feat(build): introduce build configuration for channel inclusion

- Add `build.yaml.example` for configuring which channels to compile into the binary.
- Implement `genbuild` script to generate channel imports based on `build.yaml`.
- Update `Makefile` to run `genbuild` automatically during the build process.
- Create documentation in `BUILD_CONFIG.md` to guide users on configuring and using the build system.
- Move channel imports to `channels_imports.go`, generated by `genbuild`, to reduce binary size.

Makefile

@@ -72,8 +72,13 @@ BINARY_PATH=$(BUILD_DIR)/$(BINARY_NAME)-$(PLATFORM)-$(ARCH)
 # Default target
 all: build
 
-## generate: Run generate
-generate:
+## genbuild: Generate channel imports from build.yaml (channels.include). Run before build to shrink binary.
+genbuild:
+	@echo "Generating channel imports from build.yaml..."
+	@$(GO) run ./scripts/genbuild
+
+## generate: Run genbuild and go generate
+generate: genbuild
 	@echo "Run generate..."
 	@rm -r ./$(CMD_DIR)/workspace 2>/dev/null || true
 	@$(GO) generate ./...

build.yaml.example

@@ -0,0 +1,17 @@
+# Build configuration: control which channels (and optionally providers/tools in the future)
+# are compiled into the binary to reduce size. Copy to build.yaml and edit. Used when you run:
+#   make build
+# (or run: go run ./scripts/genbuild before go build).
+#
+# See docs/BUILD_CONFIG.md.
+
+channels:
+  # Preferred allowlist model: list the channel names you want to include.
+  # If empty or omitted, all discovered channels under pkg/channels/ are included.
+  #
+  # Channel names must match the channel package directory under pkg/channels/.
+  include: []
+  # include: [telegram, whatsapp, discord, slack, feishu, dingtalk, wecom, qq, line, onebot, maixcam, pico, whatsapp_native]
+
+  # Optional denylist model:
+  #   skip: [telegram, whatsapp]

cmd/picoclaw/internal/gateway/channels_imports.go

@@ -0,0 +1,20 @@
+// Code generated by scripts/genbuild. DO NOT EDIT.
+// Edit build.yaml and run: go run ./scripts/genbuild (or make build).
+
+package gateway
+
+import (
+	_ "github.com/sipeed/picoclaw/pkg/channels/dingtalk"
+	_ "github.com/sipeed/picoclaw/pkg/channels/discord"
+	_ "github.com/sipeed/picoclaw/pkg/channels/feishu"
+	_ "github.com/sipeed/picoclaw/pkg/channels/line"
+	_ "github.com/sipeed/picoclaw/pkg/channels/maixcam"
+	_ "github.com/sipeed/picoclaw/pkg/channels/onebot"
+	_ "github.com/sipeed/picoclaw/pkg/channels/pico"
+	_ "github.com/sipeed/picoclaw/pkg/channels/qq"
+	_ "github.com/sipeed/picoclaw/pkg/channels/slack"
+	_ "github.com/sipeed/picoclaw/pkg/channels/telegram"
+	_ "github.com/sipeed/picoclaw/pkg/channels/wecom"
+	_ "github.com/sipeed/picoclaw/pkg/channels/whatsapp"
+	_ "github.com/sipeed/picoclaw/pkg/channels/whatsapp_native"
+)

cmd/picoclaw/internal/gateway/helpers.go

@@ -13,19 +13,7 @@ import (
 	"github.com/sipeed/picoclaw/pkg/agent"
 	"github.com/sipeed/picoclaw/pkg/bus"
 	"github.com/sipeed/picoclaw/pkg/channels"
-	_ "github.com/sipeed/picoclaw/pkg/channels/dingtalk"
-	_ "github.com/sipeed/picoclaw/pkg/channels/discord"
-	_ "github.com/sipeed/picoclaw/pkg/channels/feishu"
-	_ "github.com/sipeed/picoclaw/pkg/channels/line"
-	_ "github.com/sipeed/picoclaw/pkg/channels/maixcam"
-	_ "github.com/sipeed/picoclaw/pkg/channels/onebot"
-	_ "github.com/sipeed/picoclaw/pkg/channels/pico"
-	_ "github.com/sipeed/picoclaw/pkg/channels/qq"
-	_ "github.com/sipeed/picoclaw/pkg/channels/slack"
-	_ "github.com/sipeed/picoclaw/pkg/channels/telegram"
-	_ "github.com/sipeed/picoclaw/pkg/channels/wecom"
-	_ "github.com/sipeed/picoclaw/pkg/channels/whatsapp"
-	_ "github.com/sipeed/picoclaw/pkg/channels/whatsapp_native"
+	// Channel imports are in channels_imports.go (generated by scripts/genbuild from build.yaml).
 	"github.com/sipeed/picoclaw/pkg/config"
 	"github.com/sipeed/picoclaw/pkg/cron"
 	"github.com/sipeed/picoclaw/pkg/devices"

docs/BUILD_CONFIG.md

@@ -0,0 +1,45 @@
+## Build configuration (optional smaller binary)
+
+You can control **which channels are compiled into the binary** to reduce size. This is done **before** the build by parsing a config file and generating which channel packages get compiled in.
+
+### How it works
+
+1. **Config**: Create `build.yaml` in the repo root (copy from `build.yaml.example`).
+2. **Allowlist**: Set `channels.include` to the channel names you want to compile in (e.g. `[telegram, whatsapp]`).
+3. **Generate**: Run the generator so it writes `cmd/picoclaw/internal/gateway/channels_imports.go` with only the selected channel imports.
+4. **Build**: Run `make build`. The generator is run automatically as part of `make build`.
+
+If there is no `build.yaml`, or `channels.include` is empty / omitted, **all discovered channels** under `pkg/channels/` are included by default.
+
+### Quick start
+
+```bash
+# Copy example and edit (list channels to include)
+cp build.yaml.example build.yaml
+
+# Edit build.yaml, e.g.:
+#   channels:
+#     include: [telegram, whatsapp]
+
+# Build (generate runs first and overwrites channel imports)
+make build
+```
+
+Or without Make:
+
+```bash
+go run ./scripts/genbuild   # generate channel imports from build.yaml
+go build -o picoclaw ./cmd/picoclaw
+```
+
+### Channel names
+
+Channel names in `channels.include` must match the directory name under `pkg/channels/`. The generator **automatically discovers** all channel packages by reading the `pkg/channels/` directory, so you usually don't need to touch any code when adding a new channel—just create `pkg/channels/<name>/` and, if desired, list `<name>` in `channels.include`.
+
+
+
+Optional denylist options also work:
+
+- `channels.skip: [telegram, whatsapp]`
+
+If `channels.include` is set, it **wins** over any skip settings.

scripts/genbuild/main.go

@@ -0,0 +1,200 @@
+// genbuild reads build.yaml (channels.include) and
+// generates cmd/picoclaw/internal/gateway/channels_imports.go so only the
+// selected channels are compiled in, reducing binary size.
+//
+// Run before build: go run ./scripts/genbuild
+// Or use: make build (which runs this via the generate target).
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+const (
+	buildConfigName = "build.yaml"
+	outputPath      = "cmd/picoclaw/internal/gateway/channels_imports.go"
+	modulePath      = "github.com/sipeed/picoclaw"
+)
+
+type buildConfig struct {
+	// Preferred allowlist model:
+	//   channels:
+	//     include: [telegram, whatsapp]
+	// Optional denylist model:
+	//   channels:
+	//     skip: [telegram, whatsapp]
+	Channels struct {
+		Include []string `yaml:"include"`
+		Skip    []string `yaml:"skip"`
+	} `yaml:"channels"`
+}
+
+func main() {
+	repoRoot, err := findRepoRoot()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "genbuild: %v\n", err)
+		os.Exit(1)
+	}
+
+	cfg := loadConfig(repoRoot)
+
+	allChannels, err := discoverChannels(repoRoot)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "genbuild: discover channels: %v\n", err)
+		os.Exit(1)
+	}
+
+	include := selectChannels(allChannels, cfg)
+
+	outPath := filepath.Join(repoRoot, outputPath)
+	if err := os.MkdirAll(filepath.Dir(outPath), 0o755); err != nil {
+		fmt.Fprintf(os.Stderr, "genbuild: %v\n", err)
+		os.Exit(1)
+	}
+
+	content := generateImports(include)
+	if err := os.WriteFile(outPath, []byte(content), 0o644); err != nil {
+		fmt.Fprintf(os.Stderr, "genbuild: %v\n", err)
+		os.Exit(1)
+	}
+
+	fmt.Fprintf(os.Stderr, "genbuild: wrote %s (%d channels)\n", outputPath, len(include))
+}
+
+func findRepoRoot() (string, error) {
+	dir, err := os.Getwd()
+	if err != nil {
+		return "", err
+	}
+	for {
+		if _, err := os.Stat(filepath.Join(dir, "go.mod")); err == nil {
+			return dir, nil
+		}
+		parent := filepath.Dir(dir)
+		if parent == dir {
+			return "", fmt.Errorf("go.mod not found (run from repo root)")
+		}
+		dir = parent
+	}
+}
+
+func loadConfig(repoRoot string) *buildConfig {
+	cfg := &buildConfig{}
+	path := filepath.Join(repoRoot, buildConfigName)
+	data, err := os.ReadFile(path)
+	if err != nil {
+		// No build.yaml: include all channels
+		return cfg
+	}
+	if err := yaml.Unmarshal(data, cfg); err != nil {
+		fmt.Fprintf(os.Stderr, "genbuild: warning: %s: %v (including all channels)\n", path, err)
+		return cfg
+	}
+	return cfg
+}
+
+// discoverChannels returns all channel package names (directory names under pkg/channels/).
+func discoverChannels(repoRoot string) ([]string, error) {
+	dir := filepath.Join(repoRoot, "pkg", "channels")
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return nil, err
+	}
+
+	var channels []string
+	for _, e := range entries {
+		if !e.IsDir() {
+			continue
+		}
+		name := e.Name()
+		if strings.HasPrefix(name, ".") || strings.HasPrefix(name, "_") {
+			continue
+		}
+		channels = append(channels, name)
+	}
+
+	sort.Strings(channels)
+	return channels, nil
+}
+
+// selectChannels applies the config to the discovered channels, preferring the
+// allowlist model (channels.include), and optionally the denylist model (channels.skip).
+func selectChannels(all []string, cfg *buildConfig) []string {
+	if len(all) == 0 {
+		return nil
+	}
+
+	available := make(map[string]struct{}, len(all))
+	for _, ch := range all {
+		available[ch] = struct{}{}
+	}
+
+	// 1) Preferred allowlist: channels.include
+	if len(cfg.Channels.Include) > 0 {
+		var include []string
+		for _, raw := range cfg.Channels.Include {
+			name := strings.TrimSpace(raw)
+			if name == "" {
+				continue
+			}
+			if _, ok := available[name]; !ok {
+				fmt.Fprintf(os.Stderr, "genbuild: warning: channel %q listed in channels.include but no such pkg/channels/%s\n", name, name)
+				continue
+			}
+			include = append(include, name)
+		}
+		if len(include) == 0 {
+			// Nothing matched; fall back to "all" to avoid surprising empty builds.
+			return all
+		}
+		sort.Strings(include)
+		return include
+	}
+
+	// 2) denylist: channels.skip.
+	skipSet := make(map[string]struct{})
+	for _, raw := range cfg.Channels.Skip {
+		name := strings.TrimSpace(raw)
+		if name == "" {
+			continue
+		}
+		skipSet[name] = struct{}{}
+	}
+
+	if len(skipSet) == 0 {
+		// No config at all or no skip entries: include all channels.
+		return all
+	}
+
+	var include []string
+	for _, ch := range all {
+		if _, skip := skipSet[ch]; skip {
+			continue
+		}
+		include = append(include, ch)
+	}
+	return include
+}
+
+func generateImports(channels []string) string {
+	var b strings.Builder
+	b.WriteString("// Code generated by scripts/genbuild. DO NOT EDIT.\n")
+	b.WriteString("// Edit build.yaml and run: go run ./scripts/genbuild (or make build).\n\n")
+	b.WriteString("package gateway\n\n")
+	b.WriteString("import (\n")
+	for _, ch := range channels {
+		b.WriteString("\t_ \"")
+		b.WriteString(modulePath)
+		b.WriteString("/pkg/channels/")
+		b.WriteString(ch)
+		b.WriteString("\"\n")
+	}
+	b.WriteString(")\n")
+	return b.String()
+}