStoredTransfer(transfer, token, expectedTargetAppId, now);
+}
+
+export async function deleteExpiredToolboxTransfers(
+  options: ToolboxTransferOptions = {},
+): Promise<number> {
+  return (options.store ?? defaultStore(options)).deleteExpired(
+    (options.now ?? Date.now)(),
+  );
+}
+
+export function createToolboxTransferUrl(
+  target: string | URL,
+  token: string,
+  options: ToolboxTransferUrlOptions = {},
+): URL {
+  if (!TOKEN_PATTERN.test(token))
+    throw new TypeError("Artifact token is invalid");
+  const location = options.location ?? globalThis.location?.href;
+  if (location === undefined) {
+    throw new Error("Current location is required for a safe artifact handoff");
+  }
+  const base = new URL(location);
+  const url = new URL(target, base);
+  if (url.origin !== base.origin) {
+    throw new TypeError("Artifact transfers must remain on the current origin");
+  }
+  url.searchParams.set(TOOLBOX_TRANSFER_QUERY_PARAMETER, token);
+  return url;
+}
+
+export function readToolboxTransferToken(
+  location: string | URL = globalThis.location.href,
+): string | undefined {
+  const token = new URL(location).searchParams.get(
+    TOOLBOX_TRANSFER_QUERY_PARAMETER,
+  );
+  if (token === null) return undefined;
+  if (!TOKEN_PATTERN.test(token))
+    throw new TypeError("Artifact token is invalid");
+  return token;
+}
diff --git a/packages/contract/src/types.ts b/packages/contract/src/types.ts
index 699773e..b955c24 100644
--- a/packages/contract/src/types.ts
+++ b/packages/contract/src/types.ts
@@ -1,6 +1,8 @@
 export const TOOLBOX_SCHEMA_VERSION = 1 as const;
 export const TOOLBOX_QUERY_PARAMETER = "toolbox" as const;
 export const TOOLBOX_META_NAME = "toolbox" as const;
+export const TOOLBOX_TRANSFER_QUERY_PARAMETER = "toolbox-transfer" as const;
+export const TOOLBOX_ARTIFACT_VERSION = 1 as const;
 
 export interface ToolboxAction {
   id: string;
@@ -32,6 +34,22 @@ export interface ToolboxRequirements {
   topLevelContext?: boolean;
 }
 
+export interface ToolboxFormat {
+  mediaType: string;
+  extensions: readonly string[];
+  label?: string;
+}
+
+export interface ToolboxIoProfile {
+  accepts: readonly ToolboxFormat[];
+  produces: readonly ToolboxFormat[];
+}
+
+export interface ToolboxCapabilityProfile {
+  required: readonly string[];
+  optional: readonly string[];
+}
+
 export interface ToolboxSource {
   repository: string;
   license: string;
@@ -49,6 +67,8 @@ export interface ToolboxAppManifest {
   tags: readonly string[];
   integration: ToolboxIntegration;
   requirements: ToolboxRequirements;
+  io?: ToolboxIoProfile;
+  capabilities?: ToolboxCapabilityProfile;
   privacy: ToolboxPrivacy;
   source?: ToolboxSource;
   actions?: readonly ToolboxAction[];
diff --git a/packages/contract/test/contract.test.ts b/packages/contract/test/contract.test.ts
index c3c00a5..6bf5897 100644
--- a/packages/contract/test/contract.test.ts
+++ b/packages/contract/test/contract.test.ts
@@ -33,6 +33,10 @@ const app = (
     indexedDb: true,
     crossOriginIsolated: false,
   },
+  capabilities: {
+    required: ["workers"],
+    optional: [],
+  },
   privacy: {
     processing: "local",
     fileUploads: false,
@@ -117,6 +121,86 @@ describe("v1 runtime parsing", () => {
     ).toThrow(/absolute HTTP\(S\) URL/u);
   });
 
+  it("normalizes declared formats and capability profiles", () => {
+    const parsed = parseToolboxApp(
+      app({
+        io: {
+          accepts: [
+            {
+              mediaType: "Application/PDF",
+              extensions: [".PDF"],
+              label: "PDF",
+            },
+          ],
+          produces: [{ mediaType: "image/*", extensions: [".png"] }],
+        },
+        capabilities: {
+          required: ["workers"],
+          optional: ["file-system-access"],
+        },
+      }),
+    );
+    expect(parsed.io?.accepts[0]).toEqual({
+      mediaType: "application/pdf",
+      extensions: [".pdf"],
+      label: "PDF",
+    });
+    expect(parsed.capabilities).toEqual({
+      required: ["workers"],
+      optional: ["file-system-access"],
+    });
+  });
+
+  it("rejects malformed formats and duplicate capabilities", () => {
+    expect(() =>
+      parseToolboxApp(
+        app({
+          io: {
+            accepts: [{ mediaType: "pdf", extensions: ["pdf"] }],
+            produces: [],
+          },
+        }),
+      ),
+    ).toThrow(/mediaType|start with a dot/u);
+    expect(() =>
+      parseToolboxApp(
+        app({
+          capabilities: { required: ["workers"], optional: ["workers"] },
+        }),
+      ),
+    ).toThrow(/already required/u);
+  });
+
+  it("keeps worker requirements and required capabilities consistent", () => {
+    const legacyManifest = app();
+    delete legacyManifest.capabilities;
+    expect(parseToolboxApp(legacyManifest).requirements.workers).toBe(true);
+
+    expect(() =>
+      parseToolboxApp(
+        app({
+          capabilities: { required: [], optional: ["workers"] },
+        }),
+      ),
+    ).toThrow(/required must include workers.*requirements\.workers is true/u);
+
+    expect(() =>
+      parseToolboxApp(
+        app({
+          requirements: {
+            secureContext: true,
+            workers: false,
+            indexedDb: true,
+            crossOriginIsolated: false,
+          },
+          capabilities: { required: ["workers"], optional: [] },
+        }),
+      ),
+    ).toThrow(
+      /required must not include workers.*requirements\.workers is false/u,
+    );
+  });
+
   it("parses manifest references and external inline catalog entries", () => {
     const parsed = parseToolboxCatalog(
       catalog({
diff --git a/packages/contract/test/schema-parity.test.ts b/packages/contract/test/schema-parity.test.ts
index e878139..1371ef4 100644
--- a/packages/contract/test/schema-parity.test.ts
+++ b/packages/contract/test/schema-parity.test.ts
@@ -124,6 +124,38 @@ describe("canonical schema and runtime parser parity", () => {
         source: { repository: "HTTPS:example.test", license: "MIT" },
       }),
     ],
+    [
+      "a required worker capability paired with a worker requirement",
+      () => ({
+        ...validApp(),
+        requirements: {
+          secureContext: false,
+          workers: true,
+          indexedDb: false,
+          crossOriginIsolated: false,
+        },
+        capabilities: { required: ["workers"], optional: [] },
+      }),
+    ],
+    [
+      "an optional worker capability without a worker requirement",
+      () => ({
+        ...validApp(),
+        capabilities: { required: [], optional: ["workers"] },
+      }),
+    ],
+    [
+      "a legacy worker requirement without a capability profile",
+      () => ({
+        ...validApp(),
+        requirements: {
+          secureContext: false,
+          workers: true,
+          indexedDb: false,
+          crossOriginIsolated: false,
+        },
+      }),
+    ],
   ];
 
   it.each(acceptedApps)("accepts %s", (_label, fixture) => {
@@ -175,6 +207,26 @@ describe("canonical schema and runtime parser parity", () => {
         actions: [{ id: "docs", label: "  ", url: "./docs" }],
       }),
     ],
+    [
+      "a worker requirement without a required worker capability",
+      () => ({
+        ...validApp(),
+        requirements: {
+          secureContext: false,
+          workers: true,
+          indexedDb: false,
+          crossOriginIsolated: false,
+        },
+        capabilities: { required: [], optional: ["workers"] },
+      }),
+    ],
+    [
+      "a required worker capability with workers disabled",
+      () => ({
+        ...validApp(),
+        capabilities: { required: ["workers"], optional: [] },
+      }),
+    ],
   ];
 
   it.each(rejectedApps)("rejects %s", (_label, fixture) => {
diff --git a/packages/contract/test/transfer.test.ts b/packages/contract/test/transfer.test.ts
new file mode 100644
index 0000000..bf5e565
--- /dev/null
+++ b/packages/contract/test/transfer.test.ts
@@ -0,0 +1,202 @@
+import {
+  consumeToolboxTransfer,
+  createToolboxTransfer,
+  createToolboxTransferUrl,
+  readToolboxTransferToken,
+  type ToolboxTransfer,
+  type ToolboxTransferStore,
+} from "../src/index.js";
+import { describe, expect, it } from "vitest";
+
+class MemoryStore implements ToolboxTransferStore {
+  readonly values = new Map<string, ToolboxTransfer>();
+
+  async put(transfer: ToolboxTransfer): Promise<void> {
+    this.values.set(transfer.token, transfer);
+  }
+
+  async take(
+    token: string,
+    expectedTargetAppId: string,
+    now: number,
+  ): Promise<ToolboxTransfer | undefined> {
+    const value = this.values.get(token);
+    if (value !== undefined && value.targetAppId !== expectedTargetAppId) {
+      throw new Error("Artifact transfer was addressed to another application");
+    }
+    this.values.delete(token);
+    return value === undefined || value.expiresAt <= now ? undefined : value;
+  }
+
+  async deleteExpired(now: number): Promise<number> {
+    let count = 0;
+    for (const [token, value] of this.values) {
+      if (value.expiresAt <= now) {
+        this.values.delete(token);
+        count += 1;
+      }
+    }
+    return count;
+  }
+}
+
+const deterministicCrypto = {
+  getRandomValues<T extends ArrayBufferView | null>(array: T): T {
+    if (array instanceof Uint8Array)
+      array.forEach((_value, index) => (array[index] = index));
+    return array;
+  },
+};
+
+describe("one-time artifact transfers", () => {
+  it("stores, addresses and consumes an artifact exactly once", async () => {
+    const store = new MemoryStore();
+    const blob = new Blob(["hello"], { type: "text/plain" });
+    const transfer = await createToolboxTransfer(
+      {
+        source: { appId: "de.add-ideas.file-tools", appVersion: "1.0.0" },
+        targetAppId: "de.add-ideas.text-tools",
+        files: [
+          { blob, name: "hello.txt", mediaType: blob.type, size: blob.size },
+        ],
+      },
+      { store, crypto: deterministicCrypto, now: () => 1_000 },
+    );
+    expect(transfer.token).toHaveLength(22);
+    const url = createToolboxTransferUrl(
+      "https://tools.test/apps/text/",
+      transfer.token,
+      { location: "https://tools.test/apps/file/" },
+    );
+    expect(readToolboxTransferToken(url)).toBe(transfer.token);
+    const consumed = await consumeToolboxTransfer(
+      transfer.token,
+      "de.add-ideas.text-tools",
+      { store, now: () => 2_000 },
+    );
+    expect(await consumed?.files[0]?.blob.text()).toBe("hello");
+    expect(
+      await consumeToolboxTransfer(transfer.token, "de.add-ideas.text-tools", {
+        store,
+        now: () => 2_000,
+      }),
+    ).toBeUndefined();
+  });
+
+  it("rejects expired, oversized and wrongly addressed transfers", async () => {
+    const store = new MemoryStore();
+    const blob = new Blob(["hello"]);
+    const transfer = await createToolboxTransfer(
+      {
+        source: { appId: "source" },
+        targetAppId: "target",
+        ttlMs: 10,
+        files: [{ blob, name: "a.bin", mediaType: "", size: blob.size }],
+      },
+      { store, crypto: deterministicCrypto, now: () => 10 },
+    );
+    await expect(
+      consumeToolboxTransfer(transfer.token, "target", {
+        store,
+        now: () => 20,
+      }),
+    ).resolves.toBeUndefined();
+    await expect(
+      createToolboxTransfer(
+        {
+          source: { appId: "source" },
+          targetAppId: "target",
+          maxBytes: 4,
+          files: [{ blob, name: "a.bin", mediaType: "", size: blob.size }],
+        },
+        { store, crypto: deterministicCrypto },
+      ),
+    ).rejects.toThrow(/exceeds/u);
+    await expect(
+      createToolboxTransfer(
+        {
+          source: { appId: "source" },
+          targetAppId: "target",
+          maxBytes: 512 * 1024 * 1024 + 1,
+          files: [{ blob, name: "a.bin", mediaType: "", size: blob.size }],
+        },
+        { store, crypto: deterministicCrypto },
+      ),
+    ).rejects.toThrow(/invalid/iu);
+    await expect(
+      createToolboxTransfer(
+        {
+          source: { appId: "source" },
+          targetAppId: "target",
+          files: [{ blob, name: "a.bin", mediaType: "", size: blob.size }],
+        },
+        { store, crypto: deterministicCrypto, now: () => Number.NaN },
+      ),
+    ).rejects.toThrow(/creation time/iu);
+
+    const addressed = await createToolboxTransfer(
+      {
+        source: { appId: "source" },
+        targetAppId: "target",
+        files: [{ blob, name: "a.bin", mediaType: "", size: blob.size }],
+      },
+      { store, crypto: deterministicCrypto },
+    );
+    await expect(
+      consumeToolboxTransfer(addressed.token, "another-target", { store }),
+    ).rejects.toThrow(/another application/u);
+  });
+
+  it("keeps opaque handoff tokens on-origin and rejects unsafe descriptors", async () => {
+    const store = new MemoryStore();
+    const blob = new Blob(["hello"]);
+    await expect(
+      createToolboxTransfer(
+        {
+          source: { appId: "source" },
+          targetAppId: "target",
+          files: [
+            {
+              blob,
+              name: "../hello.txt",
+              mediaType: "text/plain",
+              size: blob.size,
+            },
+          ],
+        },
+        { store, crypto: deterministicCrypto },
+      ),
+    ).rejects.toThrow(/name is invalid/u);
+    expect(() =>
+      createToolboxTransferUrl(
+        "https://other.test/apps/text/",
+        "AAECAwQFBgcICQoLDA0ODw",
+        { location: "https://tools.test/apps/file/" },
+      ),
+    ).toThrow(/current origin/u);
+  });
+
+  it("revalidates same-origin storage records at the consuming trust boundary", async () => {
+    const store = new MemoryStore();
+    const blob = new Blob(["hello"]);
+    const transfer = await createToolboxTransfer(
+      {
+        source: { appId: "source" },
+        targetAppId: "target",
+        files: [{ blob, name: "hello.txt", mediaType: "text/plain", size: 5 }],
+      },
+      { store, crypto: deterministicCrypto, now: () => 100 },
+    );
+    store.values.set(transfer.token, {
+      ...transfer,
+      artifactVersion: 99 as 1,
+    });
+    await expect(
+      consumeToolboxTransfer(transfer.token, "target", {
+        store,
+        now: () => 200,
+      }),
+    ).rejects.toThrow(/identity is invalid/u);
+    expect(store.values.has(transfer.token)).toBe(false);
+  });
+});
diff --git a/packages/shell-react/package.json b/packages/shell-react/package.json
index 1d09c41..3a6323f 100644
--- a/packages/shell-react/package.json
+++ b/packages/shell-react/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@add-ideas/toolbox-shell-react",
-  "version": "0.2.3",
+  "version": "0.3.0",
   "description": "A lightweight React application shell for toolbox-compatible browser applications.",
   "license": "Apache-2.0",
   "repository": {
@@ -38,7 +38,7 @@
     "react-dom": ">=18 <20"
   },
   "dependencies": {
-    "@add-ideas/toolbox-contract": "0.2.3"
+    "@add-ideas/toolbox-contract": "0.3.0"
   },
   "scripts": {
     "build": "tsc -p tsconfig.build.json && node -e \"const fs=require('node:fs');fs.copyFileSync('src/styles.css','dist/styles.css');fs.copyFileSync('../../LICENSE','LICENSE')\"",
diff --git a/packages/shell-react/test/AppShell.test.tsx b/packages/shell-react/test/AppShell.test.tsx
index b4c84bb..d5db341 100644
--- a/packages/shell-react/test/AppShell.test.tsx
+++ b/packages/shell-react/test/AppShell.test.tsx
@@ -38,6 +38,10 @@ const currentApp: ToolboxAppManifest = {
     indexedDb: true,
     crossOriginIsolated: false,
   },
+  capabilities: {
+    required: ["workers"],
+    optional: [],
+  },
   privacy: {
     processing: "local",
     fileUploads: false,
@@ -184,10 +188,12 @@ describe("AppShell", () => {
       </AppShell>,
     );
 
-    await waitFor(() =>
-      expect(
-        document.querySelector("[data-toolbox-context='connected']"),
-      ).toBeInTheDocument(),
+    await waitFor(
+      () =>
+        expect(
+          document.querySelector("[data-toolbox-context='connected']"),
+        ).toBeInTheDocument(),
+      { timeout: 4_000 },
     );
     fireEvent.click(screen.getByRole("button", { name: "Apps" }));
     const navigation = screen.getByRole("navigation", {
diff --git a/packages/testkit/package.json b/packages/testkit/package.json
index 5ba4d04..e30ce3b 100644
--- a/packages/testkit/package.json
+++ b/packages/testkit/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@add-ideas/toolbox-testkit",
-  "version": "0.2.3",
+  "version": "0.3.0",
   "description": "Manifest, asset, and nested-deployment smoke checks for built toolbox applications.",
   "license": "Apache-2.0",
   "repository": {
@@ -37,7 +37,7 @@
   },
   "types": "./dist/index.d.ts",
   "dependencies": {
-    "@add-ideas/toolbox-contract": "0.2.3"
+    "@add-ideas/toolbox-contract": "0.3.0"
   },
   "scripts": {
     "build": "tsc -p tsconfig.build.json && node -e \"const fs=require('node:fs');fs.chmodSync('dist/cli.js',0o755);fs.copyFileSync('../../LICENSE','LICENSE')\"",
diff --git a/schemas/toolbox-app.v1.schema.json b/schemas/toolbox-app.v1.schema.json
index b8a7a11..cad4ab2 100644
--- a/schemas/toolbox-app.v1.schema.json
+++ b/schemas/toolbox-app.v1.schema.json
@@ -116,6 +116,24 @@
       },
       "additionalProperties": true
     },
+    "io": {
+      "type": "object",
+      "required": ["accepts", "produces"],
+      "properties": {
+        "accepts": { "$ref": "#/$defs/formats" },
+        "produces": { "$ref": "#/$defs/formats" }
+      },
+      "additionalProperties": true
+    },
+    "capabilities": {
+      "type": "object",
+      "required": ["required", "optional"],
+      "properties": {
+        "required": { "$ref": "#/$defs/identifierList" },
+        "optional": { "$ref": "#/$defs/identifierList" }
+      },
+      "additionalProperties": true
+    },
     "source": {
       "type": "object",
       "required": ["repository", "license"],
@@ -157,6 +175,60 @@
       "uniqueItems": true
     }
   },
+  "allOf": [
+    {
+      "if": {
+        "required": ["requirements", "capabilities"],
+        "properties": {
+          "requirements": {
+            "type": "object",
+            "required": ["workers"],
+            "properties": { "workers": { "const": true } }
+          }
+        }
+      },
+      "then": {
+        "properties": {
+          "capabilities": {
+            "type": "object",
+            "required": ["required"],
+            "properties": {
+              "required": {
+                "type": "array",
+                "contains": { "const": "workers" }
+              }
+            }
+          }
+        }
+      }
+    },
+    {
+      "if": {
+        "required": ["capabilities"],
+        "properties": {
+          "capabilities": {
+            "type": "object",
+            "required": ["required"],
+            "properties": {
+              "required": {
+                "type": "array",
+                "contains": { "const": "workers" }
+              }
+            }
+          }
+        }
+      },
+      "then": {
+        "properties": {
+          "requirements": {
+            "type": "object",
+            "required": ["workers"],
+            "properties": { "workers": { "const": true } }
+          }
+        }
+      }
+    }
+  ],
   "$defs": {
     "urlReference": {
       "type": "string",
@@ -218,6 +290,37 @@
       "items": {
         "$ref": "#/$defs/nonEmptyString"
       }
+    },
+    "identifierList": {
+      "type": "array",
+      "uniqueItems": true,
+      "items": {
+        "type": "string",
+        "pattern": "^[a-z0-9]+(?:[._-][a-z0-9]+)*$"
+      }
+    },
+    "formats": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "required": ["mediaType", "extensions"],
+        "properties": {
+          "mediaType": {
+            "type": "string",
+            "pattern": "^(?:\\*|[A-Za-z0-9!#$&^_.+-]+)/(?:\\*|[A-Za-z0-9!#$&^_.+-]+)$"
+          },
+          "extensions": {
+            "type": "array",
+            "uniqueItems": true,
+            "items": {
+              "type": "string",
+              "pattern": "^\\.[A-Za-z0-9][A-Za-z0-9._+-]*$"
+            }
+          },
+          "label": { "$ref": "#/$defs/nonEmptyString" }
+        },
+        "additionalProperties": true
+      }
     }
   },
   "additionalProperties": true