Support multiple variables in run

cmd/run/run.go

@@ -204,10 +204,16 @@ func NewRunCommand(cfg *command.Config) *cobra.Command {
 			If you know which model you want to run inference with, you can run the request in a single command
 			as %[1]sgh models run [model] [prompt]%[1]s
 
+			When using prompt files, you can pass template variables using the %[1]s--var%[1]s flag:
+			%[1]sgh models run --file prompt.yml --var name=Alice --var topic=AI%[1]s
+
 			The return value will be the response to your prompt from the selected model.
 		`, "`"),
-		Example: "gh models run openai/gpt-4o-mini \"how many types of hyena are there?\"",
-		Args:    cobra.ArbitraryArgs,
+		Example: heredoc.Doc(`
+			gh models run openai/gpt-4o-mini "how many types of hyena are there?"
+			gh models run --file prompt.yml --var name=Alice --var topic="machine learning"
+		`),
+		Args: cobra.ArbitraryArgs,
 		RunE: func(cmd *cobra.Command, args []string) error {
 			filePath, _ := cmd.Flags().GetString("file")
 			var pf *prompt.File
@@ -223,6 +229,12 @@ func NewRunCommand(cfg *command.Config) *cobra.Command {
 				}
 			}
 
+			// Parse template variables from flags
+			templateVars, err := parseTemplateVariables(cmd.Flags())
+			if err != nil {
+				return err
+			}
+
 			cmdHandler := newRunCommandHandler(cmd, cfg, args)
 			if cmdHandler == nil {
 				return nil
@@ -270,16 +282,22 @@ func NewRunCommand(cfg *command.Config) *cobra.Command {
 			}
 
 			// If there is no prompt file, add the initialPrompt to the conversation.
-			// If a prompt file is passed, load the messages from the file, templating {{input}}
-			// using the initialPrompt.
+			// If a prompt file is passed, load the messages from the file, templating variables
+			// using the provided template variables and initialPrompt.
 			if pf == nil {
 				conversation.AddMessage(azuremodels.ChatMessageRoleUser, initialPrompt)
 			} else {
 				interactiveMode = false
 
-				// Template the messages with the input
-				templateData := map[string]interface{}{
-					"input": initialPrompt,
+				// Template the messages with the variables
+				templateData := make(map[string]interface{})
+
+				// Add the input variable (backward compatibility)
+				templateData["input"] = initialPrompt
+
+				// Add custom variables
+				for key, value := range templateVars {
+					templateData[key] = value
 				}
 
 				for _, m := range pf.Messages {
@@ -385,6 +403,7 @@ func NewRunCommand(cfg *command.Config) *cobra.Command {
 	}
 
 	cmd.Flags().String("file", "", "Path to a .prompt.yml file.")
+	cmd.Flags().StringSlice("var", []string{}, "Template variables for prompt files (can be used multiple times: --var name=value)")
 	cmd.Flags().String("max-tokens", "", "Limit the maximum tokens for the model response.")
 	cmd.Flags().String("temperature", "", "Controls randomness in the response, use lower to be more deterministic.")
 	cmd.Flags().String("top-p", "", "Controls text diversity by selecting the most probable words until a set probability is reached.")
@@ -393,6 +412,43 @@ func NewRunCommand(cfg *command.Config) *cobra.Command {
 	return cmd
 }
 
+// parseTemplateVariables parses template variables from the --var flags
+func parseTemplateVariables(flags *pflag.FlagSet) (map[string]string, error) {
+	varFlags, err := flags.GetStringSlice("var")
+	if err != nil {
+		return nil, err
+	}
+
+	templateVars := make(map[string]string)
+	for _, varFlag := range varFlags {
+		// Handle empty strings
+		if strings.TrimSpace(varFlag) == "" {
+			continue
+		}
+
+		parts := strings.SplitN(varFlag, "=", 2)
+		if len(parts) != 2 {
+			return nil, fmt.Errorf("invalid variable format '%s', expected 'key=value'", varFlag)
+		}
+
+		key := strings.TrimSpace(parts[0])
+		value := parts[1] // Don't trim value to preserve intentional whitespace
+
+		if key == "" {
+			return nil, fmt.Errorf("variable key cannot be empty in '%s'", varFlag)
+		}
+
+		// Check for duplicate keys
+		if _, exists := templateVars[key]; exists {
+			return nil, fmt.Errorf("duplicate variable key '%s'", key)
+		}
+
+		templateVars[key] = value
+	}
+
+	return templateVars, nil
+}
+
 type runCommandHandler struct {
 	ctx    context.Context
 	cfg    *command.Config
@@ -445,7 +501,7 @@ func (h *runCommandHandler) getModelNameFromArgs(models []*azuremodels.ModelSumm
 }
 
 func validateModelName(modelName string, models []*azuremodels.ModelSummary) (string, error) {
-	noMatchErrorMessage := "The specified model name is not found. Run 'gh models list' to see available models or 'gh models run' to select interactively."
+	noMatchErrorMessage := fmt.Sprintf("The specified model '%s' is not found. Run 'gh models list' to see available models or 'gh models run' to select interactively.", modelName)
 
 	if modelName == "" {
 		return "", errors.New(noMatchErrorMessage)

cmd/run/run_test.go

@@ -11,6 +11,7 @@ import (
 	"github.com/github/gh-models/internal/sse"
 	"github.com/github/gh-models/pkg/command"
 	"github.com/github/gh-models/pkg/util"
+	"github.com/spf13/pflag"
 	"github.com/stretchr/testify/require"
 )
 
@@ -331,3 +332,74 @@ messages:
 		require.Equal(t, "User message", *capturedReq.Messages[1].Content)
 	})
 }
+
+func TestParseTemplateVariables(t *testing.T) {
+	tests := []struct {
+		name      string
+		varFlags  []string
+		expected  map[string]string
+		expectErr bool
+	}{
+		{
+			name:     "empty vars",
+			varFlags: []string{},
+			expected: map[string]string{},
+		},
+		{
+			name:     "single var",
+			varFlags: []string{"name=John"},
+			expected: map[string]string{"name": "John"},
+		},
+		{
+			name:     "multiple vars",
+			varFlags: []string{"name=John", "age=25", "city=New York"},
+			expected: map[string]string{"name": "John", "age": "25", "city": "New York"},
+		},
+		{
+			name:     "multi-word values",
+			varFlags: []string{"full_name=John Smith", "description=A senior developer"},
+			expected: map[string]string{"full_name": "John Smith", "description": "A senior developer"},
+		},
+		{
+			name:     "value with equals sign",
+			varFlags: []string{"equation=x = y + 2"},
+			expected: map[string]string{"equation": "x = y + 2"},
+		},
+		{
+			name:     "empty strings are skipped",
+			varFlags: []string{"", "name=John", "  "},
+			expected: map[string]string{"name": "John"},
+		},
+		{
+			name:      "invalid format - no equals",
+			varFlags:  []string{"invalid"},
+			expectErr: true,
+		},
+		{
+			name:      "invalid format - empty key",
+			varFlags:  []string{"=value"},
+			expectErr: true,
+		},
+		{
+			name:      "duplicate keys",
+			varFlags:  []string{"name=John", "name=Jane"},
+			expectErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			flags := pflag.NewFlagSet("test", pflag.ContinueOnError)
+			flags.StringSlice("var", tt.varFlags, "test flag")
+
+			result, err := parseTemplateVariables(flags)
+
+			if tt.expectErr {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+				require.Equal(t, tt.expected, result)
+			}
+		})
+	}
+}

examples/advanced_template_prompt.yml

@@ -0,0 +1,27 @@
+# Advanced Template Variables Example
+name: Advanced Template Example
+description: Demonstrates advanced usage of template variables
+model: openai/gpt-4o-mini
+modelParameters:
+  temperature: 0.7
+  maxTokens: 300
+messages:
+  - role: system
+    content: |
+      You are {{assistant_persona}}, a {{expertise_level}} {{domain}} specialist.
+      Your communication style should be {{tone}} and {{formality_level}}.
+
+      Context: You are helping {{user_name}} who works as a {{user_role}} at {{company}}.
+
+  - role: user
+    content: |
+      Hello! I'm {{user_name}} from {{company}}.
+
+      Background: {{background_info}}
+
+      Question: {{input}}
+
+      Please provide your response considering my role as {{user_role}} and 
+      make it appropriate for a {{formality_level}} setting.
+
+      Additional context: {{additional_context}}

examples/template_variables_prompt.yml

@@ -0,0 +1,12 @@
+# Example demonstrating arbitrary template variables
+name: Template Variables Example
+description: Shows how to use custom template variables in prompt files
+model: openai/gpt-4o
+modelParameters:
+  temperature: 0.3
+  maxTokens: 200
+messages:
+  - role: system
+    content: You are {{persona}}, a helpful assistant specializing in {{domain}}.
+  - role: user
+    content: Hello {{name}}! I need help with {{topic}}. {{input}}