feat: ADR-095/096 sparse attention — on-ESP32 temporal head + AETHER train wire (#513)

firmware/esp32-csi-node/components/ruv_temporal/.cargo/config.toml

@@ -0,0 +1,10 @@
+# Per-component cargo config so `cargo build` picks the xtensa target
+# without the caller having to remember `--target xtensa-esp32s3-none-elf`.
+# CMakeLists.txt still passes --target explicitly for clarity.
+
+[build]
+target = "xtensa-esp32s3-none-elf"
+
+# The esp toolchain ships precompiled core and alloc for
+# xtensa-esp32s3-none-elf, so build-std is unnecessary and (as of the
+# 2025-09-16 esp nightly) actively broken on portable_simd.

firmware/esp32-csi-node/components/ruv_temporal/CMakeLists.txt

@@ -0,0 +1,49 @@
+# ESP-IDF component manifest for the ruv_temporal Rust staticlib (ADR-095).
+#
+# Build flow:
+#   - When CONFIG_CSI_TEMPORAL_HEAD_ENABLED is OFF (default): register an
+#     empty stub. main/temporal_task.c compiles the no-op shim path, no
+#     cargo, no Rust toolchain dependency. Default firmware build is
+#     unaffected.
+#   - When CONFIG_CSI_TEMPORAL_HEAD_ENABLED is ON: invoke
+#     `cargo +esp build --release --target xtensa-esp32s3-none-elf`,
+#     register the resulting libruv_temporal.a, and expose include/.
+#
+# add_custom_command is intentionally placed AFTER idf_component_register
+# because ESP-IDF runs every component's CMakeLists.txt twice — once in
+# script mode for dependency discovery (where add_custom_command is
+# forbidden), and once for the actual build.
+
+if(NOT CONFIG_CSI_TEMPORAL_HEAD_ENABLED)
+    # Feature disabled — register an empty component so the directory's
+    # mere existence doesn't break the build, but do NOT invoke cargo
+    # or pull include/ onto consumers' include paths (the C ABI header
+    # would advertise capabilities we cannot honour).
+    idf_component_register()
+    return()
+endif()
+
+set(RUV_TEMPORAL_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
+set(RUV_TEMPORAL_TARGET "xtensa-esp32s3-none-elf")
+set(RUV_TEMPORAL_PROFILE "release")
+set(RUV_TEMPORAL_LIB
+    "${RUV_TEMPORAL_DIR}/target/${RUV_TEMPORAL_TARGET}/${RUV_TEMPORAL_PROFILE}/libruv_temporal.a")
+
+idf_component_register(
+    SRCS "shim.c"
+    INCLUDE_DIRS "include"
+    PRIV_REQUIRES "esp_common"
+)
+
+# Custom command + target run only at build time, not in script mode.
+add_custom_command(
+    OUTPUT "${RUV_TEMPORAL_LIB}"
+    WORKING_DIRECTORY "${RUV_TEMPORAL_DIR}"
+    COMMAND cargo +esp build --release --target ${RUV_TEMPORAL_TARGET}
+    COMMENT "Building ruv_temporal Rust staticlib for ${RUV_TEMPORAL_TARGET}"
+    VERBATIM
+)
+add_custom_target(ruv_temporal_rust_build ALL DEPENDS "${RUV_TEMPORAL_LIB}")
+
+add_dependencies(${COMPONENT_LIB} ruv_temporal_rust_build)
+target_link_libraries(${COMPONENT_LIB} INTERFACE "${RUV_TEMPORAL_LIB}")

firmware/esp32-csi-node/components/ruv_temporal/Cargo.toml

@@ -0,0 +1,35 @@
+[package]
+name = "ruv_temporal"
+version = "0.1.0"
+edition = "2021"
+license = "MIT"
+description = "ESP32-S3 on-device temporal head for WiFi-DensePose (ADR-095, #513)"
+publish = false
+
+[lib]
+crate-type = ["staticlib"]
+name = "ruv_temporal"
+
+# Don't get pulled into the v2 workspace — this crate cross-compiles to
+# xtensa-esp32s3-none-elf, the workspace targets host x86_64.
+[workspace]
+
+[dependencies]
+ruvllm_sparse_attention = { path = "../../../../vendor/ruvector/crates/ruvllm_sparse_attention", default-features = false, features = ["fp16"] }
+
+# Minimal no_std + alloc plumbing. esp-alloc supplies a GlobalAlloc that
+# punches through to ESP-IDF's heap_caps_malloc; critical-section provides
+# the lock primitive linked_list_allocator wants on no_std targets.
+esp-alloc = "0.8"
+critical-section = "1"
+
+[profile.release]
+opt-level = "s"
+lto = true
+codegen-units = 1
+panic = "abort"
+strip = true
+
+[profile.dev]
+opt-level = 1
+panic = "abort"