1 files changed, 56 insertions, 0 deletions
diff --git a/internal/executor/container.go b/internal/executor/container.go
index 2c5b7d3..bfce750 100644
--- a/internal/executor/container.go
+++ b/internal/executor/container.go
@@ -271,6 +271,11 @@ func (r *ContainerRunner) Run(ctx context.Context, t *task.Task, e *storage.Exec
 				return fmt.Errorf("git push failed: %w\n%s", err, string(out))
 			}
 		} else {
+			// No commits pushed — check whether the agent left uncommitted work behind.
+			// If so, fail loudly: the work would be silently lost when the sandbox is deleted.
+			if err := detectUncommittedChanges(workspace); err != nil {
+				return err
+			}
 			r.Logger.Info("no new commits to push", "taskID", t.ID)
 		}
 		success = true
@@ -349,3 +354,54 @@ func (r *ContainerRunner) buildInnerCmd(t *task.Task, e *storage.Execution, isRe
 	return []string{"sh", "-c", claudeCmd.String()}
 }
 
+// scaffoldPrefixes are files/dirs written by the harness into the workspace before the agent
+// runs. They are not part of the repo and must not trigger the uncommitted-changes check.
+var scaffoldPrefixes = []string{
+	".claudomator-env",
+	".claudomator-instructions.txt",
+	".agent-home",
+}
+
+func isScaffold(path string) bool {
+	for _, p := range scaffoldPrefixes {
+		if path == p || strings.HasPrefix(path, p+"/") {
+			return true
+		}
+	}
+	return false
+}
+
+// detectUncommittedChanges returns an error if the workspace contains modified or
+// untracked source files that the agent forgot to commit. Scaffold files written by
+// the harness (.claudomator-env, .claudomator-instructions.txt, .agent-home/) are
+// excluded from the check.
+func detectUncommittedChanges(workspace string) error {
+	// Modified or staged tracked files
+	diffOut, err := exec.Command("git", "-c", "safe.directory=*", "-C", workspace,
+		"diff", "--name-only", "HEAD").CombinedOutput()
+	if err == nil {
+		for _, line := range strings.Split(strings.TrimSpace(string(diffOut)), "\n") {
+			if line != "" && !isScaffold(line) {
+				return fmt.Errorf("agent left uncommitted changes (work would be lost on sandbox deletion):\n%s\nInstructions must include: git add -A && git commit && git push origin master", strings.TrimSpace(string(diffOut)))
+			}
+		}
+	}
+
+	// Untracked new source files (excludes gitignored files)
+	lsOut, err := exec.Command("git", "-c", "safe.directory=*", "-C", workspace,
+		"ls-files", "--others", "--exclude-standard").CombinedOutput()
+	if err == nil {
+		var dirty []string
+		for _, line := range strings.Split(strings.TrimSpace(string(lsOut)), "\n") {
+			if line != "" && !isScaffold(line) {
+				dirty = append(dirty, line)
+			}
+		}
+		if len(dirty) > 0 {
+			return fmt.Errorf("agent left untracked files not committed (work would be lost on sandbox deletion):\n%s\nInstructions must include: git add -A && git commit && git push origin master", strings.Join(dirty, "\n"))
+		}
+	}
+
+	return nil
+}
+