feat(command): add /skill slash command for user-activated skill injection (#2488)

* feat(command): add /skill slash command for user-activated skill injection

* test(command): add tests for /skill slash command

* refactor(command): switch skill activation from /skill prefix to $-reference interceptor

nanobot/command/builtin.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import asyncio
 import os
+import re
 import sys
 
 from nanobot import __version__
@@ -11,6 +12,9 @@ from nanobot.bus.events import OutboundMessage
 from nanobot.command.router import CommandContext, CommandRouter
 from nanobot.utils.helpers import build_status_content
 
+# Pattern to match $skill-name tokens (word chars + hyphens)
+_SKILL_REF = re.compile(r"\$([A-Za-z][A-Za-z0-9_-]*)")
+
 
 async def cmd_stop(ctx: CommandContext) -> OutboundMessage:
     """Cancel all active tasks and subagents for the session."""
@@ -56,8 +60,10 @@ async def cmd_status(ctx: CommandContext) -> OutboundMessage:
         channel=ctx.msg.channel,
         chat_id=ctx.msg.chat_id,
         content=build_status_content(
-            version=__version__, model=loop.model,
-            start_time=loop._start_time, last_usage=loop._last_usage,
+            version=__version__,
+            model=loop.model,
+            start_time=loop._start_time,
+            last_usage=loop._last_usage,
             context_window_tokens=loop.context_window_tokens,
             session_msg_count=len(session.get_history(max_messages=0)),
             context_tokens_estimate=ctx_est,
@@ -70,18 +76,82 @@ async def cmd_new(ctx: CommandContext) -> OutboundMessage:
     """Start a fresh session."""
     loop = ctx.loop
     session = ctx.session or loop.sessions.get_or_create(ctx.key)
-    snapshot = session.messages[session.last_consolidated:]
+    snapshot = session.messages[session.last_consolidated :]
     session.clear()
     loop.sessions.save(session)
     loop.sessions.invalidate(session.key)
     if snapshot:
         loop._schedule_background(loop.memory_consolidator.archive_messages(snapshot))
     return OutboundMessage(
-        channel=ctx.msg.channel, chat_id=ctx.msg.chat_id,
+        channel=ctx.msg.channel,
+        chat_id=ctx.msg.chat_id,
         content="New session started.",
     )
 
 
+async def cmd_skill_list(ctx: CommandContext) -> OutboundMessage:
+    """List all available skills."""
+    loader = ctx.loop.context.skills
+    skills = loader.list_skills(filter_unavailable=False)
+    if not skills:
+        return OutboundMessage(
+            channel=ctx.msg.channel,
+            chat_id=ctx.msg.chat_id,
+            content="No skills found.",
+        )
+    lines = ["Available skills (use $<name> to activate):"]
+    for s in skills:
+        desc = loader._get_skill_description(s["name"])
+        available = loader._check_requirements(loader._get_skill_meta(s["name"]))
+        mark = "✓" if available else "✗"
+        lines.append(f"  {mark} {s['name']} — {desc}")
+    return OutboundMessage(
+        channel=ctx.msg.channel,
+        chat_id=ctx.msg.chat_id,
+        content="\n".join(lines),
+        metadata={"render_as": "text"},
+    )
+
+
+async def intercept_skill_refs(ctx: CommandContext) -> OutboundMessage | None:
+    """Scan message for $skill-name references and inject matching skills."""
+    refs = _SKILL_REF.findall(ctx.msg.content)
+    if not refs:
+        return None
+    loader = ctx.loop.context.skills
+    skill_names = {s["name"] for s in loader.list_skills(filter_unavailable=True)}
+    matched = []
+    for name in dict.fromkeys(refs):  # deduplicate, preserve order
+        if name in skill_names:
+            matched.append(name)
+    if not matched:
+        return None
+    # Strip matched $refs from the message
+    message = ctx.msg.content
+    for name in matched:
+        message = re.sub(rf"\${re.escape(name)}\b", "", message)
+    message = message.strip()
+    # Build injected content
+    skill_blocks = []
+    for name in matched:
+        content = loader.load_skill(name)
+        if content:
+            stripped = loader._strip_frontmatter(content)
+            skill_blocks.append(f'<skill-content name="{name}">\n{stripped}\n</skill-content>')
+    if not skill_blocks:
+        return None
+    names = ", ".join(f"'{n}'" for n in matched)
+    injected = (
+        f"<system-reminder>\n"
+        f"The user activated skill(s) {names} via $-reference. "
+        f"The following skill content was auto-appended by the system.\n"
+        + "\n".join(skill_blocks)
+        + "\n</system-reminder>"
+    )
+    ctx.msg.content = f"{injected}\n\n{message}" if message else injected
+    return None  # fall through to LLM
+
+
 async def cmd_help(ctx: CommandContext) -> OutboundMessage:
     """Return available slash commands."""
     return OutboundMessage(
@@ -100,6 +170,8 @@ def build_help_text() -> str:
         "/stop — Stop the current task",
         "/restart — Restart the bot",
         "/status — Show bot status",
+        "/skills — List available skills",
+        "$<name> — Activate a skill inline (e.g. $weather what's the forecast)",
         "/help — Show available commands",
     ]
     return "\n".join(lines)
@@ -113,3 +185,5 @@ def register_builtin_commands(router: CommandRouter) -> None:
     router.exact("/new", cmd_new)
     router.exact("/status", cmd_status)
     router.exact("/help", cmd_help)
+    router.exact("/skills", cmd_skill_list)
+    router.intercept(intercept_skill_refs)

tests/cli/test_skill_command.py

@@ -0,0 +1,236 @@
+"""Tests for /skills listing and $skill inline activation."""
+
+from __future__ import annotations
+
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from nanobot.bus.events import InboundMessage
+from nanobot.command.builtin import cmd_skill_list, intercept_skill_refs
+from nanobot.command.router import CommandContext
+
+
+def _make_loop():
+    """Create a minimal AgentLoop with mocked dependencies."""
+    from nanobot.agent.loop import AgentLoop
+    from nanobot.bus.queue import MessageBus
+
+    bus = MessageBus()
+    provider = MagicMock()
+    provider.get_default_model.return_value = "test-model"
+    workspace = MagicMock()
+    workspace.__truediv__ = MagicMock(return_value=MagicMock())
+
+    with (
+        patch("nanobot.agent.loop.ContextBuilder"),
+        patch("nanobot.agent.loop.SessionManager"),
+        patch("nanobot.agent.loop.SubagentManager"),
+    ):
+        loop = AgentLoop(bus=bus, provider=provider, workspace=workspace)
+    return loop, bus
+
+
+def _make_ctx(content: str, loop=None):
+    """Build a CommandContext for testing."""
+    if loop is None:
+        loop, _ = _make_loop()
+    msg = InboundMessage(channel="cli", sender_id="user", chat_id="direct", content=content)
+    return CommandContext(msg=msg, session=None, key=msg.session_key, raw=content, loop=loop)
+
+
+def _mock_skills_loader(skills=None, skill_content=None):
+    """Return a mock SkillsLoader with configurable data."""
+    loader = MagicMock()
+    loader.list_skills.return_value = skills or []
+    loader.load_skill.side_effect = lambda name: (skill_content or {}).get(name)
+    loader._get_skill_description.side_effect = lambda name: f"{name} description"
+    loader._get_skill_meta.return_value = {}
+    loader._check_requirements.return_value = True
+    loader._strip_frontmatter.side_effect = lambda c: c
+    return loader
+
+
+WEATHER_SKILLS = [
+    {"name": "weather", "path": "/skills/weather/SKILL.md", "source": "builtin"},
+]
+MULTI_SKILLS = [
+    {"name": "weather", "path": "/skills/weather/SKILL.md", "source": "builtin"},
+    {"name": "github", "path": "/skills/github/SKILL.md", "source": "builtin"},
+]
+
+
+class TestSkillList:
+    @pytest.mark.asyncio
+    async def test_lists_available_skills(self):
+        loop, _ = _make_loop()
+        loader = _mock_skills_loader(skills=MULTI_SKILLS)
+        loop.context = MagicMock()
+        loop.context.skills = loader
+
+        ctx = _make_ctx("/skills", loop=loop)
+        result = await cmd_skill_list(ctx)
+
+        assert result is not None
+        assert "weather" in result.content
+        assert "github" in result.content
+        assert "✓" in result.content
+        assert "$" in result.content  # hints about $ usage
+
+    @pytest.mark.asyncio
+    async def test_shows_unavailable_mark(self):
+        loop, _ = _make_loop()
+        loader = _mock_skills_loader(
+            skills=[{"name": "tmux", "path": "/skills/tmux/SKILL.md", "source": "builtin"}]
+        )
+        loader._check_requirements.return_value = False
+        loop.context = MagicMock()
+        loop.context.skills = loader
+
+        ctx = _make_ctx("/skills", loop=loop)
+        result = await cmd_skill_list(ctx)
+
+        assert "✗" in result.content
+        assert "tmux" in result.content
+
+    @pytest.mark.asyncio
+    async def test_no_skills(self):
+        loop, _ = _make_loop()
+        loader = _mock_skills_loader(skills=[])
+        loop.context = MagicMock()
+        loop.context.skills = loader
+
+        ctx = _make_ctx("/skills", loop=loop)
+        result = await cmd_skill_list(ctx)
+
+        assert "No skills found" in result.content
+
+
+class TestSkillInterceptor:
+    @pytest.mark.asyncio
+    async def test_injects_single_skill(self):
+        loop, _ = _make_loop()
+        loader = _mock_skills_loader(
+            skills=WEATHER_SKILLS,
+            skill_content={"weather": "Use the weather API."},
+        )
+        loop.context = MagicMock()
+        loop.context.skills = loader
+
+        ctx = _make_ctx("$weather what is the forecast", loop=loop)
+        result = await intercept_skill_refs(ctx)
+
+        assert result is None  # falls through to LLM
+        assert '<skill-content name="weather">' in ctx.msg.content
+        assert "Use the weather API." in ctx.msg.content
+        assert "what is the forecast" in ctx.msg.content
+
+    @pytest.mark.asyncio
+    async def test_injects_multiple_skills(self):
+        loop, _ = _make_loop()
+        loader = _mock_skills_loader(
+            skills=MULTI_SKILLS,
+            skill_content={
+                "weather": "Weather skill content.",
+                "github": "GitHub skill content.",
+            },
+        )
+        loop.context = MagicMock()
+        loop.context.skills = loader
+
+        ctx = _make_ctx("$weather $github do something", loop=loop)
+        result = await intercept_skill_refs(ctx)
+
+        assert result is None
+        assert '<skill-content name="weather">' in ctx.msg.content
+        assert '<skill-content name="github">' in ctx.msg.content
+        assert "do something" in ctx.msg.content
+        # Both skills wrapped in a single system-reminder
+        assert ctx.msg.content.count("<system-reminder>") == 1
+
+    @pytest.mark.asyncio
+    async def test_skill_ref_anywhere_in_message(self):
+        loop, _ = _make_loop()
+        loader = _mock_skills_loader(
+            skills=WEATHER_SKILLS,
+            skill_content={"weather": "Weather skill content."},
+        )
+        loop.context = MagicMock()
+        loop.context.skills = loader
+
+        ctx = _make_ctx("tell me $weather the forecast for NYC", loop=loop)
+        result = await intercept_skill_refs(ctx)
+
+        assert result is None
+        assert '<skill-content name="weather">' in ctx.msg.content
+        assert (
+            "tell me  the forecast for NYC" in ctx.msg.content
+            or "tell me the forecast for NYC" in ctx.msg.content
+        )
+
+    @pytest.mark.asyncio
+    async def test_no_match_passes_through(self):
+        loop, _ = _make_loop()
+        loader = _mock_skills_loader(skills=WEATHER_SKILLS)
+        loop.context = MagicMock()
+        loop.context.skills = loader
+
+        ctx = _make_ctx("just a normal message", loop=loop)
+        result = await intercept_skill_refs(ctx)
+
+        assert result is None
+        assert ctx.msg.content == "just a normal message"
+
+    @pytest.mark.asyncio
+    async def test_unknown_ref_ignored(self):
+        loop, _ = _make_loop()
+        loader = _mock_skills_loader(skills=WEATHER_SKILLS)
+        loop.context = MagicMock()
+        loop.context.skills = loader
+
+        ctx = _make_ctx("$nonexistent do something", loop=loop)
+        result = await intercept_skill_refs(ctx)
+
+        assert result is None
+        assert ctx.msg.content == "$nonexistent do something"
+
+    @pytest.mark.asyncio
+    async def test_deduplicates_refs(self):
+        loop, _ = _make_loop()
+        loader = _mock_skills_loader(
+            skills=WEATHER_SKILLS,
+            skill_content={"weather": "Weather skill content."},
+        )
+        loop.context = MagicMock()
+        loop.context.skills = loader
+
+        ctx = _make_ctx("$weather $weather forecast", loop=loop)
+        result = await intercept_skill_refs(ctx)
+
+        assert result is None
+        assert ctx.msg.content.count('<skill-content name="weather">') == 1
+
+    @pytest.mark.asyncio
+    async def test_dollar_amount_not_matched(self):
+        loop, _ = _make_loop()
+        loader = _mock_skills_loader(skills=WEATHER_SKILLS)
+        loop.context = MagicMock()
+        loop.context.skills = loader
+
+        ctx = _make_ctx("I have $100 in my account", loop=loop)
+        result = await intercept_skill_refs(ctx)
+
+        assert result is None
+        assert ctx.msg.content == "I have $100 in my account"
+
+
+class TestHelpIncludesSkill:
+    @pytest.mark.asyncio
+    async def test_help_shows_skill_commands(self):
+        loop, _ = _make_loop()
+        msg = InboundMessage(channel="cli", sender_id="user", chat_id="direct", content="/help")
+        response = await loop._process_message(msg)
+
+        assert response is not None
+        assert "/skills" in response.content
+        assert "$" in response.content