refactor(storage): remove branch-added database migration machinery

Fresh V2 stores are created at their final schema; nothing on disk
predates this branch, so every migrate-old-to-new path the branch added
was dead weight and the source of live failures: the unbounded
observation-projection retry spin, 30s migration-txn aborts under the
150K-chunk vector rewrite, and a format-revision skew that silently
disabled retention.

Removed: the observation projection V1-to-V4 migration, its silent
full-rebuild fallback and the worker's advance pass (creation now
installs the final V4 shape and any other shape is refused typed with a
fresh-start remedy); the legacy inline-vector payload migration and its
rebuild receipts (stores are born row-per-vector; the liveness
inventory read path survives); the legacy memory cutover drains, V1
feedback-history repair and backfill pipeline plus their scheduler
drains and the memory-cutover CLI verb (the archive-merge half stays -
branch retirement still preserves memory through it); session-temporal
repair; the transcript-facts drain driver; Ladder B stepwise
convergence. Fresh-store schema verified byte-identical to all live
stores minus the empty migration ledger. memory_status loses
legacy_backfill_complete, which could never complete again.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: ScriptedAlchemy

crates/tracedecay-dashboard-api/src/memory_api.rs

@@ -276,7 +276,6 @@ async fn memory_status_payload(state: &DashboardState) -> Result<MemoryStatusPay
         helpful_count: as_usize(typed_status.helpful_count())?,
         unhelpful_count: as_usize(typed_status.unhelpful_count())?,
         missing_vector_count: as_usize(typed_status.missing_vector_count())?,
-        legacy_backfill_complete: typed_status.legacy_backfill_complete(),
         repair: MemoryRepairStats {
             missing_vectors_repaired: as_usize(typed_status.repair().missing_vectors_repaired())?,
             banks_rebuilt: as_usize(typed_status.repair().banks_rebuilt())?,

crates/tracedecay-global-db/src/lib.rs

@@ -16,7 +16,6 @@ pub mod observation;
 mod observation_adapter;
 mod observation_projection;
 mod registered_maintenance;
-mod session_temporal_repair;
 mod support;
 pub use observation_adapter::GlobalDbObservationStore;
 pub use observation_projection::{project_observation_with_engine, rebuild_projection_with_engine};
@@ -83,14 +82,6 @@ pub use api_types::{
     StoreArtifactRecord, StoreArtifactUpsert, StoreInstanceRecord, StoreInstanceUpsert,
     TranscriptBatch,
 };
-#[cfg(test)]
-use session_temporal_repair::connection_table_exists;
-pub use session_temporal_repair::{
-    SessionTemporalRepairOutcome, SessionTemporalRepairStage,
-    advance_required_session_temporal_state_repair, advance_session_temporal_store_repair,
-    advance_session_temporal_store_repair_with_page_rows, enqueue_session_temporal_store_repair,
-    repair_session_temporal_store, session_temporal_store_repair_status,
-};
 pub use support::{
     AccountingMode, env_flag, env_value_truthy, estimate_tokens, global_accounting_enabled,
     global_accounting_mode, global_db_path, global_db_path_is_overridden,
@@ -115,7 +106,3 @@ mod checkpoint_tests;
 #[cfg(any(test, feature = "test-helpers"))]
 #[allow(clippy::unwrap_used, clippy::expect_used)]
 pub mod tests;
-
-#[cfg(test)]
-#[allow(clippy::unwrap_used, clippy::expect_used)]
-mod session_temporal_repair_tests;