Anchor dependency preparation to checkout root

docs/consumers/delivery.md

@@ -41,7 +41,11 @@ For binary profiles, call `PrepareBuildDependencies` with a
 `DependencyPreparationRequest` selecting the repository and module after
 checkout preparation and before delivery. It runs `go mod download` in that
 module with workspace discovery disabled and the available compatible local Go
-toolchain.
+toolchain. Inside a Git checkout, `RepositoryDir` can name a subdirectory;
+`ModuleDir` is interpreted relative to the containing checkout root, and an
+empty selection chooses that root. Previously, a supplied checkout subdirectory
+acted as the selection base. Outside a checkout, the supplied directory remains
+the base for `ModuleDir`.
 The operation may use the network and updates the Go module cache while
 preserving the caller's proxy, private-module, credential, and cache settings.
 If checksums are missing, Go may update `go.sum`. For binary CI delivery, prepare

docs/roadmap/implementation.md

@@ -110,8 +110,7 @@ and CLI publication tests. Use the offline environment specified in Stage 10.
 
 **Status:** complete. `go test ./internal/git` passes offline, including real
 checkout, worktree, alias, standalone, missing-Git, diagnostic, and failure
-cases. The public Go-only preparation composition check is deferred to Stage 3,
-where preparation adopts discovery.
+cases. The public Go-only preparation composition check passed in Stage 3.
 
 **Files:** `internal/git/source.go` or a focused companion file, Git tests, and
 `internal/process/process.go` only if an existing invocation capability proves
@@ -172,7 +171,9 @@ checkout, discovery fails with the missing-Git cause before Go runs.
 
 ## Stage 3: Apply checkout-root selection to dependency preparation
 
-**Status:** pending. **Depends on:** Stage 2.
+**Status:** complete. Public preparation and CLI `TestCIDeliver` checks pass
+offline, including checkout-relative, symlink, standalone, and missing-Git
+selection. **Depends on:** Stage 2.
 
 **Files:** `preparation.go`, `preparation_test.go`, and
 `docs/consumers/delivery.md`'s preparation guidance.

preparation.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"strings"
 
+	"go.maximumdirect.net/releasekit/internal/git"
 	internalpreparation "go.maximumdirect.net/releasekit/internal/preparation"
 	"go.maximumdirect.net/releasekit/internal/releaseidentity"
 )
@@ -37,11 +38,13 @@ func PrepareTaggedCheckout(ctx context.Context, request TaggedCheckoutRequest) e
 }
 
 // DependencyPreparationRequest selects the repository module whose dependencies
-// should be prepared.
+// should be prepared. Within a checkout, RepositoryDir may name any directory
+// in it; ModuleDir is resolved from the checkout root. Outside a checkout,
+// ModuleDir is resolved from RepositoryDir.
 type DependencyPreparationRequest struct {
 	RepositoryDir string
-	// ModuleDir selects a repository-relative module directory; empty selects
-	// the repository root.
+	// ModuleDir selects a directory relative to the checkout root or standalone
+	// RepositoryDir; empty selects that base.
 	ModuleDir string
 }
 
@@ -55,7 +58,15 @@ func PrepareBuildDependencies(ctx context.Context, request DependencyPreparation
 	if strings.TrimSpace(request.RepositoryDir) == "" {
 		return errors.New("repository directory is required")
 	}
-	selection, err := releaseidentity.ResolveSelection(request.RepositoryDir, request.ModuleDir)
+	base := request.RepositoryDir
+	root, found, err := git.DiscoverRepositoryRoot(ctx, base)
+	if err != nil {
+		return fmt.Errorf("discover dependency preparation repository: %w", err)
+	}
+	if found {
+		base = root
+	}
+	selection, err := releaseidentity.ResolveSelection(base, request.ModuleDir)
 	if err != nil {
 		return fmt.Errorf("resolve dependency preparation module: %w", err)
 	}

preparation_test.go

@@ -249,6 +249,65 @@ func TestPrepareBuildDependenciesUsesSelectedModuleDirectory(t *testing.T) {
 	}
 }
 
+func TestPrepareBuildDependenciesSelectsFromCheckoutRoot(t *testing.T) {
+	repo := t.TempDir()
+	buildGit(t, repo, "init")
+	nested := filepath.Join(repo, "nested")
+	child := filepath.Join(nested, "child")
+	if err := os.MkdirAll(child, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Symlink("nested/child", filepath.Join(repo, "link")); err != nil {
+		t.Fatal(err)
+	}
+	bin := t.TempDir()
+	marker := filepath.Join(t.TempDir(), "directory")
+	if err := os.WriteFile(filepath.Join(bin, "go"), []byte("#!/bin/sh\nprintf '%s' \"$PWD\" > \"$PREPARE_DIR_MARKER\"\n"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("PATH", bin+string(os.PathListSeparator)+os.Getenv("PATH"))
+	t.Setenv("PREPARE_DIR_MARKER", marker)
+	for _, tc := range []struct{ dir, module, want string }{
+		{repo, "", repo}, {child, "", repo}, {repo, "nested", nested},
+		{child, "nested", nested}, {child, "link/..", nested},
+	} {
+		err := releasekit.PrepareBuildDependencies(context.Background(), releasekit.DependencyPreparationRequest{RepositoryDir: tc.dir, ModuleDir: tc.module})
+		got, readErr := os.ReadFile(marker)
+		if err != nil || readErr != nil || string(got) != tc.want {
+			t.Fatalf("selection %q, %q = %q, error %v, read %v; want %q", tc.dir, tc.module, got, err, readErr, tc.want)
+		}
+	}
+}
+
+func TestPrepareBuildDependenciesWithoutGit(t *testing.T) {
+	repo := t.TempDir()
+	buildGit(t, repo, "init")
+	standalone := t.TempDir()
+	bin := t.TempDir()
+	marker := filepath.Join(t.TempDir(), "go-ran")
+	if err := os.WriteFile(filepath.Join(bin, "go"), []byte("#!/bin/sh\nprintf ran > \"$PREPARE_DIR_MARKER\"\n"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("PATH", bin)
+	t.Setenv("PREPARE_DIR_MARKER", marker)
+	if err := releasekit.PrepareBuildDependencies(context.Background(), releasekit.DependencyPreparationRequest{RepositoryDir: standalone}); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(marker); err != nil {
+		t.Fatalf("Go did not run: %v", err)
+	}
+	if err := os.Remove(marker); err != nil {
+		t.Fatal(err)
+	}
+	err := releasekit.PrepareBuildDependencies(context.Background(), releasekit.DependencyPreparationRequest{RepositoryDir: repo})
+	if !errors.Is(err, exec.ErrNotFound) {
+		t.Fatalf("checkout error = %v, want missing Git", err)
+	}
+	if _, err := os.Stat(marker); !os.IsNotExist(err) {
+		t.Fatalf("Go ran after discovery failure: %v", err)
+	}
+}
+
 func publishPreparationTag(t *testing.T, repository string) string {
 	t.Helper()
 	return publishPreparationTagNamed(t, repository, "v1.2.3")