diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
new file mode 100644
index 0000000..be0b08c
--- /dev/null
+++ b/.github/workflows/docs.yml
@@ -0,0 +1,49 @@
+name: Docs
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: docs-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v5
+      - uses: actions/setup-python@v7
+        with:
+          python-version: "3.13"
+      - name: Install
+        run: pip install -r docs/requirements.txt
+      - name: Build
+        run: mkdocs build --strict
+      - if: github.ref == 'refs/heads/main'
+        uses: actions/upload-pages-artifact@v5
+        with:
+          path: site
+
+  # Pull requests only build the site; main also deploys it.
+  deploy:
+    if: github.ref == 'refs/heads/main' && github.repository == 'ThinkFlowLab/system1-omni'
+    needs: build
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    permissions:
+      pages: write
+      id-token: write
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - id: deployment
+        uses: actions/deploy-pages@v5
diff --git a/.gitignore b/.gitignore
index 3857937..fd0f343 100644
--- a/.gitignore
+++ b/.gitignore
@@ -24,3 +24,7 @@ target
 .venv/
 __pycache__/
 .DS_Store
+
+# Documentation site build and environment
+/site/
+.venv-docs/
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index b06c929..53fa46c 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -49,3 +49,22 @@ A coding agent can help review the diff and identify issues, but contributors
 remain responsible for understanding the changes and verifying the results.
 Self-review helps maintainers focus on design and correctness; it does not
 replace maintainer review.
+
+## Documentation site
+
+The site at <https://thinkflowlab.github.io/system1-omni/> is built with MkDocs
+from the README, this guide, the frontend README and the Markdown files under
+`recipe/` and `docs/`. `mkdocs.yml` sets the navigation and, in `exclude_docs`,
+the published files. Pages keep their repository paths, so write links as
+relative paths that work on GitHub; links to files that are not published go to
+GitHub. Put images in `docs/assets/`.
+
+To run the check from the Docs workflow and preview the site, with Python 3.10 or
+later:
+
+```sh
+python3 -m venv .venv-docs
+.venv-docs/bin/pip install -r docs/requirements.txt
+.venv-docs/bin/mkdocs build --strict
+.venv-docs/bin/mkdocs serve    # http://127.0.0.1:8001/system1-omni/
+```
diff --git a/README.md b/README.md
index 76944aa..3d00ab3 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
 # System1-Omni
 
+Documentation: <https://thinkflowlab.github.io/system1-omni/>
+
 A community-maintained inference engine for prefill-only System1-Omni models, designed around a Rust frontend, model-owned execution, and high-performance CUDA and Metal backends.
 
 The Rust frontend forwards requests to a separately running model worker. In-repository model engines and GPU backends are not implemented yet.
diff --git a/docs/hooks.py b/docs/hooks.py
new file mode 100644
index 0000000..7f86b2d
--- /dev/null
+++ b/docs/hooks.py
@@ -0,0 +1,58 @@
+"""MkDocs hooks that build the site from the repository root.
+
+MkDocs rejects `docs_dir: .`, so the root is set here, after the config is
+checked, and `exclude_docs` in mkdocs.yml picks the published files. Pages keep
+their repository paths, so relative links work as they do on GitHub. Inline
+links to files that are not published, or to directories without a README, go
+to GitHub.
+"""
+
+import logging
+import posixpath
+import re
+from pathlib import Path
+
+log = logging.getLogger("mkdocs.hooks")
+ROOT = Path(__file__).resolve().parent.parent
+IMAGES = (".gif", ".jpeg", ".jpg", ".png", ".svg", ".webp")
+# The target of an inline link that is a relative path: ](path#anchor)
+LINK = re.compile(r"\]\((?![a-z][a-z0-9+.-]*:|#|/)([^)\s#]+)(#[^)\s]*)?\)")
+
+
+def on_config(config):
+    config.docs_dir = str(ROOT)
+    return config
+
+
+def on_serve(server, config, builder):
+    # Watch the published sources only, not target/ or virtual environments.
+    server.unwatch(config.docs_dir)
+    for name in ("README.md", "CONTRIBUTING.md", "docs", "recipe", "src"):
+        server.watch(str(ROOT / name))
+    return server
+
+
+def on_page_markdown(markdown, page, config, files):
+    base = posixpath.dirname(page.file.src_uri)
+    github = config.repo_url.rstrip("/")
+
+    def published(path):
+        file = files.get_file_from_path(path)
+        return file is not None and file.inclusion.is_included()
+
+    def fix(m):
+        target, anchor = m[1], m[2] or ""
+        path = posixpath.normpath(posixpath.join(base, target))
+        if path.split("/")[0] == ".." or not (ROOT / path).exists() or published(path):
+            return m[0]  # a page, or a missing file for MkDocs to report
+        if (ROOT / path).is_dir():
+            if published(posixpath.join(path, "README.md")):
+                return f"]({posixpath.join(target, 'README.md')}{anchor})"
+            return f"]({github}/tree/main/{path}{anchor})"
+        if path.lower().endswith(IMAGES):
+            # A GitHub page is not an image; the image has to be published.
+            log.warning("%s: %s is not published, see exclude_docs", page.file.src_uri, target)
+            return m[0]
+        return f"]({github}/blob/main/{path}{anchor})"
+
+    return LINK.sub(fix, markdown)
diff --git a/docs/requirements.txt b/docs/requirements.txt
new file mode 100644
index 0000000..4d732ea
--- /dev/null
+++ b/docs/requirements.txt
@@ -0,0 +1,3 @@
+mkdocs==1.6.1
+mkdocs-material==9.7.7
+pymdown-extensions==12.1
diff --git a/mkdocs.yml b/mkdocs.yml
new file mode 100644
index 0000000..2d63d2e
--- /dev/null
+++ b/mkdocs.yml
@@ -0,0 +1,53 @@
+site_name: System1-Omni
+site_url: https://thinkflowlab.github.io/system1-omni/
+repo_url: https://github.com/ThinkFlowLab/system1-omni
+edit_uri: edit/main/
+# The recipes run their workers on port 8000.
+dev_addr: 127.0.0.1:8001
+
+theme:
+  name: material
+  features:
+    - content.action.edit
+    - content.code.copy
+    - navigation.indexes
+    - navigation.sections
+    - search.highlight
+
+# docs/hooks.py builds the site from the repository root, so each page keeps its
+# repository path and relative links work here as they do on GitHub.
+hooks:
+  - docs/hooks.py
+# The published files; assets/ is the theme's. Nothing in hidden directories.
+exclude_docs: |
+  *
+  !/README.md
+  !/CONTRIBUTING.md
+  !/docs/**/*.md
+  !/docs/assets/**
+  !/recipe/**/*.md
+  !/src/frontend/README.md
+  !/assets/**
+  **/.*/**
+
+validation:
+  absolute_links: warn
+  unrecognized_links: warn
+  anchors: warn
+
+markdown_extensions:
+  - toc:
+      permalink: true
+      # Heading anchors as GitHub makes them.
+      slugify: !!python/object/apply:pymdownx.slugs.slugify
+        kwds:
+          case: lower
+  - pymdownx.superfences
+
+nav:
+  - Overview: README.md
+  - Frontend: src/frontend/README.md
+  - Recipes:
+      - recipe/README.md
+      - Laya text worker: recipe/laya/README.md
+  - Contributing: CONTRIBUTING.md