AG-UI is an event-based protocol that lets AI agent backends communicate with user-facing applications. It standardizes agent events and inputs while supporting transports such as server-sent events, WebSockets, and webhooks. The catalogue add-ons help developers build integrations and applications around the protocol.
Borrowing it
Nothing to install: this file belongs to ag-ui-protocol/ag-ui. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/ag-ui-protocol/ag-ui/main/.github/skills/agui-cross-sdk-parity/SKILL.mdgit clone --depth 1 https://github.com/ag-ui-protocol/ag-uiWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/ag-ui-protocol/ag-ui/agui-cross-sdk-parity)<a href="https://agentmods.dev/skills/ag-ui-protocol/ag-ui/agui-cross-sdk-parity"><img src="https://agentmods.dev/badge/skills/ag-ui-protocol/ag-ui/agui-cross-sdk-parity/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/ag-ui-protocol/ag-ui/agui-cross-sdk-parity"><img src="https://agentmods.dev/badge/skills/ag-ui-protocol/ag-ui/agui-cross-sdk-parity.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00233 | $0.02078 |
| Opus 5.5 | $0.00093 | $0.00831 |
| Sonnet 5.5 | $0.00047 | $0.00416 |
| Haiku 4.5 | $0.00023 | $0.00208 |
Grade A, and why
agui-cross-sdk-parity scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 129 lines — stays where its author put it; the contents beside it link to each section on GitHub.
AG-UI Cross-SDK Parity
The .NET SDK implements an upstream, multi-language protocol. This skill encodes the parity process: which SDK is authoritative, where its reference and fixtures live, how to map reference concepts onto the .NET model, and how parity is guarded.
Parity Principle
- TypeScript is canonical for wire format AND client run-loop behavior. When two SDKs disagree, match TS.
- Python is types + encoder only. It has
core(types/events) and anencoder, but no client run-loop and no protobuf (sdks/python/ag_ui/hascore/andencoder/but noclient/orproto/). Use it only as a secondary check on type/JSON shape — never for run-loop or proto questions. - Upstream protocol or SDK fixes (in the TS client run-loop, or in Microsoft.Extensions.AI / Microsoft Agent Framework) sometimes need a .NET counterpart; treat the TypeScript change as the contract to match.
Where the Reference Lives
| Concern | TypeScript reference (source of truth) | .NET package it maps to |
|---|---|---|
| Event & type definitions | sdks/typescript/packages/core/src/events.ts, types.ts, event-factories.ts |
sdks/dotnet/src/AGUI.Abstractions/Events/, Messages/ |
| Client run-loop / transport | sdks/typescript/packages/client/src/run/, apply/, agent/, transform/ |
sdks/dotnet/src/AGUI.Client/ (AGUIChatClient.cs, AGUIHttpTransport.cs, EventStreamConverter.cs, ToolCallBuilder.cs) |
| SSE / JSON wire framing | sdks/typescript/packages/encoder/src/encoder.ts |
sdks/dotnet/src/AGUI.Formatting/, AGUI.Abstractions/Serialization/ |
| Protobuf wire format | sdks/typescript/packages/proto/src/proto/events.proto, types.proto, patch.proto |
sdks/dotnet/src/AGUI.Protobuf/ (ProtoEventMapper.cs, ProtoMessageMapper.cs) |
The src/ packages are AGUI.Abstractions, AGUI.Formatting, AGUI.Protobuf, AGUI.Client,
AGUI.Server; sdks/dotnet/AGENTS.md and docs/architecture.md are the canonical
description of the layout and conventions.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2mo ago First seen · 129 lines · 233 tokens per session scan A 2a82272bdb09
agui-cross-sdk-parity is a skill published in the GitHub repository ag-ui-protocol/ag-ui (16,881 stars, last pushed yesterday), licensed MIT. It adds 233 tokens to every session and 2,078 once invoked, about $0.0009 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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