feat(command): add /skill slash command to list enabled skills

- Register /skill in BUILTIN_COMMAND_SPECS with wrench icon
- Add cmd_skill handler that lists skill names and descriptions
- Disabled skills are excluded from the output
- Add 6 tests covering empty list, names/descriptions, disabled
  filtering, fallback description, markdown output, and router
  registration

nanobot/command/builtin.py

@@ -98,6 +98,12 @@ BUILTIN_COMMAND_SPECS: tuple[BuiltinCommandSpec, ...] = (
         "Revert memory to a previous Dream snapshot.",
         "undo-2",
     ),
+    BuiltinCommandSpec(
+        "/skill",
+        "List skills",
+        "List all enabled skills available to the agent.",
+        "wrench",
+    ),
     BuiltinCommandSpec(
         "/help",
         "Show help",
@@ -642,6 +648,25 @@ async def cmd_pairing(ctx: CommandContext) -> OutboundMessage:
     )
 
 
+async def cmd_skill(ctx: CommandContext) -> OutboundMessage:
+    """List all enabled skills (name and description only)."""
+    loop = ctx.loop
+    skills = loop.context.skills.list_skills(filter_unavailable=False)
+    if not skills:
+        content = "No skills available."
+    else:
+        lines = [f"Available skills ({len(skills)}):", ""]
+        for entry in skills:
+            desc = loop.context.skills._get_skill_description(entry["name"])
+            lines.append(f"- **{entry['name']}** — {desc}")
+        content = "\n".join(lines)
+    return OutboundMessage(
+        channel=ctx.msg.channel,
+        chat_id=ctx.msg.chat_id,
+        content=content,
+        metadata=dict(ctx.msg.metadata or {}),
+    )
+
 async def cmd_help(ctx: CommandContext) -> OutboundMessage:
     """Return available slash commands."""
     return OutboundMessage(
@@ -681,6 +706,7 @@ def register_builtin_commands(router: CommandRouter) -> None:
     router.prefix("/dream-log ", cmd_dream_log)
     router.exact("/dream-restore", cmd_dream_restore)
     router.prefix("/dream-restore ", cmd_dream_restore)
+    router.exact("/skill", cmd_skill)
     router.exact("/help", cmd_help)
     router.exact("/pairing", cmd_pairing)
     router.prefix("/pairing ", cmd_pairing)

tests/command/test_skill_command.py

@@ -0,0 +1,138 @@
+"""Tests for the /skill built-in command."""
+
+from pathlib import Path
+from unittest.mock import MagicMock
+
+import pytest
+
+from nanobot.agent.loop import AgentLoop
+from nanobot.agent.skills import SkillsLoader
+from nanobot.bus.events import InboundMessage
+from nanobot.bus.queue import MessageBus
+from nanobot.command.builtin import cmd_skill, register_builtin_commands
+from nanobot.command.router import CommandContext, CommandRouter
+from nanobot.config.schema import ModelPresetConfig
+
+
+def _provider(default_model: str = "test-model") -> MagicMock:
+    provider = MagicMock()
+    provider.get_default_model.return_value = default_model
+    provider.generation = MagicMock()
+    provider.generation.max_tokens = 4096
+    provider.generation.temperature = 0.1
+    provider.generation.reasoning_effort = None
+    return provider
+
+
+def _make_loop(tmp_path: Path) -> AgentLoop:
+    return AgentLoop(
+        bus=MessageBus(),
+        provider=_provider(),
+        workspace=tmp_path,
+        model="test-model",
+        context_window_tokens=8000,
+        model_presets={
+            "default": ModelPresetConfig(
+                model="test-model",
+                max_tokens=4096,
+                context_window_tokens=8000,
+            ),
+        },
+    )
+
+
+def _ctx(loop: AgentLoop, raw: str = "/skill") -> CommandContext:
+    msg = InboundMessage(channel="cli", sender_id="user", chat_id="direct", content=raw)
+    return CommandContext(msg=msg, session=None, key=msg.session_key, raw=raw, args="", loop=loop)
+
+
+def _write_skill(base: Path, name: str, *, description: str = "", body: str = "# Skill\n") -> None:
+    skill_dir = base / name
+    skill_dir.mkdir(parents=True, exist_ok=True)
+    frontmatter = f"---\nname: {name}\n"
+    if description:
+        frontmatter += f"description: {description}\n"
+    frontmatter += "---\n\n"
+    (skill_dir / "SKILL.md").write_text(frontmatter + body, encoding="utf-8")
+
+
+def _loop_with_skills(tmp_path: Path) -> AgentLoop:
+    """Create a loop with an empty builtin dir so only workspace skills appear."""
+    loop = _make_loop(tmp_path)
+    empty_builtin = tmp_path / "empty_builtin"
+    empty_builtin.mkdir()
+    loop.context.skills = SkillsLoader(tmp_path, builtin_skills_dir=empty_builtin)
+    return loop
+
+
+@pytest.mark.asyncio
+async def test_skill_command_no_skills(tmp_path: Path) -> None:
+    loop = _loop_with_skills(tmp_path)
+    out = await cmd_skill(_ctx(loop))
+    assert out.content == "No skills available."
+
+
+@pytest.mark.asyncio
+async def test_skill_command_lists_names_and_descriptions(tmp_path: Path) -> None:
+    ws_skills = tmp_path / "skills"
+    ws_skills.mkdir()
+    _write_skill(ws_skills, "weather", description="Get current weather and forecasts")
+    _write_skill(ws_skills, "cron", description="Schedule recurring tasks")
+
+    loop = _loop_with_skills(tmp_path)
+    out = await cmd_skill(_ctx(loop))
+
+    assert "Available skills (2):" in out.content
+    assert "**weather** — Get current weather and forecasts" in out.content
+    assert "**cron** — Schedule recurring tasks" in out.content
+    # Must NOT contain file paths
+    assert ".md" not in out.content
+    assert "/skills/" not in out.content
+
+
+@pytest.mark.asyncio
+async def test_skill_command_excludes_disabled(tmp_path: Path) -> None:
+    ws_skills = tmp_path / "skills"
+    ws_skills.mkdir()
+    _write_skill(ws_skills, "alpha", description="Alpha skill")
+    _write_skill(ws_skills, "beta", description="Beta skill")
+
+    loop = _make_loop(tmp_path)
+    loop.context.skills.disabled_skills = {"alpha"}
+
+    out = await cmd_skill(_ctx(loop))
+
+    assert "alpha" not in out.content
+    assert "**beta** — Beta skill" in out.content
+
+
+@pytest.mark.asyncio
+async def test_skill_command_fallback_description(tmp_path: Path) -> None:
+    ws_skills = tmp_path / "skills"
+    ws_skills.mkdir()
+    _write_skill(ws_skills, "plain", description="", body="# Plain Skill\n")
+
+    loop = _loop_with_skills(tmp_path)
+    out = await cmd_skill(_ctx(loop))
+
+    assert "**plain** — plain" in out.content
+
+
+@pytest.mark.asyncio
+async def test_skill_command_no_render_as_text(tmp_path: Path) -> None:
+    """Output is markdown; CLI should render it (not forced as plain text)."""
+    loop = _make_loop(tmp_path)
+    out = await cmd_skill(_ctx(loop))
+    assert out.metadata.get("render_as") != "text"
+
+
+@pytest.mark.asyncio
+async def test_skill_command_registered_on_router(tmp_path: Path) -> None:
+    router = CommandRouter()
+    register_builtin_commands(router)
+    loop = _loop_with_skills(tmp_path)
+
+    out = await router.dispatch(_ctx(loop, "/skill"))
+
+    assert out is not None
+    assert "No skills available." in out.content