MECHANISM · INTERFACES · CORE

Client–Server Protocol

Expose the harness loop, sessions, events, approvals, and configuration to terminal, IDE, desktop, or automation clients through a stable transport boundary.

2 lessons5 agent snapshots0 experiments

interfacesclient-server-protocolproblem → policy → evidence

L0Intuitionpartial

L1Buildmissing

L2Engineeringpartial

L3Architecturepartial

L4Researchpartial

DEPENDENCY GRAPH · READER PATH

What feeds it, and what does it unlock?

Arrows show learning and design dependencies, not runtime data flow. Follow any node to continue through the Atlas.

Prerequisites

agent-loopAgent Loop event-streamEvent Stream

client-server-protocolClient–Server ProtocolCurrent research boundary

UnlocksNo dependents yet

Bilingual deep dive missing

Expose the harness loop, sessions, events, approvals, and configuration to terminal, IDE, desktop, or automation clients through a stable transport boundary.

The structured record is in the Atlas, but the L0–L4 article has not passed content review.

AGENT MAPPING · EVIDENCE ONLY

Snapshot implementations

An implementation enters the map only when both a snapshot and claims exist; unknowns remain visible.

UNKNOWN · EVIDENCE GAPClaude Code

No implementation currently clears the Snapshot + Claim threshold; this is not a claim that the product lacks the capability.

Inspect coverage boundary →

PARTIALCodex

1 evidence-backed claim.

codex-2026-08-10-app-server →

PARTIALGrok Build

1 evidence-backed claim.

grok-build-2026-08-10-source →

SUBSTANTIALOpenCode

1 evidence-backed claim.

opencode-2026-08-10-source →

PARTIALPi

1 evidence-backed claim.

pi-2026-08-10-rpc →

PARTIALReasonix

1 evidence-backed claim.

reasonix-2026-08-10-acp →

UNKNOWN · EVIDENCE GAPReference Harness

No implementation currently clears the Snapshot + Claim threshold; this is not a claim that the product lacks the capability.

Inspect coverage boundary →

source + sourcereviewed

codex-source-app-server

The pinned Codex App Server accepts JSON-RPC requests and notifications over selectable stdio, Unix-socket, or WebSocket transports and dispatches typed requests through dedicated processors.

Agent: Codex
Snapshot: codex-2026-08-10-app-server
Reviewed: 2026-08-10

Snapshot claim →source · AppServerTransport startup and JSONRPCMessage dispatch ↗source · process_request and typed request processors ↗

sourcereviewed

grok-build-source-acp-interface

Grok Build's pinned ACP library implements line-oriented JSON-RPC transport and normalization, and the shell projects Agent activity into ACP session updates for editor or process clients.

Agent: Grok Build
Snapshot: grok-build-2026-08-10-source
Reviewed: 2026-08-10

Snapshot claim →source · ACP channel, message, normalization, and line-reader modules ↗

source + sourcereviewed

opencode-source-client-server

OpenCode's pinned source exposes a headless HTTP server, while the terminal UI can use an embedded worker and RPC-forward global server events rather than owning a separate Agent core.

Agent: OpenCode
Snapshot: opencode-2026-08-10-source
Reviewed: 2026-08-10

Snapshot claim →source · HTTP application and event routes ↗source · embedded fetch and global event forwarding ↗

source + sourcereviewed

pi-source-rpc-mode

Pi RPC mode accepts typed commands as LF-delimited JSON on stdin and emits responses plus agent events as LF-delimited JSON on stdout, including controls for prompting, steering, sessions, compaction, retry, models, and tools.

Agent: Pi
Snapshot: pi-2026-08-10-rpc
Reviewed: 2026-08-10

Snapshot claim →source · RpcCommand; RpcResponse; RPC events ↗source · RPC command dispatch and JSONL output ↗

source + sourcereviewed

reasonix-source-acp

Reasonix ACP uses an NDJSON JSON-RPC 2.0 connection over stdin/stdout, runs requests and notifications concurrently, maps engine events to session updates, and forwards gated tool decisions as client permission requests.

Agent: Reasonix
Snapshot: reasonix-2026-08-10-acp
Reviewed: 2026-08-10

Snapshot claim →source · Conn; Serve; JSON-RPC framing ↗source · updateSink; requestPermission ↗

EXPERIMENTS · EXERCISES

What has actually been tested?

Formal experiments are separate from course exercises. Exercises can validate the reference implementation but cannot replace Native evidence from a real agent.

Formal experiment · not registered

No experiment record means untested, not passed. The course checks below cover only the deterministic reference harness.

s01-agent-loopobserve

Verify the Golden Trace

The committed JSONL exactly matches a real demo run and passes the trace schema.

python3 -m curriculum.golden verify s01-agent-loop

s01-agent-loopmodify

Preserve loop invariants

A completed run keeps contiguous sequence numbers and ends with session.stop.

python3 -m unittest curriculum.tests.test_vertical_slice.VerticalSliceTests.test_s01_minimal_loop -v

s02-events-streamingobserve

Verify the streaming trace

Three deltas produce three ordered events and the last is explicitly final.

python3 -m curriculum.golden verify s02-events-streaming

s02-events-streamingmodify

Test the streaming message contract

Deltas remain replayable without polluting the next-turn message history.

python3 -m unittest curriculum.tests.test_vertical_slice.VerticalSliceTests.test_s02_streaming_becomes_events -v

OPEN QUESTIONS · L4

Which lifecycle events and approval semantics are portable across clients?

How should protocol compatibility be versioned independently of product releases?

Where should session authority live when multiple clients can reconnect?

What feeds it, and what does it unlock?

Snapshot implementations

codex-source-app-server

grok-build-source-acp-interface

opencode-source-client-server

pi-source-rpc-mode

reasonix-source-acp

Move from explanation into code and traces.

The Minimal Agent Loop

Streaming and Events

What has actually been tested?