diff --git a/README.md b/README.md
index 6fe8a01..76dfe2a 100644
--- a/README.md
+++ b/README.md
@@ -123,6 +123,8 @@ Kiro: copy `.kiro/steering/ponytail.md` to `~/.kiro/steering/` (global) or `.kir
 
 GitHub Copilot CLI: it already reads `AGENTS.md` and `.github/copilot-instructions.md` in a project, or copy the rules into `~/.copilot/copilot-instructions.md` to run ponytail in every project.
 
+Antigravity and VS Code with the Codex extension: both read `AGENTS.md`, which this repo ships, so it works from the repo root with no setup (`~/.codex/AGENTS.md` makes Codex global, `.agents/rules/` makes it an always-on rule in Antigravity).
+
 Which files map to which agent: [Agent portability](docs/agent-portability.md).
 
 ## Development
diff --git a/docs/agent-portability.md b/docs/agent-portability.md
index c603da6..82606c5 100644
--- a/docs/agent-portability.md
+++ b/docs/agent-portability.md
@@ -17,6 +17,8 @@ to load in a given agent.
 | Cline | `.clinerules/ponytail.md` | Project rule. |
 | GitHub Copilot | `.github/copilot-instructions.md` | Repository instruction file. |
 | GitHub Copilot CLI | `AGENTS.md`, `.github/copilot-instructions.md`, `~/.copilot/copilot-instructions.md` | Reads custom instructions: per-project from `AGENTS.md` or `.github/copilot-instructions.md`, or globally from `~/.copilot/copilot-instructions.md`. Instruction-tier (no `/ponytail` levels or hooks). |
+| Antigravity | `AGENTS.md` | Reads `AGENTS.md` at the repo root as always-on rules (like `.cursorrules`/`CLAUDE.md`); `.agents/rules/` also works for workspace rules. Instruction-tier. |
+| VS Code + Codex extension | `AGENTS.md` | The Codex extension reads `AGENTS.md` (repo root, or `~/.codex/AGENTS.md` globally). Instruction-tier; the full Codex plugin row above adds `/ponytail` levels and hooks. |
 | Kiro | `.kiro/steering/ponytail.md` | Steering rule; copy globally or into a project. |
 | Generic agents | `AGENTS.md` or `skills/*/SKILL.md` | Copy the compact rule file or load the skill files directly. |