[EPIC] Phase 5: retire the frozen competing implementations (321 modules)

[jeremymanning]

Tracking issue for the consolidation the product contract set up but deliberately did not perform.

Current state

find src/orchestrator -name "*.py" | wc -l → 321

docs/adr/0001-product-contract.md names the canonical compiler, executor and registry and freezes the competitors, but the frozen implementations are all still shipped in the wheel. Naming a canonical path was the prerequisite; removing the alternatives is the work.

Why it was not done in one pass

Deleting competing implementations without contract tests characterising their behaviour is exactly the failure mode that produced this situation — successive incompatible rewrites, each declared complete. The ADR path is deliberate: name the canonical route, add contract tests, then remove alternatives incrementally, each removal justified by a passing test.

Known members of the frozen set

• Compiler variants, including SkillsCompiler / EnhancedSkillsCompiler, which the another total refactor #426 audit found orphaned — unreachable from orchestrator run, referenced only by a re-export and one test that fails at collection
• Multiple executors/engines, state managers, model registries, tool registries, condition systems, validation frameworks

Approach

1. Start from the ADR "off the import closure" list — those are removable without touching the working path
2. Add a contract test pinning the canonical behaviour before each removal
3. One removal per PR, with the wheel module count in the description

Blocked on / related to: #426 (product direction), #429 (adapter layers), #354 (test suite health).

Acceptance criteria

• Each removal is justified by a passing contract test
• The wheel ships one compiler, one executor, one registry of each kind
• Module count trends down and is reported per PR