py: add v0.3 refs (#1192)

Author: mdrxy

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "reference/external/html-docs"]
+	path = reference/external/html-docs
+	url = https://github.com/langchain-ai/langchain-api-docs-html.git

reference/README.md

@@ -5,3 +5,29 @@ Reference documentation is not consolidated into our primary Mintlify website ([
 Currently, a Vercel project serves the built HTML from the `dist/language` directories at [`reference.langchain.com/python`](https://reference.langchain.com/python) and [`reference.langchain.com/javascript`](https://reference.langchain.com/javascript).
 
 See the [`reference/python/README.md`](./python/README.md) and [`reference/javascript/README.md`](./javascript/README.md) files for more information on how each are built and deployed.
+
+## v0.3 Python HTML Reference Docs
+
+The v0.3 Python HTML reference docs are served at `/v0.3/python` and are maintained as a git submodule pointing to the [`langchain-api-docs-html`](https://github.com/langchain-ai/langchain-api-docs-html) repository.
+
+### Setup
+
+On first clone or when the submodule is added, initialize it:
+
+```bash
+git submodule update --init --recursive
+```
+
+### Updating v0.3 Python HTML Reference Docs
+
+```bash
+cd reference/external/html-docs
+git pull origin main
+cd ../..
+git add external/html-docs
+git commit -m "Update v0.3 Python HTML reference docs"
+```
+
+### Build Process
+
+The build script (`pnpm build:html-v03`) copies files from `external/html-docs/api_reference_build/html/` to `dist/v0.3/python/` during deployment.

reference/external/html-docs

@@ -3,9 +3,10 @@
   "private": true,
   "scripts": {
     "postinstall": "pnpm -C ./javascript install",
-    "build": "concurrently \"pnpm build:js\" \"pnpm build:py\"",
+    "build": "concurrently \"pnpm build:js\" \"pnpm build:py\" \"pnpm build:html-v03\"",
     "build:js": "pnpm -C ./javascript build",
     "build:py": "make -C ./python build",
+    "build:html-v03": "mkdir -p dist/v0.3/python && cp -r external/html-docs/api_reference_build/html/* dist/v0.3/python/",
     "preview": "vercel dev"
   },
   "packageManager": "pnpm@10.14.0",