--- 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. Cover the parse targets that are real for the stack you're looking at — these are the ones LLMs reliably miss: - **Program/module call graph** — who calls whom. - COBOL/CICS: `CALL '...'` and `EXEC CICS LINK/XCTL PROGRAM(...)`. Most `PROGRAM(...)` targets are **data-names, not literals** — resolve them against working-storage `VALUE` clauses and any menu/route copybooks before declaring an edge unresolvable. - Java: class-level imports/invocations. Node: `require`/`import`. - **Data dependency graph** — which programs read/write which data stores. - COBOL batch: `SELECT ... ASSIGN TO ` joined with JCL `DD` statements (this is the *only* way to attribute file I/O to a program). - COBOL/CICS online: `EXEC CICS READ/WRITE/REWRITE/DELETE/STARTBR/READNEXT/ READPREV ... FILE(...)` joined with `DEFINE FILE` in the CSD. - DB2: `EXEC SQL ... END-EXEC` table references — *not* JCL DD; DB2 access is via plan/package binds. - BMS: `SEND MAP`/`RECEIVE MAP` ↔ map source under `bms/` and copybooks under `cpy-bms/` (or wherever the maps live). - Java: JPA/MyBatis entities & tables. Node: model files. - **Entry points** — whatever the stack's outermost invokers are. Mainframe: JCL `EXEC PGM=` steps **and** CICS `DEFINE TRANSACTION ... PROGRAM(...)` from the CSD — without the CSD, every online program looks unreachable. Web: HTTP routes. CLI: argv parsing. - **Dead-end candidates** — modules with no inbound edges. **Only trust this once the entry-point and call-edge types above are all in the graph**, and suppress the dead claim for any module that could be the target of an unresolved dynamic call. A naive grep-only graph will mark most CICS programs dead. For COBOL fixed-format, slice columns 8-72 and skip `*` indicator lines (column 7) 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.