From 63aefeb890a485c32f538d2c10aa671a7ae02485 Mon Sep 17 00:00:00 2001
From: Paul Annesley <paul@annesley.cc>
Date: Tue, 7 Apr 2026 16:16:44 +0930
Subject: [PATCH] preflight: if the repo has no remote, skip push & cleanup

This is useful for a pipeline that defines e.g. /path/to/codebase/.git
as the repository, with a buildkite-agent running on that local machine.
Changes to that git repo don't need to be pushed anywhere.

Amp-Thread-ID: https://ampcode.com/threads/T-019d66ad-7398-770a-990d-705838d5dba4
Co-authored-by: Amp <amp@ampcode.com>
---
 cmd/preflight/preflight.go          |  5 ++++-
 internal/preflight/snapshot.go      | 31 ++++++++++++++++++-----------
 internal/preflight/snapshot_test.go | 27 +++++++++++++++++++++++++
 3 files changed, 50 insertions(+), 13 deletions(-)

diff --git a/cmd/preflight/preflight.go b/cmd/preflight/preflight.go
index 3d32a53a..9584434b 100644
--- a/cmd/preflight/preflight.go
+++ b/cmd/preflight/preflight.go
@@ -111,6 +111,9 @@ func (c *PreflightCmd) Run(kongCtx *kong.Context, globals cli.GlobalFlags) error
 			snapshotDetail += fmt.Sprintf("\n %s %s", file.StatusSymbol(), file.Path)
 		}
 	}
+	if result.PushSkipped {
+		snapshotDetail += "\nWarning: no remote \"origin\" found; push skipped"
+	}
 	_ = renderer.Render(Event{Type: EventOperation, Time: time.Now(), PreflightID: preflightID.String(), Title: "Pushed snapshot of working tree...", Detail: snapshotDetail})
 
 	_ = renderer.Render(Event{Type: EventOperation, Time: time.Now(), PreflightID: preflightID.String(), Title: fmt.Sprintf("Creating build on %s/%s...", resolvedPipeline.Org, resolvedPipeline.Name)})
@@ -168,7 +171,7 @@ func (c *PreflightCmd) Run(kongCtx *kong.Context, globals cli.GlobalFlags) error
 	buildResult := NewResult(finalBuild)
 	finalErr := buildResult.Error()
 
-	if !c.NoCleanup {
+	if !c.NoCleanup && !result.PushSkipped {
 		_ = renderer.Render(Event{Type: EventOperation, Time: time.Now(), PreflightID: preflightID.String(), Title: fmt.Sprintf("Cleaning up remote branch %s...", result.Branch)})
 		if cleanupErr := preflight.Cleanup(repoRoot, result.Ref, globals.EnableDebug()); cleanupErr != nil {
 			_ = renderer.Render(Event{Type: EventOperation, Time: time.Now(), PreflightID: preflightID.String(), Title: fmt.Sprintf("Warning: failed to delete remote branch %s: %v", result.Ref, cleanupErr)})
diff --git a/internal/preflight/snapshot.go b/internal/preflight/snapshot.go
index 2784d2f6..ef79a2a6 100644
--- a/internal/preflight/snapshot.go
+++ b/internal/preflight/snapshot.go
@@ -16,10 +16,11 @@ type FileChange struct {
 
 // SnapshotResult holds the output of a successful snapshot operation.
 type SnapshotResult struct {
-	Commit string
-	Ref    string
-	Branch string
-	Files  []FileChange
+	Commit      string
+	Ref         string
+	Branch      string
+	Files       []FileChange
+	PushSkipped bool
 }
 
 func (r SnapshotResult) ShortCommit() string {
@@ -110,17 +111,23 @@ func Snapshot(dir string, preflightID uuid.UUID, opts ...SnapshotOption) (*Snaps
 		return nil, err
 	}
 
-	// Push the commit to the remote branch.
-	refspec := fmt.Sprintf("%s:%s", commit, ref)
-	if err := gitRun(dir, env, cfg.debug, "push", "origin", refspec); err != nil {
-		return nil, err
+	var pushSkipped bool
+	if _, err := gitOutput(dir, env, cfg.debug, "remote", "get-url", "origin"); err != nil {
+		pushSkipped = true
+	} else {
+		// Push the commit to the remote branch.
+		refspec := fmt.Sprintf("%s:%s", commit, ref)
+		if err := gitRun(dir, env, cfg.debug, "push", "origin", refspec); err != nil {
+			return nil, err
+		}
 	}
 
 	return &SnapshotResult{
-		Commit: commit,
-		Ref:    ref,
-		Branch: branch,
-		Files:  files,
+		Commit:      commit,
+		Ref:         ref,
+		Branch:      branch,
+		Files:       files,
+		PushSkipped: pushSkipped,
 	}, nil
 }
 
diff --git a/internal/preflight/snapshot_test.go b/internal/preflight/snapshot_test.go
index 495ba719..6925e403 100644
--- a/internal/preflight/snapshot_test.go
+++ b/internal/preflight/snapshot_test.go
@@ -364,6 +364,33 @@ func TestDiffFiles(t *testing.T) {
 	}
 }
 
+func TestSnapshot_NoRemote(t *testing.T) {
+	worktree := initTestRepo(t)
+
+	// Remove the origin remote.
+	runGit(t, worktree, "remote", "remove", "origin")
+
+	// Add a change so we exercise the commit path too.
+	if err := os.WriteFile(filepath.Join(worktree, "README.md"), []byte("# changed\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	preflightID := uuid.MustParse("00000000-0000-0000-0000-000000000010")
+	result, err := Snapshot(worktree, preflightID)
+	if err != nil {
+		t.Fatalf("Snapshot() error: %v", err)
+	}
+
+	if !result.PushSkipped {
+		t.Error("expected PushSkipped to be true when no remote exists")
+	}
+
+	// The commit should still be valid.
+	if len(result.Commit) != 40 {
+		t.Errorf("expected 40-char SHA, got %q", result.Commit)
+	}
+}
+
 func TestSnapshot_CleanWorktree(t *testing.T) {
 	worktree := initTestRepo(t)