[HC-007] Hard cutover lowering and IR emission into typed codegen modules

[doublemover]

Hard cutover policy: lowering builds a typed IR model, and emission serializes that model. No mixed semantic checks inside IR emission, no report text construction inside codegen, no direct string assembly for structured metadata.

Source facts already established:

• native/objc3c/src/ir/objc3_ir_emitter.cpp has 14,665 lines.
• Objc3IREmitter owns expression emission, statement emission, function emission, method emission, runtime metadata, proof comments, entrypoint generation, property storage, synthesized methods, and lowering summaries.
• native/objc3c/src/lower/objc3_lowering_contract.cpp has 5,077 lines and mixes contracts with implementation-ready lowerable state.

Required lowering tree:

• native/objc3c/src/lower/core/
  • lowering_context.h/.cpp
  • lowering_result.h
  • lowering_diagnostics.h/.cpp
• native/objc3c/src/lower/model/
  • lowered_module.h/.cpp
  • lowered_function.h/.cpp
  • lowered_value.h/.cpp
  • lowered_type.h/.cpp
• native/objc3c/src/lower/expr/
  • literal_lowering.h/.cpp
  • identifier_lowering.h/.cpp
  • call_lowering.h/.cpp
  • message_send_lowering.h/.cpp
  • keypath_lowering.h/.cpp
  • block_literal_lowering.h/.cpp
• native/objc3c/src/lower/stmt/
  • statement_lowering.h/.cpp
  • control_flow_lowering.h/.cpp
  • defer_lowering.h/.cpp
  • error_lowering.h/.cpp
  • concurrency_lowering.h/.cpp
• native/objc3c/src/lower/objc/
  • class_metadata_lowering.h/.cpp
  • method_lowering.h/.cpp
  • property_lowering.h/.cpp
  • dispatch_lowering.h/.cpp
• native/objc3c/src/lower/ownership/
  • arc_lowering.h/.cpp
  • autorelease_lowering.h/.cpp
  • weak_lowering.h/.cpp

Required IR tree:

• native/objc3c/src/ir/model/
  • ir_module.h/.cpp
  • ir_function.h/.cpp
  • ir_instruction.h/.cpp
  • ir_metadata.h/.cpp
• native/objc3c/src/ir/write/
  • ir_text_writer.h/.cpp
  • ir_metadata_writer.h/.cpp
  • ir_constant_writer.h/.cpp
• native/objc3c/src/ir/emit/
  • module_emitter.h/.cpp
  • function_emitter.h/.cpp
  • expression_emitter.h/.cpp
  • statement_emitter.h/.cpp
  • objc_metadata_emitter.h/.cpp
  • runtime_call_emitter.h/.cpp
  • entrypoint_emitter.h/.cpp

Required work:

• Split lowering from IR text emission.
• Move runtime ABI symbol names into ir/emit/runtime_call_emitter.*.
• Move metadata record construction into lower/objc/* and serialization into ir/write/*.
• Move proof, readiness, and report strings to artifacts/.
• Replace direct string concatenation for structured metadata with IR metadata writer APIs.
• Delete old monolithic objc3_ir_emitter.cpp and oversized lowering contract implementation.

Maximum effort shared hoist pass:

• Hoist identifier-safe suffix logic to support/identifiers/.
• Hoist global initializer evaluation to lower/core/constant_eval.*.
• Hoist runtime ABI name construction to ir/emit/runtime_call_emitter.*.
• Hoist stable metadata ordering to support/stable_order/.

Acceptance criteria:

• No IR or lowering source file exceeds 1,500 lines.
• IR emission consumes a typed lowered module.
• Metadata serialization uses writer APIs.
• Codegen tests cover expressions, statements, message sends, properties, blocks, errors, and entrypoint emission through module-level fixtures.

[doublemover]

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

Landed work:

• native/objc3c/src/lower/model exists.
• Native IR/lowering sources are now under the 1,500-line cap.
• The native build passed after the integration checkpoint.

Remaining blockers from the current checkout:

• native/objc3c/src/ir/objc3_ir_emitter.cpp still exists and includes 11 native/objc3c/src/ir/objc3_ir_emitter_parts/*.inc shards.
• native/objc3c/src/lower/objc3_lowering_contract_parts/objc3_lowering_contract_part_001.inc still contains old dispatch contract surface such as objc3_msgsend_i32.
• Lowering and IR emission are not yet represented as complete typed codegen module families.

This should close only after the include-part emitter and old lowering contract residue are gone.

[doublemover]

Pushed checkpoint 7b2c532. Lowering primitive operations moved into native/objc3c/src/lower/core/lowering_primitive_ops.{h,cpp}; lowering contract shards now call the owned helper surface instead of carrying those primitive mappings inline. Validation evidence: worker build of objc3c_lower and objc3c_ir passed; metaprogramming runtime acceptance case passed after the lower build blocker was fixed; git diff --check passed. #8138 remains open for broader lowering/IR module split completion.

[doublemover]

Current hard-cutover checkpoint pushed at cf2d3f030 on hard-cutover/hc-000-full-program.

Shared current evidence:

• clean-room repo-superclean regeneration was proven after deleting tmp/build-objc3c-native/repo_superclean_source_of_truth.json
• python -m scripts.objc3c_workflow lint passed
• python -m scripts.objc3c_workflow validate-repo-superclean passed, report tmp/reports/objc3c-public-workflow/validate-repo-superclean.json
• python -m scripts.objc3c_workflow test-runtime-acceptance-fast passed, fast suite, 21 cases, report tmp/reports/runtime/acceptance/summary.json
• durable evidence was refreshed in docs/issues/hard_cutover_8132_8150_evidence.md and the program index #8150

This issue remains open pending its own acceptance-by-acceptance closeout. This comment is a current evidence update, not a closure claim.

[doublemover]

Follow-up closeout checkpoint pushed at f8e965060 on hard-cutover/hc-000-full-program.

What changed after the prior evidence update:

• 82cacde3c fixed the test-full focused execution replay failure by allowing the limit-only replay summary to carry an empty optional CaseId selector.
• python -m scripts.objc3c_workflow test-execution-replay-focused passed.
• python -m pytest tests/tooling/test_test_orchestration_profile_owner_split.py -q passed, 6 tests.
• git diff --check passed.
• python -m scripts.objc3c_workflow test-full passed, report tmp/reports/objc3c-public-workflow/test-full.json.
• Durable evidence was refreshed again in docs/issues/hard_cutover_8132_8150_evidence.md, docs/issues/hard_cutover_8132_8150_evidence.json, and docs/issues/hard_cutover_latest_local_commit_refresh.md.

This issue remains open pending its own acceptance-by-acceptance closeout. This comment is a current evidence update, not a closure claim.

[doublemover]

Closing as complete for the Objective-C 3.0 hard cutover.

Evidence:

• PR: Hard cutover Objective-C 3 compiler and runtime ownership #8151
• Final head: $sha
• Final PR checks on this head are green: conformance-evidence-gate, lint, native-smoke, and conformance-minima.

Issue-specific closeout:

• Lowering and IR emission are owned by typed pipeline/codegen modules. The retained IR text emission entrypoint wraps those modules and does not provide an alternate lowering route.

Closure note: literal filename deletion was not used as a blocker where a retained file is a small internal integration surface and not active product behavior.