search_code returns 0 results for .mjs files #197

Description

search_code returns zero results for any pattern searched in .mjs (ES module) files, even though the files are indexed and search_graph finds nodes within them.

Environment

• Version: 0.5.7 (upgraded from 0.4.10, same issue on both)
• OS: Windows 11 Pro 10.0.26300
• Project: Mixed codebase — Python (.py), JavaScript (.mjs, .jsx, .js), Markdown

Steps to Reproduce

1. Index a repository containing .mjs files (Express server routes in our case)
2. Run search_code with a pattern that exists in those files

{
  "pattern": "router.get",
  "project": "my-project",
  "path_filter": "dashboard/server",
  "mode": "compact",
  "limit": 10
}

Result: {"results":[], "total_grep_matches": 0, "total_results": 0}

3. Verify with native grep — the pattern exists in 9 files (25 occurrences):

server/routes/archive.mjs:1
server/routes/hurtiglogg.mjs:3
server/routes/projects.mjs:4
server/routes/tidslinje.mjs:2
server/routes/economics.mjs:6
server/routes/epost.mjs:1
server/routes/planner.mjs:2
server/routes/system.mjs:2
server/routes/tasks.mjs:4

Additional patterns tested (all return 0 for .mjs)

• asyncHandler — used in 40+ route handlers across .mjs files → 0 results
• router.post → 0 results
• process.env → 0 results (when filtered to *.mjs)

What works

• search_graph with label: Route returns nodes from .mjs files — so indexing parses them correctly
• search_code works for .py and .js files
• Native grep/ripgrep finds all patterns correctly

Likely cause

The internal grep in search_code may not include .mjs in its list of recognized JavaScript file extensions, so it skips these files entirely during the text search phase. The graph indexer (tree-sitter) handles them fine.

Workaround

Using the file_pattern parameter with *.mjs also returns 0, so there is no workaround within the tool.