Series A · 2026 · Bordeaux

# Calmer infrastructure for the agents already running your business.

Halcyon is a runtime for long-running AI agents that need stable identity, predictable cost, and an audit trail you can hand to legal. We replace the YAML scaffolding teams keep rebuilding from scratch.

runtime · live

#### research-agent / tier-3

healthy · 7d 14h uptime

spend / 24h
$47.18USD
tasks / 24h
1,284ok
audit · last entry

`04:12:09` · ticket `PRD-4731` dispatched to research-agent/tier-3 by quentin.albrecht. Resolved in 41.7s.

02 · platform

Five primitives. No agent framework lock-in. Bring your own model, your own tools, your own sandbox — keep the runtime, the policies, and the bill in one place.

## The runtime is the boring part. We're obsessed with the boring part.

01 · identity

### Stable identities, not session tokens.

Every agent gets a long-lived identity with revocable credentials, scoped policies, and a portable memory layer that survives model swaps. Rotate keys without re-onboarding the agent.

// stable across model swaps
agent.identity = {
id: "agent_q7_research",
policy: "tier-3:read-only",
memory: halcyon.memory("q7"),
};
02 · spend

### One bill. One cap. One alarm.

Set budgets per agent, per workspace, per provider. Halcyon throttles before the bill becomes a Slack post-mortem.

$0.018avg / task
03 · audit

### An audit log shaped like an audit log.

Append-only. Cryptographically chained. Streams to your SIEM. Every tool call, every prompt, every model swap, every refund — in one place legal can actually subpoena.

04 · sandbox

### Real sandboxes.

Firecracker microVMs per task. Boots in 110ms.

05 · routing

### Model-agnostic routing.

Cheapest model that passes your eval. Updated nightly.

06 · ergonomics

### Three SDKs. Two CLIs.

Python, TypeScript, Go. `halcyon` & `hl`.

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## Less duct tape between the model and the bill.

14-day evaluation, then choose pay-as-you-go or annual. We'll send a real engineer for setup. No SDR funnel.