[Inference/Web] Pipeline decompile stage returns TAC instead of generated Solidity

[agorevski]

Finding

The programmatic pipeline's DECOMPILE stage is documented/configured as bytecode-to-Solidity, but it currently returns TAC and ignores the configured model path.

Evidence

• PipelineConfig exposes decompiler_model_path, but initialize() never creates SmartContractDecompiler or uses that path: src/pipeline_orchestrator.py:31-44, src/pipeline_orchestrator.py:107-135.
• _run_decompilation() calls analyze_bytecode_to_tac() and stores the TAC string in result.decompiled_source: src/pipeline_orchestrator.py:203-211.
• E2E coverage only checks decompiled_source is not None, so TAC can pass as "decompiled" output: tests/test_e2e.py:190-196.

Impact

API/SDK callers can believe they received Solidity when they actually received intermediate TAC. Audit/report flows built on this result can present misleading output and make inference reliability hard to reason about.

Recommended fix

Instantiate and use SmartContractDecompiler when the decompile stage is enabled and a model path is configured. Return separate structured fields for TAC, generated Solidity, model status, and errors; fail or warn explicitly when no model is available.

Acceptance criteria

• PipelineStage.DECOMPILE uses model-backed decompile_contract() when decompiler_model_path is set.
• TAC and Solidity are separate fields in PipelineResult/to_dict().
• Missing model paths produce an explicit stage failure or decompilation_status, not TAC in decompiled_source.
• Tests assert that model-backed decompile returns Solidity-shaped output and that TAC-only fallback is clearly labeled.

[agorevski]

Resolved in commit e4a1530. Validation: python -m compileall -q train.py download_hf_contracts.py src web scripts tests; uv run pytest -q (521 passed).