diff --git a/README.md b/README.md
index 9334ea2..405d3a2 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@
-
+
@@ -101,6 +101,14 @@ Run OpenCode from a checkout of this repo (the plugin reuses its `hooks/` and `s
Injects the ruleset every turn at the active level; adds `/ponytail`, `/ponytail-review`, and `/ponytail-audit`. OpenCode also auto-loads this repo's `AGENTS.md`, so the rules hold even without the plugin. The plugin adds the `lite/full/ultra/off` levels.
+### Gemini CLI
+
+```bash
+gemini extensions install https://github.com/DietrichGebert/ponytail
+```
+
+Loads the ruleset as always-on context every session and registers `/ponytail` and `/ponytail-review`; the `skills/` ship too, activated when a task needs them.
+
That was it. He'd be proud. He won't say it.
Active every session. `/ponytail-review` finds what to delete in your diff, `/ponytail-audit` does the same for the whole repo. `/ponytail ultra` exists for when the codebase has wronged you personally. `/ponytail-help` explains the rest.
diff --git a/docs/agent-portability.md b/docs/agent-portability.md
index 6db5d17..1206031 100644
--- a/docs/agent-portability.md
+++ b/docs/agent-portability.md
@@ -11,6 +11,7 @@ to load in a given agent.
| Claude Code | `.claude-plugin/`, `commands/`, `hooks/` | Full plugin install with session activation, mode tracking, commands, and statusline support. |
| Codex | `.codex-plugin/plugin.json`, `hooks/hooks.json`, `hooks/`, `skills/` | Plugin install with the same skills plus lifecycle hooks for activation and mode tracking. |
| OpenCode | `.opencode/plugins/ponytail.mjs`, `.opencode/command/`, `hooks/`, `skills/` | Server plugin injects the ruleset each turn via `experimental.chat.system.transform` and persists `/ponytail` switches; reuses the shared instruction builder. |
+| Gemini CLI | `gemini-extension.json`, `AGENTS.md`, `commands/`, `skills/` | Extension manifest points `contextFileName` at `AGENTS.md` for always-on rules, and reuses the existing `commands/*.toml` (`/ponytail`, `/ponytail-review`) and `skills/`, which Gemini CLI auto-discovers. |
| Cursor | `.cursor/rules/ponytail.mdc` | Always-on project rule. |
| Windsurf | `.windsurf/rules/ponytail.md` | Project rule. |
| Cline | `.clinerules/ponytail.md` | Project rule. |
diff --git a/gemini-extension.json b/gemini-extension.json
new file mode 100644
index 0000000..5acba13
--- /dev/null
+++ b/gemini-extension.json
@@ -0,0 +1,6 @@
+{
+ "name": "ponytail",
+ "version": "4.2.0",
+ "description": "Lazy senior dev mode. Forces the simplest, shortest solution that actually works: YAGNI, stdlib first, no unrequested abstractions.",
+ "contextFileName": "AGENTS.md"
+}
diff --git a/tests/gemini-extension.test.js b/tests/gemini-extension.test.js
new file mode 100644
index 0000000..866f66d
--- /dev/null
+++ b/tests/gemini-extension.test.js
@@ -0,0 +1,67 @@
+#!/usr/bin/env node
+// Smoke test for the Gemini CLI adapter. The adapter is a single thin manifest
+// (gemini-extension.json) that reuses the repo's existing files: AGENTS.md for
+// always-on context, commands/*.toml for /ponytail + /ponytail-review, and
+// skills/ for the agent skills. This test fails if the manifest is removed,
+// loses its pinned version, or points contextFileName at a file that no longer
+// carries the load-bearing rules — i.e. if the adapter stops wiring ponytail.
+
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('fs');
+const path = require('path');
+
+const root = path.join(__dirname, '..');
+const MANIFEST = 'gemini-extension.json';
+const EXTENSION_NAME = 'ponytail';
+// Floating refs are a supply-chain footgun; the manifest version must be pinned.
+const PINNED_SEMVER = /^\d+\.\d+\.\d+$/;
+// Gemini auto-discovers these by directory; the manifest is only useful if they exist.
+const REUSED_COMMANDS = ['commands/ponytail.toml', 'commands/ponytail-review.toml'];
+const REUSED_SKILLS = ['skills/ponytail/SKILL.md'];
+// Same load-bearing phrases asserted by scripts/check-rule-copies.js: the file
+// contextFileName points at must actually carry the rules, not just exist.
+const RULE_INVARIANTS = [
+ 'lazy senior',
+ 'input validation at trust boundaries',
+ 'naive heuristic',
+];
+
+function read(relPath) {
+ return fs.readFileSync(path.join(root, relPath), 'utf8');
+}
+
+// Read inside each test (not at module scope) so a missing or malformed manifest
+// surfaces as a clean per-test assertion failure, not a load-time crash that
+// collapses every case into one unreadable stack trace.
+function loadManifest() {
+ assert.ok(fs.existsSync(path.join(root, MANIFEST)), `${MANIFEST} must exist`);
+ return JSON.parse(read(MANIFEST));
+}
+
+test('manifest names the ponytail extension with a pinned version', () => {
+ const manifest = loadManifest();
+ assert.equal(manifest.name, EXTENSION_NAME);
+ assert.match(manifest.version, PINNED_SEMVER);
+});
+
+test('version stays aligned with the other plugin manifests', () => {
+ const manifest = loadManifest();
+ const claude = JSON.parse(read('.claude-plugin/plugin.json'));
+ assert.equal(manifest.version, claude.version);
+});
+
+test('contextFileName resolves to a file carrying the ponytail rules', () => {
+ const manifest = loadManifest();
+ assert.ok(manifest.contextFileName, 'contextFileName must be set so rules load every session');
+ const context = read(manifest.contextFileName);
+ for (const phrase of RULE_INVARIANTS) {
+ assert.ok(context.includes(phrase), `context file missing rule invariant: "${phrase}"`);
+ }
+});
+
+test('the commands and skills the adapter reuses are present', () => {
+ for (const rel of [...REUSED_COMMANDS, ...REUSED_SKILLS]) {
+ assert.ok(fs.existsSync(path.join(root, rel)), `reused file missing: ${rel}`);
+ }
+});