logging: add -log-preview-limit flag with HEXAI_LOG_PREVIEW_LIMIT env; wire through llm.SetLogPreviewLimit; document in README

3 files changed, 30 insertions, 15 deletions

diff --git a/README.md b/README.md
index a671729..ea6a670 100644
--- a/README.md
+++ b/README.md
@@ -46,3 +46,4 @@ Notes:
 | `-context-mode`         | `file-on-new-func` | `HEXAI_CONTEXT_MODE`       | `minimal` `window` `file-on-new-func` `always-full` |
 | `-context-window-lines` | `120`              | `HEXAI_CONTEXT_WINDOW_LINES` | Lines around cursor when using `window` mode.      |
 | `-max-context-tokens`   | `2000`             | `HEXAI_MAX_CONTEXT_TOKENS` | Token budget for additional context.               |
+| `-log-preview-limit`    | `0` (unlimited)    | `HEXAI_LOG_PREVIEW_LIMIT`  | Limit characters shown in LLM preview logs.        |
diff --git a/internal/llm/openai.go b/internal/llm/openai.go
index 45cb1b8..7cfabc1 100644
--- a/internal/llm/openai.go
+++ b/internal/llm/openai.go
@@ -95,8 +95,8 @@ func (c *openAIClient) Chat(ctx context.Context, messages []Message, opts ...Req
 	start := time.Now()
 	c.logf("chat start model=%s temp=%.2f max_tokens=%d stop=%d messages=%d", o.Model, o.Temperature, o.MaxTokens, len(o.Stop), len(messages))
     for i, m := range messages {
-        // Sending context (cyan) — log full content with real newlines
-        c.logf("msg[%d] role=%s size=%d preview=%s%s%s", i, m.Role, len(m.Content), ansiCyan, m.Content, ansiNormal)
+        // Sending context (cyan)
+        c.logf("msg[%d] role=%s size=%d preview=%s%s%s", i, m.Role, len(m.Content), ansiCyan, previewForLog(m.Content), ansiNormal)
     }
 	req := oaChatRequest{Model: o.Model}
 	req.Messages = make([]oaMessage, len(messages))
@@ -154,8 +154,8 @@ func (c *openAIClient) Chat(ctx context.Context, messages []Message, opts ...Req
         return "", errors.New("openai: no choices returned")
     }
     content := out.Choices[0].Message.Content
-    // Received context (green) — log full content with real newlines
-    c.logf("success choice=0 finish=%s size=%d preview=%s%s%s duration=%s", out.Choices[0].FinishReason, len(content), ansiGreen, content, ansiNormal, time.Since(start))
+    // Received context (green)
+    c.logf("success choice=0 finish=%s size=%d preview=%s%s%s duration=%s", out.Choices[0].FinishReason, len(content), ansiGreen, previewForLog(content), ansiNormal, time.Since(start))
     return content, nil
 }
 
diff --git a/internal/llm/provider.go b/internal/llm/provider.go
index fd9d4d3..a80b1c1 100644
--- a/internal/llm/provider.go
+++ b/internal/llm/provider.go
@@ -1,10 +1,10 @@
 package llm
 
 import (
-	"context"
-	"errors"
-	"log"
-	"os"
+    "context"
+    "errors"
+    "log"
+    "os"
 )
 
 // Message represents a chat-style prompt message.
@@ -16,8 +16,8 @@ type Message struct {
 // Client is a minimal LLM provider interface.
 // Future providers (Ollama, etc.) should implement this.
 type Client interface {
-	// Chat sends chat messages and returns the assistant text.
-	Chat(ctx context.Context, messages []Message, opts ...RequestOption) (string, error)
+    // Chat sends chat messages and returns the assistant text.
+    Chat(ctx context.Context, messages []Message, opts ...RequestOption) (string, error)
 }
 
 // Options for a request. Providers may ignore unsupported fields.
@@ -41,9 +41,23 @@ func WithStop(stop ...string) RequestOption {
 // NewDefault returns the default provider using environment configuration.
 // Currently this is the OpenAI provider using OPENAI_API_KEY.
 func NewDefault(logger *log.Logger) (Client, error) {
-	apiKey := os.Getenv("OPENAI_API_KEY")
-	if apiKey == "" {
-		return nil, errors.New("OPENAI_API_KEY is not set")
-	}
-	return newOpenAIFromEnv(apiKey, logger), nil
+    apiKey := os.Getenv("OPENAI_API_KEY")
+    if apiKey == "" {
+        return nil, errors.New("OPENAI_API_KEY is not set")
+    }
+    return newOpenAIFromEnv(apiKey, logger), nil
+}
+
+// Logging configuration for previews
+var logPreviewLimit int // 0 means unlimited
+
+// SetLogPreviewLimit sets the maximum number of characters to log for
+// request/response previews. Set to 0 for unlimited.
+func SetLogPreviewLimit(n int) { logPreviewLimit = n }
+
+func previewForLog(s string) string {
+    if logPreviewLimit > 0 {
+        return trimPreview(s, logPreviewLimit)
+    }
+    return s
 }