MCP bootstrap RecursionError constructing selective-retirement request schema #528

Actual fresh scientific target04 stopped before any native/viewer/science work: full MCP build_server raised RecursionError, exposing only its two bootstrap diagnostic tools. Correct installed engineering reproduction explicitly selects target04 and calls original build_server; trace: GeneratedMcpViewerRequestToolBinding -> canonical DTO factory expected_producers dict[str,list[dict[str,JsonValue]]] -> FastMCP create_model -> Pydantic unbounded expansion of the implicit recursive alias. Original scientific failure and the separate source-import shadow failure are retained; no uncertain operation is replayed.

Owner: Planck combined package integration, coordinated with Singer #522. Fix at canonical request declaration using the existing nine-field StreamProducerIdentity and its original from_payload decoder. No Any, alternate schema/registry, timeout or recursion-limit increase. Plain dataclass schema construction alone is insufficient: retain original required/optional string normalization, int/bool coercion and unknown-key admission semantics. Acceptance: actual new ordinary whole installed package, full MCP construction/list/health, original-decoder equivalence through actual SDK, then detached public archive/retirement receiving before merge or fresh SCI release. Frozen target04 must not be patched. #522 is the working implementation PR; #524/#494 receiving boundaries remain distinct. Prior 49 installed receiver checks missed server construction.