feat: config, OpenAI-compatible streaming provider and safe tools

internal/llm/llm.go

@@ -0,0 +1,53 @@
+// Package llm defines the provider abstraction and message types.
+package llm
+
+import "context"
+
+type Role string
+
+const (
+	RoleSystem    Role = "system"
+	RoleUser      Role = "user"
+	RoleAssistant Role = "assistant"
+	RoleTool      Role = "tool"
+)
+
+type ToolCall struct {
+	ID        string `json:"id"`
+	Name      string `json:"name"`
+	Arguments string `json:"arguments"` // raw JSON
+}
+
+type Message struct {
+	Role       Role       `json:"role"`
+	Content    string     `json:"content"`
+	ToolCalls  []ToolCall `json:"tool_calls,omitempty"`
+	ToolCallID string     `json:"tool_call_id,omitempty"`
+	Name       string     `json:"name,omitempty"`
+}
+
+// ToolSpec describes a callable tool using JSON Schema parameters.
+type ToolSpec struct {
+	Name        string         `json:"name"`
+	Description string         `json:"description"`
+	Parameters  map[string]any `json:"parameters"`
+}
+
+type Request struct {
+	Messages []Message
+	Tools    []ToolSpec
+}
+
+// Response is the final assembled assistant turn.
+type Response struct {
+	Content      string
+	ToolCalls    []ToolCall
+	FinishReason string
+}
+
+// DeltaFunc receives streamed text tokens. May be nil.
+type DeltaFunc func(text string)
+
+type Provider interface {
+	Chat(ctx context.Context, req Request, onDelta DeltaFunc) (Response, error)
+}