feat(context): scoped DESIGN.md routing for multi-design-system projects

[modius]

What

Adds zero-config scoped DESIGN.md routing to the context loader, so a project with more than one design system can tell impeccable which one applies to the surface being worked on.

Today there's a single DESIGN.md next to PRODUCT.md. Projects that ship, say, an admin app and a public marketing site (different look, shared product story) have no way to load the right design system per task.

How

Drop a DESIGN.md inside a named subdirectory of the context dir, alongside the shared PRODUCT.md, then pass the URL or file path you're working on to context.mjs:

.agents/context/PRODUCT.md            # shared — one product story
.agents/context/admin/DESIGN.md       # scope "admin"
.agents/context/marketing/DESIGN.md   # scope "marketing"

node scripts/context.mjs "https://admin.example.com/users"   # -> admin/DESIGN.md
node scripts/context.mjs "src/marketing/landing.tsx"          # -> marketing/DESIGN.md
node scripts/context.mjs                                       # -> shared DESIGN.md

The loader infers the scope by matching the target's hostname labels / path segments against the scope directory names (host labels take precedence). No config, no hardcoded names — scopes are discovered from the filesystem.

Changes

• skill/scripts/context.mjs: discoverScopes(), inferScope(), resolveDesignPath(); loadContext(cwd, target) gains a designScope field; CLI reads argv[2].
• skill/SKILL.src.md: setup step 1 documents passing the target.
• tests/context.test.mjs: 7 new tests (inferScope, resolveDesignPath, loadContext scoped + unscoped).

Compatibility

Fully backward compatible: with no target argument, or no scope subdirectories, the loader returns the shared DESIGN.md exactly as before. All existing context tests pass (42/42).

Notes

• I changed source only (skill/). The provider copies under the harness dirs are build outputs — they need bun run build:skills to regenerate (I couldn't run the full build locally without the toolchain). Happy to adjust to whatever you prefer for artifact regeneration.
• Motivation: we maintain a local fork of context.mjs for exactly this (a 3-bundle app), and the 3.1→3.5 loader rewrite wiped it — keen to land a generic version upstream so it's maintained for everyone. Glad to iterate on the design (e.g. an explicit scope→pattern map in PRODUCT.md frontmatter) if you'd prefer a different shape.

---

Note

Low Risk
Additive, filesystem-driven context selection with fallback to the existing shared DESIGN.md; no auth, data, or breaking API changes beyond an optional second argument.

Overview
Adds zero-config scoped DESIGN.md routing so projects with multiple design systems (e.g. admin vs marketing) load the right design doc for the surface being worked on, while PRODUCT.md stays project-wide.

Convention: put scoped files under the context directory as <scope>/DESIGN.md (e.g. .agents/context/admin/DESIGN.md) next to shared PRODUCT.md. Pass an optional URL or file path to context.mjs (CLI argv[2], loadContext(cwd, target)). The loader discovers scope folders, tokenizes the target (hostname labels first, then path segments), and picks the first matching scope name; otherwise it uses the shared root DESIGN.md. loadContext now exposes designScope when a scoped file wins.

Docs & tests: SKILL.src.md setup step 1 documents the optional target argument; new unit tests cover inferScope, resolveDesignPath, and scoped vs legacy single-DESIGN.md behavior.

Compatibility: omitting the target or having no scope subdirs behaves exactly as before.

^{Reviewed by Cursor Bugbot for commit 064ab4e. Bugbot is set up for automated code reviews on this repo. Configure here.}