ADR: Monorepo Conversion (#5199)

* ADR: Monorepo Conversion

* ADR: Add note about releases like `comfyui-frontend-types`

docs/adr/0002-monorepo-conversion.md

@@ -0,0 +1,50 @@
+# 2. Restructure ComfyUI_frontend as a monorepo
+
+Date: 2025-08-25
+
+## Status
+
+Proposed
+
+<!-- [Proposed | Accepted | Rejected | Deprecated | Superseded by [ADR-NNNN](NNNN-title.md)] -->
+
+## Context
+
+[Most of the context is in here](https://github.com/Comfy-Org/ComfyUI_frontend/issues/4661)
+
+TL;DR: As we're merging more subprojects like litegraph, devtools, and soon a fork of PrimeVue,
+ a monorepo structure will help a lot with code sharing and organization.
+
+For more information on Monorepos, check out [monorepo.tools](https://monorepo.tools/)
+
+## Decision
+
+- Swap out NPM for PNPM
+- Add a workspace for the PrimeVue fork
+- Move the frontend code into its own app workspace
+- Longer term: Extract and reorganize common infrastructure to take advantage of the new monorepo tooling
+
+### Tools proposed
+
+[PNPM](https://pnpm.io/) and [PNPM workspaces](https://pnpm.io/workspaces)
+
+For monorepo management, I'd probably go with [Nx](https://nx.dev/), but I could be conviced otherwise.
+There's a [whole list here](https://monorepo.tools/#tools-review) if you're interested.
+
+## Consequences
+
+### Positive
+
+- Adding new projects with shared dependencies becomes really easy
+- Makes the process of forking and customizing projects more structured, if not strictly easier
+- It *could* speed up the build and development process (not guaranteed)
+- It would let us cleanly organize and release packages like `comfyui-frontend-types`
+
+### Negative
+
+- Monorepos take some getting used to
+- Reviews and code contribution management has to account for the different projects' situations and constraints
+
+<!-- ## Notes
+
+Optional section for additional information, references, or clarifications. -->

docs/adr/README.md

@@ -11,6 +11,7 @@ An Architecture Decision Record captures an important architectural decision mad
 | ADR | Title | Status | Date |
 |-----|-------|--------|------|
 | [0001](0001-merge-litegraph-into-frontend.md) | Merge LiteGraph.js into ComfyUI Frontend | Accepted | 2025-08-05 |
+| [0002](0002-monorepo-conversion.md) | Restructure as a Monorepo | Proposed | 2025-08-25 |
 
 ## Creating a New ADR