chore: replace some naked pointers

The coding guidelines explicitly prohibit the use of "naked"/C-style
pointers. However, there were some prominent examples in the kapi and
the core kernel source. This changeset replaces them with the
appropriate smart pointer types.

38 files changed, 153 insertions, 128 deletions

diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 97028855..2dbd613c 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -559,7 +559,7 @@ See the following code snippet for examples:
 .. code-block:: cpp
 
    [[nodiscard]] auto children() const -> kstd::vector<kstd::shared_ptr<device>>;
-   [[nodiscard]] auto resolve(kapi::capabilities::facet_id id, std::string_view name) -> void *;
+   [[nodiscard]] auto resolve(kapi::capabilities::facet_id id, std::string_view name) -> kstd::observer_ptr<void>;
    [[nodiscard]] auto request_resource(resource_type type, std::size_t index = 0) const -> kstd::result<resource>;
 
 ``constexpr`` and ``constinit``
diff --git a/arch/x86_64/arch/devices/cpu/core.cpp b/arch/x86_64/arch/devices/cpu/core.cpp
index ac06850e..13d4652d 100644
--- a/arch/x86_64/arch/devices/cpu/core.cpp
+++ b/arch/x86_64/arch/devices/cpu/core.cpp
@@ -6,6 +6,7 @@
 #include <kapi/devices.hpp>
 
 #include <kstd/format.hpp>
+#include <kstd/memory.hpp>
 
 #include <cstddef>
 #include <cstdint>
@@ -29,11 +30,11 @@ namespace arch::devices::cpu
     return m_id;
   }
 
-  auto core::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto core::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == bus::core_signature::id)
     {
-      return static_cast<bus::core_signature *>(this);
+      return kstd::make_observer<bus::core_signature>(this);
     }
 
     return device::query_facet(facet);
diff --git a/arch/x86_64/arch/devices/cpu/core.hpp b/arch/x86_64/arch/devices/cpu/core.hpp
index cd5ac65c..ad965da1 100644
--- a/arch/x86_64/arch/devices/cpu/core.hpp
+++ b/arch/x86_64/arch/devices/cpu/core.hpp
@@ -6,6 +6,8 @@
 #include <kapi/capabilities/facet_id.hpp>
 #include <kapi/devices.hpp>
 
+#include <kstd/memory.hpp>
+
 #include <cstddef>
 #include <cstdint>
 
@@ -20,7 +22,7 @@ namespace arch::devices::cpu
     [[nodiscard]] auto hardware_id() const noexcept -> std::uint64_t override;
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
 
   private:
     std::uint64_t m_id;
diff --git a/arch/x86_64/arch/devices/cpu/lapic.cpp b/arch/x86_64/arch/devices/cpu/lapic.cpp
index 280ebbca..d8571a8f 100644
--- a/arch/x86_64/arch/devices/cpu/lapic.cpp
+++ b/arch/x86_64/arch/devices/cpu/lapic.cpp
@@ -6,6 +6,7 @@
 #include <kapi/devices.hpp>
 
 #include <kstd/format.hpp>
+#include <kstd/memory.hpp>
 
 #include <cstddef>
 #include <cstdint>
@@ -29,11 +30,11 @@ namespace arch::devices::cpu
     return m_is_bsp;
   }
 
-  auto lapic::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto lapic::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == bus::lapic_signature::id)
     {
-      return static_cast<bus::lapic_signature *>(this);
+      return kstd::make_observer<bus::lapic_signature>(this);
     }
 
     return device::query_facet(facet);
diff --git a/arch/x86_64/arch/devices/cpu/lapic.hpp b/arch/x86_64/arch/devices/cpu/lapic.hpp
index 52ae40ae..3f91968e 100644
--- a/arch/x86_64/arch/devices/cpu/lapic.hpp
+++ b/arch/x86_64/arch/devices/cpu/lapic.hpp
@@ -6,6 +6,8 @@
 #include <kapi/capabilities/facet_id.hpp>
 #include <kapi/devices.hpp>
 
+#include <kstd/memory.hpp>
+
 #include <cstddef>
 #include <cstdint>
 
@@ -20,7 +22,7 @@ namespace arch::devices::cpu
     [[nodiscard]] auto is_bsp() const noexcept -> bool override;
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
 
   private:
     std::uint64_t m_id;
diff --git a/arch/x86_64/arch/devices/pit.cpp b/arch/x86_64/arch/devices/pit.cpp
index 83443c93..6de23865 100644
--- a/arch/x86_64/arch/devices/pit.cpp
+++ b/arch/x86_64/arch/devices/pit.cpp
@@ -5,6 +5,8 @@
 #include <kapi/capabilities/facet_id.hpp>
 #include <kapi/devices.hpp>
 
+#include <kstd/memory.hpp>
+
 #include <string_view>
 
 namespace arch::devices
@@ -19,11 +21,11 @@ namespace arch::devices
     return "pit";
   }
 
-  auto pit::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto pit::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == arch::bus::isa_signature::id)
     {
-      return static_cast<arch::bus::isa_signature *>(this);
+      return kstd::make_observer<arch::bus::isa_signature>(this);
     }
 
     return kapi::devices::device::query_facet(facet);
diff --git a/arch/x86_64/arch/devices/pit.hpp b/arch/x86_64/arch/devices/pit.hpp
index 08bf423a..ddd6d8a3 100644
--- a/arch/x86_64/arch/devices/pit.hpp
+++ b/arch/x86_64/arch/devices/pit.hpp
@@ -6,6 +6,8 @@
 #include <kapi/capabilities/facet_id.hpp>
 #include <kapi/devices.hpp>
 
+#include <kstd/memory.hpp>
+
 #include <string_view>
 
 namespace arch::devices
@@ -25,7 +27,7 @@ namespace arch::devices
     [[nodiscard]] auto isa_name() const -> std::string_view override;
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
   };
 
 }  // namespace arch::devices
diff --git a/arch/x86_64/arch/drivers/cpu/lapic.cpp b/arch/x86_64/arch/drivers/cpu/lapic.cpp
index c02c3df6..3b7c2d45 100644
--- a/arch/x86_64/arch/drivers/cpu/lapic.cpp
+++ b/arch/x86_64/arch/drivers/cpu/lapic.cpp
@@ -104,7 +104,7 @@ namespace arch::drivers::cpu
 
   auto lapic::probe(kapi::devices::device & device) -> kstd::result<void>
   {
-    auto * signature = device.facet<arch::bus::lapic_signature>();
+    auto const signature = device.facet<arch::bus::lapic_signature>();
     if (!signature)
     {
       return kstd::failure(make_error_code(kstd::errc::invalid_argument));
@@ -142,8 +142,8 @@ namespace arch::drivers::cpu
 
       write_register(registers::spurious_interrupt_vector, lapic_enable_bit | spurious_interrupt_vector);
 
-      kstd::println("[ARCH:DRV] LAPIC initialized. version: {#x} | max_lvt_entry: {} | eoi_suppression: {:s}",
-                    version, highest_lvt_entry_index, supports_eoi_broadcast_suppression);
+      kstd::println("[ARCH:DRV] LAPIC initialized. version: {#x} | max_lvt_entry: {} | eoi_suppression: {:s}", version,
+                    highest_lvt_entry_index, supports_eoi_broadcast_suppression);
     }
     else
     {
@@ -172,11 +172,11 @@ namespace arch::drivers::cpu
     *reg = value;
   }
 
-  auto lapic::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto lapic::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == arch::bus::lapic_claim::id)
     {
-      return static_cast<arch::bus::lapic_claim *>(this);
+      return kstd::make_observer<arch::bus::lapic_claim>(this);
     }
 
     return kapi::devices::driver::query_facet(facet);
diff --git a/arch/x86_64/arch/drivers/cpu/lapic.hpp b/arch/x86_64/arch/drivers/cpu/lapic.hpp
index 678d364a..52533d9a 100644
--- a/arch/x86_64/arch/drivers/cpu/lapic.hpp
+++ b/arch/x86_64/arch/drivers/cpu/lapic.hpp
@@ -8,6 +8,7 @@
 #include <kapi/memory.hpp>
 #include <kapi/tracked_mutex.hpp>
 
+#include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 
 #include <cstddef>
@@ -27,7 +28,7 @@ namespace arch::drivers::cpu
     [[nodiscard]] auto name() const noexcept -> std::string_view override;
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
 
   private:
     enum struct registers : std::ptrdiff_t;
diff --git a/arch/x86_64/arch/drivers/pit.cpp b/arch/x86_64/arch/drivers/pit.cpp
index e6e98796..6a768fc9 100644
--- a/arch/x86_64/arch/drivers/pit.cpp
+++ b/arch/x86_64/arch/drivers/pit.cpp
@@ -124,11 +124,11 @@ namespace arch::drivers
     return kapi::interrupts::status::handled;
   }
 
-  auto pit::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto pit::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == arch::bus::isa_claim::id)
     {
-      return static_cast<arch::bus::isa_claim *>(this);
+      return kstd::make_observer<arch::bus::isa_claim>(this);
     }
 
     return kapi::devices::driver::query_facet(facet);
diff --git a/arch/x86_64/arch/drivers/pit.hpp b/arch/x86_64/arch/drivers/pit.hpp
index ad8add4b..f5be5a17 100644
--- a/arch/x86_64/arch/drivers/pit.hpp
+++ b/arch/x86_64/arch/drivers/pit.hpp
@@ -33,7 +33,7 @@ namespace arch::drivers
     [[nodiscard]] auto name() const noexcept -> std::string_view override;
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
 
   private:
     struct data
diff --git a/docs/briefs/tb0003-facet-based-capability-dispatch.rst b/docs/briefs/tb0003-facet-based-capability-dispatch.rst
index 2cace2f3..70d183d0 100644
--- a/docs/briefs/tb0003-facet-based-capability-dispatch.rst
+++ b/docs/briefs/tb0003-facet-based-capability-dispatch.rst
@@ -76,12 +76,12 @@ Querying a Single Object
 
    struct device : kstd::enable_shared_from_this<device>
    {
-     [[nodiscard]] auto facet(kapi::capabilities::facet_id id) noexcept -> void *;
+     [[nodiscard]] auto facet(kapi::capabilities::facet_id id) noexcept -> kstd::observer_ptr<void>;
 
      template<typename FacetType>
      [[nodiscard]] auto facet() -> FacetType *
      {
-       return static_cast<FacetType *>(facet(FacetType::id));
+       return kstd::observer_ptr{static_cast<FacetType *>(facet(FacetType::id).get())};
      }
 
      template<typename FacetType>
@@ -91,7 +91,7 @@ Querying a Single Object
      }
 
    protected:
-     auto virtual query_facet(kapi::capabilities::facet_id facet) -> void *;
+     auto virtual query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>;
    };
 
 The base implementation of ``query_facet()`` simply returns ``nullptr``.
@@ -106,15 +106,15 @@ A concrete device overrides it, checks the requested id against every facet it s
      [[nodiscard]] auto isa_name() const -> std::string_view override;
 
    protected:
-     auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+     auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
    };
 
    // arch/x86_64/arch/devices/pit.cpp
-   auto pit::query_facet(kapi::capabilities::facet_id facet) -> void *
+   auto pit::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
    {
      if (facet == arch::bus::isa_signature::id)
      {
-       return static_cast<arch::bus::isa_signature *>(this);
+       return kstd::make_observer<arch::bus::isa_signature>(this);
      }
      return kapi::devices::device::query_facet(facet);   // <-- the delegation
    }
@@ -174,10 +174,10 @@ A device is not only queried for identification facets. ``bus`` itself answers t
 .. code-block:: cpp
 
    // kernel/kapi/devices/bus.cpp
-   auto bus::query_facet(kapi::capabilities::facet_id facet) -> void *
+   auto bus::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
    {
-     if (facet == bus::id) { return this; }
-     else if (facet == bus_protocol::id) { return m_protocol; }
+     if (facet == bus::id) { return kstd::observer_ptr{this}; }
+     else if (facet == bus_protocol::id) { return kstd::observer_ptr{m_protocol}; }
      return device::query_facet(facet);
    }
 
@@ -209,7 +209,7 @@ Everything above answers "does *this specific* device or driver support facet X"
      auto withdraw(device const & device, kapi::capabilities::facet_id id) -> void;
 
      [[nodiscard]] auto all(kapi::capabilities::facet_id id) const -> kstd::vector<entry>;
-     [[nodiscard]] auto resolve(kapi::capabilities::facet_id id, std::string_view name) -> void *;
+     [[nodiscard]] auto resolve(kapi::capabilities::facet_id id, std::string_view name) -> kstd::observer_ptr<void>;
 
      auto subscribe(kstd::weak_ptr<facet_registry_observer> observer) -> void;
      // ...
@@ -281,11 +281,11 @@ The two device-model facets already shown (``isa_signature``/``isa_claim``, ``bl
      }
 
    protected:
-     auto query_facet(kapi::capabilities::facet_id facet) -> void * override
+     auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override
      {
        if (facet == kapi::sensors::temperature_sensor::id)
        {
-         return static_cast<kapi::sensors::temperature_sensor *>(this);
+         return kstd::make_observer<kapi::sensors::temperature_sensor>(this);
        }
        return kapi::devices::device::query_facet(facet);   // never forget this line
      }
@@ -344,7 +344,7 @@ Capability query without a language-provided RTTI mechanism is a solved problem,
 COM's ``IUnknown::QueryInterface``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-This is the closest real-world relative of facet dispatch, and almost certainly its distant conceptual ancestor. Every COM object implements ``HRESULT QueryInterface(REFIID riid, void ** ppvObject)``: given a 128-bit interface identifier (a GUID) rather than a string, it returns a pointer to that interface or an error [2]_. The shape is identical — an opaque object, a caller-supplied tag, an untyped-then-cast pointer back, no shared base class needed to know about every possible interface in advance. The differences are informative rather than superficial: COM's tags are GUIDs, generated to be globally, statistically unique, specifically to avoid the collision risk a string tag carries (see *Drawbacks*, below); ``QueryInterface`` is reference-counted (``AddRef``/``Release``) as part of the same call, because COM objects can be shared across process and apartment boundaries in ways a kernel device tree is not; and COM has a formal rule that interface identity, once shipped, can never change shape — a modified interface gets a new GUID rather than breaking existing implementers. TeachOS has no equivalent discipline yet (also noted below).
+This is the closest real-world relative of facet dispatch, and almost certainly its distant conceptual ancestor. Every COM object implements ``HRESULT QueryInterface(REFIID riid, void * ppvObject)``: given a 128-bit interface identifier (a GUID) rather than a string, it returns a pointer to that interface or an error [2]_. The shape is identical — an opaque object, a caller-supplied tag, an untyped-then-cast pointer back, no shared base class needed to know about every possible interface in advance. The differences are informative rather than superficial: COM's tags are GUIDs, generated to be globally, statistically unique, specifically to avoid the collision risk a string tag carries (see *Drawbacks*, below); ``QueryInterface`` is reference-counted (``AddRef``/``Release``) as part of the same call, because COM objects can be shared across process and apartment boundaries in ways a kernel device tree is not; and COM has a formal rule that interface identity, once shipped, can never change shape — a modified interface gets a new GUID rather than breaking existing implementers. TeachOS has no equivalent discipline yet (also noted below).
 
 UEFI Protocols
 ~~~~~~~~~~~~~~~~
diff --git a/docs/guides/device-drivers.rst b/docs/guides/device-drivers.rst
index 3d3da182..a4bfe433 100644
--- a/docs/guides/device-drivers.rst
+++ b/docs/guides/device-drivers.rst
@@ -143,14 +143,14 @@ TeachOS's simplest real bus, ``kernel::bus::pseudo`` (``kernel/kernel/bus/pseudo
    {
      explicit pseudo(kstd::string name);
    protected:
-     auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+     auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
    private:
      pseudo_signature m_signature{*this};
    };
 
-   auto pseudo::query_facet(kapi::capabilities::facet_id facet) -> void *
+   auto pseudo::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
    {
-     if (facet == kernel::bus::pseudo_signature::id) { return &m_signature; }
+     if (facet == kernel::bus::pseudo_signature::id) { return kstd::observer_ptr{&m_signature}; }
      return device::query_facet(facet);
    }
 
diff --git a/kapi/kapi/boot_modules/device.hpp b/kapi/kapi/boot_modules/device.hpp
index 4bdd34e4..7d3e3d6e 100644
--- a/kapi/kapi/boot_modules/device.hpp
+++ b/kapi/kapi/boot_modules/device.hpp
@@ -6,6 +6,8 @@
 #include <kapi/devices.hpp>
 #include <kapi/memory.hpp>
 
+#include <kstd/memory.hpp>
+
 #include <cstddef>
 #include <string_view>
 #include <utility>
@@ -54,7 +56,7 @@ namespace kapi::boot_modules
     [[nodiscard]] auto module() const -> struct module const & override;
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
 
   private:
     struct module m_module;
diff --git a/kapi/kapi/devices.hpp b/kapi/kapi/devices.hpp
index c4bda9b9..c7de1830 100644
--- a/kapi/kapi/devices.hpp
+++ b/kapi/kapi/devices.hpp
@@ -58,8 +58,8 @@ namespace kapi::devices
   //! @param name A stable name for the device.
   //! @param implementation The implementation of the facet for the device.
   template<typename Facet>
-  [[nodiscard]] auto publish_facet(kstd::shared_ptr<device> device, kstd::string name, Facet * implementation)
-      -> kstd::result<void>
+  [[nodiscard]] auto publish_facet(kstd::shared_ptr<device> device, kstd::string name,
+                                   kstd::observer_ptr<Facet> implementation) -> kstd::result<void>
   {
     return facet_registry::get().publish(device, std::move(name), implementation);
   }
diff --git a/kapi/kapi/devices/bus.hpp b/kapi/kapi/devices/bus.hpp
index aaca462a..476216c7 100644
--- a/kapi/kapi/devices/bus.hpp
+++ b/kapi/kapi/devices/bus.hpp
@@ -59,7 +59,7 @@ namespace kapi::devices
 
   protected:
     //! All busses have the "bus" facet.
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
 
   private:
     auto do_remove_child(device & child) -> void;
diff --git a/kapi/kapi/devices/device.hpp b/kapi/kapi/devices/device.hpp
index 86566bff..c3a33daf 100644
--- a/kapi/kapi/devices/device.hpp
+++ b/kapi/kapi/devices/device.hpp
@@ -56,22 +56,22 @@ namespace kapi::devices
     //!
     //! @param id The id of the desired facet.
     //! @return An opaque pointer to the facet implementation if this device supports it, nullptr otherwise.
-    [[nodiscard]] auto facet(kapi::capabilities::facet_id id) noexcept -> void *;
+    [[nodiscard]] auto facet(kapi::capabilities::facet_id id) noexcept -> kstd::observer_ptr<void>;
 
     //! Get a specific facet of this device, if it supports it.
     //!
     //! @param id The id of the desired facet.
     //! @return A opaque pointer to the facet implementation if this device supports it, nullptr otherwise.
-    [[nodiscard]] auto facet(kapi::capabilities::facet_id id) const noexcept -> void const *;
+    [[nodiscard]] auto facet(kapi::capabilities::facet_id id) const noexcept -> kstd::observer_ptr<void const>;
 
     //! Get a specific facet of this device, if it supports it.
     //!
     //! @tparam FacetType The type of the desired facet.
     //! @return A typed pointer to the facet implementation if this device supports it, nullptr otherwise.
     template<typename FacetType>
-    [[nodiscard]] auto facet() -> FacetType *
+    [[nodiscard]] auto facet() -> kstd::observer_ptr<FacetType>
     {
-      return static_cast<FacetType *>(facet(FacetType::id));
+      return kstd::observer_ptr{static_cast<FacetType *>(facet(FacetType::id).get())};
     }
 
     //! Get a specific facet of this device, if it supports it.
@@ -79,9 +79,9 @@ namespace kapi::devices
     //! @tparam FacetType The type of the desired facet.
     //! @return A typed pointer to the facet implementation if this device supports it, nullptr otherwise.
     template<typename FacetType>
-    [[nodiscard]] auto facet() const noexcept -> FacetType const *
+    [[nodiscard]] auto facet() const noexcept -> kstd::observer_ptr<FacetType const>
     {
-      return static_cast<FacetType const *>(facet(FacetType::id));
+      return kstd::observer_ptr{static_cast<FacetType const *>(facet(FacetType::id).get())};
     }
 
     //! Check if this device has a specific facet.
@@ -119,7 +119,7 @@ namespace kapi::devices
     auto set_state(enum state state) -> void;
 
     //! Get the driver, if any, currently bound to this device.
-    [[nodiscard]] auto bound_driver() const noexcept -> driver *;
+    [[nodiscard]] auto bound_driver() const noexcept -> kstd::shared_ptr<driver>;
 
     //! Bind this device to the given driver.
     auto bind_driver(kstd::weak_ptr<struct driver> driver) -> void;
@@ -159,7 +159,7 @@ namespace kapi::devices
     auto set_resources(kstd::vector<resource> resources) -> void;
 
   protected:
-    auto virtual query_facet(kapi::capabilities::facet_id facet) -> void *;
+    auto virtual query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>;
 
   private:
     //! Busses need to be able to register themselves as a device's parent.
diff --git a/kapi/kapi/devices/driver.hpp b/kapi/kapi/devices/driver.hpp
index b46091fe..8c4d5e97 100644
--- a/kapi/kapi/devices/driver.hpp
+++ b/kapi/kapi/devices/driver.hpp
@@ -5,6 +5,7 @@
 
 #include <kapi/capabilities/facet_id.hpp>
 
+#include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 
 #include <cstdint>
@@ -66,9 +67,9 @@ namespace kapi::devices
     //! @return A pointer to this drivers implementation of the requested facet, nullptr if this driver does not
     //!         support the requested facet.
     template<typename FacetType>
-    [[nodiscard]] auto facet() -> FacetType *
+    [[nodiscard]] auto facet() -> kstd::observer_ptr<FacetType>
     {
-      return static_cast<FacetType *>(query_facet(FacetType::id));
+      return kstd::observer_ptr{static_cast<FacetType *>(query_facet(FacetType::id))};
     }
 
     //! Retrieve this drivers implementation of a given capability facet.
@@ -76,9 +77,10 @@ namespace kapi::devices
     //! @return A pointer to this drivers implementation of the requested facet, nullptr if this driver does not
     //!         support the requested facet.
     template<typename FacetType>
-    [[nodiscard]] auto facet() const -> FacetType const *
+    [[nodiscard]] auto facet() const -> kstd::observer_ptr<FacetType const>
     {
-      return static_cast<FacetType *>(const_cast<driver *>(this)->query_facet(FacetType::id));
+      return kstd::observer_ptr{
+        static_cast<FacetType const *>(const_cast<driver *>(this)->query_facet(FacetType::id).get())};
     }
 
     //! Check if this driver implements a given capability facet.
@@ -107,7 +109,7 @@ namespace kapi::devices
 
   protected:
     //! Return a pointer to the implementation of the given facet if this driver supports it.
-    virtual auto query_facet(kapi::capabilities::facet_id facet) -> void *;
+    virtual auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>;
   };
 
   //! @}
diff --git a/kapi/kapi/devices/facet_registry.hpp b/kapi/kapi/devices/facet_registry.hpp
index 3c405923..5e0367c1 100644
--- a/kapi/kapi/devices/facet_registry.hpp
+++ b/kapi/kapi/devices/facet_registry.hpp
@@ -51,7 +51,7 @@ namespace kapi::devices
       //! @param facet The id of the implemented facet.
       //! @param implementation A pointer to the actual implementation of the facet for the given device.
       constexpr entry(kstd::shared_ptr<struct device> device, kstd::string name, kapi::capabilities::facet_id facet,
-                      void * implementation)
+                      kstd::observer_ptr<void> implementation)
           : m_device{device}
           , m_name{name}
           , m_id{facet}
@@ -86,7 +86,7 @@ namespace kapi::devices
       //! Get the facet of the device-facet-implementation tuple described by this entry.
       //!
       //! @return An untyped pointer to the facet implementation.
-      [[nodiscard]] constexpr auto untyped_facet() const noexcept -> void *
+      [[nodiscard]] constexpr auto untyped_facet() const noexcept -> kstd::observer_ptr<void>
       {
         return m_facet;
       }
@@ -95,11 +95,11 @@ namespace kapi::devices
       //!
       //! @return A typed pointer to the facet if the facet id matches, nullptr otherwise.
       template<typename FacetType>
-      [[nodiscard]] constexpr auto facet() noexcept -> FacetType *
+      [[nodiscard]] constexpr auto facet() noexcept -> kstd::observer_ptr<FacetType>
       {
         if (m_id == FacetType::id)
         {
-          return static_cast<FacetType *>(untyped_facet());
+          return kstd::observer_ptr{static_cast<FacetType *>(untyped_facet().get())};
         }
         return nullptr;
       }
@@ -108,11 +108,11 @@ namespace kapi::devices
       //!
       //! @return A typed pointer to the facet if the facet id matches, nullptr otherwise.
       template<typename FacetType>
-      [[nodiscard]] constexpr auto facet() const noexcept -> FacetType const *
+      [[nodiscard]] constexpr auto facet() const noexcept -> kstd::observer_ptr<FacetType const>
       {
         if (m_id == FacetType::id)
         {
-          return static_cast<FacetType const *>(untyped_facet());
+          return kstd::observer_ptr{static_cast<FacetType const *>(untyped_facet().get())};
         }
         return nullptr;
       }
@@ -121,7 +121,7 @@ namespace kapi::devices
       kstd::weak_ptr<struct device> m_device;
       kstd::string m_name;
       kapi::capabilities::facet_id m_id;
-      void * m_facet;
+      kstd::observer_ptr<void> m_facet;
     };
 
     //! Construct an empty facet registry.
@@ -172,7 +172,7 @@ namespace kapi::devices
     //! @param name A stable name for the device.
     //! @param facet The implementation of the facet for the device.
     template<typename FacetType>
-    [[nodiscard]] auto publish(kstd::shared_ptr<device> device, kstd::string name, FacetType * facet)
+    [[nodiscard]] auto publish(kstd::shared_ptr<device> device, kstd::string name, kstd::observer_ptr<FacetType> facet)
         -> kstd::result<void>
     {
       return do_publish(device, std::move(name), FacetType::id, facet);
@@ -198,22 +198,22 @@ namespace kapi::devices
     //!
     //! @param id The id of the facet to look for.
     //! @param name The stable name of the device.
-    [[nodiscard]] auto resolve(kapi::capabilities::facet_id id, std::string_view name) -> void *;
+    [[nodiscard]] auto resolve(kapi::capabilities::facet_id id, std::string_view name) -> kstd::observer_ptr<void>;
 
     //! Attempt to resolve a facet for a device.
     //!
     //! @param id The id of the facet to look for.
     //! @param device The device.
-    [[nodiscard]] auto resolve(kapi::capabilities::facet_id id, device & device) -> void *;
+    [[nodiscard]] auto resolve(kapi::capabilities::facet_id id, device & device) -> kstd::observer_ptr<void>;
 
     //! Attempt to resolve a facet for a device by name.
     //!
     //! @tparam FacetType The facet to look for.
     //! @param name The stable name of the device.
     template<typename FacetType>
-    [[nodiscard]] auto resolve(std::string_view name) -> FacetType *
+    [[nodiscard]] auto resolve(std::string_view name) -> kstd::observer_ptr<FacetType>
     {
-      return static_cast<FacetType *>(resolve(FacetType::id, name));
+      return kstd::observer_ptr{static_cast<FacetType *>(resolve(FacetType::id, name).get())};
     }
 
     //! Attempt to resolve a facet for a device.
@@ -221,9 +221,9 @@ namespace kapi::devices
     //! @tparam FacetType The facet to look for.
     //! @param device The device.
     template<typename FacetType>
-    [[nodiscard]] auto resolve(device & device) -> FacetType *
+    [[nodiscard]] auto resolve(device & device) -> kstd::observer_ptr<FacetType>
     {
-      return static_cast<FacetType *>(resolve(FacetType::id, device));
+      return kstd::observer_ptr{static_cast<FacetType *>(resolve(FacetType::id, device).get())};
     }
 
     //! Subscribe to facet publish/withdraw notifications.
@@ -256,7 +256,7 @@ namespace kapi::devices
     //! @param id The id of the facet to be published for the device.
     //! @param facet The facet of the device.
     [[nodiscard]] auto do_publish(kstd::shared_ptr<device> device, kstd::string name, kapi::capabilities::facet_id id,
-                                  void * facet) -> kstd::result<void>;
+                                  kstd::observer_ptr<void> facet) -> kstd::result<void>;
 
     //! Notify all subscribed observers about a new facet having been published for a device.
     //!
diff --git a/kernel/kapi/boot_modules/device.cpp b/kernel/kapi/boot_modules/device.cpp
index dac24906..4bfce5f1 100644
--- a/kernel/kapi/boot_modules/device.cpp
+++ b/kernel/kapi/boot_modules/device.cpp
@@ -5,6 +5,7 @@
 #include <kapi/devices.hpp>
 
 #include <kstd/format.hpp>
+#include <kstd/memory.hpp>
 
 #include <cstddef>
 #include <string_view>
@@ -27,11 +28,11 @@ namespace kapi::boot_modules
     return m_module;
   }
 
-  auto device::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto device::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == boot_module_signature::id)
     {
-      return static_cast<boot_module_signature *>(this);
+      return kstd::make_observer<boot_module_signature>(this);
     }
 
     return kapi::devices::device::query_facet(facet);
diff --git a/kernel/kapi/devices/bus.cpp b/kernel/kapi/devices/bus.cpp
index 300151d5..d956c3b8 100644
--- a/kernel/kapi/devices/bus.cpp
+++ b/kernel/kapi/devices/bus.cpp
@@ -84,15 +84,15 @@ namespace kapi::devices
     return m_devices;
   }
 
-  auto bus::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto bus::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == bus::id)
     {
-      return this;
+      return kstd::observer_ptr(this);
     }
     else if (facet == bus_protocol::id)
     {
-      return m_protocol;
+      return kstd::observer_ptr{m_protocol};
     }
 
     return device::query_facet(facet);
diff --git a/kernel/kapi/devices/device.cpp b/kernel/kapi/devices/device.cpp
index 2576e20a..3a3b7cc1 100644
--- a/kernel/kapi/devices/device.cpp
+++ b/kernel/kapi/devices/device.cpp
@@ -23,12 +23,12 @@ namespace kapi::devices
       : m_name(name)
   {}
 
-  auto device::facet(kapi::capabilities::facet_id facet) noexcept -> void *
+  auto device::facet(kapi::capabilities::facet_id facet) noexcept -> kstd::observer_ptr<void>
   {
     return query_facet(facet);
   }
 
-  auto device::facet(kapi::capabilities::facet_id facet) const noexcept -> void const *
+  auto device::facet(kapi::capabilities::facet_id facet) const noexcept -> kstd::observer_ptr<void const>
   {
     return const_cast<device *>(this)->query_facet(facet);
   }
@@ -61,10 +61,10 @@ namespace kapi::devices
     m_state = state;
   }
 
-  auto device::bound_driver() const noexcept -> driver *
+  auto device::bound_driver() const noexcept -> kstd::shared_ptr<driver>
   {
     auto guard = kstd::lock_guard{m_lock};
-    return m_driver.lock().get();
+    return m_driver.lock();
   }
 
   auto device::bind_driver(kstd::weak_ptr<struct driver> driver) -> void
@@ -114,7 +114,7 @@ namespace kapi::devices
     m_resources = std::move(resources);
   }
 
-  auto device::query_facet(kapi::capabilities::facet_id) -> void *
+  auto device::query_facet(kapi::capabilities::facet_id) -> kstd::observer_ptr<void>
   {
     return nullptr;
   }
diff --git a/kernel/kapi/devices/driver.cpp b/kernel/kapi/devices/driver.cpp
index 5ca92dc8..0f103cbc 100644
--- a/kernel/kapi/devices/driver.cpp
+++ b/kernel/kapi/devices/driver.cpp
@@ -1,6 +1,7 @@
 #include <kapi/capabilities/facet_id.hpp>
 #include <kapi/devices.hpp>
 
+#include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 
 #include <cstdint>
@@ -29,7 +30,7 @@ namespace kapi::devices
     return kstd::success();
   }
 
-  auto driver::query_facet(kapi::capabilities::facet_id) -> void *
+  auto driver::query_facet(kapi::capabilities::facet_id) -> kstd::observer_ptr<void>
   {
     return nullptr;
   }
diff --git a/kernel/kapi/devices/driver.tests.cpp b/kernel/kapi/devices/driver.tests.cpp
index ee3fe577..38d07ed9 100644
--- a/kernel/kapi/devices/driver.tests.cpp
+++ b/kernel/kapi/devices/driver.tests.cpp
@@ -36,8 +36,8 @@ namespace
     [[nodiscard]] auto match(kapi::devices::device const & dev, kapi::devices::driver const & drv) const
         -> kstd::result<std::uint32_t> override
     {
-      auto const * signature = dev.facet<controller_signature>();
-      auto const * claim = drv.facet<controller_claim>();
+      auto const signature = dev.facet<controller_signature>();
+      auto const claim = drv.facet<controller_claim>();
       if (!signature || !claim || !std::ranges::contains(claim->supported_names(), signature->controller_name()))
       {
         return kstd::failure(kapi::devices::driver_match_errc::no_match);
@@ -65,11 +65,11 @@ namespace
     }
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override
     {
       if (facet == controller_signature::id)
       {
-        return static_cast<controller_signature *>(this);
+        return kstd::make_observer<controller_signature>(this);
       }
       return kapi::devices::bus::query_facet(facet);
     }
@@ -101,11 +101,11 @@ namespace
     }
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override
     {
       if (facet == leaf_signature::id)
       {
-        return static_cast<leaf_signature *>(this);
+        return kstd::make_observer<leaf_signature>(this);
       }
       return kapi::devices::device::query_facet(facet);
     }
@@ -123,9 +123,9 @@ namespace
     [[nodiscard]] auto match(kapi::devices::device const & dev, kapi::devices::driver const & drv) const
         -> kstd::result<std::uint32_t> override
     {
-      auto const * ident = dev.facet<leaf_signature>();
-      auto const * claims = drv.facet<leaf_claim>();
-      if (!ident || !claims || !std::ranges::contains(claims->supported_names(), ident->leaf_name()))
+      auto const signature = dev.facet<leaf_signature>();
+      auto const claims = drv.facet<leaf_claim>();
+      if (!signature || !claims || !std::ranges::contains(claims->supported_names(), signature->leaf_name()))
       {
         return kstd::failure(kapi::devices::driver_match_errc::no_match);
       }
@@ -166,11 +166,11 @@ namespace
     }
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override
     {
       if (facet == controller_claim::id)
       {
-        return static_cast<controller_claim *>(this);
+        return kstd::make_observer<controller_claim>(this);
       }
 
       return kapi::devices::driver::query_facet(facet);
@@ -198,11 +198,11 @@ namespace
     }
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override
     {
       if (facet == leaf_claim::id)
       {
-        return static_cast<leaf_claim *>(this);
+        return kstd::make_observer<leaf_claim>(this);
       }
 
       return kapi::devices::driver::query_facet(facet);
@@ -213,7 +213,8 @@ namespace
 SCENARIO("a bound controller driver can attach a further, independently-typed bus protocol of its own",
          "[devices][driver][stacking]")
 {
-  GIVEN("a controller bus, a controller driver, and a leaf driver, none aware of each other's identification scheme")
+  GIVEN(
+      "a controller bus, a controller driver, and a leaf driver, none aware of each other's signatureification scheme")
   {
     auto outer_bus = kstd::make_shared<controller_bus>("stacking_test_controller_bus");
 
diff --git a/kernel/kapi/devices/driver_registry.tests.cpp b/kernel/kapi/devices/driver_registry.tests.cpp
index 02f5065f..7b08799c 100644
--- a/kernel/kapi/devices/driver_registry.tests.cpp
+++ b/kernel/kapi/devices/driver_registry.tests.cpp
@@ -40,7 +40,7 @@ namespace
     {
       ++*match_calls;
 
-      auto const * identification = driver.facet<test_claim>();
+      auto const identification = driver.facet<test_claim>();
       if (!identification)
       {
         return kstd::failure(kapi::devices::driver_match_errc::no_match);
@@ -107,11 +107,11 @@ namespace
     mutable unsigned probe_calls;
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override
     {
       if (facet == test_claim::id)
       {
-        return static_cast<test_claim *>(this);
+        return kstd::make_observer<test_claim>(this);
       }
 
       return kapi::devices::driver::query_facet(facet);
@@ -178,7 +178,7 @@ SCENARIO("Driver registry picks the highest-priority match", "[devices][driver_r
       {
         auto dev = kapi::devices::device_registry::get().find("driver_registry_priority_device");
         REQUIRE(dev != nullptr);
-        REQUIRE(dev->bound_driver() == high_priority.get());
+        REQUIRE(dev->bound_driver() == high_priority);
       }
     }
   }
@@ -203,7 +203,7 @@ SCENARIO("Driver registry breaks ties by registration order", "[devices][driver_
       {
         auto dev = kapi::devices::device_registry::get().find("driver_registry_tie_device");
         REQUIRE(dev != nullptr);
-        REQUIRE(dev->bound_driver() == registered_first.get());
+        REQUIRE(dev->bound_driver() == registered_first);
       }
     }
   }
@@ -255,7 +255,7 @@ SCENARIO("Driver registry leaves bound driver bound, even if better driver arriv
           auto dev = kapi::devices::device_registry::get().find("driver_probe_failure_device");
           REQUIRE(dev != nullptr);
           REQUIRE(dev->state() == kapi::devices::state::bound);
-          REQUIRE(dev->bound_driver() == lower.get());
+          REQUIRE(dev->bound_driver() == lower);
         }
       }
     }
diff --git a/kernel/kapi/devices/facet_registry.cpp b/kernel/kapi/devices/facet_registry.cpp
index 2974c71e..f2f5d03b 100644
--- a/kernel/kapi/devices/facet_registry.cpp
+++ b/kernel/kapi/devices/facet_registry.cpp
@@ -46,7 +46,7 @@ namespace kapi::devices
   }
 
   auto facet_registry::do_publish(kstd::shared_ptr<device> device, kstd::string name, kapi::capabilities::facet_id id,
-                                  void * facet) -> kstd::result<void>
+                                  kstd::observer_ptr<void> facet) -> kstd::result<void>
   {
     auto published = std::optional<entry>{};
 
@@ -169,7 +169,7 @@ namespace kapi::devices
     return filtered;
   }
 
-  auto facet_registry::resolve(kapi::capabilities::facet_id facet, std::string_view name) -> void *
+  auto facet_registry::resolve(kapi::capabilities::facet_id facet, std::string_view name) -> kstd::observer_ptr<void>
   {
     auto found_device = kstd::shared_ptr<device>{};
     {
@@ -193,7 +193,7 @@ namespace kapi::devices
     return resolve(facet, *found_device);
   }
 
-  auto facet_registry::resolve(kapi::capabilities::facet_id id, device & device) -> void *
+  auto facet_registry::resolve(kapi::capabilities::facet_id id, device & device) -> kstd::observer_ptr<void>
   {
     if (auto by_device = device.facet(id))
     {
diff --git a/kernel/kapi/devices/facet_registry.tests.cpp b/kernel/kapi/devices/facet_registry.tests.cpp
index 9396fc6c..f6735f01 100644
--- a/kernel/kapi/devices/facet_registry.tests.cpp
+++ b/kernel/kapi/devices/facet_registry.tests.cpp
@@ -50,15 +50,15 @@ namespace
       return m_value;
     }
 
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override
     {
       if (facet == probe_device::id)
       {
-        return static_cast<probe_device *>(this);
+        return kstd::make_observer<probe_device>(this);
       }
       if (facet == const_device::id)
       {
-        return m_const_device;
+        return kstd::observer_ptr{m_const_device};
       }
 
       return kapi::devices::device::query_facet(facet);
@@ -143,7 +143,7 @@ SCENARIO("Publishing and finding a device", "[kapi][devices][facet_registry]")
 
       THEN("publishing a free standing second facet for the same device succeeds")
       {
-        REQUIRE(registry.publish(device, "probe0", &free_standing_facet));
+        REQUIRE(registry.publish(device, "probe0", kstd::make_observer(&free_standing_facet)));
       }
 
       AND_WHEN("getting all devices implementing that facet")
@@ -239,7 +239,7 @@ SCENARIO("Publishing and finding a device", "[kapi][devices][facet_registry]")
 
     THEN("publishing the facet for the device fails")
     {
-      REQUIRE_FALSE(registry.publish(device, "probe0", &facet));
+      REQUIRE_FALSE(registry.publish(device, "probe0", kstd::make_observer(&facet)));
     }
   }
 }
diff --git a/kernel/kernel/devices/pseudo.cpp b/kernel/kernel/devices/pseudo.cpp
index 13a8be3d..f5ee13c3 100644
--- a/kernel/kernel/devices/pseudo.cpp
+++ b/kernel/kernel/devices/pseudo.cpp
@@ -5,6 +5,7 @@
 #include <kapi/capabilities/facet_id.hpp>
 #include <kapi/devices.hpp>
 
+#include <kstd/memory.hpp>
 #include <kstd/string.hpp>
 
 #include <utility>
@@ -16,11 +17,11 @@ namespace kernel::devices
       : kapi::devices::device{std::move(name)}
   {}
 
-  auto pseudo::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto pseudo::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == kernel::bus::pseudo_signature::id)
     {
-      return &m_signature;
+      return kstd::make_observer(&m_signature);
     }
 
     return device::query_facet(facet);
diff --git a/kernel/kernel/devices/pseudo.hpp b/kernel/kernel/devices/pseudo.hpp
index efd504d5..eabe59b0 100644
--- a/kernel/kernel/devices/pseudo.hpp
+++ b/kernel/kernel/devices/pseudo.hpp
@@ -6,6 +6,7 @@
 #include <kapi/capabilities/facet_id.hpp>
 #include <kapi/devices.hpp>
 
+#include <kstd/memory.hpp>
 #include <kstd/string.hpp>
 
 #include <string_view>
@@ -33,7 +34,7 @@ namespace kernel::devices
     explicit pseudo(kstd::string name);
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
 
   private:
     pseudo_signature m_signature{*this};
diff --git a/kernel/kernel/drivers/pseudo/null.cpp b/kernel/kernel/drivers/pseudo/null.cpp
index 4c8bde12..9d8330b1 100644
--- a/kernel/kernel/drivers/pseudo/null.cpp
+++ b/kernel/kernel/drivers/pseudo/null.cpp
@@ -76,7 +76,7 @@ namespace kernel::drivers::pseudo
 
     auto implementation = kstd::make_shared<null_node>();
     auto published = kapi::devices::publish_facet<kapi::filesystem::character_special_file>(
-        device.shared_from_this(), "null", implementation.get());
+        device.shared_from_this(), "null", kstd::make_observer(implementation.get()));
 
     if (!published)
     {
@@ -117,11 +117,11 @@ namespace kernel::drivers::pseudo
     return names;
   }
 
-  auto null::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto null::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == kernel::bus::pseudo_claim::id)
     {
-      return static_cast<kernel::bus::pseudo_claim *>(this);
+      return kstd::make_observer<kernel::bus::pseudo_claim>(this);
     }
 
     return kapi::devices::driver::query_facet(facet);
diff --git a/kernel/kernel/drivers/pseudo/null.hpp b/kernel/kernel/drivers/pseudo/null.hpp
index 6a736c33..ab8affeb 100644
--- a/kernel/kernel/drivers/pseudo/null.hpp
+++ b/kernel/kernel/drivers/pseudo/null.hpp
@@ -6,6 +6,7 @@
 #include <kapi/devices.hpp>
 #include <kapi/filesystem.hpp>
 
+#include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 
 #include <cstdint>
@@ -36,7 +37,7 @@ namespace kernel::drivers::pseudo
     [[nodiscard]] auto supported_names() const noexcept -> std::span<std::string_view const> override;
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
   };
 
 }  // namespace kernel::drivers::pseudo
diff --git a/kernel/kernel/drivers/pseudo/zero.cpp b/kernel/kernel/drivers/pseudo/zero.cpp
index 67ec2519..fda28d35 100644
--- a/kernel/kernel/drivers/pseudo/zero.cpp
+++ b/kernel/kernel/drivers/pseudo/zero.cpp
@@ -77,7 +77,7 @@ namespace kernel::drivers::pseudo
 
     auto implementation = kstd::make_shared<zero_node>();
     auto published = kapi::devices::publish_facet<kapi::filesystem::character_special_file>(
-        device.shared_from_this(), "zero", implementation.get());
+        device.shared_from_this(), "zero", kstd::make_observer(implementation.get()));
 
     if (!published)
     {
@@ -118,11 +118,11 @@ namespace kernel::drivers::pseudo
     return names;
   }
 
-  auto zero::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto zero::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == kernel::bus::pseudo_claim::id)
     {
-      return static_cast<kernel::bus::pseudo_claim *>(this);
+      return kstd::make_observer<kernel::bus::pseudo_claim>(this);
     }
 
     return kapi::devices::driver::query_facet(facet);
diff --git a/kernel/kernel/drivers/pseudo/zero.hpp b/kernel/kernel/drivers/pseudo/zero.hpp
index 7f26cc41..b5573e58 100644
--- a/kernel/kernel/drivers/pseudo/zero.hpp
+++ b/kernel/kernel/drivers/pseudo/zero.hpp
@@ -6,6 +6,7 @@
 #include <kapi/devices.hpp>
 #include <kapi/filesystem.hpp>
 
+#include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 
 #include <cstdint>
@@ -31,7 +32,7 @@ namespace kernel::drivers::pseudo
     [[nodiscard]] auto supported_names() const noexcept -> std::span<std::string_view const> override;
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
   };
 
 }  // namespace kernel::drivers::pseudo
diff --git a/kernel/kernel/drivers/storage/ram_disk.cpp b/kernel/kernel/drivers/storage/ram_disk.cpp
index 80f7eedc..d33b7312 100644
--- a/kernel/kernel/drivers/storage/ram_disk.cpp
+++ b/kernel/kernel/drivers/storage/ram_disk.cpp
@@ -118,12 +118,12 @@ namespace kernel::drivers::storage
         std::ranges::count_if(kapi::devices::facet_registry::get().all(kapi::filesystem::block_special_file::id),
                               [this](auto const & published) {
                                 auto published_device = published.device();
-                                return published_device && published_device->bound_driver() == this;
+                                return published_device && published_device->bound_driver().get() == this;
                               });
     auto name = kstd::format("ram{}", next_index);
 
-    auto published = kapi::devices::publish_facet<kapi::filesystem::block_special_file>(device.shared_from_this(), name,
-                                                                                        implementation.get());
+    auto published = kapi::devices::publish_facet<kapi::filesystem::block_special_file>(
+        device.shared_from_this(), name, kstd::make_observer(implementation.get()));
     if (!published)
     {
       return published;
@@ -155,11 +155,11 @@ namespace kernel::drivers::storage
     return "Generic RAM Disk";
   }
 
-  auto ram_disk::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto ram_disk::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == kapi::boot_modules::boot_module_claim::id)
     {
-      return static_cast<kapi::boot_modules::boot_module_claim *>(this);
+      return kstd::make_observer<kapi::boot_modules::boot_module_claim>(this);
     }
 
     return kapi::devices::driver::query_facet(facet);
diff --git a/kernel/kernel/drivers/storage/ram_disk.hpp b/kernel/kernel/drivers/storage/ram_disk.hpp
index a526435b..1f7d5774 100644
--- a/kernel/kernel/drivers/storage/ram_disk.hpp
+++ b/kernel/kernel/drivers/storage/ram_disk.hpp
@@ -5,6 +5,7 @@
 #include <kapi/capabilities/facet_id.hpp>
 #include <kapi/devices.hpp>
 
+#include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 
 #include <cstdint>
@@ -28,7 +29,7 @@ namespace kernel::drivers::storage
     [[nodiscard]] auto name() const noexcept -> std::string_view override;
 
   protected:
-    auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
   };
 
 }  // namespace kernel::drivers::storage
diff --git a/kernel/kernel/test_support/devices/block_device.cpp b/kernel/kernel/test_support/devices/block_device.cpp
index 462dc79d..fa834122 100644
--- a/kernel/kernel/test_support/devices/block_device.cpp
+++ b/kernel/kernel/test_support/devices/block_device.cpp
@@ -3,6 +3,7 @@
 #include <kapi/devices.hpp>
 #include <kapi/filesystem.hpp>
 
+#include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 #include <kstd/string.hpp>
 #include <kstd/units.hpp>
@@ -68,11 +69,11 @@ namespace kernel::tests::devices
     return kstd::bytes{data.size()};
   }
 
-  auto block_device::query_facet(kapi::capabilities::facet_id facet) -> void *
+  auto block_device::query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void>
   {
     if (facet == kapi::filesystem::block_special_file::id)
     {
-      return static_cast<kapi::filesystem::block_special_file *>(this);
+      return kstd::make_observer<kapi::filesystem::block_special_file>(this);
     }
 
     return kapi::devices::device::query_facet(facet);
diff --git a/kernel/kernel/test_support/devices/block_device.hpp b/kernel/kernel/test_support/devices/block_device.hpp
index 9e64ed18..94c9a58d 100644
--- a/kernel/kernel/test_support/devices/block_device.hpp
+++ b/kernel/kernel/test_support/devices/block_device.hpp
@@ -4,6 +4,7 @@
 #include <kapi/devices.hpp>
 #include <kapi/filesystem.hpp>
 
+#include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 #include <kstd/string.hpp>
 #include <kstd/units.hpp>
@@ -29,7 +30,7 @@ namespace kernel::tests::devices
     kstd::vector<std::uint8_t> data{};
 
   private:
-    [[nodiscard]] auto query_facet(kapi::capabilities::facet_id facet) -> void * override;
+    [[nodiscard]] auto query_facet(kapi::capabilities::facet_id facet) -> kstd::observer_ptr<void> override;
 
     kstd::bytes m_block_size{};
   };
diff --git a/kernel/kernel/vfs/device_inode.cpp b/kernel/kernel/vfs/device_inode.cpp
index e9c70f15..75ed03d6 100644
--- a/kernel/kernel/vfs/device_inode.cpp
+++ b/kernel/kernel/vfs/device_inode.cpp
@@ -89,12 +89,12 @@ namespace kernel::vfs
 
   auto device_inode::is_block_device() const -> bool
   {
-    return kapi::devices::facet_registry::get().resolve<kapi::filesystem::block_special_file>(*m_device);
+    return !!kapi::devices::facet_registry::get().resolve<kapi::filesystem::block_special_file>(*m_device);
   }
 
   auto device_inode::is_character_device() const -> bool
   {
-    return kapi::devices::facet_registry::get().resolve<kapi::filesystem::character_special_file>(*m_device);
+    return !!kapi::devices::facet_registry::get().resolve<kapi::filesystem::character_special_file>(*m_device);
   }
 
   auto device_inode::status() const -> kstd::result<kapi::filesystem::file_status>