diagram_listLABSCO SUMMARY
Both of you editing one diagram session, with identities that survive a rewrite.
The hard problem in agent-edited diagrams is churn: rewrite the Mermaid and every reference breaks. Nereid keeps stable ids across a bulk replace when the fingerprints still match, and tells you which cross-references were dropped. The shared attention state is the other half - it is what makes the agent's edits land where you are actually looking.
What it is
A diagram workspace with two front ends onto one session folder. A terminal UI for a person, and typed MCP tools for an agent; both read and write the same Mermaid sources, cross-references and walkthroughs on disk.
What you get
- Five diagram families - sequence, flowchart, class, entity-relationship and Gantt - parsed, rendered as text, and persisted
- Diagram lifecycle and reads: list, open, delete, read, stat, abstract syntax tree, slice, text render and diff
- Structured mutation for sequence and flowchart diagrams, plus a bulk Mermaid replace that keeps stable identities when fingerprints still match and reports which references went dangling
- Walkthroughs with their own list, read, node and diff tools, and structured edits
- Cross-references between diagrams, with neighbours, adding, removing and object reads
- Graph queries: reachability, paths, cycles, unreachable nodes, dead ends, degrees, and message search or trace on a sequence
- Shared attention state, so the agent can see what the human is looking at and say what it is looking at
Requirements
Rust 1.85 or newer for a Cargo install; Homebrew, GitHub releases, Docker and an npm wrapper needing Node.js 18 are also available. A session folder is the unit of work and the source of truth - Mermaid sources, metadata index, walkthroughs and text renders all live there. In TUI mode the MCP server is served over streamable HTTP on port 27435; with the mcp flag and a session path it runs over stdio instead. The licence is source-available and noncommercial: commercial, product or internal business use needs written permission.
Setup effort
One command — cargo install nereid
USE CASES
01
Letting an agent update a diagram you are reading
Keep the terminal UI open while the agent connects over HTTP; both act on the same session folder, and attention state keeps you pointed at the same place.
02
Making a local edit without rewriting the diagram
Apply structure operations for the alt or loop block you want changed, rather than regenerating the whole Mermaid source.
03
Replacing a diagram wholesale but keeping references
Use the Mermaid replace path; matching fingerprints preserve ids and the response names what was preserved, dropped or newly created.
04
Asking structural questions about a flowchart
Query reachability, paths, cycles and dead ends instead of tracing arrows by eye.
05
Keeping diagrams linked to each other
Add cross-references between related nodes and walk the neighbours when following a thread across diagrams.
47 tools
Listed in project docs. Your client may show a different list.
diagram_currentdiagram_opendiagram_deletediagram_readdiagram_statdiagram_get_astdiagram_get_slicediagram_render_textdiagram_diffdiagram_create_from_mermaiddiagram_replace_from_mermaiddiagram_propose_opsdiagram_apply_opswalkthrough_listwalkthrough_currentwalkthrough_openwalkthrough_readwalkthrough_statwalkthrough_get_nodewalkthrough_render_textwalkthrough_diffwalkthrough_apply_opsattention_human_readattention_agent_readattention_agent_setattention_agent_clearfollow_ai_readfollow_ai_setselection_readselection_updateview_read_statexref_listxref_neighborsxref_addxref_removeobject_readroute_findseq_messagesseq_searchseq_traceflow_reachableflow_pathsflow_cyclesflow_unreachableflow_dead_endsflow_degreesBEFORE YOU INSTALL
What to know first
Tools you get
47 tools named in the project's documentation.
Requires
Rust 1.85 or later
INSTALLATION
Connect your client
Server setup
Configuration file
JSON
{
"mcpServers": {
"nereid": {
"command": "nereid",
"args": [
"--mcp",
"--session",
"<YOUR_PATH_TO_SESSION>"
]
}
}
}<YOUR_PATH_TO_SESSION> is the absolute path of your session folder (the README creates one with mkdir my-session).
cargo
TERMINAL
cargo install nereid
