modfind

Centralized Go module discovery + replace/cache classification for webtyp tooling.

Runs go list -m -json all once per project root, caches it, and classifies each module as writable (main module or local replace → tooling may generate files there) or read-only (module cache → read only). Replaces the byte-identical go list -m -json all loops previously copy-pasted in ssr, image/min, and imagemin.

Sibling to depfind: depfind maps the package import graph ("which main to recompile"); modfind enumerates modules ("where each module lives, and may I write there"). Called only by tool-side code (compiles everywhere, no build tags); deps: stdlib + webtyp/fmt.

Usage

f := modfind.New()
mods, err := f.Discover(rootDir) // []modfind.Module, cached after first call

for _, m := range mods {
    if m.Writable() {
        // main module or local replace → generate files in m.Dir
    } else {
        // read-only cache → only read m.Dir
    }
}

Inject the contract, not the Finder

Consumers take a modfind.Discoverer; the composition root builds the *Finder; tests pass a fake.

type AssetGenerator struct {
    Finder modfind.Discoverer
}

In a tool with several consumers (assets + schema), construct one *modfind.Finder and inject it into each (ssr, image, ormc) so go list runs a single time per session.

Local checkouts

In this ecosystem, the developer checks out many repositories under a single *.code-workspace root. To find where a developer edits a dependency (which may not be m.Dir, since that is often the read-only cache):

// m.SourceDir() returns the local checkout if one exists, else m.Dir
src := m.SourceDir()

You can also search the workspace directly:

root := modfind.WorkspaceRoot(dir)
allMods, err := modfind.WorkspaceModules(root)

Module

Field	Meaning
Path	import path
Dir	on-disk dir (cache path or local replace path)
Version	empty for main / local replace
IsMain	the project's root module
IsReplace	satisfied by a local filesystem replace (writable)
Indirect	transitive dependency
LocalDir	the developer's local checkout of this module (if found under the workspace root)
Writable()	`IsMain

Docs

• docs/ARCHITECTURE.md — what modfind is: the Module model, the writable/read-only classification, the finder API, and constraints.
• docs/DESIGN.md — why a dedicated package (not depfind, devflow, or app) and the duplication it removes.