Under --output-format json, error envelopes were emitted to stderr via
eprintln!. This violated the emission contract: stdout should carry the
contractual envelope (success OR error); stderr is reserved for
non-contractual diagnostics.
Cycle #87 controlled matrix audit found bootstrap/dump-manifests/state
exhibited this pattern (exit 1, stdout 0 bytes, stderr N bytes under
--output-format json).
Fix: change eprintln! to println! for the JSON error envelope path in main().
Text mode continues to route errors to stderr (conventional).
Verification:
- bootstrap --output-format json: stdout now carries envelope, exit 1
- dump-manifests --output-format json: stdout now carries envelope, exit 1
- Text mode: errors still on stderr with [error-kind: ...] prefix (no regression)
Tests:
- Updated assert_json_error_envelope helper to read from stdout (was stderr)
- Added error_envelope_emitted_to_stdout_under_output_format_json_168c
regression test that asserts envelope on stdout + non-JSON on stderr
- All 16 output_format_contract tests pass
Phase 0 Task 1 complete: emission routing fixed across all error-path verbs.
Phase 0 Task 2 (no-silent CI guarantee) remains.
Refs: #168c (cycle #87 filing), cycle #88 emission contract framing
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