feat: add kitchen view command and parser skeleton (task 0003)

Cut the first vertical slice through both layers: a runnable
`kitchen view <file>` that reads a Recipe File, parses it, and renders
it styled to the terminal.

@kitchen-md/core exposes a pure, total `parse(input): DocumentAST` built
on a minimal remark pipeline (parse + frontmatter) with a translation
layer to core's own AST types — frontmatter passthrough, HeadingBlock,
ParagraphBlock, and TextNode. remark types never leak into the public
API.

@kitchen-md/bin's `view` subcommand (commander) reads the file and hands
the DocumentAST to a pure `render(ast): string` (chalk, ANSI
auto-suppressed off a TTY). Fallible file I/O is modelled as a neverthrow
Result over a tagged-union CliError, matched at the boundary: stdout on
success, stderr and exit 1 on failure. The command functions sit beside
the import.meta.main-guarded CLI entry so they are testable in-process.

Tests follow ADR 0009's tiers — unit (parse, render), integration (the
view command's Result), and e2e (the binary as a subprocess) — with
coverage, a path-scoped test-report generator, and a prose fixture
rounding out the tooling. ADR 0008 records errors-as-values at the CLI
boundary; ADR 0009 records the testing tiers.

packages/bin/package.json

@@ -11,6 +11,10 @@
     "build": "bun build --compile ./src/index.ts --outfile kitchen"
   },
   "dependencies": {
-    "@kitchen-md/core": "workspace:*"
+    "@kitchen-md/core": "workspace:*",
+    "chalk": "^5.6.2",
+    "commander": "^15.0.0",
+    "neverthrow": "^8.2.0",
+    "yaml": "^2.9.0"
   }
 }

packages/bin/src/end_to_end_test.ts

@@ -0,0 +1,65 @@
+import { describe, expect, test } from "bun:test";
+import { join } from "node:path";
+
+const repoRoot = join(import.meta.dir, "..", "..", "..");
+const entry = join(repoRoot, "packages", "bin", "src", "index.ts");
+
+async function runKitchen(args: string[]) {
+  const proc = Bun.spawn(["bun", entry, ...args], {
+    cwd: repoRoot,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+  const [stdout, stderr] = await Promise.all([
+    new Response(proc.stdout).text(),
+    new Response(proc.stderr).text(),
+  ]);
+  const exitCode = await proc.exited;
+  return { exitCode, stdout, stderr };
+}
+
+describe("kitchen CLI (e2e)", () => {
+  test("view renders a recipe file to stdout and exits 0", async () => {
+    const { exitCode, stdout, stderr } = await runKitchen(["view", "fixtures/prose.md"]);
+    const out = Bun.stripANSI(stdout);
+    expect(exitCode).toBe(0);
+    expect(stderr).toBe("");
+    expect(out).toContain("Buttered Toast");
+    expect(out).toContain("Method");
+    expect(out).toContain("Serving");
+    expect(out).toContain("Cut into triangles and serve at once.");
+  });
+
+  test("view preserves document order in the output", async () => {
+    const { stdout } = await runKitchen(["view", "fixtures/prose.md"]);
+    const out = Bun.stripANSI(stdout);
+    expect(out.indexOf("Method")).toBeLessThan(out.indexOf("Serving"));
+  });
+
+  test("ANSI styling is suppressed when stdout is not a TTY (piped)", async () => {
+    const { stdout } = await runKitchen(["view", "fixtures/prose.md"]);
+    expect(stdout).not.toContain("\x1b");
+  });
+
+  test("a nonexistent file prints a human-readable error to stderr and exits 1", async () => {
+    const { exitCode, stdout, stderr } = await runKitchen(["view", "does/not/exist.md"]);
+    expect(exitCode).toBe(1);
+    expect(stdout).toBe("");
+    expect(stderr).toContain("cannot read");
+    expect(stderr).toContain("does/not/exist.md");
+    expect(stderr.startsWith("kitchen:")).toBe(true);
+  });
+
+  test("a missing file argument prints usage to stderr and exits 1", async () => {
+    const { exitCode, stderr } = await runKitchen(["view"]);
+    expect(exitCode).toBe(1);
+    expect(stderr).not.toBe("");
+    expect(stderr.toLowerCase()).toContain("missing required argument");
+  });
+
+  test("--help lists the view command and exits 0", async () => {
+    const { exitCode, stdout } = await runKitchen(["--help"]);
+    expect(exitCode).toBe(0);
+    expect(stdout).toContain("view");
+  });
+});

packages/bin/src/index.ts

@@ -1 +1,54 @@
-// CLI entry point
+#!/usr/bin/env bun
+import { readFileSync } from "node:fs";
+import { parse } from "@kitchen-md/core";
+import { Command } from "commander";
+import { err, ok, type Result } from "neverthrow";
+import { render } from "./render.ts";
+
+export type ViewError = { tag: "read-failed"; path: string; cause: string };
+
+// The union of every error a command can surface to the boundary; new fallible commands add their variants here.
+export type CliError = ViewError;
+
+export function viewFile(path: string): Result<string, ViewError> {
+  return readFile(path).map((content) => render(parse(content)));
+}
+
+export function formatError(error: CliError): string {
+  switch (error.tag) {
+    case "read-failed":
+      return `cannot read '${error.path}': ${error.cause}`;
+  }
+}
+
+// The one place a throwing API is turned into a Result; nothing above this leaks exceptions.
+function readFile(path: string): Result<string, ViewError> {
+  try {
+    return ok(readFileSync(path, "utf8"));
+  } catch (error) {
+    const cause = error instanceof Error ? error.message : String(error);
+    return err({ tag: "read-failed", path, cause });
+  }
+}
+
+const program = new Command();
+
+program.name("kitchen").description("Read and view KitchenMD Recipe Files");
+
+program
+  .command("view")
+  .description("Render a Recipe File to the terminal")
+  .argument("<file>", "path to a Recipe File")
+  .action((file: string) => {
+    viewFile(file).match(
+      (output) => process.stdout.write(output),
+      (error) => {
+        process.stderr.write(`kitchen: ${formatError(error)}\n`);
+        process.exit(1);
+      },
+    );
+  });
+
+if (import.meta.main) {
+  program.parse();
+}

packages/bin/src/index_test.ts

@@ -1,6 +1,86 @@
-import { describe, test } from "bun:test";
+import { afterEach, describe, expect, test } from "bun:test";
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { formatError, type ViewError, viewFile } from "./index.ts";
 
-describe("cli", () => {
-  test.todo("exits with non-zero code when no file argument is given");
-  test.todo("exits with non-zero code when file does not exist");
+describe("viewFile", () => {
+  let dir: string | undefined;
+
+  afterEach(() => {
+    if (dir) {
+      rmSync(dir, { recursive: true, force: true });
+      dir = undefined;
+    }
+  });
+
+  const writeRecipe = (name: string, content: string): string => {
+    dir = mkdtempSync(join(tmpdir(), "kitchen-view-"));
+    const path = join(dir, name);
+    writeFileSync(path, content);
+    return path;
+  };
+
+  test("viewFile returns ok with the rendered document for a readable file", () => {
+    const path = writeRecipe(
+      "toast.md",
+      `# Buttered Toast
+
+Toast the bread until golden.
+`,
+    );
+
+    const result = viewFile(path);
+
+    expect(result.isOk()).toBe(true);
+    const rendered = Bun.stripANSI(result._unsafeUnwrap());
+    expect(rendered).toContain("Buttered Toast");
+    expect(rendered).toContain("Toast the bread until golden.");
+  });
+
+  test("viewFile returns ok and passes frontmatter through to the rendered output", () => {
+    const path = writeRecipe(
+      "toast.md",
+      `---
+title: Buttered Toast
+servings: 2
+---
+
+# Buttered Toast
+`,
+    );
+
+    const result = viewFile(path);
+
+    expect(result.isOk()).toBe(true);
+    const rendered = Bun.stripANSI(result._unsafeUnwrap());
+    expect(rendered).toContain("title: Buttered Toast");
+    expect(rendered).toContain("servings: 2");
+  });
+
+  test("viewFile returns a read-failed error for a nonexistent path", () => {
+    dir = mkdtempSync(join(tmpdir(), "kitchen-view-"));
+    const missing = join(dir, "does-not-exist.md");
+
+    const result = viewFile(missing);
+
+    expect(result.isErr()).toBe(true);
+    const e = result._unsafeUnwrapErr();
+    expect(e.tag).toBe("read-failed");
+    expect(e.path).toBe(missing);
+    expect(typeof e.cause).toBe("string");
+    expect(e.cause.length).toBeGreaterThan(0);
+  });
+});
+
+describe("formatError", () => {
+  test("formatError renders a read-failed error as a human-readable line", () => {
+    const error: ViewError = {
+      tag: "read-failed",
+      path: "/nope/recipe.md",
+      cause: "no such file",
+    };
+
+    expect(formatError(error)).toBe("cannot read '/nope/recipe.md': no such file");
+  });
 });

packages/bin/src/integration_test.ts

@@ -1,5 +0,0 @@
-import { describe, test } from "bun:test";
-
-describe("cli — integration", () => {
-  test.todo("invokes core parser and produces output for a real fixture file");
-});

packages/bin/src/render.ts

@@ -0,0 +1,46 @@
+import type { Block, DocumentAST, Frontmatter, HeadingBlock, InlineNode } from "@kitchen-md/core";
+import chalk from "chalk";
+import { stringify as stringifyYaml } from "yaml";
+
+const SEPARATOR = "─".repeat(40);
+
+export function render(ast: DocumentAST): string {
+  const body = ast.blocks.map(renderBlock).join("");
+  return renderFrontmatter(ast.frontmatter) + body;
+}
+
+function renderFrontmatter(frontmatter: Frontmatter): string {
+  if (Object.keys(frontmatter).length === 0) {
+    return "";
+  }
+  return `${stringifyYaml(frontmatter)}${chalk.dim(SEPARATOR)}\n`;
+}
+
+function renderBlock(block: Block): string {
+  if (block.type === "heading") {
+    return `${styleHeading(block.level)(renderInline(block.children))}\n`;
+  }
+  return `${renderInline(block.children)}\n\n`;
+}
+
+// Each level gets a distinct style, tapering from bold at level 1 toward dim at level 6.
+function styleHeading(level: HeadingBlock["level"]): (text: string) => string {
+  switch (level) {
+    case 1:
+      return chalk.bold.underline;
+    case 2:
+      return chalk.bold;
+    case 3:
+      return chalk.bold.dim;
+    case 4:
+      return chalk.dim.underline;
+    case 5:
+      return chalk.dim;
+    case 6:
+      return chalk.dim.italic;
+  }
+}
+
+function renderInline(nodes: InlineNode[]): string {
+  return nodes.map((node) => node.value).join("");
+}

packages/bin/src/render_test.ts

@@ -0,0 +1,99 @@
+import { describe, expect, test } from "bun:test";
+import type { DocumentAST, HeadingBlock } from "@kitchen-md/core";
+import { render } from "./render.ts";
+
+describe("render", () => {
+  test("a heading renders its text followed by a single newline", () => {
+    const ast: DocumentAST = {
+      frontmatter: {},
+      blocks: [{ type: "heading", level: 2, children: [{ type: "text", value: "Method" }] }],
+      diagnostics: [],
+    };
+
+    expect(Bun.stripANSI(render(ast))).toBe("Method\n");
+  });
+
+  test("a paragraph renders its text followed by a blank line", () => {
+    const ast: DocumentAST = {
+      frontmatter: {},
+      blocks: [{ type: "paragraph", children: [{ type: "text", value: "Toast the bread." }] }],
+      diagnostics: [],
+    };
+
+    expect(Bun.stripANSI(render(ast))).toBe("Toast the bread.\n\n");
+  });
+
+  test("frontmatter renders as YAML before the body, followed by a separator rule", () => {
+    const ast: DocumentAST = {
+      frontmatter: { title: "Buttered Toast", servings: 2 },
+      blocks: [
+        { type: "heading", level: 1, children: [{ type: "text", value: "Buttered Toast" }] },
+      ],
+      diagnostics: [],
+    };
+
+    const stripped = Bun.stripANSI(render(ast));
+
+    expect(stripped).toContain("title: Buttered Toast");
+    expect(stripped).toContain("servings: 2");
+    expect(stripped).toContain("──────");
+
+    const titleIndex = stripped.indexOf("title: Buttered Toast");
+    const separatorIndex = stripped.indexOf("──────");
+    const bodyIndex = stripped.lastIndexOf("Buttered Toast");
+
+    expect(titleIndex).toBeLessThan(separatorIndex);
+    expect(separatorIndex).toBeLessThan(bodyIndex);
+  });
+
+  test("no frontmatter emits neither YAML nor a separator", () => {
+    const ast: DocumentAST = {
+      frontmatter: {},
+      blocks: [{ type: "paragraph", children: [{ type: "text", value: "Body only." }] }],
+      diagnostics: [],
+    };
+
+    const stripped = Bun.stripANSI(render(ast));
+
+    expect(stripped).toBe("Body only.\n\n");
+    expect(stripped).not.toContain("─");
+  });
+
+  test("blocks render in document order", () => {
+    const ast: DocumentAST = {
+      frontmatter: {},
+      blocks: [
+        { type: "heading", level: 1, children: [{ type: "text", value: "Title" }] },
+        { type: "paragraph", children: [{ type: "text", value: "First para." }] },
+        { type: "heading", level: 2, children: [{ type: "text", value: "Next" }] },
+      ],
+      diagnostics: [],
+    };
+
+    const stripped = Bun.stripANSI(render(ast));
+
+    expect(stripped.indexOf("Title")).toBeLessThan(stripped.indexOf("First para."));
+    expect(stripped.indexOf("First para.")).toBeLessThan(stripped.indexOf("Next"));
+  });
+
+  test("a heading renders its text at every level 1–6", () => {
+    const cases: [HeadingBlock["level"], string][] = [
+      [1, "Level One"],
+      [2, "Level Two"],
+      [3, "Level Three"],
+      [4, "Level Four"],
+      [5, "Level Five"],
+      [6, "Level Six"],
+    ];
+
+    for (const [level, title] of cases) {
+      const ast: DocumentAST = {
+        frontmatter: {},
+        blocks: [{ type: "heading", level, children: [{ type: "text", value: title }] }],
+        diagnostics: [],
+      };
+
+      expect(Bun.stripANSI(render(ast))).toBe(`${title}\n`);
+    }
+  });
+});

packages/bin/src/smoke_test.ts

@@ -1,6 +0,0 @@
-import { describe, test } from "bun:test";
-
-describe("smoke", () => {
-  test.todo("kitchen --help exits with code 0");
-  test.todo("kitchen parse <fixture> outputs structured JSON covering all annotation types");
-});