claude-plugins/plugins/code-modernization/commands/modernize-map.md

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description: Dependency & topology mapping — call graphs, data lineage, batch flows, rendered as navigable diagrams

argument-hint:

Build a dependency and topology map of legacy/$1 and render it visually.

The assessment gave us domains. Now go one level deeper: how do the pieces connect? This is the map an engineer needs before touching anything.

What to produce

Write a one-off analysis script (Python or shell — your choice) that parses the source under legacy/$1 and extracts:

• Program/module call graph — who calls whom (for COBOL: CALL statements and CICS LINK/XCTL; for Java: class-level imports/invocations; for Node: require/import)
• Data dependency graph — which programs read/write which data stores (COBOL: copybooks + VSAM/DB2 in JCL DD statements; Java: JPA entities/tables; Node: model files)
• Entry points — batch jobs, transaction IDs, HTTP routes, CLI commands
• Dead-end candidates — modules with no inbound edges (potential dead code)

Save the script as analysis/$1/extract_topology.py (or .sh) so it can be re-run and audited. Run it. Show the raw output.

Render

From the extracted data, generate three Mermaid diagrams and write them to analysis/$1/TOPOLOGY.html so the artifact pane renders them live.

The HTML page must use: dark #1e1e1e background, #d4d4d4 text, #cc785c for <h2>/accents, system-ui font, all CSS inline (no external stylesheets). Each diagram goes in a <pre class="mermaid">...</pre> block — the artifact server loads mermaid.js and renders client-side. Do not wrap diagrams in markdown ` fences inside the HTML.

1. graph TD — Module call graph. Cluster by domain (use subgraph). Highlight entry points in a distinct style. Cap at ~40 nodes — if larger, show domain-level with one expanded domain.

2. graph LR — Data lineage. Programs → data stores. Mark read vs write edges.

3. flowchart TD — Critical path. Trace ONE end-to-end business flow (e.g., "monthly billing run" or "process payment") through every program and data store it touches, in execution order. If the observability MCP server is connected, annotate each batch step with its p50/p99 wall-clock from get_batch_runtimes.

Also export the three diagrams as standalone .mmd files for re-use: analysis/$1/call-graph.mmd, analysis/$1/data-lineage.mmd, analysis/$1/critical-path.mmd.

Annotate

Below each <pre class="mermaid"> block in TOPOLOGY.html, add a <ul> with 3-5 architect observations: tight coupling clusters, single points of failure, candidates for service extraction, data stores touched by too many writers.

Present

Tell the user to open analysis/$1/TOPOLOGY.html in the artifact pane.