diff --git a/CONTEXT.md b/CONTEXT.md
index 7a79d1c..4bdd7ba 100644
--- a/CONTEXT.md
+++ b/CONTEXT.md
@@ -74,6 +74,20 @@ See [ADR-0001](./docs/adr/0001-bulk-upload-state-machine.md) for the deliberate
 - A **BulkUpload** has at most one **Task** (the orchestration handle for the FastAPI pipeline run); a Task has many **SubTasks** (one per pipeline stage: address matching, combiner).
 - A **Portfolio** has many **VocabularyMappings** — one row per `(category, description)` it has ever encountered across all its BulkUploads. See [ADR-0002](./docs/adr/0002-landlord-override-vocabulary.md).
 
+### Baseline performance
+
+**Lodged performance**:
+The SAP score, EPC band, CO₂ emissions, and primary energy intensity as submitted to the government EPC register. Ground truth from the register; never modified.
+_Avoid_: original performance, registered performance
+
+**Effective performance**:
+The SAP score (and associated metrics) that the modelling engine actually uses as its baseline. Usually equals Lodged performance, but differs when a Landlord override or data-quality issue makes the lodged certificate unreliable — triggering a Rebaseline.
+_Avoid_: current performance, adjusted performance
+
+**Rebaseline**:
+The act of substituting a corrected set of performance metrics in place of the Lodged values. Recorded on `property_baseline_performance` with a `rebaseline_reason` enum value: `none`, `pre_sap10`, `physical_state_changed`, or `both`.
+_Avoid_: override, adjustment, correction
+
 ## Example dialogue
 
 > **Dev:** "If the **Combiner** finishes but the user hasn't clicked Finalise, what does the user see?"
diff --git a/backlog/drizzle-schema-handoff.md b/backlog/drizzle-schema-handoff.md
index 4308465..0cbf28c 100644
--- a/backlog/drizzle-schema-handoff.md
+++ b/backlog/drizzle-schema-handoff.md
@@ -1,6 +1,6 @@
 # Drizzle schema handoff — pending EPC migrations
 
-**Task:** Update Drizzle table definitions in `src/app/schema/property.ts` to match the
+**Task:** Update Drizzle table definitions in `src/app/db/schema/property.ts` to match the
 Python SQLModel definitions. Do **not** run `drizzle-kit generate` or any migration
 commands — the developer will run generation manually after your changes.
 
@@ -9,6 +9,27 @@ Two sets of changes are covered here:
 1. EPC property round-trip fidelity gaps (fixes an active production error)
 2. New `property_baseline_performance` table
 
+### Before starting: update the import line
+
+`jsonb` is not currently imported. Add it (and `pgEnum` is already present):
+
+```typescript
+import {
+  bigserial,
+  text,
+  timestamp,
+  pgTable,
+  real,
+  pgEnum,
+  integer,
+  boolean,
+  smallint,
+  bigint,
+  uniqueIndex,
+  jsonb,          // ← add this
+} from "drizzle-orm/pg-core";
+```
+
 ---
 
 ## 1. `epc_property` — new columns
@@ -122,12 +143,28 @@ curtainWallAge:       text("curtain_wall_age"),
 > **Note on `draughtProofed` and `permanentShuttersPresent`:** these are `boolean` in the
 > current TypeScript schema but `Union[bool, str]` JSONB in the Python model. Change them
 > to `jsonb(...).notNull()` — the TypeScript boolean type was incorrect.
+>
+> These two columns also require **boolean-specific** USING clauses in the generated migration
+> (PostgreSQL will not implicitly cast `boolean` to `jsonb`):
+>
+> ```sql
+> ALTER TABLE "epc_window" ALTER COLUMN "draught_proofed"
+>   SET DATA TYPE jsonb
+>   USING to_json("draught_proofed")::jsonb;
+>
+> ALTER TABLE "epc_window" ALTER COLUMN "permanent_shutters_present"
+>   SET DATA TYPE jsonb
+>   USING to_json("permanent_shutters_present")::jsonb;
+> ```
+>
+> `to_json` converts `true`/`false` to JSON booleans (not quoted strings), which is correct
+> for the `Union[bool, str]` Python type.
 
 ---
 
 ## 6. New table: `epc_renewable_heat_incentive`
 
-Add this table to `src/app/schema/property.ts`:
+Add this table to `src/app/db/schema/property.ts`:
 
 ```typescript
 export const epcRenewableHeatIncentive = pgTable(
@@ -151,7 +188,18 @@ export const epcRenewableHeatIncentive = pgTable(
 
 ## 7. New table: `property_baseline_performance`
 
-Add this table to `src/app/schema/property.ts`:
+First, add the enum (before the table definition):
+
+```typescript
+export const rebaselineReasonEnum = pgEnum("rebaseline_reason", [
+  "none",
+  "pre_sap10",
+  "physical_state_changed",
+  "both",
+]);
+```
+
+Then add the table to `src/app/db/schema/property.ts`:
 
 ```typescript
 export const propertyBaselinePerformance = pgTable(
@@ -165,7 +213,7 @@ export const propertyBaselinePerformance = pgTable(
 
     // Lodged performance (from gov EPC register)
     lodgedSapScore: integer("lodged_sap_score").notNull(),
-    lodgedEpcBand: text("lodged_epc_band").notNull(),
+    lodgedEpcBand: epcEnum("lodged_epc_band").notNull(),
     lodgedCo2EmissionsTPerYr: real("lodged_co2_emissions_t_per_yr").notNull(),
     lodgedPrimaryEnergyIntensityKwhPerM2Yr: integer(
       "lodged_primary_energy_intensity_kwh_per_m2_yr",
@@ -173,7 +221,7 @@ export const propertyBaselinePerformance = pgTable(
 
     // Effective performance (what modelling scored against)
     effectiveSapScore: integer("effective_sap_score").notNull(),
-    effectiveEpcBand: text("effective_epc_band").notNull(),
+    effectiveEpcBand: epcEnum("effective_epc_band").notNull(),
     effectiveCo2EmissionsTPerYr: real(
       "effective_co2_emissions_t_per_yr",
     ).notNull(),
@@ -181,7 +229,7 @@ export const propertyBaselinePerformance = pgTable(
       "effective_primary_energy_intensity_kwh_per_m2_yr",
     ).notNull(),
 
-    rebaselineReason: text("rebaseline_reason").notNull(),
+    rebaselineReason: rebaselineReasonEnum("rebaseline_reason").notNull(),
 
     // Interim energy demand (from EPC RHI data; superseded by bill block below once populated)
     spaceHeatingKwh: real("space_heating_kwh").notNull(),