[HC-016] Hard cutover CMake and build graph to the new module tree

[doublemover]

Hard cutover policy: the build graph matches the new ownership tree exactly. No stale monolithic comments, no catchall compiler target, no old source files compiled through alias targets, no oversized source file accepted by build lint.

Source facts already established:

• native/objc3c/CMakeLists.txt contains stale text describing a monolithic src/main.cpp state.
• Current CMake already defines split libraries, while the source files remain oversized.
• Source-size limits are not enforced by the build.

Required build tree:

• native/objc3c/CMakeLists.txt: project setup and top-level add-subdirectory calls only.
• native/objc3c/cmake/
  • Objc3CompilerOptions.cmake
  • Objc3Module.cmake
  • Objc3SourceSizeGate.cmake
  • Objc3Sanitizers.cmake
  • Objc3Platform.cmake
• native/objc3c/src/CMakeLists.txt: module target wiring.
• Per-module CMakeLists.txt files under:
  • ast/
  • config/
  • lex/
  • parse/
  • sema/
  • lower/
  • ir/
  • runtime/
  • pipeline/
  • artifacts/
  • io/
  • support/
  • driver/
  • tools/

Required target families:

• objc3c_support_*
• objc3c_io_*
• objc3c_ast_*
• objc3c_config
• objc3c_lex
• objc3c_parse_*
• objc3c_sema_*
• objc3c_lower_*
• objc3c_ir_*
• objc3c_runtime_*
• objc3c_pipeline_*
• objc3c_artifacts_*
• objc3c_driver
• objc3c_frontend_c_api
• objc3c_tools_*

Required work:

• Replace the top-level native CMake file with a small orchestration file.
• Add one CMake module helper for declaring Objective-C 3.0 compiler modules.
• Add source-size gate integration that fails any native source file over 1,500 lines and any native model header over 1,000 lines.
• Compile each ownership module as its own target.
• Link dependencies according to the ownership tree.
• Delete target aliases for old module names.
• Delete stale architecture comments and old monolithic state text.

Maximum effort shared hoist pass:

• Hoist shared compiler options to Objc3CompilerOptions.cmake.
• Hoist platform-specific settings to Objc3Platform.cmake.
• Hoist source-size checks to Objc3SourceSizeGate.cmake.
• Hoist sanitizer flags to Objc3Sanitizers.cmake.

Acceptance criteria:

• rg "monolithic|src/main.cpp state|planned steady-state|alias target|compat" native/objc3c/CMakeLists.txt native/objc3c/cmake native/objc3c/src returns no stale build commentary or old target alias.
• CMake config fails on oversized source files.
• Ninja or MSBuild target names mirror the module tree.
• Native build passes after the split.

[doublemover]

Current checkout evaluation after the hard-cutover integration commits: PARTIAL, keep open.

Landed work:

• Native build passed after the integration checkpoint.
• The strict dependency-boundary check passes.
• A current native source-size audit found no native/objc3c/src .cpp, .h, or .inc file over 1,500 lines.

Remaining blockers from the current checkout:

• The build graph still compiles phase wrappers that include .inc part shards for parser, sema, IR, and runtime.
• The CMake/module graph therefore does not yet fully match real owned module translation units.
• Final build-graph closure should include a gate that fails reintroduced include-shard monoliths, not just overlarge physical files.

This should close after the module tree is represented directly in CMake and the old include-part structure is gone.

[doublemover]

Checkpoint pushed: ac31f1519.

Build graph progress:

• Added the sema parser-handoff headers to the objc3c_sema target in native/objc3c/CMakeLists.txt.
• Removed the active objc3_parser_sema_handoff_scaffold_parts include-part dependency by promoting the contract/scaffold content into named headers.
• Verified the sema target builds with the updated target ownership.

Validation:

• cmake --build tmp/build-objc3c-native --target objc3c_sema --parallel PASS
• rg -n "objc3_parser_sema_handoff_scaffold_part_|objc3_parser_sema_handoff_scaffold_parts" native/objc3c/src native/objc3c/CMakeLists.txt returned no matches
• npm run objc3c -- lint PASS

Keeping this open. This is one target-family cleanup, not the full CMake/module-family cutover for all parser, sema, lower, IR, runtime, artifacts, support, and IO ownership families.

[doublemover]

Additional build-graph checkpoint pushed: 7e7f5d762.

CMake/module ownership progress:

• objc3c_pipeline now owns objc3_typed_sema_to_lowering_contract_surface_core.h and objc3_typed_sema_to_lowering_contract_surface.h directly.
• The old objc3_typed_sema_to_lowering_contract_surface_parts/*.inc shard path is gone from the active tree.
• The first attempted one-header fold hit the actual CMake source-size gate, which enforces a 1,000-line header cap; the final split keeps the headers at 644 and 821 lines.

Validation:

• cmake --build tmp/build-objc3c-native --target objc3c_pipeline --parallel PASS
• python -m scripts.source_hygiene PASS
• git diff --check HEAD PASS

Keeping this open. This advances one pipeline header family; the broader CMake target-family split remains open.

[doublemover]

Build graph/source-size checkpoint (May 6, 2026): landed and pushed 893a4af12.

Completed in this checkpoint:

• Removed the objc3_objc3_path_parts include-shard wrapper files.
• Added real driver source ownership in native/objc3c/src/driver/objc3_objc3_conformance_path.cpp.
• Updated native/objc3c/CMakeLists.txt so the driver target compiles the new real source file directly.
• Kept objc3_objc3_path.cpp at the 1500-line source-size gate and moved conformance publication path logic into a 295-line source file.

Validation evidence:

• CMake configure passed with the source-size gate: cmake -S native\\objc3c -B tmp\\objc3c-worker2-build -DOBJC3C_ENABLE_LLVM_DIRECT_OBJECT_EMISSION=OFF.
• Direct MSVC compile passed for both converted driver files.
• rg "objc3_objc3_path_parts|objc3_objc3_path_part_" native\\objc3c found no remaining references.
• git diff --cached --check PASS.

Current closure status: still open. Other parser/sema/IR/runtime include-shard wrapper families remain.

[doublemover]

Build graph/source-size parser checkpoint (May 6, 2026): landed and pushed 3b05a1a8f.

Completed in this checkpoint:

• Added real parser module files for message-send profile helpers and wired them into native/objc3c/CMakeLists.txt.
• Reduced the parser include shard by moving helper implementation into the new source/header pair.

Validation evidence:

• cmake --build tmp/worker10-objc3c-parse-build --target objc3c_parse PASS.
• git diff --cached --check PASS.
• python -m scripts.source_hygiene PASS, active_findings 0.

Current closure status: still open. This is one parser helper slice; other include-shard wrapper families remain.

[doublemover]

Build graph/source-size checkpoint (May 6, 2026): landed and pushed 1455128eb.

Completed in this checkpoint:

• Added real sema module files for block-handoff equivalence helpers and wired them into native/objc3c/CMakeLists.txt.
• Reduced the sema pass-manager include shard by moving the helper family into the new source/header pair.

Validation evidence:

• cmake --build tmp/worker14-sema-build --target objc3c_sema PASS.
• git diff --cached --check PASS.
• python -m scripts.source_hygiene PASS, active_findings 0.

Current closure status: still open. More parser/sema/IR include-shard families remain.

[doublemover]

Pushed checkpoint 7b2c532. The new lower/core source is registered in native/objc3c/CMakeLists.txt under objc3c_lower, and the build-graph audit verified CMake configure plus objc3c_lower build. No source/header size-limit violation was found for this slice. #8147 remains open because target wiring is still mostly top-level; the next active worker owns a bounded lower-local CMake split.