Files
plainpages/AGENTS.md
T

366 lines
28 KiB
Markdown
Raw Blame History

This file contains ambiguous Unicode characters
This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.
# AGENTS.md
Guidance for AI agents and contributors working in this repo. Read `README.md` for
commands and layout.
## Prose discipline
Every word in this repo is read again on every future task, so prose is a recurring cost. On **any**
change, sweep the prose you touched — this file, `README.md`, the example READMEs, and code
comments — and cut it back to what a competent reader could not infer:
- **Delete history.** Git holds it. No "this moved from X", "used to be Y", "was tried and
rejected", "(declined twice)", dated changelog entries, or the symptom that prompted a fix. Record
the decision and the reason it *currently* turns on, nothing else.
- **Delete restatement.** A comment that says what the adjacent line says, a doc paragraph that
re-explains a table above it, a file-map entry that expands the filename. The fix is deletion,
not trimming.
- **Delete the self-evident** and anything already stated once elsewhere. **One home per fact**
link to it instead of repeating it; the same sentence in five files is five chances to drift.
- **Give every accepted risk an expiry** ("valid while X"), and delete the entry once X stops
holding.
- **Keep** the surprising why, the footgun, the invariant, the external constraint, and the one-time
setup a reader cannot dig out of the code. Once a line has earned its place, make it short and
information-dense.
Trimming is not a separate task to schedule — do it in the same change, every time.
## How to work with tasks
Use the file `todo.md`.
For each todo item, interview the user extensively to deeply understand the scope and goal of
each. When done, check the completed task in `todo.md`. Commit all changes and push to a new
branch, create a PR and merge it when the CI/CD turns green.
## Project priorities (do not erode)
1. **Simplicity** — prefer the solution that is easiest to understand, smallest, and most readable.
2. **Few dependencies** — runtime deps stay minimal (today `ejs`, `lucide-static`, `@larvit/log`).
Prefer the Node standard library; justify any new dependency; do not add frameworks. The app is
**stateless — no database**. Auth/identity/OAuth are **Ory sidecar services** reached over their
REST APIs with built-in `fetch` — no SDK. New capabilities ship as **plugin folders** under
`plugins/` that fetch their data from upstream services, not as core code.
3. **Strict TypeScript**`tsconfig.json` is strict (incl. `noUncheckedIndexedAccess`,
`exactOptionalPropertyTypes`, `verbatimModuleSyntax`). Keep it that way. Prefer exact types;
limit nullable and multi-option types.
4. **Environment-agnostic** — no `NODE_ENV` branching. Every behaviour is an **explicit config
toggle** read once in `src/config.ts`; compose files set them per deployment.
5. **Semantic, accessible DOM** — the right element for the job (landmarks, one `<h1>` per page +
sane heading order, lists, `<table>` with row/column headers, `<fieldset>`/`<legend>`, `<button>`
vs `<a>`); ARIA only to fill real gaps. Classes/ids name *meaning*, not looks.
6. **Full, parallel E2E** — every user-facing flow has a Playwright test, shipped in the same change
as the surface. Tests stay independent and side-effect-free so the suite runs `fullyParallel`.
7. **Powerful, fail-loud plugins** — the plugin API is the product's main surface and the only way to
add domain features. It optimises for being powerful, predictable and overloadable, and the host
**fails loud at boot/discovery** rather than sandboxing at runtime. Runtime crash-isolation is a
deliberate **non-goal**.
## Deliberate architectural deviations (don't re-flag)
Intentional, reasoned choices — an architecture review should honor them, not re-raise them.
Revisit only if the stated reason stops holding.
### Structure & contracts
- **`src/` is grouped by concern**, not flat — `http/`, `auth/`, `i18n/`, `plugin-host/`, `ui/`,
with `server.ts`/`config.ts`/`logger.ts` and the topology-guard `*.test.ts` at the root; tests are
co-located. Add a new module to the folder owning its concern. The core ships **no domain
screens** — even the admin GUI is a drop-in plugin (`examples/plugins/admin/`).
- **Plugins and config import the host only through a barrel** — `@plainpages/plugin-api`
`plugin-api/index.ts``src/plugin-host/plugin-api.ts`, `#menu-config``src/ui/menu-config.ts`,
never a relative `../../src/*` path. These two barrels are the whole contract surface; don't "fix"
either back to a relative path. Three consequences:
- `@plainpages/plugin-api` re-exports the Ory client types (`KratosAdmin`/`KetoClient`/`HydraAdmin` + their
DTOs and error classes), so those shapes are **contract-visible** — changing them needs a major
`apiVersion` bump, not a free refactor.
- **The barrel is a package, not a `#`-import, so a plugin folder may carry its own
`package.json`** and depend on npm packages (README → Plugin dependencies). The Dockerfile links
it into `/node_modules`, above every plugin scope. Never let a copy reach a plugin's own
`node_modules`: two instances of the barrel break `instanceof` across the boundary, which
`plugin-api.test.ts` guards by asserting both paths reach one module.
- **`config/` is still a plain dir — no `package.json` of its own**, or `#menu-config` resolves
against that instead and boot fails loud. An operator's menu override has no use for
dependencies; if that changes, it needs the same package treatment.
- **`examples/` mirrors the drop-in mount dirs** — `examples/plugins/<id>/` copies to
`plugins/<id>/`, `examples/config/menu.ts` to `config/menu.ts`. Both mirrors are in
`tsconfig.include` and resolve the host through the barrels, so each typechecks in place *and*
copies across unchanged. Never commit real plugins/config into the root mount dirs — they ship empty.
- **`ctx.chrome` is lazily memoized — do not make it unconditional** or move it into the base request
context. It protects the I/O-free hot path on the public, bot-hit landing (`/`).
- **A plugin-owned render always runs on that plugin's context.** The landing slots (`home`,
`dashboard`) and an `onRequest` short-circuit build their context with `contextFor(pluginId)`
exactly as a plugin route does — otherwise `ctx.t` is the core translator and the plugin's own keys
render as bare keys on the pages it owns.
- **Email is delegated to Kratos** (it renders + sends recovery/verification mail); `web` never
touches SMTP. Customization is Kratos' `courier.template_override_path`, not app code.
### Authorization
- **Vocabulary: `User``Group``Permission`, and there is no `Role`.** Keto ships no namespaces —
all four in `ory/keto/namespaces.keto.ts` are ours. A permission is one operation ("read shifts");
a role is a *bundle*, which here is just a group with several grants (groups nest). Ory's own
"permission" (the `Resource` `permits`: view/edit/delete) is the separate per-row tier.
- **A permission name is always `<resource>:<action>`** — `scheduling:read`, `users:write`. A bare
word names *who someone is* (a role), and roles are groups here. **Enforced at discovery**
(`isValidPermissionName` in `plugin-host/plugin.ts`, checked by `shapeError` over every route/nav
`permission` and every declared name), fail-loud like any other manifest rule — not only in the
admin GUI, which an operator removes by not copying it in.
- **Names are authored in plugin code; only grants live in Keto.** The host collects every installed
plugin's declarations into one catalog (`declaredPermissions``ctx.declaredPermissions`), and
that catalog *is* the list the admin screens offer. Hence **no Permissions admin screen**: nothing
in a GUI invents a name, and holding one is a property of a user or group, edited as a checkbox
list there. A Keto tuple naming something no installed plugin declares gates nothing, is not
offered, and is never revoked by an unrelated save — the picker only speaks for what it showed.
- `<resource>` is **global, not plugin-scoped** (hence `oauth2-clients`, not `clients`): users are
the *host's*, and cross-plugin sharing is a goal. Cost: collision-freedom is a convention rather
than structural. Accepted — the alternative penalizes the sharing case.
- **Declaring a permission stays optional.** Mandatory declaration would let `findConflicts` see all
overlaps, but would then warn on exactly that legitimate sharing case. Shape is enforced;
declaration is not.
- `ADMIN_PERMISSIONS` **defaults to empty**, and **an unusable value is dropped with a warning,
never fatal** — fail-loud belongs at the manifest boundary where a developer authored the
mistake, whereas `bootstrap` gates `web`, so refusing operator env takes the whole stack down
(`e2e-tests/compose.auth.yml` seeds a bad value to prove the container survives one). The seed is
a function of what `bootstrap` discovers, so a plugin dropped in after first boot needs
`docker compose up -d`, not `restart web`. `bootstrap`'s matching `./plugins` mount belongs in
`compose.override.yml` and nowhere else: in the base file it would desynchronise prod and collide
with the e2e stacks, which bind individual plugins *inside* `/app/plugins` (a nested mount into a
read-only parent is EROFS and the container never starts). Valid while bootstrap is the only
writer of grants.
- **`actionForMethod` is plugin-local and must not migrate into `@plainpages/plugin-api`.** Inside the admin
example it keeps the route table and the in-handler guard deriving from one function, so 29 routes
× 2 gate sites cannot drift. Generalised, it would make authorization a function of the transport
verb — a route table must answer "what does this need?" on its own.
- **A `:read`-only holder must never be shown a write affordance.** The list/detail models carry
`canWrite` and the views drop create/save/delete/add/remove; the permission picker still renders,
disabled, because *seeing* who holds what is the point of `:read`. A **write-intent GET** (a create
form, a delete-confirm page) is the exception to `actionForMethod` and gates on `:write`. Two
grant-specific guards go with it: you cannot revoke your own **direct** grants (self-lockout would
need a `curl` against Keto to undo), and a permission held *through a group* renders
ticked-but-disabled, because unticked stated the opposite of the truth. **Known gap:** the group
paths are unguarded — unticking a permission on a group you belong to, leaving it, or deleting it
can still strip your own access. The robust "last effective holder" check needs a reverse Keto
query and is deferred.
- **`users:write` and `groups:write` are equivalent to full administrative access**: `groups:write`
adds you to any group, including one holding every permission; `users:write` mints a recovery code
for any account. The containment the split buys is real on the **read** half only (`users:read` is
a safe helpdesk grant). Don't let the per-resource naming imply otherwise in docs.
- **Plainpages says "user" everywhere; Ory's word is "identity".** House style, not a renamed
concept. The single exception is the `Identity` DTO in `src/auth/kratos-admin.ts`, which mirrors
Kratos' wire shape — don't rename it.
### i18n
- **The locale lives in the URL, never in a cookie.** `?locale=sv-SE``Accept-Language``en-US`,
and when the URL asked for one the host carries it onto the links it renders. A cookie would make a
page's language invisible in its address and unshareable; the cost is that a plugin wraps its own
hrefs. Matching is exact on a full tag (`sv-FI``sv-SE`), except that a lone language from
`Accept-Language` takes the first regional catalog for it.
- **The core building blocks carry the locale; a plugin doesn't have to.** The shell, `pagination`,
`filter-bar`, `data-table`, `auth-card`, `flow-body`, `field` and `menu` wrap every href in
`localeHref`; nav and sign-in are wrapped in `chrome.ts`; the two GET forms carry it as a hidden
`locale` input, since a GET submit replaces the whole query string. **A form's `action` counts as a
link** — sign-out, consent and auth-card forms carry it too, or picking a language and then saving
anything drops back to `Accept-Language`. The obligation stays on the building block, never on each
call site. `ctx.localeHref` remains for hrefs a plugin's own markup emits. The one round-trip that
cannot carry it is the Kratos sign-in POST (absolute off-site URL).
- **`locale` is a host-owned query param** — in `parseListQuery`'s reserved set, so a localized list
page doesn't hand a plugin a phantom `locale` filter. The i18n view locals (`t`, `locale`, `locales`,
`localeHref`, `localeParam`, `localeSwitch`, `dir`) are likewise reserved, merged after a handler's
`data` so a collision loses the key instead of breaking the shell.
- **Catalogs are checked at boot, not at render.** Every locale is compared against its set's `en-US`
— keys, string-vs-plural kind, and the plural categories `Intl.PluralRules` requires — and a
mismatch stops startup. A plugin may ship fewer locales than the host (its strings fall back to
`en-US` per key), never one the host lacks.
- **`locales/` at the repo root is a drop-in mount**, like `plugins/` and `config/``locales/<tag>.ts`
for the core, `locales/plugins/<id>/<tag>.ts` for a plugin; a new tag adds a language, an existing
one replaces that catalog wholesale. Adding a language must never require forking the image. The
SHIPPED `en-US` stays the parity baseline even when the mount replaces it, so a mounted catalog is
checked rather than trusted (one compared only against itself would boot green with the whole UI
rendering keys).
- **The language picker is on every page, POST-rendered ones included.** A POST-rendered URL often
answers no GET (`POST /admin/users/:id/recovery`), so the host resolves the picker's target
(`app.ts``switchBase`): this path when it answers GET, else the same-origin Referer, else `/`.
Accepted cost: switching language there leaves that POST's own result behind. Valid while the picker
is expected on literally every page — if that softens, hiding it after a POST is simpler.
- **An unknown translation key renders as itself.** That single rule lets a nav label, branding, or a
menu `rename` be either a key or plain text without a second field or a migration. Don't "fix" it
into a loud failure: a manifest with plain labels must keep working.
- **`t()` returns raw text; the view escapes it.** Messages go through `<%= %>` like any other value;
one carrying markup uses `<%- %>`, and then its `{{vars}}` are escaped at the call site. Don't move
escaping into `t()` — every other value in a view would become the odd one out.
- **RTL is out of scope until there is a real use case.** `textDirection` sets `<html dir>` because
that is free and correct, but the stylesheet keeps physical `left`/`right` properties; a genuine RTL
locale needs those moved to logical ones first. Valid while no deployment needs an RTL language.
### UI
- **A dropdown is a `<button popovertarget>` + `[popover]`, never a `<details>`.** The browser then
owns open/close — the only zero-JS way to dismiss by clicking outside — and the panel sits in the
top layer, so a row kebab is not clipped by `.table-wrap`'s `overflow`. Four rules hold it
together: the panel carries **`position-anchor: auto`** (a bare `anchor()` resolves to nothing in
all three engines); it stays the trigger's **next sibling inside the `.menu` wrapper**, which the
open-state style and the old-browser fallback both read; the partial **requires a caller-named
`id`** and fails loud without one, since that is the `popovertarget` idref (never generate one —
nondeterministic HTML forecloses the caching decision); and **neither `aria-expanded` nor
`aria-haspopup` is written**, because a zero-JS invoker cannot keep the first truthful and the
second would promise `role="menu"` semantics these panels don't implement. `<details>` stays where
it means disclosure rather than popup: the nav tree. `shell.ejs` hand-rolls the same block for the
profile menu (its trigger composes escaped user values and its one item is a CSRF POST form) — keep
the two in step.
- **`ICON_NAMES` (`src/ui/icons.ts`) is a host-owned registry, not a frozen plugin contract**, so it
is deliberately not re-exported from `@plainpages/plugin-api`. The palette may narrow when the last reference
to an id goes, and a plugin needing one gets it re-registered in the same change. Accepted cost: an
unknown sprite id renders blank instead of failing loud (the `every icon <use> resolves` e2e test
catches anything reaching the nav).
### Build, test & release
- **Deps install to `/node_modules`, above `WORKDIR /app`** — Node resolves upward, so dev's `.:/app`
bind mount has nothing to shadow. Not a volume at `/app/node_modules`: the daemon creates a mount
destination as root whatever `--user` says, leaving a root-owned dir in the checkout. Nothing may
sit at that path now — it shadows `/node_modules` silently (`src/compose.test.ts` guards the compose
files, `.dockerignore` the image).
- **A container whose output a human then edits or deletes runs as `--user "$(id -u):$(id -g)"`** —
the E2E runner (artifacts) and a lockfile edit, or the output is root-owned and needs `sudo`, which
a dev box may not have. Not universal: `bootstrap` writes `jwks.json` as root when it is absent on
first boot; the committed dev key makes that rare, and when it happens the rotation runbook's
host-side `>` needs the file re-owned first (valid while the dev key ships committed). Three
consequences: `e2e-tests/artifacts/` is *tracked* (`.gitkeep`), since an absent bind-mount source is
daemon-created as root and that uid then cannot write it (README → Upgrading); the runner image sets
`HOME=/tmp`, since an arbitrary uid has no passwd entry and would land on an unwritable `/`; and
rootless Docker wants the flag *dropped*, container root already being the invoking user. Baking a
`USER` in instead does not work — the image's `pwuser` is 1001 and no fixed uid matches every host.
`src/compose.test.ts` guards every documented command, `src/ci-gate.test.ts` the gate's own.
- **Anything the browser logs fails the E2E test that provoked it.** Every spec takes its `test` from
`e2e-tests/console-guard.ts`, which fails a test on a console error/warning or uncaught exception on
any page it opened. A zero-JS app has nothing to say in the console, so the bar is *zero* rather than
a curated tolerance list; the two exceptions are narrow — a module-level allowance for the COOP header
Chromium drops (the e2e stacks serve plain http over container hostnames), and `allowConsole(re)` for
a test whose own page provokes a message on purpose. `src/e2e-console-guard.test.ts` locks the wiring
in the *unit* gate, since a spec importing `test` straight from Playwright — or minting a page with
a raw `newPage()` instead of `watchedPage()` — would run unwatched and green. Accepted cost: a page
outliving its test can log late and fail the next one.
- **The Ory-free specs run in all three engines; the Ory-backed ones stay on Chromium.**
`visual.spec.ts` + `language.spec.ts` are side-effect-free, so parallel runs don't collide, and a
console message only appears in the engine that renders the page (`ORY_FREE` in
`e2e-tests/playwright.config.ts`). The rest write users, groups and sessions to one shared backend,
so widening them means a stack per engine.
- **The docs-only CI skip is `*.md` anywhere in the tree, not just the root** — no test, build step or
workflow reads a markdown file. Both git channels in `ci.sh`'s `docs_only()` pass `--no-renames`:
rename detection names only the destination, so `git mv src/app.ts notes.md` would otherwise read as
docs and skip the gate over a source file that was gone. `src/ci-gate.test.ts` locks the flags as a
*text* guard — the test image ships neither `git` nor `bash`. Revisit if a `.md` ever becomes
load-bearing.
- **CI docker logins share the runner host's Docker config.** The act_runner is host-mode, so
`docker login`/`logout` in the workflows mutate one shared `~/.docker/config.json`: concurrent jobs
can race (one job's logout can 401 another's push — recover by re-running), and tokens sit in that
file between login and logout. Same class: concurrent runs share the workspace dir, so ci.sh's
web-image build races another run's container creation on the `<project>-web` tag. Accepted for a
single-maintainer cadence; serialize with a workflow `concurrency` group if it ever bites.
- **Plainpages is pre-announcement: no tags, no releases.** `auto-release` is gated behind the
`AUTO_RELEASE` Actions variable (unset ⇒ skipped, the fail-safe direction on every unknown-`vars`
path) — a version only communicates to consumers and there are none. Two couplings:
`registry-cleanup` keeps a hash image only while its commit is a branch head *or* release-tagged, so
with zero tags a hand-cut tag must sit on `main`'s tip; and `mirror.yml` pushes tags with `--prune`
(its `fetch-tags: true` is load-bearing), so a tag or Release created on GitHub is swept away and
releases are cut on Gitea only. Valid until the maintainer says Plainpages is ready to show people.
- **A stricter manifest rule breaks already-copied plugins**, and while `HOST_API_VERSION` is frozen
the failure names a symptom rather than the cause — `checkApiVersion` would refuse a stale plugin by
*version*, but only once the freeze lifts. Until then a stricter rule ships with a README →
Upgrading entry and a re-copy hint in the discovery error. Fail-loud stays right either way: the
alternative is a route gating on a name nobody can be granted, i.e. a permanent silent 403.
**Valid while `HOST_API_VERSION` stays frozen.**
## Docker only — no host tooling
**Everything** (install, typecheck, test, run, build, deploy) goes through Docker /
Docker Compose. **Never run `node`, `npm`, or `tsc` on the host.**
```bash
docker compose up # dev server, live reload
docker compose run --rm --no-deps web npm run typecheck # strict type check (--no-deps: skip Ory)
docker compose run --rm --no-deps web npm test # tests
docker compose -f compose.yml up --build -d # production
```
## README structure (keep it this way)
`README.md` serves two readers, in this order — preserve it when editing:
1. **First-time reader (top).** A one/two-sentence tagline, then a **Quick start** that gets the
stack up and a *minimal* plugin live. Nothing comes before Quick start. Keep its commands
copy-pasteable; deeper detail lives in its own section, linked.
2. **Returning developer (rest).** A **Contents** ToC right after Quick start, then sections ordered
by **what an adopter reaches for first**, not by architectural layering: Overview → Users, groups
& permissions → Building plugins → menu/blocks/interactivity → Configuration → Auth → Email →
Architecture → Testing → Production → Observability → JWT-rotation runbook → Project-layout file
map → Extending. Place a new section by how early an adopter needs it. **Users, groups &
permissions precedes Building plugins** because a manifest's `permission:` gate is unreadable
without the model, and it is the one home for that model.
Keep the ToC in sync when you add/rename/remove an `H2`/`H3`. **Don't document internals** — how a
script reaches a decision, what a function guards; a developer reads that off the code in seconds.
The README earns its length on how to use and operate Plainpages, the external contracts, and
one-time setup. A file-map or table row gets a clause, not a paragraph.
## Rules
- Node 24 runs `.ts` directly (type stripping). Keep all TypeScript **erasable**
(`erasableSyntaxOnly` is on): no `enum`, `namespace`, parameter properties, or decorators. Import
local modules with their `.ts` extension.
- **No `.mjs`.** Write modules as `.ts` — even standalone scripts run in bare `node:24` containers.
If a file genuinely must be plain JavaScript, use `.js`; `"type": "module"` is set in both
`package.json`s, so `.js` is ESM.
- **No build step** and no compiled artifacts — do not add a bundler or `tsc` emit.
- Before finishing a change, run the typecheck and tests above; both must pass.
- Tests use the built-in `node --test` runner — no test framework dependency.
- English everywhere.
- Pin all dependencies and Docker images to exact, human-readable **semantic versions** — never
ranges (`^`, `~`) and never digests. npm deps via `.npmrc` (`save-exact=true`) + `npm ci`; images
by tag.
- **`HOST_API_VERSION` is frozen at 1.0.0 until the first external install**, even for additive
contract changes. With no third-party plugin in the wild a bump can only produce noise. The
promotion trigger is the first external plugin — from then on follow the versioning table in
README → Contract versioning. **The frozen surface includes `views/partials/*.ejs`**: the view
resolver makes every core partial an `include()` root for a plugin's views, so their option names
and emitted markup are author-visible. Know the hole that leaves — discovery fails loud on a bad
`apiVersion`, but `include("menu", { open: true })` silently ignores a dropped option. Promotion
must cover the partial vocabulary too.
- A plugin's `apiVersion` is a **hand-written literal** semver — the host version it was built
against — bumped by hand on rebuild, **never** the host's `HOST_API_VERSION` constant. Importing
the constant makes every plugin always equal the host, so `checkApiVersion` can never fire.
- **Plugin route handlers are thin and per-route, keyed on `ctx.params`.** Register one handler per
`{method, path}` in the manifest (the host extracts `:id`/`:name` and 404s malformed `%`-encoding).
Don't funnel many routes into one dispatcher that re-parses `ctx.url.pathname`: it duplicates the
URL shape, ignores the router's params, and has to re-handle HEAD. Factor shared per-request setup
into a small `withX` wrapper — see `examples/plugins/admin/`.
- **`handleRequest` (`src/http/app.ts`) is a known complexity hotspot** — ~160 lines tracking
canonical host, static, locale, session + re-mint, CSRF, chrome, hooks, plugin routing, builtin
routing, 405/404 and error mapping. The pure parts are already extracted and separately tested;
what remains is orchestration. Planned split along those seams; don't grow it further without
taking one out.
- Reviews are maintainer-triggered (e.g. via the larv-review skill) — never auto-run reviewer agents.
- **A user-visible string belongs in a catalog, not in the code or a view.** Core strings go in
`src/i18n/locales/en-US.ts` (then every other locale, or the boot fails); a plugin's go in its own
`i18n/`. Operator/developer-facing text — boot errors, log messages, guard messages — stays English.
A pure view-model builder takes an optional `t` defaulting to its own English, so a unit test reads
in words; handlers pass `ctx.t`.
- **One verb per action in the English UI: sign in, sign out, create account.** Not "log in", "log
out" or "sign up", inflections included — a second spelling for one button reads as a second thing;
the noun ("a sign-in error") is unaffected. A plugin's catalog and every other locale follow the
same rule in their own language. An unmapped Kratos id renders Kratos' own wording — map the id when
it matters. **Held by the author, never by a test:** slightly different wording is often the right
call, and a build-failing check takes that judgment away.
- Use well formed, standard compliant, rich URIs. Prefer state in the URL over POSTing it, for
example on list pages with filters and pagination. Do `ids=x&ids=y`, not `ids[]=x&ids[]=y` and not
`ids=x,y`.
## Comments
Default to **no comment**. Delete one that restates the adjacent code, repeats a convention used
elsewhere, justifies self-evident code, or records history. Write one only for what a competent
reader of *this* codebase could not infer: a surprising why, a footgun, an invariant, an external
constraint. See [Prose discipline](#prose-discipline).