diff --git a/server/src/db/json-columns.ts b/server/src/db/json-columns.ts
new file mode 100644
index 000000000..f9c0e22f6
--- /dev/null
+++ b/server/src/db/json-columns.ts
@@ -0,0 +1,90 @@
+import { z } from 'zod';
+import type { JsonColumn } from '../utils/json-column';
+
+/**
+ * The JSON-in-TEXT columns the services decode, one declaration each: the shape
+ * the column holds and what a reader gets when a row is empty or broken. Read
+ * them with `decodeJson`/`decodeJsonResult` and write server-built values with
+ * `encodeJson` (`utils/json-column.ts`), never with a bare `JSON.parse` at the
+ * call site.
+ *
+ * These are storage shapes, not API contracts: `reservations.metadata` goes out
+ * as the stored string, and the scope lists are plain string arrays whose
+ * values the OAuth layer checks against its own scope table.
+ */
+
+/** The free-form booking details (times, carrier, legs, the mirrored price). Old rows can hold a JSON string of the JSON. */
+export const RESERVATION_METADATA: JsonColumn<Record<string, unknown>> = {
+  column: 'reservations.metadata',
+  schema: z.record(z.string(), z.unknown()),
+  fallback: () => ({}),
+  unwrapDoubleEncoded: true,
+};
+
+const stringList = z.array(z.string());
+
+/** The scopes an OAuth token was issued with. A broken row grants nothing. */
+export const OAUTH_TOKEN_SCOPES: JsonColumn<string[]> = {
+  column: 'oauth_tokens.scopes',
+  schema: stringList,
+  fallback: () => [],
+};
+
+/** The scopes an OAuth client may ask for. A broken row allows nothing. */
+export const OAUTH_CLIENT_ALLOWED_SCOPES: JsonColumn<string[]> = {
+  column: 'oauth_clients.allowed_scopes',
+  schema: stringList,
+  fallback: () => [],
+};
+
+/** The redirect URIs an OAuth client registered. A broken row matches none. */
+export const OAUTH_CLIENT_REDIRECT_URIS: JsonColumn<string[]> = {
+  column: 'oauth_clients.redirect_uris',
+  schema: stringList,
+  fallback: () => [],
+};
+
+/** The scopes a user consented to for a client. A broken row counts as consent to nothing, so the user is asked again. */
+export const OAUTH_CONSENT_SCOPES: JsonColumn<string[]> = {
+  column: 'oauth_consents.scopes',
+  schema: stringList,
+  fallback: () => [],
+};
+
+/** A limited API token's scopes; the reader keeps the strings it knows. */
+export const MCP_TOKEN_API_SCOPES: JsonColumn<unknown[]> = {
+  column: 'mcp_tokens.api_scopes',
+  schema: z.array(z.unknown()),
+  fallback: () => [],
+};
+
+/** The hashed MFA backup codes; the reader keeps the strings. A broken row holds no codes. */
+export const USER_MFA_BACKUP_CODES: JsonColumn<unknown[]> = {
+  column: 'users.mfa_backup_codes',
+  schema: z.array(z.unknown()),
+  fallback: () => [],
+};
+
+/** A journey entry's tags. */
+export const JOURNEY_ENTRY_TAGS: JsonColumn<string[]> = {
+  column: 'journey_entries.tags',
+  schema: z.array(z.string()),
+  fallback: () => [],
+};
+
+/**
+ * A journey entry's pros and cons (`{ pros, cons }`). Checked as an object
+ * only: the lists inside go out as they were stored.
+ */
+export const JOURNEY_ENTRY_PROS_CONS: JsonColumn<Record<string, unknown> | null> = {
+  column: 'journey_entries.pros_cons',
+  schema: z.record(z.string(), z.unknown()).nullable(),
+  fallback: () => null,
+};
+
+/** A poll's options: plain labels, or `{ label }` objects from older rows. Checked as a list only. */
+export const COLLAB_POLL_OPTIONS: JsonColumn<unknown[]> = {
+  column: 'collab_polls.options',
+  schema: z.array(z.unknown()),
+  fallback: () => [],
+};
diff --git a/server/src/nest/accommodations/accommodations.service.ts b/server/src/nest/accommodations/accommodations.service.ts
index 641c50cb8..f3310d553 100644
--- a/server/src/nest/accommodations/accommodations.service.ts
+++ b/server/src/nest/accommodations/accommodations.service.ts
@@ -24,6 +24,8 @@ import { BudgetItems } from '../../db/entities/BudgetItems.entity';
 import type { BudgetItemsRepository } from '../../db/repositories/BudgetItems.repository';
 import { carryViasWith, locatedStopIdsWith, reseatOwnStopWith, seatHolds, seatIndexAmong, seatIndexWith, type Night } from './night-seat';
 import type { User } from '../../types';
+import { RESERVATION_METADATA } from '../../db/json-columns';
+import { decodeJson, encodeJson } from '../../utils/json-column';
 
 type Trip = TripAccess;
 
@@ -587,7 +589,7 @@ export class AccommodationsService {
         confirmation_number: confirmation || null,
         notes: notes || null,
         accommodation_id: legacyBoundIntegerText(newId),
-        metadata: Object.keys(meta).length > 0 ? JSON.stringify(meta) : null,
+        metadata: Object.keys(meta).length > 0 ? encodeJson(RESERVATION_METADATA, meta) : null,
       });
 
       return { accommodationId: newId, mirror: await this.mirrorStay(newId, place_id ?? null, start_day_id, check_in) };
@@ -646,11 +648,11 @@ export class AccommodationsService {
       // would silently leave the others on the old times.
       const linkedRes = await this.reservationsRepo.listIdMetadataByStay(existing.id);
       for (const res of linkedRes) {
-        const meta = res.metadata ? JSON.parse(res.metadata) : {};
+        const meta = decodeJson(RESERVATION_METADATA, res.metadata, `reservation ${res.id}`);
         if (newCheckIn) meta.check_in_time = newCheckIn;
         if (newCheckInEnd) meta.check_in_end_time = newCheckInEnd;
         if (newCheckOut) meta.check_out_time = newCheckOut;
-        await this.reservationsRepo.setMetadataAndConfirmation(res.id, JSON.stringify(meta), newConfirmation || null);
+        await this.reservationsRepo.setMetadataAndConfirmation(res.id, encodeJson(RESERVATION_METADATA, meta), newConfirmation || null);
       }
       return moved;
     });
diff --git a/server/src/nest/airports/airports.service.ts b/server/src/nest/airports/airports.service.ts
index d9f4c5d7a..ab88a76f5 100644
--- a/server/src/nest/airports/airports.service.ts
+++ b/server/src/nest/airports/airports.service.ts
@@ -8,6 +8,8 @@ import { ReservationEndpoints } from '../../db/entities/ReservationEndpoints.ent
 import { ReservationEndpointsRepository } from '../../db/repositories/ReservationEndpoints.repository';
 import { CronRegistrarService } from '../scheduling/cron-registrar.service';
 import { UnitOfWork } from '../database/unit-of-work';
+import { RESERVATION_METADATA } from '../../db/json-columns';
+import { decodeJsonResult, logJsonFailure } from '../../utils/json-column';
 
 /**
  * The in-container face of the airport dataset, plus the flight-endpoint
@@ -96,8 +98,13 @@ export class AirportsService implements OnApplicationBootstrap {
   /** One flight's endpoints, or its review flag. True when it was filled. */
   private async backfillOne(r: { id: number; metadata: string | null; reservation_time: string | null; reservation_end_time: string | null }): Promise<boolean> {
     if (!r.metadata) { await this.reservationsRepo.markNeedsReview(r.id); return false; }
-    let meta: any;
-    try { meta = JSON.parse(r.metadata); } catch { await this.reservationsRepo.markNeedsReview(r.id); return false; }
+    const decoded = decodeJsonResult(RESERVATION_METADATA, r.metadata);
+    if (!decoded.ok) {
+      logJsonFailure(RESERVATION_METADATA, decoded.reason, `reservation ${r.id}`);
+      await this.reservationsRepo.markNeedsReview(r.id);
+      return false;
+    }
+    const meta = decoded.value;
 
     const dep = meta.departure_airport ? findByIata(String(meta.departure_airport).slice(0, 3)) : null;
     const arr = meta.arrival_airport ? findByIata(String(meta.arrival_airport).slice(0, 3)) : null;
diff --git a/server/src/nest/auth/auth.helpers.ts b/server/src/nest/auth/auth.helpers.ts
index f40df04b2..bdafd31fd 100644
--- a/server/src/nest/auth/auth.helpers.ts
+++ b/server/src/nest/auth/auth.helpers.ts
@@ -2,6 +2,8 @@ import bcrypt from 'bcryptjs';
 import crypto from 'crypto';
 import { User } from '../../types';
 import { utcSuffix } from '../../db/types';
+import { USER_MFA_BACKUP_CODES } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 import { decrypt_api_key } from '../common/crypto/apiKeyCrypto';
 
 /**
@@ -140,11 +142,5 @@ export function generateBackupCodes(count = MFA_BACKUP_CODE_COUNT): string[] {
 }
 
 export function parseBackupCodeHashes(raw: string | null | undefined): string[] {
-  if (!raw) return [];
-  try {
-    const parsed = JSON.parse(raw);
-    return Array.isArray(parsed) ? parsed.filter(v => typeof v === 'string') : [];
-  } catch {
-    return [];
-  }
+  return decodeJson(USER_MFA_BACKUP_CODES, raw).filter((v): v is string => typeof v === 'string');
 }
diff --git a/server/src/nest/budget/budget.service.ts b/server/src/nest/budget/budget.service.ts
index 7c36f54dc..c561279cf 100644
--- a/server/src/nest/budget/budget.service.ts
+++ b/server/src/nest/budget/budget.service.ts
@@ -26,6 +26,8 @@ import { Trips } from '../../db/entities/Trips.entity';
 import type { TripsRepository, TripAccess } from '../../db/repositories/Trips.repository';
 import { TripMembers } from '../../db/entities/TripMembers.entity';
 import type { TripMembersRepository } from '../../db/repositories/TripMembers.repository';
+import { RESERVATION_METADATA } from '../../db/json-columns';
+import { decodeJson, encodeJson } from '../../utils/json-column';
 
 type Trip = TripAccess;
 
@@ -926,19 +928,16 @@ export class BudgetService {
     await this.syncReservationPrice(String(tripId), reservationId, total, socketId, allInTripCurrency ? null : codeOf(linked[0].currency) || null);
   }
 
-  /**
-   * The counterpart to syncReservationPrice: take the mirrored total back off
-   * the booking. Non-fatal, exactly like the writer.
-   */
+  /** The counterpart to syncReservationPrice: take the mirrored total back off the booking. Non-fatal, like the writer. */
   private async clearReservationPrice(tripId: string | number, reservationId: number): Promise<void> {
     try {
       const reservation = await this.reservationsRepo.getIdAndMetadata(reservationId, tripId);
       if (!reservation?.metadata) return;
-      const meta = JSON.parse(reservation.metadata);
-      if (!meta || typeof meta !== 'object' || meta.price === undefined) return;
+      const meta = decodeJson(RESERVATION_METADATA, reservation.metadata, `reservation ${reservation.id}`);
+      if (meta.price === undefined) return;
       delete meta.price;
       delete meta.priceCurrency;
-      await this.reservationsRepo.setMetadata(reservation.id, JSON.stringify(meta));
+      await this.reservationsRepo.setMetadata(reservation.id, encodeJson(RESERVATION_METADATA, meta));
       const updatedRes = await this.reservationsRepo.getFull(reservation.id);
       this.realtime.broadcast(String(tripId), 'reservation:updated', { reservation: updatedRes }, undefined);
     } catch (err) {
@@ -1637,7 +1636,7 @@ export class BudgetService {
     try {
       const reservation = await this.reservationsRepo.getIdAndMetadata(reservationId, tripId);
       if (!reservation) return;
-      const meta = reservation.metadata ? JSON.parse(reservation.metadata) : {};
+      const meta = decodeJson(RESERVATION_METADATA, reservation.metadata, `reservation ${reservation.id}`);
       // Cent-clean, so a booking never inherits float noise from the expense
       // it is linked to — and so a row stamped before #1964 heals on the next
       // edit. The panels print this string as it stands.
@@ -1648,7 +1647,7 @@ export class BudgetService {
         if (currency) meta.priceCurrency = currency.toUpperCase();
         else delete meta.priceCurrency;
       }
-      await this.reservationsRepo.setMetadata(reservation.id, JSON.stringify(meta));
+      await this.reservationsRepo.setMetadata(reservation.id, encodeJson(RESERVATION_METADATA, meta));
       const updatedRes = await this.reservationsRepo.getFull(reservation.id);
       this.realtime.broadcast(tripId, 'reservation:updated', { reservation: updatedRes }, socketId);
     } catch (err) {
diff --git a/server/src/nest/calendar/calendar.service.ts b/server/src/nest/calendar/calendar.service.ts
index 5961d5688..471ea803a 100644
--- a/server/src/nest/calendar/calendar.service.ts
+++ b/server/src/nest/calendar/calendar.service.ts
@@ -12,6 +12,8 @@ import { DayNotes } from '../../db/entities/DayNotes.entity';
 import type { DayNotesRepository } from '../../db/repositories/DayNotes.repository';
 import { Reservations } from '../../db/entities/Reservations.entity';
 import type { ReservationsRepository } from '../../db/repositories/Reservations.repository';
+import { RESERVATION_METADATA } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 
 /** The VCALENDAR preamble every TREK calendar starts with, single-trip or merged. */
 export const CALENDAR_HEADER =
@@ -613,7 +615,7 @@ export class CalendarService {
     interface LegTimes { from: string | null; to: string | null; label: string | null; confirmation: string | null; dep: { date: string; time: string; zone: string | null }; arr: { date: string; time: string; zone: string | null } | null }
     const legsOf = (r: any): LegTimes[] | null => {
       if (r.type !== 'flight' && r.type !== 'train' && r.type !== 'cruise') return null;
-      const meta = r.metadata ? (typeof r.metadata === 'string' ? JSON.parse(r.metadata) : r.metadata) : {};
+      const meta = decodeJson(RESERVATION_METADATA, r.metadata, `reservation ${r.id}`);
       const legs = Array.isArray(meta.legs) ? meta.legs : [];
       if (legs.length < 2) return null;
       const eps = endpointsMap.get(r.id);
@@ -681,7 +683,7 @@ export class CalendarService {
     // lines: dropping the block must not drop the route or the confirmation with
     // it (#2068).
     function describeReservation(r: any): string {
-      const meta = r.metadata ? (typeof r.metadata === 'string' ? JSON.parse(r.metadata) : r.metadata) : {};
+      const meta = decodeJson(RESERVATION_METADATA, r.metadata, `reservation ${r.id}`);
       let desc = r.type ? `Type: ${r.type}` : '';
       if (r.confirmation_number) desc += `\nConfirmation: ${r.confirmation_number}`;
       if (meta.airline) desc += `\nAirline: ${meta.airline}`;
diff --git a/server/src/nest/collab/collab.service.ts b/server/src/nest/collab/collab.service.ts
index e27c88931..3095cec28 100644
--- a/server/src/nest/collab/collab.service.ts
+++ b/server/src/nest/collab/collab.service.ts
@@ -28,6 +28,8 @@ import { CollabMessages } from '../../db/entities/CollabMessages.entity';
 import type { CollabMessagesRepository, CollabMessageJoinRow } from '../../db/repositories/CollabMessages.repository';
 import { Trips } from '../../db/entities/Trips.entity';
 import type { TripsRepository } from '../../db/repositories/Trips.repository';
+import { COLLAB_POLL_OPTIONS } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 
 type Trip = TripAccess;
 
@@ -366,7 +368,7 @@ export class CollabService {
     const poll = await this.pollsRepo.findWithUser(pollId);
     if (!poll) return null;
 
-    const options: (string | { label: string })[] = JSON.parse(poll.options);
+    const options = decodeJson(COLLAB_POLL_OPTIONS, poll.options, `poll ${poll.id}`) as (string | { label: string })[];
 
     const votes = await this.pollVotesRepo.listForPoll(poll.id);
 
@@ -419,7 +421,7 @@ export class CollabService {
     if (!poll) return { error: 'not_found' };
     if (poll.closed) return { error: 'closed' };
 
-    const options = JSON.parse(poll.options);
+    const options = decodeJson(COLLAB_POLL_OPTIONS, poll.options, `poll ${poll.id}`);
     if (!Number.isInteger(optionIndex) || optionIndex < 0 || optionIndex >= options.length) {
       return { error: 'invalid_index' };
     }
diff --git a/server/src/nest/integrations/airtrail-import.service.ts b/server/src/nest/integrations/airtrail-import.service.ts
index 01d69891b..23833402c 100644
--- a/server/src/nest/integrations/airtrail-import.service.ts
+++ b/server/src/nest/integrations/airtrail-import.service.ts
@@ -14,6 +14,8 @@ import { AirtrailRequestError, type AirtrailFlightRaw } from './airtrail.client'
 import { AirtrailClient } from './airtrail.client';
 import { AirtrailService } from './airtrail.service';
 import { canonicalHash, mapFlightToReservation, mapFlightsToMultiLegReservation, normalizeFlight } from './airtrail.mapper';
+import { RESERVATION_METADATA } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 
 interface ExistingFlightRow {
   id: number;
@@ -165,12 +167,8 @@ export class AirtrailImportService {
     const linkedRows = await this.reservationsRepo.listAirtrailLinkedForTrip(tripIdNum);
     for (const row of linkedRows) {
       if (row.external_id) linkedIds.add(row.external_id);
-      try {
-        const ids = row.metadata ? JSON.parse(row.metadata).airtrail_ids : null;
-        if (Array.isArray(ids)) for (const id of ids) linkedIds.add(String(id));
-      } catch {
-        /* malformed metadata — ignore */
-      }
+      const ids = decodeJson(RESERVATION_METADATA, row.metadata, `airtrail ${row.external_id}`).airtrail_ids;
+      if (Array.isArray(ids)) for (const id of ids) linkedIds.add(String(id));
     }
 
     const existing = await this.reservationsRepo.listFlightReservationsForTrip(tripIdNum);
@@ -194,12 +192,7 @@ export class AirtrailImportService {
 
     const existingSigs = new Set<string>();
     for (const row of existing) {
-      let meta: Record<string, any> = {};
-      try {
-        meta = row.metadata ? JSON.parse(row.metadata) : {};
-      } catch {
-        /* malformed metadata — ignore */
-      }
+      const meta = decodeJson(RESERVATION_METADATA, row.metadata, `reservation ${row.id}`);
       const eps = endpointsByReservation.get(row.id) ?? [];
       const legs: any[] | null = Array.isArray(meta.legs) ? meta.legs : null;
       if (legs && legs.length > 1) {
@@ -218,7 +211,7 @@ export class AirtrailImportService {
       } else {
         const from = eps[0]?.code ?? null;
         const to = eps.length > 1 ? eps[eps.length - 1].code : null;
-        const sig = softSignature(depDate(row.reservation_time), meta.flight_number ?? null, from, to);
+        const sig = softSignature(depDate(row.reservation_time), (meta.flight_number as string | null | undefined) ?? null, from, to);
         if (sig) existingSigs.add(sig);
       }
     }
diff --git a/server/src/nest/integrations/airtrail-link.service.ts b/server/src/nest/integrations/airtrail-link.service.ts
index e4a54d876..362023406 100644
--- a/server/src/nest/integrations/airtrail-link.service.ts
+++ b/server/src/nest/integrations/airtrail-link.service.ts
@@ -16,6 +16,8 @@ import { AirtrailClient } from './airtrail.client';
 import { AirtrailService } from './airtrail.service';
 import { canonicalHash } from './airtrail.mapper';
 import { buildSavePayload } from './airtrail-sync.helpers';
+import { RESERVATION_METADATA } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 
 /**
  * The AirTrail link lifecycle — the enablement gate, the detach policy, the
@@ -70,12 +72,9 @@ export class AirtrailLinkService {
    * AirTrail flight to span the whole route (#1535).
    */
   async hasLocalMultiLegShape(reservationId: number, metadataJson: string | null | undefined): Promise<boolean> {
-    try {
-      const meta = metadataJson ? JSON.parse(metadataJson) : {};
-      if (Array.isArray(meta?.legs) && meta.legs.length > 1) return true;
-    } catch {
-      /* malformed metadata — fall through to the endpoint count */
-    }
+    // Malformed metadata falls through to the endpoint count.
+    const legs = decodeJson(RESERVATION_METADATA, metadataJson, `reservation ${reservationId}`).legs;
+    if (Array.isArray(legs) && legs.length > 1) return true;
     const n = await this.endpointsRepo.count({ reservation: reservationId });
     return n > 2;
   }
diff --git a/server/src/nest/integrations/airtrail-sync.helpers.ts b/server/src/nest/integrations/airtrail-sync.helpers.ts
index a174cbf79..370d0b5c8 100644
--- a/server/src/nest/integrations/airtrail-sync.helpers.ts
+++ b/server/src/nest/integrations/airtrail-sync.helpers.ts
@@ -1,6 +1,8 @@
 import { entityCode } from './airtrail.mapper';
 import { flightPassengers, ownPassenger } from './airtrail.client';
 import type { AirtrailFlightRaw, AirtrailPassengerWrite, AirtrailSavePayload } from './airtrail.client';
+import { RESERVATION_METADATA } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 
 /**
  * The pure half of the AirTrail push: turning a TREK reservation plus the flight
@@ -27,12 +29,7 @@ function splitLocal(dt: string | null | undefined): { date: string | null; time:
  * (#1240).
  */
 export function buildSavePayload(reservation: any, existing: AirtrailFlightRaw): AirtrailSavePayload | null {
-  let meta: Record<string, any>;
-  try {
-    meta = reservation.metadata ? JSON.parse(reservation.metadata) : {};
-  } catch {
-    meta = {};
-  }
+  const meta = decodeJson(RESERVATION_METADATA, reservation.metadata, `reservation ${reservation.id}`);
   const endpoints: any[] = reservation.endpoints || [];
   const fromEp = endpoints.find((e) => e.role === 'from');
   const toEp = endpoints.find((e) => e.role === 'to');
diff --git a/server/src/nest/journey/journey-entry-row.ts b/server/src/nest/journey/journey-entry-row.ts
index 6e0116956..47eb37631 100644
--- a/server/src/nest/journey/journey-entry-row.ts
+++ b/server/src/nest/journey/journey-entry-row.ts
@@ -1,4 +1,6 @@
 import type { JourneyEntry } from '../../types';
+import { JOURNEY_ENTRY_PROS_CONS, JOURNEY_ENTRY_TAGS } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 
 /**
  * A journey entry on the way out.
@@ -39,8 +41,8 @@ export function decodeEntryRow(row: JourneyEntry): JourneyEntryWire {
   const { tags, pros_cons, stats_excluded, dismissed, is_draft, ...rest } = row;
   return {
     ...rest,
-    tags: tags ? JSON.parse(tags) : [],
-    pros_cons: pros_cons ? JSON.parse(pros_cons) : null,
+    tags: decodeJson(JOURNEY_ENTRY_TAGS, tags, `journey entry ${row.id}`),
+    pros_cons: decodeJson(JOURNEY_ENTRY_PROS_CONS, pros_cons, `journey entry ${row.id}`) as JourneyEntryWire['pros_cons'],
     stats_excluded: !!stats_excluded,
     dismissed: !!dismissed,
     is_draft: !!is_draft,
diff --git a/server/src/nest/oauth/oauth-public.controller.ts b/server/src/nest/oauth/oauth-public.controller.ts
index 5a4c6b5b3..bf3921d21 100644
--- a/server/src/nest/oauth/oauth-public.controller.ts
+++ b/server/src/nest/oauth/oauth-public.controller.ts
@@ -6,6 +6,8 @@ import { getClientIp } from '../audit/client-ip';
 import { logWarn } from '../audit/audit-log.logger';
 import { AuditService } from '../audit/audit.service';
 import { Public } from '../auth/public.decorator';
+import { OAUTH_CLIENT_ALLOWED_SCOPES } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 
 const MIN = 60_000;
 
@@ -112,7 +114,7 @@ export class OauthPublicController {
         res.status(400).json({ error: 'unauthorized_client', error_description: 'This client is not authorized for the client_credentials grant' });
         return;
       }
-      const allowedScopes: string[] = JSON.parse(client.allowed_scopes);
+      const allowedScopes = decodeJson(OAUTH_CLIENT_ALLOWED_SCOPES, client.allowed_scopes, `client ${client_id}`);
       let grantedScopes: string[];
       if (body.scope) {
         const requested = body.scope.split(' ').filter(Boolean);
diff --git a/server/src/nest/oauth/oauth-sdk.provider.ts b/server/src/nest/oauth/oauth-sdk.provider.ts
index 0475c35c4..7358d07e5 100644
--- a/server/src/nest/oauth/oauth-sdk.provider.ts
+++ b/server/src/nest/oauth/oauth-sdk.provider.ts
@@ -10,6 +10,8 @@ import { classifyRedirectUri } from './oauth.helpers';
 import { AuditService } from '../audit/audit.service';
 import { ALL_SCOPES, DEFAULT_CLIENT_SCOPES } from '../../mcp/scopes';
 import { getMcpSafeUrl } from '../../app-config';
+import { OAUTH_CLIENT_ALLOWED_SCOPES, OAUTH_CLIENT_REDIRECT_URIS } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 
 /**
  * TREK's adapters behind the MCP SDK's OAuth server interfaces, wrapping the
@@ -48,8 +50,8 @@ function rowToInfo(row: NonNullable<Awaited<ReturnType<OauthService['getSdkClien
     return {
         client_id: row.client_id,
         client_name: row.name,
-        redirect_uris: JSON.parse(row.redirect_uris) as string[],
-        scope: (JSON.parse(row.allowed_scopes) as string[]).join(' '),
+        redirect_uris: decodeJson(OAUTH_CLIENT_REDIRECT_URIS, row.redirect_uris, `client ${row.client_id}`),
+        scope: decodeJson(OAUTH_CLIENT_ALLOWED_SCOPES, row.allowed_scopes, `client ${row.client_id}`).join(' '),
         token_endpoint_auth_method: row.is_public ? 'none' : 'client_secret_post',
         grant_types: ['authorization_code', 'refresh_token'],
         response_types: ['code'],
diff --git a/server/src/nest/oauth/oauth.service.ts b/server/src/nest/oauth/oauth.service.ts
index 4a4097775..56dcf1411 100644
--- a/server/src/nest/oauth/oauth.service.ts
+++ b/server/src/nest/oauth/oauth.service.ts
@@ -36,6 +36,13 @@ import {
   timingSafeEqualHex,
 } from './oauth.helpers';
 import { dbNow, parseDbTimestamp } from '../../db/types';
+import {
+  OAUTH_CLIENT_ALLOWED_SCOPES,
+  OAUTH_CLIENT_REDIRECT_URIS,
+  OAUTH_CONSENT_SCOPES,
+  OAUTH_TOKEN_SCOPES,
+} from '../../db/json-columns';
+import { decodeJson, decodeJsonResult, encodeJson, logJsonFailure } from '../../utils/json-column';
 import { AUTH_CODE_TTL_MS, PendingCodeStore, pendingCodesSlot, type PendingCode } from './oauth.pending-codes';
 
 export type { PendingCode } from './oauth.pending-codes';
@@ -129,8 +136,8 @@ export class OauthService {
       ...r,
       is_public: Boolean(r.is_public),
       allows_client_credentials: Boolean(r.allows_client_credentials),
-      redirect_uris: JSON.parse(r.redirect_uris),
-      allowed_scopes: JSON.parse(r.allowed_scopes),
+      redirect_uris: decodeJson(OAUTH_CLIENT_REDIRECT_URIS, r.redirect_uris, `client ${r.client_id}`),
+      allowed_scopes: decodeJson(OAUTH_CLIENT_ALLOWED_SCOPES, r.allowed_scopes, `client ${r.client_id}`),
     }));
   }
 
@@ -187,8 +194,8 @@ export class OauthService {
       name: name.trim(),
       client_id: clientId,
       client_secret_hash: secretHash,
-      redirect_uris: JSON.stringify(redirectUris),
-      allowed_scopes: JSON.stringify(allowedScopes),
+      redirect_uris: encodeJson(OAUTH_CLIENT_REDIRECT_URIS, redirectUris),
+      allowed_scopes: encodeJson(OAUTH_CLIENT_ALLOWED_SCOPES, allowedScopes),
       is_public: isPublic ? 1 : 0,
       created_via: createdVia,
       allows_client_credentials: isMachineClient ? 1 : 0,
@@ -202,8 +209,8 @@ export class OauthService {
         user_id: row.user_id,
         name: row.name,
         client_id: row.client_id,
-        redirect_uris: JSON.parse(row.redirect_uris),
-        allowed_scopes: JSON.parse(row.allowed_scopes),
+        redirect_uris: decodeJson(OAUTH_CLIENT_REDIRECT_URIS, row.redirect_uris, `client ${row.client_id}`),
+        allowed_scopes: decodeJson(OAUTH_CLIENT_ALLOWED_SCOPES, row.allowed_scopes, `client ${row.client_id}`),
         created_at: row.created_at,
         is_public: Boolean(row.is_public),
         allows_client_credentials: Boolean(row.allows_client_credentials),
@@ -281,14 +288,14 @@ export class OauthService {
 
   async getConsent(clientId: string, userId: number): Promise<string[] | null> {
     const row = await this.consents.findScopes(clientId, userId);
-    return row ? JSON.parse(row.scopes) : null;
+    return row ? decodeJson(OAUTH_CONSENT_SCOPES, row.scopes, `client ${clientId} user ${userId}`) : null;
   }
 
   async saveConsent(clientId: string, userId: number, scopes: string[], ip?: string | null): Promise<void> {
     // Union existing consent with newly approved scopes (M5: never narrow stored consent)
     const existing = (await this.getConsent(clientId, userId)) ?? [];
     const merged = Array.from(new Set([...existing, ...scopes]));
-    await this.consents.upsertGrant(clientId, userId, JSON.stringify(merged));
+    await this.consents.upsertGrant(clientId, userId, encodeJson(OAUTH_CONSENT_SCOPES, merged));
     await this.audit.writeAudit({ userId, action: 'oauth.consent.grant', details: { client_id: clientId, scopes: merged }, ip });
   }
 
@@ -327,7 +334,7 @@ export class OauthService {
       user_id: userId,
       access_token_hash: accessHash,
       refresh_token_hash: refreshHash,
-      scopes: JSON.stringify(scopes),
+      scopes: encodeJson(OAUTH_TOKEN_SCOPES, scopes),
       audience,
       access_token_expires_at: dbNow(accessExpiry),
       refresh_token_expires_at: dbNow(refreshExpiry),
@@ -373,7 +380,7 @@ export class OauthService {
       user_id: userId,
       access_token_hash: accessHash,
       refresh_token_hash: placeholderHash,
-      scopes: JSON.stringify(scopes),
+      scopes: encodeJson(OAUTH_TOKEN_SCOPES, scopes),
       audience,
       access_token_expires_at: dbNow(accessExpiry),
       refresh_token_expires_at: dbNow(now),
@@ -415,7 +422,7 @@ export class OauthService {
 
     return {
       user: { id: row.user_id, username: row.username, email: row.email, role: row.role as 'admin' | 'user' },
-      scopes: JSON.parse(row.scopes),
+      scopes: decodeJson(OAUTH_TOKEN_SCOPES, row.scopes, `client ${row.client_id} user ${row.user_id}`),
       clientId: row.client_id,
       audience: row.audience ?? null,
     };
@@ -489,7 +496,7 @@ export class OauthService {
       // to take the whole chain down with it. Issue a sibling pair off the same
       // parent so each client walks away with its own token.
       if (await this.isConcurrentRotation(row)) {
-        const tokens = await this.issueTokens(clientId, row.user_id, JSON.parse(row.scopes), row.id, row.audience ?? null);
+        const tokens = await this.issueTokens(clientId, row.user_id, decodeJson(OAUTH_TOKEN_SCOPES, row.scopes, `token ${row.id}`), row.id, row.audience ?? null);
         await this.audit.writeAudit({
           userId: row.user_id,
           action: 'oauth.token.refresh',
@@ -529,7 +536,7 @@ export class OauthService {
     // to leave the old token revoked with no successor, logging the client out.
     const tokens = await this.uow.transactional(async () => {
       await this.tokens.revokeById(row.id);
-      return await this.issueTokens(clientId, row.user_id, JSON.parse(row.scopes), row.id, row.audience ?? null);
+      return await this.issueTokens(clientId, row.user_id, decodeJson(OAUTH_TOKEN_SCOPES, row.scopes, `token ${row.id}`), row.id, row.audience ?? null);
     });
     await this.audit.writeAudit({ userId: row.user_id, action: 'oauth.token.refresh', details: { client_id: clientId }, ip });
 
@@ -565,7 +572,7 @@ export class OauthService {
 
   async listOAuthSessions(userId: number): Promise<Record<string, unknown>[]> {
     const rows = await this.tokens.listActiveByUser(userId);
-    return rows.map(r => ({ ...r, ...expiriesAsIso(r), scopes: JSON.parse(r.scopes) }));
+    return rows.map(r => ({ ...r, ...expiriesAsIso(r), scopes: decodeJson(OAUTH_TOKEN_SCOPES, r.scopes, `token ${r.id}`) }));
   }
 
   async revokeSession(
@@ -628,7 +635,7 @@ export class OauthService {
       return { valid: false, error: 'invalid_client', error_description: 'Unknown client_id' };
     }
 
-    const allowedUris: string[] = JSON.parse(client.redirect_uris);
+    const allowedUris = decodeJson(OAUTH_CLIENT_REDIRECT_URIS, client.redirect_uris, `client ${client.client_id}`);
     // Exact match except for the loopback port, which RFC 8252 §7.3 leaves to
     // the OS, and which the SDK's authorize handler already relaxes, so a
     // native client got a 302 to consent and an invalid_redirect_uri from this
@@ -658,7 +665,7 @@ export class OauthService {
       return { valid: false, error: 'invalid_scope', error_description: 'At least one scope is required' };
     }
 
-    const allowedScopes: string[] = JSON.parse(client.allowed_scopes);
+    const allowedScopes = decodeJson(OAUTH_CLIENT_ALLOWED_SCOPES, client.allowed_scopes, `client ${client.client_id}`);
     // Narrow to the intersection: drop scopes the client isn't permitted for rather
     // than rejecting the whole request (per OAuth 2.0 §3.3 scope narrowing).
     const grantedScopes = requestedScopes.filter(s => allowedScopes.includes(s));
@@ -728,12 +735,10 @@ export class OauthService {
     const rows = await this.tokens.listAllActiveWithClientAndUser();
     // One malformed row must not 500 the whole admin OAuth-sessions panel.
     return rows.map((r) => {
-      let scopes: unknown;
-      try {
-        scopes = JSON.parse(r.scopes);
-      } catch {
-        scopes = null;
-      }
+      // The admin panel has always shown null for a row it cannot read.
+      const decoded = decodeJsonResult(OAUTH_TOKEN_SCOPES, r.scopes);
+      if (!decoded.ok && decoded.reason !== 'empty') logJsonFailure(OAUTH_TOKEN_SCOPES, decoded.reason, `token ${r.id}`);
+      const scopes = decoded.ok ? decoded.value : null;
       return { ...r, ...expiriesAsIso(r), scopes };
     });
   }
diff --git a/server/src/nest/reservations/reservation-metadata.ts b/server/src/nest/reservations/reservation-metadata.ts
index bcfc3cfd0..b3985ba32 100644
--- a/server/src/nest/reservations/reservation-metadata.ts
+++ b/server/src/nest/reservations/reservation-metadata.ts
@@ -1,3 +1,6 @@
+import { RESERVATION_METADATA } from '../../db/json-columns';
+import { decodeJsonResult, logJsonFailure } from '../../utils/json-column';
+
 /**
  * Metadata keys on a reservation that the booking forms do not own.
  *
@@ -14,15 +17,10 @@
 
 /** Read a stored metadata column into an object, or null if it is not one. */
 function parseStored(stored: string | null | undefined): Record<string, unknown> | null {
-  if (!stored) return null;
-  try {
-    const parsed: unknown = JSON.parse(stored);
-    return parsed && typeof parsed === 'object' && !Array.isArray(parsed)
-      ? (parsed as Record<string, unknown>)
-      : null;
-  } catch {
-    return null;
-  }
+  const decoded = decodeJsonResult(RESERVATION_METADATA, stored);
+  if (decoded.ok) return decoded.value;
+  if (decoded.reason !== 'empty') logJsonFailure(RESERVATION_METADATA, decoded.reason);
+  return null;
 }
 
 /**
diff --git a/server/src/nest/reservations/reservations.mcp.ts b/server/src/nest/reservations/reservations.mcp.ts
index e71120a87..8e69e447b 100644
--- a/server/src/nest/reservations/reservations.mcp.ts
+++ b/server/src/nest/reservations/reservations.mcp.ts
@@ -15,6 +15,8 @@ import { findByIata } from '../airports/airports.data';
 import type { EndpointInput } from './reservations.service';
 import { AssignmentsService } from '../assignments/assignments.service';
 import { transportLegInputSchema, reservationUrlSchema, type TransportLegInput } from '@trek/shared';
+import { RESERVATION_METADATA } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 
 // What counts as a transport booking, for the update_transport gate. Every value
 // ReservationsPanel renders with a transport icon, so a stored `transit` row is
@@ -138,14 +140,7 @@ type MetaRecord = Record<string, unknown>;
  * still has to accept a legs update.
  */
 function parseStoredMetadata(raw: unknown): MetaRecord {
-  if (typeof raw !== 'string' || !raw) return {};
-  try {
-    let parsed: unknown = JSON.parse(raw);
-    if (typeof parsed === 'string') parsed = JSON.parse(parsed);
-    return typeof parsed === 'object' && parsed !== null ? parsed as MetaRecord : {};
-  } catch {
-    return {};
-  }
+  return typeof raw === 'string' ? decodeJson(RESERVATION_METADATA, raw) : {};
 }
 
 interface LegPlan {
diff --git a/server/src/nest/reservations/reservations.service.ts b/server/src/nest/reservations/reservations.service.ts
index 260bd52c9..50a9a6fec 100644
--- a/server/src/nest/reservations/reservations.service.ts
+++ b/server/src/nest/reservations/reservations.service.ts
@@ -1,6 +1,6 @@
 import { BadRequestException, Injectable } from '@nestjs/common';
 import { InjectRepository } from '@mikro-orm/nestjs';
-import type { TripAccess } from '../../db/repositories/Trips.repository';
+import type { TripAccess, TripsRepository } from '../../db/repositories/Trips.repository';
 import { UnitOfWork } from '../database/unit-of-work';
 import type { TrekWsPayload, TrekWsTripEventName } from '@trek/shared';
 import { RealtimeService } from '../realtime/realtime.service';
@@ -36,8 +36,9 @@ import type { UsersRepository } from '../../db/repositories/Users.repository';
 import { Trips } from '../../db/entities/Trips.entity';
 import { BudgetItems } from '../../db/entities/BudgetItems.entity';
 import type { BudgetItemsRepository } from '../../db/repositories/BudgetItems.repository';
-import type { TripsRepository } from '../../db/repositories/Trips.repository';
 import { appClock } from '../common/timezoneService';
+import { RESERVATION_METADATA } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 
 type Trip = TripAccess;
 type BudgetEntry = { total_price?: number; category?: string; currency?: string | null; exchange_rate?: number } | undefined;
@@ -787,7 +788,7 @@ export class ReservationsService {
     // whose accommodation was just auto-created above never received its
     // metadata check-in/out times or confirmation.
     if (resolvedAccommodationId && metadata) {
-      const meta = (typeof metadata === 'string' ? JSON.parse(metadata) : metadata) as AccommodationTimesMeta;
+      const meta = decodeJson(RESERVATION_METADATA, metadata) as AccommodationTimesMeta;
       if (meta.check_in_time || meta.check_in_end_time || meta.check_out_time) {
         await this.dayAccommodationsRepo.patchTimes(
           resolvedAccommodationId, meta.check_in_time || null, meta.check_in_end_time || null, meta.check_out_time || null,
@@ -1036,9 +1037,9 @@ export class ReservationsService {
     }
 
     // Sync check-in/out to accommodation if linked
-    const resolvedMeta = nextMetadata !== undefined ? nextMetadata : (current.metadata ? JSON.parse(current.metadata as string) : null);
+    const resolvedMeta = nextMetadata !== undefined ? nextMetadata : (current.metadata ? decodeJson(RESERVATION_METADATA, current.metadata, `reservation ${idNum}`) : null);
     if (resolvedAccId && resolvedMeta) {
-      const meta = (typeof resolvedMeta === 'string' ? JSON.parse(resolvedMeta) : resolvedMeta) as AccommodationTimesMeta;
+      const meta = decodeJson(RESERVATION_METADATA, resolvedMeta) as AccommodationTimesMeta;
       const resolvedAccIdNum = accIdForRead(resolvedAccId)!;
       if (meta.check_in_time || meta.check_in_end_time || meta.check_out_time) {
         await this.dayAccommodationsRepo.patchTimes(
diff --git a/server/src/nest/tokens/token.service.ts b/server/src/nest/tokens/token.service.ts
index 70a1addec..c63217a50 100644
--- a/server/src/nest/tokens/token.service.ts
+++ b/server/src/nest/tokens/token.service.ts
@@ -17,6 +17,8 @@ import { toRowId } from '../common/row-id';
 // every consumer of this module — a nest→mcp→nest module cycle.
 import { revokeUserSessions } from '../../mcp/sessionManager';
 import { User } from '../../types';
+import { MCP_TOKEN_API_SCOPES } from '../../db/json-columns';
+import { decodeJson } from '../../utils/json-column';
 
 /**
  * What a token is allowed to drive. Stored on the row so each surface can accept
@@ -321,13 +323,7 @@ function sanitizeScopes(scopes: readonly string[] | undefined): PublicApiScope[]
  */
 function resolveGrant(mode: string | null, raw: string | null): PublicApiGrant {
   if (mode !== 'limited') return { mode: 'all', scopes: [...PUBLIC_API_SCOPES] };
-  let parsed: unknown;
-  try {
-    parsed = raw ? JSON.parse(raw) : null;
-  } catch {
-    parsed = null;
-  }
-  if (!Array.isArray(parsed)) return { mode: 'limited', scopes: [] };
+  const parsed = decodeJson(MCP_TOKEN_API_SCOPES, raw);
   const kept = sanitizeScopes(parsed.filter((value): value is string => typeof value === 'string'));
   return { mode: 'limited', scopes: kept ?? [] };
 }
diff --git a/server/src/utils/json-column.ts b/server/src/utils/json-column.ts
new file mode 100644
index 000000000..d3d36d069
--- /dev/null
+++ b/server/src/utils/json-column.ts
@@ -0,0 +1,74 @@
+import type { ZodType } from 'zod';
+import { logWarn } from '../nest/audit/audit-log.logger';
+
+/**
+ * One JSON-in-TEXT column: where it lives, the shape it holds, and what a reader
+ * gets when the stored text is missing or broken.
+ *
+ * The storage model keeps JSON in TEXT (see server/CLAUDE.md, "SQL dialect"), and
+ * the service boundary turns it into a value. Declaring the column once keeps
+ * every reader of it on the same answer: one schema, one fallback, one log line
+ * when a row does not hold what it should, instead of a `JSON.parse` per call
+ * site that throws in one place and shrugs in the next.
+ */
+export interface JsonColumn<T> {
+  /** `table.column`, for the log line. */
+  readonly column: string;
+  readonly schema: ZodType<T>;
+  /** What a reader gets for an empty column or a value that does not decode. A function, so a mutable default is fresh per call. */
+  readonly fallback: () => T;
+  /**
+   * The stored text may be a JSON string of the JSON (an old double-encoding
+   * bug). When set, one level of that is unwrapped before the schema check.
+   */
+  readonly unwrapDoubleEncoded?: boolean;
+}
+
+export type JsonDecodeFailure = 'empty' | 'invalid-json' | 'schema';
+
+export type JsonDecodeResult<T> =
+  | { ok: true; value: T; reason?: never }
+  | { ok: false; value?: never; reason: JsonDecodeFailure };
+
+/**
+ * Decode a stored value without a fallback, for the readers that react to a
+ * broken row themselves (flag it for review, skip it). A value a driver already
+ * handed back parsed (an object rather than text) is checked as it is.
+ */
+export function decodeJsonResult<T>(col: JsonColumn<T>, raw: unknown): JsonDecodeResult<T> {
+  if (raw === null || raw === undefined || raw === '') return { ok: false, reason: 'empty' };
+  let value: unknown = raw;
+  if (typeof raw === 'string') {
+    try {
+      value = JSON.parse(raw);
+      if (col.unwrapDoubleEncoded && typeof value === 'string') value = JSON.parse(value);
+    } catch {
+      return { ok: false, reason: 'invalid-json' };
+    }
+  }
+  const parsed = col.schema.safeParse(value);
+  return parsed.success ? { ok: true, value: parsed.data } : { ok: false, reason: 'schema' };
+}
+
+/**
+ * Decode a stored value, falling back to the column's default. An empty column
+ * is ordinary and falls back quietly; text that is not JSON, or JSON of the
+ * wrong shape, falls back too and is logged with `context` (a row id, say), so
+ * broken data shows up in trek.log instead of disappearing.
+ */
+export function decodeJson<T>(col: JsonColumn<T>, raw: unknown, context?: string): T {
+  const result = decodeJsonResult(col, raw);
+  if (result.ok) return result.value;
+  if (result.reason !== 'empty') logJsonFailure(col, result.reason, context);
+  return col.fallback();
+}
+
+/** Log a row whose JSON did not decode; for callers of {@link decodeJsonResult} that handle the failure themselves. */
+export function logJsonFailure(col: JsonColumn<unknown>, reason: JsonDecodeFailure, context?: string): void {
+  logWarn(`[json] ${col.column}${context ? ` (${context})` : ''}: stored value ${reason === 'schema' ? 'has the wrong shape' : 'is not valid JSON'}, using the fallback`);
+}
+
+/** The text to store for a value, checked against the column's shape first (a mismatch throws: it is a bug in the writer). */
+export function encodeJson<T>(col: JsonColumn<T>, value: T): string {
+  return JSON.stringify(col.schema.parse(value));
+}
diff --git a/server/tests/unit/nest/accommodations.service.test.ts b/server/tests/unit/nest/accommodations.service.test.ts
index 29dbfbf44..72fa943d7 100644
--- a/server/tests/unit/nest/accommodations.service.test.ts
+++ b/server/tests/unit/nest/accommodations.service.test.ts
@@ -227,6 +227,23 @@ describe('updateAccommodation', () => {
     spy.mockRestore();
   });
 
+  it('DAY-SVC-023b — a linked booking with unreadable metadata no longer fails the update; it gets the new times', async () => {
+    const { user } = createUser(testDb);
+    const trip = createTrip(testDb, user.id);
+    const day = createDay(testDb, trip.id) as { id: number };
+    const place = createPlace(testDb, trip.id, { name: 'Hotel' }) as { id: number };
+    const { accommodation: accom } = (await svc.createAccommodation(trip.id, {
+      place_id: place.id, start_day_id: day.id, end_day_id: day.id,
+    })) as { accommodation: { id: number } };
+    const before = await linkedReservation(accom.id);
+    await updateRows(await orm(), Reservations, { id: before.id }, { metadata: '{not json' });
+
+    const existing = (await svc.getAccommodation(accom.id, trip.id))!;
+    await svc.updateAccommodation(accom.id, existing as Parameters<typeof svc.updateAccommodation>[1], { check_in: '16:00' });
+
+    expect(JSON.parse((await linkedReservation(accom.id)).metadata)).toEqual({ check_in_time: '16:00' });
+  });
+
   it('DAY-SVC-023 — updates check-in and check-out times', async () => {
     const { user } = createUser(testDb);
     const trip = createTrip(testDb, user.id);
diff --git a/server/tests/unit/nest/budget.service.db.test.ts b/server/tests/unit/nest/budget.service.db.test.ts
index 501285e93..61d11e682 100644
--- a/server/tests/unit/nest/budget.service.db.test.ts
+++ b/server/tests/unit/nest/budget.service.db.test.ts
@@ -974,6 +974,17 @@ describe('linking existing expenses to bookings and places (#2084)', () => {
     expect(await metadataOf(reservationId)).toEqual({ seat: '12A', price: '30.3', priceCurrency: 'USD' });
   });
 
+  it('BUDGET-SVC-DB-072b: a booking whose metadata is not JSON gets the mirrored price instead of a logged failure', async () => {
+    const { trip, reservationId } = await tripWithBooking();
+    await updateRows(await orm(), Reservations, { id: reservationId }, { metadata: '{not json' });
+    const item = await budget.createBudgetItem(trip.id, { name: 'Fare', total_price: 42, currency: 'usd' });
+    await linkItems(reservationId, [item.id]);
+
+    await budget.resyncReservationPrice(trip.id, reservationId);
+
+    expect(await metadataOf(reservationId)).toEqual({ price: '42', priceCurrency: 'USD' });
+  });
+
   it('BUDGET-SVC-DB-052: an expense without a currency and one in the trip currency by code add up', async () => {
     // No currency means the trip's; the two rows are in the same money and the
     // booking shows their sum, not the first one alone.
diff --git a/server/tests/unit/nest/calendar.service.test.ts b/server/tests/unit/nest/calendar.service.test.ts
index 66ba56400..4c8194d89 100644
--- a/server/tests/unit/nest/calendar.service.test.ts
+++ b/server/tests/unit/nest/calendar.service.test.ts
@@ -523,6 +523,18 @@ describe('exportICS', () => {
     expect(ics).not.toContain('DESCRIPTION');
   });
 
+  it('CAL-017b: a booking whose metadata is not JSON still exports, without the metadata lines', async () => {
+    const { user } = createUser(testDb);
+    const trip = createTrip(testDb, user.id, { title: 'Broken' });
+    const reservation = createReservation(testDb, trip.id, { title: 'Garbled Flight', type: 'flight' });
+    await updateRows(orm, Reservations, { id: reservation.id }, { reservation_time: '2025-06-02T09:00', metadata: '{not json' });
+
+    const { ics } = await svc.exportICS(trip.id);
+
+    expect(ics).toContain('SUMMARY:Garbled Flight');
+    expect(ics).toContain('DESCRIPTION:Type: flight\r\n');
+  });
+
   it('CAL-018: flight metadata with only one airport emits only that side of the route', async () => {
     const { user } = createUser(testDb);
     const trip = createTrip(testDb, user.id, { title: 'Half Routes' });
diff --git a/server/tests/unit/nest/collab.service.test.ts b/server/tests/unit/nest/collab.service.test.ts
index f6faed5ec..b0e9f09a5 100644
--- a/server/tests/unit/nest/collab.service.test.ts
+++ b/server/tests/unit/nest/collab.service.test.ts
@@ -78,6 +78,7 @@ import { RateLimitService } from '../../../src/nest/common/rate-limit.service';
 import { createTestUnitOfWork, createTestAppSettingsRepo, createTestTripsRepo, sharedTestOrm } from '../../helpers/test-uow';
 import type { TestOrm } from '../../helpers/test-orm';
 import { countRows, findRow, findRows, insertRow, updateRows } from '../../helpers/factories/rows';
+import { CollabPolls } from '../../../src/db/entities/CollabPolls.entity';
 import { dbNow } from '../../../src/db/types/db-timestamp.type';
 import { CollabMessageReactions } from '../../../src/db/entities/CollabMessageReactions.entity';
 import { CollabMessages } from '../../../src/db/entities/CollabMessages.entity';
@@ -221,6 +222,16 @@ describe('votePoll', () => {
     expect(result.error).toBe('invalid_index');
   });
 
+  it('COLLAB-SVC-006b: a poll whose stored options are not JSON lists with no options and refuses every vote', async () => {
+    const { user1, trip } = setup();
+    const poll = await svc.createPoll(trip.id, user1.id, { question: 'Q?', options: ['A', 'B'] });
+    await updateRows(orm, CollabPolls, { id: poll!.id }, { options: '{broken' });
+
+    const [listed] = (await svc.listPolls(trip.id)) as Array<{ options: unknown[] }>;
+    expect(listed.options).toEqual([]);
+    expect((await svc.votePoll(trip.id, poll!.id, user1.id, 0)).error).toBe('invalid_index');
+  });
+
   it('COLLAB-SVC-007: returns error "not_found" for nonexistent poll', async () => {
     const { user1, trip } = setup();
     const result = await svc.votePoll(trip.id, 9999, user1.id, 0);
diff --git a/server/tests/unit/nest/journey-entry-row.test.ts b/server/tests/unit/nest/journey-entry-row.test.ts
new file mode 100644
index 000000000..712f0a63b
--- /dev/null
+++ b/server/tests/unit/nest/journey-entry-row.test.ts
@@ -0,0 +1,49 @@
+import { describe, expect, it, vi } from 'vitest';
+
+const logMock = vi.hoisted(() => ({ logInfo: vi.fn(), logError: vi.fn(), logWarn: vi.fn(), logDebug: vi.fn() }));
+vi.mock('../../../src/nest/audit/audit-log.logger', () => logMock);
+
+import { decodeEntryRow } from '../../../src/nest/journey/journey-entry-row';
+import type { JourneyEntry } from '../../../src/types';
+
+const row = (over: Partial<JourneyEntry> = {}): JourneyEntry =>
+  ({
+    id: 5,
+    journey_id: 1,
+    author_id: 1,
+    type: 'entry',
+    entry_date: '2026-01-01',
+    visibility: 'private',
+    sort_order: 0,
+    tags: null,
+    pros_cons: null,
+    stats_excluded: 0,
+    dismissed: 0,
+    is_draft: 1,
+    ...over,
+  }) as JourneyEntry;
+
+describe('decodeEntryRow', () => {
+  it('JENTRYROW-001: decodes the JSON columns and turns the flags into booleans', () => {
+    const wire = decodeEntryRow(row({ tags: '["beach","food"]', pros_cons: '{"pros":["sun"],"cons":["crowds"]}' }));
+    expect(wire.tags).toEqual(['beach', 'food']);
+    expect(wire.pros_cons).toEqual({ pros: ['sun'], cons: ['crowds'] });
+    expect(wire.stats_excluded).toBe(false);
+    expect(wire.dismissed).toBe(false);
+    expect(wire.is_draft).toBe(true);
+  });
+
+  it('JENTRYROW-002: empty columns are an empty tag list and no pros/cons', () => {
+    const wire = decodeEntryRow(row());
+    expect(wire.tags).toEqual([]);
+    expect(wire.pros_cons).toBeNull();
+    expect(logMock.logWarn).not.toHaveBeenCalled();
+  });
+
+  it('JENTRYROW-003: unreadable JSON no longer throws: it reads as empty and is logged', () => {
+    const wire = decodeEntryRow(row({ tags: '{oops', pros_cons: 'not json' }));
+    expect(wire.tags).toEqual([]);
+    expect(wire.pros_cons).toBeNull();
+    expect(logMock.logWarn).toHaveBeenCalledWith('[json] journey_entries.tags (journey entry 5): stored value is not valid JSON, using the fallback');
+  });
+});
diff --git a/server/tests/unit/nest/oauth.service.test.ts b/server/tests/unit/nest/oauth.service.test.ts
index e73032532..d03fe18cf 100644
--- a/server/tests/unit/nest/oauth.service.test.ts
+++ b/server/tests/unit/nest/oauth.service.test.ts
@@ -1419,4 +1419,28 @@ describe('admin OAuth sessions', () => {
     expect(sessions).toHaveLength(1);
     expect(sessions[0].scopes).toBeNull();
   });
+
+  it('a row with malformed scopes no longer fails the user list, the token check or the refresh: it grants nothing', async () => {
+    const { user } = createUser(testDb);
+    const created = await makeClient(user.id);
+    const client = created.client as { client_id: string; client_secret: string };
+    const tokens = await issueTokens(client.client_id, user.id, ['trips:read']);
+    await updateRows(t, OauthTokens, { user: user.id }, { scopes: 'not-json{' });
+
+    const [session] = await listOAuthSessions(user.id);
+    expect(session.scopes).toEqual([]);
+    expect((await getUserByAccessToken(tokens.access_token))?.scopes).toEqual([]);
+  });
+
+  it('a malformed consent row counts as consent to nothing, and a new grant replaces it', async () => {
+    const { user } = createUser(testDb);
+    const created = await makeClient(user.id);
+    const clientId = created.client!.client_id as string;
+    await saveConsent(clientId, user.id, ['trips:read']);
+    await updateRows(t, OauthConsents, { user: user.id }, { scopes: '{broken' });
+
+    expect(await getConsent(clientId, user.id)).toEqual([]);
+    await saveConsent(clientId, user.id, ['trips:write']);
+    expect(await getConsent(clientId, user.id)).toEqual(['trips:write']);
+  });
 });
diff --git a/server/tests/unit/utils/json-column.test.ts b/server/tests/unit/utils/json-column.test.ts
new file mode 100644
index 000000000..c5f936548
--- /dev/null
+++ b/server/tests/unit/utils/json-column.test.ts
@@ -0,0 +1,118 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { z } from 'zod';
+
+const logMock = vi.hoisted(() => ({ logInfo: vi.fn(), logError: vi.fn(), logWarn: vi.fn(), logDebug: vi.fn() }));
+vi.mock('../../../src/nest/audit/audit-log.logger', () => logMock);
+
+import { decodeJson, decodeJsonResult, encodeJson, logJsonFailure, type JsonColumn } from '../../../src/utils/json-column';
+import {
+  COLLAB_POLL_OPTIONS,
+  JOURNEY_ENTRY_PROS_CONS,
+  JOURNEY_ENTRY_TAGS,
+  MCP_TOKEN_API_SCOPES,
+  OAUTH_CLIENT_ALLOWED_SCOPES,
+  OAUTH_CLIENT_REDIRECT_URIS,
+  OAUTH_CONSENT_SCOPES,
+  OAUTH_TOKEN_SCOPES,
+  RESERVATION_METADATA,
+  USER_MFA_BACKUP_CODES,
+} from '../../../src/db/json-columns';
+
+const LIST: JsonColumn<string[]> = { column: 't.list', schema: z.array(z.string()), fallback: () => [] };
+
+beforeEach(() => vi.clearAllMocks());
+
+describe('decodeJsonResult', () => {
+  it('JSONCOL-001: decodes text of the right shape', () => {
+    expect(decodeJsonResult(LIST, '["a","b"]')).toEqual({ ok: true, value: ['a', 'b'] });
+  });
+
+  it('JSONCOL-002: names why a value did not decode', () => {
+    expect(decodeJsonResult(LIST, null)).toEqual({ ok: false, reason: 'empty' });
+    expect(decodeJsonResult(LIST, undefined)).toEqual({ ok: false, reason: 'empty' });
+    expect(decodeJsonResult(LIST, '')).toEqual({ ok: false, reason: 'empty' });
+    expect(decodeJsonResult(LIST, '{not json')).toEqual({ ok: false, reason: 'invalid-json' });
+    expect(decodeJsonResult(LIST, '{"a":1}')).toEqual({ ok: false, reason: 'schema' });
+  });
+
+  it('JSONCOL-003: checks a value a driver handed back already parsed', () => {
+    expect(decodeJsonResult(LIST, ['x'])).toEqual({ ok: true, value: ['x'] });
+    expect(decodeJsonResult(LIST, { a: 1 })).toEqual({ ok: false, reason: 'schema' });
+  });
+
+  it('JSONCOL-004: unwraps one level of double encoding only where the column says so', () => {
+    const doubled = JSON.stringify(JSON.stringify({ price: '12' }));
+    expect(decodeJsonResult(RESERVATION_METADATA, doubled)).toEqual({ ok: true, value: { price: '12' } });
+    expect(decodeJsonResult(LIST, JSON.stringify(JSON.stringify(['a'])))).toEqual({ ok: false, reason: 'schema' });
+    expect(decodeJsonResult(RESERVATION_METADATA, JSON.stringify('{broken'))).toEqual({ ok: false, reason: 'invalid-json' });
+  });
+});
+
+describe('decodeJson', () => {
+  it('JSONCOL-010: returns the decoded value without logging', () => {
+    expect(decodeJson(LIST, '["a"]')).toEqual(['a']);
+    expect(logMock.logWarn).not.toHaveBeenCalled();
+  });
+
+  it('JSONCOL-011: an empty column falls back quietly', () => {
+    expect(decodeJson(LIST, null)).toEqual([]);
+    expect(logMock.logWarn).not.toHaveBeenCalled();
+  });
+
+  it('JSONCOL-012: broken text and the wrong shape fall back and are logged with the column and context', () => {
+    expect(decodeJson(LIST, '{not json', 'row 7')).toEqual([]);
+    expect(logMock.logWarn).toHaveBeenLastCalledWith('[json] t.list (row 7): stored value is not valid JSON, using the fallback');
+    expect(decodeJson(LIST, '{"a":1}')).toEqual([]);
+    expect(logMock.logWarn).toHaveBeenLastCalledWith('[json] t.list: stored value has the wrong shape, using the fallback');
+  });
+
+  it('JSONCOL-013: every fallback is a fresh value', () => {
+    const a = decodeJson(RESERVATION_METADATA, null);
+    a.price = '1';
+    expect(decodeJson(RESERVATION_METADATA, null)).toEqual({});
+  });
+});
+
+describe('logJsonFailure / encodeJson', () => {
+  it('JSONCOL-020: logs the column, the context and the reason', () => {
+    logJsonFailure(LIST, 'schema');
+    expect(logMock.logWarn).toHaveBeenCalledWith('[json] t.list: stored value has the wrong shape, using the fallback');
+  });
+
+  it('JSONCOL-021: encodes a value of the right shape and refuses another', () => {
+    expect(encodeJson(LIST, ['a', 'b'])).toBe('["a","b"]');
+    expect(() => encodeJson(LIST, [1] as unknown as string[])).toThrow();
+  });
+});
+
+describe('the declared columns', () => {
+  it('JSONCOL-030: reservation metadata is an object, and anything else reads as an empty one', () => {
+    expect(decodeJson(RESERVATION_METADATA, '{"airline":"LH","legs":[1,2]}')).toEqual({ airline: 'LH', legs: [1, 2] });
+    expect(decodeJson(RESERVATION_METADATA, '[1,2]')).toEqual({});
+    expect(decodeJson(RESERVATION_METADATA, 'null')).toEqual({});
+    expect(decodeJson(RESERVATION_METADATA, '{oops')).toEqual({});
+  });
+
+  it('JSONCOL-031: the OAuth lists fail closed to an empty list', () => {
+    for (const col of [OAUTH_TOKEN_SCOPES, OAUTH_CLIENT_ALLOWED_SCOPES, OAUTH_CLIENT_REDIRECT_URIS, OAUTH_CONSENT_SCOPES]) {
+      expect(decodeJson(col, '["trips:read"]')).toEqual(['trips:read']);
+      expect(decodeJson(col, 'garbage')).toEqual([]);
+      expect(decodeJson(col, '[1]')).toEqual([]);
+    }
+  });
+
+  it('JSONCOL-032: the lenient lists keep whatever list is stored', () => {
+    expect(decodeJson(MCP_TOKEN_API_SCOPES, '["a",1]')).toEqual(['a', 1]);
+    expect(decodeJson(USER_MFA_BACKUP_CODES, '["h1",null]')).toEqual(['h1', null]);
+    expect(decodeJson(COLLAB_POLL_OPTIONS, '["Yes",{"label":"No"}]')).toEqual(['Yes', { label: 'No' }]);
+    expect(decodeJson(COLLAB_POLL_OPTIONS, '{"a":1}')).toEqual([]);
+  });
+
+  it('JSONCOL-033: journey entry tags and pros/cons', () => {
+    expect(decodeJson(JOURNEY_ENTRY_TAGS, '["beach"]')).toEqual(['beach']);
+    expect(decodeJson(JOURNEY_ENTRY_TAGS, '{bad')).toEqual([]);
+    expect(decodeJson(JOURNEY_ENTRY_PROS_CONS, '{"pros":["sun"],"cons":[]}')).toEqual({ pros: ['sun'], cons: [] });
+    expect(decodeJson(JOURNEY_ENTRY_PROS_CONS, 'null')).toBeNull();
+    expect(decodeJson(JOURNEY_ENTRY_PROS_CONS, '{bad')).toBeNull();
+  });
+});