alt_core_api: Introduce a IDL/code-generation for compatible API headers

[soburi]

Summary

This adds a protoc plugin that reads Arduino API definitions expressed
as protobuf services and generates C++ interface headers from them.
Protobuf is used here primarily as an IDL/DSL: the first-class source of
truth is the .proto definition, while the current generated target is
a minimal C++ compatibility header.

Motivation

The goal is not to dead-copy the existing Arduino API implementation.
Instead, this establishes an alternative API definition layer that can
describe Arduino-compatible interfaces in a structured form and generate
the required C++ surface from that definition.

Although this PR currently focuses only on generating replacement/alternative
C++ headers, the same IDL model can later be used as a base for additional
generated artifacts, including RPC stubs or adapters for other protocols.

What This Adds

• A protoc-gen-arduinoif plugin for generating C++ interface headers.
• Protobuf custom options for C++ naming, return types, argument types,
  visibility, includes, and service inheritance.
• IDL support for Arduino-style inheritance such as
  Print -> Stream -> HardwareSerial.
• Generated C++ interfaces using virtual inheritance where needed.
• A compact generation pipeline focused on the current PoC target:
  header generation only.

Design Notes

• Protobuf services represent Arduino API classes/interfaces.
• RPC methods represent callable API methods.
• Request message fields represent C++ method parameters.
• Method options map protobuf method names to Arduino-compatible C++ names,
  including overloads.
• The protobuf definitions remain useful beyond C++ header generation because
  they preserve API semantics in an inspectable IDL form.

Current Scope

This PR intentionally keeps the implementation small.
This is just only able to build hello_arduino example at this time.
It does not introduce runtime RPC transport, client/server stubs,
or full Arduino API coverage yet.
The immediate purpose is to prove that Arduino-compatible interface headers
can be generated from the IDL cleanly.

Validation

• Generated headers for the current Arduino API subset.
• Verified Print, Stream, and HardwareSerial interface generation.
• Confirmed duplicate C++ declarations are detected during generation.

[Copilot]

Pull request overview

This PR introduces an alternative Arduino Core API definition layer for Zephyr using protobuf as an IDL, adds a protoc plugin to generate C++ interface headers from .proto services, and wires it into the build (alongside a small Rust staticlib + C++ glue for a few core functions).

Changes:

• Add protoc-gen-arduinoif (Python) + .proto options and IDL sources, generating *_interface.hpp and *_types.h headers at build time.
• Add alt_core_api build integration (CMake/Kconfig) and a small no_std Rust static library with C++ wrappers.
• Adjust existing core build files/docs to point at the new IDL/codegen flow and API surface.

Reviewed changes

Copilot reviewed 32 out of 36 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
documentation/idl_codegen.md	Documents the IDL/codegen pipeline and mapping rules.
cores/arduino/zephyrPrint.h	Removes old Zephyr Print inline header (superseded by alt_core_api Print).
cores/arduino/zephyrCommon.cpp	Minor type-cast fix around min() usage.
cores/arduino/CMakeLists.txt	Removes Rust-impl-specific include/source handling (moved to alt_core_api).
alt_core_api/tools/protoc_gen_arduinoif/templates/ifc_header.hpp.j2	Jinja template for generated C++ interface headers.
alt_core_api/tools/protoc_gen_arduinoif/service_renderer.py	Renders ServiceModel into generated files via Jinja.
alt_core_api/tools/protoc_gen_arduinoif/service_model.py	Builds template-ready service/interface models from descriptors.
alt_core_api/tools/protoc_gen_arduinoif/request_context.py	Indexes messages/services for a CodeGeneratorRequest.
alt_core_api/tools/protoc_gen_arduinoif/method_spec.py	Derives C++ method signatures from RPC/input/output descriptors.
alt_core_api/tools/protoc_gen_arduinoif/enum_renderer.py	Emits C-compatible enum-only headers for shared proto files.
alt_core_api/tools/protoc_gen_arduinoif/core.py	Plugin entry logic: selects files, renders enums/services, returns response.
alt_core_api/tools/protoc_gen_arduinoif/common.py	Shared helpers + dynamic loading of generated arduino_opts_pb2.py.
alt_core_api/tools/protoc-gen-arduinoif	Protoc plugin executable wrapper.
alt_core_api/rust/src/lib.rs	no_std Rust crate root + panic handler.
alt_core_api/rust/src/common.rs	Rust implementations for a few Arduino-like core helpers (map/makeWord).
alt_core_api/rust/Cargo.toml	Rust crate metadata for building a staticlib.
alt_core_api/idl/proto/print.proto	IDL for Print interface (methods/options).
alt_core_api/idl/proto/stream.proto	IDL for Stream interface with inheritance from Print.
alt_core_api/idl/proto/hardware_serial.proto	IDL for HardwareSerial interface + related enums.
alt_core_api/idl/proto/common.proto	Shared enums intended to generate common_types.h.
alt_core_api/idl/proto/arduino_opts.proto	Custom protobuf options used by the generator.
alt_core_api/idl/proto/google/protobuf/wrappers.proto	Vendored well-known type used by the IDL (wrappers).
alt_core_api/idl/proto/google/protobuf/empty.proto	Vendored well-known type used by the IDL (Empty).
alt_core_api/idl/CMakeLists.txt	CMake pipeline to generate pb2 options + generated interface/type headers.
alt_core_api/api/apiPrint.cpp	Keeps Zephyr print helpers; removes default Print::write(buffer,size) body.
alt_core_api/api/apiCommon.cpp	C++ wrappers calling Rust extern "C" helpers.
alt_core_api/api/Print.h	New Print API surface based on generated PrintInterface.
alt_core_api/api/Stream.h	New Stream API surface based on generated StreamInterface.
alt_core_api/api/HardwareSerial.h	New HardwareSerial API surface based on generated interface header.
alt_core_api/api/Common.h	Stub compatibility header.
alt_core_api/api/ArduinoAPI.h	Minimal Arduino API compatibility header (types/min/setup/loop).
alt_core_api/api/CMakeLists.txt	Adds alt_core_api C++ sources to the build.
alt_core_api/CMakeLists.txt	Builds Rust staticlib, runs IDL generation, and adds alt_core_api subdirs.
README.md	Links the new IDL/codegen documentation.
Kconfig	Selects NANOPB when Rust implementation is enabled.
CMakeLists.txt	Switches Rust-impl branch to include/build alt_core_api.

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[Copilot]

Pull request overview

This PR introduces an IDL-driven (protobuf) definition of an Arduino-compatible API surface and a protoc plugin (protoc-gen-arduinoif) that generates minimal C++ interface headers from .proto service definitions, integrating the generation step into the Zephyr/CMake build for alt_core_api.

Changes:

• Added a Python-based protoc plugin and templates to render C++ pure-virtual interface headers (plus enum-only C headers) from protobuf IDL.
• Added Arduino API IDL .proto files (+ custom options) and CMake glue to generate headers into the build tree and add them to include paths.
• Added an alt_core_api compatibility layer (C++ headers + small API shims + Rust staticlib build) and wired it into the build when CONFIG_USE_ARDUINO_API_RUST_IMPLEMENTATION is enabled.

Reviewed changes

Copilot reviewed 32 out of 37 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
documentation/idl_codegen.md	New documentation describing the IDL/codegen flow and validation rules.
cores/arduino/zephyrPrint.h	Removes old Zephyr-specific Print inline helpers header.
cores/arduino/zephyrCommon.cpp	Minor formatting/type-cast adjustment for tone() counter computation.
cores/arduino/CMakeLists.txt	Removes Rust-implementation-specific include/source conditional blocks.
alt_core_api/tools/protoc_gen_arduinoif/templates/ifc_header.hpp.j2	Jinja2 template for generated C++ interface headers.
alt_core_api/tools/protoc_gen_arduinoif/service_renderer.py	Jinja2-based renderer for service/interface headers.
alt_core_api/tools/protoc_gen_arduinoif/service_model.py	Builds a template-ready model from service descriptors/options (incl. inheritance).
alt_core_api/tools/protoc_gen_arduinoif/request_context.py	Builds request-wide indexes for messages/services and caches inheritance lineage.
alt_core_api/tools/protoc_gen_arduinoif/method_spec.py	Converts RPC descriptors into C++ method declarations (types/names/visibility).
alt_core_api/tools/protoc_gen_arduinoif/enum_renderer.py	Renders enum-only proto files into C-compatible headers.
alt_core_api/tools/protoc_gen_arduinoif/core.py	Plugin entry logic: reads CodeGeneratorRequest, emits generated files.
alt_core_api/tools/protoc_gen_arduinoif/common.py	Shared helpers (naming, uniq) + dynamic load of arduino_opts_pb2.py via env var.
alt_core_api/tools/protoc-gen-arduinoif	Executable plugin wrapper that sets sys.path and dispatches to core.main().
alt_core_api/rust/src/lib.rs	no_std Rust staticlib crate root + panic handler.
alt_core_api/rust/src/common.rs	Rust implementations exported for C/C++ linkage (map_i32, makeWord_*).
alt_core_api/rust/Cargo.toml	Rust crate metadata for producing a staticlib.
alt_core_api/idl/proto/stream.proto	IDL for Stream service (inherits Print) + LookaheadMode enum.
alt_core_api/idl/proto/print.proto	IDL for Print service and request messages for write overloads.
alt_core_api/idl/proto/hardware_serial.proto	IDL for HardwareSerial service (inherits Stream) + serial config enums.
alt_core_api/idl/proto/google/protobuf/wrappers.proto	Vendored well-known-type proto used for scalar return wrappers.
alt_core_api/idl/proto/google/protobuf/empty.proto	Vendored google.protobuf.Empty proto used for void/no-arg mapping.
alt_core_api/idl/proto/common.proto	Shared enum-only IDL intended to generate *_types.h compatibility header.
alt_core_api/idl/proto/arduino_opts.proto	Custom protobuf options/extensions for C++ name/type/visibility/inheritance/includes.
alt_core_api/idl/CMakeLists.txt	CMake pipeline: generate arduino_opts_pb2.py, run plugin, add include dirs/targets.
alt_core_api/api/apiPrint.cpp	Removes Print::write(buffer,size) body (now provided inline in new header).
alt_core_api/api/apiCommon.cpp	Adds C++ shims calling Rust exports for map() and makeWord().
alt_core_api/api/Stream.h	Adds Stream compatibility header inheriting from generated StreamInterface.
alt_core_api/api/Print.h	Adds Print compatibility header inheriting from generated PrintInterface + inline helpers.
alt_core_api/api/HardwareSerial.h	Adds HardwareSerial compatibility header inheriting generated HardwareSerialInterface.
alt_core_api/api/Common.h	Adds a stub Common.h for compatibility.
alt_core_api/api/CMakeLists.txt	Adds apiCommon.cpp and apiPrint.cpp to the build.
alt_core_api/api/ArduinoAPI.h	Adds minimal Arduino core type/function declarations (e.g., byte, pin_size_t, min).
alt_core_api/CMakeLists.txt	Adds Rust staticlib build + links it; adds idl/ and api/ subdirs and dependencies.
README.md	Adds a link to the new IDL/codegen documentation.
Kconfig	Ensures NANOPB is selected when enabling the Rust implementation path.
CMakeLists.txt	Switches the Rust-implementation build path to include alt_core_api instead of the blobbed API.
.gitignore	Updates ignored Rust lockfile path to alt_core_api/rust/Cargo.lock.

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[Copilot]

Pull request overview

This PR introduces an IDL-driven code generation pipeline (protoc-gen-arduinoif) for producing Arduino-compatible C++ interface headers from .proto service definitions, and wires it into the Zephyr build as an alternative “core API” implementation path.

Changes:

• Added a Python protoc plugin + templates to generate C++ interface headers (and enum-only type headers) from Arduino API .proto IDL.
• Added initial Arduino IDL protos (Print, Stream, HardwareSerial, plus shared enums/options) and CMake integration to generate headers during builds.
• Added an alt_core_api implementation path (C++ headers + some Rust-backed C ABI helpers) and hooked it up behind CONFIG_USE_ARDUINO_API_RUST_IMPLEMENTATION.

Reviewed changes

Copilot reviewed 32 out of 37 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
documentation/idl_codegen.md	Documents the new Arduino IDL/codegen flow and build integration.
cores/arduino/zephyrPrint.h	Removes the previous Zephyr Print inline helper header.
cores/arduino/zephyrCommon.cpp	Formatting / type adjustment for min() usage in tone().
cores/arduino/CMakeLists.txt	Removes rust-specific include/source tweaks in this directory.
alt_core_api/tools/protoc_gen_arduinoif/templates/ifc_header.hpp.j2	Jinja template for generated C++ interface headers.
alt_core_api/tools/protoc_gen_arduinoif/service_renderer.py	Renders ServiceModel via Jinja templates.
alt_core_api/tools/protoc_gen_arduinoif/service_model.py	Builds template-ready service models incl. inheritance/includes.
alt_core_api/tools/protoc_gen_arduinoif/request_context.py	Builds request-wide indices for messages/services/lineage cache.
alt_core_api/tools/protoc_gen_arduinoif/method_spec.py	Maps RPCs and message fields into C++ method signatures.
alt_core_api/tools/protoc_gen_arduinoif/enum_renderer.py	Emits enum-only C headers for shared proto files.
alt_core_api/tools/protoc_gen_arduinoif/core.py	Plugin entry logic: parse request and emit generated files.
alt_core_api/tools/protoc_gen_arduinoif/common.py	Shared helpers + dynamic loading of arduino_opts_pb2.
alt_core_api/tools/protoc-gen-arduinoif	protoc plugin entrypoint script.
alt_core_api/rust/src/lib.rs	no_std Rust library scaffolding + panic handler.
alt_core_api/rust/src/common.rs	Exports C ABI helpers (e.g., map_i32, makeWord_*).
alt_core_api/rust/Cargo.toml	Rust staticlib crate definition for alt_core_api.
alt_core_api/idl/proto/stream.proto	IDL proto for Stream and its methods + inheritance from Print.
alt_core_api/idl/proto/print.proto	IDL proto for Print incl. overload mapping to write.
alt_core_api/idl/proto/hardware_serial.proto	IDL proto for HardwareSerial + enums/config and inheritance from Stream.
alt_core_api/idl/proto/google/protobuf/wrappers.proto	Vendored wrappers proto used by the IDL.
alt_core_api/idl/proto/google/protobuf/empty.proto	Vendored Empty proto used by the IDL.
alt_core_api/idl/proto/common.proto	Shared enum-only proto intended to generate *_types.h.
alt_core_api/idl/proto/arduino_opts.proto	Custom options for C++ names/types/includes/inheritance/visibility.
alt_core_api/idl/CMakeLists.txt	CMake: generate arduino_opts_pb2.py + run plugin to produce headers.
alt_core_api/api/apiPrint.cpp	Removes Print::write(buffer,size) impl (moved inline to header).
alt_core_api/api/apiCommon.cpp	New C++ wrappers that call into Rust-exported C functions.
alt_core_api/api/Stream.h	C++ API header bridging Stream to generated StreamInterface.
alt_core_api/api/Print.h	C++ API header bridging Print to generated PrintInterface.
alt_core_api/api/HardwareSerial.h	C++ API header bridging HardwareSerial to generated interface + enums.
alt_core_api/api/Common.h	Stub compatibility header.
alt_core_api/api/CMakeLists.txt	Adds apiCommon.cpp and apiPrint.cpp to the build.
alt_core_api/api/ArduinoAPI.h	Arduino API surface/types for the alt_core_api path.
alt_core_api/CMakeLists.txt	Builds Rust staticlib, adds IDL + API subdirs, wires dependencies.
README.md	Adds link to the new IDL/codegen documentation.
Kconfig	Ensures NANOPB is selected when using the Rust-based implementation.
CMakeLists.txt	Switches Rust implementation path to build alt_core_api instead of inlined Rust build logic.
.gitignore	Updates ignored Cargo.lock location to alt_core_api/rust/Cargo.lock.

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[Copilot]

Pull request overview

This PR introduces an Arduino API IDL layer (protobuf-based) and a protoc plugin to generate Arduino-compatible C++ interface headers, then wires that generated surface into an alternative alt_core_api build path (including a small Rust staticlib).

Changes:

• Added protoc-gen-arduinoif (Python) plus templates/models to generate C++ pure-virtual interface headers from .proto services and enums.
• Added initial Arduino IDL .proto definitions (e.g., Print, Stream, HardwareSerial, and shared enums) and CMake integration to run the generator during builds.
• Added alt_core_api compatibility headers/impls and a Rust staticlib, and switched the “Rust implementation” build path to build alt_core_api.

Reviewed changes

Copilot reviewed 31 out of 36 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
documentation/idl_codegen.md	Documents the IDL/codegen design, mapping rules, and build integration.
cores/arduino/zephyrPrint.h	Removes the old Zephyr-specific Print inline header implementation.
cores/arduino/zephyrCommon.cpp	Adjusts min() call to avoid mixed-type template deduction issues.
cores/arduino/CMakeLists.txt	Removes Rust-mode conditional sources/include ordering logic.
alt_core_api/tools/protoc_gen_arduinoif/templates/ifc_header.hpp.j2	Jinja2 template for generated C++ interface headers (methods, enums, inheritance).
alt_core_api/tools/protoc_gen_arduinoif/service_renderer.py	Renders ServiceModel using the interface-header template.
alt_core_api/tools/protoc_gen_arduinoif/service_model.py	Builds template-ready service/interface models incl. inheritance and includes.
alt_core_api/tools/protoc_gen_arduinoif/request_context.py	Builds per-request indexes for messages/services used by the generator.
alt_core_api/tools/protoc_gen_arduinoif/method_spec.py	Converts RPC methods + options into C++ method declarations/keys.
alt_core_api/tools/protoc_gen_arduinoif/enum_renderer.py	Generates _types.h headers for enum-only proto files.
alt_core_api/tools/protoc_gen_arduinoif/core.py	protoc plugin core: parses request and emits generated files.
alt_core_api/tools/protoc_gen_arduinoif/common.py	Shared helpers (naming, uniq) and dynamic loading of opts pb2 module.
alt_core_api/tools/protoc-gen-arduinoif	Plugin entrypoint script invoked by protoc.
alt_core_api/rust/src/lib.rs	no_std Rust library scaffold and panic handler for the staticlib.
alt_core_api/rust/src/common.rs	Rust exports for core Arduino-like helpers (map, makeWord).
alt_core_api/rust/Cargo.toml	Rust crate configuration (staticlib).
alt_core_api/idl/proto/stream.proto	IDL for Stream service and LookaheadMode enum.
alt_core_api/idl/proto/print.proto	IDL for Print service + write/flush/availableForWrite mapping.
alt_core_api/idl/proto/hardware_serial.proto	IDL for HardwareSerial service plus serial-related enums.
alt_core_api/idl/proto/google/protobuf/wrappers.proto	Vendored protobuf wrappers used as IDL return message types.
alt_core_api/idl/proto/google/protobuf/empty.proto	Vendored protobuf Empty message for void/no-args.
alt_core_api/idl/proto/common.proto	Shared Arduino enums emitted as *_types.h.
alt_core_api/idl/proto/arduino_opts.proto	Custom protobuf options for C++ codegen behavior.
alt_core_api/idl/CMakeLists.txt	Adds nanopb + codegen pipeline to generate interface headers during build.
alt_core_api/api/apiPrint.cpp	Keeps Zephyr print helpers; removes out-of-line default Print::write(buffer,size).
alt_core_api/api/apiCommon.cpp	Adds C++ wrappers calling into Rust exports for common Arduino helpers.
alt_core_api/api/Stream.h	Defines arduino::Stream in terms of generated StreamInterface.
alt_core_api/api/Print.h	Defines arduino::Print in terms of generated PrintInterface + inline helpers.
alt_core_api/api/HardwareSerial.h	Defines arduino::HardwareSerial in terms of generated interface + config enum.
alt_core_api/api/Common.h	Adds a compatibility stub header.
alt_core_api/api/CMakeLists.txt	Builds the alt_core_api C++ API sources.
alt_core_api/api/ArduinoAPI.h	Minimal Arduino API base types/utilities for the alt API path.
alt_core_api/CMakeLists.txt	Builds the Rust staticlib and adds idl/ + api/ subdirectories.
README.md	Links new IDL codegen documentation.
CMakeLists.txt	Switches the Rust-implementation path to include/build alt_core_api.
.gitignore	Updates ignored Cargo.lock path to alt_core_api/rust/Cargo.lock.

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[Copilot]

Pull request overview

This PR introduces an Arduino API IDL layer (protobuf-based) plus a protoc plugin that generates Arduino-compatible C++ interface headers, and wires that into the Zephyr build via the new alt_core_api module (including an initial Rust staticlib).

Changes:

• Add protoc-gen-arduinoif (Python) and protobuf option schema to generate C++ interface headers from .proto services.
• Add initial Arduino IDL .proto sources (Print/Stream/HardwareSerial + shared enums) and CMake integration to generate headers during builds.
• Add alt_core_api compatibility headers and a Rust static library build/link step, updating top-level build selection and docs.

Reviewed changes

Copilot reviewed 31 out of 36 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
documentation/idl_codegen.md	Documents the IDL/codegen pipeline and how to invoke it.
cores/arduino/zephyrPrint.h	Removes the old Zephyr Print inline header.
cores/arduino/zephyrCommon.cpp	Adjusts min() call typing/formatting for tone counter computation.
cores/arduino/CMakeLists.txt	Removes Rust-implementation conditional include/source wiring from core.
alt_core_api/tools/protoc_gen_arduinoif/templates/ifc_header.hpp.j2	Jinja template for generated C++ interface headers.
alt_core_api/tools/protoc_gen_arduinoif/service_renderer.py	Renders ServiceModel into generated interface header files.
alt_core_api/tools/protoc_gen_arduinoif/service_model.py	Builds the template-ready model (includes, inheritance, methods, enums).
alt_core_api/tools/protoc_gen_arduinoif/request_context.py	Indexes messages/services across the CodeGeneratorRequest.
alt_core_api/tools/protoc_gen_arduinoif/method_spec.py	Converts RPC + request/response messages into C++ method signatures.
alt_core_api/tools/protoc_gen_arduinoif/enum_renderer.py	Emits C-compatible headers for enum-only proto files.
alt_core_api/tools/protoc_gen_arduinoif/core.py	Main protoc plugin implementation and error handling.
alt_core_api/tools/protoc_gen_arduinoif/common.py	Shared helpers + dynamic loading of arduino_opts_pb2.py.
alt_core_api/tools/protoc-gen-arduinoif	Plugin entrypoint script used by protoc.
alt_core_api/rust/src/lib.rs	Defines the no_std Rust crate entry and panic handler.
alt_core_api/rust/src/common.rs	Implements C ABI helpers in Rust (e.g., map_i32, makeWord_*).
alt_core_api/rust/Cargo.toml	Rust crate definition for building a staticlib.
alt_core_api/idl/proto/stream.proto	Defines Stream service and LookaheadMode enum in IDL.
alt_core_api/idl/proto/print.proto	Defines Print service and write/flush APIs in IDL.
alt_core_api/idl/proto/hardware_serial.proto	Defines HardwareSerial service and serial config enums in IDL.
alt_core_api/idl/proto/google/protobuf/wrappers.proto	Vendors protobuf wrappers proto for local IDL compilation.
alt_core_api/idl/proto/google/protobuf/empty.proto	Vendors protobuf Empty proto for local IDL compilation.
alt_core_api/idl/proto/common.proto	Shared Arduino enums intended for _types.h generation.
alt_core_api/idl/proto/arduino_opts.proto	Declares custom protobuf options for C++ generation control.
alt_core_api/idl/CMakeLists.txt	Adds nanopb integration + custom commands/targets to run codegen.
alt_core_api/api/apiPrint.cpp	Keeps Zephyr Print helpers; removes moved default Print::write impl.
alt_core_api/api/apiCommon.cpp	Adds C++ wrappers calling into Rust ABI implementations.
alt_core_api/api/Stream.h	Adds Stream compatibility type inheriting generated interface.
alt_core_api/api/Print.h	Adds Print compatibility type inheriting generated interface + helpers.
alt_core_api/api/HardwareSerial.h	Adds HardwareSerial compatibility type inheriting generated interface.
alt_core_api/api/Common.h	Adds a stub Common header for compatibility.
alt_core_api/api/CMakeLists.txt	Adds alt_core_api C++ sources to the build.
alt_core_api/api/ArduinoAPI.h	Adds the minimal Arduino API surface/types used by cores.
alt_core_api/CMakeLists.txt	Adds Rust build/link + hooks in IDL and API subdirectories.
README.md	Links to the new IDL/codegen documentation.
CMakeLists.txt	Switches Rust-implementation branch to include/build alt_core_api.
.gitignore	Updates ignored Cargo.lock location for the new Rust crate path.

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[Copilot]

Pull request overview

This PR introduces a protobuf-based IDL for Arduino-compatible APIs and a protoc plugin (protoc-gen-arduinoif) that generates minimal C++ interface headers from .proto service definitions, integrating this into the Zephyr/CMake build and wiring an alternative alt_core_api implementation path (including a Rust staticlib).

Changes:

• Added a Python protoc plugin + templates to render C++ interface headers (and enum-only C type headers) from .proto services/enums.
• Added initial Arduino IDL .proto definitions (Print, Stream, HardwareSerial, shared common enums) and CMake integration to generate headers during the build.
• Added alt_core_api headers/sources (and Rust staticlib build) to provide an alternative Arduino API surface when CONFIG_USE_ARDUINO_API_RUST_IMPLEMENTATION is enabled.

Reviewed changes

Copilot reviewed 32 out of 37 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
documentation/idl_codegen.md	Documents the IDL/codegen flow, mappings, and build integration.
cores/arduino/zephyrPrint.h	Removes the previous Zephyr-specific Print inline header implementation.
cores/arduino/zephyrCommon.cpp	Minor update to tone() count computation formatting/casting.
cores/arduino/CMakeLists.txt	Removes conditional rust-impl include/source wiring (moved to alt_core_api).
alt_core_api/tools/protoc_gen_arduinoif/templates/ifc_header.hpp.j2	Jinja template for generated C++ interface headers.
alt_core_api/tools/protoc_gen_arduinoif/service_renderer.py	Renders ServiceModel into generated files via Jinja.
alt_core_api/tools/protoc_gen_arduinoif/service_model.py	Builds template-ready service models (includes inheritance/includes/overload checks).
alt_core_api/tools/protoc_gen_arduinoif/request_context.py	Indexes request descriptors (messages/services) for generation.
alt_core_api/tools/protoc_gen_arduinoif/method_spec.py	Maps RPCs + message fields/options into C++ method signatures.
alt_core_api/tools/protoc_gen_arduinoif/enum_renderer.py	Emits C-compatible headers for enum-only proto files.
alt_core_api/tools/protoc_gen_arduinoif/core.py	Plugin entry logic: parse request and emit generated files or errors.
alt_core_api/tools/protoc_gen_arduinoif/common.py	Shared helpers + dynamic loading of arduino_opts_pb2.py via env var.
alt_core_api/tools/protoc-gen-arduinoif	Executable plugin entrypoint script for protoc.
alt_core_api/rust/src/lib.rs	no_std Rust crate entry with panic handler for staticlib.
alt_core_api/rust/src/common.rs	Rust FFI functions intended to back Arduino API helpers (map, makeWord).
alt_core_api/rust/Cargo.toml	Declares Rust staticlib crate configuration.
alt_core_api/idl/proto/stream.proto	Defines Stream service + enums and inheritance from Print.
alt_core_api/idl/proto/print.proto	Defines Print service and method mapping options (overloads via cpp_name).
alt_core_api/idl/proto/hardware_serial.proto	Defines HardwareSerial service + enums and inheritance from Stream.
alt_core_api/idl/proto/google/protobuf/wrappers.proto	Vendored well-known type definitions used by the IDL.
alt_core_api/idl/proto/google/protobuf/empty.proto	Vendored google.protobuf.Empty definition used by the IDL.
alt_core_api/idl/proto/common.proto	Shared Arduino-ish enum definitions for type header generation.
alt_core_api/idl/proto/arduino_opts.proto	Protobuf custom options used to control C++ generation.
alt_core_api/idl/CMakeLists.txt	CMake pipeline for generating pb2 options + generated interface/type headers.
alt_core_api/api/apiPrint.cpp	Keeps Zephyr printing helpers; removes the Print::write(buffer,size) impl here.
alt_core_api/api/apiCommon.cpp	Adds C++ wrappers calling into Rust FFI (map_i32, makeWord_*).
alt_core_api/api/Stream.h	Defines Stream C++ type inheriting generated StreamInterface.
alt_core_api/api/Print.h	Defines Print type inheriting generated PrintInterface + inline helpers/defaults.
alt_core_api/api/HardwareSerial.h	Defines HardwareSerial type inheriting generated HardwareSerialInterface.
alt_core_api/api/Common.h	Adds stub compatibility header.
alt_core_api/api/CMakeLists.txt	Adds alt_core_api/api sources to the build.
alt_core_api/api/ArduinoAPI.h	Defines core Arduino API types/helpers for the alt_core_api path.
alt_core_api/CMakeLists.txt	Adds Rust build + links staticlib; adds idl and api subdirectories.
README.md	Adds link to the new IDL codegen documentation.
CMakeLists.txt	Switches rust-implementation branch to build alt_core_api instead of blob sources.
.gitignore	Updates ignored Cargo.lock path to the new rust crate location.

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[Copilot]

Pull request overview

Introduces a protobuf-based IDL layer and a protoc plugin (protoc-gen-arduinoif) to generate Arduino-compatible C++ interface headers, and wires this into the Zephyr/CMake build when using the alternative (Rust-backed) API implementation.

Changes:

• Added a Python protoc plugin + Jinja2 templates to generate *_interface.hpp and *_types.h headers from .proto service/enum definitions.
• Added Arduino IDL .proto sources (including custom options) and CMake build steps to generate headers during builds.
• Added an alternative API surface (alt_core_api/api) plus Rust staticlib build integration, and updated top-level build wiring/docs accordingly.

Reviewed changes

Copilot reviewed 31 out of 36 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
documentation/idl_codegen.md	Documents the IDL/codegen flow, build integration, and validation rules.
cores/arduino/zephyrPrint.h	Removes legacy inline Print helpers previously located under cores/arduino.
cores/arduino/CMakeLists.txt	Removes Rust-implementation-specific include/source wiring from the core build.
alt_core_api/tools/protoc_gen_arduinoif/templates/ifc_header.hpp.j2	Adds the Jinja template for generated C++ interface headers.
alt_core_api/tools/protoc_gen_arduinoif/service_renderer.py	Adds renderer that produces interface headers from the service model.
alt_core_api/tools/protoc_gen_arduinoif/service_model.py	Adds service-to-model builder including inheritance/include handling.
alt_core_api/tools/protoc_gen_arduinoif/request_context.py	Adds request indexing for messages/services and lineage cache.
alt_core_api/tools/protoc_gen_arduinoif/method_spec.py	Adds RPC-to-C++ method signature inference and option handling.
alt_core_api/tools/protoc_gen_arduinoif/enum_renderer.py	Adds generation of enum-only *_types.h headers.
alt_core_api/tools/protoc_gen_arduinoif/core.py	Adds plugin entry logic for iterating generated outputs.
alt_core_api/tools/protoc_gen_arduinoif/common.py	Adds shared helpers and dynamic loading of arduino_opts_pb2.py.
alt_core_api/tools/protoc-gen-arduinoif	Adds the protoc plugin entrypoint script.
alt_core_api/rust/src/lib.rs	Adds no_std Rust crate root and panic handler.
alt_core_api/rust/src/common.rs	Adds Rust-backed implementations intended to be called from C/C++.
alt_core_api/rust/Cargo.toml	Adds Rust crate metadata for building a static library.
alt_core_api/idl/proto/print.proto	Defines Print service/methods in the IDL.
alt_core_api/idl/proto/stream.proto	Defines Stream service and inheritance from Print in the IDL.
alt_core_api/idl/proto/hardware_serial.proto	Defines HardwareSerial service, enums, and inheritance from Stream.
alt_core_api/idl/proto/common.proto	Defines shared enums to be emitted as *_types.h.
alt_core_api/idl/proto/arduino_opts.proto	Defines custom protobuf options driving C++ codegen behavior.
alt_core_api/idl/proto/google/protobuf/wrappers.proto	Vendors well-known wrappers needed by the IDL.
alt_core_api/idl/proto/google/protobuf/empty.proto	Vendors google.protobuf.Empty needed by the IDL.
alt_core_api/idl/proto/google/protobuf/descriptor.proto	Vendors descriptor proto to support custom options.
alt_core_api/idl/CMakeLists.txt	Adds CMake pipeline to generate headers via the plugin and include them in builds.
alt_core_api/api/apiPrint.cpp	Keeps Zephyr Print formatting helpers; removes duplicated default write() impl.
alt_core_api/api/apiCommon.cpp	Adds C/C++ shims that call into the Rust staticlib.
alt_core_api/api/Print.h	Adds Print class wired to generated PrintInterface plus inline helpers/defaults.
alt_core_api/api/Stream.h	Adds Stream class wired to generated StreamInterface.
alt_core_api/api/HardwareSerial.h	Adds HardwareSerial class wired to generated HardwareSerialInterface.
alt_core_api/api/Common.h	Adds a stub compatibility header.
alt_core_api/api/ArduinoAPI.h	Adds Arduino API header surface (types/funcs) for the alt core.
alt_core_api/api/CMakeLists.txt	Adds build sources for the alt API C++ layer.
alt_core_api/CMakeLists.txt	Adds Rust staticlib build/link integration + includes the IDL and API subdirs.
README.md	Links the new IDL/codegen documentation.
CMakeLists.txt	Switches Rust-implementation builds to include alt_core_api instead of the blob API.
.gitignore	Adjusts ignored Cargo.lock path to match new Rust crate location.

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[Copilot]

Pull request overview

This PR introduces an IDL/code-generation pipeline (protoc-gen-arduinoif) that treats .proto service definitions as the source-of-truth for Arduino-compatible APIs, generating C++ “interface header” surfaces and wiring that into the alt_core_api build when the Rust implementation is enabled.

Changes:

• Add a Python protoc plugin + templates to generate C++ interface headers from protobuf service descriptors (with custom options for C++ naming/types/inheritance).
• Add initial Arduino IDL protos (Print, Stream, HardwareSerial, and shared enums) and CMake integration to generate headers at build time.
• Introduce alt_core_api C++ compatibility headers and a Rust staticlib (with C++ wrappers) used when CONFIG_USE_ARDUINO_API_RUST_IMPLEMENTATION is enabled.

Reviewed changes

Copilot reviewed 33 out of 38 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
documentation/idl_codegen.md	Adds documentation for the protoc plugin flow, build integration, and IDL mapping rules.
cores/arduino/zephyrPrint.h	Removes the old Zephyr-specific Print inline implementation header.
cores/arduino/zephyrCommon.cpp	Adjusts min() usage to avoid truncation/dangling issues in tone() count calculation.
cores/arduino/CMakeLists.txt	Removes Rust-implementation-specific include/source conditionals now handled via alt_core_api.
alt_core_api/tools/protoc_gen_arduinoif/templates/ifc_header.hpp.j2	Adds Jinja template for generated C++ interface headers.
alt_core_api/tools/protoc_gen_arduinoif/service_renderer.py	Adds renderer that turns ServiceModel into generated files via Jinja.
alt_core_api/tools/protoc_gen_arduinoif/service_model.py	Adds model builder with inheritance resolution, include collection, and overload validation.
alt_core_api/tools/protoc_gen_arduinoif/request_context.py	Adds request-wide descriptor indexes for messages/services and lineage caching.
alt_core_api/tools/protoc_gen_arduinoif/method_spec.py	Adds method signature derivation from RPCs + options, with validation.
alt_core_api/tools/protoc_gen_arduinoif/enum_renderer.py	Adds enum-only proto rendering to *_types.h.
alt_core_api/tools/protoc_gen_arduinoif/core.py	Adds plugin entry logic: parse request, generate headers, report errors.
alt_core_api/tools/protoc_gen_arduinoif/common.py	Adds shared utilities and PROTOC_GEN_ARDUINOIF_PB2 loader for custom options.
alt_core_api/tools/protoc-gen-arduinoif	Adds the protoc plugin executable entrypoint script.
alt_core_api/rust/src/lib.rs	Adds no_std Rust crate entry and panic handler for staticlib use.
alt_core_api/rust/src/common.rs	Adds Rust FFI implementations for core helpers (map, makeWord).
alt_core_api/rust/Cargo.toml	Adds Rust crate metadata for building a staticlib.
alt_core_api/idl/proto/print.proto	Defines Print service and request messages, mapping to C++ write overloads and helpers.
alt_core_api/idl/proto/stream.proto	Defines Stream service inheriting from Print plus LookaheadMode enum.
alt_core_api/idl/proto/hardware_serial.proto	Defines HardwareSerial service inheriting from Stream plus serial config enums and operator bool.
alt_core_api/idl/proto/common.proto	Adds shared Arduino enums for generated common_types.h.
alt_core_api/idl/proto/arduino_opts.proto	Adds custom protobuf options used to control C++ generation.
alt_core_api/idl/proto/google/protobuf/empty.proto	Vendors protobuf well-known type for Empty.
alt_core_api/idl/proto/google/protobuf/wrappers.proto	Vendors protobuf well-known wrapper messages for scalar returns.
alt_core_api/idl/proto/google/protobuf/descriptor.proto	Vendors descriptor.proto to support custom options compilation.
alt_core_api/idl/CMakeLists.txt	Adds CMake pipeline to generate arduino_opts_pb2.py then run protoc-gen-arduinoif.
alt_core_api/api/apiPrint.cpp	Removes Print::write(const uint8_t*, size_t) implementation from .cpp (now inline in header).
alt_core_api/api/apiCommon.cpp	Adds C++ wrappers that call into Rust FFI for map()/makeWord().
alt_core_api/api/Print.h	Adds compatibility Print class bridging generated PrintInterface and Zephyr print helpers.
alt_core_api/api/Stream.h	Adds compatibility Stream class bridging generated StreamInterface.
alt_core_api/api/HardwareSerial.h	Adds compatibility HardwareSerial class bridging generated HardwareSerialInterface.
alt_core_api/api/Common.h	Adds stub Common.h for compatibility includes.
alt_core_api/api/ArduinoAPI.h	Adds minimal Arduino API surface/types and includes generated shared enum header.
alt_core_api/api/CMakeLists.txt	Adds Zephyr build sources for the compatibility API layer.
alt_core_api/CMakeLists.txt	Adds Rust build (cargo) + links staticlib and integrates IDL + API subdirs.
README.md	Links the new Arduino IDL code generation documentation.
Kconfig	Ensures NANOPB is selected when using the Rust implementation path.
CMakeLists.txt	Switches Rust-implementation build to include and build alt_core_api instead of inline Rust build logic.
.gitignore	Updates ignored Cargo.lock path to alt_core_api/rust/Cargo.lock.

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