Legacy default parity

This is the executable specification for issue #179. The rows live in symfonic.migration.LEGACY_DEFAULT_ROWS; tests/migration/test_legacy_defaults.py pins that every legacy field is present and that each one has either a same-turn legacy/native comparison or an existing owner.

FrameworkConfig defaults do not all start work. “Inert” means the field does not independently run a behaviour; it is recorded here so an adopter does not try to recreate a behaviour that the legacy agent did not run.

Legacy field or active companion	Trigger	Kernel composition / result	Evidence or owner
auto_hydrate	bound store and scope	candidate: memory_capabilities + PromptingCapability	gap, #188: native-only test
auto_consolidate	MemoryExtractorPort	candidate: memory_capabilities(..., extractor=...)	gap, #185: native-only test
spreading_activation	AssociationSource	candidate: SpreadingActivation through memory factory	gap, #188: native-only test
lazy_tooling	HMS prompt, procedural skills, tools	gap with memory composed. With no store and no memory row it cannot activate: compose_legacy_defaults composes nothing for it, and the agent offers every registered tool, as legacy does there. A SymfonicAgent host with this input is served by the kernel only with no procedural layer and enable_hms_prompt=False; either one keeps the turn on legacy.	#185; storeless: CORE-20 native differential
enabled_layers	memory retrieval	candidate: default RetrievalPolicy	gap, #188: default-value comparison only
skill_auto_approve	promotable skill in SymfonicAgent	proposed native change: Agent does not read this legacy setting; native procedures are drafts pending explicit review. The FP-5 contract has not approved this row, and the legacy reader remains live.	ProceduralLayer review journey / CORE-36
streaming_enabled	always	Agent.stream()	verified: same-turn deterministic stream completes on both paths
experimental_tool_decorator	never	retained no-op; @symfonic_tool is unconditional	config source
phase_12_action_type_from_tool_calls	phase-12 extraction	gap	#185
messages_cache_policy	legacy React node plus an Anthropic cache dialect	approved change: stock native history remains unmarked; callers can compose an explicit Anthropic history opt-in with one completed-boundary marker. It does not reproduce automatic selection or the rolling ladder.	native cache composition, two-turn Anthropic wire capture
manifest_cache_position	legacy stratigraphic tool-manifest path	gap: public L1/L2 regions and #221's explicit native manifest opt-in do not reproduce legacy selection or make this retired setting accepted.	region wire capture, #179, #221
system_prefix_cache_ttl	compatible provider cache	gap	#187
tool_result_recall_mode	tool-result history	gap	#188
activation_log_mode	activation runs	gap	#188
prompt_layer_mode	legacy prompt path	gap	#187
hms_budget_mode	HMS prompt assembly	gap	#187
memory_extract_cadence	every turn; default 1	no prompt-cadence consumer	gap, #187
entity_linker_extractor	enable_entity_linker=True	inactive until that flag	#186
nightly_nap_cron	never	operator recommendation, not engine scheduling	config source
phase_12_llm_model	LLM phase-12 extraction	gap	#185
otel_service_name	otel_enabled=True and an OTEL sink	inactive until OTEL is composed	#191
working_memory_recent_turns	ConversationSource	candidate: memory factory conversation=/recent_turns=	gap, #188: native-only test
quick_nap_interval	ConsolidationCoordinator	candidate: memory factory consolidation=	gap, #185: native-only test

The verified subset contains only streaming. It deliberately has no memory, prompting, retrieval, write, or consolidation stages:

from symfonic.migration import SUPPORTED_DEFAULT_BEHAVIORS, compose_legacy_defaults

agent = compose_legacy_defaults(
    provider,
    behaviors=SUPPORTED_DEFAULT_BEHAVIORS,
)

The runnable import-shaped example is examples.migration_parity.composed_defaults.build_agent. A bare compose_legacy_defaults(provider) reports every unresolved field and all missing deployment dependencies in one error. Neither outcome means issue #179 is ready to close.