The open protocol for AI-native engineering.
Every prompt, model invocation and cost event becomes a structured Runtime Context Protocol event that can be searched, replayed and understood — versioned, vendor neutral, and open.
Without a protocol, every AI session disappears the moment it ends.
Terminal scrollback fades, context windows reset, and the reasoning behind a change is gone by the next standup. Every session starts the same way — what happens next is what RCP changes.
An engineer asks the agent to make a change — then the paths diverge.
- Response
The agent edits code and replies in the terminal.
- Lost
The session closes. Reasoning, context and cost all disappear.
- Engineering Event
The interaction is captured as a structured RCP event.
- Timeline
Runtime ingests the event into a searchable session timeline.
- Replay
Reconstruct exactly what happened, in the order it happened.
- Search
Query across every session, repository and model.
- Knowledge
Answers and insight, sourced from real engineering history.
One protocol, the whole platform.
Everything Runtime does is built on the same stream of RCP events.
- 01
AI Clients
Claude Code, Codex CLI and Cursor (Coming Soon) — every client that emits RCP events.
- 02
Runtime Context Protocol
A versioned, open event envelope: session, model invocation, completion and cost events today — tool, file and git events on the roadmap.
- 03
Runtime Platform
Ingests, stores and indexes every RCP event into a searchable engineering timeline.
- 04
Replay
Reconstructs any session from its RCP events, in the order they happened.
- 05
Ask Runtime
Answers questions about your engineering history, sourced from RCP events.
- 06
Teams & Governance
Roles, shared budgets and spend controls, all built on the same event stream.
Every event type in RCP.
Session and cost events are live in Runtime today. Tool, file, git, testing and search events are defined in the schema and on the roadmap. Expand any event to see its shape.
Emitted the moment a connected CLI process spawns your AI tool.
{ "pid": 42391, "cwd": "~/runtime-api", "tool": "claude" }Emitted when the wrapped process exits, with its exit code.
{ "exitCode": 0, "tool": "claude" }Will mark a session as idle without ending it.
{ "reason": "idle_timeout" }Emitted by the gateway proxy when a request to a model provider begins.
{ "model": "claude-sonnet-5", "provider": "anthropic" }Emitted when the provider finishes responding, before token accounting.
{ "model": "claude-sonnet-5", "durationMs": 5820 }Marks the start of a full completion, which may span multiple model invocations.
{ "requestId": "req_71ac…" }Marks the end of a completion, immediately before cost is recorded.
{ "requestId": "req_71ac…", "inputTokens": 27300, "outputTokens": 187 }Will mark the start of an extended-thinking or reasoning pass.
{ "model": "claude-sonnet-5" }Emitted by the gateway proxy once a request finishes — the same event that powers Billing and Ask Runtime cost answers.
{ "cost": 0.04, "currency": "USD", "model": "claude-sonnet-5", "provider": "anthropic" }Internal gateway routing event, not yet surfaced in the public event stream.
{ "provider": "anthropic", "cacheHit": false }Will capture every tool call an agent makes (read, edit, bash, …).
{ "tool": "edit", "target": "src/wallet/credits.ts" }Will capture each file an agent changes during a session.
{ "path": "src/wallet/credits.ts" }Will link a session to the commit it produced.
{ "sha": "e4f5g6h", "branch": "main" }Will link test runs an agent triggered back to the session.
{ "suite": "auth", "passed": 12, "failed": 0 }Will capture codebase searches an agent runs while working.
{ "query": "credits ledger", "results": 6 }
Not a logging format. A protocol.
RCP aims to become the common language for AI-assisted engineering — the way OpenTelemetry became the common language for application telemetry. Runtime is the reference implementation, but the protocol is designed to outlive any one product.
Vendor neutral
RCP is not tied to one model provider or one AI coding tool.
Extensible
New event types can be added to the schema without breaking old consumers.
Versioned
Every event carries a protocol version, currently 1.0.0-alpha.
Searchable
Structured events index cleanly, unlike free-text chat transcripts.
Replayable
A complete event stream can be reconstructed into a trace.
Built for AI-native development
Designed around how AI tools actually work: sessions, invocations, cost.
Build on an open protocol.
Read the specification, explore the event taxonomy, or start capturing RCP events from your own AI-assisted engineering sessions today.