From 0a6fb0e9547799617718ea59fcbcf9661d20f8da Mon Sep 17 00:00:00 2001
From: Travis Shears <t@travisshears.com>
Date: Fri, 20 Mar 2026 12:35:44 +0100
Subject: [PATCH] add readme

---
 README.md    | 58 ++++++++++++++++++++++++++++++++++++++++++++++++----
 bun.lock     |  3 +++
 index.ts     | 10 +++++++--
 package.json |  3 ++-
 4 files changed, 67 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index fe789fe..212a2a8 100644
--- a/README.md
+++ b/README.md
@@ -1,15 +1,65 @@
 # mermaid-diagram-creator
 
-To install dependencies:
+A CLI tool to convert Mermaid diagram files (.mmd) to SVG format.
+
+## Features
+
+- Convert Mermaid diagram text files to SVG
+- Easy command-line interface
+- Fast rendering with `beautiful-mermaid`
+- Input validation with Zod
+
+## Installation
+
+### 1. Set up the project
 
 ```bash
 bun install
 ```
 
-To run:
+### 2. Create symlink to your user bin directory
 
 ```bash
-bun run index.ts
+ln -s /Users/my_user_name/project_dir/mermaid-diagram-creator/bin/mmd-to-svg ~/.local/bin/mmd-to-svg
 ```
 
-This project was created using `bun init` in bun v1.2.21. [Bun](https://bun.com) is a fast all-in-one JavaScript runtime.
+## Usage
+
+```bash
+mmd-to-svg <input.mmd> <output.svg>
+```
+
+### Hot Reloading
+
+Using [entr](https://github.com/eradman/entr)
+
+```bash
+echo docs/diagrams/create_thing.mmd | entr mmd-to-svg ./docs/diagrams/create_thing.mmd ./docs/diagrams/create.svg
+```
+
+### Example
+
+```bash
+mmd-to-svg example.mmd diagram.svg
+```
+
+This will read the Mermaid diagram from `example.mmd` and output the rendered SVG to `diagram.svg`.
+
+### Example diagram file (example.mmd)
+
+```mermaid
+graph TD
+    A[Start] --> B{Decision}
+    B -->|Yes| C[Action]
+    B -->|No| D[End]
+```
+
+## Development
+
+Run directly:
+
+```bash
+bun index.ts example.mmd output.svg
+```
+
+Built with [Bun](https://bun.com) - a fast all-in-one JavaScript runtime.
diff --git a/bun.lock b/bun.lock
index 5c01dd5..532678e 100644
--- a/bun.lock
+++ b/bun.lock
@@ -5,6 +5,7 @@
       "name": "mermaid-diagram-creator",
       "dependencies": {
         "beautiful-mermaid": "^1.1.3",
+        "zod": "^4.3.6",
       },
       "devDependencies": {
         "@types/bun": "latest",
@@ -30,5 +31,7 @@
     "typescript": ["typescript@5.9.3", "", { "bin": { "tsc": "bin/tsc", "tsserver": "bin/tsserver" } }, "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw=="],
 
     "undici-types": ["undici-types@7.18.2", "", {}, "sha512-AsuCzffGHJybSaRrmr5eHr81mwJU3kjw6M+uprWvCXiNeN9SOGwQ3Jn8jb8m3Z6izVgknn1R0FTCEAP2QrLY/w=="],
+
+    "zod": ["zod@4.3.6", "", {}, "sha512-rftlrkhHZOcjDwkGlnUtZZkvaPHCsDATp4pGpuOOMDaTdDDXF91wuVDJoWoPsKX/3YPQ5fHuF3STjcYyKr+Qhg=="],
   }
 }
diff --git a/index.ts b/index.ts
index 08bbcee..353d19f 100644
--- a/index.ts
+++ b/index.ts
@@ -1,3 +1,4 @@
+import { z } from "zod";
 import { renderMermaidSVG } from "beautiful-mermaid";
 
 const args = process.argv.slice(2);
@@ -8,7 +9,10 @@ if (args.length < 2) {
   process.exit(1);
 }
 
-const [inputPath, outputPath] = args;
+const argsSchema = z.tuple([z.string(), z.string()]);
+
+const parsed = argsSchema.parse(args);
+const [inputPath, outputPath] = parsed;
 
 try {
   // Read the .mmd file
@@ -25,7 +29,9 @@ try {
   if (error instanceof Error && "code" in error && error.code === "ENOENT") {
     console.error(`✗ Input file not found: ${inputPath}`);
   } else {
-    console.error(`✗ Error: ${error instanceof Error ? error.message : String(error)}`);
+    console.error(
+      `✗ Error: ${error instanceof Error ? error.message : String(error)}`,
+    );
   }
   process.exit(1);
 }
diff --git a/package.json b/package.json
index 67b561b..f381a51 100644
--- a/package.json
+++ b/package.json
@@ -10,6 +10,7 @@
     "typescript": "^5"
   },
   "dependencies": {
-    "beautiful-mermaid": "^1.1.3"
+    "beautiful-mermaid": "^1.1.3",
+    "zod": "^4.3.6"
   }
 }