feat: add pi coding agent provider

pi/models.go

@@ -0,0 +1,47 @@
+package pi
+
+import "belaykit"
+
+// PricingForModel returns the token pricing for a given model ID.
+// Pi supports many providers; this covers common models. Returns
+// Claude Sonnet pricing as the default for unknown models.
+func PricingForModel(model string) belaykit.ModelPricing {
+	switch model {
+	// Anthropic
+	case "claude-opus-4-6":
+		return belaykit.ModelPricing{InputPerMTok: 5, OutputPerMTok: 25}
+	case "claude-sonnet-4-20250514", "claude-sonnet-4-5-20250929":
+		return belaykit.ModelPricing{InputPerMTok: 3, OutputPerMTok: 15}
+	case "claude-haiku-4-5-20251001":
+		return belaykit.ModelPricing{InputPerMTok: 1, OutputPerMTok: 5}
+	// OpenAI
+	case "gpt-4o":
+		return belaykit.ModelPricing{InputPerMTok: 2.5, OutputPerMTok: 10}
+	case "gpt-4o-mini":
+		return belaykit.ModelPricing{InputPerMTok: 0.15, OutputPerMTok: 0.6}
+	case "o3":
+		return belaykit.ModelPricing{InputPerMTok: 10, OutputPerMTok: 40}
+	// Google
+	case "gemini-2.5-pro":
+		return belaykit.ModelPricing{InputPerMTok: 1.25, OutputPerMTok: 10}
+	case "gemini-2.5-flash":
+		return belaykit.ModelPricing{InputPerMTok: 0.15, OutputPerMTok: 0.6}
+	default:
+		return belaykit.ModelPricing{InputPerMTok: 3, OutputPerMTok: 15}
+	}
+}
+
+// ContextWindowForModel returns the context window size in tokens for a given
+// model ID. Returns 200,000 as the default for unknown models.
+func ContextWindowForModel(model string) int {
+	switch model {
+	case "gpt-4o", "gpt-4o-mini":
+		return 128_000
+	case "o3":
+		return 200_000
+	case "gemini-2.5-pro", "gemini-2.5-flash":
+		return 1_000_000
+	default:
+		return 200_000
+	}
+}

pi/options.go

@@ -0,0 +1,83 @@
+package pi
+
+import "belaykit"
+
+// ClientOption configures a Client.
+type ClientOption func(*Client)
+
+// WithExecutable sets the path to the pi CLI binary.
+func WithExecutable(path string) ClientOption {
+	return func(c *Client) {
+		c.executable = path
+	}
+}
+
+// WithDefaultModel sets the default model for all runs. Supports pi's
+// provider/id format (e.g. "anthropic/claude-sonnet-4-20250514") and
+// optional thinking suffix (e.g. "sonnet:high").
+func WithDefaultModel(model string) ClientOption {
+	return func(c *Client) {
+		c.defaultModel = model
+	}
+}
+
+// WithDefaultProvider sets the default provider for all runs (e.g. "anthropic",
+// "openai", "google"). Can be omitted if the model string uses provider/id format.
+func WithDefaultProvider(provider string) ClientOption {
+	return func(c *Client) {
+		c.defaultProvider = provider
+	}
+}
+
+// WithDefaultThinking sets the default thinking level for all runs.
+// Valid levels: "off", "minimal", "low", "medium", "high", "xhigh".
+func WithDefaultThinking(level string) ClientOption {
+	return func(c *Client) {
+		c.defaultThinking = level
+	}
+}
+
+// WithDefaultEventHandler sets the default event handler for all runs.
+func WithDefaultEventHandler(h belaykit.EventHandler) ClientOption {
+	return func(c *Client) {
+		c.eventHandler = h
+	}
+}
+
+// WithObservability sets the observability provider for tracing and completion
+// recording. When set, Run automatically calls RecordCompletion on the provider
+// with data extracted from agent_end messages.
+func WithObservability(provider belaykit.ObservabilityProvider) ClientOption {
+	return func(c *Client) {
+		c.observability = provider
+	}
+}
+
+// WithTools sets the built-in tools to enable (e.g. "read", "bash", "edit", "write").
+// By default pi enables read, bash, edit, write.
+func WithTools(tools ...string) ClientOption {
+	return func(c *Client) {
+		c.tools = tools
+	}
+}
+
+// WithNoTools disables all built-in tools. Extension tools still work.
+func WithNoTools() ClientOption {
+	return func(c *Client) {
+		c.noTools = true
+	}
+}
+
+// WithExtension adds an extension to load (path, npm, or git source).
+func WithExtension(source string) ClientOption {
+	return func(c *Client) {
+		c.extensions = append(c.extensions, source)
+	}
+}
+
+// WithWorkDir sets the working directory for the pi process.
+func WithWorkDir(dir string) ClientOption {
+	return func(c *Client) {
+		c.workDir = dir
+	}
+}