feat(lsp): experimental in-process LSP server with hover support

.changeset/experimental-lsp-hover.md

@@ -0,0 +1,5 @@
+---
+"@flemma-dev/flemma.nvim": minor
+---
+
+Added experimental in-process LSP server for chat buffers with hover and goto-definition support. Enable with `experimental = { lsp = true }` in setup. Every buffer position returns a hover result: segments (expressions, thinking blocks, tool use/result, text) show structured dumps, role markers show message summaries with segment breakdowns, and frontmatter shows language and code. Goto-definition (`gd`, `<C-]>`, etc.) on `@./file` references and `{{ include() }}` expressions jumps to the referenced file, reusing the navigation module's path resolution.

Makefile

@@ -66,7 +66,7 @@ develop:
 				[\"\$$gpt\"] = \"openai gpt-5.2\",										\
 			},																			\
 			diagnostics = { enabled = true },											\
-			logging = { enabled = true },												\
+			logging = { enabled = true, level = "TRACE" },								\
 			editing = { auto_write = true },											\
 			tools = { modules = { \"extras.flemma.tools.calculator\" } },				\
 		})																				\

lua/flemma/ast/query.lua

@@ -85,54 +85,56 @@ function M.find_segment_at_position(doc, lnum, col)
   for _, msg in ipairs(doc.messages) do
     local msg_start = msg.position.start_line
     local msg_end = msg.position.end_line or msg_start
-    if lnum < msg_start or lnum > msg_end then
-      goto continue_msg
-    end
 
-    ---@type flemma.ast.Segment|nil
-    local fallback_seg = nil
+    if lnum >= msg_start and lnum <= msg_end then
+      ---@type flemma.ast.Segment|nil
+      local fallback_seg = nil
+      for _, seg in ipairs(msg.segments) do
+        if not seg.position then
+          goto continue_seg
+        end
 
-    for _, seg in ipairs(msg.segments) do
-      if not seg.position then
-        goto continue_seg
-      end
+        local seg_start = seg.position.start_line
+        local seg_end = seg.position.end_line or seg_start
 
-      local seg_start = seg.position.start_line
-      local seg_end = seg.position.end_line or seg_start
+        if lnum < seg_start or lnum > seg_end then
+          goto continue_seg
+        end
 
-      if lnum < seg_start or lnum > seg_end then
-        goto continue_seg
-      end
+        -- Line matches. Refine with column if available.
+        if lnum == seg_start and seg.position.start_col and seg.position.end_col then
+          if col >= seg.position.start_col and col <= seg.position.end_col then
+            return seg, msg
+          end
+          goto continue_seg
+        end
 
-      -- Line matches. Refine with column if available.
-      if lnum == seg_start and seg.position.start_col and seg.position.end_col then
-        if col >= seg.position.start_col and col <= seg.position.end_col then
+        -- Multi-line hit beyond first line — definite match
+        if lnum > seg_start then
           return seg, msg
         end
-        goto continue_seg
-      end
 
-      -- Multi-line hit beyond first line — definite match
-      if lnum > seg_start then
-        return seg, msg
-      end
+        -- Single-line segment without column info — save as fallback
+        -- so column-aware segments on the same line get a chance to match first
+        if not seg.position.start_col then
+          fallback_seg = seg
+        end
 
-      -- Single-line segment without column info — save as fallback
-      if not fallback_seg then
-        fallback_seg = seg
+        ::continue_seg::
       end
 
-      ::continue_seg::
-    end
+      -- Return fallback if no column-specific match found
+      if fallback_seg then
+        return fallback_seg, msg
+      end
 
-    -- Return fallback if no column-specific match found
-    if fallback_seg then
-      return fallback_seg, msg
+      -- Cursor is within the message range but no segment matched
+      -- (e.g., on the @Role: marker line). Return the message itself.
+      return nil, msg
     end
-
-    ::continue_msg::
   end
   return nil, nil
 end
 
+
 return M

lua/flemma/config.lua

@@ -146,6 +146,9 @@
 ---@field insert flemma.config.InsertKeymaps
 ---@field enabled boolean
 
+---@class flemma.config.Experimental
+---@field lsp boolean Enable in-process LSP for .chat buffers
+
 ---User-facing setup options — every field is optional (merged with defaults).
 ---@class flemma.Config.Opts
 ---@field defaults? { dark: { bg: string, fg: string }, light: { bg: string, fg: string } }
@@ -168,6 +171,7 @@
 ---@field keymaps? flemma.config.Keymaps
 ---@field sandbox? flemma.config.SandboxConfig
 ---@field diagnostics? flemma.config.Diagnostics
+---@field experimental? flemma.config.Experimental
 
 ---Full resolved config (all fields present after merging with defaults).
 ---@class flemma.Config : flemma.Config.Opts
@@ -190,6 +194,7 @@
 ---@field keymaps flemma.config.Keymaps
 ---@field sandbox flemma.config.SandboxConfig
 ---@field diagnostics flemma.config.Diagnostics
+---@field experimental flemma.config.Experimental
 
 ---@type flemma.Config
 return {
@@ -347,4 +352,7 @@ return {
       },
     },
   },
+  experimental = {
+    lsp = vim.lsp ~= nil,
+  },
 }

lua/flemma/init.lua

@@ -22,6 +22,7 @@ local tools_presets = require("flemma.tools.presets")
 local tools_approval = require("flemma.tools.approval")
 local cursor = require("flemma.cursor")
 local sandbox = require("flemma.sandbox")
+local lsp = require("flemma.lsp")
 
 -- Module configuration (will hold merged user opts and defaults)
 local config = {}
@@ -145,6 +146,11 @@ M.setup = function(user_opts)
   -- Register built-in sandbox backends and validate availability
   sandbox.setup()
 
+  -- Set up experimental LSP if enabled
+  if config.experimental and config.experimental.lsp then
+    lsp.setup()
+  end
+
   -- Defer sandbox backend check until the user enters a .chat buffer.
   -- By that time, other plugins may have registered additional backends.
   if config.sandbox and config.sandbox.enabled then