Turn non-deterministic model output into deterministic execution. expresso makes rules, permissions, identity, and recovery explicit before an agent acts.
The provider completes this refund, but its reply never returns. Run recovery to watch expresso reconcile the outcome instead of sending it twice.
refund.expresso
interactive demo
Customercus_3841
Amount$48.00
Action IDrefund_01JQ
01
Observe
Refund request preserved exactly as the agent produced it.
02
Validate
Customer, amount, reason and policy checked before action.
03
Plan
One stable identity assigned to this refund.
04
Act
Provider accepted the request, but its response was lost.
05
Recover
Provider history reconciled using the same refund identity.
06
Complete
One refund recorded. No second reversal was attempted.
ReadyRun recovery to follow the action.
The controlled path
Three steps from uncertainty to action.
I
Observe
Accept information from an AI, a person, a sensor or an API. Preserve exactly what the workflow received.
II
Validate
Apply clear, deterministic rules before uncertain information can influence an action.
III
Action
Make a real-world change with explicit permission, a stable identity and a defined recovery path.
Agents can reason freely. Consequential actions follow a path expresso can verify.
Consequential work
Where agents need more than a prompt.
Prompts guide reasoning. expresso puts enforceable boundaries around what happens next.
01
Trigger outreach
Campaigns, sales outreach, notices, follow-ups and support.
02
Move money
Charges, refunds, payouts, invoices, credits and approvals.
03
Deploy code
Merges, deployments, configuration, migrations and rollback.
04
Control access
Accounts, roles, credentials, revocation and offboarding.
05
Update records
Customer, financial, operational and CRM data across systems.
06
Commit resources
Orders, renewals, inventory, appointments and scheduling.
A precise guarantee
The guarantee isnarrow on purpose.
expresso proves the path from uncertain information to an external action. It does not pretend to know whether the information is true or the decision is wise.
Inside the boundary
The runtime can prove
enforced
01
Declared flow
Only named observations can influence the action.
02
Checks before change
Required conditions resolve before execution.
03
Stable identity
Every attempt refers to the same real-world intent.
04
Evidence-backed recovery
Unclear outcomes reconcile against provider state.
scopeedge
Beyond the boundary
Judgment remains yours
visible
Truth
Is the observation accurate?
Wisdom
Is this the action you intend to take?
Policy
Does your rule cover the case that actually occurred?
Start in the stack you already use
Add expresso to any project.
Use the plugin in Codex, or initialize the CLI for Claude Code and any other agent. Every path uses the same language, verifier and runtime.
$npx @technodotventures/expresso init
One runtime. Any model. Node.js 22+.
Install for Codex
Add the public expresso marketplace, then install the authoring plugin directly in Codex.
How expresso fits, what it enforces and what stays in your control.
01What is expresso?+
expresso is a language and runtime for the consequential parts of an agent workflow. It turns uncertain model output into explicit observations, checks, permissions, actions and recovery rules before an external system is allowed to change.
02Where does it fit in my existing stack?+
Between your agent and the systems it can change. Keep your model, framework, application code and provider SDKs; use expresso for the path from model output to consequential action.
03Does it work with Codex, Claude Code and other agents?+
Yes. Codex has a dedicated authoring plugin. Claude Code and other coding agents can use the same language, verifier and runtime through the expresso CLI.
04Do I need a plugin?+
No. The CLI and runtime are the shared foundation. The Codex plugin is a thin integration that teaches Codex how to create, review and check expresso workflows with less setup.
05Do I need to replace my agent framework?+
No. expresso is designed to sit beside the stack you already use. Adopt it only where an agent crosses a boundary into payments, outreach, deployment, access, records or other consequential work.
06What does expresso enforce?+
Explicit validation before action, stable identity for each action, declared authority, runtime permission checks and provider-backed recovery. The workflow is inspectable before it runs.
07What does expresso not decide?+
It does not decide whether an observation is true, an action is wise or your business policy is complete. It makes those assumptions visible and enforces the boundaries you declare.
08What happens when a provider response is lost?+
The runtime keeps the same action identity and follows the recovery contract you defined: retry safely, reconcile against provider history or stop for review. It does not invent a new action and hope.
09How are permissions and credentials handled?+
Workflows declare the grants they require. A trusted host grants and re-checks that authority at runtime, while provider credentials remain outside model output and expresso source.
10Can I use my existing APIs and providers?+
Yes. Connect existing systems through typed provider operations and explicit recovery contracts. Your provider remains the source of truth; expresso controls how an agent is allowed to reach it.
