@tangle-network/tcloud-agent

Agent run-loop primitive for Tangle AI Cloud. Runs an AgentProfile against a brief, evaluates criterion gates after each iteration, respects budget caps, and streams events. Use it when you need a run-until-verified loop over the Tangle sandbox bridge — without rebuilding the iteration / verification / budget plumbing yourself.

Why

Most agent libraries either (a) ship a giant framework with opinions baked in (LangChain, Claude Agent SDK), or (b) give you a streaming-chat primitive and leave the loop to you (Vercel AI SDK). tcloud-agent is the third thing: a single tight run-loop that knows about iterations, verification gates, and budget — and nothing else. You bring the profile, the brief, and the criteria; it handles the loop and the streaming.

It composes the Tangle TCloud SDK and runs over the sandbox-harness BridgeSession, so every iteration goes through Tangle routing with full control over operators, models, and policies.

Table of contents

• Install
• Quick start
• Concepts
  • AgentRunOptions
  • AgentRunCriterion
  • AgentBudget
  • AgentRunResult and verdicts
  • Streaming events
• Examples
  • Minimal run()
  • Stream events to stdout
  • Cataloged profile + custom criteria
  • Budget-bounded loop
  • Workspace-bound run
  • Inline AgentProfile from @tangle-network/sandbox
  • Resume a session across calls
  • TangleToolProvider for Pi
• API reference
• Architecture
• Comparison vs alternatives
• FAQ
• Contributing
• License

Install

pnpm add @tangle-network/tcloud-agent @tangle-network/tcloud
# npm install / yarn add also work

Peer dependencies (only needed for the Pi-extension entry point — skip if you're driving the agent from a server / CLI):

pnpm add -D @mariozechner/pi-coding-agent @mariozechner/pi-tui

Requires Node 20+.

Quick start

import { TCloud } from '@tangle-network/tcloud'
import { agent } from '@tangle-network/tcloud-agent'

const client = new TCloud({ apiKey: process.env.TCLOUD_API_KEY! })

const result = await agent(client, {
  profile: 'sf-proposer',
  brief: 'Scaffold a Vite + React package and confirm pnpm build passes.',
  criteria: [
    { name: 'build-passes', check: async (ctx) => ({ ok: ctx.lastMessage.includes('pnpm build: ok') }) },
  ],
  budget: { iterations: 5, wallSec: 600, usd: 1 },
}).run()

console.log(result.verdict)        // 'verified' | 'blocked' | 'budget-exhausted' | 'error'
console.log(result.iterations)     // how many turns it took
console.log(result.usd)            // approximate spend (null if upstream didn't report usage)
console.log(result.transcript)     // full conversation

Five lines of config, one await. The loop runs until every criterion returns { ok: true }, the budget exhausts, or an error escapes the bridge.

Concepts

AgentRunOptions

| Field | Type | Description | |---|---|---| | profile | AgentProfile \| string | Inline profile object (from @tangle-network/sandbox) or a cataloged profile id resolved server-side | | brief | string | First user turn — what the agent is being asked to do | | criteria? | AgentRunCriterion[] | Completion gates evaluated after each iteration. Empty/undefined ⇒ first reply verifies. | | budget? | AgentBudget | { iterations?, wallSec?, usd? } — first breach exits with budget-exhausted | | resume? | string | Pass-through to BridgeOptions.resume for session continuity | | workspace? | { dir: string } | Bind a local directory; surfaced on AgentRunContext.workspaceDir and appended to the brief | | unlock? | string | BridgeOptions.unlock. Falls back to process.env.BRIDGE_UNLOCK. | | bridgeUrl? | string | BYOB cli-bridge URL (forwarded to BridgeOptions.bridgeUrl) | | bridgeBearer? | string | BYOB cli-bridge bearer token | | stream? | boolean | false to disable SSE — each iteration calls chat() non-streaming, emits one message.delta per turn. Default true. |

AgentRunCriterion

interface AgentRunCriterion {
  name: string  // stable id; surfaced on result.blockedBy if it fails
  check: (ctx: AgentRunContext) => Promise<{ ok: boolean; reason?: string }> | { ok: boolean; reason?: string }
}

Criteria are checked in order after each assistant turn. If any criterion returns ok: false, the loop continues to the next iteration with the criterion's reason appended as a follow-up user message. When all criteria pass, verdict is verified.

Empty criteria ⇒ the first assistant reply auto-verifies.

AgentBudget

interface AgentBudget {
  iterations?: number  // max loop iterations
  wallSec?: number     // wall-clock cap; first breach exits
  usd?: number         // best-effort spend cap (relies on ChatCompletion.usage)
}

Any field can be omitted. The first breach wins; verdict is budget-exhausted.

AgentRunResult and verdicts

interface AgentRunResult {
  verdict: 'verified' | 'blocked' | 'budget-exhausted' | 'error'
  iterations: number
  wallMs: number
  usd: number | null         // null when no usage was reported
  transcript: { role: 'user' | 'assistant' | 'system'; content: string }[]
  blockedBy?: string         // criterion.name when verdict === 'blocked'
  error?: string             // captured message when verdict === 'error'
}

run() never throws — bridge failures land as verdict: 'error' with the message captured. Branch on verdict, not on try/catch.

Streaming events

stream() emits AgentEvents in this order per iteration:

iteration.start
  → message.delta*           (zero or more, may interleave with tool events)
  → tool.call.start*
  → tool.call.result*
  → iteration.complete
  → criterion.check*         (one per evaluated criterion)
... next iteration, or:
verdict                       (terminal — same payload as run() returns)

tool.call.* events are reserved in the union and only fire when the upstream bridge surfaces tool parts via non-standard delta fields. Most runs see iteration.* + message.delta + criterion.check + verdict only.

Examples

Example 1: Minimal run()

import { TCloud } from '@tangle-network/tcloud'
import { agent } from '@tangle-network/tcloud-agent'

const client = new TCloud({ apiKey: process.env.TCLOUD_API_KEY! })
const result = await agent(client, {
  profile: 'sf-proposer',
  brief: 'Reply with the literal text "ok".',
}).run()

console.log(result.verdict, '·', result.iterations, 'iter')

No criteria, no budget — first reply ⇒ verdict verified. Useful for smoke tests.

Example 2: Stream events to stdout

for await (const ev of agent(client, opts).stream()) {
  switch (ev.type) {
    case 'iteration.start':
      process.stdout.write(`\n[iter ${ev.iteration}] `)
      break
    case 'message.delta':
      process.stdout.write(ev.text)
      break
    case 'criterion.check':
      process.stdout.write(`\n  ${ev.ok ? '✓' : '✗'} ${ev.name}${ev.reason ? ` — ${ev.reason}` : ''}\n`)
      break
    case 'verdict':
      process.stdout.write(`\n[verdict: ${ev.verdict}, ${ev.iterations} iter, $${ev.usd ?? '?'}]\n`)
      break
  }
}

Live observability into the loop — exactly what run() consumes internally.

Example 3: Cataloged profile + custom criteria

const result = await agent(client, {
  profile: 'sf-proposer',
  brief: 'Scaffold an agent-runtime bundle for a music-producer agent.',
  criteria: [
    {
      name: 'manifest-valid',
      check: async (ctx) => {
        const m = ctx.lastMessage.match(/^\{[\s\S]+\}$/m)
        try {
          JSON.parse(m?.[0] ?? '')
          return { ok: true }
        } catch (err) {
          return { ok: false, reason: `manifest is not valid JSON: ${(err as Error).message}` }
        }
      },
    },
    {
      name: 'has-frontmatter',
      check: async (ctx) => ({
        ok: /^---\n[\s\S]+?\n---/m.test(ctx.lastMessage),
        reason: 'system-prompt.md frontmatter missing',
      }),
    },
  ],
}).run()

if (result.verdict === 'blocked') {
  console.error(`blocked by: ${result.blockedBy}`)
}

When a criterion fails, the loop appends Previous attempt failed: <reason> as the next user turn — the agent gets to fix it without you re-prompting.

Example 4: Budget-bounded loop

const result = await agent(client, {
  profile: 'sf-proposer',
  brief: 'Generate 50 manifest variants and report which pass schema validation.',
  budget: {
    iterations: 8,    // hard cap on loop count
    wallSec: 300,     // 5 minutes wall clock
    usd: 2,           // soft cap — relies on usage reporting
  },
}).run()

if (result.verdict === 'budget-exhausted') {
  console.warn(`stopped at ${result.iterations} iter / ${result.wallMs}ms / $${result.usd}`)
}

Caps are checked at iteration boundaries. First breach wins — useful for cron jobs and CI gates.

Example 5: Workspace-bound run

import { mkdtempSync } from 'node:fs'
import { tmpdir } from 'node:os'
import { join } from 'node:path'

const workspace = mkdtempSync(join(tmpdir(), 'agent-run-'))

const result = await agent(client, {
  profile: 'sf-proposer',
  brief: 'Write the manifest into manifest.json under the workspace dir.',
  workspace: { dir: workspace },
  criteria: [
    {
      name: 'file-written',
      check: async (ctx) => {
        const { existsSync } = await import('node:fs')
        return {
          ok: existsSync(`${ctx.workspaceDir}/manifest.json`),
          reason: 'manifest.json missing in workspace',
        }
      },
    },
  ],
}).run()

The workspace path is appended to the brief so the agent knows where to cd, and surfaces on ctx.workspaceDir for filesystem-aware criteria. Pair with the sandbox-harness file write tool.

Example 6: Inline AgentProfile

import type { AgentProfile } from '@tangle-network/sandbox'

const profile: AgentProfile = {
  name: 'one-off-reviewer',
  systemPrompt: 'You review TypeScript diffs and report PASS or FAIL with a one-line justification.',
  capabilities: { /* ... */ },
}

const result = await agent(client, {
  profile,                            // inline, not cataloged
  brief: 'Review this diff:\n```diff\n... \n```',
}).run()

Drop in any AgentProfile object directly — no server-side catalog lookup, no extra round-trip.

Example 7: Resume a session across calls

const first = await agent(client, {
  profile: 'sf-proposer',
  brief: 'Plan the family scaffold; reply with the plan only.',
}).run()

const second = await agent(client, {
  profile: 'sf-proposer',
  brief: 'Implement the plan you just produced.',
  resume: first.transcript[0]?.content?.startsWith('session:') ? /* extract id */ '' : undefined,
}).run()

resume forwards to BridgeOptions.resume — when the bridge supports it, the second agent starts on top of the first agent's session state.

Example 8: TangleToolProvider for Pi

import { TangleToolProvider, type CapabilityHandler } from '@tangle-network/tcloud-agent'

const handlers: CapabilityHandler[] = [
  {
    name: 'tangle_search',
    description: 'Search the Tangle docs',
    parameters: { query: { type: 'string' } },
    execute: async ({ query }) => ({
      results: await fetch(`https://docs.tangle.tools/search?q=${encodeURIComponent(query as string)}`).then(r => r.text()),
    }),
  },
]

const provider = new TangleToolProvider({ handlers })
const tools = provider.toOpenAITools()       // hand to your chat call
await provider.invoke('tangle_search', { query: 'sandbox bridge' })

Use directly with any OpenAI-compatible chat surface, or register the package as a Pi extension via the ./pi-extension subpath.

API reference

agent(client, options) / new Agent(client, options)

Build a runnable agent. Identical surface — function form is just new Agent(...).

| Method | Signature | Description | |---|---|---| | run | (): Promise<AgentRunResult> | Run to completion. Never throws — failures land on result.verdict === 'error'. | | stream | (): AsyncIterable<AgentEvent> | Event stream. Final event is always { type: 'verdict', ... }. |

run() is a thin consumer of stream() — the loop logic lives once.

Re-exports

Agent, agent, all AgentRun* types, AgentEvent, TextPart, ToolPart, ToolState, TangleToolProvider, CapabilityHandler, ToolResult.

Subpath: @tangle-network/tcloud-agent/pi-extension

Drop-in Pi extension that registers the agent runner + TangleToolProvider into a Pi config. Peer-installable; requires @mariozechner/pi-coding-agent and @mariozechner/pi-tui.

import tcloudExtension from '@tangle-network/tcloud-agent/pi-extension'

export default {
  extensions: [tcloudExtension],
}

Architecture

                ┌─────────────────────────────┐
                │  Agent  /  agent()          │
                │  - iteration counter        │
                │  - criteria evaluation      │
                │  - budget tracker           │
                │  - event emitter            │
                └──┬───────────────────┬──────┘
                   │                   │
                   ▼                   ▼
        ┌──────────────────┐   ┌──────────────────┐
        │  TCloudClient    │   │  Sandbox Bridge  │
        │  .bridge(...)    │──▶│  BridgeSession   │
        └──────────────────┘   │  (chat / stream) │
                               └────────┬─────────┘
                                        │
                                        ▼
                                ┌────────────────┐
                                │ Tangle Router  │
                                │  + Operators   │
                                └────────────────┘

The runner owns the loop — it does not own the model, the operator, or the wallet. Those live in the TCloud SDK's bridge() surface. Want operator rotation? Use TCloudClient.rotating() — that's a client-level rotation strategy, separate from the agent loop.

Comparison vs alternatives

| | tcloud-agent | LangChain agent | Vercel AI SDK | Claude Agent SDK | |---|---|---|---|---| | Loop primitive | ✅ minimal | heavy framework | none (DIY loop) | subprocess runtime | | Streaming events | ✅ typed union | yes | yes | yes | | Criterion gates | ✅ first-class | manual | manual | manual | | Budget caps | ✅ first-class | manual | manual | manual | | Workspace binding | ✅ first-class | manual | manual | implicit | | Verdict shape | typed enum | string | string | string | | Browser-runnable | partial (Node 20+ today) | yes | ✅ | ❌ subprocess | | Tangle routing / sandbox | ✅ native | adapter | adapter | n/a |

Use tcloud-agent when: you want a small, opinionated run-loop primitive over Tangle infrastructure with built-in criterion + budget gates. Skip it when: you only need a single chat call (use the TCloud SDK directly) or you want a full agent framework with planners / memory / tool registries (LangChain or Mastra).

FAQ

Q: How does this differ from @tangle-network/tcloud? A: TCloud is the SDK — single chat / completion / embedding calls, plus .bridge() for sandbox-harness sessions and .rotating() for operator rotation. tcloud-agent adds the iteration / verification / budget loop on top. Use the SDK directly for one-shot calls; use tcloud-agent when you need run-until-verified semantics.

Q: What is "the bridge"? A: TCloudClient.bridge(options) opens a BridgeSession that proxies chat traffic through the Tangle sandbox-harness. The agent runs each iteration through that bridge so requests inherit Tangle routing, attestation, and policy enforcement.

Q: Can I use this without the bridge / sandbox? A: The runner depends on client.bridge(...). If you want a plain ChatCompletions agent, the loop logic itself is small — copy it and back it with client.chat() directly.

Q: Are tool calls supported? A: The event union reserves tool.call.* events. Today they only fire when the bridge surfaces tool parts via non-standard delta fields. Standard OpenAI-shaped tool-call events flow through message.delta until the upstream bridge protocol exposes them as separate parts.

Contributing

Code lives in tangle-network/tcloud under packages/tcloud-agent/.

git clone https://github.com/tangle-network/tcloud
cd tcloud
pnpm install
pnpm --filter @tangle-network/tcloud-agent build
pnpm --filter @tangle-network/tcloud-agent test

License

Dual-licensed under either:

• MIT License
• Apache License 2.0

at your option.