Mellos Mapping

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A live, terminal-native map of bottom-up development for Claude Code, ChatGPT desktop Codex mode and Codex CLI.

While Claude builds your system, a split pane beside the conversation shows the system's layered dependency map: primitive layers at the bottom, dependency edges that may only point downward, ghost nodes for what is designed, a spinner on what is being built right now, and solid green for what is built and verified.

A real session: Claude Code on the left, the map pane on the right. L0 is verified, L1 just lit up, everything above is still a ghost.

Why

Most progress reporting is a task list — a top-down worldview. A Mellos map grows the other way: an upper node can only stand on nodes below it, and the picture makes the discipline visible:

• The ghost design appears before any code. Claude declares the whole intended structure as dashed ghost nodes first; you can veto a bad design while it is still only a picture.

• The spinner is where Claude's attention is. One glance answers "what is it doing right now, and on top of what?"

• Done means verified. A node turns solid green only with evidence (a passing test run). If later work cracks a foundation, the node turns red — a cracked foundation under a spinning upper floor is the most honest status report there is.

• The map is a ledger, not a judge. The tools refuse only structural corruption (an edge pointing upward, a duplicate rank). Workflow is Claude's discipline, defined in the bundled skill; violations are made visible, never silently blocked.

Related MCP server: memory-lab-2sep

Install

Clone the branch for your host, then run one command. No build is required.

Requires Node.js 18.17+ on the 18.x line, or 20.3+, and the corresponding host CLI on PATH. Supported platforms are Windows 10+, macOS 13.0+ and Linux with glibc 2.28+, each on x64 or arm64. The OS must also meet the selected Node.js version's requirements. Native lock bindings ship with the release; no local compilation is needed. The installer checks release integrity and all eight MCP tools, retains the runtime outside the clone, and configures the host. Start a new conversation after installation. See release and branch instructions.

Claude Code's marketplace installation is also available:

Two lines inside any Claude Code conversation:

/plugin marketplace add GuangminJu/mellos-mapping
/plugin install mellos-mapping@mellos-mapping

Or one line in a terminal:

claude plugin marketplace add GuangminJu/mellos-mapping && claude plugin install mellos-mapping@mellos-mapping

Requires the same Node.js and platform versions on PATH (install Node separately when using native Claude Code). No build step: dist/ is committed, so a clone runs as-is — dist/server.mjs (the MCP server), dist/watch.mjs (the pane), dist/mmap.mjs (the mmap toggle), dist/hook-session-start.mjs (the SessionStart hook that hooks/hooks.json registers) and dist/store-paths.mjs (the store's path vocabulary, which the plain-node pane launcher imports instead of restating filenames).

omp (Oh My Pi) reads the same plugin layout the Claude Code edition ships — the same marketplace catalog, .mcp.json, skill and slash command — so one release serves both hosts:

omp plugin marketplace add GuangminJu/mellos-mapping
omp plugin install mellos-mapping@mellos-mapping

That install follows main, where a release is a version bump. To freeze a version instead, add a checkout of one — the Claude Code edition ZIP from the GitHub Release, or a clone at the release tag:

omp plugin marketplace add "<checkout or extracted release directory>"
omp plugin install mellos-mapping@mellos-mapping

omp never reads hooks/hooks.json, so the session paragraph arrives through the plugin's omp host adapter (dist/omp-extension.mjs, declared in package.json#omp.extensions): the same store, the same policy text, and the same mmap shim install as the Claude hook. The pane is the same terminal split beside the session. Install it as a plugin: neither omp plugin link nor the npm package is a plugin, and both would leave the tools behind. See omp installation and limitations.

pi reads none of that layout: it loads an extension and has no MCP of its own, by design. So the plugin speaks MCP to itself — the extension declared in package.json#pi.extensions (dist/pi-extension.mjs) starts the same dist/server.mjs in the session's directory, which makes the eight mmap_* tools the same eight, under the same names, and builds the session paragraph from the same store and the same policy text the Claude hook prints:

pi install npm:mellos-mapping

Add -l to install it for the current project instead of every one, then start a new session: pi discovers packages at session start. The package's skills/ and commands/ travel with it — the same map discipline, and /mmap for the same slash command. See pi installation and behaviour.

The first session after installing asks you one question — how eager mapping should be — and records the answer for every project you will ever open. From then on the hook carries it into each new session by itself; there is no per-project setup step. See Setup: choose when maps open.

The mmap terminal command (the pane's open/close toggle) installs itself on Windows: the same hook notices on session start when the shim is missing or points at an older install, writes mmap.cmd (cmd, PowerShell) and mmap (git-bash) into %LOCALAPPDATA%\mellos-mapping\bin, appends that one directory to your user PATH, and tells you so through the assistant. The PATH change reaches only new processes — and a new tab of a running Windows Terminal inherits the old environment, so close the terminal app entirely and reopen it before the first mmap. The PATH edit keeps the installer's guarantees: nothing happens when the entry is already there, and a PATH that setx would damage (flattened %VARIABLE% references, truncation past its limit) is refused outright.

A refused PATH is not a dead end: the same two shims are then written into %LOCALAPPDATA%\Microsoft\WindowsApps (or ~/.local/bin) — a directory your PATH already names — so mmap is runnable in a new terminal with no PATH change at all. Machines with a long PATH are exactly where that happens, and where it matters most. The command takes the page to open as an argument (mmap omp-host-support), and closes the pane when it is already open.

The step behind it is still a command of its own, for the cases the hook does not cover — --uninstall, or re-adding a PATH entry you removed while the shims stayed put:

node "<plugin dir>/scripts/install-mmap-command.mjs" [--uninstall]

(--json prints the install outcome as one JSON line instead of prose — the mode the hook itself calls it in.) npm i -g mellos-mapping provides the same mmap via bin, no shims involved.

Update

claude plugin marketplace update mellos-mapping && claude plugin update mellos-mapping@mellos-mapping

Two steps because plugin update compares against the locally cached marketplace clone — the first command is what actually pulls this repo. Restart Claude Code to apply. Releases are version bumps on main. (In-app, /plugin opens the same management UI.)

omp updates with its own two steps:

omp plugin marketplace update mellos-mapping && omp plugin upgrade mellos-mapping@mellos-mapping

Close the pane first (q in it): the watcher runs from the plugin copy, and on Windows an open file cannot be renamed away, so an upgrade attempted while a pane is open can fail with EPERM and leave the plugin cache empty — repaired by omp plugin install mellos-mapping@mellos-mapping --force. Then: the first command refreshes the catalog, the second reinstalls from it. omp also refreshes a catalog entry it has not updated for a day at startup, unless marketplace.autoUpdate is off — in the default notify mode that check writes its finding to the debug log only, so marketplace update is the step that makes an update visible. upgrade does not compare versions: it force-reinstalls whatever the catalog names, which is why a release is identified by its version bump rather than gated by it. Restart omp afterwards, and reopen a pane still showing the old bundle (q in it, then mmap_open again).

pi updates the package it installed, with no marketplace in between:

pi update npm:mellos-mapping

That is the npm source; a git source is reconciled to the ref your settings name by pi's own update, and a versioned spec (npm:mellos-mapping@0.27.0) is pinned and skipped. Restart the session afterwards: a session owns the map server process it started, so one still running keeps the copy it began with until it ends.

Upgrading from 0.19

0.20 moved the store out of .claude/ — the map belongs to this tool, not to one client — into .mellos/. The server and the watcher each perform the move once at startup, and print exactly one line on stderr when they do (mellos-mapping: moved the legacy .claude map store to .mellos/ — commit the move.):

Nothing is merged and nothing is overwritten: a project that already has a .mellos/ store (map, pages or config) is left untouched, whatever the legacy directory still holds. If you keep your maps in git, commit the move — git add -A .claude .mellos records it as renames rather than as a pile of deletions plus untracked files.

That one move is the only time either process touches .claude/. Afterwards the tools write nowhere but .mellos/, and never outside the project directory they resolved at startup.

ChatGPT App · Codex mode

This is Codex mode in the ChatGPT desktop app (also called Codex App). From the source branch run the following command; on chatgpt-app, omit the host argument. It configures the desktop skill, marketplace and eight MCP tools.

node install.mjs chatgpt-app

Start a new conversation. The desktop skill defaults to web-terminal: mmap_open {surface: "web-terminal", page: "<slug>"} starts a local service, then the AI opens its URL in the current conversation's right browser panel. The mmap terminal starts automatically, with its own font-size selector; no manual paste or Computer Use is needed. Graphical SVG, native terminal and Markdown remain available. With an older MCP schema, run node "<plugin root>/dist/web.mjs" "<project>" --terminal --page <slug>. A queued panel request does not prove that the user can see it. See desktop installation and limitations.

For Codex CLI inside Windows Terminal (not the desktop integrated terminal), run node <plugin root>/scripts/open-pane.mjs <project dir> — it splits the terminal window hosting the session, keeping keyboard focus on the conversation. If that window cannot be identified or focused, it reports failure without opening elsewhere. --window explicitly chooses a separate window. Add --page <slug> to open on a particular page — and with a pane already open, rerunning with --page retargets the pane belonging to this console. A map open in another session or a separate window does not count as this split. The pane auto-follows the page being written — the map the agent is operating on right now; press f to toggle that (a manual page switch also turns it off), or start with --no-follow. Elsewhere run node <plugin root>/dist/watch.mjs from the project directory in a second terminal (or any terminal split). Both take the same flags — see Pane flags.

Desktop Markdown map

When the user chooses the document surface, the skill uses mmap_open {surface: "markdown", page: "<slug>"} and opens the returned file beside the current conversation. The document embeds a colored SVG dependency map plus module details, evidence, and child-page links. It needs no web server, browser rendering process, Mermaid support, or additional runtime dependencies.

Successful MCP map writes regenerate enabled previews in .mellos/previews/; JSON remains the source of truth. Image nodes are static. File visibility and automatic viewer refresh belong to the desktop host. See the desktop map guide for regeneration, cache behavior, and limitations.

Optional interactive web viewer

An additional interactive web viewer is available with mmap_open {surface: "web", page: "<slug>"} or node "<plugin root>/dist/web.mjs" "<project directory>" --page <slug>. Open its returned URL in the host's right browser panel. It provides live updates, pan/zoom, hover and pinned details, search, dependency highlighting, filters, group overview, submaps and themes. Stop it with node "<plugin root>/dist/web.mjs" "<project directory>" --stop. Markdown/SVG and terminal workflows remain available; all surfaces share the same map data. See web viewer details.

Any MCP client

The server ships on npm, so any MCP client (Cursor, Windsurf, Zed, Gemini CLI, …) can run it with a standard stdio entry:

npx -y mellos-mapping

The map file lands in the client session's working directory (.mellos/map.json). Open the live pane from the same project:

npx -y -p mellos-mapping mellos-mapping-watch

The server picks its project directory in this order: MELLOS_MAPPING_CWD (an explicit override, for clients that spawn servers from a fixed directory), then CLAUDE_PROJECT_DIR (what Claude Code sets for plugin MCP servers), then the server process's own working directory. Set MELLOS_MAPPING_CWD when your client would otherwise start the server somewhere other than the project you are working in.

The skill/discipline layer is Claude Code + Codex specific; other clients get the eight mmap_* tools and the pane, and bring their own prompting.

Use

1. Ask Claude to build something non-trivial. The bundled skill has Claude declare the ghost design and keep the map current as it works.

2. The pane opens itself. Every write tells Claude whether anybody is actually looking (see Who is watching), and Claude opens or retargets the pane with mmap_open when nobody is — you never have to remember to. Open or close it yourself with mmap in any terminal, or /mellos-mapping:mmap in the conversation (Windows Terminal split on Windows, tmux split inside tmux, a Pebrel split inside Pebrel, or a printed command to run in any second terminal). On Windows the pane opens in the terminal window hosting YOUR session, even with several windows open; pass --window to put the map in its own dedicated window instead. Prefer --ascii if your font lacks box-drawing glyphs.

3. Watch nodes light up from the bottom. Interrupt when the picture worries you — that is what it is for.

On Linux and macOS, mmap_open and mmap automatically use tmux. The launcher targets the inherited TMUX/TMUX_PANE; if the tool process lost those variables, it discovers the single attached session on the default tmux server. The default is a right split that preserves input focus; --window creates a new tmux window. Repeated opens reuse the watcher bound to that source pane or session window.

For multiple attached sessions or a custom tmux socket, set these variables in the environment of the MCP server (restart it after changing them):

Inside Pebrel, mmap_open and mmap split the pane that hosts the conversation through Pebrel's runtime CLI (PEBREL_CLI). The launcher confirms which window that pane is in from its process tree, returns input focus to the conversation and types the watcher into the new pane's shell (PowerShell, cmd or a POSIX shell), which exits with it so the pane closes with the map. --window opens a new Pebrel window. Inside tmux, tmux owns the split.

Ambiguous sessions, detached sessions and missing tmux produce a concrete error and a fully quoted watcher command, including the project and requested page, to paste into any visible terminal. Map writes remain available; after an open failure the assistant retries only when the environment changes or you ask.

The pane is mouse-aware (xterm SGR any-event tracking — the same protocol htop and tmux speak):

Every other key is inert, on purpose: an escape sequence the pane does not know (F-keys, Home/End, PgUp/PgDn, Insert/Delete