Quickstart: Dead-Port Disposition

Verify the defect exists (before implementing)

# Both greps should hit today; the mission removes both.
grep -n "flush(ctx.sync_emitter)\|sync_emitter=ctx.sync_emitter" src/runtime/next/runtime_bridge.py
# Two classes, one name:
grep -rn "^class RuntimeEventEmitter" src/runtime/next/

Implement in dependency order

1. Seam (Concern A) — edit src/runtime/next/_internal_runtime/events.py: add NullEmitter.for_mission, NullEmitter.seed_from_snapshot, runtime_emitter_for_mission, register_runtime_emitter_factory, reset_runtime_emitter_factory; extend __all__; mirror in _internal_runtime/emitter.py. 2. Red-first tests (Concern D) — create tests/runtime/test_bridge_decision_log_flush.py; run it and confirm tests F1 and F2 are red: ``bash .venv/bin/pytest tests/runtime/test_bridge_decision_log_flush.py -q -p no:cacheprovider ` 3. Flush fixes (Concern C) — runtime_bridge.py:2187 and :1976 → ctx.emitter_for_engine; add DecisionGitLog.seed_from_snapshot. Re-run step 2: all green. 4. Bridge rewiring + delete (Concern B) — swap the import at runtime_bridge.py:195; replace RuntimeEventEmitter.for_feature( at :1552 and :2739 with runtime_emitter_for_mission(; fix runtime_bridge_engine.py:80; git rm src/runtime/next/event_emitter.py; update tests/specify_cli/events/test_decision_log_coord.py:17. 5. Rewrites + guard (Concern E) — patch the factory name at the 14 sites listed in plan.md; add factory/registry tests to tests/next/test_internal_runtime_coverage.py; add tests/architectural/test_runtime_emitter_seam.py. 6. Docs + CHANGELOG (Concern F) — docstring, two conformance comments, one ### Fixed` line.

Verify

make test-fast
.venv/bin/pytest tests/runtime/ tests/next/ tests/specify_cli/next/ tests/specify_cli/events/ -q -p no:cacheprovider
.venv/bin/pytest tests/status/test_producer_conformance.py tests/contract/test_identity_contract_matrix.py -q -p no:cacheprovider
.venv/bin/pytest tests/architectural/test_layer_rules.py tests/architectural/test_no_legacy_terminology.py tests/architectural/test_runtime_emitter_seam.py -q -p no:cacheprovider
.venv/bin/ruff check . && .venv/bin/mypy src/runtime/next/_internal_runtime/events.py src/specify_cli/events/decision_log.py

Expected after completion: both greps in "Verify the defect" return nothing; exactly one class RuntimeEventEmitter; all suites green; ruff and mypy clean.

Record in the PR

Commands and passed/failed counts for every line above; the added-lines terminology grep (feature identifiers: 0); retired-surface scan: 0 hits.