daemon: sched/ — the concurrency governor + schedule-window evaluation (build step 4)

The scheduling brain, built against CORE's headers (vdm/engine.hpp,
vdm/segment/budget.hpp) — signatures only; the Engine bodies land in
CORE stage 8 and the Scheduler that wires governor <-> store <-> engine
<-> timer comes after that (daemon/docs/deferrals.md D4).

- sched/governor — a pure decision function. In: a snapshot of every
  task's coarse RunState and every queue's state (schedule windows
  pre-resolved). Out: {to_start, to_resume, to_pause, pause_reasons,
  priority_order}. Enforces, all in TASK units per ADR 0011 §1:
  connection.maxConcurrentDownloads; the min(that, maxActiveSegments)
  clamp (§2); Queue.maxConcurrent; the per-host task cap (§4); and a
  stopped queue / closed window runs nothing. Never touches a task
  paused for `user` or CORE's `auto` (ADR 0013 §3) — only Schedule /
  QueueStopped / AdmissionReconcile are auto-resumable. Deterministic:
  main-list before queued-in-queue, then queue order, then FIFO, then
  task_id.
- sched/schedule_window — window_open(Schedule, local tm): disabled =>
  always open; `once` => date + time match; `periodic` => weekday in
  daysOfWeek (empty = every day) + time in [start, stop); null start =>
  midnight, null stop => end of day, stop < start => overnight window.
  Pure; re-evaluated every tick, no cached instants.
- veloxd_sched static lib; veloxd links it (nothing calls it yet).

Tests (ASan+UBSan and TSan clean): veloxd.sched_window (10 window
cases incl. overnight, once, null bounds), veloxd.sched_governor
(global/clamp/per-queue/per-host caps, stop vs window pause reasons,
resume-only-governor-reasons, auth-pause untouched, admission
reconcile, determinism under shuffled input). 32 daemon/cli tests
green; full tree green.

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Upd9WhG9oppieig5nRDLig

daemon/CMakeLists.txt

@@ -44,6 +44,18 @@ target_compile_features(veloxd_store PUBLIC cxx_std_23)
 target_compile_options(veloxd_store PRIVATE -Wall -Wextra -Wpedantic -Werror)
 target_link_libraries(veloxd_store PUBLIC SQLite::SQLite3 PRIVATE OpenSSL::Crypto)
 
+# --- veloxd_sched — the concurrency governor (pure; no engine link yet, see
+#     daemon/docs/deferrals.md D4) ---------------------------------------------------
+add_library(veloxd_sched STATIC
+    src/sched/schedule_window.cpp
+    src/sched/governor.cpp
+)
+add_library(velox::daemon_sched ALIAS veloxd_sched)
+target_include_directories(veloxd_sched PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/src)
+target_compile_features(veloxd_sched PUBLIC cxx_std_23)
+target_compile_options(veloxd_sched PRIVATE -Wall -Wextra -Wpedantic -Werror)
+target_link_libraries(veloxd_sched PUBLIC velox::proto nlohmann_json::nlohmann_json)
+
 # --- veloxd_rpc — the RPC transports + dispatcher ------------------------------------
 add_library(veloxd_rpc STATIC
     src/rpc/runtime_dir.cpp
@@ -68,7 +80,7 @@ target_link_libraries(veloxd_rpc
 add_executable(veloxd src/main.cpp)
 target_compile_features(veloxd PRIVATE cxx_std_23)
 target_compile_options(veloxd PRIVATE -Wall -Wextra -Wpedantic -Werror)
-target_link_libraries(veloxd PRIVATE veloxd_rpc)
+target_link_libraries(veloxd PRIVATE veloxd_rpc veloxd_sched)
 
 if(VELOX_BUILD_TESTS AND EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/tests/CMakeLists.txt)
     add_subdirectory(tests)