# Tools — where the scripts are, and which ones can stop you

```
Status: Current
Owner: _null
Last reviewed: 2026-08-18
Governs: scripts/**, .githooks/**
Review trigger: Any script added to, removed from or repurposed in scripts/; any
                change to which of them gates a commit or a release
```

> A signpost, deliberately. Every project that adopts this template has a
> `docs/TOOLS.md`, so "read `docs/TOOLS.md` first" is an instruction that works
> without knowing anything about the project — which is the whole reason this
> file exists at a fixed path.

## The list is not here

**[`architecture/README.md`](architecture/README.md)** holds the table of what
this project has and what each script is. That is the one copy.

A second table here would be two records of one fact, and the other one would
never hear that a script was renamed. So this file answers the questions that
table does not, and points at it for everything else.

## Period has seven of them, and that is deliberate

The template this repository adopted ships around twenty scripts. Period took
six of them and wrote one of its own. `scaffold.sh` copies none of them on purpose — *"an unconfigured
`release.sh` landing in every new repository is a loaded gun, not a head
start"* — so each one is taken having been read and configured.

**The ones not taken were not forgotten.** `release.sh`, `deploy.py`,
`backup.sh`, `restore-check.sh`, `preflight.sh`, `healthcheck.sh`, `migrate.sh`,
`status.sh`, `dev.sh`, `audit-gate.mjs`, `release-notes.mjs`, `duplication.py`
and `dead-code.py` all assume a deployed Node or Postgres service with an npm
dependency tree and a URL. Period is an Android app that ships through Google
Play and has no server at all. A release here is an AAB and a Play Console
submission, so [`security/SECURITY_CHECKLIST.md`](security/SECURITY_CHECKLIST.md)
carries what `release.sh` would have gated.

Two were deferred rather than declined:

- **`verify.sh`** — worth having once there is a real check suite to aggregate.
  Today `./gradlew check` is the whole answer and wrapping it would add a layer
  that could only be wrong.
- **`check-env.sh`** — its SPEC ships empty and exits `2` until it has entries,
  and Period has no environment variables yet. It gets taken with the first
  signing or Play credential, which is exactly the moment it becomes worth
  running.

**The seventh is `schema-guard.sh`, and it is this project's own.** It clears
the bar in *Adding one* below the hard way: it exists because the check it
replaces was proved green over exactly the failure it claimed to catch. Its
header carries that proof.

If this project later grows a script the template already has, take that one
rather than writing a new one — the arguments in its header are the part that
took the longest.

## Which ones can stop you

Not in a table, because the honest answer lives in each script's own header and
would go stale here. The rule that matters:

**Exit code `2` is never a pass.** These scripts distinguish "the check ran and
found nothing" from "the check did not run", because those look identical from
the outside and only one of them is evidence. A hook or a CI step that treats a
`2` as success has quietly turned the check off. Each script states its codes at
the top; read them there.

**And a `2` is not automatically a failure either — it is a question.** The
pre-commit hook learned this the hard way: `secrets.sh` exits `2` on a commit
that only *deletes* files, because a deletion has no added lines to scan, and
that is the correct answer. The hook treated every non-zero as a refusal and
printed *"possible credential in the staged changes"* over a plain `git rm`, so
deletion-only commits were impossible and the reason given was a security
problem that did not exist.

The rule that came out of it: **on a `2`, ask whether the check could have had
anything to look at.** The hook now refuses a `2` whenever the staged diff adds
lines — because then the scanner did have input and checking nothing is exactly
the failure `2` reports — and accepts it, saying so, when the diff only removes
content. Both directions are proved with `prove-guard.sh`-style injections
before either is believed.

The hooks are the other place work gets stopped:
[`architecture/githooks/README.md`](architecture/githooks/README.md) has the one
install command and the table of what each hook runs. Note that **`post-commit`
pushes**, and that `pre-commit` here runs Gradle rather than the template's
TypeScript typecheck.

## Where to start in a fresh clone

1. `git config core.hooksPath .githooks` — per clone, every time, and an
   uninstalled hook fails silently.
2. `bash scripts/secrets.sh --tracked` — the one-time audit of what is already
   committed. The staged-diff mode is for the hook; this mode is for the day you
   clone.
3. `./gradlew test` — the prediction acceptance tests run on the JVM, so this
   needs no emulator and should be fast.
4. [`architecture/GUARDS.md`](architecture/GUARDS.md) — how to write a check that
   can actually fail, before you write one. `scripts/prove-guard.sh` performs its
   first rule.

## Adding one

Put it in `scripts/`, give it a header saying what it does and **which incident
motivated it**, state its exit codes, and add a row to
[`architecture/README.md`](architecture/README.md)'s table — this file's
`Review trigger` fires on exactly that.

The bar, from the scripts that are already here: **done by hand three times, or
once with a consequence.** A script written before either of those has no
failure to describe in its header, which is the part that stops the next person
deleting it.
