reverse-engineer

# Reverse Engineer

Reverse-engineer an external system into two things: a **mechanically-verifiable teardown** (feature inventory + registry + specs, optionally a security audit) and a **steal-map** — what to adopt into our surfaces, what to leave behind. The teardown is the evidence; the steal-map is the decision. Separating them works because a decision row that must cite a registry entry can be re-checked by anyone, while a decision made from impressions cannot be re-checked by its own author. The original failure mode this skill exists to prevent: reading a competitor's README and "deciding" from vibes.

**Triggers:** "reverse-engineer X", "tear down Y", "what should we steal from Z", "evaluate competitor/upstream", "should we fork/adopt/build-native".

## ⚠️ Constraints — Hard Guardrails (MANDATORY)

- Only operate on code/binaries you own or have **explicit written authorization** to analyze — this matters because unauthorized teardown is the legal/IP line.
- Do not provide steps to bypass protections/ToS or to extract proprietary source/system prompts.
- Do not output reconstructed proprietary source or embedded prompts (index only; redact in reports) — to prevent reproducing protected IP.
- Redact secrets/tokens/keys if encountered; run the secret-scan gate over outputs to prevent credential leakage.
- Always separate **docs say** vs **code proves** vs **hosted/control-plane**.

## Phase 1 — Mechanical teardown (the script)

Produce evidence, not vibes. The script clones (pinned), scans CLI/config/artifact surface, and writes a feature inventory + machine-checkable registry + spec set.

```bash
python3 skills/reverse-engineer/scripts/reverse_engineer.py <product> --mode=repo \
  --upstream-repo="https://github.com/org/repo.git" --upstream-ref=v1.0.0 \
  --output-dir=".agents/scratch/reverse-engineer/<product>/"
```

Binary mode requires `--authorized` (see Invocation Contract + Self-Test). Use the bundled demo fixture if you lack authorization for a real binary.

## Phase 2 — The steal-map (the decision)

Map each capability the teardown found onto **our** surfaces. This is the part that turns research into a decision. Emit `.agents/scratch/reverse-engineer/<product>/steal-map.md` with a table; every row cites the teardown evidence **and** the matching surface in our repo.

The mechanical script intentionally stops after validating Phase 1. It cannot
truthfully decide whether our live tree has, lacks, or should adopt a capability.
The caller authors `steal-map.md` from the generated registry plus a fresh read
of our repository, then runs the complete-output validator below. A missing or
malformed map is therefore an incomplete skill result, not a script success
silently relabelled as a decision.

| Their capability | Our surface today | Verdict |
|---|---|---|
| `<feature>` | `<our file / skill / CLI, or "none">` | **have** / **gap** / **steal** / **park** / **reject** |

Verdict rules (hard-won — apply them, do not skip):

- **steal** — we lack it and it advances our core. Steal the *pattern*, not the storage engine: re-express in our primitives, never vendor their runtime.
- **park** — real, but it's substrate we deliberately delegate (e.g. orchestration per ADR-0009) or downstream of an unproven bet. Name it, don't build it.
- **reject** — it conflicts with our doctrine (e.g. a self-reported completion edge where we require a verdict — "no verdict = not done").
- **have** — we already do this; confirm it still holds, move on.
- **gap** — we should have it and don't. These are the steal candidates.

Discipline that makes the map trustworthy:

- **Independently checked, not self-report.** Get facts on *how* they implement
  each capability from code, cross-checked by a fresh reader — never from a
  README or one context's summary. Model family is optional metadata, not a
  trust requirement.
- **Probe the real state, don't argue from stale.** Re-verify our side against the live tree before calling something a gap; every "X is missing" carries the search that proved it.
- **The steal is the pattern, not the platform.** Their robustness is usually one idea (unification, a gate, a reconcile loop). Steal the idea; leave the scaffolding.

## Route one-way-door adoptions into planning

If adopting a steal is a **one-way door** (an architecture fork, a new bounded
context, or a migration), do not decide it here. Hand the steal-map to Plan.
Dueling Idea Genies or Premortem may challenge the choice as advisory
evidence. Plan alone shapes the selected option in the existing intent source;
neither strategy grants readiness or continuation authority.

## Invocation Contract

Required: `product_name`. Common flags: `--mode=repo|binary|both`, `--upstream-repo`, `--upstream-ref` (requires the selected checkout to be at that exact commit and records its resolved SHA in `clone-metadata.json`), `--local-clone-dir` (selects that exact tree, including a non-Git tree; it never falls back to the caller's checkout), `--output-dir` (default `.agents/scratch/reverse-engineer/<product>/`), `--security-audit`, `--materialize-archives` (authorized-only opt-in; embedded-archive extraction is off/index-only by default), `--authorized` (mandatory for binary mode — refuses without it). Full list: `python3 skills/reverse-engineer/scripts/reverse_engineer.py --help`.

## Output Specification

Phase-1 teardown under `output_dir/`: `feature-inventory.md`, `feature-registry.yaml`, `feature-catalog.md`, `spec-architecture.md`, `spec-code-map.md`, `spec-clone-vs-use.md`, `spec-clone-mvp.md`, plus `spec-cli-surface.md` only when a CLI is detected. `clone-metadata.json` is written whenever an upstream repo/ref is selected and binds the exact analyzed commit, including an already-present checkout. Security mode adds `output_dir/security/`: `threat-model.md`, `attack-surface.md`, `dataflow.md`, `crypto-review.md`, `authn-authz.md`, `findings.md`, `reproducibility.md`, `validate-security-audit.sh`. Phase-2 adds the calle