diff --git a/navi/core/registry.py b/navi/core/registry.py
index 4f80fcd..dc22862 100644
--- a/navi/core/registry.py
+++ b/navi/core/registry.py
@@ -15,6 +15,7 @@
     MemorySearchTool,
     SpawnAgentTool,
     SshExecTool,
+    SwitchProfileTool,
     TerminalTool,
     TodoTool,
     Tool,
@@ -125,8 +126,7 @@
     for p in ALL_PROFILES:
         profiles.register(p)
 
-    # SpawnAgentTool registered after profiles so it can resolve profile names.
-    # session_store may be None at build time (injected separately in deps.py).
+    # Tools that need session_store + profile_registry registered after both are built.
     spawn_tool = SpawnAgentTool(
         profile_registry=profiles,
         tool_registry=tools,
@@ -136,6 +136,12 @@
     )
     tools.register(spawn_tool, builtin=True)
 
+    switch_tool = SwitchProfileTool(
+        session_store=session_store,
+        profile_registry=profiles,
+    )
+    tools.register(switch_tool, builtin=True)
+
     backends = BackendRegistry()
     backends.register(
         "ollama",
diff --git a/navi/profiles/secretary.py b/navi/profiles/secretary.py
index 4788ab5..d3c809a 100644
--- a/navi/profiles/secretary.py
+++ b/navi/profiles/secretary.py
@@ -17,7 +17,7 @@
 For complex multi-part tasks (3+ tool calls): call todo(op="set", tasks=[...]) first, then execute step by step. Mark each step done/failed with todo(op="update") as you go.
 
 Output style: concise, structured. When researching, include sources. Match tone and format to what was asked.""",
-    enabled_tools=["todo", "web_search", "web_view", "http_request", "filesystem", "code_exec", "terminal", "image_view", "memory_search", "memory_forget", "reload_tools", "write_tool", "list_tools", "tool_manual", "spawn_agent"],
+    enabled_tools=["todo", "switch_profile", "web_search", "web_view", "http_request", "filesystem", "code_exec", "terminal", "image_view", "memory_search", "memory_forget", "reload_tools", "write_tool", "list_tools", "tool_manual", "spawn_agent"],
     model="gemma4:26b-a4b-it-q4_K_M",
     temperature=0.7,
     max_iterations=30,
diff --git a/navi/profiles/server_admin.py b/navi/profiles/server_admin.py
index 3565d38..b970e8a 100644
--- a/navi/profiles/server_admin.py
+++ b/navi/profiles/server_admin.py
@@ -21,7 +21,7 @@
 3. Before destructive or irreversible operations, state what you're about to do and why.
 
 When delegating to sub-agents: assign each a single host or a single domain of concern. Include exact connection details and expected output format in every briefing.""",
-    enabled_tools=["todo", "terminal", "filesystem", "http_request", "web_view", "web_search", "ssh_exec", "image_view", "memory_search", "memory_forget", "reload_tools", "write_tool", "list_tools", "tool_manual", "spawn_agent"],
+    enabled_tools=["todo", "switch_profile", "terminal", "filesystem", "http_request", "web_view", "web_search", "ssh_exec", "image_view", "memory_search", "memory_forget", "reload_tools", "write_tool", "list_tools", "tool_manual", "spawn_agent"],
     model="gemma4:26b-a4b-it-q4_K_M",
     temperature=0.2,
     max_iterations=30,
diff --git a/navi/profiles/smart_home.py b/navi/profiles/smart_home.py
index d9be7d4..115dae9 100644
--- a/navi/profiles/smart_home.py
+++ b/navi/profiles/smart_home.py
@@ -19,7 +19,7 @@
 1. For multi-step tasks (3+ tool calls): call todo(op="set", tasks=[...]) first — which entities, what to check or change, in what order. Mark each step with todo(op="update") as you go.
 2. Before writing any HA config to disk, validate structure in code_exec.
 3. Before toggling devices or triggering automations, state what will change and whether it's reversible.""",
-    enabled_tools=["todo", "http_request", "web_view", "filesystem", "code_exec", "terminal", "ssh_exec", "image_view", "memory_search", "memory_forget", "reload_tools", "write_tool", "list_tools", "tool_manual", "spawn_agent"],
+    enabled_tools=["todo", "switch_profile", "http_request", "web_view", "filesystem", "code_exec", "terminal", "ssh_exec", "image_view", "memory_search", "memory_forget", "reload_tools", "write_tool", "list_tools", "tool_manual", "spawn_agent"],
     model="gemma4:26b-a4b-it-q4_K_M",
     temperature=0.3,
     max_iterations=30,
diff --git a/navi/tools/__init__.py b/navi/tools/__init__.py
index b331b0d..6247474 100644
--- a/navi/tools/__init__.py
+++ b/navi/tools/__init__.py
@@ -9,6 +9,7 @@
 from .memory_forget import MemoryForgetTool
 from .memory_search import MemorySearchTool
 from .todo import TodoTool
+from .switch_profile import SwitchProfileTool
 from .web_search import WebSearchTool
 from .web_view import WebViewTool
 
@@ -27,4 +28,5 @@
     "MemoryForgetTool",
     "SpawnAgentTool",
     "TodoTool",
+    "SwitchProfileTool",
 ]
diff --git a/navi/tools/switch_profile.py b/navi/tools/switch_profile.py
new file mode 100644
index 0000000..6add542
--- /dev/null
+++ b/navi/tools/switch_profile.py
@@ -0,0 +1,65 @@
+"""Built-in tool for switching the active agent profile mid-session."""
+
+from navi.tools.base import Tool, ToolResult, current_session_id
+
+
+class SwitchProfileTool(Tool):
+    name = "switch_profile"
+    description = (
+        "Switch this session to a different agent profile. "
+        "Use when the task domain changes and another profile has better-suited tools or instructions. "
+        "The new profile (tools + system prompt) becomes active from the NEXT user message. "
+        "Always tell the user you switched and which profile is now active."
+    )
+    parameters = {
+        "type": "object",
+        "properties": {
+            "profile_id": {
+                "type": "string",
+                "description": "ID of the profile to switch to.",
+            }
+        },
+        "required": ["profile_id"],
+    }
+
+    def __init__(self, session_store, profile_registry) -> None:
+        self._sessions = session_store
+        self._profiles = profile_registry
+
+    async def execute(self, params: dict) -> ToolResult:
+        profile_id = (params.get("profile_id") or "").strip()
+        available = ", ".join(p.id for p in self._profiles.all())
+
+        try:
+            profile = self._profiles.get(profile_id)
+        except Exception:
+            return ToolResult(
+                success=False,
+                output="",
+                error=f"Profile '{profile_id}' not found. Available: {available}",
+            )
+
+        sid = current_session_id.get()
+        if not sid:
+            return ToolResult(success=False, output="", error="No active session context.")
+
+        session = await self._sessions.get(sid)
+        if session is None:
+            return ToolResult(success=False, output="", error="Session not found.")
+
+        if session.profile_id == profile_id:
+            return ToolResult(
+                success=True,
+                output=f"Already on profile '{profile.name}' — no change.",
+            )
+
+        session.profile_id = profile_id
+        await self._sessions.save(session)
+
+        return ToolResult(
+            success=True,
+            output=(
+                f"Switched to profile '{profile.name}' ({profile_id}). "
+                f"Its tools and system prompt are active from the next message."
+            ),
+        )
diff --git a/persona.txt b/persona.txt
index 4516712..6a4c74e 100644
--- a/persona.txt
+++ b/persona.txt
@@ -22,6 +22,16 @@
 
 write_tool reports success or the exact error. If there is an error, fix the code and call write_tool again. The tool is available from the NEXT user message. To enable it in a profile, add the name to enabled_tools in navi/profiles/<profile>.py.
 
+PROFILE SWITCHING:
+Each session has an active profile — it defines your available tools and system instructions. When the user's task clearly belongs to a different domain (e.g. switching from writing to server administration, or from admin work to home automation), call switch_profile with the appropriate profile_id.
+
+Rules:
+- Call list_tools or check the profiles available if unsure which profile_id to use.
+- The switch takes effect from the NEXT user message — your current tools are still available for this turn.
+- After switching, tell the user: which profile is now active and what it's for.
+- Don't switch for a single off-topic question. Switch when the session is clearly moving into a different domain.
+- Never switch back and forth repeatedly within one conversation.
+
 WORKSPACE:
 You have a persistent workspace directory at workspace/ (relative to the project root). Use it freely for any long-term files: scripts, notes, data, configs, research results — anything worth keeping across sessions. It is yours; the user will not clean it up. Do NOT write working files to the project root.