lifting tokenize_body, using lfs package

scripts/passes/word_count_eval.lua

@@ -29,13 +29,17 @@ local duffle        = dofile(_bootstrap_dir .. "../duffle_paths.lua")
 -- Constants
 -- ════════════════════════════════════════════════════════════════════════════
 
--- Windows separator chars — used to convert `dir /b /s` output (which uses `\`) into POSIX paths (which our scripts expect).
+-- Windows separator chars — used to convert `dir` output (which uses `\`) into POSIX paths (which our scripts expect).
 local PATH_SEP_BACKSLASH = "\\"
 local PATH_SEP_FORWARD   = "/"
 
--- Glob command for Windows directory walk. `dir /b /s` lists all matching files recursively with bare paths (no headers); 
--- `2>nul` discards the "file not found" stderr when nothing matches.
-local DIR_GLOB_CMD = 'dir /b /s "%s\\%s" 2>nul'
+-- Fallback glob command (subprocess). Used when `lfs` (LuaFileSystem) is not available.
+-- Scoped to `code\` to avoid walking `.git/`, `toolchain/`, `build/`, etc.
+local DIR_GLOB_CMD = 'dir /b /s "%s\\code\\%s" 2>nul'
+
+-- Try to load lfs (LuaFileSystem). If available, scan_dir uses native directory enumeration (~2ms)
+-- instead of spawning `dir /b /s` as a subprocess (~56ms). Built by update_deps.ps1 into toolchain/lfs/lfs.dll.
+local lfs = pcall(require, "lfs") and require("lfs") or nil
 
 -- ════════════════════════════════════════════════════════════════════════════
 -- Type declarations
@@ -120,36 +124,50 @@ end
 -- If a build removes/creates .macs.h files mid-process, the caller can invalidate by calling `M._invalidate_scan_cache()`.
 local SCAN_CACHE_KEY = "__word_count_eval_scan_cache__"
 
---- Recursively scan a directory for files matching a glob suffix.
---- No regex per the no_regex constraint — uses plain byte matching via `dir /b /s` on Windows.
+--- Scan `code/` for files matching `suffix` (e.g. `*.macs.h`).
+--- Uses `lfs` (LuaFileSystem) when available — native directory enumeration at ~2ms.
+--- Falls back to `dir /b /s` subprocess (~56ms) when `lfs` is not compiled.
 ---
---- @param dir string        -- directory to scan (absolute or relative)
+--- @param dir string        -- project root directory
 --- @param suffix string     -- file pattern, e.g. "*.macs.h"
 --- @return string[]
 function M.scan_dir(dir, suffix)
 	local key = dir .. "\0" .. suffix
 
-	-- Check the in-process cache first. (Mostly helps when a build triggers multiple `M.run` calls -- e.g. 
-	-- the audit_lua_nesting script's stress tests but the cost is ~free either way.)
 	local cache = package.loaded[SCAN_CACHE_KEY]
 	if    cache and cache[key] then return cache[key] end
 
 	local results = {}
-	local pipe = io.popen(DIR_GLOB_CMD:format(dir, suffix))
-	if not pipe then
-		-- Cache the empty result too (avoids re-scan if the dir is genuinely empty -- e.g. a clean build before components has run yet).
-		cache      = cache or {}
-		cache[key] = results
-		package.loaded[SCAN_CACHE_KEY] = cache
-		return results
-	end
-	for raw_line in pipe:lines() do
-		local path = raw_line:gsub(PATH_SEP_BACKSLASH, PATH_SEP_FORWARD)
-		results[#results + 1] = path
-	end
-	pipe:close()
 
-	-- Cache the result.
+	if lfs then
+		-- Native walk: list code/<module>/gen/ for matching files. Zero subprocess spawns.
+		local code_dir = dir .. "/code"
+		if lfs.attributes(code_dir, "mode") == "directory" then
+			for mod_name in lfs.dir(code_dir) do
+				if mod_name ~= "." and mod_name ~= ".." then
+					local gen_path = code_dir .. "/" .. mod_name .. "/gen"
+					if lfs.attributes(gen_path, "mode") == "directory" then
+						for fname in lfs.dir(gen_path) do
+							if fname:match("%.macs%.h$") then
+								results[#results + 1] = gen_path .. "/" .. fname
+							end
+						end
+					end
+				end
+			end
+		end
+	else
+		-- Fallback: single `dir /b /s` subprocess scoped to code\.
+		local pipe = io.popen(DIR_GLOB_CMD:format(dir, suffix))
+		if pipe then
+			for raw_line in pipe:lines() do
+				results[#results + 1] = raw_line:gsub(PATH_SEP_BACKSLASH, PATH_SEP_FORWARD)
+			end
+			pipe:close()
+		end
+	end
+
+	-- Cache the result (including empty results).
 	cache      = cache or {}
 	cache[key] = results
 	package.loaded[SCAN_CACHE_KEY] = cache