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, 11 insertions, 8 deletions

diff --git a/internal/hexaiaction/prompts.go b/internal/hexaiaction/prompts.go
index 4b2d8be..c5e496b 100644
--- a/internal/hexaiaction/prompts.go
+++ b/internal/hexaiaction/prompts.go
@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"codeberg.org/snonux/hexai/internal/appconfig"
+	"codeberg.org/snonux/hexai/internal/chatrun"
 	"codeberg.org/snonux/hexai/internal/llm"
 	"codeberg.org/snonux/hexai/internal/llmutils"
 	"codeberg.org/snonux/hexai/internal/stats"
@@ -115,25 +116,27 @@ func runCustom(ctx context.Context, cfg actionConfig, client chatDoer, ca appcon
 // runOnce sends a single system+user prompt pair to the LLM, strips code
 // fences from the response, records stats, and updates the tmux status line.
 // Pass a zero-value requestArgs{} when no extra options are needed.
+//
+// The LLM invocation and byte/stats accounting are delegated to the shared
+// chatrun package so this surface stays in lock-step with the CLI and LSP. The
+// tmux status update is kept here because it is specific to the action tool's
+// reporting style.
 func runOnce(ctx context.Context, client chatDoer, sys, user string, req requestArgs) (string, error) {
 	msgs := []llm.Message{{Role: "system", Content: sys}, {Role: "user", Content: user}}
-	txt, err := client.Chat(ctx, msgs, req.options...)
+	// runOnce never streams to a writer, so pass nil out.
+	txt, err := chatrun.Invoke(ctx, client, msgs, req.options, nil)
 	if err != nil {
 		return "", err
 	}
 	out := strings.TrimSpace(StripFences(txt))
-	// Contribute to global stats and update tmux status
-	sent := 0
-	for _, m := range msgs {
-		sent += len(m.Content)
-	}
-	recv := len(out)
 	model := strings.TrimSpace(req.model)
 	if model == "" {
 		model = client.DefaultModel()
 	}
 	provider := providerOf(client)
-	_ = stats.Update(ctx, provider, model, sent, recv)
+	// Account for the exchange against the post-fence-strip response so the
+	// recorded recv bytes match what the user actually receives.
+	chatrun.Account(ctx, provider, model, msgs, out)
 	if snap, err := stats.TakeSnapshot(); err == nil {
 		scopeReqs := snap.ScopeReqs(provider, model)
 		scopeRPM := snap.ScopeRPM(provider, model)