feat: EquipmentRuntime engine owner + secs_gemd gRPC daemon

Extract the SECS/GEM engine wiring out of the secs_server app into a
reusable class, and stand up a language-agnostic gRPC daemon on top so a
tool's software (any language) can drive the equipment without linking C++
or knowing SEMI. Foundation for replacing a vendor's SECS/GEM server.

Engine reuse:
- EquipmentRuntime (include/secsgem/gem/runtime.hpp, src/gem/runtime.cpp):
  owns io_context, passive Server, model, control-state machine, Router;
  thread-safe outbound API (set_variable/emit_event/set_alarm/clear_alarm),
  on_command hook, deliver_or_spool, run()/run_async()/poll()/stop().
- register_default_handlers (src/gem/default_handlers.cpp): the 56 GEM
  handlers + domain emitters, relocated from secs_server so the app and the
  daemon speak byte-identical GEM. secs_server.cpp reduced ~1270 -> 113 lines.
- name_index.hpp: resolve_variable(name) -> VID (the name->id binding layer).

Daemon (apps/secs_gemd.cpp, proto/secsgem/v1/equipment.proto):
- runs the engine + HSMS link on a background thread; serves the gRPC
  Equipment service. Increment 1: SetVariables (name-resolved, plain
  value->Item) and GetControlState. proto carries the full v1 surface
  (universal + carrier/recipe/job tiers); remaining RPCs + the Subscribe
  command stream are next (docs/DAEMON_ROADMAP.md).
- CMake: opt-in SECSGEM_DAEMON, protoc/grpc_cpp_plugin codegen, gracefully
  skipped where protobuf/grpc++ are absent. Dockerfile gains the grpc deps.

Tests (proof): test_runtime, test_default_handlers (S1F1->S1F2, S2F41->hook),
test_name_index. Full suite 458/458, 2795 assertions; live server<->client
GEM300 demo still passes on the refactored server.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/DAEMON_ROADMAP.md

@@ -0,0 +1,94 @@
+# Vendor Daemon & gRPC API — Status and Roadmap to Fab-Readiness
+
+> **This is a forward-looking roadmap, not a description of shipped behaviour.**
+> Every item carries a status marker. Do not read an item as "done" unless it
+> says ✅. (Written 2026-06-10.)
+>
+> Status legend: ✅ done · 🚧 in progress · ⬜ planned · ⚠️ risk/unknown
+
+## What this is
+
+A vendor-facing **daemon** that runs the SECS/GEM engine as its own process and
+exposes a small, name-based, language-agnostic API over gRPC, so a tool's
+control software (in any language) can drive the equipment without linking C++
+or knowing SEMI. See `proto/secsgem/v1/equipment.proto` for the API.
+
+The point of the daemon model: it owns the durable HSMS relationship with the
+host and stays conformant while the tool software restarts/upgrades/crashes.
+
+## Current status (2026-06-10)
+
+| Piece | Status | Notes |
+|---|---|---|
+| `proto/secsgem/v1/equipment.proto` | ✅ | v1 API surface designed (universal + carrier/recipe/job tiers) |
+| `HostCommandRegistry::set_handler` behaviour hook | ✅ | the engine seam the daemon binds to; tested |
+| `EquipmentRuntime` (engine owner) | ✅ | infra + outbound API built & tested (`tests/test_runtime.cpp`); **`secs_server` now runs entirely on it** (verified by the live server↔client GEM300 demo — full job/spool/control-state flow, client exit 0). |
+| `register_default_handlers` in the library (so the daemon reuses the 56 handlers) | ✅ | relocated into `src/gem/default_handlers.cpp` (programmatic move, zero retype); `secs_server` reduced to ~113 lines and calls it. Tested (`tests/test_default_handlers.cpp`: S1F1→S1F2, S2F41→on_command hook) + live GEM300 demo still passes. |
+| gRPC/protobuf in toolchain (Dockerfile + CMake) | 🚧 | apt deps added to Dockerfile (`libgrpc++-dev libprotobuf-dev protobuf-compiler-grpc`); **image rebuild + CMake proto codegen still TODO**. |
+| `secs_gemd` daemon implementing the service | ⬜ | translate RPCs ↔ runtime; stream host requests |
+| Reference client library (Python) | ⬜ | thin wrapper over generated stubs |
+
+**Nothing in the proto is wired to the engine yet.** The engine itself is broad
+(56 wire handlers across S1/2/3/5/6/7/10/14/16; all GEM300 stores) — the daemon
+is about *exposing* that, not building it.
+
+## Gaps to fab-readiness
+
+### Layer 0 — Make it run at all (blocks everything)
+- ⬜ Extract `EquipmentRuntime` from `apps/secs_server.cpp` (io_context, Server,
+  model, router, emit lambdas, `set_handler`). Reduce `secs_server` to a thin
+  `main()` over it. Verify against the existing test suite.
+- ⬜ Add gRPC/protobuf to the Dockerfile + CMake codegen for the proto.
+- ⬜ Implement `secs_gemd`: construct the runtime, `io.run()` on a background
+  thread, map each RPC to a runtime call, route host requests onto the
+  `Subscribe` stream via `set_handler` + the FSM change handlers.
+- ⬜ One reference client (Python) proving the end-to-end loop.
+
+### Layer 1 — API completeness (engine supports these; surface them)
+- ⬜ **Job/carrier in-the-loop semantics.** The proto has `ProcessJob`/
+  `CarrierAction` + report RPCs, but the exact contract is unspecified: who acks
+  the host's S16F5/S3Fxx, whether the tool *gates* a job start or only observes,
+  and timing vs. T3. **Design this before implementing the daemon for process tools.**
+- ⬜ Trace data collection (engine: `TraceStore`, S2F23/S6F1).
+- ⬜ Limits monitoring (engine: `LimitMonitorStore`, S2F45).
+- ⬜ Substrate/E90 + module/E157 tracking (engine: `SubstrateStore`, `ModuleStore`).
+- ⬜ Terminal services / operator messages (engine: S10F1–F6) — host↔tool HMI text.
+- ⬜ Spool depth + force-flush API (engine: `SpoolStore`).
+- ⬜ `Describe` RPC: enumerate configured variables/events/alarms/commands at
+  runtime (diagnostics & tooling).
+
+### Layer 2 — Production hardening
+- ⬜ **gRPC auth / exposure.** No auth today. Bind to a Unix domain socket or
+  localhost-only, or add credentials. Never expose the API on the equipment LAN
+  unauthenticated.
+- ⬜ **`Subscribe` reconnect/replay semantics.** Define what happens to host
+  requests (commands, jobs) if the tool client disconnects and reconnects: are
+  they buffered/replayed, or dropped? Required for a 24/7 tool. (Correctness gap.)
+- ⬜ Supervised deployment (systemd unit / container), auto-restart; rely on the
+  existing spool persistence so queued host events survive a daemon restart.
+- ⬜ Expose the existing Prometheus metrics + structured logs from the daemon.
+- ⬜ Decide multi-host (HSMS-GS) story — engine supports it; v1 assumes one
+  equipment/session. Probably fine; document the assumption.
+
+### Layer 3 — Actual fab acceptance (the hard gate)
+- ⚠️ **Standards correctness is unverified.** The SECS/GEM behaviour in this repo
+  was substantially reconstructed without access to the SEMI standard texts.
+  Interop tests (secsgem-py, secs4java8, Wireshark) mitigate but do not prove
+  conformance. Subtle wire/state-machine deviations could fail a real host. This
+  is the #1 fab-readiness risk and it is *verification*, not features.
+- ⬜ Pass a specific fab's **MES qualification suite** against their real host
+  (see `docs/MES_INTEROP.md` for the punch-list). Fab acceptance is empirical
+  and per-fab.
+- ⬜ Produce the GEM **compliance statement** (S1F19/F20) + written GEM manual
+  matching the tool's actual data dictionary.
+- ⬜ Finish the **SECS-I serial driver** (FSM done; asio `serial_port` adapter
+  missing) — only if a target tool uses RS-232 rather than HSMS/TCP.
+- ⬜ Per-tool `equipment.yaml` authored to match the tool's real SVIDs/CEIDs/
+  ECIDs/alarms/recipes and the fab's spec (vendor work; the config validator helps).
+
+## Sequencing recommendation
+
+Layer 0 in order (runtime → deps → daemon → client), then Layer 1's job/carrier
+semantics, then Layer 2 hardening. Layer 3 runs in parallel and is gated by
+access to real standards and a real host — treat it as the thing that decides
+whether any of this is truly fab-ready.