arch-adopt git:20260929.2ad8a02A

Immutable. This exact content never changes and is served at /api/v1/blob/c8284b80bff752d4.

---
name: arch-adopt
description: >
  Installs or updates this architecture's `.claude/` inside a Java project — norms with
  their globs derived for the project's own packages, the development skills and agents,
  the hook and its schema. Use when the project was never generated by `/init-project`
  and should adopt the architecture, or when a project already has it and should pull a
  newer version. Explicit invocation only.
argument-hint: "[--ref <tag|sha|main>] [--source <local path>] [--blueprint <id>]"
disable-model-invocation: true
allowed-tools: Read, Write, Edit, Bash, Glob, AskUserQuestion
model: opus
---

# Arch Adopt

Pulls this architecture into the project the session is rooted at. One operation, two
starting states: the project has no `.claude/` of this shape yet (install), or it has one
and is behind (update). The difference is the provenance stamp, not a different command.

**Writes nothing by itself.** Every file is written by `ArchHook.java export`, from the
copy it just fetched. This skill decides *which* source, *which* blueprint, and *whether
it is safe to write* — three questions a deterministic mode cannot answer — and then
gets out of the way.

## Procedure

### 1 · Refuse to write over uncommitted work

```bash
git rev-parse --is-inside-work-tree && git status --porcelain
```

Not a git repository, or the output is not empty → **stop**. An update overwrites, and
`git diff` is how the person reviews it and `git checkout` is how they undo it; without a
clean tree neither works. Say that, and say what to run (`git init` and a first commit,
or commit/stash what is pending). Don't offer to commit for them.

### 2 · Resolve the source

Everything this procedure downloads goes in one directory, named once here and used by
every step below — an environment that hands out its own temporary directory needs to
change this line and no other:

```bash
SRC=${SRC:-/tmp/arch-src}
```

`base_url`, `git_url`, `auth_env` and `default_ref` come from the `source` block of
`.claude/schemas/extensions.json`. **Never write any of those four values into a command
from memory** — that is the whole reason they are data. Three places to look, in order,
and the third is not a fallback but the normal case on a first install:

1. **This project's copy**, when it has one with a `source` block.
2. **The plugin's copy** — but the published plugin ships only its `SKILL.md`, so this
   path usually finds nothing. Not a bug: the architecture is fetched, not vendored.
3. **The source's copy, fetched.** The plugin's `.plugin-source.json` carries `raw_url`
   and `ref`, which is enough:

   ```bash
   curl -sS --fail -L "<raw_url, {ref} and {path} replaced for .claude/schemas/extensions.json>" \
     -o "$SRC-extensions.json"
   ```

   A project generated before the `source` block existed has a `.claude/schemas/extensions.json`
   without one — `grep '"source"'` comes back empty. That is case 3, not a broken project.

With `--source <path>`, skip the rest of this step and the next: that path is `$SRC`,
which is how an unreleased change is tested.

```bash
git ls-remote --tags --refs --sort=-v:refname <git_url> | head -1
```

The newest tag is the default. `--ref <tag|sha|main>` overrides it; `main` is only ever
used when asked for explicitly, because it moves. No tags at all → say so and use `main`,
stating that the stamp will record a moving ref.

### 3 · Fetch

```bash
AUTH=()
[ -n "${GH_TOKEN:-}" ] && AUTH=(-H "Authorization: Bearer $GH_TOKEN")
curl -sS --fail --retry 3 --retry-all-errors --max-time 120 -L "${AUTH[@]}" \
  "<base_url, {ref} replaced>" -o "$SRC.tgz"
mkdir -p "$SRC" && tar xzf "$SRC.tgz" --strip-components=1 -C "$SRC"
```

`$GH_TOKEN` is the variable `source.auth_env` names — read the name from the file, and
never print the value. The header is only sent when the variable is set: a public source
needs no credential. `--fail` is what turns an HTTP error into an error; without it a 404
page lands in the tarball and `tar` fails with something that says nothing about access.

### 4 · Decide the blueprint

Three states, not two. Read them in this order.

**Update** — `.claude/.arch-provenance.json` exists: read `blueprint` from it and use it.
Don't re-ask; a project doesn't change architecture by updating. `--blueprint` overrides,
and then say plainly that this rewrites every rule's territory. When the id names a
blueprint the source does not have, the project's own copy at
`.claude/blueprints/<id>/<id>.yaml` is the one to use — that is why the export wrote it
there.

**Adopted before the stamp existed** — no `.arch-provenance.json`, but
`.claude/rules/00-index.md` is present. The project already has an architecture and is not
a fresh install: `00-index.md`'s own paragraph names the blueprint it was generated from.
Read it, show it, and ask for confirmation in one question — never re-run the detection
below and never re-ask from a blank slate. Every project generated before D54 is in this
state, and asking it to pick an architecture it already has is how it ends up with two.

**Install** — no stamp and no `00-index.md`. Read the project's package layout and compare
it with the blueprints in the fetched source:

```bash
find src/main/java -type d -mindepth 3 | sed 's|src/main/java/||' | tr '/' '.' | sort
ls "$SRC/.claude/blueprints"
```

Match those packages against each blueprint's `packages.map` **values**, and offer the
closest one first. Then use `AskUserQuestion` — the choice is the user's, not yours:

1. the detected blueprint, named, with the two or three packages that matched;
2. the other blueprints that have a `<id>.yaml`;
3. build a `custom.template.yaml` — **and say what it costs**: the architecture is then
   described by a file nobody has generated a project from, every rule's territory comes
   from it, and a wrong `packages.map` leaves norms silently unloaded. Offer it, don't
   steer to it.

**Near-match is its own case, and it is the dangerous one.** When the layout matches every
package of a blueprint except one or two, say so before anything else: name the packages
that differ, on both sides, and ask whether they are the same role under two names. A
blueprint that gained a key after this project was generated looks exactly like this —
`application.shared` versus an `application/service/` the executor once invented — and
accepting the blueprint as-is rewrites every norm to a package the code does not have.
Nothing breaks that day; the next `/new-feature` creates the second package. Options:
adopt the blueprint and rename the code, or build a variant of it (option 3) that keeps
the project's own names.

Option 3 chosen: copy `$SRC/.claude/blueprints/custom-template/custom.template.yaml`
to `$SRC/.claude/blueprints/<name>/<name>.yaml`, fill `packages.map` and
`architecture_paths` from the layout you just read, and use `<name>` as the id. The export
copies the blueprint it used into `.claude/blueprints/<id>/<id>.yaml` inside the project,
so the variant survives the temporary directory and the next update can resolve it.

### 5 · Write

```bash
CLAUDE_PROJECT_DIR="$SRC" java "$SRC/.claude/hooks/ArchHook.java" export . \
  --blueprint <id> --ref <ref>
```

Add `--dry-run` first whenever the project already has files at those paths, and show the
user the list before the real run. Read the mode's own output: a line reporting a
surviving citation to `decisions/` or `blueprints/` means a dead path just landed in the
project, and it belongs in the report, not in silence.

### 6 · Verify, then hand the diff over

```bash
java .claude/hooks/ArchHook.java schema </dev/null
java .claude/hooks/ArchHook.java doctor
git status --short
```

`schema` keeps the `</dev/null`: it is one of the modes the runtime invokes as a hook, so
it reads a JSON payload from stdin and waits for one when nothing closes it. `export`,
`doctor` and `compose` do not read stdin at all.

`schema` must exit 0. `doctor`'s `Provenance` line should read "unchanged since" — it
compares the stamp's per-file digests, so anything it lists right after an export is
something the export could not write. Do **not** commit: the diff is the user's review.

## Report

```
✅ <installed | updated> — blueprint <id>, ref <ref> (<short sha>)

Source ....... <base_url host>, fetched at <time>
Files ........ <n> written · <n> unchanged · <n> overwritten
Warnings ..... <none | the surviving-citation lines, verbatim>
Schema ....... <exit 0 | the failure>
Provenance ... <the doctor line>

Review: git diff · Undo: git checkout -- .claude
Next: /arch-doctor for the full diagnosis
```

On an update that overwrote files the user had edited, list them. `doctor`'s Provenance
line names them **before** the export too — run it first when the project already has a
stamp, and put that list in front of the user before writing anything.

## Why this is a manually-invoked skill

Form 2 (`disable-model-invocation: true`): it rewrites `.claude/` from a remote source,
so it may only run when a person asks for it by name — axis 2 of the interview, "a human
command inside the target project". The closest rejected form was Form 1: an
auto-invocable skill with this description would fire on any sentence about updating the
architecture, and the first thing it does is overwrite the norms the session is reading.
The transformation itself is deliberately **not** here — it is `ArchHook.java export`,
Form 7c, because it runs unattended on other people's machines and the same input has to
produce the same tree.

Pinned to `opus`: it merges into a project it did not write, and may write the only copy of that project's blueprint (`@.claude/decisions/0081-skill-model-required-per-class.md`).

## Contract

**Class:** build — the territory is `skill_classes.build`'s override for this skill in
`@.claude/schemas/extensions.json`: the target project's `.claude/` tree and its
`.gitignore`, nothing else. `ArchHook.java guard` enforces it.

**Unfiltered Bash:** adoption fetches the source (`git ls-remote`, `curl`, `tar`), inspects the worktree (`git status`, `git rev-parse`, `find`), and runs `java … export` — spread over two tools that fetch from the network and a command list that grows with the source's layout. Writes stay under `guard`/`guard bash`, and a force push is blocked by `guard bash` (`guard.force_push`).

**Reads** `.claude/schemas/extensions.json` (the `source` block — never a URL from
memory), `.claude/.arch-provenance.json` when it exists, `src/main/java/**` to detect the
layout, and the fetched source's `.claude/blueprints/*/*.yaml`.

**Writes** nothing directly in the project: `ArchHook.java export` does, and the list of
what it writes is the `export` block of the fetched `extensions.json`. May write
`$SRC/**` — the fetched tree, including a `custom.template.yaml` built in step 4.

**Refuses** a dirty worktree, a directory that is not a git repository, and a fetch it
cannot authenticate. Never prints the value of `source.auth_env`, and never commits.

**Travels into the project** — unlike `project-bootstrap` and `init-project`, which only
serve before the project exists. This one is how a project updates itself once the plugin
that delivered it is gone, so it is in `export.skills.include`.

**Hands off to** `/arch-doctor` for the diagnosis, and to the user for the diff.