diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2612c5c..0061b25 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -31,6 +31,11 @@ jobs:
               exit 1
             }
           done
+      - name: Generate OpenCLI spec
+        run: node packages/cli/dist/index.js docgen --output packages/cli/opencli.json
+      - uses: bhouston/clidoc-action@v1
+        with:
+          files: packages/cli/opencli.json
       - run: pnpm tsc
       - run: pnpm lint
       - run: pnpm test --coverage
diff --git a/.gitignore b/.gitignore
index 406f191..b4ec419 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,4 @@ profile-output
 packages/hdrify-vscode-extension/media
 publish
 release-artifacts
+packages/cli/opencli.json
diff --git a/packages/cli/package.json b/packages/cli/package.json
index 4238da9..80df664 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -48,6 +48,8 @@
     "start": "node dist/index.js"
   },
   "dependencies": {
+    "@clidoc/core": "^1.0.0",
+    "@clidoc/yargs": "^0.1.0",
     "hdrify": "workspace:*",
     "sharp": "^0.34.5",
     "yargs": "^18.0.0",
diff --git a/packages/cli/src/index.ts b/packages/cli/src/index.ts
index 3885962..7674c04 100644
--- a/packages/cli/src/index.ts
+++ b/packages/cli/src/index.ts
@@ -1,13 +1,19 @@
 #!/usr/bin/env node
 
+import { readFileSync } from 'node:fs';
 import * as path from 'node:path';
 import { fileURLToPath } from 'node:url';
 import yargs from 'yargs';
 import { hideBin } from 'yargs/helpers';
 import { fileCommands } from 'yargs-file-commands';
+import { createDocgenCommand, fromYargs } from '@clidoc/yargs';
+import { handleOpenCliRequest, infoFromPackageJson } from '@clidoc/core';
+import type { OpenCliDocument } from '@clidoc/core';
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 const commandsDir = path.join(__dirname, 'commands');
+const pkg = JSON.parse(readFileSync(path.join(__dirname, '../package.json'), 'utf8'));
+const info = infoFromPackageJson(pkg);
 
 function isCommandError(msg: string): boolean {
   const lower = msg.toLowerCase();
@@ -24,10 +30,12 @@ function isCommandError(msg: string): boolean {
  * the caller handles exit codes.
  */
 export async function runCli(argv: string[]): Promise<unknown> {
+  let document: OpenCliDocument;
   const y = yargs(argv)
     .scriptName('hdrify')
     .usage('$0 <command> [options]')
     .command(await fileCommands({ commandDirs: [commandsDir] }))
+    .command(createDocgenCommand(() => document))
     .demandCommand(1, 'You must specify a command.')
     .help()
     .alias('h', 'help')
@@ -44,6 +52,8 @@ export async function runCli(argv: string[]): Promise<unknown> {
       if (err) throw err;
       throw new Error(msg);
     });
+  // generate the document once every command, including docgen, is registered
+  document = fromYargs(y, info);
 
   if (argv.length === 0) {
     console.error('You must specify a command.\n');
@@ -51,6 +61,10 @@ export async function runCli(argv: string[]): Promise<unknown> {
     return;
   }
 
+  if (await handleOpenCliRequest(argv, () => document)) {
+    return;
+  }
+
   try {
     return await y.parse();
   } catch (error) {
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 1d9cf60..c9043fc 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -96,6 +96,12 @@ importers:
 
   packages/cli:
     dependencies:
+      '@clidoc/core':
+        specifier: ^1.0.0
+        version: 1.0.0
+      '@clidoc/yargs':
+        specifier: ^0.1.0
+        version: 0.1.0
       hdrify:
         specifier: workspace:*
         version: link:../hdrify
@@ -496,6 +502,18 @@ packages:
     resolution: {integrity: sha512-6zABk/ECA/QYSCQ1NGiVwwbQerUCZ+TQbp64Q3AgmfNvurHH0j8TtXa1qbShXA6qqkpAj4V5W8pP6mLe1mcMqA==}
     engines: {node: '>=18'}
 
+  '@clidoc/core@0.1.0':
+    resolution: {integrity: sha512-VTkkyimkP+JFCGrebS45ykvieAC4uXLOf7e5kTK/Smjx0S3bjklPaUYba4NJ0VV2AV1+z19+qUrzREnjNKEP0A==}
+    engines: {node: '>=22.12.0'}
+
+  '@clidoc/core@1.0.0':
+    resolution: {integrity: sha512-oyUkkXQ7VNRO7fXXn388oYe77jE+rVZE8MVhXcZb3C9VlDwAlTx/EUTk1QjQMrnd7ecJxuryb/E3qsq8gLcqAQ==}
+    engines: {node: '>=22.12.0'}
+
+  '@clidoc/yargs@0.1.0':
+    resolution: {integrity: sha512-/h1+yuT75unZLKcimbOxBwKCc7RxFij8jE4h5UDMqrzfr8oaEbjtO9vTugoUW6WBd4Kqx7lUNIYOqqhdtpyKWA==}
+    engines: {node: '>=22.12.0'}
+
   '@cloudflare/kv-asset-handler@0.4.2':
     resolution: {integrity: sha512-SIOD2DxrRRwQ+jgzlXCqoEFiKOFqaPjhnNTGKXSRLvp1HiOvapLaFG2kEr9dYQTYe8rKrd9uvDUzmAITeNyaHQ==}
     engines: {node: '>=18.0.0'}
@@ -3687,6 +3705,14 @@ packages:
     resolution: {integrity: sha512-gOsf2YwSlleG6IjRYG2A7k0HmBMEo6qVNk9Bp/EaLgAJT5ngH6PXbqa4ItvnEwCm/velL5jAnQgsHsWnjhGmvw==}
     engines: {node: '>=18'}
 
+  ajv-formats@3.0.1:
+    resolution: {integrity: sha512-8iUql50EUR+uUcdRQ3HDqa6EVyo3docL8g5WJ3FNcWmu62IbkGUue/pEyLBW8VGKKucTPgqeks4fIU1DA4yowQ==}
+    peerDependencies:
+      ajv: ^8.0.0
+    peerDependenciesMeta:
+      ajv:
+        optional: true
+
   ajv@8.18.0:
     resolution: {integrity: sha512-PlXPeEWMXMZ7sPYOHqmDyCJzcfNrUr3fGNKtezX14ykXOEIvyK81d+qydx89KY5O71FKMPaQ2vBfBFI5NHR63A==}
 
@@ -7964,6 +7990,22 @@ snapshots:
 
   '@bcoe/v8-coverage@1.0.2': {}
 
+  '@clidoc/core@0.1.0':
+    dependencies:
+      ajv: 8.18.0
+      ajv-formats: 3.0.1(ajv@8.18.0)
+      yaml: 2.9.0
+
+  '@clidoc/core@1.0.0':
+    dependencies:
+      ajv: 8.18.0
+      ajv-formats: 3.0.1(ajv@8.18.0)
+      yaml: 2.9.0
+
+  '@clidoc/yargs@0.1.0':
+    dependencies:
+      '@clidoc/core': 0.1.0
+
   '@cloudflare/kv-asset-handler@0.4.2': {}
 
   '@colors/colors@1.5.0':
@@ -10861,6 +10903,10 @@ snapshots:
       clean-stack: 5.3.0
       indent-string: 5.0.0
 
+  ajv-formats@3.0.1(ajv@8.18.0):
+    optionalDependencies:
+      ajv: 8.18.0
+
   ajv@8.18.0:
     dependencies:
       fast-deep-equal: 3.1.3