Issue when compiling static files

[gopherine]

So I have been trying to run htmx and have this project structure, this does work when all of these three files i.e main.go static_prod.go and static_dev.go is in root of the project alongside embed.go but with below structure it does not work

cmd/app
    main.go
    static_prod.go
    static_dev.go
embed.go

---

// embed.go
package static

import "embed"

//go:embed public/**/*
var PublicFS embed.FS

// static_prod.go
//go:build !dev
// +build !dev

package main

import (
	"net/http"

	static "github.com/goemon"
)

func public() http.Handler {
	return http.FileServerFS(static.PublicFS)
}

static_dev.go

//go:build dev
// +build dev

package main

import (
	"fmt"
	"net/http"
	"os"
)

func public() http.Handler {
	fmt.Println("Building static files for development")
	return http.StripPrefix("../public/**/*", http.FileServerFS(os.DirFS("public")))
}

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"time"

	static "github.com/goemon"
	"github.com/goemon/internals/handlers"
	"github.com/joho/godotenv"
	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
)

func main() {
	if err := godotenv.Load(); err != nil {
		log.Fatal(err)
	}

	// Echo instance
	e := echo.New()

	e.GET("/", func(c echo.Context) error {
		time.Sleep(5 * time.Second)
		return c.JSON(http.StatusOK, "OK")
	})

	// Middleware
	e.Use(middleware.Logger())
	e.Use(middleware.Recover())

	// Routes
	e.GET("/*", echo.WrapHandler(http.FileServer(http.FS(static.PublicFS))))
	e.GET("/", handlers.Make(handlers.Hello))

	// Start server
	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
	defer stop()
	// Start server
	go func() {
		if err := e.Start(fmt.Sprintf(":%s", os.Getenv("LISTEN_ADDR"))); err != nil && err != http.ErrServerClosed {
			e.Logger.Fatal("shutting down the server")
		}
	}()

	// Wait for interrupt signal to gracefully shutdown the server with a timeout of 10 seconds.
	<-ctx.Done()
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	if err := e.Shutdown(ctx); err != nil {
		e.Logger.Fatal(err)
	}
}

Now this works perfectly fine when building and running it manually

however with air it does not work

1. initially it asks for permissions to tmp folder
2. once i set permission via chmod , I get below error

Now, I could understand the error could be in code but this works perfectly fine when building and running it manually

/Users/arvee/Documents/interview/amm-ui/goemx/tmp/main: line 1: syntax error near unexpected token `newline'
/Users/arvee/Documents/interview/amm-ui/goemx/tmp/main: line 1: `!<arch>'

root = "."
testdata_dir = "testdata"
tmp_dir = "tmp"

[build]
args_bin = []
bin = "./tmp/main"
cmd = "go build -tags '!dev' -o tmp/main ./cmd/app/."

delay = 1000
exclude_dir = ["assets", "tmp", "vendor", "testdata", "node_modules"]
exclude_file = []
exclude_regex = ["_test.go"]
exclude_unchanged = false
follow_symlink = false
full_bin = ""
include_dir = []
include_ext = ["go", "tpl", "tmpl", "templ", "html"]
kill_delay = "0s"
log = "build-errors.log"
send_interrupt = false
stop_on_error = true

[color]
app = ""
build = "yellow"
main = "magenta"
runner = "green"
watcher = "blue"

[log]
time = false

[misc]
clean_on_exit = false

[screen]
clear_on_rebuild = false