Completions api (#8) (#29)

server/providers/provider.go

@@ -0,0 +1,85 @@
+package providers
+
+import (
+	"context"
+)
+
+// ── Provider Interface ──────────────────────
+
+// Provider is the contract for LLM API adapters.
+type Provider interface {
+	// ID returns the provider identifier (e.g. "openai", "anthropic").
+	ID() string
+
+	// ChatCompletion sends a non-streaming request and returns the full response.
+	ChatCompletion(ctx context.Context, cfg ProviderConfig, req CompletionRequest) (*CompletionResponse, error)
+
+	// StreamCompletion sends a streaming request and returns a channel of events.
+	// The channel is closed when the stream ends. Errors are sent as StreamEvents.
+	StreamCompletion(ctx context.Context, cfg ProviderConfig, req CompletionRequest) (<-chan StreamEvent, error)
+
+	// ListModels returns available models from this provider.
+	ListModels(ctx context.Context, cfg ProviderConfig) ([]Model, error)
+}
+
+// ── Configuration ───────────────────────────
+
+// ProviderConfig holds credentials and endpoint for a configured provider.
+// Populated from the api_configs table at call time.
+type ProviderConfig struct {
+	Endpoint string
+	APIKey   string
+	Extra    map[string]interface{} // Provider-specific settings from config JSONB
+}
+
+// ── Request / Response Types ────────────────
+
+// Message represents a chat message in the conversation.
+type Message struct {
+	Role    string `json:"role"`    // user, assistant, system
+	Content string `json:"content"`
+}
+
+// CompletionRequest is the normalized request sent to any provider.
+type CompletionRequest struct {
+	Model       string    `json:"model"`
+	Messages    []Message `json:"messages"`
+	MaxTokens   int       `json:"max_tokens,omitempty"`
+	Temperature *float64  `json:"temperature,omitempty"`
+	TopP        *float64  `json:"top_p,omitempty"`
+	Stream      bool      `json:"stream,omitempty"`
+}
+
+// CompletionResponse is the normalized non-streaming response.
+type CompletionResponse struct {
+	Content      string `json:"content"`
+	Model        string `json:"model"`
+	FinishReason string `json:"finish_reason"`
+	InputTokens  int    `json:"input_tokens"`
+	OutputTokens int    `json:"output_tokens"`
+}
+
+// StreamEvent is a single chunk from a streaming response.
+type StreamEvent struct {
+	// Delta is the incremental text content (empty for non-content events).
+	Delta string `json:"delta,omitempty"`
+
+	// Done is true when the stream is complete.
+	Done bool `json:"done,omitempty"`
+
+	// FinishReason is set on the final event.
+	FinishReason string `json:"finish_reason,omitempty"`
+
+	// Model echoes back the model used.
+	Model string `json:"model,omitempty"`
+
+	// Error is set if the stream encountered an error.
+	Error error `json:"-"`
+}
+
+// Model represents an available model from a provider.
+type Model struct {
+	ID      string `json:"id"`
+	Name    string `json:"name,omitempty"`
+	OwnedBy string `json:"owned_by,omitempty"`
+}