diff --git a/packages/core/src/invoke.js b/packages/core/src/invoke.js
new file mode 100644
index 00000000..5bcd4e4f
--- /dev/null
+++ b/packages/core/src/invoke.js
@@ -0,0 +1,238 @@
+import * as API from '@ucanto/interface'
+import * as DID from '@ipld/dag-ucan/did'
+import * as Invocation from './invocation.js'
+import * as Delegation from './delegation.js'
+import * as Signature from '@ipld/dag-ucan/signature'
+import * as DAG from './dag.js'
+import * as CBOR from './cbor.js'
+import { sha256 } from 'multiformats/hashes/sha2'
+
+/**
+ * Represents an Invocation builder that can be used to construct an invocation
+ * that allows us to defer signing and encoding as needed.
+ *
+ * @template {API.InstructionModel} Run
+ * @template {API.SigAlg} SigAlg
+ * @template {API.Link<API.ReceiptModel>|API.Receipt} Receipt
+ */
+class InvocationBuilder {
+  /**
+   * @param {object} options
+   * @param {API.Signer<API.DID, SigAlg>} options.issuer
+   * @param {Run} options.run
+   * @param {API.Meta} [options.meta]
+   * @param {API.Proof[]} [options.proofs]
+   * @param {Receipt} [options.cause]
+   */
+  constructor({ issuer, run, cause, meta = {}, proofs = [] }) {
+    this.issuer = issuer
+    this.run = run
+    this.cause = cause || null
+    this.meta = meta
+    this.proofs = proofs
+  }
+  async buildIPLDView({ hasher = sha256, codec = CBOR } = {}) {
+    const { meta, proofs, run, issuer, cause } = this
+    const store = DAG.createStore()
+
+    const instruction = await codec.write(run)
+    DAG.addInto(instruction, store)
+
+    const prf = []
+    // copy blocks from proofs into the store
+    for (const proof of proofs) {
+      DAG.addEveryInto(DAG.iterate(proof), store)
+      prf.push(proof.link())
+    }
+
+    // copy blocks from the receipt into the store
+    DAG.addEveryInto(DAG.iterate(cause), store)
+
+    /** @type {API.TaskModel} */
+    const task = {
+      run: instruction.cid,
+      meta,
+      prf,
+      ...(cause ? { cause: cause.link() } : {}),
+    }
+
+    const { cid } = await codec.write(task)
+    const auth = await codec.write(await authorize({ issuer, scope: [cid] }))
+    DAG.addInto(auth, store)
+
+    const invocation = { task, auth: auth.cid }
+    /** @type {API.Block<API.InvocationModel>} */
+    const root = await codec.write(invocation)
+    DAG.addInto(root, store)
+
+    return new Invocation({
+      root: { ...root, data: invocation },
+      store,
+    })
+  }
+}
+
+class Invocation {
+  /**
+   * @param {object} input
+   * @param {Required<API.Block<API.InvocationModel>>} input.root
+   * @param {DAG.BlockStore} input.store
+   */
+  constructor({ root, store }) {
+    this.root = root
+    this.store = store
+  }
+  get task() {
+    return this.root.data.task
+  }
+  get auth() {
+    const { cid, bytes } = DAG.get(this.root.data.auth, this.store)
+    const data = CBOR.decode(bytes)
+    return new Auth({ root: { cid, bytes, data }, store: this.store })
+  }
+}
+
+/**
+ * @template {API.InstructionModel} Run
+ * @implements {API.Task<Run>}
+ */
+export class Task {
+  /**
+   * @param {object} input
+   * @param {API.TaskModel<Run>} input.data
+   * @param {DAG.BlockStore} input.store
+   */
+  constructor({ data, store }) {
+    this.data = data
+    this.store = store
+  }
+
+  get run() {
+    return this.data.run
+  }
+  get meta() {
+    return this.data.meta
+  }
+  get prf() {
+    return this.data.prf
+  }
+
+  get proofs() {
+    if (this._proofs) {
+      return this._proofs
+    } else {
+      /** @type {API.Proof[]} */
+      const proofs = []
+      const { store } = this
+      // Iterate over proof links and materialize Delegation views.
+      for (const link of this.prf) {
+        const proof = Delegation.view({ root: link, blocks: store }, link)
+        proofs.push(proof)
+      }
+
+      // we cache result of this computation as this property may get accessed
+      // more than once.
+      this._proofs = proofs
+      return proofs
+    }
+  }
+
+  get instruction() {
+    /** @type {API.Block<Run>|null} */
+    const block = DAG.get(this.run, this.store, null)
+    if (block === null) {
+      return this.run
+    } else {
+      return new Instruction({
+        root: {
+          ...block,
+          data: CBOR.decode(block.bytes),
+        },
+        store: this.store,
+      })
+    }
+  }
+}
+
+/**
+ * @template {API.Ability} Op
+ * @template {API.Resource} URI
+ * @template {Record<string, unknown>} Input
+ * @implements {API.Instruction<Op, URI, Input>}
+ */
+export class Instruction {
+  /**
+   * @param {object} input
+   * @param {Required<API.Block<API.InstructionModel<Op, URI, Input>>>} input.root
+   * @param {DAG.BlockStore} input.store
+   */
+  constructor({ root, store }) {
+    this.root = root
+    this.store = store
+  }
+  link() {
+    return this.root.cid
+  }
+
+  *iterateIPLDBlocks() {
+    yield this.root
+  }
+  /**
+   * @type {Op}
+   */
+  get op() {
+    return this.root.data.op
+  }
+  get rsc() {
+    return this.root.data.rsc
+  }
+  /**
+   * @type {Input}
+   */
+  get input() {
+    return this.root.data.input
+  }
+  get nnc() {
+    return this.root.data.nnc
+  }
+
+  get nonce() {
+    return this.root.data.nnc
+  }
+}
+
+class Auth {
+  /**
+   * @param {object} input
+   * @param {Required<API.Block<API.AuthorizationModel>>} input.root
+   * @param {DAG.BlockStore} input.store
+   */
+  constructor({ root, store }) {
+    this.root = root
+    this.store = store
+  }
+  get scope() {
+    return this.root.data.scope
+  }
+  get s() {
+    return this.root.data.s
+  }
+}
+
+/**
+ * @template {API.SigAlg} SigAlg
+ * @param {object} options
+ * @param {API.Signer<API.DID, SigAlg>} options.issuer
+ * @param {API.Link[]} options.scope
+ * @returns {Promise<API.AuthorizationModel<SigAlg>>}
+ */
+const authorize = async ({ issuer, ...source }) => {
+  const scope = source.scope.sort((a, b) =>
+    a.toString().localeCompare(b.toString())
+  )
+
+  return {
+    scope,
+    s: await issuer.sign(CBOR.encode(scope)),
+  }
+}
diff --git a/packages/core/src/task.js b/packages/core/src/task.js
new file mode 100644
index 00000000..1d397d95
--- /dev/null
+++ b/packages/core/src/task.js
@@ -0,0 +1,85 @@
+// @ts-ignore
+
+import * as API from '@ucanto/interface'
+import * as DID from '@ipld/dag-ucan/did'
+import * as Invocation from './invocation.js'
+import * as Delegation from './delegation.js'
+import * as Signature from '@ipld/dag-ucan/signature'
+import * as DAG from './dag.js'
+import * as CBOR from './cbor.js'
+import * as Schema from './schema.js'
+import { sha256 } from 'multiformats/hashes/sha2'
+import { parseLink } from './lib.js'
+
+const instruction = Schema.struct({
+  rsc: Schema.string(),
+  op: Schema.string(),
+  input: Schema.dictionary({
+    key: Schema.string(),
+    value: Schema.unknown(),
+  }),
+  nnc: Schema.string(),
+})
+
+const effects = Schema.struct({
+  fork: instruction.link().array(),
+  join: instruction.link().optional(),
+})
+
+const receipt = Schema.struct({
+  /**
+   * @type {API.Reader<API.Link>}
+   */
+  get ran() {
+    return invocation.link()
+  },
+  out: Schema.variant({
+    ok: Schema.unknown(),
+    error: Schema.unknown(),
+  }),
+  fx: effects,
+})
+
+const task = Schema.struct({
+  run: instruction.link(),
+  meta: Schema.dictionary({
+    key: Schema.string(),
+    value: Schema.unknown(),
+  }),
+  prf: Schema.unknown().link().array(),
+
+  cause: receipt.link().optional(),
+})
+
+const auth = Schema.struct({
+  scope: Schema.unknown().link().array(),
+  s: Schema.unknown(),
+})
+
+const invocation = Schema.struct({
+  task,
+  auth: auth.link(),
+})
+
+const view = invocation.toIPLDView({
+  link: parseLink('bakfaa'),
+  store: new Map(),
+})
+
+const auth1 = auth.toIPLDBuilder({
+  scope: [parseLink('bakfaa')],
+  s: new Uint8Array(),
+})
+
+const demo = async () => {
+  invocation.toIPLDBuilder({
+    auth: (await auth1.buildIPLDView()).link(),
+    task: await task
+      .toIPLDBuilder({
+        run: parseLink('bakfaa'),
+        meta: {},
+        prf: [parseLink('bakfaa')],
+      })
+      .buildIPLDView(),
+  })
+}
diff --git a/packages/interface/src/lib.ts b/packages/interface/src/lib.ts
index 12c840e6..17b47f37 100644
--- a/packages/interface/src/lib.ts
+++ b/packages/interface/src/lib.ts
@@ -474,6 +474,43 @@ export interface InstructionModel<
   nnc: string
 }
 
+/**
+ * View over an {@link InstructionModel} DAG, providing some sugar for the API.
+ */
+export interface Instruction<
+  Op extends Ability = Ability,
+  URI extends Resource = Resource,
+  Input extends Record<string, unknown> = Record<string, unknown>
+> extends InstructionModel<Op, URI, Input>,
+    IPLDView<InstructionModel<Op, URI, Input>> {
+  readonly nonce: string
+}
+
+export interface TaskModel<Run extends InstructionModel = InstructionModel> {
+  run: Link<Run>
+  meta: Meta
+  prf: UCANLink[]
+
+  cause?: Link<ReceiptModel>
+}
+
+export interface Task<Run extends InstructionModel = InstructionModel>
+  extends TaskModel<Run> {
+  instruction: Instruction<Run['op'], Run['rsc'], Run['input']> | Link<Run>
+
+  readonly proofs: Proof[]
+}
+
+export interface InvocationModel {
+  task: TaskModel
+  auth: Link<AuthorizationModel>
+}
+
+export interface AuthorizationModel<Alg extends SigAlg = SigAlg> {
+  scope: Link[]
+  s: Signature<this['scope'], Alg>
+}
+
 /**
  * Defines result type as per invocation spec
  *