chore: scaffold agent-instructions repository layout

README.md

@@ -0,0 +1,19 @@
+# agent-instructions
+
+Personal, cross-repository, cross-harness AI-agent instructions and workflow notes.
+Not tied to any single project — repo-specific facts belong in that repo's own
+`.github/copilot-instructions.md`/`AGENTS.md`/etc., not here.
+
+## Layout
+
+One subdirectory per harness/tool, since conventions and file formats differ between them:
+
+- `copilot/` — GitHub Copilot CLI
+  - `instructions/` — files loaded globally by the CLI (symlinked from
+    `~/.copilot/instructions`)
+  - `model-guide.md` — current model comparison table (smartness/speed/cost), kept
+    separate from `instructions/` so it can be updated on its own schedule without
+    touching workflow rules that reference it
+
+Additional harness subdirectories (e.g. `claude/`, `cursor/`) can be added the same way
+as needed.