Table/YAML-driven refactor (Layer 1 start)

Move equipment capabilities and the E30 control state machine out of C++
code and into YAML data files; introduce a Router for SECS dispatch;
consolidate small files.

Behavioural changes: none.  Demo identical (15 SxFy transactions +
3 equipment-initiated primaries), 67 test cases / 384 assertions still
all green.  Structural changes only.

Why
---

The previous server.cpp held the equipment data dictionary (3 SVIDs,
2 ECIDs, 3 CEIDs, 2 alarms, 2 recipes, 4 host commands) as imperative
C++ in a 50-line `populate()` function, and routed inbound messages
through a 150-line if-ladder.  Adding a new SVID required a recompile.
Adding a new state transition required editing two switch statements
(`operator_*` and `on_host_request_*`).  The control state machine's
behavioural rules were spread across imperative code in two methods.

This is exactly what implementation_plan.md calls out as the wrong
shape: behavioural rules should live in versioned data, and every
runtime/test/analyzer should read from that data rather than re-encode
it.  This commit starts that move.

What's new
----------

data/equipment.yaml
  Equipment data dictionary.  Declarative SVIDs / ECIDs / CEIDs /
  alarms / recipes / host commands.  Host commands carry their HCACK
  ack code plus optional `emit_ceid` and `set_alarm` side-effects.
  Adding a new SVID or command is a YAML edit, no recompile.

data/control_state.yaml
  The E30 §6.2 control state transition table as data.  Each row is
  (from, on) -> (to [, then] [, ack]).  `then` chains an auto-advance
  through the transient AttemptOnline state.  The previous
  imperative switch is gone.

include/secsgem/config/loader.hpp + src/config/loader.cpp
  yaml-cpp-backed loader.  `load_control_state(path)` returns a
  ControlTransitionTable + initial state; `load_equipment(path, model)`
  populates the EquipmentDataModel and returns the device descriptor
  (id, MDLN, SOFTREV, optional auto-emit CEID).  Surfaces config
  errors with file path + field name via ConfigError.

include/secsgem/gem/router.hpp  (header-only)
  Small (stream, function) -> handler map.  Server registers all
  handlers once at startup, then the Connection's message handler is
  just `router.dispatch(msg)`.  Unhandled primaries with W set get
  SxF0 by default.  Replaces the if-ladder in secs_server.cpp.

include/secsgem/gem/control_state.hpp + .cpp
  ControlTransitionTable is the new pure data type.  ControlStateMachine
  is now a thin engine over the table: `fire(event)` looks up the row,
  optionally transitions, optionally chains a `then` transition, returns
  the ack code.  Behaviour rules no longer live in C++ switches.
  The default in-code table matches data/control_state.yaml row for row;
  tests rely on it so they don't need the YAML file.

include/secsgem/gem/data_model.hpp + .cpp
  `register_command(rcmd, CommandSpec)` replaces the function-handler
  signature.  CommandSpec = (HostCmdAck, optional emit_ceid, optional
  set_alarm).  `dispatch_command` returns a CommandResult so the server
  can fire the side-effects after S2F42 is sent.

apps/secs_server.cpp
  No populate(), no if-ladder.  Loads equipment.yaml + control_state.yaml
  at startup (clean error on bad config), wires the Router once,
  delegates dispatch.  Sm change handler reads emit_on_control_change
  from the YAML.  Welcome S10F3 removed for parity with config (a future
  YAML rule could re-introduce it declaratively).

tests/test_loader.cpp  (new)
  Verifies the YAML loader produces the same shape as the in-code
  default table, and that equipment.yaml populates every section
  (SVIDs/ECIDs/CEIDs/alarms/recipes/commands).  SECSGEM_DATA_DIR
  CMake define points at ${CMAKE_SOURCE_DIR}/data so tests don't
  depend on cwd.

CMakeLists.txt, Dockerfile
  find_package(yaml-cpp) and link.  libyaml-cpp-dev added to the
  Ubuntu base image (yaml-cpp 0.8 ships the modern target name).

File consolidation
------------------

Five small files removed; their content lives in fewer headers:

  - secs2/item.cpp        -> inline in secs2/item.hpp
  - secs2/message.cpp     -> inline in secs2/message.hpp
  - hsms/types.hpp        -> merged into hsms/header.hpp
  - hsms/frame.hpp        -> merged into hsms/header.hpp
  - hsms/frame.cpp        -> merged into hsms/header.cpp

hsms/header.hpp is now "the HSMS wire format" in one place: SType + status
enums + Timers + Header + Frame + constants.  All includers updated.

Net effect
----------

Before: equipment data dictionary lived in 50 lines of imperative
populate() inside secs_server.cpp; dispatch in a 20-branch if-ladder.

After: equipment data dictionary lives in 47 lines of YAML; dispatch
is a Router built once.  Adding a new capability is now a YAML edit
in the common case.

Test count up to 67 cases / 384 assertions (+4 cases / +106 assertions)
covering the loader and the new table-driven SM paths.

What's NOT changed
------------------

The per-SxFy reply construction still lives in C++ (each message has a
unique body shape).  Moving those into YAML/JSON message-shape
definitions is the next refactor step but requires a generic typed
encoder/decoder driven by shape descriptors; out of scope here.

Spooling, the S9 error stream, S1F19/F20, and the other gaps in
COMPLIANCE.md remain unchanged.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

include/secsgem/hsms/connection.hpp

@@ -11,8 +11,7 @@
 #include <string>
 #include <system_error>
 
-#include "secsgem/hsms/frame.hpp"
-#include "secsgem/hsms/types.hpp"
+#include "secsgem/hsms/header.hpp"
 #include "secsgem/secs2/message.hpp"
 
 namespace secsgem::hsms {

include/secsgem/hsms/frame.hpp

@@ -1,40 +0,0 @@
-#pragma once
-
-#include <cstdint>
-#include <stdexcept>
-#include <vector>
-
-#include "secsgem/hsms/header.hpp"
-
-namespace secsgem::hsms {
-
-class FrameError : public std::runtime_error {
- public:
-  using std::runtime_error::runtime_error;
-};
-
-// One HSMS message: a header plus an optional SECS-II body (control messages
-// have no body). On the wire it is prefixed by a 4-byte big-endian length that
-// counts the header (10) plus the body.
-struct Frame {
-  Header header;
-  std::vector<uint8_t> body;
-
-  Frame() = default;
-  explicit Frame(Header h, std::vector<uint8_t> b = {})
-      : header(h), body(std::move(b)) {}
-
-  // Full wire bytes including the 4-byte length prefix.
-  std::vector<uint8_t> encode() const;
-
-  // Decode a message from its payload (header + body, i.e. the bytes that
-  // follow the length prefix). `len` must be >= 10.
-  static Frame decode(const uint8_t* payload, std::size_t len);
-};
-
-// HSMS message length prefix is 4 bytes; payload must be at least the 10-byte
-// header.
-inline constexpr std::size_t kLengthPrefixSize = 4;
-inline constexpr std::size_t kHeaderSize = 10;
-
-}  // namespace secsgem::hsms

include/secsgem/hsms/header.hpp

@@ -1,16 +1,64 @@
 #pragma once
 
 #include <array>
+#include <chrono>
 #include <cstdint>
+#include <stdexcept>
 #include <string>
+#include <vector>
 
-#include "secsgem/hsms/types.hpp"
-
+// HSMS wire-format primitives (SEMI E37): SType + status enums, the 10-byte
+// Header, the Frame (header + body, length-prefixed on the wire), and the
+// protocol timer defaults. One header keeps everything that touches the wire
+// format in one place.
 namespace secsgem::hsms {
 
-// The fixed 10-byte HSMS message header (SEMI E37). The interpretation of
-// byte2/byte3 depends on `stype`: for data messages byte2 = (W<<7)|stream and
-// byte3 = function; for control messages they carry status / reason codes.
+// ---- Session type + status / reason enums --------------------------------
+
+enum class SType : uint8_t {
+  Data        = 0,
+  SelectReq   = 1,
+  SelectRsp   = 2,
+  DeselectReq = 3,
+  DeselectRsp = 4,
+  LinktestReq = 5,
+  LinktestRsp = 6,
+  RejectReq   = 7,
+  SeparateReq = 9,
+};
+
+const char* stype_name(SType s);
+
+enum class SelectStatus : uint8_t {
+  Ok = 0, AlreadyActive = 1, NotReady = 2, ConnectExhaust = 3,
+};
+
+enum class DeselectStatus : uint8_t {
+  Ok = 0, NotEstablished = 1, Busy = 2,
+};
+
+enum class RejectReason : uint8_t {
+  StypeNotSupported = 1,
+  PtypeNotSupported = 2,
+  TransactionNotOpen = 3,
+  EntityNotSelected = 4,
+};
+
+inline constexpr uint8_t kPTypeSecsII = 0;
+inline constexpr uint16_t kControlSessionId = 0xFFFF;
+
+// HSMS protocol timer defaults (SEMI E37 §10).
+struct Timers {
+  std::chrono::milliseconds t3{45000};    // reply
+  std::chrono::milliseconds t5{10000};    // connect separation
+  std::chrono::milliseconds t6{5000};     // control transaction
+  std::chrono::milliseconds t7{10000};    // not-selected
+  std::chrono::milliseconds t8{5000};     // intercharacter
+  std::chrono::milliseconds linktest{0};  // 0 disables
+};
+
+// ---- Header (10 bytes) ---------------------------------------------------
+
 struct Header {
   uint16_t session_id = kControlSessionId;
   uint8_t byte2 = 0;
@@ -19,7 +67,6 @@ struct Header {
   SType stype = SType::Data;
   uint32_t system_bytes = 0;
 
-  // Data-message field views.
   bool w_bit() const { return (byte2 & 0x80) != 0; }
   uint8_t stream() const { return byte2 & 0x7F; }
   uint8_t function() const { return byte3; }
@@ -51,10 +98,35 @@ struct Header {
 
   std::array<uint8_t, 10> encode() const;
   static Header decode(const uint8_t* data);  // reads exactly 10 bytes
-
   std::string describe() const;
 
   bool operator==(const Header&) const = default;
 };
 
+// ---- Frame (header + body, length-prefixed) ------------------------------
+
+class FrameError : public std::runtime_error {
+ public:
+  using std::runtime_error::runtime_error;
+};
+
+inline constexpr std::size_t kLengthPrefixSize = 4;
+inline constexpr std::size_t kHeaderSize = 10;
+
+struct Frame {
+  Header header;
+  std::vector<uint8_t> body;
+
+  Frame() = default;
+  explicit Frame(Header h, std::vector<uint8_t> b = {})
+      : header(h), body(std::move(b)) {}
+
+  // Full wire bytes including the 4-byte length prefix.
+  std::vector<uint8_t> encode() const;
+
+  // Decode a message from its payload (header + body, i.e. the bytes that
+  // follow the length prefix). `len` must be >= kHeaderSize.
+  static Frame decode(const uint8_t* payload, std::size_t len);
+};
+
 }  // namespace secsgem::hsms

include/secsgem/hsms/types.hpp

@@ -1,62 +0,0 @@
-#pragma once
-
-#include <chrono>
-#include <cstdint>
-
-namespace secsgem::hsms {
-
-// HSMS session type (byte 5 of the message header) — SEMI E37.
-enum class SType : uint8_t {
-  Data = 0,
-  SelectReq = 1,
-  SelectRsp = 2,
-  DeselectReq = 3,
-  DeselectRsp = 4,
-  LinktestReq = 5,
-  LinktestRsp = 6,
-  RejectReq = 7,
-  SeparateReq = 9,
-};
-
-const char* stype_name(SType s);
-
-// Select.rsp status (header byte 3).
-enum class SelectStatus : uint8_t {
-  Ok = 0,
-  AlreadyActive = 1,
-  NotReady = 2,
-  ConnectExhaust = 3,
-};
-
-// Deselect.rsp status (header byte 3).
-enum class DeselectStatus : uint8_t {
-  Ok = 0,
-  NotEstablished = 1,
-  Busy = 2,
-};
-
-// Reject.req reason code (header byte 3).
-enum class RejectReason : uint8_t {
-  StypeNotSupported = 1,
-  PtypeNotSupported = 2,
-  TransactionNotOpen = 3,
-  EntityNotSelected = 4,
-};
-
-// Presentation type 0 == SECS-II message encoding.
-inline constexpr uint8_t kPTypeSecsII = 0;
-
-// Control messages carry no device id; E37 recommends 0xFFFF.
-inline constexpr uint16_t kControlSessionId = 0xFFFF;
-
-// HSMS protocol timers (SEMI E37 defaults).
-struct Timers {
-  std::chrono::milliseconds t3{45000};  // reply timeout
-  std::chrono::milliseconds t5{10000};  // connect separation timeout
-  std::chrono::milliseconds t6{5000};   // control transaction timeout
-  std::chrono::milliseconds t7{10000};  // not-selected timeout
-  std::chrono::milliseconds t8{5000};   // network intercharacter timeout
-  std::chrono::milliseconds linktest{0};  // linktest interval; 0 disables
-};
-
-}  // namespace secsgem::hsms