mcp-line-mover

MCP stdio server that lets coding agents move contiguous line ranges between files without copying the text through their own context window. The agent supplies only (source_path, start_line, end_line, dest_path, dest_line, placement); the server reads, hashes, snapshots, and rewrites files internally.

See SPEC.md for the authoritative spec and CLAUDE.md for engineering conventions.

Install

In your MCP client config (e.g. ~/.claude.json for Claude Code):

{
  "mcpServers": {
    "line-mover": {
      "command": "npx",
      "args": ["-y", "mcp-line-mover"]
    }
  }
}

That's it. No env block needed for typical use — the server detects each repo automatically by walking up to the nearest .git directory. Works the same in every repo on your machine.

For locked-down or CI use, set LINE_MOVER_ROOT to pin a single workspace.

Tools

• preview_move_lines — validate and record a proposed move; returns operation_id (non-mutating).
• execute_operation — apply a previewed move by id; refuses if files changed since preview.
• move_lines — one-shot preview+execute.
• undo_operation — restore from snapshot; refuses if files changed after execution.

How workspace roots work

By default the server runs in inferred mode:

• Each tool call walks up from the path arguments to find the nearest workspace marker (default .git, configurable via LINE_MOVER_ROOT_MARKERS).
• Source and dest must resolve to the same workspace; cross-repo moves are rejected.
• Operations and snapshots live under each repo's own .mcp-line-mover/ directory — add it to .gitignore.
• A small index at ~/.mcp-line-mover/roots.log tracks which repos have outstanding operations so execute_operation and undo_operation work even after Claude Code restarts.

If LINE_MOVER_ROOT is set, inferred mode is disabled and the server operates as a single-root server (matching the original spec behavior).

Configuration

LINE_MOVER_ROOT                 # default: unset (inferred mode); set to pin
LINE_MOVER_MAX_LINES            # default: 2000
LINE_MOVER_MAX_FILE_SIZE_MB     # default: 5
LINE_MOVER_ALLOW_CREATE         # default: false
LINE_MOVER_CREATE_PARENT_DIRS   # default: false
LINE_MOVER_DENY_GLOBS           # additive to defaults
LINE_MOVER_SNAPSHOT_DIR         # default: .mcp-line-mover
LINE_MOVER_OPERATION_TTL_DAYS   # default: 14
LINE_MOVER_ROOT_MARKERS         # default: .git (comma-separated; first match wins)
LINE_MOVER_MAX_ROOT_WALK        # default: 25 (hard cap 100)
LINE_MOVER_REGISTRY_DIR         # default: <home>/.mcp-line-mover
LINE_MOVER_AUDIT_SILENT         # set to "1" to silence stderr audit lines

Develop

npm install
npm test         # unit + integration (266 tests)
npm run test:e2e # spawns the built binary via stdio
npm run build
npm run typecheck