reverse-engineer git:20261025.a376884A

Immutable. This exact content never changes and is served at /api/v1/blob/bdd45afc16cd4386.

---
name: reverse-engineer
description: 'Tear down a competitor''s repo or product into a feature inventory and adoption choices. Use when: comparing us to another tool or asking what to steal.'
practices:
- legacy-code-seams
- ddd-bounded-context
- adr
hexagonal_role: supporting
consumes: []
produces:
- '.agents/scratch/reverse-engineer/*/'
context_rel: []
skill_api_version: 1
user-invocable: true
context:
  window: fork
  intent:
    mode: task
  sections:
    exclude:
    - HISTORY
metadata:
  dependencies: []
  capabilities: [reverse_engineer]
  effects: [clone_upstream_repo, authorized_binary_execution, write_teardown_artifacts]
  canonical_status: canonical
  disposition: keep_specialist
  tier: execution
  internal: false
output_contract: validated phase-1 teardown directory, followed by a caller-authored and validated phase-2 steal-map.md
---
# Reverse Engineer

Reverse-engineer an external system into two things: a **teardown** (feature
inventory, a registry of where to read, CLI and contract specs, optionally a
security audit) and a **steal-map** (the decision: what to adopt into our
surfaces and what to leave behind). A decision row that must cite evidence can
be re-checked by anyone; a decision made from impressions cannot be re-checked
by its own author. Deciding from a competitor's README is the failure this
skill exists to prevent.

## ⚠️ 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. The output validator runs this skill's `scripts/security/scan_secrets.sh` over the whole output dir in every phase; a hit fails it until you redact.
- Always separate **docs say** vs **code proves** vs **hosted/control-plane**.

## Evidence rules

- **Tag every capability by its source.** `code`: their source or binary
  shows it; cite the file:line (for a binary, the teardown output line) you
  opened and record what the code actually does, which is often narrower than
  the claim. `docs`: a README, doc page or announcement says it; unverified.
  `hosted`: a service or control plane you cannot inspect.
- **The registry is an index, not evidence.** It lists where to read. In repo
  mode its groups start `impl: unclassified` (binary mode writes `client` groups
  anchored to `binary-symbols.txt`, still not `code` evidence); `client` or
  `mixed` needs anchors, and `control-plane` means `hosted`. A registry entry
  alone never makes a row `code`.
- **No code access, no steal.** With only docs, a README or a landing page,
  every row about their implementation is `docs` and unverified. It can be
  `gap`, `park` or `reject`, never `steal`.
- **Prove our side on the live tree.** A `have` row cites our file. Every
  "missing" row carries the search that proved it (command and scope). Check
  what our current stack already offers before calling anything missing.
- **Re-open before a steal.** Re-open each cited file before marking `steal`;
  a summary from memory is not evidence.
- **The steal is the pattern, not the platform.** Their robustness is usually
  one idea (unification, a gate, a reconcile loop). Re-express it in our
  primitives; never vendor their runtime or storage engine.

## Phase 1 — teardown

With an authorized clone or binary, the script clones (pinned), scans the
CLI/config/artifact surface, writes the inventory, registry and specs, and
validates the teardown:

```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>/"
```

The clone lands in `.tmp/<product>/` under the current directory unless
`--local-clone-dir` names another place; keep it out of your commits. Binary
mode requires `--authorized`; without authorization for a real binary, run
this skill's `scripts/self_test.sh`, which builds a demo binary (needs Go). Flags, the full
output list, fixtures and tests are in [the invocation reference](references/invocation.md).

Without code access (only a README, docs site or landing page), skip the
script: build the inventory and steal-map by hand with each row tagged `docs`
or `hosted`, and say that no teardown validator ran. When the code is readable
but the script cannot run on it, read the code directly and cite `file:line`
for each `code` row; the validator gap still gets reported.

## Phase 2 — steal-map

Map each capability onto **our** surfaces in
`.agents/scratch/reverse-engineer/<product>/steal-map.md`. The script stops
after validating Phase 1; it cannot truthfully decide whether our live tree
has, lacks, or should adopt a capability. The caller authors the map from the
teardown, the code it points to, and a fresh read of our repository. A missing or malformed map is an
incomplete skill result, not a script success relabelled as a decision.

| Their capability | Our surface today | Verdict |
|---|---|---|
| `<feature>` (code: `<file:line>`), (docs) or (hosted) | `<our file / skill / CLI>`, or "none" plus the search that proved it | **have** / **gap** / **steal** / **park** / **reject** |

Each row gets exactly one verdict:

- **have** — our live tree already does it; cite the file and confirm it still holds.
- **steal** — we lack it, `code` evidence shows how they do it, and it advances
  our core. Take the pattern, re-expressed in our primitives.
- **gap** — we lack it and would want it if it holds up, but steal is not
  earned: their mechanism is `docs` or `hosted` only, or its value to our core
  is unshown. Name the evidence that would decide it.
- **park** — real, but deliberately not ours to build now: substrate we
  delegate (for AgentOps, ADR-0009 keeps scheduling, supervision and queues
  external) or downstream of a bet we have not made. Name it, don't build it.
- **reject** — conflicts with our doctrine (e.g. a completion edge with no check
  behind it, where we require checks and CI, plus one fresh judgment for a
  costly mistake).

When two seem to fit, reject beats park, and park beats steal or gap; between
steal and gap, the evidence rules decide.

## Validation and handoff

After authoring `steal-map.md`, validate the complete output with
`$output_dir`, `$security_audit`, `$sbom`, and `$upstream_ref_set` (each
numeric flag `0|1`):

```bash
bash skills/reverse-engineer/scripts/validate-output.sh \
  --output-dir "$output_dir" --phase complete \
  --security-audit "$security_audit" --sbom "$sbom" \
  --upstream-ref-set "$upstream_ref_set"
```

It fails any table row without a source tag or one of the five verdicts, and
any `steal` without `code` evidence; with an upstream ref it requires the
resolved commit in `clone-metadata.json`. It must exit 0 before handoff, or the
report says it did not run (docs-only mode).

If adopting a steal is a **one-way door** (an architecture fork, a new bounded
context, a storage or data migration), do not decide it here: hand the
validated steal-map to [Plan](../plan/SKILL.md), which shapes the selected
option in the existing intent source. [Idea Genie](../idea-genie/SKILL.md) duel
mode or [Premortem](../premortem/SKILL.md) may challenge it as advisory
evidence; neither grants readiness or continuation authority. Ordinary `have`,
`park` and `reject` rows are evidence-backed terminal decisions.

For general exploration rather than one external system, use
[Research](../research/SKILL.md). The scenarios in
[reverse-engineer.feature](references/reverse-engineer.feature) document the
behavior; this skill's `scripts/validate.sh` and `scripts/self_test.sh` check it.