SynAP — the Synaptic Agent Protocol

A semantic control plane for inter-agent communication — toward a narrow waist for the Internet of Agents.

Paper (v1.0, July 2026): doi.org/10.5281/zenodo.21176725 · source in paper/

SynAP defines an eleven-performative mandatory semantic floor with negotiated dialects above it (typed → embeddings → same-model latent exchange, degrading gracefully to natural language), and five wire-level control-plane mechanisms: comprehension-conditioned ACK with dialect-downgrade retransmission, delegation-depth TTL with cycle detection, context-window flow control with multi-hop budget decomposition and QoS classes, a VERIFY performative returning graded grounded verdicts, and a HANDOVER performative with admission control and dialect-encoded state transfer.

Reference implementation

pip install synap-protocol          # core: wire models + control plane (pydantic only)
pip install "synap-protocol[net]"   # + signed HTTP transport & DID identity
python -m synap_protocol.demo

Core — the wire models (datagram, eleven-performative floor, dialect ladder), the control-plane guards (TTL, cycle detection, receive windows, budget decomposition), the semantic-ACK policy with ladder-descent retransmission, and an in-memory runtime.

[net] extra — Ed25519 self-certifying DIDs, datagram signing, and a fail-closed HTTP/ASGI transport (SynapServer/SynapClient). The network surface went through the project's security cadence — audit → fix → three red-team rounds → verify. See SECURITY.md for the trust model and guarantees.

Measurement harness — synap_protocol.measure quantifies the dialect ladder's token/latency/fidelity trade-off; python examples/measure_demo.py runs an illustrative (synthetic, clearly-labeled) study. Real numbers require a live model backend.

Real captured demo output:

== 1. comprehension control: downgrade to understanding ==
   opened at d1 -> misunderstood -> re-expressed -> d0.nl [understood, score=0.96]
   receiver's proof-of-understanding: 'caller wants the Q3 revenue variance summarized by region'

== 2. delegation safety: cycles and depth on the wire ==
   cycle attempt   -> REFUSE basis=cycle
   ttl=0 attempt   -> REFUSE basis=depth-exhausted

== 3. budget soundness: over-grant rejected before the wire ==
   parent 10000tok/$2.00 -> grant 4000tok/$0.50 -> remainder 6000tok/$1.50
   over-grant 9000tok  -> REJECTED: token grant 9000 exceeds remaining 6000

PASS: all three control-plane mechanisms enforced.

Development

uv sync --extra net
uv run ruff check src tests && uv run mypy && uv run pytest

— amitpatole