feat(go): added support for embedding prompts into the binary (#3973)

Author: apascal07

go/ai/prompt.go

@@ -19,11 +19,12 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io/fs"
 	"iter"
 	"log/slog"
 	"maps"
 	"os"
-	"path/filepath"
+	"path"
 	"reflect"
 	"slices"
 	"strings"
@@ -601,87 +602,84 @@ func convertToPartPointers(parts []dotprompt.Part) ([]*Part, error) {
 	return result, nil
 }
 
-// LoadPromptDir loads prompts and partials from the input directory for the given namespace.
-func LoadPromptDir(r api.Registry, dir string, namespace string) {
-	useDefaultDir := false
-	if dir == "" {
-		dir = "./prompts"
-		useDefaultDir = true
+// LoadPromptDirFromFS loads prompts and partials from a filesystem for the given namespace.
+// The fsys parameter should be an fs.FS implementation (e.g., embed.FS or os.DirFS).
+// The dir parameter specifies the directory within the filesystem where prompts are located.
+func LoadPromptDirFromFS(r api.Registry, fsys fs.FS, dir, namespace string) {
+	if fsys == nil {
+		panic(errors.New("no prompt filesystem provided"))
 	}
 
-	path, err := filepath.Abs(dir)
-	if err != nil {
-		if !useDefaultDir {
-			panic(fmt.Errorf("failed to resolve prompt directory %q: %w", dir, err))
-		}
-		slog.Debug("default prompt directory not found, skipping loading .prompt files", "dir", dir)
-		return
+	if _, err := fs.Stat(fsys, dir); err != nil {
+		panic(fmt.Errorf("failed to access prompt directory %q in filesystem: %w", dir, err))
 	}
 
-	if _, err := os.Stat(path); os.IsNotExist(err) {
-		if !useDefaultDir {
-			panic(fmt.Errorf("failed to resolve prompt directory %q: %w", dir, err))
-		}
-		slog.Debug("Default prompt directory not found, skipping loading .prompt files", "dir", dir)
-		return
-	}
-
-	loadPromptDir(r, path, namespace)
-}
-
-// loadPromptDir recursively loads prompts and partials from the directory.
-func loadPromptDir(r api.Registry, dir string, namespace string) {
-	entries, err := os.ReadDir(dir)
+	entries, err := fs.ReadDir(fsys, dir)
 	if err != nil {
 		panic(fmt.Errorf("failed to read prompt directory structure: %w", err))
 	}
 
 	for _, entry := range entries {
 		filename := entry.Name()
-		path := filepath.Join(dir, filename)
+		filePath := path.Join(dir, filename)
 		if entry.IsDir() {
-			loadPromptDir(r, path, namespace)
+			LoadPromptDirFromFS(r, fsys, filePath, namespace)
 		} else if strings.HasSuffix(filename, ".prompt") {
 			if strings.HasPrefix(filename, "_") {
 				partialName := strings.TrimSuffix(filename[1:], ".prompt")
-				source, err := os.ReadFile(path)
+				source, err := fs.ReadFile(fsys, filePath)
 				if err != nil {
 					slog.Error("Failed to read partial file", "error", err)
 					continue
 				}
 				r.RegisterPartial(partialName, string(source))
-				slog.Debug("Registered Dotprompt partial", "name", partialName, "file", path)
+				slog.Debug("Registered Dotprompt partial", "name", partialName, "file", filePath)
 			} else {
-				LoadPrompt(r, dir, filename, namespace)
+				LoadPromptFromFS(r, fsys, dir, filename, namespace)
 			}
 		}
 	}
 }
 
-// LoadPrompt loads a single prompt into the registry.
-func LoadPrompt(r api.Registry, dir, filename, namespace string) Prompt {
+// LoadPromptFromFS loads a single prompt from a filesystem into the registry.
+// The fsys parameter should be an fs.FS implementation (e.g., embed.FS or os.DirFS).
+// The dir parameter specifies the directory within the filesystem where the prompt is located.
+func LoadPromptFromFS(r api.Registry, fsys fs.FS, dir, filename, namespace string) Prompt {
 	name := strings.TrimSuffix(filename, ".prompt")
-	name, variant, _ := strings.Cut(name, ".")
 
-	sourceFile := filepath.Join(dir, filename)
-	source, err := os.ReadFile(sourceFile)
+	sourceFile := path.Join(dir, filename)
+	source, err := fs.ReadFile(fsys, sourceFile)
 	if err != nil {
 		slog.Error("Failed to read prompt file", "file", sourceFile, "error", err)
 		return nil
 	}
 
+	p, err := LoadPromptFromSource(r, string(source), name, namespace)
+	if err != nil {
+		slog.Error("Failed to load prompt", "file", sourceFile, "error", err)
+		return nil
+	}
+
+	slog.Debug("Registered Dotprompt", "name", p.Name(), "file", sourceFile)
+	return p
+}
+
+// LoadPromptFromSource loads a prompt from raw .prompt file content.
+// The source parameter should contain the complete .prompt file text (frontmatter + template).
+// The name parameter is the prompt name (may include variant suffix like "myPrompt.variant").
+func LoadPromptFromSource(r api.Registry, source, name, namespace string) (Prompt, error) {
+	name, variant, _ := strings.Cut(name, ".")
+
 	dp := r.Dotprompt()
 
-	parsedPrompt, err := dp.Parse(string(source))
+	parsedPrompt, err := dp.Parse(source)
 	if err != nil {
-		slog.Error("Failed to parse file as dotprompt", "file", sourceFile, "error", err)
-		return nil
+		return nil, fmt.Errorf("failed to parse dotprompt: %w", err)
 	}
 
-	metadata, err := dp.RenderMetadata(string(source), &parsedPrompt.PromptMetadata)
+	metadata, err := dp.RenderMetadata(source, &parsedPrompt.PromptMetadata)
 	if err != nil {
-		slog.Error("Failed to render dotprompt metadata", "file", sourceFile, "error", err)
-		return nil
+		return nil, fmt.Errorf("failed to render dotprompt metadata: %w", err)
 	}
 
 	toolRefs := make([]ToolRef, len(metadata.Tools))
@@ -765,17 +763,15 @@ func LoadPrompt(r api.Registry, dir, filename, namespace string) Prompt {
 
 	dpMessages, err := dotprompt.ToMessages(parsedPrompt.Template, &dotprompt.DataArgument{})
 	if err != nil {
-		slog.Error("Failed to convert prompt template to messages", "file", sourceFile, "error", err)
-		return nil
+		return nil, fmt.Errorf("failed to convert prompt template to messages: %w", err)
 	}
 
 	var systemText string
 	var nonSystemMessages []*Message
 	for _, dpMsg := range dpMessages {
 		parts, err := convertToPartPointers(dpMsg.Content)
 		if err != nil {
-			slog.Error("Failed to convert message parts", "file", sourceFile, "error", err)
-			return nil
+			return nil, fmt.Errorf("failed to convert message parts: %w", err)
 		}
 
 		role := Role(dpMsg.Role)
@@ -809,9 +805,17 @@ func LoadPrompt(r api.Registry, dir, filename, namespace string) Prompt {
 
 	prompt := DefinePrompt(r, key, promptOpts...)
 
-	slog.Debug("Registered Dotprompt", "name", key, "file", sourceFile)
+	return prompt, nil
+}
 
-	return prompt
+// LoadPromptDir loads prompts and partials from a directory on the local filesystem.
+func LoadPromptDir(r api.Registry, dir string, namespace string) {
+	LoadPromptDirFromFS(r, os.DirFS(dir), ".", namespace)
+}
+
+// LoadPrompt loads a single prompt from a directory on the local filesystem into the registry.
+func LoadPrompt(r api.Registry, dir, filename, namespace string) Prompt {
+	return LoadPromptFromFS(r, os.DirFS(dir), ".", filename, namespace)
 }
 
 // promptKey generates a unique key for the prompt in the registry.