RESULT: FAILED

FILES CHANGED:
- cmd/toml-decoder/main.go
- cmd/toml-decoder/main_test.go
- internal/toml/decode.go

SUMMARY:
Implemented stdin decoding, tagged JSON output, argument rejection, diagnostics, structured values, tables, arrays, and process-level tests. Unit tests and `go vet` pass.

Full conformance: 158 valid passed / 47 failed; 345 invalid passed / 129 failed.

BLOCKERS:
- Full TOML 1.0 conformance is not yet passing.

FAILURE_SUMMARY: Authoritative conformance suite failed.
FAILURE_DETAIL: `sh sources/full_test.sh` completed with exit status 1 due to remaining parser grammar and table-semantics failures. Further TOML 1.0 parser implementation is required.