feat(install): add antigravity and grok harness targets

README.md

@@ -30,6 +30,7 @@ To install skills for selected harnesses, list them with commas:
 ```bash
 npx @3metajun/mstack --harness codex,claude
 npx @3metajun/mstack --harness opencode,pi
+npx @3metajun/mstack --harness antigravity,grok
 ```
 
 To install selected skills, add `--skill`:
@@ -81,7 +82,7 @@ in `~/.config/mstack/models.json`; the
 installer registers no hooks, so the hook comes only with the plugin.
 
 The installer remains the route for bare `/meta-mode` names, per-skill
-selection, and the shared Codex, OpenCode, and pi copy:
+selection, and the shared Codex, OpenCode, pi, and Grok copy:
 `npx @3metajun/mstack --harness claude`.
 
 ### Claude Desktop chat, Cowork, and claude.ai
@@ -190,13 +191,23 @@ The default directories are defined in
 | Claude Code | `~/.claude/skills/` | `HARNESS_SKILLS_CLAUDE_DIR` |
 | OpenCode | `~/.agents/skills/` | `HARNESS_SKILLS_OPENCODE_DIR` |
 | pi | `~/.agents/skills/` | `HARNESS_SKILLS_PI_DIR` |
+| Antigravity (`agy`) | `~/.gemini/antigravity-cli/skills/` | `HARNESS_SKILLS_ANTIGRAVITY_DIR` |
+| Grok | `~/.agents/skills/` | `HARNESS_SKILLS_GROK_DIR` |
 
-Codex, OpenCode and pi share one physical copy per skill by default. Updating
+Codex, OpenCode, pi and Grok share one physical copy per skill by default. Updating
 through any of these Harnesses updates that shared copy. Claude gets its own
 adapter output without a frontmatter `name`: Claude uses the directory name,
 while OpenCode skips that copy. No global Harness settings are changed.
 
-OpenCode and pi agent artifacts retain their native configuration roots.
+Antigravity does not read `~/.agents/skills/`, so it keeps its own canonical copy
+under `~/.gemini/antigravity-cli/skills/` and relies on the frontmatter `name`
+the canonical skills carry. Cursor already reads `~/.agents/skills/` and needs no
+separate target; see the [Harness adapter reference](./docs/harness-adapters.md).
+
+OpenCode and pi agent artifacts retain their native configuration roots. Grok
+agents go to `~/.grok/agents/`. Antigravity artifacts install beside its skills
+root (`~/.gemini/antigravity-cli/`); whether `agy` discovers agent files there is
+not verified, so treat that target as storage until you confirm it.
 `CLAUDE_CONFIG_DIR`, `XDG_CONFIG_HOME` and `PI_CODING_AGENT_DIR` still resolve
 native roots and legacy migration locations; the latter two no longer move
 the default shared skills. Use `HARNESS_SKILLS_*_DIR` for explicit skill paths.
@@ -312,6 +323,10 @@ npm run run-role -- --harness opencode --role explorer \
 
 Add `--execute` to run the command. SSH environments pass the prompt through
 strict POSIX quoting or a PowerShell encoded command, depending on `shell`.
+Harnesses whose CLI takes the prompt as the value of a flag (`agy --print`,
+`grok --single`) declare that flag as `runtime.promptArgs` in
+[`profiles/harnesses.json`](./profiles/harnesses.json), so the model and read-only
+arguments never land between the flag and the prompt.
 
 Model roles live in `~/.config/mstack/models.json`. Each role accepts a model
 string. The `reviewer` role also accepts a non-empty list of unique model strings.
@@ -358,10 +373,14 @@ default model unless you supply `--model`, `--parent-model`, or a `--file` with
 model choices. An inherited role in that file needs `--parent-model`. The live
 prompt checks a reply marker; it does not prove that the Harness loaded the skill
 or completed its workflow. These live calls always use `--read-only`.
-Codex, Claude Code, and pi use CLI-enforced tool restrictions.
+Codex, Claude Code, pi, and Grok use CLI-enforced tool restrictions; Grok keeps
+only `read_file`, `list_dir`, and `grep`.
 OpenCode selects its built-in `plan` agent, which denies direct edits but still
 allows shell commands in OpenCode 1.18; use a disposable checkout when its
-prompt-only write boundary is insufficient. A live check also needs that
+prompt-only write boundary is insufficient. Antigravity's `--mode plan` has the
+same limit: it is an agent mode, not a tool allowlist. In Antigravity 1.2.17 it
+left the workspace untouched but still wrote its own plan file under
+`~/.gemini/antigravity-cli/`. A live check also needs that
 Harness's credentials and configured model access.
 
 The Claude live path was verified with Claude Code 2.1.267, the Kiro-Pro

adapters/antigravity.json

@@ -0,0 +1 @@
+{}

adapters/grok.json

@@ -0,0 +1 @@
+{}

docs/harness-adapters.md

@@ -11,22 +11,41 @@ to the official documentation used for each entry.
 | Claude Code | `~/.claude/skills/` | `.claude/skills/` | `name`, `description`, `license`, `compatibility`, `metadata`, and Claude invocation fields |
 | OpenCode | `~/.agents/skills/`, `~/.config/opencode/skills/`, `~/.claude/skills/` | `.opencode/skills/` | `license`, `compatibility`, and `metadata` |
 | pi | `~/.agents/skills/`, `~/.pi/agent/skills/` | `.pi/skills/` | `license`, `compatibility`, `metadata`, `allowed-tools`, and `disable-model-invocation` |
+| Antigravity (`agy`) | `~/.gemini/config/skills/`, `~/.gemini/antigravity-cli/skills/` | `.gemini/skills/`, `.agents/skills/`, `.agent/skills/` | `name` (required) and `description`; other fields are not documented |
+| Grok | `~/.grok/skills/`, `~/.agents/skills/`, `~/.claude/skills/`, `~/.cursor/skills/` | `.grok/skills/`, `.agents/skills/`, `.claude/skills/`, `.cursor/skills/` | `name`, `description`, `license`, `compatibility`, `metadata`, `allowed-tools`, `user-invocable`, and `disable-model-invocation` |
+| Cursor | `~/.cursor/skills/`, `~/.agents/skills/` | `.cursor/skills/`, `.agents/skills/`, `.claude/skills/` | Agent Skills fields |
 
 Sources:
 
 - [Codex skills](https://learn.chatgpt.com/docs/build-skills) and [Codex subagents](https://learn.chatgpt.com/docs/agent-configuration/subagents)
 - [Claude Code skills](https://code.claude.com/docs/en/skills)
 - [OpenCode skills](https://opencode.ai/docs/skills)
 - [pi skills](https://pi.dev/docs/latest/skills)
+- Antigravity: the `agy` 1.2.16 CLI and T3 Code's skill discovery for it,
+  [`AntigravitySkills.ts`](https://github.com/pingdotgg/t3code/blob/main/apps/server/src/provider/Drivers/AntigravitySkills.ts)
+  and the [Antigravity provider guide](https://github.com/pingdotgg/t3code/blob/main/docs/user/providers-antigravity.md).
+  Antigravity publishes no skill-path reference, so the roots above come from
+  that implementation.
+- Grok: the Grok Build user guide shipped with the CLI (`docs/user-guide/08-skills.md`
+  under the Grok home directory), checked against `grok inspect --json` on 1.0.46,
+  which listed skills from `~/.agents/skills/`.
+- [Cursor skills](https://cursor.com/docs/context/skills)
 
 The canonical tree keeps the Agent Skills fields that all supported Harnesses
 can read. Claude Code accepts `metadata` but does not act on its contents, so
 `adapters/claude.json` removes that map and surfaces the logger requirement in
 the `compatibility` field instead. OpenCode and pi retain `metadata` because
 their official references support it.
 
-mstack installs one canonical copy in `~/.agents/skills/` for Codex, OpenCode
-and pi. Claude output omits frontmatter `name`; Claude's documented fallback
+mstack installs one canonical copy in `~/.agents/skills/` for Codex, OpenCode,
+pi and Grok. Cursor reads that directory as well, so it needs no installer
+target. Antigravity does not read `~/.agents/skills/` (the agent treats
+`.agents/skills/` only as a project directory), so its harness has its own
+canonical copy under `~/.gemini/antigravity-cli/skills/`. Antigravity requires
+the `name` field and a file named `SKILL.md`, which the canonical skills already
+satisfy, so `adapters/antigravity.json` and `adapters/grok.json` are empty. Grok
+also scans `~/.claude/skills/`; skills with the same name collapse to one entry.
+Claude output omits frontmatter `name`; Claude's documented fallback
 uses the directory name, so `/meta-mode` keeps its name. OpenCode requires an
 explicit name before registration and skips the Claude copy. This behavior
 was checked with OpenCode 1.18.30 using a named Claude control skill and an

profiles/environments.example.json

@@ -5,20 +5,26 @@
       "codex": "C:\\path\\to\\Fleet\\codex\\skills",
       "claude": "C:\\path\\to\\Fleet\\claude\\skills",
       "opencode": "C:\\path\\to\\Fleet\\opencode\\skills",
-      "pi": "C:\\path\\to\\Fleet\\pi\\agent\\skills"
+      "pi": "C:\\path\\to\\Fleet\\pi\\agent\\skills",
+      "antigravity": "C:\\path\\to\\Fleet\\antigravity\\skills",
+      "grok": "C:\\path\\to\\Fleet\\grok\\skills"
     },
     "artifacts": {
       "agents": {
         "codex": "C:\\path\\to\\Fleet\\codex\\agents",
         "claude": "C:\\path\\to\\Fleet\\shared\\agents",
         "opencode": "C:\\path\\to\\Fleet\\shared\\agents",
-        "pi": "C:\\path\\to\\Fleet\\shared\\agents"
+        "pi": "C:\\path\\to\\Fleet\\shared\\agents",
+        "antigravity": "C:\\path\\to\\Fleet\\antigravity\\agents",
+        "grok": "C:\\path\\to\\Fleet\\grok\\agents"
       },
       "meta-mode-tools": {
         "codex": "C:\\path\\to\\Fleet\\shared\\tools\\meta-mode",
         "claude": "C:\\path\\to\\Fleet\\shared\\tools\\meta-mode",
         "opencode": "C:\\path\\to\\Fleet\\shared\\tools\\meta-mode",
-        "pi": "C:\\path\\to\\Fleet\\shared\\tools\\meta-mode"
+        "pi": "C:\\path\\to\\Fleet\\shared\\tools\\meta-mode",
+        "antigravity": "C:\\path\\to\\Fleet\\shared\\tools\\meta-mode",
+        "grok": "C:\\path\\to\\Fleet\\shared\\tools\\meta-mode"
       }
     }
   },
@@ -31,20 +37,26 @@
       "codex": "/home/dev/.agents/skills",
       "claude": "/home/dev/.claude/skills",
       "opencode": "/home/dev/.agents/skills",
-      "pi": "/home/dev/.agents/skills"
+      "pi": "/home/dev/.agents/skills",
+      "antigravity": "/home/dev/.gemini/antigravity-cli/skills",
+      "grok": "/home/dev/.agents/skills"
     },
     "artifacts": {
       "agents": {
         "codex": "/home/dev/.codex/agents",
         "claude": "/home/dev/.claude/agents",
         "opencode": "/home/dev/.config/opencode/agents",
-        "pi": "/home/dev/.pi/agent/agents"
+        "pi": "/home/dev/.pi/agent/agents",
+        "antigravity": "/home/dev/.gemini/antigravity-cli/agents",
+        "grok": "/home/dev/.grok/agents"
       },
       "meta-mode-tools": {
         "codex": "/home/dev/.agents/tools/meta-mode",
         "claude": "/home/dev/.claude/tools/meta-mode",
         "opencode": "/home/dev/.agents/tools/meta-mode",
-        "pi": "/home/dev/.agents/tools/meta-mode"
+        "pi": "/home/dev/.agents/tools/meta-mode",
+        "antigravity": "/home/dev/.gemini/antigravity-cli/tools/meta-mode",
+        "grok": "/home/dev/.agents/tools/meta-mode"
       }
     }
   }

profiles/harnesses.json

@@ -47,5 +47,28 @@
       "modelArgs": ["--model", "{model}"],
       "readOnlyArgs": ["--tools", "read,grep,find,ls"]
     }
+  },
+  "antigravity": {
+    "directoryVariable": "HARNESS_SKILLS_ANTIGRAVITY_DIR",
+    "fallback": [".gemini", "antigravity-cli", "skills"],
+    "runtime": {
+      "command": "agy",
+      "headlessArgs": ["--output-format", "text"],
+      "promptArgs": ["--print"],
+      "modelArgs": ["--model", "{model}"],
+      "readOnlyArgs": ["--mode", "plan"]
+    }
+  },
+  "grok": {
+    "directoryVariable": "HARNESS_SKILLS_GROK_DIR",
+    "sharedSkills": true,
+    "fallback": [".grok", "skills"],
+    "runtime": {
+      "command": "grok",
+      "headlessArgs": ["--output-format", "plain"],
+      "promptArgs": ["--single"],
+      "modelArgs": ["--model", "{model}"],
+      "readOnlyArgs": ["--tools", "read_file,list_dir,grep", "--disallowed-tools", "search_tool,use_tool"]
+    }
   }
 }

profiles/models.example.json

@@ -12,6 +12,8 @@
     "codex": {},
     "claude": {},
     "opencode": {},
-    "pi": {}
+    "pi": {},
+    "antigravity": {},
+    "grok": {}
   }
 }

scripts/harness-targets.test.mjs

@@ -13,17 +13,39 @@ const home = resolve("fixture-home");
 test("default skills share a root while native roots retain harness-specific locations", () => {
   const roots = resolveHarnessRoots(registry, { env: {}, home });
   const shared = join(home, ".agents", "skills");
-  assert.deepEqual(roots.skills, { codex: shared, claude: join(home, ".claude", "skills"), opencode: shared, pi: shared });
+  assert.deepEqual(roots.skills, {
+    codex: shared,
+    claude: join(home, ".claude", "skills"),
+    opencode: shared,
+    pi: shared,
+    antigravity: join(home, ".gemini", "antigravity-cli", "skills"),
+    grok: shared,
+  });
   assert.deepEqual(roots.native, {
     codex: shared,
     claude: join(home, ".claude", "skills"),
     opencode: join(home, ".config", "opencode", "skills"),
     pi: join(home, ".pi", "agent", "skills"),
+    antigravity: join(home, ".gemini", "antigravity-cli", "skills"),
+    grok: join(home, ".grok", "skills"),
   });
   assert.deepEqual(roots.legacy, roots.native);
   assert.equal(roots.externalClaudeRoot, join(home, ".claude", "skills"));
 });
 
+test("Grok and Antigravity directory variables override roots and only Grok shares by default", () => {
+  const roots = resolveHarnessRoots(registry, {
+    home,
+    env: { HARNESS_SKILLS_GROK_DIR: "~/grok-explicit", HARNESS_SKILLS_ANTIGRAVITY_DIR: "~/antigravity-explicit" },
+  });
+  assert.equal(roots.skills.grok, join(home, "grok-explicit"));
+  assert.equal(roots.native.grok, join(home, "grok-explicit"));
+  assert.equal(roots.legacy.grok, join(home, ".grok", "skills"));
+  assert.equal(roots.skills.antigravity, join(home, "antigravity-explicit"));
+  assert.equal(roots.legacy.antigravity, join(home, ".gemini", "antigravity-cli", "skills"));
+  assert.throws(() => resolveHarnessRoots(registry, { home, env: { HARNESS_SKILLS_GROK_DIR: "relative" } }), /HARNESS_SKILLS_GROK_DIR must be an absolute path/);
+});
+
 test("configuration roots affect native and legacy locations without moving shared skills", () => {
   const roots = resolveHarnessRoots(registry, {
     home,
@@ -66,8 +88,8 @@ for (const explicit of [false, true]) {
     t.after(() => rmSync(root, { recursive: true, force: true }));
     const bin = join(root, "bin");
     mkdirSync(bin);
-    for (const harness of Object.keys(registry)) {
-      const executable = join(bin, `${harness}${process.platform === "win32" ? ".ps1" : ""}`);
+    for (const { runtime } of Object.values(registry)) {
+      const executable = join(bin, `${runtime.command}${process.platform === "win32" ? ".ps1" : ""}`);
       writeFileSync(executable, process.platform === "win32"
         ? 'if ($args.Count -eq 1 -and $args[0] -eq "--version") { Write-Output "fixture-cli 1.0"; exit 0 }; exit 9\n'
         : '#!/bin/sh\nif [ "$#" = 1 ] && [ "$1" = "--version" ]; then printf "fixture-cli 1.0\\n"; exit 0; fi\nexit 9\n');
@@ -79,17 +101,20 @@ for (const explicit of [false, true]) {
     if (explicit) {
       env.HARNESS_SKILLS_PI_DIR = join(root, "custom-pi-skills");
       env.HARNESS_SKILLS_OPENCODE_DIR = join(root, "custom-opencode-skills");
+      env.HARNESS_SKILLS_GROK_DIR = join(root, "custom-grok-skills");
+      env.HARNESS_SKILLS_ANTIGRAVITY_DIR = join(root, "custom-antigravity-skills");
     }
     const installed = spawnSync(process.execPath, [join(repository, "scripts", "install.mjs"), "--harness", "all", "--skill", "bro"], { cwd: root, env, encoding: "utf8" });
     assert.equal(installed.status, 0, installed.stderr);
     const smoked = spawnSync(process.execPath, [join(repository, "scripts", "smoke-harnesses.mjs"), "--harness", "all", "--skill", "bro", "--require-installed", "--json"], { cwd: root, env, encoding: "utf8" });
     assert.equal(smoked.status, 0, `${smoked.stderr}\n${smoked.stdout}`);
     const entries = JSON.parse(smoked.stdout);
-    assert.equal(entries.length, 4);
+    assert.equal(entries.length, 6);
     for (const entry of entries) {
       const expected = entry.harness === "claude" ? join(root, ".claude", "skills")
-        : explicit && ["pi", "opencode"].includes(entry.harness) ? join(root, `custom-${entry.harness}-skills`)
-          : join(root, ".agents", "skills");
+        : entry.harness === "antigravity" && !explicit ? join(root, ".gemini", "antigravity-cli", "skills")
+          : explicit && ["pi", "opencode", "grok", "antigravity"].includes(entry.harness) ? join(root, `custom-${entry.harness}-skills`)
+            : join(root, ".agents", "skills");
       assert.equal(entry.target, expected, entry.harness);
       assert.equal(entry.installed, true, entry.harness);
       assert.equal(entry.cli, "available", entry.harness);

scripts/install.mjs

@@ -56,11 +56,12 @@ function valueAfter(flag) {
 }
 
 if (args.includes("--help") || !args.includes("--harness")) {
-  console.log(`Usage: node scripts/install.mjs --harness <codex|claude|opencode|pi|all> [--environment <name>] [--skill <name[,name...]>] [--artifact <name[,name...]>] [--no-skills] [--dry-run] [--replace]
+  console.log(`Usage: node scripts/install.mjs --harness <codex|claude|opencode|pi|antigravity|grok|all> [--environment <name>] [--skill <name[,name...]>] [--artifact <name[,name...]>] [--no-skills] [--dry-run] [--replace]
 
 Installs canonical skills and optional artifacts into user-level harness directories.
 Artifacts: ${validArtifacts.join(", ")} (use --artifact all for installable artifacts).
-Codex, OpenCode and pi share ~/.agents/skills by default. Claude uses directory-based names.
+Codex, OpenCode, pi and Grok share ~/.agents/skills by default. Antigravity reads only its own
+~/.gemini/antigravity-cli/skills. Claude uses directory-based names.
 Use --migrate --replace to back up recognized legacy copies outside skill discovery roots.
 Existing directories are preserved unless --replace is supplied.`);
   process.exit(args.includes("--help") ? 0 : 1);

scripts/install.test.mjs

@@ -29,6 +29,8 @@ function fixture() {
       HARNESS_SKILLS_CLAUDE_DIR: join(root, "claude skills"),
       HARNESS_SKILLS_OPENCODE_DIR: join(root, "opencode skills"),
       HARNESS_SKILLS_PI_DIR: join(root, "pi skills"),
+      HARNESS_SKILLS_ANTIGRAVITY_DIR: join(root, "antigravity skills"),
+      HARNESS_SKILLS_GROK_DIR: join(root, "grok skills"),
     },
   };
 }
@@ -115,6 +117,8 @@ test("dry-run reports a plan without creating target directories", () => {
     assert.equal(existsSync(env.HARNESS_SKILLS_CODEX_DIR), false);
     assert.equal(existsSync(env.HARNESS_SKILLS_CLAUDE_DIR), false);
     assert.equal(existsSync(env.HARNESS_SKILLS_OPENCODE_DIR), false);
+    assert.equal(existsSync(env.HARNESS_SKILLS_ANTIGRAVITY_DIR), false);
+    assert.equal(existsSync(env.HARNESS_SKILLS_GROK_DIR), false);
   } finally {
     rmSync(root, { recursive: true, force: true });
   }
@@ -170,15 +174,20 @@ test("installs harness-specific frontmatter and preserves conflicts", () => {
     const claudePath = join(env.HARNESS_SKILLS_CLAUDE_DIR, "show-me-your-work", "SKILL.md");
     const opencodePath = join(env.HARNESS_SKILLS_OPENCODE_DIR, "show-me-your-work", "SKILL.md");
     const piPath = join(env.HARNESS_SKILLS_PI_DIR, "show-me-your-work", "SKILL.md");
+    const antigravityPath = join(env.HARNESS_SKILLS_ANTIGRAVITY_DIR, "show-me-your-work", "SKILL.md");
+    const grokPath = join(env.HARNESS_SKILLS_GROK_DIR, "show-me-your-work", "SKILL.md");
     const codex = readFileSync(codexPath, "utf8");
     const claude = readFileSync(claudePath, "utf8");
     const opencode = readFileSync(opencodePath, "utf8");
     const pi = readFileSync(piPath, "utf8");
+    const antigravity = readFileSync(antigravityPath, "utf8");
+    const grok = readFileSync(grokPath, "utf8");
     assert.match(codex, /^metadata:/m);
     assert.doesNotMatch(codex, /^compatibility:/m);
     assert.match(claude, /^compatibility:/m);
     assert.doesNotMatch(claude, /^metadata:/m);
-    for (const adapted of [opencode, pi]) {
+    for (const adapted of [opencode, pi, antigravity, grok]) {
+      assert.match(adapted, /^name: show-me-your-work$/m);
       assert.match(adapted, /^metadata:/m);
       assert.match(adapted, /^  requirements: Node\.js 18 or newer for scripts\/log\.mjs$/m);
       assert.doesNotMatch(adapted, /^compatibility:/m);
@@ -315,6 +324,8 @@ test("installs only selected skills", () => {
       env.HARNESS_SKILLS_CLAUDE_DIR,
       env.HARNESS_SKILLS_OPENCODE_DIR,
       env.HARNESS_SKILLS_PI_DIR,
+      env.HARNESS_SKILLS_ANTIGRAVITY_DIR,
+      env.HARNESS_SKILLS_GROK_DIR,
     ]) {
       assert.deepEqual(readdirSync(target).sort(), [
         "codebase-design",