Extract shared chatrun package to eliminate chat-runner DRY violations

The CLI, LSP server and tmux code-action tool each carried near-identical
chat-running logic: invoking the LLM (streaming-aware), collecting the
response, and accounting sent/received bytes into the stats package.

Introduce internal/chatrun with:
- Invoke: streaming-aware LLM call that collects the full response and
  optionally mirrors chunks to a writer (nil writer = collect only).
- SentBytes / Account: shared byte counting and stats.Update.

Wire all three surfaces to it:
- hexaicli: runChatRequest delegates to chatrun.Invoke; summarizeChatRun
  uses chatrun.Account. Removed the duplicated streaming/simple helpers.
- hexaiaction: runOnce uses chatrun.Invoke + chatrun.Account, keeping the
  tmux status update local.
- lsp: chatWithStats and the completion path use chatrun.SentBytes/Invoke;
  extracted unavailableClientError to keep chatWithStats small.

chatrun has 100% test coverage; full suite passes with -race.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

1 files changed, 135 insertions, 0 deletions

diff --git a/internal/chatrun/chatrun_test.go b/internal/chatrun/chatrun_test.go
new file mode 100644
index 0000000..f2f5806
--- /dev/null
+++ b/internal/chatrun/chatrun_test.go
@@ -0,0 +1,135 @@
+package chatrun
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"codeberg.org/snonux/hexai/internal/llm"
+)
+
+// simpleClient implements only Chatter (no streaming).
+type simpleClient struct {
+	resp string
+	err  error
+}
+
+func (c simpleClient) Chat(_ context.Context, _ []llm.Message, _ ...llm.RequestOption) (string, error) {
+	return c.resp, c.err
+}
+
+// streamClient implements Chatter and llm.Streamer.
+type streamClient struct {
+	chunks []string
+	err    error
+}
+
+func (c streamClient) Chat(_ context.Context, _ []llm.Message, _ ...llm.RequestOption) (string, error) {
+	return strings.Join(c.chunks, ""), nil
+}
+
+func (c streamClient) ChatStream(_ context.Context, _ []llm.Message, onDelta func(string), _ ...llm.RequestOption) error {
+	if c.err != nil {
+		return c.err
+	}
+	for _, chunk := range c.chunks {
+		onDelta(chunk)
+	}
+	return nil
+}
+
+// errWriter always fails, to exercise the write-error paths.
+type errWriter struct{ err error }
+
+func (w errWriter) Write([]byte) (int, error) { return 0, w.err }
+
+func TestInvoke_SimpleCollectsAndWrites(t *testing.T) {
+	var out bytes.Buffer
+	got, err := Invoke(context.Background(), simpleClient{resp: "hello"}, nil, nil, &out)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if got != "hello" || out.String() != "hello" {
+		t.Fatalf("got=%q out=%q, want hello/hello", got, out.String())
+	}
+}
+
+func TestInvoke_SimpleNilWriter(t *testing.T) {
+	got, err := Invoke(context.Background(), simpleClient{resp: "x"}, nil, nil, nil)
+	if err != nil || got != "x" {
+		t.Fatalf("got=%q err=%v, want x/nil", got, err)
+	}
+}
+
+func TestInvoke_SimpleChatError(t *testing.T) {
+	_, err := Invoke(context.Background(), simpleClient{err: errors.New("boom")}, nil, nil, nil)
+	if err == nil || !strings.Contains(err.Error(), "boom") {
+		t.Fatalf("expected chat error, got %v", err)
+	}
+}
+
+func TestInvoke_SimpleWriteError(t *testing.T) {
+	_, err := Invoke(context.Background(), simpleClient{resp: "x"}, nil, nil, errWriter{err: errors.New("wfail")})
+	if err == nil || !strings.Contains(err.Error(), "wfail") {
+		t.Fatalf("expected write error, got %v", err)
+	}
+}
+
+func TestInvoke_StreamingCollectsAndWrites(t *testing.T) {
+	var out bytes.Buffer
+	got, err := Invoke(context.Background(), streamClient{chunks: []string{"a", "b", "c"}}, nil, nil, &out)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if got != "abc" || out.String() != "abc" {
+		t.Fatalf("got=%q out=%q, want abc/abc", got, out.String())
+	}
+}
+
+func TestInvoke_StreamingNilWriter(t *testing.T) {
+	got, err := Invoke(context.Background(), streamClient{chunks: []string{"a", "b"}}, nil, nil, nil)
+	if err != nil || got != "ab" {
+		t.Fatalf("got=%q err=%v, want ab/nil", got, err)
+	}
+}
+
+func TestInvoke_StreamingError(t *testing.T) {
+	_, err := Invoke(context.Background(), streamClient{err: errors.New("sfail")}, nil, nil, nil)
+	if err == nil || !strings.Contains(err.Error(), "sfail") {
+		t.Fatalf("expected stream error, got %v", err)
+	}
+}
+
+func TestInvoke_StreamingWriteError(t *testing.T) {
+	// Full text must still be collected even though the writer fails.
+	_, err := Invoke(context.Background(), streamClient{chunks: []string{"a", "b"}}, nil, nil, errWriter{err: errors.New("wfail")})
+	if err == nil || !strings.Contains(err.Error(), "wfail") {
+		t.Fatalf("expected write error, got %v", err)
+	}
+}
+
+func TestSentBytes(t *testing.T) {
+	msgs := []llm.Message{
+		{Role: "system", Content: "abc"},
+		{Role: "user", Content: "de"},
+	}
+	if got := SentBytes(msgs); got != 5 {
+		t.Fatalf("SentBytes = %d, want 5", got)
+	}
+	if got := SentBytes(nil); got != 0 {
+		t.Fatalf("SentBytes(nil) = %d, want 0", got)
+	}
+}
+
+func TestAccount(t *testing.T) {
+	msgs := []llm.Message{{Role: "user", Content: "1234"}}
+	sent, recv := Account(context.Background(), "prov", "model", msgs, "response")
+	if sent != 4 {
+		t.Fatalf("sent = %d, want 4", sent)
+	}
+	if recv != len("response") {
+		t.Fatalf("recv = %d, want %d", recv, len("response"))
+	}
+}