chore: Upgrade to go 1.26 (#1655)

Author: yottahmd

.github/workflows/ci.yaml

@@ -27,7 +27,7 @@ on:
       - ".github/workflows/ci.yaml"
 
 env:
-  GO_VERSION: "1.25"
+  GO_VERSION: "1.26"
 
 jobs:
   # Spell check
@@ -58,12 +58,21 @@ jobs:
         run: |
           go fmt ./...
           # Fail if formatting changed any files
-          git diff --exit-code || (echo "Go files are not formatted. Please run 'go fmt ./...'" && exit 1)
+          git diff --exit-code || (echo "Go files are not formatted. Please run 'make fmt'" && exit 1)
+
+      - name: Check modernize (go fix)
+        run: |
+          diff=$(go fix -diff ./... 2>&1) || true
+          if [ -n "$diff" ]; then
+            echo "Go files need modernization. Please run 'make fmt'"
+            echo "$diff"
+            exit 1
+          fi
 
       - name: Run golangci-lint
         uses: golangci/golangci-lint-action@v9
         with:
-          version: v2.5.0
+          version: v2.9.0
           args: --timeout=10m
 
   # Test Go code on multiple platforms

Dockerfile

@@ -13,7 +13,7 @@ RUN rm -rf node_modules; \
   pnpm build
 
 # Stage 2: Go Builder
-FROM --platform=$TARGETPLATFORM golang:1.25-alpine AS go-builder
+FROM --platform=$TARGETPLATFORM golang:1.26-alpine AS go-builder
 ARG LDFLAGS
 ARG TARGETOS
 ARG TARGETARCH

Dockerfile.alpine

@@ -13,7 +13,7 @@ RUN rm -rf node_modules; \
   pnpm build
 
 # Stage 2: Go Builder
-FROM --platform=$TARGETPLATFORM golang:1.25-alpine AS go-builder
+FROM --platform=$TARGETPLATFORM golang:1.26-alpine AS go-builder
 ARG LDFLAGS
 ARG TARGETOS
 ARG TARGETARCH

Dockerfile.dev

@@ -13,7 +13,7 @@ RUN rm -rf node_modules; \
   pnpm build
 
 # Stage 2: Go Builder
-FROM --platform=$TARGETPLATFORM golang:1.25-alpine AS go-builder
+FROM --platform=$TARGETPLATFORM golang:1.26-alpine AS go-builder
 ARG LDFLAGS
 ARG TARGETOS
 ARG TARGETARCH

Makefile

@@ -353,6 +353,30 @@ clean-ui:
 		rm -rf node_modules; \
 		rm -rf .cache;
 
+# fmt auto-fixes all code style issues (go fix + go fmt + linter --fix).
+# AI agents and developers should run this before committing.
+.PHONY: fmt
+fmt:
+	@echo "${COLOR_GREEN}Running go fix...${COLOR_RESET}"
+	@go fix ./...
+	@echo "${COLOR_GREEN}Running go fmt...${COLOR_RESET}"
+	@go fmt ./...
+	@echo "${COLOR_GREEN}Running linter with --fix...${COLOR_RESET}"
+	@GOBIN=${LOCAL_BIN_DIR} go install $(PKG_golangci_lint)
+	@${LOCAL_BIN_DIR}/golangci-lint run --fix ./...
+
+# check verifies code style without modifying files (for CI).
+.PHONY: check
+check:
+	@echo "${COLOR_GREEN}Checking go fix...${COLOR_RESET}"
+	@diff=$$(go fix -diff ./... 2>&1); if [ -n "$$diff" ]; then echo "$$diff"; echo "${COLOR_RED}Run 'make fmt'${COLOR_RESET}"; exit 1; fi
+	@echo "${COLOR_GREEN}Checking go fmt...${COLOR_RESET}"
+	@go fmt ./...
+	@git diff --exit-code || (echo "${COLOR_RED}Run 'make fmt'${COLOR_RESET}" && exit 1)
+	@echo "${COLOR_GREEN}Running linter...${COLOR_RESET}"
+	@GOBIN=${LOCAL_BIN_DIR} go install $(PKG_golangci_lint)
+	@${LOCAL_BIN_DIR}/golangci-lint run --timeout=10m ./...
+
 # golangci-lint run linting tool.
 .PHONY: golangci-lint
 golangci-lint:

deploy/docker/Dockerfile.alpine

@@ -13,7 +13,7 @@ RUN rm -rf node_modules; \
   pnpm build
 
 # Stage 2: Go Builder
-FROM --platform=$TARGETPLATFORM golang:1.25-alpine AS go-builder
+FROM --platform=$TARGETPLATFORM golang:1.26-alpine AS go-builder
 ARG LDFLAGS
 ARG TARGETOS
 ARG TARGETARCH

deploy/docker/Dockerfile.dev

@@ -13,7 +13,7 @@ RUN rm -rf node_modules; \
   pnpm build
 
 # Stage 2: Go Builder
-FROM --platform=$TARGETPLATFORM golang:1.25-alpine AS go-builder
+FROM --platform=$TARGETPLATFORM golang:1.26-alpine AS go-builder
 ARG LDFLAGS
 ARG TARGETOS
 ARG TARGETARCH

go.mod

@@ -1,6 +1,6 @@
 module github.com/dagu-org/dagu
 
-go 1.25.5
+go 1.26
 
 require (
 	dario.cat/mergo v1.0.2

internal/agent/api.go

@@ -453,7 +453,7 @@ func (a *API) handleGetSession(w http.ResponseWriter, r *http.Request) {
 	if mgr, ok := a.getActiveSession(id, userID); ok {
 		a.respondJSON(w, http.StatusOK, StreamResponse{
 			Messages: mgr.GetMessages(),
-			Session:  ptrTo(mgr.GetSession()),
+			Session:  new(mgr.GetSession()),
 			SessionState: &SessionState{
 				SessionID: id,
 				Working:   mgr.IsWorking(),
@@ -806,8 +806,3 @@ func (a *API) cleanupIdleSessions() {
 		a.logger.Debug("Cleaned up idle session", "session_id", id)
 	}
 }
-
-// ptrTo returns a pointer to the given value.
-func ptrTo[T any](v T) *T {
-	return &v
-}

internal/agent/patch_test.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"github.com/dagu-org/dagu/internal/core"
@@ -24,11 +25,12 @@ func TestMain(m *testing.M) {
 }
 
 func patchInput(path, operation string, extra ...string) json.RawMessage {
-	base := fmt.Sprintf(`{"path": %q, "operation": %q`, path, operation)
+	var base strings.Builder
+	base.WriteString(fmt.Sprintf(`{"path": %q, "operation": %q`, path, operation))
 	for i := 0; i < len(extra)-1; i += 2 {
-		base += fmt.Sprintf(`, %q: %q`, extra[i], extra[i+1])
+		base.WriteString(fmt.Sprintf(`, %q: %q`, extra[i], extra[i+1]))
 	}
-	return json.RawMessage(base + "}")
+	return json.RawMessage(base.String() + "}")
 }
 
 func TestPatchTool_Create(t *testing.T) {