From 8a53cb96651fad13c665417aadbedddf3e14a284 Mon Sep 17 00:00:00 2001
From: Chujiang <110hqc@gmail.com>
Date: Tue, 24 Feb 2026 05:52:16 +0800
Subject: [PATCH] fix: align Docker Go version with go.mod and optimize logger
 (#596)

- Update Dockerfile to use golang:1.25-alpine to match go.mod (go 1.25.7)
- Optimize logger by avoiding string concatenation in file writes
- Add explicit empty string assignment for fieldStr when no fields

These changes improve build consistency and reduce memory allocations
in the hot logging path, which is important for the project's goal
of running on resource-constrained devices (<10MB RAM).

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 Dockerfile           | 2 +-
 pkg/logger/logger.go | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index 0360cfda6..480244127 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,7 +1,7 @@
 # ============================================================
 # Stage 1: Build the picoclaw binary
 # ============================================================
-FROM golang:1.26.0-alpine AS builder
+FROM golang:1.25-alpine AS builder
 
 RUN apk add --no-cache git make
 
diff --git a/pkg/logger/logger.go b/pkg/logger/logger.go
index 54de66bf9..c14fbd464 100644
--- a/pkg/logger/logger.go
+++ b/pkg/logger/logger.go
@@ -119,13 +119,15 @@ func logMessage(level LogLevel, component string, message string, fields map[str
 	if logger.file != nil {
 		jsonData, err := json.Marshal(entry)
 		if err == nil {
-			logger.file.WriteString(string(jsonData) + "\n")
+			logger.file.Write(append(jsonData, '\n'))
 		}
 	}
 
 	var fieldStr string
 	if len(fields) > 0 {
 		fieldStr = " " + formatFields(fields)
+	} else {
+		fieldStr = ""
 	}
 
 	logLine := fmt.Sprintf("[%s] [%s]%s %s%s",