Morgan Lunt bec8d7c93a
code-modernization: vendor d3, viewer robustness, status command, pipeline fixes
Viewer (assets/topology-viewer.html):
- inline a minified d3 subset (hierarchy/pack, zoom, selection,
  interpolateZoom, ease; ISC license) instead of loading from a CDN —
  the page is now fully self-contained and works on air-gapped networks
- handle duplicate node ids (unique-suffix; edges bind to the first
  occurrence) and store parent references directly, fixing
  level-of-detail and selection corruption with messy generated data
- share one reveal rule between drawing, edge culling, and hit-testing
  so edges no longer draw into collapsed containers
- pre-bucket edges by kind and keep a per-node adjacency map; the
  hover/selection pass no longer scans every edge each frame
- cancel in-flight fly-to animations when a new one starts; clamp
  fly-to zoom to the zoom extent; derive max zoom from the smallest
  leaf so deep estates stay reachable
- render dead-end candidates (new deadEnds field) with a dashed
  outline and a sidebar badge
- clicking a node during a flow walkthrough exits the walkthrough;
  search results clear on selection and Escape; surrogate-safe label
  truncation; clearer stats line; explicit empty-topology message

Commands:
- new /modernize-status: read-only progress report — artifact inventory
  with timestamps, staleness flags, secrets-hygiene checks, next step
- map: deadEnds in the topology schema; datastore names must be logical
  identifiers with credentials stripped from URLs/DSNs
- brief: read topology.json + .mmd files (not the interactive HTML);
  staleness check against inputs; effort unit aligned to person-months
- transform: secret-safe characterization-test prompt; diff -y fallback
  when delta is missing; credential-safe diff selection
- reimagine: target vision is everything after the first argument (was
  silently truncated to one word); masking rules in spec/scaffold/
  handoff prompts
- brief/transform/reimagine: human-approval gates phrased as explicit
  stop-and-wait instead of 'enter plan mode'
- preflight: delta in the tool table; brief added to the verdict list
- README: preflight/status in the workflow; legacy/ deny list also
  covers Write; plugin + marketplace descriptions updated
2026-06-09 08:48:04 -07:00

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---
description: Transform one legacy module to the target stack — idiomatic rewrite with behavior-equivalence tests
argument-hint: <system-dir> <module> <target-stack>
---
Transform `legacy/$1` module **`$2`** into **$3**, with proof of behavioral
equivalence.
This is a surgical, single-module transformation — one vertical slice of the
strangler fig. Output goes to `modernized/$1/$2/`.
## Step 0a — Toolchain check (fail fast)
Verify the build environment **before** planning, not when the tests
first run:
- **Target stack ($3):** runtime, package manager, and test framework all
respond (`java -version` + `mvn -v`, `node -v` + `npm -v`,
`python3 -V` + `pytest --version`, …).
- **Legacy stack (if equivalence tests will execute legacy code):** the
compiler/interpreter works on this codebase — run a syntax-only compile
of the module being transformed (e.g. `cobc -fsyntax-only`).
If anything is missing or the smoke compile fails, stop and report what
to install or fix — suggest `/modernize-preflight $1 $3` for the full
readiness report. Don't enter plan mode on a machine that can't run the
proof.
## Step 0b — Plan (HITL gate)
Read the source module and any business rules in `analysis/$1/BUSINESS_RULES.md`
that reference it. Then present the plan and **stop — write no code until
the user explicitly approves** (use plan mode if the session supports it):
- Which source files are in scope
- The target module structure (packages/classes/files you'll create)
- Which business rules / behaviors this module implements
- How you'll prove equivalence (test strategy)
- Anything ambiguous that needs a human decision NOW
Wait for approval before writing any code.
## Step 1 — Characterization tests FIRST
Before writing target code, spawn the **test-engineer** subagent:
"Write characterization tests for legacy/$1 module $2. Read the source,
identify every observable behavior, and encode each as a test case with
concrete input → expected output pairs derived from the legacy logic.
Target framework: <appropriate for $3>. Write to
`modernized/$1/$2/src/test/`. These tests define 'done' — the new code
must pass all of them. Follow your secret-handling rules: no credential
literal from legacy code becomes a fixture; substitute fake same-shape
values and read anything genuinely live from environment variables."
Show the user the test file. Get a 👍 before proceeding.
## Step 2 — Idiomatic transformation
Write the target implementation in `modernized/$1/$2/src/main/`.
**Critical:** Write code a senior $3 engineer would write from the
*specification*, not from the legacy structure. Do NOT mirror COBOL paragraphs
as methods, do NOT preserve legacy variable names like `WS-TEMP-AMT-X`.
Use the target language's idioms: records/dataclasses, streams, dependency
injection, proper error types, etc.
Include: domain model, service logic, API surface (REST controller or
equivalent), and configuration. Add concise Javadoc/docstrings linking each
class back to the rule IDs it implements.
## Step 3 — Prove it
Run the characterization tests:
```bash
cd modernized/$1/$2 && <appropriate test command for $3>
```
Show the output. If anything fails, fix and re-run until green.
## Step 4 — Side-by-side review
Generate `modernized/$1/$2/TRANSFORMATION_NOTES.md`:
- Mapping table: legacy file:lines → target file:lines, per behavior
- Deliberate deviations from legacy behavior (with rationale)
- What was NOT migrated (dead code, unreachable branches) and why
- Follow-ups for the next module that depends on this one
Then show a visual diff of one representative behavior, legacy vs modern:
```bash
delta --side-by-side <(sed -n '<lines>p' legacy/$1/<file>) modernized/$1/$2/src/main/<file>
```
(Fall back to `diff -y --width=160` if `delta` isn't installed.) Never
pick a credential-bearing line range for this diff, and mask any
credential-like literal quoted in TRANSFORMATION_NOTES.md — the notes
live in `modernized/` and get committed.
## Step 5 — Architecture review
Spawn the **architecture-critic** subagent to review the transformed code
against $3 best practices. Apply any HIGH-severity feedback; list the rest
in TRANSFORMATION_NOTES.md.
Report: tests passing, lines of legacy retired, location of artifacts.