Add OpenRouter reasoning support

internal/llm/client_completions.go

@@ -444,6 +444,13 @@ func (c *Client) completionsStream(ctx context.Context, messages []Message, mode
 					ReasoningDelta: delta.ReasoningContent,
 				}
 			}
+			if delta.Reasoning != "" {
+				acc.reasoning.WriteString(delta.Reasoning)
+				events <- StreamEvent{
+					Type:           streamEventReasoningDelta,
+					ReasoningDelta: delta.Reasoning,
+				}
+			}
 			// Accumulate tool call deltas by index.
 			for _, tc := range delta.ToolCalls {
 				idx := 0

internal/llm/llm.go

@@ -138,6 +138,7 @@ type Delta struct {
 	Content          string     `json:"content,omitempty"`
 	Refusal          string     `json:"refusal,omitempty"`
 	ReasoningContent string     `json:"reasoning_content,omitempty"`
+	Reasoning        string     `json:"reasoning,omitempty"`
 	ToolCalls        []ToolCall `json:"tool_calls,omitempty"`
 }
 
@@ -199,6 +200,7 @@ type Message struct {
 	ContentParts     []ContentPart `json:"content,omitempty"`
 	Refusal          string        `json:"refusal,omitempty"`
 	ReasoningContent string        `json:"reasoning_content,omitempty"`
+	Reasoning        string        `json:"reasoning,omitempty"`
 	Name             string        `json:"name,omitempty"`
 	ToolCalls        []ToolCall    `json:"tool_calls,omitempty"`
 	ToolCallID       string        `json:"tool_call_id,omitempty"`
@@ -244,6 +246,10 @@ func (m *Message) UnmarshalJSON(data []byte) error {
 			m.ContentParts = append(m.ContentParts, part)
 		}
 	}
+	// Normalize: if ReasoningContent is empty but Reasoning is set, use Reasoning
+	if m.ReasoningContent == "" && m.Reasoning != "" {
+		m.ReasoningContent = m.Reasoning
+	}
 	return nil
 }
 
@@ -254,6 +260,7 @@ type Model struct {
 	Object        string     `json:"object"`
 	OwnedBy       string     `json:"owned_by"`
 	Meta          *ModelMeta `json:"meta,omitempty"`
+	ContextLength int        `json:"context_length,omitempty"`
 }
 
 // ModelMeta contains optional model metadata from the provider.

internal/service/service.go

@@ -833,8 +833,12 @@ func (svc *Service) models(w http.ResponseWriter, r *http.Request) {
 			for _, m := range models {
 				baseID, _, _ := strings.Cut(m.ID, ":")
 				available[baseID] = struct{}{}
-				if m.Meta != nil && m.Meta.NCtx > 0 {
+				cs := m.ContextLength
-					contextSizes[baseID] = m.Meta.NCtx
+				if cs == 0 && m.Meta != nil {
+					cs = m.Meta.NCtx
+				}
+				if cs > 0 {
+					contextSizes[baseID] = cs
 				}
 			}