Add local WebLLM and NodePod browser runtime

[nick-pape]

Summary

• add a browser WebLLM/Qwen model option with manual workspace tool handling
• add NodePod-backed browser workspace runtime and make it the default demo runtime
• keep WebContainer available as an alternate runtime while sharing browser workspace MCP tooling

Stacking note

This PR is stacked on #31. Review/merge #31 first, then rebase this branch onto main.

Validation

• rush test --to @fledgling/workspace-nodepod
• rush build --to @fledgling/web-demo

[Copilot]

Pull request overview

Adds a browser-focused demo/runtime stack: a shared browser MCP workspace sidecar (@fledgling/mcp-workspace-browser), a NodePod-backed workspace runtime, and a Vite-based web demo that can run either a remote OpenAI model or a local WebLLM Qwen model (with a manual tool-call fallback when function calling isn’t available).

Changes:

• Introduce @fledgling/mcp-workspace-browser as the shared browser workspace runtime + MCP sidecar/tooling layer, and refactor WebContainer runtime to reuse it.
• Add @fledgling/workspace-nodepod implementing the shared workspace runtime interface on top of NodePod.
• Add @fledgling/web-demo (Vite + React) with OpenAI and WebLLM/Qwen model options, plus NodePod/WebContainer runtime switching.

Reviewed changes

Copilot reviewed 44 out of 46 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
rush.json	Adds new workspace packages to the Rush monorepo.
packages/mcp-workspace-browser/package.json	New shared browser workspace sidecar package definition.
packages/mcp-workspace-browser/tsconfig.json	TS config for the new browser workspace package.
packages/mcp-workspace-browser/vitest.config.ts	Vitest config for the new browser workspace package.
packages/mcp-workspace-browser/eslint.config.cjs	ESLint rig wiring for the new browser workspace package.
packages/mcp-workspace-browser/config/rig.json	Heft rig config for the new browser workspace package.
packages/mcp-workspace-browser/src/index.ts	Exports the new browser workspace runtime + sidecar.
packages/mcp-workspace-browser/src/runtime.ts	Defines shared IWorkspaceRuntime + path helpers for browser workspaces.
packages/mcp-workspace-browser/src/runtime.test.ts	Unit tests for the shared browser workspace helpers.
packages/mcp-workspace-browser/src/sidecar.ts	Implements MCP sidecar + tool registration for browser workspaces.
packages/mcp-workspace-webcontainer/package.json	Adds dependency on @fledgling/mcp-workspace-browser.
packages/mcp-workspace-webcontainer/src/runtime.ts	Refactors runtime to reuse shared browser workspace helpers/types.
packages/mcp-workspace-webcontainer/src/index.ts	Re-exports shared browser workspace APIs from the webcontainer package.
packages/workspace-nodepod/package.json	New NodePod-backed browser workspace runtime package definition.
packages/workspace-nodepod/tsconfig.json	TS config for the new NodePod runtime package.
packages/workspace-nodepod/vitest.config.ts	Vitest config for the new NodePod runtime package.
packages/workspace-nodepod/eslint.config.cjs	ESLint rig wiring for the new NodePod runtime package.
packages/workspace-nodepod/config/rig.json	Heft rig config for the new NodePod runtime package.
packages/workspace-nodepod/src/index.ts	Exports the NodePod workspace runtime.
packages/workspace-nodepod/src/runtime.ts	Implements IWorkspaceRuntime on top of NodePod FS + process APIs.
packages/workspace-nodepod/src/runtime.test.ts	Unit tests for path normalization and command execution behavior.
packages/web-agent/package.json	Switches dependency from webcontainer workspace package to browser workspace package.
packages/web-agent/src/index.ts	Re-exports browser workspace APIs (instead of webcontainer workspace APIs).
packages/web-agent/src/dependencies.ts	Uses the new shared browser workspace sidecar factory.
packages/web-agent/src/tool-provider.ts	Retypes sidecar dependency to the new shared browser workspace sidecar.
packages/web-agent/src/web-agent.test.ts	Updates IWorkspaceRuntime import to come from the shared browser workspace package.
packages/web-demo/package.json	New Vite/React demo app with WebLLM + NodePod dependencies.
packages/web-demo/tsconfig.json	TS config for the demo app with bundler module resolution.
packages/web-demo/vite.config.ts	Vite config with NodePod plugin + chunking strategy + node:* shims.
packages/web-demo/index.html	New demo HTML entrypoint.
packages/web-demo/.env.example	Documents demo env vars for OpenAI + WebLLM model selection.
packages/web-demo/src/main.tsx	React entrypoint wiring.
packages/web-demo/src/styles.css	Demo UI styling.
packages/web-demo/src/components.tsx	Demo UI components (chat + file browser + runtime panel).
packages/web-demo/src/App.tsx	Demo state machine: workspace boot, session wiring, streaming transcript updates.
packages/web-demo/src/acp-demo.ts	In-browser ACP wiring + workspace/runtime factory for NodePod/WebContainer.
packages/web-demo/src/model-runner.ts	Model runner abstraction supporting OpenAI + WebLLM (manual tool protocol fallback).
packages/web-demo/src/webllm-worker.ts	WebLLM worker entrypoint.
packages/web-demo/src/node-module-shim.ts	Shim for node:module import in the demo build.
packages/web-demo/src/node-process-shim.ts	Shim for node:process import in the demo build.
packages/agent-core/src/index.ts	Exports the new AiSdkModelTurnRunner.
packages/agent-core/src/ai-sdk-model-turn-runner.ts	Adds reusable Vercel AI SDK model-turn runner wrapper.
packages/agent-core/src/ai-sdk-model-turn-runner.test.ts	Unit tests for the new model-turn runner wrapper.
packages/acp-agent/src/agent.ts	Refactors Node ACP agent model runner to use the new shared AI SDK runner.
common/config/rush/pnpm-lock.yaml	Lockfile updates for new packages/deps.
.gitignore	Ignores additional local env file patterns.

Files not reviewed (1)

• common/config/rush/pnpm-lock.yaml: Language not supported

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.