# Design: `@suaveplan/readline` + `@suaveplan/cli`

**Date:** 2026-04-20
**Branch:** genesis
**Status:** Approved — ready for implementation planning

---

## 1. Problem

The `@suaveplan/cli` package needs to land on genesis at enterprise quality. Its `prompt` module currently depends on `node:readline`, which ties the package to the Node runtime and blocks the "universal" guarantee. No standalone readline primitive exists in the monorepo.

---

## 2. Solution

Introduce `@suaveplan/readline` as a new `universal/platform` package, then port `@suaveplan/cli` as a full enterprise rewrite that depends on it. Both land in dependency order within the same session.

---

## 3. Package Locations

| Package | Path | FOLDERS.yml domain |
|---|---|---|
| `@suaveplan/readline` | `universal/platform/readline` | `platform` |
| `@suaveplan/cli` | `universal/platform/cli` | `platform` |

`FOLDERS.yml` gains `readline` in the `universal/platform` list. `cli` already appears there — only `readline` is added, bringing the total to 7 entries:

```yaml
platform: [ cli, electrobun, macos-contacts, opentelemetry,
            profiler, readline, sitemap ]   # 7
```

---

## 4. Dependency Chain

```text
@opentelemetry/api  zod  tslib
         ↓
@suaveplan/error  @suaveplan/types
         ↓
@suaveplan/readline
         ↓
@suaveplan/cli
```

---

## 5. `@suaveplan/readline`

### 5.1 Architecture

Three feature modules share one internal byte scanner:

```text
src/
  scanner/      ← internal byte engine (not exported)
  reader/       ← public: readLines() AsyncGenerator API
  interface/    ← public: createInterface() interactive prompt API
  errors/       ← public: ReadlineError + stable code registry
```

`"sideEffects": false` must be set in `package.json`.

No root `"."` barrel export. Consumers import directly from subpaths to enable tree-shaking.

### 5.2 `scanner` (internal)

Ports the [maleck13/readline](https://github.com/maleck13/readline) byte scanner from JavaScript to TypeScript. Replaces `EventEmitter` with an internal bounded async push queue (backpressure-safe). Handles LF, CR, and CRLF line endings. Not exported via `package.json` subpaths.

```ts
interface ScannerOptions {
  maxLineLength?: number;  // default 4096
  encoding?: BufferEncoding;
}
function createScanner(input: Readable, opts?: ScannerOptions): AsyncGenerator<string>
```

### 5.3 `reader` — `@suaveplan/readline/reader`

```ts
interface ReadLinesOptions {
  maxLineLength?: number;
  encoding?: BufferEncoding;
  skipEmpty?: boolean;
  signal?: AbortSignal;
}

async function* readLines(
  input: Readable | ReadableStream | string,
  options?: ReadLinesOptions
): AsyncGenerator<string, void, unknown>
```

Accepts a Node `Readable`, a WHATWG `ReadableStream`, or a file path string. Honours `AbortSignal` at each yield point.

### 5.4 `interface` — `@suaveplan/readline/interface`

```ts
interface ReadlineOptions {
  input: Readable;
  output?: Writable;
  signal?: AbortSignal;
}

interface ReadlineInterface {
  question(prompt: string, signal?: AbortSignal): Promise<string>;
  close(): void;
  readonly closed: boolean;
  [Symbol.asyncIterator](): AsyncIterator<string>;
}

function createInterface(options: ReadlineOptions): ReadlineInterface
```

The async iterator inherits the `AbortSignal` from `ReadlineOptions`. `ReadlineInterface` satisfies `@suaveplan/cli`'s existing `InputReader` type (`{ question, close }`) by structural typing — no adapter required.

`createInterface()` emits an OTel span covering the interface lifetime (start on creation, end on `close()`, error status on abort).

### 5.5 Error codes

```text
READLINE.SCANNER.LINE_TOO_LONG
READLINE.SCANNER.STREAM_ERROR
READLINE.INTERFACE.CLOSED
READLINE.INTERFACE.ABORTED
READLINE.READER.STREAM_ERROR
```

### 5.6 Subpath exports

```json
{
  "./reader/reader":       { "import": { "types": "...", "default": "..." } },
  "./interface/interface": { "import": { "types": "...", "default": "..." } },
  "./errors/errors":       { "import": { "types": "...", "default": "..." } }
}
```

`scanner` is internal — no subpath export.

### 5.7 Key `package.json` fields

```json
{
  "sideEffects": false,
  "dependencies": {
    "@suaveplan/error": "workspace:^",
    "@suaveplan/types": "workspace:^",
    "@opentelemetry/api": "catalog:observability",
    "zod": "catalog:forms",
    "tslib": "catalog:build"
  },
  "devDependencies": {
    "@suaveplan/testing": "workspace:^",
    "@vitest/coverage-istanbul": "catalog:testing",
    "fast-check": "catalog:testing",
    "mitata": "catalog:testing",
    "vitest": "catalog:testing"
  }
}
```

---

## 6. `@suaveplan/cli`

### 6.1 Architecture

Full enterprise rewrite of `suaveplan/packages/universal/cli`. Preserves the complete public API surface. Adds structured errors, Zod schemas, OTel instrumentation, AbortSignal support, and replaces `node:readline` with `@suaveplan/readline/interface`.

```text
src/
  app/       command/   parser/    style/
  errors/    output/    spinner/   progress/   prompt/
```

`"sideEffects": false` must be set in `package.json`.

### 6.2 `errors`

```ts
class CliError extends SuaveplanError { ... }
```

Stable codes:

```text
CLI.PARSE.UNKNOWN_OPTION
CLI.PARSE.MISSING_VALUE
CLI.PARSE.INVALID_VALUE
CLI.PARSE.MISSING_ARGUMENT
CLI.PARSE.MISSING_REQUIRED_OPTION
CLI.COMMAND.NO_ACTION
CLI.COMMAND.UNKNOWN_SUBCOMMAND
CLI.APP.RUN_FAILED
CLI.APP.ABORTED
```

### 6.3 `parser`

Preserved API. Throws `CliError` (CLI.PARSE.*) instead of bare `Error`. Adds `ParserConfigSchema` and `ParsedArgsSchema` Zod exports.

```ts
function parseArgs(argv: string[], config?: ParserConfig): ParsedArgs
function parseOptionFlags(flags, description?, defaultValue?): { name, config }
function parseArgumentSpec(spec, description?): ArgumentConfig
```

### 6.4 `command`

Preserved fluent API. `execute()` gains an OTel span. Throws `CliError` on missing action and unknown subcommand.

```ts
class Command {
  description / option / argument / action / command / alias / hidden / example
  execute(argv: string[], parentName?: string): Promise<void>
  helpText(parentName?: string): string
  getParserConfig(): ParserConfig
}
```

### 6.5 `app`

Preserved API. `run()` gains an OTel span and an optional `AbortSignal`. Throws `CliError(CLI.APP.ABORTED)` when the signal fires.

```ts
class App {
  run(argv?: string[], options?: { signal?: AbortSignal }): Promise<void>
  helpText(): string
  description / option / argument / command / action / example
}
function cli(name: string, version?: string): App
```

Zod export: `AppConfigSchema`.

### 6.6 `style`, `output/format`, `output/table`

API unchanged. Zod schemas added for option types. Bare `Error` throws replaced with `CliError`.

`output/format` and `output/table` follow the standard five-file co-located layout:

```text
src/output/
  format/
    format.ts  format.types.ts  format.test.ts  format.md  index.ts
  table/
    table.ts   table.types.ts   table.test.ts   table.md   index.ts
```

### 6.7 `spinner` + `progress`

`AbortSignal` added to options. Stream remains injectable (`WritableStreamLike`).

```ts
interface SpinnerOptions  { text?, frames?, interval?, stream?, signal?: AbortSignal }
interface ProgressOptions { total, width?, stream?, signal?: AbortSignal }
```

### 6.8 `prompt`

`createDefaultReader()` uses `createInterface()` from `@suaveplan/readline/interface`. All five prompt functions (`text`, `password`, `confirm`, `select`, `multiselect`) gain an optional `signal?: AbortSignal`. `node:readline` is absent from the dependency graph.

### 6.9 Subpath exports

```json
{
  ".":                          "barrel",
  "./app/app":                  "...",
  "./command/command":          "...",
  "./parser/parser":            "...",
  "./style/style":              "...",
  "./output/format/format":     "...",
  "./output/table/table":       "...",
  "./spinner/spinner":          "...",
  "./progress/progress":        "...",
  "./prompt/prompt":            "...",
  "./errors/errors":            "..."
}
```

### 6.10 Key `package.json` fields

```json
{
  "sideEffects": false,
  "dependencies": {
    "@suaveplan/readline": "workspace:^",
    "@suaveplan/error": "workspace:^",
    "@suaveplan/types": "workspace:^",
    "@opentelemetry/api": "catalog:observability",
    "zod": "catalog:forms",
    "tslib": "catalog:build"
  },
  "devDependencies": {
    "@suaveplan/testing": "workspace:^",
    "@vitest/coverage-istanbul": "catalog:testing",
    "fast-check": "catalog:testing",
    "mitata": "catalog:testing",
    "vitest": "catalog:testing"
  }
}
```

---

## 7. Testing Strategy

### Unit tests (co-located `.test.ts`)

| Module | Key scenarios |
|---|---|
| `scanner` | LF / CR / CRLF, max-line overflow, empty input, mid-stream abort |
| `reader` | file path, WHATWG `ReadableStream`, `AbortSignal` mid-iteration |
| `interface` | real `Readable`/`Writable` pair, question/close lifecycle, `closed` guard, async iterator abort via inherited signal, OTel span created / ended on close / error status on abort |
| `parser` | all option types, `--no-*`, `--`, variadic, unknown options |
| `command` | subcommand routing, aliases, help text, error paths |
| `spinner` / `progress` | injectable stream (no TTY), AbortSignal cancellation |
| `prompt` | injected mock `InputReader`, validation retries, all five prompt types |

### Property-based tests (fast-check)

- **scanner/parser round-trip** — split any string into lines, scan bytes, reassemble → original string
- **parser safety** — `parseArgs(argv, { allowUnknown: true })` never throws for any `argv`
- **style round-trip** — `stripAnsi(style.bold.red(s)) === s` for all strings `s`
- **table invariant** — column widths always ≥ max cell content width

### Coverage gate

100% statement + branch + function + line (istanbul) for both packages.

---

## 8. Benchmarks

### `@suaveplan/readline` (`src/__benchmarks__/`)

| Benchmark | Description |
|---|---|
| `scanner-throughput` | 1 MB and 10 MB streams, lines/sec |
| `reader-file` | `readLines()` over a temp file vs `node:readline` baseline |

### `@suaveplan/cli` (`src/__benchmarks__/`)

| Benchmark | Description |
|---|---|
| `parser-throughput` | 10 000 `parseArgs()` calls with a 20-flag config |
| `app-run` | Full `App.run()` dispatch cycle |

Baselines published in each package's `README.md`. A >10% regression fails CI. Each package's `package.json` must include a `"bench"` script and the turbo pipeline must include a `bench` task.

---

## 9. OpenSpec Changes

```text
openspec/changes/
  enterprise-readline/
    proposal.md
    tasks.md
    specs/readline/spec.md
  enterprise-cli/
    proposal.md
    tasks.md
    specs/cli/spec.md
```

Both archive on ship to `openspec/archive/2026-04-20-enterprise-readline/` and `openspec/archive/2026-04-20-enterprise-cli/`.

---

## 10. CLAUDE.md Additions

Add two entries to the genesis package listing under `platform`:

- **readline** — terminal I/O primitive: AsyncGenerator line reader (`readLines`), interactive prompt interface (`createInterface`), byte scanner engine. Depends on `@suaveplan/error`, `@suaveplan/types`, `@opentelemetry/api`, `zod`.
- **cli** — CLI toolkit: argument parser, command router, ANSI styling, output formatting, table renderer, spinner, progress bar, interactive prompts. Depends on `@suaveplan/readline`, `@suaveplan/error`, `@suaveplan/types`, `@opentelemetry/api`, `zod`.

---

## 11. Acceptance Criteria

Both packages are enterprise-done when:

- [ ] `bunx turbo lint typecheck test --filter=@suaveplan/readline` green
- [ ] `bunx turbo lint typecheck test --filter=@suaveplan/cli` green
- [ ] 100% istanbul coverage on both packages
- [ ] Zero `any`, `TODO`, `FIXME`, `ts-ignore`, `.skip` in `src/`
- [ ] Every `.ts` implementation file has a sibling `.md` (≥200 words)
- [ ] Zod schemas exported for all public types
- [ ] OTel spans on `App.run()`, `Command.execute()`, `createInterface()`
- [ ] AbortSignal honoured in `readLines()`, `question()`, async iterator, `spinner`, `progress`, all prompt functions
- [ ] `node:readline` absent from `@suaveplan/cli` dependency graph
- [ ] `"sideEffects": false` in both `package.json` files
- [ ] mitata benchmarks in `src/__benchmarks__/` with `"bench"` script wired in `package.json` and turbo pipeline
- [ ] Baselines published in both `README.md` files
- [ ] OpenSpec changes archived; `FOLDERS.yml` and `CLAUDE.md` updated