AI chat panel with Edit/Chat modes + verify dropdown

- AI chat panel at bottom of editor (all 3 modes)
- Edit mode: AI modifies document directly (no explanations)
- Chat mode: AI answers questions about the document
- Verify dropdown: Spec Review, Grammar & Spelling, Summary
- Enter sends, Shift+Enter for newline
- /api/ai/chat endpoint with edit/chat system prompts
- Grammar and spec verify actions added to /api/ai/generate

internal/api/ai.go

@@ -98,12 +98,21 @@ func (s *Server) handleAIGenerate(w http.ResponseWriter, r *http.Request) {
 
 	systemPrompt := "You are a helpful assistant. Respond in markdown."
 	switch req.Action {
-	case "summarize":
+	case "summarize", "summary":
 		systemPrompt = "Summarize the following text concisely in markdown."
 	case "prompt":
 		systemPrompt = "Generate a detailed AI prompt based on the following specification. The prompt should instruct an AI coding agent to implement the project."
 	case "expand":
 		systemPrompt = "Expand on the following text with more detail, examples, and explanations. Respond in markdown."
+	case "grammar":
+		systemPrompt = "Review the following text for grammar and spelling errors. List each error with the correction. Be concise. Format as a markdown list."
+	case "spec":
+		systemPrompt = `You are a technical reviewer. Review the following specification document for:
+1. Completeness - are there missing details needed to implement this?
+2. Ambiguities - are there unclear requirements?
+3. Feasibility - is this technically achievable?
+4. Suggestions - any improvements?
+Respond with a structured review. End with a clear verdict: READY TO BUILD or NEEDS REVISION.`
 	}
 
 	response, err := callLLM(aiEndpoint, aiKey, aiModel, systemPrompt, inputText)
@@ -118,7 +127,58 @@ func (s *Server) handleAIGenerate(w http.ResponseWriter, r *http.Request) {
 		files.WriteFile(s.dataDir, userID, filename, response)
 	}
 
-	writeJSON(w, 200, map[string]string{"output": response})
+	writeJSON(w, 200, map[string]string{"result": response})
+}
+
+func (s *Server) handleAIChat(w http.ResponseWriter, r *http.Request) {
+	var req struct {
+		Path    string `json:"path"`
+		Content string `json:"content"`
+		Message string `json:"message"`
+		Mode    string `json:"mode"` // "edit" or "chat"
+	}
+	if err := decodeBody(r, &req); err != nil || req.Message == "" {
+		writeJSON(w, 400, map[string]string{"error": "message required"})
+		return
+	}
+
+	aiEndpoint := os.Getenv("MH_AI_ENDPOINT")
+	aiKey := os.Getenv("MH_AI_API_KEY")
+	aiModel := os.Getenv("MH_AI_MODEL")
+	if aiEndpoint == "" {
+		writeJSON(w, 500, map[string]string{"error": "AI endpoint not configured"})
+		return
+	}
+	if aiModel == "" {
+		aiModel = "gpt-4"
+	}
+
+	var systemPrompt string
+	var userMsg string
+
+	if req.Mode == "edit" {
+		systemPrompt = `You are a document editor. The user will give you a markdown document and an instruction.
+Apply the instruction to the document and return ONLY the complete updated document.
+Do not add explanations, comments, or markdown code fences around the output.
+Preserve the document's existing style and formatting.`
+		userMsg = "Document:\n\n" + req.Content + "\n\nInstruction: " + req.Message
+	} else {
+		systemPrompt = `You are a helpful writing assistant. The user has a markdown document open and is asking a question about it.
+Answer concisely in markdown. Reference the document content when relevant.`
+		userMsg = "Document:\n\n" + req.Content + "\n\nQuestion: " + req.Message
+	}
+
+	response, err := callLLM(aiEndpoint, aiKey, aiModel, systemPrompt, userMsg)
+	if err != nil {
+		writeJSON(w, 500, map[string]string{"error": "AI call failed: " + err.Error()})
+		return
+	}
+
+	if req.Mode == "edit" {
+		writeJSON(w, 200, map[string]string{"content": response})
+	} else {
+		writeJSON(w, 200, map[string]string{"result": response})
+	}
 }
 
 func callLLM(endpoint, apiKey, model, systemPrompt, userContent string) (string, error) {