test+docs: add editor tests; document HEXAI_EDITOR/EDITOR and Custom prompt; seam client in CLI for tests

7 files changed, 143 insertions, 4 deletions

diff --git a/PROJECTSTATUS.md b/PROJECTSTATUS.md
index d1d865a..8709378 100644
--- a/PROJECTSTATUS.md
+++ b/PROJECTSTATUS.md
@@ -4,6 +4,8 @@ This documents shows future items and in progress items. Already completed ones
 
 ## Features
 
+* [/] EDITOR support for custom action in hexai-tmux-action
+* [/] EDITOR support for hexai when no args given
 * [ ] In-editor chat triggers should be context aware of the current file, buffer and function!
 * [ ] Kagi FastGPT for in-editor search
   - Think about an in-editor chat trigger, maybe with S> for search!
diff --git a/docs/configuration.md b/docs/configuration.md
index 11f23c1..e37f743 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -56,6 +56,12 @@ This is mostly useful when Helix runs in a [tmux](https://tmux.github.io/) sessi
   - `--tmux-percent N` split size percentage (default: `33`).
   - `--ui-child` internal; used by the parent process when spawning inside tmux.
 
+Editor integration
+
+- Hexai tries to launch your preferred editor when needed (e.g., TUI “Custom prompt”, CLI with no args).
+- Editor resolution: `HEXAI_EDITOR`, falling back to `EDITOR` when unset.
+- Invocation form: `EDITOR /tmp/hexai-XXXX.md` (a temporary Markdown file).
+
 Code action prompts
 
 - All prompts can be customized under `[prompts.code_action]` in `config.toml`. In addition to `rewrite_*`, `diagnostics_*`, `document_*`, and `go_test_*`, the following templates control the “Simplify and improve” action:
diff --git a/docs/usage.md b/docs/usage.md
index 925ac26..293b038 100644
--- a/docs/usage.md
+++ b/docs/usage.md
@@ -109,6 +109,7 @@ hexai 'install ripgrep on macOS and explain'
 
 - Choose an action with arrow keys, `j/k`, `g/G`, Enter, or hotkeys `[s] [r] [c] [t]`.
   - Includes: Rewrite selection, Simplify and improve, Document code, Generate Go unit test(s), Skip.
+  - “Custom prompt” (hotkey `[p]`) opens your editor (`$HEXAI_EDITOR` or `$EDITOR`) on a temporary `.md` file to write a free-form instruction.
 - Output is written to stdout by default, or to a file via `--outfile`.
 
 Input formats
diff --git a/internal/editor/editor_test.go b/internal/editor/editor_test.go
new file mode 100644
index 0000000..df6dec7
--- /dev/null
+++ b/internal/editor/editor_test.go
@@ -0,0 +1,39 @@
+package editor
+
+import (
+    "os"
+    "path/filepath"
+    "testing"
+)
+
+func TestResolve_EnvPriority(t *testing.T) {
+    t.Setenv("HEXAI_EDITOR", "ed1")
+    t.Setenv("EDITOR", "ed2")
+    ed, err := Resolve()
+    if err != nil || ed != "ed1" {
+        t.Fatalf("Resolve failed: %v %q", err, ed)
+    }
+    t.Setenv("HEXAI_EDITOR", "")
+    ed, err = Resolve()
+    if err != nil || ed != "ed2" {
+        t.Fatalf("Resolve fallback failed: %v %q", err, ed)
+    }
+}
+
+func TestOpenTempAndEdit_UsesRunEditor(t *testing.T) {
+    old := RunEditor
+    t.Cleanup(func(){ RunEditor = old })
+    // Ensure Resolve() succeeds
+    t.Setenv("HEXAI_EDITOR", "dummy")
+    var capturedPath string
+    RunEditor = func(editor, path string) error {
+        capturedPath = path
+        // simulate user writing content
+        return os.WriteFile(path, []byte("Hello\nWorld\n"), 0o600)
+    }
+    out, err := OpenTempAndEdit([]byte("# Start\n\n"))
+    if err != nil { t.Fatalf("OpenTempAndEdit: %v", err) }
+    if out != "Hello\nWorld" { t.Fatalf("unexpected content: %q", out) }
+    if filepath.Ext(capturedPath) != ".md" { t.Fatalf("expected .md suffix: %s", capturedPath) }
+}
+
diff --git a/internal/hexaiaction/custom_action_test.go b/internal/hexaiaction/custom_action_test.go
new file mode 100644
index 0000000..451a313
--- /dev/null
+++ b/internal/hexaiaction/custom_action_test.go
@@ -0,0 +1,39 @@
+package hexaiaction
+
+import (
+    "bytes"
+    "context"
+    "testing"
+
+    "codeberg.org/snonux/hexai/internal/appconfig"
+    "codeberg.org/snonux/hexai/internal/editor"
+    "codeberg.org/snonux/hexai/internal/llm"
+    "os"
+)
+
+type llmFake2 struct{}
+func (llmFake2) Chat(_ context.Context, _ []llm.Message, _ ...llm.RequestOption) (string, error) { return "DONE", nil }
+func (llmFake2) Name() string { return "fake" }
+func (llmFake2) DefaultModel() string { return "m" }
+
+func TestActionCustom_UsesEditorPrompt(t *testing.T) {
+    // Seam: choose custom, fake client, and fake editor
+    oldChoose := chooseActionFn
+    oldNew := newClientFromApp
+    chooseActionFn = func() (ActionKind, error) { return ActionCustom, nil }
+    newClientFromApp = func(_ appconfig.App) (llm.Client, error) { return llmFake2{}, nil }
+    t.Cleanup(func(){ chooseActionFn = oldChoose; newClientFromApp = oldNew })
+
+    oldRunEd := editor.RunEditor
+    editor.RunEditor = func(_ string, path string) error {
+        return os.WriteFile(path, []byte("make it done"), 0o600)
+    }
+    t.Cleanup(func(){ editor.RunEditor = oldRunEd })
+    t.Setenv("HEXAI_EDITOR", "dummy")
+
+    in := bytes.NewBufferString("some code")
+    var out bytes.Buffer
+    var errb bytes.Buffer
+    if err := Run(context.Background(), in, &out, &errb); err != nil { t.Fatalf("Run: %v", err) }
+    if out.String() == "" { t.Fatalf("expected output") }
+}
diff --git a/internal/hexaicli/editor_integration_test.go b/internal/hexaicli/editor_integration_test.go
new file mode 100644
index 0000000..1bebf75
--- /dev/null
+++ b/internal/hexaicli/editor_integration_test.go
@@ -0,0 +1,51 @@
+package hexaicli
+
+import (
+    "bytes"
+    "context"
+    "os"
+    "testing"
+
+    "codeberg.org/snonux/hexai/internal/appconfig"
+    "codeberg.org/snonux/hexai/internal/editor"
+    "codeberg.org/snonux/hexai/internal/llm"
+)
+
+type cliFake struct{}
+func (cliFake) Chat(_ context.Context, _ []llm.Message, _ ...llm.RequestOption) (string, error) { return "OUT", nil }
+func (cliFake) Name() string { return "fake" }
+func (cliFake) DefaultModel() string { return "m" }
+func (cliFake) CodeCompletion(context.Context, string, string, int, string, float64) ([]string, error) { return nil, nil }
+
+func TestRun_NoArgs_OpensEditor(t *testing.T) {
+    // Seam: fake client and editor
+    oldNew := newClientFromApp
+    newClientFromApp = func(_ appconfig.App) (llm.Client, error) { return cliFake{}, nil }
+    t.Cleanup(func(){ newClientFromApp = oldNew })
+    oldRun := editor.RunEditor
+    editor.RunEditor = func(_ string, path string) error { return os.WriteFile(path, []byte("PROMPT"), 0o600) }
+    t.Cleanup(func(){ editor.RunEditor = oldRun })
+    t.Setenv("HEXAI_EDITOR", "dummy")
+
+    // Provide stdin selection
+    var stdout, stderr bytes.Buffer
+    if err := Run(context.Background(), nil, bytes.NewBufferString("SELECTION"), &stdout, &stderr); err != nil {
+        t.Fatalf("Run: %v", err)
+    }
+    if stdout.String() == "" { t.Fatalf("expected some output") }
+}
+
+func TestRun_WithArgs_DoesNotOpenEditor(t *testing.T) {
+    // Provide args; still use fake client
+    oldNew := newClientFromApp
+    newClientFromApp = func(_ appconfig.App) (llm.Client, error) { return cliFake{}, nil }
+    t.Cleanup(func(){ newClientFromApp = oldNew })
+    // Stub editor and detect if called (should not be)
+    called := false
+    oldRun := editor.RunEditor
+    editor.RunEditor = func(_ string, _ string) error { called = true; return nil }
+    t.Cleanup(func(){ editor.RunEditor = oldRun })
+    var stdout, stderr bytes.Buffer
+    if err := Run(context.Background(), []string{"ARG"}, bytes.NewBufferString("SEL"), &stdout, &stderr); err != nil { t.Fatalf("Run: %v", err) }
+    if called { t.Fatalf("editor should not be invoked when args provided") }
+}
diff --git a/internal/hexaicli/run.go b/internal/hexaicli/run.go
index 98e4c40..6017e51 100644
--- a/internal/hexaicli/run.go
+++ b/internal/hexaicli/run.go
@@ -25,7 +25,7 @@ func Run(ctx context.Context, args []string, stdin io.Reader, stdout, stderr io.
     // Load configuration with a logger so file-based config is respected.
     logger := log.New(stderr, "hexai ", log.LstdFlags|log.Lmsgprefix)
     cfg := appconfig.Load(logger)
-    client, err := llmutils.NewClientFromApp(cfg)
+    client, err := newClientFromApp(cfg)
 	if err != nil {
 		fmt.Fprintf(stderr, logging.AnsiBase+"hexai: LLM disabled: %v"+logging.AnsiReset+"\n", err)
 		return err
@@ -154,6 +154,7 @@ func printProviderInfo(errw io.Writer, client llm.Client) {
 }
 
 // newClientFromConfig is kept for tests; delegates to llmutils.
-func newClientFromConfig(cfg appconfig.App) (llm.Client, error) {
-    return llmutils.NewClientFromApp(cfg)
-}
+var newClientFromApp = llmutils.NewClientFromApp
+
+// Backcompat for tests referencing the older helper name.
+func newClientFromConfig(cfg appconfig.App) (llm.Client, error) { return newClientFromApp(cfg) }