plan 10: a step that ran but could not be logged is named in the error

1 files changed, 23 insertions, 1 deletions

diff --git a/internal/engine/apply.go b/internal/engine/apply.go
index 09f3aab..cc87f30 100644
--- a/internal/engine/apply.go
+++ b/internal/engine/apply.go
@@ -113,7 +113,10 @@ func (e *Engine) applyFile(dirName string, c plan.Chain, approved bool, j *journ
 	// Each step is logged the moment it has run (review M9), not after the
 	// whole chain: a run killed mid-chain must leave what it did undoable.
 	results, err := apply.ChainLogged(c, func(i int, sr apply.StepResult) error {
-		return e.logStep(j, run, dirName, rel, i+1, c.Steps[i], sr)
+		if err := e.logStep(j, run, dirName, rel, i+1, c.Steps[i], sr); err != nil {
+			return unloggedStep(rel, c.Steps[i], sr, err)
+		}
+		return nil
 	})
 	if err != nil {
 		return FileResult{}, err
@@ -121,6 +124,25 @@ func (e *Engine) applyFile(dirName string, c plan.Chain, approved bool, j *journ
 	return FileResult{File: c.File, Steps: results}, nil
 }
 
+// unloggedStep is the error for a step whose log entry could not be written
+// (re-review N1). A step that ran is named with where its file is now:
+// undo cannot see it, so the user must be told where to look.
+func unloggedStep(rel string, step plan.Step, sr apply.StepResult, err error) error {
+	if sr.Status != "ok" {
+		return fmt.Errorf("%s: step %s (%s) could not be logged: %w", rel, actionName(step.Kind), sr.Status, err)
+	}
+	var where string
+	switch {
+	case step.Kind == plan.Copy:
+		where = "a copy is at " + xdg.Abbrev(sr.Dst)
+	case sr.Dst != "":
+		where = "the file is now at " + xdg.Abbrev(sr.Dst)
+	default:
+		where = "the file is deleted for good"
+	}
+	return fmt.Errorf("%s: %s ran but could not be logged, so undo cannot see it (%s): %w", rel, actionName(step.Kind), where, err)
+}
+
 // tallyFile updates result's Applied/Failed/Declined counters from one
 // file's step outcomes. The three are not mutually exclusive: a chain that
 // ran one step ok and then failed on the next counts toward both Applied