Platform · Module
Kernel Action Bus
The single governed entry point for every state change and side effect
The Kernel Action Bus is the one path every write takes, whether it comes from a person, an agent, an API, an MCP client or WhatsApp. It validates, checks policy and budget, routes approvals, executes with an outbox and records audit, cost and trace.
Every write is an Action
In One3, nothing changes state except through a typed Action. Each Action is registered from an app's manifest with an id, version, input and output schema, risk tier, permissions, idempotency flag, side effects, reversibility class, emitted events, rate limit, cost hint, an AI-readable description and examples.
The invocation pipeline
When anything calls an Action, the bus runs the same steps: schema validation, then tenant and actor resolution, entitlement, licence, permission and scope, segregation of duties, policy and DoA, budget, connector health, approval, execution, outbox and audit. A call from the UI, the REST API, an MCP client, Copilot or a Digital Employee produces the same audit record. Errors are typed, such as NOT_ENTITLED, PENDING_APPROVAL, BUDGET_EXCEEDED, CONNECTOR_UNHEALTHY or KILL_SWITCH_ACTIVE, so every client handles them the same way.
Safe by construction
- Idempotency keys with request hash and stored response prevent double execution.
- Reversibility classes and undo or compensation tokens are shown with honest UI wording.
- A transactional outbox publishes CloudEvents-aligned events.
- Durable approval waits survive restarts and resume on a decision.
- Budgets are consumed atomically in the Action transaction, with block, require-approval or notify outcomes.
- Connector health gates stop agent Actions that rely on stale connector data.
Generated, not hand-written
From the registry, One3 generates REST and OpenAPI definitions, MCP tools, a TypeScript client, views and tests. That keeps every surface in step.
Later waves
Wave 2 adds per-tenant and per-actor rate limits with priority classes, per-object Action history with reverse buttons, a bulk invocation API, kill-switch enforcement, decision and outcome linkage, and Action versioning with deprecation windows. Sagas for multi-step compensation and agreement checks follow in Wave 3, and cross-company Actions with external agents in Wave 6.
Features
What Kernel Action Bus includes
Action registry
Actions from app manifests with schema, risk tier, permissions, reversibility, events, rate limit, cost hint and AI description. W0.
One invocation pipeline
Validation, actor, entitlement, licence, permission, SoD, policy and DoA, budget, approval, execute, outbox and audit. W0.
Idempotency keys
Request hash, stored response and expiry so retries never double-execute. W0.
Reversibility and undo
Reversibility classes with undo or compensation tokens and honest UI wording. W0.
Transactional outbox
Events published through an outbox with a CloudEvents-aligned envelope. W0.
Typed errors
A shared error vocabulary from NOT_ENTITLED to KILL_SWITCH_ACTIVE for every client. W0.
Durable approval wait
Approval pauses survive restarts and resume on decision. W0.
Code generation
REST/OpenAPI, MCP tools, TypeScript client, views and tests generated from the registry. W0.
Cost and trace linkage
Trace id, cost, goal and budget recorded on every Action log entry. W0.
Budgets
Atomic budget consumption with block, require-approval or notify outcomes. W1.
Connector health gate
Agent Actions using connector data are restricted when health is degraded. W1.
Rate limits and priority classes
Per-tenant and per-actor token buckets; interactive ahead of approvals ahead of batch. W2.
Action history with reverse
Who changed what, through which channel, with reverse or compensate buttons. W1–W2.
Bulk API and versioning
Batched invocation with per-item results; versioned Actions with deprecation windows. W2.
Workflow
From call to audit
- 1
A caller invokes an Action with an idempotency key.
- 2
The bus validates input and resolves tenant and actor.
- 3
Entitlement, permission, SoD, DoA, budget and connector health are checked.
- 4
R3 or above pauses for approval; otherwise it executes.
- 5
The transaction writes data and the outbox event, then audit, cost and trace are recorded.
AI
AI skills and Digital Employees
Blast-radius grouping
After an agent incident, groups affected Actions and proposes bulk reverse or compensate steps for approval. W2.
AI-readable Action descriptions
Each Action's description and examples feed MCP tools and Copilot, so agents call the same contract people do.
Digital Employees that use this module
- AI Agent Governance Auditor
They act through the same governed Actions as people; risky steps wait for approval.
Frequently asked questions
Why route every write through one bus?
So that people, agents, APIs and channels all get the same permission, policy, approval, audit and cost handling. There is no side door.
Can an agent's Action be undone?
It depends on the Action's reversibility class. Reversible Actions carry undo tokens; others carry compensation steps; irreversible ones are labelled honestly and usually need approval.
Is the Action Bus sold separately?
No. It is a kernel service included in the Platform for every subscription.
See Kernel Action Bus in your workflow
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