build: keep node_modules out of the Go module

.golangci.yml

@@ -22,6 +22,7 @@ linters:
       - vendor
       - dist
       - site
+      - node_modules
     rules:
       # Test files use literal strings for clarity
       - linters: [goconst]

go.mod

@@ -34,3 +34,5 @@ require (
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20260706201446-f0a921348800 // indirect
 	google.golang.org/protobuf v1.36.12 // indirect
 )
+
+ignore node_modules

internal/compliance/go_mod_ignore_test.go

@@ -0,0 +1,58 @@
+//   /    ctx:                         https://ctx.ist
+// ,'`./    do you remember?
+// `.,'\
+//   \    Copyright 2026-present Context contributors.
+//                 SPDX-License-Identifier: Apache-2.0
+
+package compliance
+
+import (
+	"encoding/json"
+	"os/exec"
+	"testing"
+)
+
+// TestGoModIgnoresNodeModules verifies that the root go.mod
+// carries an `ignore node_modules` directive.
+//
+// npm packages may ship Go sources (flatted does, under
+// flatted/golang/). Without the directive, `./...` matches
+// them as packages of this module, so `go build`, `go vet`,
+// `go test`, and golangci-lint all compile and lint
+// third-party code the moment anyone runs `npm install` in
+// editors/vscode, ctx-desktop, or tools/typecheck/*. The
+// bare form (no `./` prefix) matches a node_modules
+// directory at any depth.
+//
+// The directive is read through `go mod edit -json` rather
+// than by string search, so an ignore block or a reformat
+// cannot fool the check.
+//
+// See specs/go-ignore-node-modules.md.
+func TestGoModIgnoresNodeModules(t *testing.T) {
+	root := projectRoot(t)
+
+	cmd := exec.Command("go", "mod", "edit", "-json")
+	cmd.Dir = root
+	out, runErr := cmd.Output()
+	if runErr != nil {
+		t.Fatalf("go mod edit -json: %v", runErr)
+	}
+
+	var mod struct {
+		Ignore []struct {
+			Path string
+		}
+	}
+	if parseErr := json.Unmarshal(out, &mod); parseErr != nil {
+		t.Fatalf("parse go mod edit -json output: %v", parseErr)
+	}
+
+	for _, ig := range mod.Ignore {
+		if ig.Path == "node_modules" {
+			return
+		}
+	}
+	t.Errorf("go.mod is missing `ignore node_modules`; " +
+		"add it with: go mod edit -ignore=node_modules")
+}

specs/go-ignore-node-modules.md

@@ -0,0 +1,65 @@
+# Keep node_modules Out of the Go Module
+
+The repo holds four npm packages (`editors/vscode`, `ctx-desktop`,
+`tools/typecheck/opencode`, `tools/typecheck/pi`) inside the root
+Go module. npm dependencies may ship Go sources, and nothing kept
+Go tooling from treating them as part of ctx.
+
+## Problem
+
+`flatted` (pulled in by eslint through `flat-cache`) ships
+`flatted/golang/pkg/flatted/flatted.go`. After `npm install` in
+`editors/vscode`:
+
+- `go list ./...` reports
+  `github.com/ActiveMemory/ctx/editors/vscode/node_modules/flatted/golang/pkg/flatted`
+  as a package of this module, so `go build`, `go vet`, and
+  `go test ./...` compile it.
+- `make lint` fails with two `govet` findings inside that file.
+- `make test` fails in `TestGolangciLint`, which shells out to
+  golangci-lint.
+
+CI never saw it, because the Go jobs don't run `npm install`. Any
+contributor who works on the extension and then runs `make lint`
+does.
+
+`./...` skips only directories starting with `.` or `_`,
+`testdata`, and nested modules; `node_modules` is none of those.
+golangci-lint's `exclusions.paths` only hides reported issues: the
+package is still loaded and type-checked.
+
+## Solution
+
+1. **`go.mod`: `ignore node_modules`** (Go 1.25+). The bare form,
+   without a `./` prefix, matches a `node_modules` directory at
+   any depth (`./node_modules` would match only the root, which
+   was verified to leave the package in `go list ./...`). This
+   removes the directory from `./...` for every Go command,
+   golangci-lint included, since it loads packages through the
+   go command.
+2. **`.golangci.yml`: `node_modules` in `exclusions.paths`**,
+   beside `vendor`, `dist`, and `site`. With (1) in place this is
+   belt-and-braces; it states in the linter's own config that
+   node code is not in scope, and holds if golangci-lint is ever
+   pointed at an explicit path.
+3. **Regression guard:**
+   `internal/compliance/go_mod_ignore_test.go` reads go.mod via
+   `go mod edit -json` and fails if the directive is missing.
+
+The compliance tests' own file walkers (`allGoFiles`,
+`allSourceFiles`) already skip `node_modules`; they need no
+change.
+
+## Verification
+
+With `editors/vscode/node_modules` installed:
+
+- `go list ./... | grep node_modules` prints nothing.
+- `make lint`: 0 issues. `make test`: passes.
+- `TestGoModIgnoresNodeModules` passes, and fails after
+  `go mod edit -dropignore=node_modules`.
+
+## Non-Goals
+
+- `tools/ctxctl` is a separate module with no npm package inside
+  it; its go.mod is unchanged.