| name | fabrico-reverse-spec |
| description | Reverse-engineer a platform-agnostic `SPEC.md` from an authorized running web app. |
Invocation portability: $fabrico-* below means the discovered entry workflow. Use the unqualified name for repository or filesystem installs and $fabrico-collections:fabrico-* for plugin installs.
Input
Use the user’s current request as the workflow input. Expected context: <url of the running app> [login/scope notes].
Goal
Produce a faithful, behavioral SPEC.md for an existing web application by observing it in a real browser — so it
can be rebuilt on a modern stack or ported to mobile. You describe what the app does (screens, data, roles,
flows, integrations), not how its legacy code is written.
Required skills
Load and follow these before starting:
fabrico-reverse-engineering-spec — the end-to-end capture → spec procedure (and its references/playwright-capture.md).fabrico-task-extracting — for turning observed behavior into well-formed epics and user stories.
Workflow
- Confirm inputs. Read the URL from
the user’s request. If no URL is given, or a required area is behind a login you
can't pass, ask the user directly to get the URL / credentials / scope. This is the one true blocker —
don't guess behind auth.
- Verify access. Open the app with the playwright MCP server. If the playwright server is
not connected, tell the user to enable it (it's defined in
.mcp.json) and stop.
- Run the reverse-engineering process from the
fabrico-reverse-engineering-spec skill: route inventory →
per-screen capture → infer data model, roles, flows, integrations → synthesize features into user stories with
acceptance criteria. For a large app, you may delegate non-overlapping section crawls in batches of at most five
concurrent workers from a user-facing thread, or four when this caller itself has a parent. Every worker returns
evidence to this calling thread and must not spawn another worker.
- Write the artifacts:
SPEC.md (platform-agnostic, with a Target (fill at build time) section and a
Source mapping appendix), plus legacy-inventory.md, legacy-capture/ (screenshots), and
reverse-spec-notes.md (open questions/assumptions).
- Coverage gate. Confirm every inventoried screen maps to a story or is explicitly out-of-scope. Then present a
short summary and the list of open questions for the user to confirm.
Output
SPEC.md — compatible with $fabrico-autopilot SPEC.md and $fabrico-modernize SPEC.md.legacy-inventory.md, legacy-capture/, reverse-spec-notes.md — evidence and open questions.
Constraints
- Read-only inspection: never submit destructive actions (deletes, payments, real emails) against the live app;
prefer staging/localhost. Only inspect apps the user owns or is authorized to analyze.
- Base every acceptance criterion on observed behavior. Flag uncertainties in
reverse-spec-notes.md — do not
invent features, and do not silently drop ones you saw.
