Prevent duplicate instruction appending in generate_prompts

lua/avante/llm.lua

@@ -262,11 +262,14 @@ function M.generate_prompts(opts)
   local project_root = Utils.root.get()
   local instruction_file_path = PPath:new(project_root, project_instruction_file)
 
-  if instruction_file_path:exists() then
+  if instruction_file_path:exists() and not opts._instructions_loaded then
     local lines = Utils.read_file_from_buf_or_disk(instruction_file_path:absolute())
     local instruction_content = lines and table.concat(lines, "\n") or ""
 
-    if instruction_content then opts.instructions = (opts.instructions or "") .. "\n" .. instruction_content end
+    if instruction_content then 
+      opts.instructions = (opts.instructions or "") .. "\n" .. instruction_content 
+    end
+    opts._instructions_loaded = true
   end
 
   local mode = opts.mode or Config.mode
@@ -438,8 +441,9 @@ function M.generate_prompts(opts)
     :filter(function(msg) return type(msg.content) ~= "string" or msg.content ~= "" end)
     :totable()
 
-  if opts.instructions ~= nil and opts.instructions ~= "" then
+  if opts.instructions ~= nil and opts.instructions ~= "" and not opts._instructions_added_to_messages then
     messages = vim.list_extend(messages, { { role = "user", content = opts.instructions } })
+    opts._instructions_added_to_messages = true
   end
 
   opts.session_ctx = opts.session_ctx or {}

tests/llm_spec.lua

@@ -151,4 +151,47 @@ describe("generate_prompts", function()
     assert.are.same(#result.tools, 1)
     assert.are.same(result.tools[1].name, "test_tool")
   end)
+
+  it("should not duplicate instruction file content when called multiple times with same opts", function()
+    local opts = {}
+    llm.generate_prompts(opts)
+    local first_instructions = opts.instructions
+
+    -- Call again with the same opts object
+    llm.generate_prompts(opts)
+    local second_instructions = opts.instructions
+
+    -- Instructions should be the same, not duplicated
+    assert.are.same(first_instructions, second_instructions)
+    -- Verify that mock content is present (more flexible than hardcoded exact match)
+    assert.truthy(string.find(opts.instructions, "Mock Instructions"))
+  end)
+
+  it("should not duplicate instructions in messages when called multiple times with same opts", function()
+    local opts = {
+      instructions = "Test instructions"
+    }
+
+    -- First call
+    local result1 = llm.generate_prompts(opts)
+    local instruction_message_count1 = 0
+    for _, msg in ipairs(result1.session_ctx.messages) do
+      if msg.role == "user" and msg.content == "Test instructions" then
+        instruction_message_count1 = instruction_message_count1 + 1
+      end
+    end
+
+    -- Second call with same opts
+    local result2 = llm.generate_prompts(opts)
+    local instruction_message_count2 = 0
+    for _, msg in ipairs(result2.session_ctx.messages) do
+      if msg.role == "user" and msg.content == "Test instructions" then
+        instruction_message_count2 = instruction_message_count2 + 1
+      end
+    end
+
+    -- Should have instructions message only once in both calls
+    assert.are.same(1, instruction_message_count1)
+    assert.are.same(1, instruction_message_count2)
+  end)
 end)