diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
new file mode 100644
index 0000000..a745f75
--- /dev/null
+++ b/.github/copilot-instructions.md
@@ -0,0 +1,3 @@
+# trails.cool — Copilot Instructions
+
+For full project context — including architecture, principles, tech stack, dev commands, testing strategy, code conventions, git workflow, and deployment — see [`CLAUDE.md`](../CLAUDE.md) at the repository root.
diff --git a/README.md b/README.md
index af848bf..36f7493 100644
--- a/README.md
+++ b/README.md
@@ -79,6 +79,7 @@ This project uses AI-assisted, spec-driven development. See
 |------|---------|
 | [cmux](https://cmux.dev) | Native macOS terminal for running multiple AI coding sessions |
 | [Claude Code](https://claude.ai/claude-code) | AI coding assistant (primary development tool) |
+| [GitHub Copilot](https://github.com/features/copilot) | AI coding assistant |
 | [Crit](https://github.com/tomasz-tomczyk/crit) | Browser-based inline code review |
 | [OpenSpec](https://openspec.dev) | Spec-driven development workflow |