trail-mate/docs/audits/PHASE12_FALLBACK_DELETION_READINESS.md

Phase 12 Fallback Deletion Readiness

Purpose

Phase 12 does not delete fallback by default. It records which fallback surfaces are now fallback-only, which alias surfaces are compatibility-only, and what must be true before deletion.

Readiness Ledger

Surface	Current status	Primary path replacement	Safe to delete now?	Why / why not	Deletion condition	Owner	Checker status
LinuxSim hardcoded runtime routing	fallback-only	LinuxSimRuntimeRenderer -> AsciiDescriptorRenderer -> AsciiRuntimeEntryAdoption	No	fallback smoke still proves failed-adoption behavior and the real simulator renderer has not removed every hardcoded route dependency	fallback smoke no longer needed and real simulator entry has no direct hardcoded route dependency	apps/linux_sim_shell	check_phase10_primary_path_ready.py, check_phase11_renderer_consumption_ready.py
GTK hardcoded page registry	fallback-only	LinuxUConsoleGtkPageRegistryRenderer -> GtkDescriptorPageRegistry -> GtkRuntimeEntryAdoption	No	real GTK widget/page creation still needs a compatibility page registry path	real GtkWidget page creation consumes GtkDescriptorPage as the primary page source	apps/linux_uconsole_gtk	check_phase10_primary_path_ready.py, check_phase11_renderer_consumption_ready.py
LVGL hardcoded menu/page creation	fallback-only descriptor fallback	LvglDescriptorRendererProbe -> LvglDescriptorMenuModel -> LvglPrimaryScreenGraphRuntime	No	real LVGL menu/page renderers have not consumed LvglDescriptorMenuModel on a concrete target	one real LVGL target consumes LvglDescriptorMenuModel before menu/page object creation	modules/ui_lvgl_ux_packs	check_phase10_primary_path_ready.py, check_phase11_renderer_consumption_ready.py
Chat legacy alias headers	deprecated alias only	ChatDeliveryActionPortAdapter, ChatDeliveryEventProjectionAdapter	No	compatibility alias tests and possible downstream includes still define the deletion window	no downstream includes of LegacyChatDeliveryActionBridge or LegacyChatDeliveryEventBridge remain	modules/ui_chat_runtime	check_phase9_legacy_burndown_ready.py
KeyVerification legacy alias headers	deprecated alias only	KeyVerificationPresentationSource, KeyVerificationActionSink, KeyVerificationSessionAdapter	No	compatibility alias tests and possible downstream includes still define the deletion window	no downstream includes of LegacyKeyVerificationSource, LegacyKeyVerificationActionSink, or LegacyKeyVerificationSession remain	modules/ui_key_verification_runtime	check_phase9_legacy_burndown_ready.py
MapOverlay legacy alias header	deprecated alias only	MapOverlaySnapshotSource, MapOverlayProjectionAdapter	No	compatibility alias tests and possible downstream includes still define the deletion window	no downstream includes of LegacyMapOverlaySource remain and map renderers consume stable snapshots only	modules/ui_map_runtime	check_phase9_legacy_burndown_ready.py
ui_shared forwarding shims	deprecated forwarding shims only	stable runtime module headers	No	they protect old include paths while downstream references burn down	no production or downstream include path uses ui/presentation_sources/legacy_*	modules/ui_shared	check_phase9_legacy_burndown_ready.py
legacy/app_implementations roots	historical implementation roots only	final app shells plus stable modules	No	roots still provide transitional build/runtime compatibility	final app shells and stable modules own all runtime behavior and builds no longer need historical roots	legacy/app_implementations	check_phase8_layout_ready.py, check_post_refactor_final_ready.py

Deletion Rule

Fallback deletion must be a targeted debt task, not a new architecture phase. Every deletion needs:

• primary path evidence
• fallback smoke update or removal
• downstream include search
• checker update
• concrete owner

Current Decision

No fallback or deprecated alias is deleted in Phase 12. Phase 12 records deletion readiness and freezes the guardrails that prevent fallback from becoming a primary path again.