feat: add Custom prompt action (p) with editor integration; shared editor helper in internal/editor; hexai CLI opens editor when no args

1 files changed, 70 insertions, 0 deletions

diff --git a/internal/editor/editor.go b/internal/editor/editor.go
new file mode 100644
index 0000000..44aa1d4
--- /dev/null
+++ b/internal/editor/editor.go
@@ -0,0 +1,70 @@
+package editor
+
+import (
+    "errors"
+    "os"
+    "os/exec"
+    "path/filepath"
+    "strings"
+)
+
+// Resolve returns the editor command from HEXAI_EDITOR or EDITOR.
+func Resolve() (string, error) {
+    ed := strings.TrimSpace(os.Getenv("HEXAI_EDITOR"))
+    if ed == "" {
+        ed = strings.TrimSpace(os.Getenv("EDITOR"))
+    }
+    if ed == "" {
+        return "", errors.New("no editor configured (set HEXAI_EDITOR or EDITOR)")
+    }
+    return ed, nil
+}
+
+// RunEditor is the seam that invokes the editor on the given file path.
+// Override in tests to avoid launching a real editor.
+var RunEditor = func(editor, path string) error {
+    cmd := exec.Command(editor, path)
+    cmd.Stdin = os.Stdin
+    cmd.Stdout = os.Stdout
+    cmd.Stderr = os.Stderr
+    return cmd.Run()
+}
+
+// OpenTempAndEdit creates a temporary .md file, writes initial content if provided,
+// opens it in the resolved editor, then reads the final content and removes the file.
+// Returns the trimmed content.
+func OpenTempAndEdit(initial []byte) (string, error) {
+    ed, err := Resolve()
+    if err != nil {
+        return "", err
+    }
+    // Create temp file under system temp dir; ensure .md suffix
+    dir := os.TempDir()
+    f, err := os.CreateTemp(dir, "hexai-*.md")
+    if err != nil {
+        return "", err
+    }
+    path := f.Name()
+    defer func() { _ = os.Remove(path) }()
+    if len(initial) > 0 {
+        if _, err := f.Write(initial); err != nil {
+            _ = f.Close()
+            return "", err
+        }
+    }
+    if err := f.Sync(); err != nil {
+        _ = f.Close()
+        return "", err
+    }
+    if err := f.Close(); err != nil {
+        return "", err
+    }
+    if err := RunEditor(ed, path); err != nil {
+        return "", err
+    }
+    b, err := os.ReadFile(filepath.Clean(path))
+    if err != nil {
+        return "", err
+    }
+    return strings.TrimSpace(string(b)), nil
+}