copilotkit--copilotkit/showcase/integrations/strands/PARITY_NOTES.md

AWS Strands — LangGraph-Python Parity Notes

This file documents the status of each showcase demo relative to the canonical LangGraph-Python showcase package (showcase/integrations/langgraph-python).

The overall architectural difference between the two packages:

• LangGraph-Python ships one src/agents/<demo>.py module per demo, each bound to its own LangGraph graph via langgraph.json.
• AWS Strands ships a single shared Strands agent (src/agents/agent.py) registered under many agent names in the AG-UI runtime. All demos in the Strands package reuse the same backend; per-demo differentiation happens almost entirely on the frontend via useFrontendTool, useRenderTool, useHumanInTheLoop, useAgentContext, and A2UI catalogs.

This keeps the Strands code base dramatically smaller without sacrificing user-visible functionality — the demo URLs, pages, and interactive flows are all present.

Skipped demos

These demos depend on LangGraph-specific primitives that AWS Strands does not expose at this time:

• gen-ui-interrupt — Built on useLangGraphInterrupt, which hooks directly into the LangGraph interrupt lifecycle. Strands does not provide an equivalent first-class interrupt primitive. The ergonomic replacement is hitl-in-chat (implemented), which uses useHumanInTheLoop on top of a regular frontend tool — Strands supports that natively. Surfaced as a stub page (src/app/demos/gen-ui-interrupt/) and as not_supported_features.gen-ui-interrupt in the manifest.
• interrupt-headless — Same rationale as gen-ui-interrupt. Requires useLangGraphInterrupt's resolve/respond primitive. Not portable. Surfaced as a stub page (src/app/demos/interrupt-headless/) and as not_supported_features.interrupt-headless in the manifest.

MCP Apps — now ported (wave-2 follow-up)

• mcp-apps — shipped (simplified). Dedicated /api/copilotkit-mcp-apps route configures mcpApps.servers: [{ type: "http", url: ..., serverId: "excalidraw" }]. The Strands shared agent has no bespoke MCP tools — the runtime middleware advertises the MCP server's tools to the agent at request time and emits the activity events that CopilotKit's built-in MCPAppsActivityRenderer paints inline as a sandboxed iframe. Mirrors the langgraph-python sibling pattern.

Wave-2 port status for the previously deferred demos:

• byoc-hashbrown — shipped. Dedicated /api/copilotkit-byoc-hashbrown route, hashbrown renderer + catalog, MetricCard/PieChart/BarChart/DealCard components. The strict hashbrown JSON envelope prompt lives in src/agents/byoc_hashbrown.py and is injected into the shared Strands agent as useAgentContext. Incorporates PR #4271 fix from the start (JSON envelope — NOT XML).
• byoc-json-render — shipped. Dedicated /api/copilotkit-byoc-json-render route, @json-render/react renderer with <JSONUIProvider> wrap (PR #4271 fix). Registry forwards children through the MetricCard wrapper so nested dashboards render. Output prompt lives in src/agents/byoc_json_render.py and is mirrored on the frontend via useAgentContext.
• open-gen-ui — shipped. Dedicated /api/copilotkit-ogui route with openGenerativeUI: { agents: ["open-gen-ui", "open-gen-ui-advanced"] }. Minimal variant uses openGenerativeUI.designSkill to steer the LLM toward intricate, educational visualisations.
• open-gen-ui-advanced — shipped. Same route as open-gen-ui; adds openGenerativeUI.sandboxFunctions (evaluateExpression, notifyHost) so the agent-authored iframe can invoke host functions via Websandbox.connection.remote.<name>(...).
• beautiful-chat — shipped (simplified) in the wave-2 follow-up. Polished landing-style chat shell with brand theming and seeded suggestions, sitting on top of the shared Strands agent. Pattern mirrors the spring-ai sibling (showcase/integrations/spring-ai/src/app/demos/beautiful-chat/). Porting the full canonical surface (ExampleCanvas, GenerativeUIExamples, declarative A2UI catalog, theme provider, dedicated runtime that enables openGenerativeUI + a2ui + mcpApps simultaneously) remains out-of-scope future work — see the LangGraph-Python reference in showcase/integrations/langgraph-python/src/app/demos/beautiful-chat/ for the full surface area.

Per-demo prompt specialization caveat

The Strands showcase uses one shared Strands Agent backend (agent_server.py). Wave-2's BYOC demos specialize the LLM's output shape (hashbrown envelope / json-render spec) by injecting the canonical system prompt via useAgentContext on the frontend, rather than by spinning up dedicated Strands Agent instances per demo. The canonical prompts live in src/agents/byoc_hashbrown.py and src/agents/byoc_json_render.py as the single source of truth; the frontend strings mirror them. This keeps the Strands backend topology simple while letting each demo specialize its output contract.

All other LangGraph-Python demos are ported below.

Ported demos

Existing (pre-blitz):

• agentic-chat, hitl (ergonomic HITL), tool-rendering, gen-ui-tool-based, gen-ui-agent, shared-state-read-write, shared-state-streaming, subagents.

Added in this blitz:

• cli-start — manifest-only start command.
• chat-customization-css — scoped CSS re-theme of <CopilotChat />.
• prebuilt-sidebar — <CopilotSidebar />.
• prebuilt-popup — <CopilotPopup />.
• chat-slots — slot-system chat customization.
• headless-simple — minimal chat built on useAgent.
• headless-complete — full headless chat implementation.
• agentic-chat-reasoning — reasoning chain rendered via a custom slot.
• reasoning-default-render — built-in CopilotChatReasoningMessage render.
• frontend-tools — useFrontendTool background-change demo.
• frontend-tools-async — async useFrontendTool handler.
• hitl-in-chat — useHumanInTheLoop ergonomic HITL.
• hitl-in-app — app-level modal HITL via async useFrontendTool.
• tool-rendering-default-catchall — zero-config wildcard tool render.
• tool-rendering-custom-catchall — branded wildcard renderer via useDefaultRenderTool.
• tool-rendering-reasoning-chain — tool renders + reasoning tokens side-by-side.
• readonly-state-agent-context — useAgentContext read-only context.
• declarative-gen-ui — dynamic A2UI via custom catalog.
• a2ui-fixed-schema — A2UI rendered against a known client-side schema.
• multimodal — image + PDF attachments.
• auth — bearer-token gated runtime.
• voice — voice input via @copilotkit/voice.
• agent-config — typed config object forwarded to agent.
• gen-ui-tool-based — tool-triggered generative UI (haiku generator) via useFrontendTool with a custom render. Manifest entry added; the page was already in place from a prior wave.
• tool-rendering-default-catchall — zero-config wildcard tool render via useDefaultRenderTool(). Manifest entry added; page already shipped.
• tool-rendering-custom-catchall — branded wildcard render. Manifest entry added; page already shipped.
• hitl-in-chat-booking — manifest alias of hitl-in-chat; both feature ids point to the same /demos/hitl-in-chat route, mirroring the langgraph-python manifest topology so the harness's per-feature live status surfaces the booking flow as its own row.

The Strands shared agent (src/agents/agent.py) already exposes the tools all of the above need (weather, flights, query_data, schedule_meeting, manage_sales_todos, set_theme_color, generate_a2ui). New demos that need additional agent-side surface are documented inline in their respective demo folders.