diff --git a/.github/workflows/dco.yml b/.github/workflows/dco.yml
new file mode 100644
index 0000000..7960df3
--- /dev/null
+++ b/.github/workflows/dco.yml
@@ -0,0 +1,51 @@
+name: DCO
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  dco:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Check Signed-off-by on all commits
+        env:
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+        run: |
+          set -euo pipefail
+          commits=$(git rev-list --no-merges "$BASE_SHA".."$HEAD_SHA")
+          missing=0
+          for sha in $commits; do
+            body=$(git log -1 --format='%B' "$sha")
+            if ! echo "$body" | grep -qE '^Signed-off-by: .+ <.+@.+>'; then
+              short=$(git rev-parse --short "$sha")
+              subject=$(git log -1 --format='%s' "$sha")
+              echo "::error file=::Missing Signed-off-by on commit $short ($subject)"
+              missing=$((missing + 1))
+            fi
+          done
+          if [ "$missing" -gt 0 ]; then
+            echo ""
+            echo "❌ $missing commit(s) missing Signed-off-by."
+            echo ""
+            echo "To fix, rebase with signoff:"
+            echo "  git rebase --signoff origin/${{ github.base_ref }}"
+            echo "  git push --force-with-lease"
+            echo ""
+            echo "Or amend the last commit:"
+            echo "  git commit --amend -s --no-edit"
+            echo ""
+            echo "See: https://developercertificate.org/"
+            exit 1
+          fi
+          echo "✅ All commits have Signed-off-by"
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..b44713b
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,63 @@
+# Contributing to Dasher-Windows
+
+Thank you for your interest in improving Dasher for Windows! This guide covers
+the specifics of this repository. For project-wide conventions (code of
+conduct, security, RFCs), see the
+[organisation CONTRIBUTING](https://github.com/dasher-project/.github/blob/main/CONTRIBUTING.md).
+
+## Quick start
+
+```bash
+git clone --recurse-submodules https://github.com/dasher-project/Dasher-Windows.git
+cd Dasher-Windows
+dotnet build src/Dasher.Windows/Dasher.Windows.csproj
+```
+
+Requirements:
+
+- **.NET 10 SDK** (preview)
+- **Windows 10 18362+** (TargetFramework is `net10.0-windows10.0.18362.0`)
+- **Visual Studio 2022** or **Rider** (optional, for IDE support)
+
+## What lives where
+
+| Directory | Purpose |
+| :-- | :-- |
+| `src/Dasher.Windows/` | Main application (Avalonia UI + DasherCore P/Invoke) |
+| `src/Dasher.Windows/Views/` | AXAML windows and controls |
+| `src/Dasher.Windows/Engine/` | Native bridge (`NativeBridge.cs`), DasherCore interop |
+| `src/Dasher.Windows/Services/` | Analytics, updates, platform services |
+| `src/Dasher.Windows/Controls/` | Reusable UI controls (settings panel, etc.) |
+| `DasherCore/` | **Submodule** — the C++ engine (do not edit here; PR upstream) |
+
+## Code style
+
+- C# 13+ features are welcome (target framework is net10.0).
+- Enable `<Nullable>enable</Nullable>` — no `null` warnings.
+- 4-space indentation; no trailing whitespace.
+- Use `var` when the type is obvious from the right-hand side.
+- Use file-scoped namespaces.
+- AXAML uses `x:Static` for resource lookups and compiled bindings.
+
+## DasherCore changes
+
+DasherCore is a git submodule pointing to
+[dasher-project/DasherCore](https://github.com/dasher-project/DasherCore).
+**Do not modify it inside this repo.** If you need an engine change, open a PR
+against DasherCore directly, then bump the submodule pin here once merged.
+
+## Definition of Done
+
+- [ ] Builds cleanly (`dotnet build` with zero warnings)
+- [ ] Commits are signed off (DCO) — `git commit -s`
+- [ ] If you changed a user-visible capability, update the
+      [feature status matrix](https://dasher.at/status/) (`website` repo:
+      `src/data/feature-status.json`) — the PR template has a checkbox for this
+- [ ] If you changed UX/hardware interaction across platforms, check whether an
+      [RFC](https://github.com/dasher-project/governance/tree/main/rfcs) is needed
+
+## Pull request process
+
+1. Fork and branch from `main`.
+2. Open a PR — the org-level PR template will prompt you on parity, RFCs, and
+   the feature matrix.