Create Code Generation Plugin System

[Kinflou]

Create Code Generation Plugin System

Updated 2026-08-30 for accuracy. core now has a minimal built-in
generator, not a todo!() stub: core/src/codelib_gen/{mod.rs,rust.rs} —
find_generator("rust", _) returns a synchronous fn(&Vec<FrozenUnit>) -> String that emits structs / enums / traits. There is still no dynamic
loading, ABI, plugin discovery or version negotiation — that substance is what
remains here.

The earlier, more complete design lives in ComlineProject/generation
(code_gen = source-text emission; lib_gen = a buildable crate skeleton;
rust_c_ffi + rust_abi_stable flavors). It is unmigrated — it imports the
removed comline_core::…::basic_storage. Reviving it is part of this issue.

Consumer-facing hook: the code-generation output-config doc specs a
comline.toml [generate] mode = "code" | "lib" | "dylib" that sits on top
of this issue — code = the built-in generator, lib / dylib = lib_gen.

Priority

P1 (High) - Enables language-specific code generation

Labels

• core
• codegen
• plugins
• P1

Description

Build the plugin architecture for code generators. This allows language-specific generators to be developed as separate libraries and loaded dynamically.

Requirements:

• Stable Rust ABI interface (challenging!)
• Dynamic library loading
• Plugin discovery
• Version compatibility checking

Current State

• core/src/codelib_gen/mod.rs — find_generator(name, version), hardcoded
  match name { "rust" => … }, returns (fn(&Vec<FrozenUnit>) -> String, ext).
• core/src/codelib_gen/rust.rs — generate_rust: structs, enums, trait for
  protocols. Synchronous, in-process, no versioning.
• ComlineProject/generation — code_gen / lib_gen / rust_c_ffi /
  rust_abi_stable scaffolding, pre-CAS, does not build against current core.
• No dynamic loading, no ABI boundary, no discovery, no supports_version.

Technical Challenge

Rust doesn't have a stable ABI by default. Possible solutions:

1. Use C ABI wrapper (traditional approach)
2. Use abi_stable crate (Rust-to-Rust stable ABI)
3. Use process-based plugins (spawn external process)
4. WebAssembly plugins (WASM runtime)

Need to research and decide on approach.

Acceptance Criteria

• Plugin API defined with stable ABI
• Dynamic library loading works cross-platform
• Plugin discovery from standard paths (~/.comline/plugins/, ./plugins/)
• Version compatibility enforcement
• At least 2 reference generators implemented:
  • Rust generator (structs, enums, traits)
  • TypeScript generator (interfaces, types)
• Plugin development guide written
• Example third-party plugin works

Tasks

• Research stable ABI solutions (compare approaches)
• Design plugin interface (trait definitions)
• Implement dynamic library loading (using libloading or similar)
• Create plugin registry/discovery system
• Add version checking and compatibility validation
• Migrate / rebuild the ComlineProject/generation generators against
  current core (code_gen text + lib_gen crate/dylib).
• Build reference Rust generator (extend codelib_gen::rust):
  • Generate Rust structs from schema structs
  • Generate Rust enums from schema enums
  • Generate trait definitions from protocols
  • Emit cross-schema imports as use (currently dropped)
• Build reference TypeScript generator:
  • Generate TS interfaces
  • Generate type definitions
  • Generate RPC client stubs
• Write plugin development guide
• Add plugin testing infrastructure
• Document plugin system architecture

Plugin Interface (Draft)

pub trait Generator {
    fn name(&self) -> &str;
    fn version(&self) -> &str;
    fn supports_version(&self, ir_version: &str) -> bool;
    fn generate(&self, frozen_units: &[FrozenUnit]) -> Result<String>;
}

Dependencies

• Consolidate and Complete IDL Parser #3 IR Compilation (needs complete FrozenUnits)

Blocks

None

[Kinflou]

Body updated: core/src/codelib_gen/{mod,rust}.rs is a real (if minimal, hardcoded, synchronous) rust generator now, not a todo!(). The older code_gen/lib_gen/rust_abi_stable design in ComlineProject/generation is unmigrated (imports removed basic_storage) and reviving it is part of this issue. The consumer comline.toml [generate] mode = code|lib|dylib sits on top of this.