improve agent friendliness of view --json

cmd/view.go

@@ -41,6 +41,13 @@ func ViewCmd(cfg *config.Config) *cobra.Command {
 }
 
 func runView(cfg *config.Config, opts *viewOptions) error {
+	// JSON mode must never show interactive prompts so that agents and
+	// scripts always receive machine-readable output.  Resolve the stack
+	// directly (like push/submit) and return typed exit codes.
+	if opts.asJSON {
+		return runViewJSON(cfg)
+	}
+
 	result, err := loadStack(cfg, "")
 	if err != nil {
 		return ErrNotInStack
@@ -52,7 +59,7 @@ func runView(cfg *config.Config, opts *viewOptions) error {
 
 	// Show loading indicator for interactive TUI mode.
 	showingLoader := false
-	if !opts.asJSON && !opts.short && cfg.IsInteractive() {
+	if !opts.short && cfg.IsInteractive() {
 		fmt.Fprintf(cfg.Err, "Loading stack...")
 		showingLoader = true
 	}
@@ -65,17 +72,52 @@ func runView(cfg *config.Config, opts *viewOptions) error {
 		fmt.Fprintf(cfg.Err, "\r\033[2K")
 	}
 
-	if opts.asJSON {
-		return viewJSON(cfg, s, currentBranch)
-	}
-
 	if opts.short {
 		return viewShort(cfg, s, currentBranch)
 	}
 
 	return viewFull(cfg, s, currentBranch, prDetails)
 }
 
+// runViewJSON handles `gh stack view --json` without interactive prompts.
+// It resolves the stack directly and returns typed exit codes when the
+// branch is not part of any stack or belongs to multiple stacks.
+func runViewJSON(cfg *config.Config) error {
+	gitDir, err := git.GitDir()
+	if err != nil {
+		cfg.Errorf("not a git repository")
+		return ErrNotInStack
+	}
+
+	sf, err := stack.Load(gitDir)
+	if err != nil {
+		cfg.Errorf("failed to load stack state: %s", err)
+		return ErrNotInStack
+	}
+
+	currentBranch, err := git.CurrentBranch()
+	if err != nil {
+		cfg.Errorf("failed to get current branch: %s", err)
+		return ErrNotInStack
+	}
+
+	stacks := sf.FindAllStacksForBranch(currentBranch)
+	if len(stacks) == 0 {
+		cfg.Errorf("current branch %q is not part of a stack", currentBranch)
+		return ErrNotInStack
+	}
+	if len(stacks) > 1 {
+		cfg.Errorf("branch %q belongs to multiple stacks; checkout a non-trunk branch first", currentBranch)
+		return ErrDisambiguate
+	}
+	s := stacks[0]
+
+	syncStackPRs(cfg, s)
+	stack.SaveNonBlocking(gitDir, sf)
+
+	return viewJSON(cfg, s, currentBranch)
+}
+
 func viewShort(cfg *config.Config, s *stack.Stack, currentBranch string) error {
 	var repoHost, repoOwner, repoName string
 	if repo, err := cfg.Repo(); err == nil {

cmd/view_test.go

@@ -3,6 +3,8 @@ package cmd
 import (
 	"encoding/json"
 	"io"
+	"os"
+	"path/filepath"
 	"testing"
 	"time"
 
@@ -418,3 +420,119 @@ func indexOf(s, substr string) int {
 	}
 	return -1
 }
+
+// writeStackFileMulti writes a stack file with multiple stacks.
+func writeStackFileMulti(t *testing.T, dir string, stacks ...stack.Stack) {
+	t.Helper()
+	sf := &stack.StackFile{
+		SchemaVersion: 1,
+		Stacks:        stacks,
+	}
+	data, err := json.MarshalIndent(sf, "", "  ")
+	require.NoError(t, err)
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "gh-stack"), data, 0644))
+}
+
+func TestRunViewJSON_NotInStack(t *testing.T) {
+	tmpDir := t.TempDir()
+	writeStackFile(t, tmpDir, stack.Stack{
+		Trunk:    stack.BranchRef{Branch: "main"},
+		Branches: []stack.BranchRef{{Branch: "feat/01"}},
+	})
+
+	restore := git.SetOps(&git.MockOps{
+		GitDirFn:        func() (string, error) { return tmpDir, nil },
+		CurrentBranchFn: func() (string, error) { return "unrelated-branch", nil },
+	})
+	defer restore()
+
+	cfg, _, errR := config.NewTestConfig()
+	cmd := ViewCmd(cfg)
+	cmd.SetArgs([]string{"--json"})
+	cmd.SetOut(io.Discard)
+	cmd.SetErr(io.Discard)
+	err := cmd.Execute()
+
+	cfg.Err.Close()
+	errOut, _ := io.ReadAll(errR)
+
+	assert.ErrorIs(t, err, ErrNotInStack, "expected exit code 2")
+	assert.Contains(t, string(errOut), "not part of a stack")
+}
+
+func TestRunViewJSON_MultipleStacks(t *testing.T) {
+	tmpDir := t.TempDir()
+	// "main" is the trunk of both stacks → disambiguation.
+	writeStackFileMulti(t, tmpDir,
+		stack.Stack{
+			Trunk:    stack.BranchRef{Branch: "main"},
+			Branches: []stack.BranchRef{{Branch: "feat/01"}},
+		},
+		stack.Stack{
+			Trunk:    stack.BranchRef{Branch: "main"},
+			Branches: []stack.BranchRef{{Branch: "feat/02"}},
+		},
+	)
+
+	restore := git.SetOps(&git.MockOps{
+		GitDirFn:        func() (string, error) { return tmpDir, nil },
+		CurrentBranchFn: func() (string, error) { return "main", nil },
+	})
+	defer restore()
+
+	cfg, _, errR := config.NewTestConfig()
+	cmd := ViewCmd(cfg)
+	cmd.SetArgs([]string{"--json"})
+	cmd.SetOut(io.Discard)
+	cmd.SetErr(io.Discard)
+	err := cmd.Execute()
+
+	cfg.Err.Close()
+	errOut, _ := io.ReadAll(errR)
+
+	assert.ErrorIs(t, err, ErrDisambiguate, "expected exit code 6")
+	assert.Contains(t, string(errOut), "belongs to multiple stacks")
+}
+
+func TestRunViewJSON_SingleStack(t *testing.T) {
+	tmpDir := t.TempDir()
+	writeStackFile(t, tmpDir, stack.Stack{
+		Prefix: "feat",
+		Trunk:  stack.BranchRef{Branch: "main", Head: "aaa"},
+		Branches: []stack.BranchRef{
+			{
+				Branch:      "feat/01",
+				Head:        "bbb",
+				Base:        "aaa",
+				PullRequest: &stack.PullRequestRef{Number: 10, URL: "https://github.com/o/r/pull/10"},
+			},
+		},
+	})
+
+	restore := git.SetOps(&git.MockOps{
+		GitDirFn:        func() (string, error) { return tmpDir, nil },
+		CurrentBranchFn: func() (string, error) { return "feat/01", nil },
+		IsAncestorFn:    func(string, string) (bool, error) { return true, nil },
+	})
+	defer restore()
+
+	cfg, outR, _ := config.NewTestConfig()
+	cmd := ViewCmd(cfg)
+	cmd.SetArgs([]string{"--json"})
+	cmd.SetOut(io.Discard)
+	cmd.SetErr(io.Discard)
+	err := cmd.Execute()
+
+	cfg.Out.Close()
+	raw, _ := io.ReadAll(outR)
+
+	require.NoError(t, err)
+
+	var got viewJSONOutput
+	require.NoError(t, json.Unmarshal(raw, &got), "output should be valid JSON: %s", string(raw))
+	assert.Equal(t, "main", got.Trunk)
+	assert.Equal(t, "feat", got.Prefix)
+	assert.Len(t, got.Branches, 1)
+	assert.Equal(t, "feat/01", got.Branches[0].Name)
+	assert.True(t, got.Branches[0].IsCurrent)
+}