feat: add MCP Apps (SEP-1865) support to platform and functions SDK

[simplesagar]

Summary

Adds MCP Apps (SEP-1865) support to the Gram platform and Functions SDK, enabling function authors to declare interactive UI resources that MCP-compatible hosts can render in sandboxed iframes.

Key insight: Gram's existing resource pipeline is URI-scheme and MIME-type agnostic — ui:// resources with text/html+mcp flow through the entire stack (manifest → DB → MCP endpoints → runner) with zero infrastructure changes.

Changes

• resource() + uiResource() on the Gram class for declaring resources directly in the SDK
• uiResource() convenience features:
  • Auto-generates ui://{name} URI when uri is omitted
  • body + styles mode wraps content in an HTML scaffold with Gram.onData() communication helper
  • Raw content mode still available for full control
• meta on tools — optional meta?: Record<string, unknown> on ToolDefinition for linking tools to UI resources via "ui/resourceUri"
• fromGram() resource capability — conditionally registers resources/list + resources/read MCP handlers when resources exist
• _meta passthrough fix — fromGram() now correctly passes tool meta as _meta in tools/list responses
• handleResourceRead() — serves resource content (static or lazy/dynamic)
• extend() merges resources from other Gram instances

What it looks like

gram.uiResource({
  name: "bar-chart",
  description: "Interactive bar chart",
  styles: `.chart { display: flex; gap: 4px; }`,
  body: `
    <div id="chart"></div>
    <script>
      Gram.onData((data) => { renderChart(data.values); });
    </script>
  `,
});

gram.tool({
  name: "generate-chart",
  meta: { "ui/resourceUri": "ui://bar-chart" },
  inputSchema: { data: z.array(z.number()) },
  async execute(ctx, input) {
    return ctx.json({ values: input.data });
  },
});

Test plan

• pnpm test — 59 tests pass (31 source + 28 dist)
• New tests for uiResource() auto-URI, scaffold with Gram.onData(), body-only mode
• Existing tests for resource(), handleResourceRead(), meta flow, extend() merges
• Manual MCP Inspector smoke test via fromGram() + stdio transport
• mise build:server — confirm Go type change compiles

RFC: https://www.notion.so/31b726c497cc8106878cfa296200188f

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated (UTC)
gram-docs-redirect	Ready	Preview, Comment	Mar 8, 2026 1:16am

[devin-ai-integration]

✅ Devin Review: No Issues Found

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