Make workdir consistent with the sidecar structure. (#359)

* Make workdir consistent with the sidecar structure.

Chunk sidecars use /home/user as the home dir, this makes the command
logic reference that known location instead of relative paths.

* Address review: validate workspace path depth, derive sidecar home from env

- ResolveWorkspace now returns (string, error) and errors when repo is
  empty with no saved workspace, preventing rm -rf on the bare home dir
- Replace hardcoded /home/user constant with sidecarHome() which reads
  CHUNK_SIDECAR_HOME env var, falling back to /home/user
- Update callers in sync.go and validate.go
- Add tests for the empty-repo error and env var override

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: webster <michael@webster.fyi>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 3 people

.gitignore

@@ -42,3 +42,4 @@ PLANS.md
 
 # unikraft
 .unikraft/
+test-fetch-on-stale-sidecar.log

internal/cmd/sidecar.go

@@ -454,7 +454,7 @@ func newSidecarSyncCmd() *cobra.Command {
 
 	cmd.Flags().StringVar(&sidecarID, "sidecar-id", "", "Sidecar ID (defaults to active sidecar)")
 	cmd.Flags().StringVar(&identityFile, "identity-file", "", "SSH identity file")
-	cmd.Flags().StringVar(&workdir, "workdir", "", "Destination path on sidecar (auto-detected as ~/workspace/<repo> when omitted)")
+	cmd.Flags().StringVar(&workdir, "workdir", "", "Destination path on sidecar (defaults to /home/user/<repo> when omitted)")
 
 	return cmd
 }

internal/cmd/validate.go

@@ -113,7 +113,7 @@ func newValidateCmd() *cobra.Command {
 	cmd.Flags().StringVar(&opts.sidecarID, "sidecar-id", "", "Sidecar ID for remote execution")
 	cmd.Flags().StringVar(&opts.orgID, "org-id", "", "Organization ID (used when creating a new sidecar)")
 	cmd.Flags().StringVar(&opts.identityFile, "identity-file", "", "SSH identity file (uses ssh-agent or ~/.ssh/chunk_ai when omitted)")
-	cmd.Flags().StringVar(&opts.workdir, "workdir", "", "Working directory on sidecar (reads from sidecar.json, defaults to ./workspace)")
+	cmd.Flags().StringVar(&opts.workdir, "workdir", "", "Working directory on sidecar (reads from sidecar.json, defaults to /home/user/<repo>)")
 	cmd.Flags().BoolVar(&opts.dryRun, "dry-run", false, "Show commands without executing")
 	cmd.Flags().BoolVar(&opts.list, "list", false, "List all configured commands")
 	cmd.Flags().BoolVar(&opts.jsonOut, "json", false, "Output as JSON (only applies with --list)")
@@ -435,7 +435,10 @@ func openSSHSession(ctx context.Context, client *circleci.Client, sidecarID, ide
 	}
 	cwd, _ := os.Getwd()
 	_, repo, _ := gitremote.DetectOrgAndRepo(cwd)
-	dest := sidecar.ResolveWorkspace(ctx, workdir, repo)
+	dest, err := sidecar.ResolveWorkspace(ctx, workdir, repo)
+	if err != nil {
+		return nil, "", &userError{msg: "Could not determine workspace path.", err: err}
+	}
 	merged := hostForwardEnv(rc.CircleCIToken)
 	if merged == nil {
 		merged = make(map[string]string, len(envVars))

internal/sidecar/active_test.go

@@ -223,7 +223,8 @@ func TestResolveWorkspaceCLIFlagWins(t *testing.T) {
 	ctx := context.Background()
 	assert.NilError(t, SaveActive(ctx, ActiveSidecar{SidecarID: "sb-1", Workspace: "/workspace/saved"}))
 
-	got := ResolveWorkspace(ctx, "/workspace/override", "myrepo")
+	got, err := ResolveWorkspace(ctx, "/workspace/override", "myrepo")
+	assert.NilError(t, err)
 	assert.Equal(t, got, "/workspace/override")
 }
 
@@ -235,7 +236,8 @@ func TestResolveWorkspaceSidecarFallback(t *testing.T) {
 	ctx := context.Background()
 	assert.NilError(t, SaveActive(ctx, ActiveSidecar{SidecarID: "sb-1", Workspace: "/workspace/saved"}))
 
-	got := ResolveWorkspace(ctx, "", "myrepo")
+	got, err := ResolveWorkspace(ctx, "", "myrepo")
+	assert.NilError(t, err)
 	assert.Equal(t, got, "/workspace/saved")
 }
 
@@ -244,8 +246,30 @@ func TestResolveWorkspaceDefaultFallback(t *testing.T) {
 	t.Chdir(dir)
 	setupXDGData(t)
 
-	got := ResolveWorkspace(context.Background(), "", "myrepo")
-	assert.Equal(t, got, "./workspace/myrepo")
+	got, err := ResolveWorkspace(context.Background(), "", "myrepo")
+	assert.NilError(t, err)
+	assert.Equal(t, got, "/home/user/myrepo")
+}
+
+func TestResolveWorkspaceEmptyRepoErrors(t *testing.T) {
+	dir := t.TempDir()
+	t.Chdir(dir)
+	setupXDGData(t)
+
+	_, err := ResolveWorkspace(context.Background(), "", "")
+	assert.ErrorContains(t, err, "repo name is empty")
+}
+
+func TestResolveWorkspaceSidecarHomeEnvVar(t *testing.T) {
+	dir := t.TempDir()
+	t.Chdir(dir)
+	setupXDGData(t)
+
+	t.Setenv("CHUNK_SIDECAR_HOME", "/home/runner")
+
+	got, err := ResolveWorkspace(context.Background(), "", "myrepo")
+	assert.NilError(t, err)
+	assert.Equal(t, got, "/home/runner/myrepo")
 }
 
 func TestSidecarFileNameCases(t *testing.T) {

internal/sidecar/sync.go

@@ -14,21 +14,31 @@ import (
 	"github.com/CircleCI-Public/chunk-cli/internal/iostream"
 )
 
-const workspaceDir = "./workspace"
+// sidecarHome returns the base home directory on the sidecar. It reads
+// CHUNK_SIDECAR_HOME so the default "/home/user" can be overridden when the
+// image uses a different OS user.
+func sidecarHome() string {
+	if h := os.Getenv("CHUNK_SIDECAR_HOME"); h != "" {
+		return h
+	}
+	return "/home/user"
+}
 
 // ResolveWorkspace determines the workspace path. Priority:
-// 1. CLI --workdir flag  2. sidecar.json workspace  3. default ./workspace/<repo>.
-func ResolveWorkspace(ctx context.Context, cliWorkdir, repo string) string {
+// 1. CLI --workdir flag  2. sidecar.json workspace  3. default <sidecarHome>/<repo>.
+// Returns an error if no repo-specific path can be determined (repo empty and no
+// saved workspace), because the bare home dir is not safe to pass to rm -rf.
+func ResolveWorkspace(ctx context.Context, cliWorkdir, repo string) (string, error) {
 	if cliWorkdir != "" {
-		return cliWorkdir
+		return cliWorkdir, nil
 	}
 	if active, err := LoadActive(ctx); err == nil && active != nil && active.Workspace != "" {
-		return active.Workspace
+		return active.Workspace, nil
 	}
 	if repo == "" {
-		return workspaceDir
+		return "", fmt.Errorf("sync: cannot determine workspace: repo name is empty and no workspace is saved")
 	}
-	return workspaceDir + "/" + repo
+	return sidecarHome() + "/" + repo, nil
 }
 
 // persistWorkspace saves the resolved workspace back to the sidecar file if it
@@ -48,7 +58,7 @@ func persistWorkspace(ctx context.Context, workspace string) error {
 // Sync synchronises local changes to a sidecar over SSH.
 // It ensures the workspace base exists, clones the repo into workdir if absent,
 // then resets to the remote base and applies a patch of local changes.
-// workdir overrides the destination path; defaults to /workspace/<repo>.
+// workdir overrides the destination path; defaults to /home/user/<repo>.
 func Sync(ctx context.Context,
 	client *circleci.Client, sidecarID, identityFile, authSock, workdir string, status iostream.StatusFunc) error {
 
@@ -67,7 +77,10 @@ func Sync(ctx context.Context,
 		return &NoOriginRemoteError{Err: err}
 	}
 
-	repoPath := ResolveWorkspace(ctx, workdir, repo)
+	repoPath, err := ResolveWorkspace(ctx, workdir, repo)
+	if err != nil {
+		return err
+	}
 
 	if err := persistWorkspace(ctx, repoPath); err != nil {
 		status(iostream.LevelWarn, fmt.Sprintf("Could not save workspace: %v", err))