feat(health): add picker backend, persist, and tree-sitter diagnostics

Extend :checkhealth to verify that the configured picker backend plugin
is installed, report persist status and git repo detection, and check
tree-sitter parser availability when ui.title.context is enabled.

Author: mhiro2

lua/peekstack/health.lua

@@ -1,5 +1,12 @@
 local M = {}
 
+---@type table<string, string>
+local PICKER_MODULES = {
+  telescope = "telescope",
+  ["fzf-lua"] = "fzf-lua",
+  snacks = "snacks",
+}
+
 function M.check()
   vim.health.start("peekstack")
 
@@ -14,6 +21,54 @@ function M.check()
   else
     vim.health.warn("rg not found (grep.search will be unavailable)")
   end
+
+  local ok, cfg_mod = pcall(require, "peekstack.config")
+  if not ok then
+    return
+  end
+  local cfg = cfg_mod.get()
+
+  -- Picker backend
+  local backend = cfg.picker and cfg.picker.backend
+  if backend and backend ~= "builtin" then
+    local plugin_name = PICKER_MODULES[backend]
+    if plugin_name then
+      local has = pcall(require, plugin_name)
+      if has then
+        vim.health.ok("picker backend '" .. backend .. "' available")
+      else
+        vim.health.warn("picker backend '" .. backend .. "' is configured but the plugin is not installed")
+      end
+    else
+      vim.health.warn("unknown picker backend '" .. backend .. "'")
+    end
+  end
+
+  -- Persist
+  local persist = cfg.persist
+  if persist and persist.enabled then
+    local fs = require("peekstack.util.fs")
+    local repo = fs.repo_root()
+    if repo then
+      vim.health.ok("persist enabled (repo: " .. repo .. ")")
+    else
+      vim.health.warn("persist enabled but not inside a git repository; sessions will use cwd-based storage")
+    end
+    if persist.auto and persist.auto.enabled then
+      vim.health.ok("auto persist enabled (session: " .. (persist.auto.session_name or "auto") .. ")")
+    end
+  end
+
+  -- Tree-sitter context
+  local title = cfg.ui and cfg.ui.title
+  if title and title.context and title.context.enabled then
+    local ts_ok = pcall(vim.treesitter.get_parser, 0)
+    if ts_ok then
+      vim.health.ok("tree-sitter context enabled (parser available for current buffer)")
+    else
+      vim.health.info("tree-sitter context enabled but no parser for the current buffer filetype")
+    end
+  end
 end
 
 return M

tests/health_spec.lua

@@ -0,0 +1,126 @@
+describe("peekstack.health", function()
+  local health = require("peekstack.health")
+  local config = require("peekstack.config")
+
+  local original_health_start
+  local original_health_ok
+  local original_health_warn
+  local original_health_error
+  local original_health_info
+  local original_executable
+  local original_has
+
+  ---@type string[]
+  local messages
+
+  before_each(function()
+    messages = {}
+    original_health_start = vim.health.start
+    original_health_ok = vim.health.ok
+    original_health_warn = vim.health.warn
+    original_health_error = vim.health.error
+    original_health_info = vim.health.info
+    original_executable = vim.fn.executable
+    original_has = vim.fn.has
+
+    vim.health.start = function() end
+    vim.health.ok = function(msg)
+      table.insert(messages, "ok:" .. msg)
+    end
+    vim.health.warn = function(msg)
+      table.insert(messages, "warn:" .. msg)
+    end
+    vim.health.error = function(msg)
+      table.insert(messages, "error:" .. msg)
+    end
+    vim.health.info = function(msg)
+      table.insert(messages, "info:" .. msg)
+    end
+  end)
+
+  after_each(function()
+    vim.health.start = original_health_start
+    vim.health.ok = original_health_ok
+    vim.health.warn = original_health_warn
+    vim.health.error = original_health_error
+    vim.health.info = original_health_info
+    vim.fn.executable = original_executable
+    vim.fn.has = original_has
+    config.setup({})
+  end)
+
+  it("reports ok for nvim version and rg when available", function()
+    vim.fn.has = function()
+      return 1
+    end
+    vim.fn.executable = function()
+      return 1
+    end
+    config.setup({})
+
+    health.check()
+
+    assert.is_true(vim.list_contains(messages, "ok:nvim >= 0.10"))
+    assert.is_true(vim.list_contains(messages, "ok:rg available"))
+  end)
+
+  it("warns when rg is not available", function()
+    vim.fn.has = function()
+      return 1
+    end
+    vim.fn.executable = function()
+      return 0
+    end
+    config.setup({})
+
+    health.check()
+
+    local found = false
+    for _, msg in ipairs(messages) do
+      if msg:find("warn:rg not found") then
+        found = true
+      end
+    end
+    assert.is_true(found)
+  end)
+
+  it("warns when configured picker backend is not installed", function()
+    vim.fn.has = function()
+      return 1
+    end
+    vim.fn.executable = function()
+      return 1
+    end
+    config.setup({ picker = { backend = "telescope" } })
+
+    health.check()
+
+    local found = false
+    for _, msg in ipairs(messages) do
+      if msg:find("warn:") and msg:find("telescope") and msg:find("not installed") then
+        found = true
+      end
+    end
+    assert.is_true(found)
+  end)
+
+  it("reports persist status when enabled inside a git repo", function()
+    vim.fn.has = function()
+      return 1
+    end
+    vim.fn.executable = function()
+      return 1
+    end
+    config.setup({ persist = { enabled = true } })
+
+    health.check()
+
+    local found_persist = false
+    for _, msg in ipairs(messages) do
+      if msg:find("persist") then
+        found_persist = true
+      end
+    end
+    assert.is_true(found_persist)
+  end)
+end)