--- 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 the four datasets below. Three principles apply across stacks; getting them wrong produces a misleading map: 1. **Edges live in two places** — direct calls in source, *and* dispatcher/ router calls whose targets are variables (config tables, route maps, dependency injection, dynamic dispatch). Resolve variables against config before declaring an edge unresolvable. 2. **The code↔storage join is usually external configuration**, not source — job/deployment descriptors map logical names to physical stores. 3. **Entry points usually live in deployment config**, not source — without parsing it, every top-level module looks unreachable. Extract: - **Program/module call graph** — direct calls (`CALL`, method invocations, `import`/`require`) *and* dispatcher calls (`EXEC CICS LINK/XCTL`, DI container wiring, framework routing, reflection/factory). Resolve variable call targets against route tables, copybooks, config, or constant pools. - **Data dependency graph** — which modules read/write which data stores, joined through the relevant config: `SELECT…ASSIGN TO` ↔ JCL `DD` (batch COBOL), `EXEC CICS READ/WRITE…FILE()` ↔ CSD `DEFINE FILE` (CICS online), `EXEC SQL` table refs (embedded SQL), ORM annotations/mappings (Java/.NET), model files (Node/Python/Ruby). Include UI/screen bindings (BMS maps, JSPs, templates) — they're dependencies too. - **Entry points** — whatever the stack's outermost invoker is, read from where it's defined: JCL `EXEC PGM=` and CICS CSD `DEFINE TRANSACTION` (mainframe), `web.xml`/route annotations/route files (web), `main()`/argv parsing (CLI), queue/scheduler subscriptions (event-driven). - **Dead-end candidates** — modules with no inbound edges. **Only meaningful once all the entry-point and call-edge types above are in the graph.** Suppress the dead claim for anything that could be the target of an unresolved dynamic call. A grep-only graph will mark most dispatcher-driven modules (CICS programs, Spring controllers, ORM-bound DAOs) dead when they aren't. If the source is fixed-column (COBOL columns 8–72, RPG, etc.), slice the code area and strip comment lines before regex matching, or you'll match sequence numbers and commented-out code. Save the script as `analysis/$1/extract_topology.py` (or `.sh`) so it can be re-run and audited. Have it write a machine-readable `analysis/$1/topology.json` and print a human summary. Run it; show the summary (cap at ~200 lines for very large estates). ## Render From the extracted data, generate **three Mermaid diagrams** and write them to `analysis/$1/TOPOLOGY.html` as a self-contained page that renders in any browser. The HTML page must use: dark `#1e1e1e` background, `#d4d4d4` text, `#cc785c` for `

`/accents, `system-ui` font, all CSS **inline** (no external stylesheets). Load Mermaid from a CDN in ``: ```html ``` Each diagram goes in a `
...
` block. 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 production telemetry is available (see `/modernize-assess` Step 4), annotate each step with its p50/p99 wall-clock. 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 `
` block in TOPOLOGY.html, add a `
    `
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 a browser.