diff --git a/apps/api/src/app.ts b/apps/api/src/app.ts
index 666fdbb..de0adeb 100644
--- a/apps/api/src/app.ts
+++ b/apps/api/src/app.ts
@@ -14,6 +14,7 @@ import { errorHandler } from './middleware/error.js';
 import authRoutes from './routes/auth.js';
 import userRoutes from './routes/users.js';
 import manufacturerRoutes from './routes/manufacturers.js';
+import partModelRoutes from './routes/part-models.js';
 import siteRoutes from './routes/sites.js';
 import roomRoutes from './routes/rooms.js';
 import binRoutes from './routes/bins.js';
@@ -79,6 +80,7 @@ app.use('/api/auth', authLimiter, authRoutes);
 app.use('/api', requireCsrf);
 app.use('/api/users', userRoutes);
 app.use('/api/manufacturers', manufacturerRoutes);
+app.use('/api/part-models', partModelRoutes);
 app.use('/api/sites', siteRoutes);
 app.use('/api/rooms', roomRoutes);
 app.use('/api/bins', binRoutes);
diff --git a/apps/api/src/controllers/hosts.ts b/apps/api/src/controllers/hosts.ts
index a0080ed..be8e229 100644
--- a/apps/api/src/controllers/hosts.ts
+++ b/apps/api/src/controllers/hosts.ts
@@ -48,6 +48,21 @@ export async function update(req: Request<{ id: string }>, res: Response, next:
   }
 }
 
+export async function listDeployedParts(
+  req: Request<{ id: string }>,
+  res: Response,
+  next: NextFunction,
+) {
+  try {
+    const parts = await prisma.$transaction((tx) =>
+      svc.listDeployedParts(tx, req.params.id),
+    );
+    res.json(parts);
+  } catch (err) {
+    next(err);
+  }
+}
+
 export async function remove(req: Request<{ id: string }>, res: Response, next: NextFunction) {
   try {
     await prisma.$transaction((tx) => svc.remove(tx, req.params.id));
diff --git a/apps/api/src/controllers/part-models.ts b/apps/api/src/controllers/part-models.ts
new file mode 100644
index 0000000..8de9cac
--- /dev/null
+++ b/apps/api/src/controllers/part-models.ts
@@ -0,0 +1,58 @@
+import type { NextFunction, Request, Response } from 'express';
+import { prisma } from '@vector/db';
+import type {
+  CreatePartModelRequest,
+  PartModelListQuery,
+  UpdatePartModelRequest,
+} from '@vector/shared';
+import * as svc from '../services/part-models.js';
+import { errors } from '../lib/http-error.js';
+
+export async function list(req: Request, res: Response, next: NextFunction) {
+  try {
+    const q = req.validated!.query as PartModelListQuery;
+    const result = await prisma.$transaction((tx) => svc.list(tx, q));
+    res.json(result);
+  } catch (err) {
+    next(err);
+  }
+}
+
+export async function get(req: Request<{ id: string }>, res: Response, next: NextFunction) {
+  try {
+    const model = await prisma.$transaction((tx) => svc.get(tx, req.params.id));
+    if (!model) throw errors.notFound('Part model');
+    res.json(model);
+  } catch (err) {
+    next(err);
+  }
+}
+
+export async function create(req: Request, res: Response, next: NextFunction) {
+  try {
+    const input = req.validated!.body as CreatePartModelRequest;
+    const model = await prisma.$transaction((tx) => svc.create(tx, input));
+    res.status(201).json(model);
+  } catch (err) {
+    next(err);
+  }
+}
+
+export async function update(req: Request<{ id: string }>, res: Response, next: NextFunction) {
+  try {
+    const input = req.validated!.body as UpdatePartModelRequest;
+    const model = await prisma.$transaction((tx) => svc.update(tx, req.params.id, input));
+    res.json(model);
+  } catch (err) {
+    next(err);
+  }
+}
+
+export async function remove(req: Request<{ id: string }>, res: Response, next: NextFunction) {
+  try {
+    await prisma.$transaction((tx) => svc.remove(tx, req.params.id));
+    res.status(204).end();
+  } catch (err) {
+    next(err);
+  }
+}
diff --git a/apps/api/src/controllers/repairs.ts b/apps/api/src/controllers/repairs.ts
index 854de66..217c19a 100644
--- a/apps/api/src/controllers/repairs.ts
+++ b/apps/api/src/controllers/repairs.ts
@@ -1,7 +1,9 @@
 import type { NextFunction, Request, Response } from 'express';
 import { prisma } from '@vector/db';
 import type {
+  CreateRepairCommentRequest,
   CreateRepairJobRequest,
+  RepairCommentListQuery,
   RepairJobListQuery,
   UpdateRepairJobRequest,
 } from '@vector/shared';
@@ -28,19 +30,6 @@ export async function get(req: Request<{ id: string }>, res: Response, next: Nex
   }
 }
 
-export async function listForPart(
-  req: Request<{ id: string }>,
-  res: Response,
-  next: NextFunction,
-) {
-  try {
-    const repairs = await prisma.$transaction((tx) => svc.listForPart(tx, req.params.id));
-    res.json(repairs);
-  } catch (err) {
-    next(err);
-  }
-}
-
 export async function create(req: Request, res: Response, next: NextFunction) {
   try {
     const input = req.validated!.body as CreateRepairJobRequest;
@@ -73,3 +62,33 @@ export async function remove(req: Request<{ id: string }>, res: Response, next:
     next(err);
   }
 }
+
+export async function listComments(
+  req: Request<{ id: string }>,
+  res: Response,
+  next: NextFunction,
+) {
+  try {
+    const q = req.validated!.query as RepairCommentListQuery;
+    const result = await prisma.$transaction((tx) => svc.listComments(tx, req.params.id, q));
+    res.json(result);
+  } catch (err) {
+    next(err);
+  }
+}
+
+export async function addComment(
+  req: Request<{ id: string }>,
+  res: Response,
+  next: NextFunction,
+) {
+  try {
+    const input = req.validated!.body as CreateRepairCommentRequest;
+    const comment = await prisma.$transaction((tx) =>
+      svc.addComment(tx, req.params.id, input, req.user ?? null),
+    );
+    res.status(201).json(comment);
+  } catch (err) {
+    next(err);
+  }
+}
diff --git a/apps/api/src/routes/hosts.ts b/apps/api/src/routes/hosts.ts
index c24ad05..f5c16fc 100644
--- a/apps/api/src/routes/hosts.ts
+++ b/apps/api/src/routes/hosts.ts
@@ -13,6 +13,7 @@ const router = Router();
 router.get('/', requireAuth, validate('query', HostListQuery), ctrl.list);
 router.post('/', requireAuth, requireRole('ADMIN'), validate('body', CreateHostRequest), ctrl.create);
 router.get('/:id', requireAuth, ctrl.get);
+router.get('/:id/deployed-parts', requireAuth, ctrl.listDeployedParts);
 router.patch('/:id', requireAuth, requireRole('ADMIN'), validate('body', UpdateHostRequest), ctrl.update);
 router.delete('/:id', requireAuth, requireRole('ADMIN'), ctrl.remove);
 
diff --git a/apps/api/src/routes/part-models.ts b/apps/api/src/routes/part-models.ts
new file mode 100644
index 0000000..8ab7298
--- /dev/null
+++ b/apps/api/src/routes/part-models.ts
@@ -0,0 +1,31 @@
+import { Router } from 'express';
+import {
+  CreatePartModelRequest,
+  PartModelListQuery,
+  UpdatePartModelRequest,
+} from '@vector/shared';
+import * as ctrl from '../controllers/part-models.js';
+import { requireAuth, requireRole } from '../middleware/auth.js';
+import { validate } from '../middleware/validate.js';
+
+const router = Router();
+
+router.get('/', requireAuth, validate('query', PartModelListQuery), ctrl.list);
+router.get('/:id', requireAuth, ctrl.get);
+router.post(
+  '/',
+  requireAuth,
+  requireRole('ADMIN'),
+  validate('body', CreatePartModelRequest),
+  ctrl.create,
+);
+router.patch(
+  '/:id',
+  requireAuth,
+  requireRole('ADMIN'),
+  validate('body', UpdatePartModelRequest),
+  ctrl.update,
+);
+router.delete('/:id', requireAuth, requireRole('ADMIN'), ctrl.remove);
+
+export default router;
diff --git a/apps/api/src/routes/parts.ts b/apps/api/src/routes/parts.ts
index d3ae6fa..4320b19 100644
--- a/apps/api/src/routes/parts.ts
+++ b/apps/api/src/routes/parts.ts
@@ -9,7 +9,6 @@ import {
 } from '@vector/shared';
 import * as ctrl from '../controllers/parts.js';
 import * as tagsCtrl from '../controllers/tags.js';
-import * as repairsCtrl from '../controllers/repairs.js';
 import { requireAuth, requireRole } from '../middleware/auth.js';
 import { validate } from '../middleware/validate.js';
 
@@ -27,6 +26,4 @@ router.get('/:id/tags', requireAuth, tagsCtrl.listForPart);
 router.post('/:id/tags', requireAuth, validate('body', AssignTagsRequest), tagsCtrl.assignToPart);
 router.delete('/:id/tags/:tagId', requireAuth, tagsCtrl.unassignFromPart);
 
-router.get('/:id/repairs', requireAuth, repairsCtrl.listForPart);
-
 export default router;
diff --git a/apps/api/src/routes/repairs.ts b/apps/api/src/routes/repairs.ts
index a08ad4b..b6a600e 100644
--- a/apps/api/src/routes/repairs.ts
+++ b/apps/api/src/routes/repairs.ts
@@ -1,6 +1,8 @@
 import { Router } from 'express';
 import {
+  CreateRepairCommentRequest,
   CreateRepairJobRequest,
+  RepairCommentListQuery,
   RepairJobListQuery,
   UpdateRepairJobRequest,
 } from '@vector/shared';
@@ -16,4 +18,17 @@ router.get('/:id', requireAuth, ctrl.get);
 router.patch('/:id', requireAuth, validate('body', UpdateRepairJobRequest), ctrl.update);
 router.delete('/:id', requireAuth, ctrl.remove);
 
+router.get(
+  '/:id/comments',
+  requireAuth,
+  validate('query', RepairCommentListQuery),
+  ctrl.listComments,
+);
+router.post(
+  '/:id/comments',
+  requireAuth,
+  validate('body', CreateRepairCommentRequest),
+  ctrl.addComment,
+);
+
 export default router;
diff --git a/apps/api/src/services/analytics.test.ts b/apps/api/src/services/analytics.test.ts
index 7a89fe8..2942869 100644
--- a/apps/api/src/services/analytics.test.ts
+++ b/apps/api/src/services/analytics.test.ts
@@ -12,10 +12,16 @@ function makeTx(args: {
     state: string;
     binId: string | null;
     createdAt: Date;
-    manufacturerId: string;
+    partModelId: string;
   }[];
   openRepairs: number;
-  eolManufacturers: { id: string; name: string; eolDate: Date | null }[];
+  eolPartModels: {
+    id: string;
+    mpn: string;
+    eolDate: Date | null;
+    manufacturerId: string;
+    manufacturer: { name: string };
+  }[];
   bins: { id: string; name: string; room: { name: string; site: { name: string } } }[];
 }): Tx {
   const tx = {
@@ -32,8 +38,8 @@ function makeTx(args: {
     repairJob: {
       count: async () => args.openRepairs,
     },
-    manufacturer: {
-      findMany: async () => args.eolManufacturers,
+    partModel: {
+      findMany: async () => args.eolPartModels,
     },
     bin: {
       findMany: async () => args.bins,
@@ -55,7 +61,7 @@ describe('analytics.dashboard', () => {
       ],
       parts: [],
       openRepairs: 4,
-      eolManufacturers: [],
+      eolPartModels: [],
       bins: [],
     });
 
@@ -73,13 +79,13 @@ describe('analytics.dashboard', () => {
       partCount: 4,
       stateRows: [],
       parts: [
-        { id: 'p1', state: 'SPARE', binId: null, createdAt: daysAgo(10), manufacturerId: 'm' },
-        { id: 'p2', state: 'SPARE', binId: null, createdAt: daysAgo(60), manufacturerId: 'm' },
-        { id: 'p3', state: 'SPARE', binId: null, createdAt: daysAgo(400), manufacturerId: 'm' },
-        { id: 'p4', state: 'SPARE', binId: null, createdAt: daysAgo(900), manufacturerId: 'm' },
+        { id: 'p1', state: 'SPARE', binId: null, createdAt: daysAgo(10), partModelId: 'pm' },
+        { id: 'p2', state: 'SPARE', binId: null, createdAt: daysAgo(60), partModelId: 'pm' },
+        { id: 'p3', state: 'SPARE', binId: null, createdAt: daysAgo(400), partModelId: 'pm' },
+        { id: 'p4', state: 'SPARE', binId: null, createdAt: daysAgo(900), partModelId: 'pm' },
       ],
       openRepairs: 0,
-      eolManufacturers: [],
+      eolPartModels: [],
       bins: [],
     });
 
@@ -98,13 +104,13 @@ describe('analytics.dashboard', () => {
       partCount: 4,
       stateRows: [],
       parts: [
-        { id: '1', state: 'SPARE', binId: 'b1', createdAt: daysAgo(1), manufacturerId: 'm' },
-        { id: '2', state: 'SPARE', binId: 'b1', createdAt: daysAgo(1), manufacturerId: 'm' },
-        { id: '3', state: 'SPARE', binId: 'b2', createdAt: daysAgo(1), manufacturerId: 'm' },
-        { id: '4', state: 'SPARE', binId: null, createdAt: daysAgo(1), manufacturerId: 'm' },
+        { id: '1', state: 'SPARE', binId: 'b1', createdAt: daysAgo(1), partModelId: 'pm' },
+        { id: '2', state: 'SPARE', binId: 'b1', createdAt: daysAgo(1), partModelId: 'pm' },
+        { id: '3', state: 'SPARE', binId: 'b2', createdAt: daysAgo(1), partModelId: 'pm' },
+        { id: '4', state: 'SPARE', binId: null, createdAt: daysAgo(1), partModelId: 'pm' },
       ],
       openRepairs: 0,
-      eolManufacturers: [],
+      eolPartModels: [],
       bins: [
         { id: 'b1', name: 'A1', room: { name: 'Lab', site: { name: 'HQ' } } },
         { id: 'b2', name: 'B2', room: { name: 'Lab', site: { name: 'HQ' } } },
@@ -118,27 +124,53 @@ describe('analytics.dashboard', () => {
     ]);
   });
 
-  it('flags manufacturers whose EOL has passed and have deployed parts', async () => {
+  it('flags part models whose EOL has passed and have deployed parts', async () => {
     const tx = makeTx({
       partCount: 3,
       stateRows: [],
       parts: [
-        { id: '1', state: 'DEPLOYED', binId: null, createdAt: daysAgo(1), manufacturerId: 'm1' },
-        { id: '2', state: 'DEPLOYED', binId: null, createdAt: daysAgo(1), manufacturerId: 'm1' },
-        { id: '3', state: 'DEPLOYED', binId: null, createdAt: daysAgo(1), manufacturerId: 'm2' },
+        { id: '1', state: 'DEPLOYED', binId: null, createdAt: daysAgo(1), partModelId: 'pm1' },
+        { id: '2', state: 'DEPLOYED', binId: null, createdAt: daysAgo(1), partModelId: 'pm1' },
+        { id: '3', state: 'DEPLOYED', binId: null, createdAt: daysAgo(1), partModelId: 'pm2' },
       ],
       openRepairs: 0,
-      eolManufacturers: [
-        { id: 'm1', name: 'Acme', eolDate: daysAgo(30) },
-        { id: 'm2', name: 'Beta', eolDate: daysAgo(10) },
-        { id: 'm3', name: 'Gamma', eolDate: daysAgo(5) },
+      eolPartModels: [
+        {
+          id: 'pm1',
+          mpn: 'ACM-100',
+          eolDate: daysAgo(30),
+          manufacturerId: 'm1',
+          manufacturer: { name: 'Acme' },
+        },
+        {
+          id: 'pm2',
+          mpn: 'BET-200',
+          eolDate: daysAgo(10),
+          manufacturerId: 'm2',
+          manufacturer: { name: 'Beta' },
+        },
+        {
+          id: 'pm3',
+          mpn: 'GAM-300',
+          eolDate: daysAgo(5),
+          manufacturerId: 'm3',
+          manufacturer: { name: 'Gamma' },
+        },
       ],
       bins: [],
     });
 
     const r = await dashboard(tx);
-    expect(r.deployedPastEol.map((m) => m.name)).toEqual(['Acme', 'Beta']);
-    expect(r.deployedPastEol[0]).toMatchObject({ manufacturerId: 'm1', deployedCount: 2 });
-    expect(r.deployedPastEol[1]).toMatchObject({ manufacturerId: 'm2', deployedCount: 1 });
+    expect(r.deployedPastEol.map((m) => m.mpn)).toEqual(['ACM-100', 'BET-200']);
+    expect(r.deployedPastEol[0]).toMatchObject({
+      partModelId: 'pm1',
+      manufacturerName: 'Acme',
+      deployedCount: 2,
+    });
+    expect(r.deployedPastEol[1]).toMatchObject({
+      partModelId: 'pm2',
+      manufacturerName: 'Beta',
+      deployedCount: 1,
+    });
   });
 });
diff --git a/apps/api/src/services/analytics.ts b/apps/api/src/services/analytics.ts
index fa41d39..d899e6e 100644
--- a/apps/api/src/services/analytics.ts
+++ b/apps/api/src/services/analytics.ts
@@ -13,7 +13,7 @@ const AGE_BUCKETS: { label: string; maxDays: number | null }[] = [
 ];
 
 export async function dashboard(tx: Tx): Promise<DashboardAnalytics> {
-  const [totalParts, stateRows, parts, openRepairs, manufacturersWithEol] = await Promise.all([
+  const [totalParts, stateRows, parts, openRepairs, partModelsWithEol] = await Promise.all([
     tx.part.count(),
     tx.part.groupBy({
       by: ['state'],
@@ -21,12 +21,18 @@ export async function dashboard(tx: Tx): Promise<DashboardAnalytics> {
       _sum: { price: true },
     }),
     tx.part.findMany({
-      select: { id: true, state: true, binId: true, createdAt: true, manufacturerId: true },
+      select: { id: true, state: true, binId: true, createdAt: true, partModelId: true },
     }),
     tx.repairJob.count({ where: { status: { in: ['PENDING', 'IN_PROGRESS'] } } }),
-    tx.manufacturer.findMany({
+    tx.partModel.findMany({
       where: { eolDate: { not: null, lte: new Date() } },
-      select: { id: true, name: true, eolDate: true },
+      select: {
+        id: true,
+        mpn: true,
+        eolDate: true,
+        manufacturerId: true,
+        manufacturer: { select: { name: true } },
+      },
     }),
   ]);
 
@@ -69,17 +75,19 @@ export async function dashboard(tx: Tx): Promise<DashboardAnalytics> {
     count: binCounts.get(id) ?? 0,
   }));
 
-  const deployedByMfg = new Map<string, number>();
+  const deployedByModel = new Map<string, number>();
   for (const part of parts) {
     if (part.state !== 'DEPLOYED') continue;
-    deployedByMfg.set(part.manufacturerId, (deployedByMfg.get(part.manufacturerId) ?? 0) + 1);
+    deployedByModel.set(part.partModelId, (deployedByModel.get(part.partModelId) ?? 0) + 1);
   }
-  const deployedPastEol = manufacturersWithEol
+  const deployedPastEol = partModelsWithEol
     .map((m) => ({
-      manufacturerId: m.id,
-      name: m.name,
-      eolDate: m.eolDate ? m.eolDate.toISOString() : null,
-      deployedCount: deployedByMfg.get(m.id) ?? 0,
+      partModelId: m.id,
+      mpn: m.mpn,
+      manufacturerId: m.manufacturerId,
+      manufacturerName: m.manufacturer.name,
+      eolDate: m.eolDate ? m.eolDate.toISOString() : '',
+      deployedCount: deployedByModel.get(m.id) ?? 0,
     }))
     .filter((m) => m.deployedCount > 0)
     .sort((a, b) => b.deployedCount - a.deployedCount);
diff --git a/apps/api/src/services/hosts.ts b/apps/api/src/services/hosts.ts
index a020e0c..cb6ebde 100644
--- a/apps/api/src/services/hosts.ts
+++ b/apps/api/src/services/hosts.ts
@@ -7,12 +7,18 @@ import type {
 import { errors } from '../lib/http-error.js';
 import type { Tx } from './types.js';
 
+function mapUniqueViolation(target: unknown): string {
+  if (Array.isArray(target) && target.includes('assetId')) return 'Asset ID already in use';
+  return 'Host name already exists';
+}
+
 export async function list(tx: Tx, q: HostListQuery) {
   const { page, pageSize, q: search } = q;
   const where: Prisma.HostWhereInput = search
     ? {
         OR: [
           { name: { contains: search } },
+          { assetId: { contains: search } },
           { location: { contains: search } },
         ],
       }
@@ -33,10 +39,19 @@ export function get(tx: Tx, id: string) {
   return tx.host.findUnique({ where: { id } });
 }
 
+export function listDeployedParts(tx: Tx, hostId: string) {
+  return tx.part.findMany({
+    where: { hostId, state: 'DEPLOYED' },
+    orderBy: { serialNumber: 'asc' },
+    include: { partModel: true, manufacturer: true },
+  });
+}
+
 export async function create(tx: Tx, input: CreateHostRequest) {
   try {
     return await tx.host.create({
       data: {
+        assetId: input.assetId,
         name: input.name,
         location: input.location ?? null,
         notes: input.notes ?? null,
@@ -44,7 +59,7 @@ export async function create(tx: Tx, input: CreateHostRequest) {
     });
   } catch (err) {
     if (err instanceof Prisma.PrismaClientKnownRequestError && err.code === 'P2002') {
-      throw errors.conflict('Host name already exists');
+      throw errors.conflict(mapUniqueViolation(err.meta?.target));
     }
     throw err;
   }
@@ -52,6 +67,7 @@ export async function create(tx: Tx, input: CreateHostRequest) {
 
 export async function update(tx: Tx, id: string, input: UpdateHostRequest) {
   const data: Prisma.HostUpdateInput = {};
+  if (input.assetId !== undefined) data.assetId = input.assetId;
   if (input.name !== undefined) data.name = input.name;
   if (input.location !== undefined) data.location = input.location;
   if (input.notes !== undefined) data.notes = input.notes;
@@ -60,7 +76,7 @@ export async function update(tx: Tx, id: string, input: UpdateHostRequest) {
   } catch (err) {
     if (err instanceof Prisma.PrismaClientKnownRequestError) {
       if (err.code === 'P2025') throw errors.notFound('Host');
-      if (err.code === 'P2002') throw errors.conflict('Host name already exists');
+      if (err.code === 'P2002') throw errors.conflict(mapUniqueViolation(err.meta?.target));
     }
     throw err;
   }
@@ -70,8 +86,9 @@ export async function remove(tx: Tx, id: string) {
   try {
     await tx.host.delete({ where: { id } });
   } catch (err) {
-    if (err instanceof Prisma.PrismaClientKnownRequestError && err.code === 'P2025') {
-      throw errors.notFound('Host');
+    if (err instanceof Prisma.PrismaClientKnownRequestError) {
+      if (err.code === 'P2025') throw errors.notFound('Host');
+      if (err.code === 'P2003') throw errors.conflict('Cannot delete: host has repairs assigned');
     }
     throw err;
   }
diff --git a/apps/api/src/services/manufacturers.ts b/apps/api/src/services/manufacturers.ts
index b13b060..82cc95e 100644
--- a/apps/api/src/services/manufacturers.ts
+++ b/apps/api/src/services/manufacturers.ts
@@ -22,12 +22,7 @@ export async function list(tx: Tx, q: PaginationQuery) {
 
 export async function create(tx: Tx, input: CreateManufacturerRequest) {
   try {
-    return await tx.manufacturer.create({
-      data: {
-        name: input.name,
-        eolDate: input.eolDate ? new Date(input.eolDate) : null,
-      },
-    });
+    return await tx.manufacturer.create({ data: { name: input.name } });
   } catch (err) {
     if (err instanceof Prisma.PrismaClientKnownRequestError && err.code === 'P2002') {
       throw errors.conflict('Manufacturer already exists');
@@ -40,7 +35,6 @@ export async function update(tx: Tx, id: string, input: UpdateManufacturerReques
   try {
     const data: Prisma.ManufacturerUpdateInput = {};
     if (input.name !== undefined) data.name = input.name;
-    if (input.eolDate !== undefined) data.eolDate = input.eolDate ? new Date(input.eolDate) : null;
     return await tx.manufacturer.update({ where: { id }, data });
   } catch (err) {
     if (err instanceof Prisma.PrismaClientKnownRequestError) {
diff --git a/apps/api/src/services/part-models.ts b/apps/api/src/services/part-models.ts
new file mode 100644
index 0000000..9f26f87
--- /dev/null
+++ b/apps/api/src/services/part-models.ts
@@ -0,0 +1,132 @@
+import { Prisma } from '@vector/db';
+import type {
+  CreatePartModelRequest,
+  PartModelListQuery,
+  UpdatePartModelRequest,
+} from '@vector/shared';
+import { errors } from '../lib/http-error.js';
+import type { Tx } from './types.js';
+
+const partModelInclude = {
+  manufacturer: true,
+  _count: { select: { parts: true } },
+} satisfies Prisma.PartModelInclude;
+
+export async function list(tx: Tx, q: PartModelListQuery) {
+  const { page, pageSize, manufacturerId, q: search, eolBefore } = q;
+  const where: Prisma.PartModelWhereInput = {};
+  if (manufacturerId) where.manufacturerId = manufacturerId;
+  if (search) where.mpn = { contains: search };
+  if (eolBefore) where.eolDate = { lte: new Date(eolBefore) };
+
+  const [data, total] = await Promise.all([
+    tx.partModel.findMany({
+      where,
+      orderBy: [{ manufacturer: { name: 'asc' } }, { mpn: 'asc' }],
+      include: partModelInclude,
+      skip: (page - 1) * pageSize,
+      take: pageSize,
+    }),
+    tx.partModel.count({ where }),
+  ]);
+  return { data, page, pageSize, total };
+}
+
+export function get(tx: Tx, id: string) {
+  return tx.partModel.findUnique({ where: { id }, include: partModelInclude });
+}
+
+export async function create(tx: Tx, input: CreatePartModelRequest) {
+  try {
+    return await tx.partModel.create({
+      data: {
+        manufacturerId: input.manufacturerId,
+        mpn: input.mpn,
+        eolDate: input.eolDate ? new Date(input.eolDate) : null,
+        notes: input.notes ?? null,
+      },
+      include: partModelInclude,
+    });
+  } catch (err) {
+    if (err instanceof Prisma.PrismaClientKnownRequestError) {
+      if (err.code === 'P2002') throw errors.conflict('MPN already exists for this manufacturer');
+      if (err.code === 'P2003') throw errors.badRequest('Manufacturer does not exist');
+    }
+    throw err;
+  }
+}
+
+export async function update(tx: Tx, id: string, input: UpdatePartModelRequest) {
+  const data: Prisma.PartModelUpdateInput = {};
+  if (input.manufacturerId !== undefined) {
+    data.manufacturer = { connect: { id: input.manufacturerId } };
+  }
+  if (input.mpn !== undefined) data.mpn = input.mpn;
+  if (input.eolDate !== undefined) {
+    data.eolDate = input.eolDate ? new Date(input.eolDate) : null;
+  }
+  if (input.notes !== undefined) data.notes = input.notes;
+  try {
+    return await tx.partModel.update({ where: { id }, data, include: partModelInclude });
+  } catch (err) {
+    if (err instanceof Prisma.PrismaClientKnownRequestError) {
+      if (err.code === 'P2025') throw errors.notFound('Part model');
+      if (err.code === 'P2002') throw errors.conflict('MPN already exists for this manufacturer');
+    }
+    throw err;
+  }
+}
+
+export async function remove(tx: Tx, id: string) {
+  try {
+    await tx.partModel.delete({ where: { id } });
+  } catch (err) {
+    if (err instanceof Prisma.PrismaClientKnownRequestError) {
+      if (err.code === 'P2025') throw errors.notFound('Part model');
+      if (err.code === 'P2003') {
+        throw errors.conflict('Cannot delete: part model has parts assigned');
+      }
+    }
+    throw err;
+  }
+}
+
+// Returns an existing PartModel for (manufacturerId, mpn) or creates one on the fly.
+// Used by the parts service so a create/update with { manufacturerId, mpn } shorthand
+// transparently provisions a catalog row.
+export async function upsertByMpn(
+  tx: Tx,
+  input: { manufacturerId: string; mpn: string },
+) {
+  const existing = await tx.partModel.findUnique({
+    where: {
+      manufacturerId_mpn: {
+        manufacturerId: input.manufacturerId,
+        mpn: input.mpn,
+      },
+    },
+  });
+  if (existing) return existing;
+  try {
+    return await tx.partModel.create({
+      data: { manufacturerId: input.manufacturerId, mpn: input.mpn },
+    });
+  } catch (err) {
+    // Lost the race; fetch the row that won.
+    if (err instanceof Prisma.PrismaClientKnownRequestError && err.code === 'P2002') {
+      const winner = await tx.partModel.findUnique({
+        where: {
+          manufacturerId_mpn: {
+            manufacturerId: input.manufacturerId,
+            mpn: input.mpn,
+          },
+        },
+      });
+      if (winner) return winner;
+    }
+    if (err instanceof Prisma.PrismaClientKnownRequestError && err.code === 'P2003') {
+      throw errors.badRequest('Manufacturer does not exist');
+    }
+    throw err;
+  }
+}
diff --git a/apps/api/src/services/parts.ts b/apps/api/src/services/parts.ts
index 90ee3b3..6a173db 100644
--- a/apps/api/src/services/parts.ts
+++ b/apps/api/src/services/parts.ts
@@ -6,13 +6,16 @@ import type {
   UpdatePartRequest,
 } from '@vector/shared';
 import { errors } from '../lib/http-error.js';
+import * as partModelsSvc from './part-models.js';
 import * as tagsSvc from './tags.js';
 import type { Actor, Tx } from './types.js';
 
 const partInclude = {
   manufacturer: true,
+  partModel: true,
   bin: { include: { room: { include: { site: true } } } },
   category: true,
+  host: true,
   tags: { include: { tag: true } },
 } satisfies Prisma.PartInclude;
 
@@ -40,26 +43,51 @@ function flattenTags(part: PartWithRelations): PartWithPath {
   return out;
 }
 
+// Resolves a CreatePartRequest's partModelId — either the explicit one passed in, or looked up
+// via (manufacturerId, mpn) shorthand that auto-creates a PartModel catalog row on first use.
+// Exactly one of those two forms is required; the zod schema enforces that at the boundary.
+async function resolvePartModel(
+  tx: Tx,
+  input: { partModelId?: string; manufacturerId?: string; mpn?: string },
+): Promise<{ partModelId: string; manufacturerId: string }> {
+  if (input.partModelId) {
+    const pm = await tx.partModel.findUnique({ where: { id: input.partModelId } });
+    if (!pm) throw errors.badRequest('Part model does not exist');
+    return { partModelId: pm.id, manufacturerId: pm.manufacturerId };
+  }
+  if (input.manufacturerId && input.mpn) {
+    const pm = await partModelsSvc.upsertByMpn(tx, {
+      manufacturerId: input.manufacturerId,
+      mpn: input.mpn,
+    });
+    return { partModelId: pm.id, manufacturerId: pm.manufacturerId };
+  }
+  throw errors.badRequest('Provide partModelId or both manufacturerId and mpn');
+}
+
 function buildWhere(q: PartListQuery): Prisma.PartWhereInput {
   const where: Prisma.PartWhereInput = {};
   if (q.state) where.state = q.state;
   if (q.binId) where.binId = q.binId;
+  if (q.hostId) where.hostId = q.hostId;
   if (q.manufacturerId) where.manufacturerId = q.manufacturerId;
+  if (q.partModelId) where.partModelId = q.partModelId;
   if (q.categoryId) where.categoryId = q.categoryId;
-  if (q.mpn) where.mpn = { contains: q.mpn };
   if (q.serialNumber) where.serialNumber = { contains: q.serialNumber };
   if (q.q) {
     where.OR = [
       { serialNumber: { contains: q.q } },
-      { mpn: { contains: q.q } },
+      { partModel: { mpn: { contains: q.q } } },
       { notes: { contains: q.q } },
     ];
   }
   if (q.tagId) where.tags = { some: { tagId: q.tagId } };
-  if (q.eolOnly) {
-    // Parts attached to a manufacturer with an EOL date that has already passed.
-    where.manufacturer = { eolDate: { lt: new Date() } };
-  }
+
+  const partModelFilter: Prisma.PartModelWhereInput = {};
+  if (q.mpn) partModelFilter.mpn = { contains: q.mpn };
+  if (q.eolOnly) partModelFilter.eolDate = { lt: new Date() };
+  if (Object.keys(partModelFilter).length > 0) where.partModel = partModelFilter;
+
   return where;
 }
 
@@ -89,17 +117,23 @@ export async function create(
   input: CreatePartRequest,
   actor: Actor | null,
 ): Promise<PartWithPath> {
+  const { partModelId, manufacturerId } = await resolvePartModel(tx, input);
+  // If caller also supplied manufacturerId explicitly, it must match the part model's.
+  if (input.manufacturerId && input.manufacturerId !== manufacturerId) {
+    throw errors.badRequest('manufacturerId does not match the selected part model');
+  }
+
   try {
     const p = await tx.part.create({
       data: {
         serialNumber: input.serialNumber,
-        mpn: input.mpn,
-        manufacturerId: input.manufacturerId,
+        partModelId,
+        manufacturerId,
         price: input.price ?? null,
         state: input.state ?? 'SPARE',
         binId: input.binId ?? null,
+        hostId: input.hostId ?? null,
         categoryId: input.categoryId ?? null,
-        replacementPartId: input.replacementPartId ?? null,
         notes: input.notes ?? null,
       },
       include: partInclude,
@@ -136,25 +170,26 @@ export async function update(
 
   const data: Prisma.PartUpdateInput = {};
   if (input.serialNumber !== undefined) data.serialNumber = input.serialNumber;
-  if (input.mpn !== undefined) data.mpn = input.mpn;
-  if (input.manufacturerId !== undefined) {
-    data.manufacturer = { connect: { id: input.manufacturerId } };
+  if (input.partModelId !== undefined) {
+    const pm = await tx.partModel.findUnique({ where: { id: input.partModelId } });
+    if (!pm) throw errors.badRequest('Part model does not exist');
+    data.partModel = { connect: { id: pm.id } };
+    // Keep denormalized manufacturerId consistent with the chosen model.
+    data.manufacturer = { connect: { id: pm.manufacturerId } };
   }
   if (input.price !== undefined) data.price = input.price;
   if (input.state !== undefined) data.state = input.state;
   if (input.binId !== undefined) {
     data.bin = input.binId ? { connect: { id: input.binId } } : { disconnect: true };
   }
+  if (input.hostId !== undefined) {
+    data.host = input.hostId ? { connect: { id: input.hostId } } : { disconnect: true };
+  }
   if (input.categoryId !== undefined) {
     data.category = input.categoryId
       ? { connect: { id: input.categoryId } }
       : { disconnect: true };
   }
-  if (input.replacementPartId !== undefined) {
-    data.replacement = input.replacementPartId
-      ? { connect: { id: input.replacementPartId } }
-      : { disconnect: true };
-  }
   if (input.notes !== undefined) data.notes = input.notes;
 
   let part: PartWithRelations;
@@ -191,14 +226,24 @@ export async function update(
       newValue: binPath(part.bin),
     });
   }
-  if (input.mpn !== undefined && input.mpn !== current.mpn) {
+  if (input.hostId !== undefined && input.hostId !== current.hostId) {
+    events.push({
+      partId: part.id,
+      userId,
+      type: 'LOCATION_CHANGED',
+      field: 'host',
+      oldValue: current.host?.name ?? null,
+      newValue: part.host?.name ?? null,
+    });
+  }
+  if (input.partModelId !== undefined && input.partModelId !== current.partModelId) {
     events.push({
       partId: part.id,
       userId,
       type: 'FIELD_UPDATED',
-      field: 'mpn',
-      oldValue: current.mpn,
-      newValue: input.mpn,
+      field: 'partModel',
+      oldValue: current.partModel.mpn,
+      newValue: part.partModel.mpn,
     });
   }
   if (input.serialNumber !== undefined && input.serialNumber !== current.serialNumber) {
@@ -211,16 +256,6 @@ export async function update(
       newValue: input.serialNumber,
     });
   }
-  if (input.manufacturerId !== undefined && input.manufacturerId !== current.manufacturerId) {
-    events.push({
-      partId: part.id,
-      userId,
-      type: 'FIELD_UPDATED',
-      field: 'manufacturer',
-      oldValue: current.manufacturer.name,
-      newValue: part.manufacturer.name,
-    });
-  }
   if (input.categoryId !== undefined && input.categoryId !== current.categoryId) {
     events.push({
       partId: part.id,
@@ -267,8 +302,11 @@ export async function remove(tx: Tx, id: string) {
   try {
     await tx.part.delete({ where: { id } });
   } catch (err) {
-    if (err instanceof Prisma.PrismaClientKnownRequestError && err.code === 'P2025') {
-      throw errors.notFound('Part');
+    if (err instanceof Prisma.PrismaClientKnownRequestError) {
+      if (err.code === 'P2025') throw errors.notFound('Part');
+      if (err.code === 'P2003') {
+        throw errors.conflict('Cannot delete: part is referenced by a repair');
+      }
     }
     throw err;
   }
@@ -295,6 +333,7 @@ export interface BulkPartsInput {
   ids: string[];
   state?: CreatePartRequest['state'];
   binId?: string | null;
+  hostId?: string | null;
   addTagIds?: string[];
   removeTagIds?: string[];
 }
@@ -312,12 +351,13 @@ export async function bulkUpdate(tx: Tx, input: BulkPartsInput, actor: Actor | n
     const patch: UpdatePartRequest = {};
     if (input.state !== undefined) patch.state = input.state;
     if (input.binId !== undefined) patch.binId = input.binId;
+    if (input.hostId !== undefined) patch.hostId = input.hostId;
     if (Object.keys(patch).length > 0) {
       await update(tx, id, patch, actor);
     }
     if (input.addTagIds || input.removeTagIds) {
       const existing = await tx.partTag.findMany({ where: { partId: id }, select: { tagId: true } });
-      let next = new Set(existing.map((r) => r.tagId));
+      const next = new Set(existing.map((r) => r.tagId));
       (input.addTagIds ?? []).forEach((t) => next.add(t));
       (input.removeTagIds ?? []).forEach((t) => next.delete(t));
       await tagsSvc.setPartTags(tx, id, [...next], actor);
diff --git a/apps/api/src/services/repairs.test.ts b/apps/api/src/services/repairs.test.ts
new file mode 100644
index 0000000..44e3334
--- /dev/null
+++ b/apps/api/src/services/repairs.test.ts
@@ -0,0 +1,225 @@
+import { describe, expect, it, vi } from 'vitest';
+import { Prisma } from '@vector/db';
+import type { Tx, Actor } from './types.js';
+import { create, addComment, listComments } from './repairs.js';
+import * as partModels from './part-models.js';
+import * as hosts from './hosts.js';
+import { AppError } from '../lib/http-error.js';
+
+const actor: Actor = { id: 'user-1', username: 'tech', role: 'ADMIN' };
+
+// Fabricate a minimal Prisma.PrismaClientKnownRequestError without requiring a live client.
+function prismaError(code: string, meta?: Record<string, unknown>) {
+  return new Prisma.PrismaClientKnownRequestError('simulated', {
+    code,
+    clientVersion: 'test',
+    meta,
+  });
+}
+
+describe('repairs.create — host membership', () => {
+  it('rejects a problem-part that is not on the chosen host', async () => {
+    const partEventCreateMany = vi.fn();
+    const repairCreate = vi.fn();
+
+    const tx = {
+      host: { findUnique: async () => ({ id: 'host-1' }) },
+      part: {
+        findMany: async () => [{ id: 'part-a', hostId: 'host-2' }],
+      },
+      repairJob: { create: repairCreate },
+      partEvent: { createMany: partEventCreateMany },
+    } as unknown as Tx;
+
+    await expect(
+      create(
+        tx,
+        { hostId: 'host-1', problem: 'fan noise', problemPartIds: ['part-a'] },
+        actor,
+      ),
+    ).rejects.toMatchObject({ status: 400 });
+
+    expect(repairCreate).not.toHaveBeenCalled();
+    expect(partEventCreateMany).not.toHaveBeenCalled();
+  });
+
+  it('succeeds with empty problemPartIds and emits no REPAIR_STARTED events', async () => {
+    const partEventCreateMany = vi.fn();
+    const repairCreate = vi.fn(async () => ({
+      id: 'repair-1',
+      hostId: 'host-1',
+      problem: 'power drops',
+      status: 'PENDING',
+      problemParts: [],
+    }));
+
+    const tx = {
+      host: { findUnique: async () => ({ id: 'host-1' }) },
+      part: { findMany: async () => [] },
+      repairJob: { create: repairCreate },
+      partEvent: { createMany: partEventCreateMany },
+    } as unknown as Tx;
+
+    const r = await create(tx, { hostId: 'host-1', problem: 'power drops' }, actor);
+    expect(r.id).toBe('repair-1');
+    expect(repairCreate).toHaveBeenCalledOnce();
+    expect(partEventCreateMany).not.toHaveBeenCalled();
+  });
+});
+
+describe('part-models.upsertByMpn', () => {
+  it('returns the existing row without creating when (manufacturerId, mpn) is taken', async () => {
+    const existing = { id: 'pm-1', manufacturerId: 'mfr-1', mpn: 'WD-1000', eolDate: null };
+    const create = vi.fn();
+    const tx = {
+      partModel: {
+        findUnique: async () => existing,
+        create,
+      },
+    } as unknown as Tx;
+
+    const r1 = await partModels.upsertByMpn(tx, { manufacturerId: 'mfr-1', mpn: 'WD-1000' });
+    const r2 = await partModels.upsertByMpn(tx, { manufacturerId: 'mfr-1', mpn: 'WD-1000' });
+    expect(r1).toBe(existing);
+    expect(r2).toBe(existing);
+    expect(create).not.toHaveBeenCalled();
+  });
+
+  it('recovers from a race by re-fetching the winning row on P2002', async () => {
+    const winner = { id: 'pm-9', manufacturerId: 'mfr-1', mpn: 'WD-1000', eolDate: null };
+    let findCall = 0;
+    const tx = {
+      partModel: {
+        findUnique: async () => {
+          findCall += 1;
+          if (findCall === 1) return null;
+          return winner;
+        },
+        create: async () => {
+          throw prismaError('P2002');
+        },
+      },
+    } as unknown as Tx;
+
+    const r = await partModels.upsertByMpn(tx, { manufacturerId: 'mfr-1', mpn: 'WD-1000' });
+    expect(r).toBe(winner);
+  });
+});
+
+describe('hosts.create — assetId uniqueness', () => {
+  it('surfaces a P2002 on assetId as a 409 with the Asset ID message', async () => {
+    const tx = {
+      host: {
+        create: async () => {
+          throw prismaError('P2002', { target: ['assetId'] });
+        },
+      },
+    } as unknown as Tx;
+
+    await expect(
+      hosts.create(tx, { assetId: 'ASSET-001', name: 'rack-1' }),
+    ).rejects.toMatchObject({ status: 409, message: 'Asset ID already in use' });
+  });
+
+  it('falls through to the name-uniqueness message for other unique targets', async () => {
+    const tx = {
+      host: {
+        create: async () => {
+          throw prismaError('P2002', { target: ['name'] });
+        },
+      },
+    } as unknown as Tx;
+
+    await expect(
+      hosts.create(tx, { assetId: 'ASSET-002', name: 'rack-1' }),
+    ).rejects.toMatchObject({ status: 409, message: 'Host name already exists' });
+  });
+});
+
+describe('repairs.addComment / listComments', () => {
+  it('stamps userId from the actor and returns it via listComments', async () => {
+    const stored: {
+      id: string;
+      repairJobId: string;
+      userId: string | null;
+      content: string;
+      createdAt: Date;
+      user: { id: string; username: string } | null;
+    }[] = [];
+    let nextId = 1;
+
+    const tx = {
+      repairJob: {
+        findUnique: async ({ include }: { include?: unknown }) => {
+          if (include) return { id: 'repair-1', problemParts: [] };
+          return { id: 'repair-1' };
+        },
+      },
+      repairComment: {
+        create: async ({ data }: { data: { repairJobId: string; userId: string | null; content: string } }) => {
+          const row = {
+            id: `c-${nextId++}`,
+            repairJobId: data.repairJobId,
+            userId: data.userId,
+            content: data.content,
+            createdAt: new Date(),
+            user: data.userId ? { id: data.userId, username: actor.username } : null,
+          };
+          stored.push(row);
+          return row;
+        },
+        findMany: async () => stored,
+        count: async () => stored.length,
+      },
+      partEvent: { createMany: vi.fn() },
+    } as unknown as Tx;
+
+    const created = await addComment(tx, 'repair-1', { content: 'Checked fans' }, actor);
+    expect(created.userId).toBe(actor.id);
+
+    const page = await listComments(tx, 'repair-1', { page: 1, pageSize: 20 });
+    expect(page.total).toBe(1);
+    expect(page.data[0]?.userId).toBe(actor.id);
+    expect(page.data[0]?.content).toBe('Checked fans');
+  });
+
+  it('emits a REPAIR_COMMENTED PartEvent for each problem part', async () => {
+    const partEventCreateMany = vi.fn();
+    const tx = {
+      repairJob: {
+        findUnique: async () => ({
+          id: 'repair-1',
+          problemParts: [{ partId: 'part-a' }, { partId: 'part-b' }],
+        }),
+      },
+      repairComment: {
+        create: async ({ data }: { data: { repairJobId: string; userId: string | null; content: string } }) => ({
+          id: 'c-1',
+          ...data,
+          createdAt: new Date(),
+          user: null,
+        }),
+      },
+      partEvent: { createMany: partEventCreateMany },
+    } as unknown as Tx;
+
+    await addComment(tx, 'repair-1', { content: 'ping' }, actor);
+    expect(partEventCreateMany).toHaveBeenCalledOnce();
+    const call = partEventCreateMany.mock.calls[0]![0] as {
+      data: { partId: string; type: string; userId: string | null }[];
+    };
+    expect(call.data.map((d) => d.partId)).toEqual(['part-a', 'part-b']);
+    expect(call.data.every((d) => d.type === 'REPAIR_COMMENTED')).toBe(true);
+    expect(call.data.every((d) => d.userId === actor.id)).toBe(true);
+  });
+
+  it('returns 404 when the repair does not exist', async () => {
+    const tx = {
+      repairJob: { findUnique: async () => null },
+    } as unknown as Tx;
+
+    await expect(
+      addComment(tx, 'missing', { content: 'hi' }, actor),
+    ).rejects.toBeInstanceOf(AppError);
+  });
+});
diff --git a/apps/api/src/services/repairs.ts b/apps/api/src/services/repairs.ts
index c8ab36f..961fef6 100644
--- a/apps/api/src/services/repairs.ts
+++ b/apps/api/src/services/repairs.ts
@@ -1,6 +1,8 @@
 import { Prisma } from '@vector/db';
 import type {
+  CreateRepairCommentRequest,
   CreateRepairJobRequest,
+  RepairCommentListQuery,
   RepairJobListQuery,
   UpdateRepairJobRequest,
 } from '@vector/shared';
@@ -8,21 +10,29 @@ import { errors } from '../lib/http-error.js';
 import type { Actor, Tx } from './types.js';
 
 const repairInclude = {
-  part: {
-    include: { manufacturer: true },
-  },
   host: true,
   assignee: { select: { id: true, username: true, email: true, role: true } },
+  problemParts: {
+    include: {
+      part: {
+        include: { partModel: true, manufacturer: true },
+      },
+    },
+  },
 } satisfies Prisma.RepairJobInclude;
 
+const commentInclude = {
+  user: { select: { id: true, username: true } },
+} satisfies Prisma.RepairCommentInclude;
+
 export async function list(tx: Tx, q: RepairJobListQuery) {
-  const { page, pageSize, status, partId, hostId, assigneeId, openOnly } = q;
+  const { page, pageSize, status, hostId, assigneeId, openOnly, problemPartId } = q;
   const where: Prisma.RepairJobWhereInput = {};
   if (status) where.status = status;
-  if (partId) where.partId = partId;
   if (hostId) where.hostId = hostId;
   if (assigneeId) where.assigneeId = assigneeId;
   if (openOnly) where.status = { in: ['PENDING', 'IN_PROGRESS'] };
+  if (problemPartId) where.problemParts = { some: { partId: problemPartId } };
 
   const [data, total] = await Promise.all([
     tx.repairJob.findMany({
@@ -41,45 +51,73 @@ export function get(tx: Tx, id: string) {
   return tx.repairJob.findUnique({ where: { id }, include: repairInclude });
 }
 
-export function listForPart(tx: Tx, partId: string) {
+export function listForHost(tx: Tx, hostId: string) {
   return tx.repairJob.findMany({
-    where: { partId },
+    where: { hostId },
     orderBy: { openedAt: 'desc' },
     include: repairInclude,
   });
 }
 
+// Validates that the submitted problem-part ids are all attached to the named host.
+// Parts that aren't on the host, or that don't exist, cause the whole repair create/update to fail
+// — no silent skipping. Parts can be in any state (a repair can target a SPARE that was tagged as
+// faulty during intake); the host-membership check is what matters.
+async function validateProblemParts(tx: Tx, hostId: string, partIds: string[] | undefined) {
+  if (!partIds || partIds.length === 0) return;
+  const uniqueIds = [...new Set(partIds)];
+  const rows = await tx.part.findMany({
+    where: { id: { in: uniqueIds } },
+    select: { id: true, hostId: true },
+  });
+  const found = new Map(rows.map((r) => [r.id, r]));
+  for (const id of uniqueIds) {
+    const row = found.get(id);
+    if (!row) throw errors.badRequest(`Part ${id} does not exist`);
+    if (row.hostId !== hostId) {
+      throw errors.badRequest(`Part ${id} is not on the selected host`);
+    }
+  }
+}
+
 export async function create(
   tx: Tx,
   input: CreateRepairJobRequest,
   actor: Actor | null,
 ) {
-  const part = await tx.part.findUnique({ where: { id: input.partId } });
-  if (!part) throw errors.notFound('Part');
+  const host = await tx.host.findUnique({ where: { id: input.hostId } });
+  if (!host) throw errors.notFound('Host');
+
+  await validateProblemParts(tx, input.hostId, input.problemPartIds);
 
   try {
     const repair = await tx.repairJob.create({
       data: {
-        partId: input.partId,
-        hostId: input.hostId ?? null,
+        hostId: input.hostId,
         assigneeId: input.assigneeId ?? null,
         notes: input.notes ?? null,
+        problem: input.problem,
         status: 'PENDING',
+        problemParts: input.problemPartIds && input.problemPartIds.length > 0
+          ? { create: [...new Set(input.problemPartIds)].map((partId) => ({ partId })) }
+          : undefined,
       },
       include: repairInclude,
     });
-    await tx.partEvent.create({
-      data: {
-        partId: part.id,
-        userId: actor?.id ?? null,
-        type: 'REPAIR_STARTED',
-        newValue: repair.id,
-      },
-    });
+    if (input.problemPartIds && input.problemPartIds.length > 0) {
+      await tx.partEvent.createMany({
+        data: [...new Set(input.problemPartIds)].map((partId) => ({
+          partId,
+          userId: actor?.id ?? null,
+          type: 'REPAIR_STARTED',
+          newValue: repair.id,
+        })),
+      });
+    }
     return repair;
   } catch (err) {
     if (err instanceof Prisma.PrismaClientKnownRequestError && err.code === 'P2003') {
-      throw errors.badRequest('Invalid host or assignee id');
+      throw errors.badRequest('Invalid host, assignee, or part id');
     }
     throw err;
   }
@@ -91,21 +129,25 @@ export async function update(
   input: UpdateRepairJobRequest,
   actor: Actor | null,
 ) {
-  const current = await tx.repairJob.findUnique({ where: { id } });
+  const current = await tx.repairJob.findUnique({
+    where: { id },
+    include: { problemParts: { select: { partId: true } }, host: true },
+  });
   if (!current) throw errors.notFound('Repair');
 
   const data: Prisma.RepairJobUpdateInput = {};
+  let terminalTransition: 'COMPLETED' | 'CANCELLED' | null = null;
   if (input.status !== undefined && input.status !== current.status) {
     data.status = input.status;
-    // closedAt follows terminal status transitions.
     const nowTerminal = input.status === 'COMPLETED' || input.status === 'CANCELLED';
     const wasTerminal = current.status === 'COMPLETED' || current.status === 'CANCELLED';
-    if (nowTerminal && !wasTerminal) data.closedAt = new Date();
+    if (nowTerminal && !wasTerminal) {
+      data.closedAt = new Date();
+      terminalTransition = input.status as 'COMPLETED' | 'CANCELLED';
+    }
     if (!nowTerminal && wasTerminal) data.closedAt = null;
   }
-  if (input.hostId !== undefined) {
-    data.host = input.hostId ? { connect: { id: input.hostId } } : { disconnect: true };
-  }
+  if (input.problem !== undefined) data.problem = input.problem;
   if (input.assigneeId !== undefined) {
     data.assignee = input.assigneeId
       ? { connect: { id: input.assigneeId } }
@@ -113,22 +155,56 @@ export async function update(
   }
   if (input.notes !== undefined) data.notes = input.notes;
 
+  // Problem-parts follow full-replace semantics: the request carries the final desired set.
+  let addedPartIds: string[] = [];
+  if (input.problemPartIds !== undefined) {
+    await validateProblemParts(tx, current.hostId, input.problemPartIds);
+    const existing = new Set(current.problemParts.map((p) => p.partId));
+    const desired = new Set(input.problemPartIds);
+    addedPartIds = [...desired].filter((p) => !existing.has(p));
+    const removed = [...existing].filter((p) => !desired.has(p));
+    if (removed.length > 0) {
+      await tx.repairJobPart.deleteMany({
+        where: { repairJobId: id, partId: { in: removed } },
+      });
+    }
+    if (addedPartIds.length > 0) {
+      await tx.repairJobPart.createMany({
+        data: addedPartIds.map((partId) => ({ repairJobId: id, partId })),
+      });
+    }
+  }
+
   const repair = await tx.repairJob.update({
     where: { id },
     data,
     include: repairInclude,
   });
 
-  if (input.status === 'COMPLETED' && current.status !== 'COMPLETED') {
-    await tx.partEvent.create({
-      data: {
-        partId: repair.partId,
-        userId: actor?.id ?? null,
-        type: 'REPAIR_COMPLETED',
+  const userId = actor?.id ?? null;
+  if (addedPartIds.length > 0) {
+    await tx.partEvent.createMany({
+      data: addedPartIds.map((partId) => ({
+        partId,
+        userId,
+        type: 'REPAIR_STARTED',
         newValue: repair.id,
-      },
+      })),
     });
   }
+  if (terminalTransition !== null) {
+    const partIds = repair.problemParts.map((p) => p.partId);
+    if (partIds.length > 0) {
+      await tx.partEvent.createMany({
+        data: partIds.map((partId) => ({
+          partId,
+          userId,
+          type: terminalTransition === 'COMPLETED' ? 'REPAIR_COMPLETED' : 'REPAIR_CANCELLED',
+          newValue: repair.id,
+        })),
+      });
+    }
+  }
 
   return repair;
 }
@@ -143,3 +219,57 @@ export async function remove(tx: Tx, id: string) {
     throw err;
   }
 }
+
+export async function listComments(tx: Tx, repairJobId: string, q: RepairCommentListQuery) {
+  const { page, pageSize } = q;
+  const repair = await tx.repairJob.findUnique({ where: { id: repairJobId }, select: { id: true } });
+  if (!repair) throw errors.notFound('Repair');
+  const [data, total] = await Promise.all([
+    tx.repairComment.findMany({
+      where: { repairJobId },
+      orderBy: { createdAt: 'asc' },
+      include: commentInclude,
+      skip: (page - 1) * pageSize,
+      take: pageSize,
+    }),
+    tx.repairComment.count({ where: { repairJobId } }),
+  ]);
+  return { data, page, pageSize, total };
+}
+
+export async function addComment(
+  tx: Tx,
+  repairJobId: string,
+  input: CreateRepairCommentRequest,
+  actor: Actor | null,
+) {
+  const repair = await tx.repairJob.findUnique({
+    where: { id: repairJobId },
+    include: { problemParts: { select: { partId: true } } },
+  });
+  if (!repair) throw errors.notFound('Repair');
+
+  const comment = await tx.repairComment.create({
+    data: {
+      repairJobId,
+      userId: actor?.id ?? null,
+      content: input.content,
+    },
+    include: commentInclude,
+  });
+
+  // Surface the comment on each problem-part's timeline so a part owner sees the activity
+  // without having to navigate through to the repair.
+  if (repair.problemParts.length > 0) {
+    await tx.partEvent.createMany({
+      data: repair.problemParts.map((p) => ({
+        partId: p.partId,
+        userId: actor?.id ?? null,
+        type: 'REPAIR_COMMENTED',
+        newValue: repair.id,
+      })),
+    });
+  }
+
+  return comment;
+}
diff --git a/apps/web/src/App.tsx b/apps/web/src/App.tsx
index 74202a1..9050396 100644
--- a/apps/web/src/App.tsx
+++ b/apps/web/src/App.tsx
@@ -12,7 +12,9 @@ import Parts from './pages/Parts.js';
 import PartDetail from './pages/PartDetail.js';
 import Locations from './pages/Locations.js';
 import Manufacturers from './pages/Manufacturers.js';
+import PartModels from './pages/PartModels.js';
 import Repairs from './pages/Repairs.js';
+import RepairDetail from './pages/RepairDetail.js';
 import Hosts from './pages/Hosts.js';
 import Users from './pages/admin/Users.js';
 import Webhooks from './pages/admin/Webhooks.js';
@@ -54,7 +56,9 @@ export default function App() {
                     <Route path="/parts/:id" element={<PartDetail />} />
                     <Route path="/locations" element={<Locations />} />
                     <Route path="/manufacturers" element={<Manufacturers />} />
+                    <Route path="/part-models" element={<PartModels />} />
                     <Route path="/repairs" element={<Repairs />} />
+                    <Route path="/repairs/:id" element={<RepairDetail />} />
                     <Route path="/hosts" element={<Hosts />} />
                     <Route
                       path="/admin/users"
diff --git a/apps/web/src/components/hosts/HostFormDialog.tsx b/apps/web/src/components/hosts/HostFormDialog.tsx
index 107e45b..69155d8 100644
--- a/apps/web/src/components/hosts/HostFormDialog.tsx
+++ b/apps/web/src/components/hosts/HostFormDialog.tsx
@@ -28,6 +28,7 @@ import { queryKeys } from '../../lib/queryKeys.js';
 import type { Host } from '../../lib/api/types.js';
 
 const Schema = z.object({
+  assetId: z.string().trim().min(1, 'Required').max(64),
   name: z.string().min(1, 'Required').max(128),
   location: z.string().max(256).optional(),
   notes: z.string().max(4096).optional(),
@@ -46,12 +47,13 @@ export function HostFormDialog({ open, onOpenChange, host }: HostFormDialogProps
 
   const form = useForm<Values>({
     resolver: zodResolver(Schema),
-    defaultValues: { name: '', location: '', notes: '' },
+    defaultValues: { assetId: '', name: '', location: '', notes: '' },
   });
 
   useEffect(() => {
     if (!open) return;
     form.reset({
+      assetId: host?.assetId ?? '',
       name: host?.name ?? '',
       location: host?.location ?? '',
       notes: host?.notes ?? '',
@@ -60,12 +62,20 @@ export function HostFormDialog({ open, onOpenChange, host }: HostFormDialogProps
 
   const mutation = useMutation({
     mutationFn: async (values: Values) => {
-      const payload = {
+      if (editing && host) {
+        return updateHost(host.id, {
+          assetId: values.assetId,
+          name: values.name,
+          location: values.location ? values.location : null,
+          notes: values.notes ? values.notes : null,
+        });
+      }
+      return createHost({
+        assetId: values.assetId,
         name: values.name,
         location: values.location ? values.location : null,
         notes: values.notes ? values.notes : null,
-      };
-      return editing && host ? updateHost(host.id, payload) : createHost(payload);
+      });
     },
     onSuccess: () => {
       toast.success(editing ? 'Host updated' : 'Host created');
@@ -88,6 +98,19 @@ export function HostFormDialog({ open, onOpenChange, host }: HostFormDialogProps
 
         <Form {...form}>
           <form onSubmit={form.handleSubmit((v) => mutation.mutate(v))} className="space-y-3">
+            <FormField
+              control={form.control}
+              name="assetId"
+              render={({ field }) => (
+                <FormItem>
+                  <FormLabel>Asset ID</FormLabel>
+                  <FormControl>
+                    <Input autoFocus placeholder="e.g. ASSET-001" {...field} />
+                  </FormControl>
+                  <FormMessage />
+                </FormItem>
+              )}
+            />
             <FormField
               control={form.control}
               name="name"
@@ -95,7 +118,7 @@ export function HostFormDialog({ open, onOpenChange, host }: HostFormDialogProps
                 <FormItem>
                   <FormLabel>Name</FormLabel>
                   <FormControl>
-                    <Input autoFocus {...field} />
+                    <Input {...field} />
                   </FormControl>
                   <FormMessage />
                 </FormItem>
diff --git a/apps/web/src/components/layout/Sidebar.tsx b/apps/web/src/components/layout/Sidebar.tsx
index 9a3db9f..7fd8402 100644
--- a/apps/web/src/components/layout/Sidebar.tsx
+++ b/apps/web/src/components/layout/Sidebar.tsx
@@ -4,6 +4,7 @@ import {
   ChevronsLeft,
   ChevronsRight,
   LayoutDashboard,
+  Layers,
   type LucideIcon,
   MapPinned,
   Package,
@@ -25,6 +26,7 @@ interface NavItem {
 const NAV_ITEMS: NavItem[] = [
   { to: '/', label: 'Dashboard', icon: LayoutDashboard },
   { to: '/parts', label: 'Parts', icon: Package },
+  { to: '/part-models', label: 'Part models', icon: Layers },
   { to: '/locations', label: 'Locations', icon: MapPinned },
   { to: '/manufacturers', label: 'Manufacturers', icon: Boxes },
   { to: '/repairs', label: 'Repairs', icon: Wrench },
diff --git a/apps/web/src/components/manufacturers/ManufacturerFormDialog.tsx b/apps/web/src/components/manufacturers/ManufacturerFormDialog.tsx
index ccf0361..0549cc6 100644
--- a/apps/web/src/components/manufacturers/ManufacturerFormDialog.tsx
+++ b/apps/web/src/components/manufacturers/ManufacturerFormDialog.tsx
@@ -15,7 +15,6 @@ import {
   DialogTitle,
   Form,
   FormControl,
-  FormDescription,
   FormField,
   FormItem,
   FormLabel,
@@ -32,11 +31,6 @@ import type { Manufacturer } from '../../lib/api/types.js';
 
 const Schema = z.object({
   name: z.string().min(1, 'Required').max(128),
-  eolDate: z
-    .string()
-    .regex(/^\d{4}-\d{2}-\d{2}$/, 'YYYY-MM-DD')
-    .or(z.literal(''))
-    .optional(),
 });
 type Values = z.infer<typeof Schema>;
 
@@ -46,11 +40,6 @@ interface ManufacturerFormDialogProps {
   manufacturer?: Manufacturer | null;
 }
 
-function isoToDateInput(iso: string | null): string {
-  if (!iso) return '';
-  return new Date(iso).toISOString().slice(0, 10);
-}
-
 export function ManufacturerFormDialog({
   open,
   onOpenChange,
@@ -61,23 +50,17 @@ export function ManufacturerFormDialog({
 
   const form = useForm<Values>({
     resolver: zodResolver(Schema),
-    defaultValues: { name: '', eolDate: '' },
+    defaultValues: { name: '' },
   });
 
   useEffect(() => {
     if (!open) return;
-    form.reset({
-      name: manufacturer?.name ?? '',
-      eolDate: isoToDateInput(manufacturer?.eolDate ?? null),
-    });
+    form.reset({ name: manufacturer?.name ?? '' });
   }, [open, manufacturer, form]);
 
   const mutation = useMutation({
     mutationFn: async (values: Values) => {
-      const payload = {
-        name: values.name,
-        eolDate: values.eolDate ? values.eolDate : null,
-      };
+      const payload = { name: values.name };
       return editing && manufacturer
         ? updateManufacturer(manufacturer.id, payload)
         : createManufacturer(payload);
@@ -98,8 +81,8 @@ export function ManufacturerFormDialog({
           <DialogTitle>{editing ? 'Edit manufacturer' : 'New manufacturer'}</DialogTitle>
           <DialogDescription>
             {editing
-              ? 'Update this manufacturer. EOL drives replacement alerts on parts.'
-              : 'Add a manufacturer. Names must be unique.'}
+              ? 'Update the manufacturer record.'
+              : 'Add a manufacturer. Names must be unique. EOL is tracked per part model.'}
           </DialogDescription>
         </DialogHeader>
 
@@ -118,23 +101,6 @@ export function ManufacturerFormDialog({
                 </FormItem>
               )}
             />
-            <FormField
-              control={form.control}
-              name="eolDate"
-              render={({ field }) => (
-                <FormItem>
-                  <FormLabel>End-of-life date</FormLabel>
-                  <FormControl>
-                    <Input type="date" {...field} />
-                  </FormControl>
-                  <FormDescription>
-                    Optional. Parts from this manufacturer will show a replacement alert past this
-                    date.
-                  </FormDescription>
-                  <FormMessage />
-                </FormItem>
-              )}
-            />
             <DialogFooter>
               <Button
                 type="button"
diff --git a/apps/web/src/components/part-models/PartModelFormDialog.tsx b/apps/web/src/components/part-models/PartModelFormDialog.tsx
new file mode 100644
index 0000000..ab93e42
--- /dev/null
+++ b/apps/web/src/components/part-models/PartModelFormDialog.tsx
@@ -0,0 +1,207 @@
+import { useEffect } from 'react';
+import { useForm } from 'react-hook-form';
+import { zodResolver } from '@hookform/resolvers/zod';
+import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
+import { z } from 'zod';
+import { Loader2 } from 'lucide-react';
+import { toast } from 'sonner';
+import {
+  Button,
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+  Form,
+  FormControl,
+  FormDescription,
+  FormField,
+  FormItem,
+  FormLabel,
+  FormMessage,
+  Input,
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+  Textarea,
+} from '@vector/ui';
+import { createPartModel, updatePartModel } from '../../lib/api/part-models.js';
+import { listManufacturers } from '../../lib/api/manufacturers.js';
+import { ApiRequestError } from '../../lib/api/client.js';
+import { queryKeys } from '../../lib/queryKeys.js';
+import type { PartModel } from '../../lib/api/types.js';
+
+const Schema = z.object({
+  manufacturerId: z.string().uuid('Pick a manufacturer'),
+  mpn: z.string().min(1, 'Required').max(128),
+  eolDate: z
+    .string()
+    .regex(/^\d{4}-\d{2}-\d{2}$/, 'YYYY-MM-DD')
+    .or(z.literal(''))
+    .optional(),
+  notes: z.string().max(4096).optional(),
+});
+type Values = z.infer<typeof Schema>;
+
+function isoToDateInput(iso: string | null): string {
+  if (!iso) return '';
+  return new Date(iso).toISOString().slice(0, 10);
+}
+
+interface PartModelFormDialogProps {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  partModel?: PartModel | null;
+}
+
+export function PartModelFormDialog({
+  open,
+  onOpenChange,
+  partModel,
+}: PartModelFormDialogProps) {
+  const editing = Boolean(partModel);
+  const queryClient = useQueryClient();
+
+  const form = useForm<Values>({
+    resolver: zodResolver(Schema),
+    defaultValues: { manufacturerId: '', mpn: '', eolDate: '', notes: '' },
+  });
+
+  useEffect(() => {
+    if (!open) return;
+    form.reset({
+      manufacturerId: partModel?.manufacturerId ?? '',
+      mpn: partModel?.mpn ?? '',
+      eolDate: isoToDateInput(partModel?.eolDate ?? null),
+      notes: partModel?.notes ?? '',
+    });
+  }, [open, partModel, form]);
+
+  const manufacturers = useQuery({
+    queryKey: queryKeys.manufacturers.list({ pageSize: 100 }),
+    queryFn: () => listManufacturers({ pageSize: 100 }),
+    enabled: open,
+  });
+
+  const mutation = useMutation({
+    mutationFn: async (values: Values) => {
+      const payload = {
+        manufacturerId: values.manufacturerId,
+        mpn: values.mpn,
+        eolDate: values.eolDate ? values.eolDate : null,
+        notes: values.notes ? values.notes : null,
+      };
+      return editing && partModel
+        ? updatePartModel(partModel.id, payload)
+        : createPartModel(payload);
+    },
+    onSuccess: () => {
+      toast.success(editing ? 'Part model updated' : 'Part model created');
+      queryClient.invalidateQueries({ queryKey: queryKeys.partModels.all });
+      onOpenChange(false);
+    },
+    onError: (err) =>
+      toast.error(err instanceof ApiRequestError ? err.body.message : 'Save failed'),
+  });
+
+  return (
+    <Dialog open={open} onOpenChange={onOpenChange}>
+      <DialogContent className="max-w-md">
+        <DialogHeader>
+          <DialogTitle>{editing ? 'Edit part model' : 'New part model'}</DialogTitle>
+          <DialogDescription>
+            A part model (MPN) is the catalog entry that carries an end-of-life date.
+          </DialogDescription>
+        </DialogHeader>
+
+        <Form {...form}>
+          <form onSubmit={form.handleSubmit((v) => mutation.mutate(v))} className="space-y-3">
+            <FormField
+              control={form.control}
+              name="manufacturerId"
+              render={({ field }) => (
+                <FormItem>
+                  <FormLabel>Manufacturer</FormLabel>
+                  <Select value={field.value} onValueChange={field.onChange}>
+                    <FormControl>
+                      <SelectTrigger>
+                        <SelectValue placeholder="Select manufacturer" />
+                      </SelectTrigger>
+                    </FormControl>
+                    <SelectContent>
+                      {manufacturers.data?.data.map((m) => (
+                        <SelectItem key={m.id} value={m.id}>
+                          {m.name}
+                        </SelectItem>
+                      ))}
+                    </SelectContent>
+                  </Select>
+                  <FormMessage />
+                </FormItem>
+              )}
+            />
+            <FormField
+              control={form.control}
+              name="mpn"
+              render={({ field }) => (
+                <FormItem>
+                  <FormLabel>MPN</FormLabel>
+                  <FormControl>
+                    <Input autoFocus {...field} />
+                  </FormControl>
+                  <FormMessage />
+                </FormItem>
+              )}
+            />
+            <FormField
+              control={form.control}
+              name="eolDate"
+              render={({ field }) => (
+                <FormItem>
+                  <FormLabel>EOL date</FormLabel>
+                  <FormControl>
+                    <Input type="date" {...field} />
+                  </FormControl>
+                  <FormDescription>
+                    Deployed parts past this date surface on the dashboard.
+                  </FormDescription>
+                  <FormMessage />
+                </FormItem>
+              )}
+            />
+            <FormField
+              control={form.control}
+              name="notes"
+              render={({ field }) => (
+                <FormItem>
+                  <FormLabel>Notes</FormLabel>
+                  <FormControl>
+                    <Textarea rows={3} {...field} />
+                  </FormControl>
+                  <FormMessage />
+                </FormItem>
+              )}
+            />
+            <DialogFooter>
+              <Button
+                type="button"
+                variant="outline"
+                onClick={() => onOpenChange(false)}
+                disabled={mutation.isPending}
+              >
+                Cancel
+              </Button>
+              <Button type="submit" disabled={mutation.isPending}>
+                {mutation.isPending && <Loader2 className="h-4 w-4 animate-spin" />}
+                {editing ? 'Save changes' : 'Create'}
+              </Button>
+            </DialogFooter>
+          </form>
+        </Form>
+      </DialogContent>
+    </Dialog>
+  );
+}
diff --git a/apps/web/src/components/parts/PartEventTimeline.tsx b/apps/web/src/components/parts/PartEventTimeline.tsx
index 381b69e..6b4d035 100644
--- a/apps/web/src/components/parts/PartEventTimeline.tsx
+++ b/apps/web/src/components/parts/PartEventTimeline.tsx
@@ -4,10 +4,12 @@ import {
   ArrowRight,
   CheckCircle2,
   MapPin,
+  MessageSquare,
   Package,
   Pencil,
   Tag,
   Wrench,
+  XCircle,
   type LucideIcon,
 } from 'lucide-react';
 import type { PartEventType } from '@vector/shared';
@@ -22,6 +24,8 @@ const EVENT_ICON: Record<PartEventType, LucideIcon> = {
   FIELD_UPDATED: Pencil,
   REPAIR_STARTED: Wrench,
   REPAIR_COMPLETED: Wrench,
+  REPAIR_CANCELLED: XCircle,
+  REPAIR_COMMENTED: MessageSquare,
   TAG_ADDED: Tag,
   TAG_REMOVED: Tag,
 };
@@ -33,6 +37,8 @@ const EVENT_TITLE: Record<PartEventType, string> = {
   FIELD_UPDATED: 'Field updated',
   REPAIR_STARTED: 'Repair started',
   REPAIR_COMPLETED: 'Repair completed',
+  REPAIR_CANCELLED: 'Repair cancelled',
+  REPAIR_COMMENTED: 'Repair comment',
   TAG_ADDED: 'Tag added',
   TAG_REMOVED: 'Tag removed',
 };
diff --git a/apps/web/src/components/parts/PartFormDialog.tsx b/apps/web/src/components/parts/PartFormDialog.tsx
index 736452b..de70fda 100644
--- a/apps/web/src/components/parts/PartFormDialog.tsx
+++ b/apps/web/src/components/parts/PartFormDialog.tsx
@@ -80,7 +80,7 @@ export function PartFormDialog({ open, onOpenChange, part }: PartFormDialogProps
       part
         ? {
             serialNumber: part.serialNumber,
-            mpn: part.mpn,
+            mpn: part.partModel.mpn,
             manufacturerId: part.manufacturerId,
             state: part.state,
             binId: part.binId ?? '',
diff --git a/apps/web/src/components/parts/PartRepairSection.tsx b/apps/web/src/components/parts/PartRepairSection.tsx
index da0fe9a..bb452a7 100644
--- a/apps/web/src/components/parts/PartRepairSection.tsx
+++ b/apps/web/src/components/parts/PartRepairSection.tsx
@@ -1,74 +1,53 @@
-import { useState } from 'react';
 import { useQuery } from '@tanstack/react-query';
-import { Plus } from 'lucide-react';
-import { Button, Skeleton } from '@vector/ui';
-import { listRepairsForPart } from '../../lib/api/repairs.js';
+import { Link } from 'react-router-dom';
+import { Skeleton } from '@vector/ui';
+import { listRepairs } from '../../lib/api/repairs.js';
 import { queryKeys } from '../../lib/queryKeys.js';
 import { RepairStatusBadge } from '../repairs/RepairStatusBadge.js';
-import { RepairFormDialog } from '../repairs/RepairFormDialog.js';
-import type { RepairJob } from '../../lib/api/types.js';
 
 interface PartRepairSectionProps {
   partId: string;
 }
 
 export function PartRepairSection({ partId }: PartRepairSectionProps) {
-  const [createOpen, setCreateOpen] = useState(false);
-  const [editing, setEditing] = useState<RepairJob | null>(null);
   const query = useQuery({
-    queryKey: [...queryKeys.parts.detail(partId), 'repairs'],
-    queryFn: () => listRepairsForPart(partId),
+    queryKey: queryKeys.repairs.list({ problemPartId: partId, pageSize: 50 }),
+    queryFn: () => listRepairs({ problemPartId: partId, pageSize: 50 }),
   });
 
   return (
     <div className="space-y-2">
-      <div className="flex items-center justify-between">
-        <p className="text-sm font-medium">Repair history</p>
-        <Button variant="outline" size="sm" onClick={() => setCreateOpen(true)}>
-          <Plus className="h-3.5 w-3.5" />
-          Open repair
-        </Button>
-      </div>
+      <p className="text-sm font-medium">Repairs touching this part</p>
       {query.isPending ? (
         <Skeleton className="h-16 w-full" />
-      ) : !query.data || query.data.length === 0 ? (
-        <p className="text-xs text-muted-foreground">No repair jobs yet.</p>
+      ) : !query.data || query.data.data.length === 0 ? (
+        <p className="text-xs text-muted-foreground">No repairs reference this part yet.</p>
       ) : (
         <ul className="divide-y divide-border rounded-md border border-border text-sm">
-          {query.data.map((repair) => (
+          {query.data.data.map((repair) => (
             <li
               key={repair.id}
               className="flex items-center justify-between gap-3 px-3 py-2"
             >
-              <div className="flex items-center gap-2">
+              <div className="flex min-w-0 items-center gap-2">
                 <RepairStatusBadge status={repair.status} />
-                <span className="text-xs text-muted-foreground">
-                  Opened {new Date(repair.openedAt).toLocaleDateString()}
-                  {repair.host ? ` · ${repair.host.name}` : ''}
+                <Link
+                  to={`/repairs/${repair.id}`}
+                  className="truncate text-xs text-foreground hover:underline"
+                >
+                  {repair.problem}
+                </Link>
+                <span className="shrink-0 text-xs text-muted-foreground">
+                  · {repair.host.name}
                 </span>
               </div>
-              <Button
-                variant="ghost"
-                size="sm"
-                className="h-7 px-2 text-xs"
-                onClick={() => setEditing(repair)}
-              >
-                Edit
-              </Button>
+              <span className="text-xs text-muted-foreground">
+                {new Date(repair.openedAt).toLocaleDateString()}
+              </span>
             </li>
           ))}
         </ul>
       )}
-      <RepairFormDialog
-        open={createOpen}
-        onOpenChange={setCreateOpen}
-        defaultPartId={partId}
-      />
-      <RepairFormDialog
-        open={Boolean(editing)}
-        onOpenChange={(o) => !o && setEditing(null)}
-        repair={editing}
-      />
     </div>
   );
 }
diff --git a/apps/web/src/components/repairs/RepairCommentThread.tsx b/apps/web/src/components/repairs/RepairCommentThread.tsx
new file mode 100644
index 0000000..3b3488e
--- /dev/null
+++ b/apps/web/src/components/repairs/RepairCommentThread.tsx
@@ -0,0 +1,118 @@
+import { useState } from 'react';
+import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
+import { Loader2, Send } from 'lucide-react';
+import { toast } from 'sonner';
+import { Button, Skeleton, Textarea } from '@vector/ui';
+import { addRepairComment, listRepairComments } from '../../lib/api/repairs.js';
+import { ApiRequestError } from '../../lib/api/client.js';
+import { queryKeys } from '../../lib/queryKeys.js';
+
+function formatWhen(iso: string) {
+  return new Date(iso).toLocaleString(undefined, {
+    month: 'short',
+    day: 'numeric',
+    year: 'numeric',
+    hour: '2-digit',
+    minute: '2-digit',
+  });
+}
+
+function initialsOf(username: string | undefined | null): string {
+  if (!username) return '?';
+  return username.slice(0, 2).toUpperCase();
+}
+
+export function RepairCommentThread({ repairId }: { repairId: string }) {
+  const queryClient = useQueryClient();
+  const [content, setContent] = useState('');
+
+  const query = useQuery({
+    queryKey: queryKeys.repairs.comments(repairId),
+    queryFn: () => listRepairComments(repairId, { pageSize: 100 }),
+  });
+
+  const mutation = useMutation({
+    mutationFn: (body: string) => addRepairComment(repairId, { content: body }),
+    onSuccess: () => {
+      setContent('');
+      queryClient.invalidateQueries({ queryKey: queryKeys.repairs.comments(repairId) });
+    },
+    onError: (err) =>
+      toast.error(err instanceof ApiRequestError ? err.body.message : 'Post failed'),
+  });
+
+  const submit = () => {
+    const trimmed = content.trim();
+    if (!trimmed) return;
+    mutation.mutate(trimmed);
+  };
+
+  return (
+    <div className="space-y-4">
+      {query.isPending ? (
+        <div className="space-y-2">
+          {Array.from({ length: 3 }).map((_, i) => (
+            <Skeleton key={i} className="h-14 w-full" />
+          ))}
+        </div>
+      ) : query.isError ? (
+        <p className="text-sm text-destructive">Could not load comments.</p>
+      ) : query.data && query.data.data.length > 0 ? (
+        <ol className="space-y-3">
+          {query.data.data.map((c) => (
+            <li key={c.id} className="flex gap-3">
+              <div className="flex h-8 w-8 shrink-0 items-center justify-center rounded-full bg-accent text-[10px] font-semibold text-accent-foreground">
+                {initialsOf(c.user?.username)}
+              </div>
+              <div className="flex-1 space-y-0.5">
+                <div className="flex flex-wrap items-center gap-x-2 text-xs text-muted-foreground">
+                  <span className="font-medium text-foreground">
+                    {c.user?.username ?? 'Unknown user'}
+                  </span>
+                  <span>·</span>
+                  <span>{formatWhen(c.createdAt)}</span>
+                </div>
+                <p className="whitespace-pre-wrap text-sm text-foreground">{c.content}</p>
+              </div>
+            </li>
+          ))}
+        </ol>
+      ) : (
+        <p className="text-sm text-muted-foreground">No comments yet. Start the thread below.</p>
+      )}
+
+      <div className="space-y-2">
+        <Textarea
+          rows={3}
+          placeholder="Leave a comment..."
+          value={content}
+          onChange={(e) => setContent(e.target.value)}
+          disabled={mutation.isPending}
+          onKeyDown={(e) => {
+            if ((e.metaKey || e.ctrlKey) && e.key === 'Enter') {
+              e.preventDefault();
+              submit();
+            }
+          }}
+        />
+        <div className="flex items-center justify-between gap-2">
+          <span className="text-xs text-muted-foreground">
+            {content.length}/4000 · Ctrl/⌘+Enter to post
+          </span>
+          <Button
+            size="sm"
+            onClick={submit}
+            disabled={mutation.isPending || content.trim().length === 0}
+          >
+            {mutation.isPending ? (
+              <Loader2 className="h-3.5 w-3.5 animate-spin" />
+            ) : (
+              <Send className="h-3.5 w-3.5" />
+            )}
+            Post
+          </Button>
+        </div>
+      </div>
+    </div>
+  );
+}
diff --git a/apps/web/src/components/repairs/RepairFormDialog.tsx b/apps/web/src/components/repairs/RepairFormDialog.tsx
index 04cb2fb..148c6fd 100644
--- a/apps/web/src/components/repairs/RepairFormDialog.tsx
+++ b/apps/web/src/components/repairs/RepairFormDialog.tsx
@@ -7,6 +7,7 @@ import { Loader2 } from 'lucide-react';
 import { toast } from 'sonner';
 import {
   Button,
+  Checkbox,
   Dialog,
   DialogContent,
   DialogDescription,
@@ -25,44 +26,38 @@ import {
   SelectItem,
   SelectTrigger,
   SelectValue,
+  Skeleton,
   Textarea,
 } from '@vector/ui';
-import { createRepair, updateRepair } from '../../lib/api/repairs.js';
-import { listHosts } from '../../lib/api/hosts.js';
+import { createRepair } from '../../lib/api/repairs.js';
+import { listHosts, listHostDeployedParts } from '../../lib/api/hosts.js';
 import { ApiRequestError } from '../../lib/api/client.js';
 import { queryKeys } from '../../lib/queryKeys.js';
 import type { RepairJob } from '../../lib/api/types.js';
-import { repairStatusOptions } from './RepairStatusBadge.js';
-
-const NONE = '__none__';
 
 const CreateSchema = z.object({
-  partId: z.string().uuid('Pick a valid part id'),
-  hostId: z.string().optional(),
-  notes: z.string().max(4096).optional(),
-});
-const EditSchema = z.object({
-  status: z.enum(['PENDING', 'IN_PROGRESS', 'COMPLETED', 'CANCELLED']),
-  hostId: z.string().optional(),
+  hostId: z.string().uuid('Pick a host'),
+  problem: z.string().trim().min(1, 'Describe the problem').max(2000),
+  problemPartIds: z.array(z.string().uuid()).max(100),
   notes: z.string().max(4096).optional(),
 });
 type CreateValues = z.infer<typeof CreateSchema>;
-type EditValues = z.infer<typeof EditSchema>;
 
 interface RepairFormDialogProps {
   open: boolean;
   onOpenChange: (open: boolean) => void;
-  repair?: RepairJob | null;
-  defaultPartId?: string;
+  defaultHostId?: string;
+  defaultProblemPartIds?: string[];
+  onCreated?: (repair: RepairJob) => void;
 }
 
 export function RepairFormDialog({
   open,
   onOpenChange,
-  repair,
-  defaultPartId,
+  defaultHostId,
+  defaultProblemPartIds,
+  onCreated,
 }: RepairFormDialogProps) {
-  const editing = Boolean(repair);
   const queryClient = useQueryClient();
 
   const hostsQuery = useQuery({
@@ -71,242 +66,213 @@ export function RepairFormDialog({
     enabled: open,
   });
 
-  const createForm = useForm<CreateValues>({
+  const form = useForm<CreateValues>({
     resolver: zodResolver(CreateSchema),
-    defaultValues: { partId: '', hostId: NONE, notes: '' },
-  });
-  const editForm = useForm<EditValues>({
-    resolver: zodResolver(EditSchema),
-    defaultValues: { status: 'PENDING', hostId: NONE, notes: '' },
+    defaultValues: {
+      hostId: '',
+      problem: '',
+      problemPartIds: [],
+      notes: '',
+    },
   });
 
   useEffect(() => {
     if (!open) return;
-    if (editing && repair) {
-      editForm.reset({
-        status: repair.status,
-        hostId: repair.hostId ?? NONE,
-        notes: repair.notes ?? '',
-      });
-    } else {
-      createForm.reset({ partId: defaultPartId ?? '', hostId: NONE, notes: '' });
-    }
-  }, [open, editing, repair, defaultPartId, createForm, editForm]);
+    form.reset({
+      hostId: defaultHostId ?? '',
+      problem: '',
+      problemPartIds: defaultProblemPartIds ?? [],
+      notes: '',
+    });
+  }, [open, defaultHostId, defaultProblemPartIds, form]);
+
+  const hostId = form.watch('hostId');
+  const selectedPartIds = form.watch('problemPartIds');
+  const deployedQuery = useQuery({
+    queryKey: queryKeys.hosts.deployedParts(hostId),
+    queryFn: () => listHostDeployedParts(hostId),
+    enabled: open && Boolean(hostId),
+  });
 
   const createMutation = useMutation({
     mutationFn: async (values: CreateValues) =>
       createRepair({
-        partId: values.partId,
-        hostId: values.hostId && values.hostId !== NONE ? values.hostId : null,
+        hostId: values.hostId,
+        problem: values.problem,
+        problemPartIds:
+          values.problemPartIds.length > 0 ? values.problemPartIds : undefined,
         notes: values.notes ? values.notes : null,
       }),
-    onSuccess: () => {
+    onSuccess: (repair) => {
       toast.success('Repair opened');
       queryClient.invalidateQueries({ queryKey: queryKeys.repairs.all });
       queryClient.invalidateQueries({ queryKey: queryKeys.parts.all });
       onOpenChange(false);
+      onCreated?.(repair);
     },
     onError: (err) =>
       toast.error(err instanceof ApiRequestError ? err.body.message : 'Save failed'),
   });
 
-  const editMutation = useMutation({
-    mutationFn: async (values: EditValues) =>
-      updateRepair(repair!.id, {
-        status: values.status,
-        hostId: values.hostId && values.hostId !== NONE ? values.hostId : null,
-        notes: values.notes ? values.notes : null,
-      }),
-    onSuccess: () => {
-      toast.success('Repair updated');
-      queryClient.invalidateQueries({ queryKey: queryKeys.repairs.all });
-      queryClient.invalidateQueries({ queryKey: queryKeys.parts.all });
-      onOpenChange(false);
-    },
-    onError: (err) =>
-      toast.error(err instanceof ApiRequestError ? err.body.message : 'Save failed'),
-  });
+  const pending = createMutation.isPending;
 
-  const pending = createMutation.isPending || editMutation.isPending;
+  function togglePart(partId: string, checked: boolean) {
+    const next = checked
+      ? [...new Set([...selectedPartIds, partId])]
+      : selectedPartIds.filter((id) => id !== partId);
+    form.setValue('problemPartIds', next, { shouldValidate: true, shouldDirty: true });
+  }
 
   return (
     <Dialog open={open} onOpenChange={onOpenChange}>
-      <DialogContent className="max-w-md">
+      <DialogContent className="max-w-lg">
         <DialogHeader>
-          <DialogTitle>{editing ? 'Edit repair' : 'Open repair'}</DialogTitle>
+          <DialogTitle>Open repair</DialogTitle>
           <DialogDescription>
-            {editing
-              ? 'Advance status, re-assign the host, or update notes.'
-              : 'Open a repair job for a part. Status starts as PENDING.'}
+            Create a repair against a host. Select the deployed parts involved (optional).
           </DialogDescription>
         </DialogHeader>
 
-        {editing ? (
-          <Form {...editForm}>
-            <form
-              onSubmit={editForm.handleSubmit((v) => editMutation.mutate(v))}
-              className="space-y-3"
-            >
-              <FormField
-                control={editForm.control}
-                name="status"
-                render={({ field }) => (
-                  <FormItem>
-                    <FormLabel>Status</FormLabel>
-                    <Select onValueChange={field.onChange} value={field.value}>
-                      <FormControl>
-                        <SelectTrigger>
-                          <SelectValue />
-                        </SelectTrigger>
-                      </FormControl>
-                      <SelectContent>
-                        {repairStatusOptions.map((o) => (
-                          <SelectItem key={o.value} value={o.value}>
-                            {o.label}
-                          </SelectItem>
-                        ))}
-                      </SelectContent>
-                    </Select>
-                    <FormMessage />
-                  </FormItem>
-                )}
-              />
-              <FormField
-                control={editForm.control}
-                name="hostId"
-                render={({ field }) => (
-                  <FormItem>
-                    <FormLabel>Host</FormLabel>
-                    <Select onValueChange={field.onChange} value={field.value ?? NONE}>
-                      <FormControl>
-                        <SelectTrigger>
-                          <SelectValue placeholder="None" />
-                        </SelectTrigger>
-                      </FormControl>
-                      <SelectContent>
-                        <SelectItem value={NONE}>None</SelectItem>
-                        {hostsQuery.data?.data.map((h) => (
-                          <SelectItem key={h.id} value={h.id}>
-                            {h.name}
-                          </SelectItem>
-                        ))}
-                      </SelectContent>
-                    </Select>
-                    <FormMessage />
-                  </FormItem>
-                )}
-              />
-              <FormField
-                control={editForm.control}
-                name="notes"
-                render={({ field }) => (
-                  <FormItem>
-                    <FormLabel>Notes</FormLabel>
+        <Form {...form}>
+          <form
+            onSubmit={form.handleSubmit((v) => createMutation.mutate(v))}
+            className="space-y-3"
+          >
+            <FormField
+              control={form.control}
+              name="hostId"
+              render={({ field }) => (
+                <FormItem>
+                  <FormLabel>Host</FormLabel>
+                  <Select
+                    onValueChange={(v) => {
+                      field.onChange(v);
+                      form.setValue('problemPartIds', [], {
+                        shouldValidate: false,
+                      });
+                    }}
+                    value={field.value}
+                  >
                     <FormControl>
-                      <Textarea rows={3} {...field} />
+                      <SelectTrigger>
+                        <SelectValue placeholder="Select host" />
+                      </SelectTrigger>
                     </FormControl>
-                    <FormMessage />
-                  </FormItem>
-                )}
-              />
-              <DialogFooter>
-                <Button
-                  type="button"
-                  variant="outline"
-                  onClick={() => onOpenChange(false)}
-                  disabled={pending}
-                >
-                  Cancel
-                </Button>
-                <Button type="submit" disabled={pending}>
-                  {pending && <Loader2 className="h-4 w-4 animate-spin" />}
-                  Save changes
-                </Button>
-              </DialogFooter>
-            </form>
-          </Form>
-        ) : (
-          <Form {...createForm}>
-            <form
-              onSubmit={createForm.handleSubmit((v) => createMutation.mutate(v))}
-              className="space-y-3"
-            >
+                    <SelectContent>
+                      {hostsQuery.data?.data.map((h) => (
+                        <SelectItem key={h.id} value={h.id}>
+                          {h.assetId} — {h.name}
+                        </SelectItem>
+                      ))}
+                    </SelectContent>
+                  </Select>
+                  <FormMessage />
+                </FormItem>
+              )}
+            />
+
+            <FormField
+              control={form.control}
+              name="problem"
+              render={({ field }) => (
+                <FormItem>
+                  <FormLabel>Problem</FormLabel>
+                  <FormControl>
+                    <Textarea
+                      rows={3}
+                      placeholder="Short description of what's wrong."
+                      {...field}
+                    />
+                  </FormControl>
+                  <FormMessage />
+                </FormItem>
+              )}
+            />
+
+            {hostId && (
               <FormField
-                control={createForm.control}
-                name="partId"
-                render={({ field }) => (
+                control={form.control}
+                name="problemPartIds"
+                render={() => (
                   <FormItem>
-                    <FormLabel>Part ID</FormLabel>
-                    <FormControl>
-                      <input
-                        className="flex h-9 w-full rounded-md border border-input bg-background px-3 py-1 text-sm shadow-sm"
-                        placeholder="Part UUID"
-                        autoFocus
-                        {...field}
-                      />
-                    </FormControl>
+                    <FormLabel>Affected parts (optional)</FormLabel>
                     <FormDescription>
-                      Paste the part UUID to open a repair against it.
+                      Select deployed parts involved in this problem.
                     </FormDescription>
+                    <div className="max-h-40 overflow-y-auto rounded-md border border-border">
+                      {deployedQuery.isPending ? (
+                        <Skeleton className="m-2 h-12" />
+                      ) : !deployedQuery.data || deployedQuery.data.length === 0 ? (
+                        <p className="p-3 text-xs text-muted-foreground">
+                          No deployed parts on this host.
+                        </p>
+                      ) : (
+                        <ul className="divide-y divide-border">
+                          {deployedQuery.data.map((part) => {
+                            const checked = selectedPartIds.includes(part.id);
+                            return (
+                              <li
+                                key={part.id}
+                                className="flex items-center gap-2 px-3 py-2 text-sm"
+                              >
+                                <Checkbox
+                                  id={`pp-${part.id}`}
+                                  checked={checked}
+                                  onCheckedChange={(v) => togglePart(part.id, v === true)}
+                                />
+                                <label
+                                  htmlFor={`pp-${part.id}`}
+                                  className="flex-1 cursor-pointer select-none"
+                                >
+                                  <span className="font-mono text-xs">
+                                    {part.serialNumber}
+                                  </span>{' '}
+                                  <span className="text-xs text-muted-foreground">
+                                    {part.partModel.mpn}
+                                  </span>
+                                </label>
+                              </li>
+                            );
+                          })}
+                        </ul>
+                      )}
+                    </div>
                     <FormMessage />
                   </FormItem>
                 )}
               />
-              <FormField
-                control={createForm.control}
-                name="hostId"
-                render={({ field }) => (
-                  <FormItem>
-                    <FormLabel>Host (optional)</FormLabel>
-                    <Select onValueChange={field.onChange} value={field.value ?? NONE}>
-                      <FormControl>
-                        <SelectTrigger>
-                          <SelectValue placeholder="None" />
-                        </SelectTrigger>
-                      </FormControl>
-                      <SelectContent>
-                        <SelectItem value={NONE}>None</SelectItem>
-                        {hostsQuery.data?.data.map((h) => (
-                          <SelectItem key={h.id} value={h.id}>
-                            {h.name}
-                          </SelectItem>
-                        ))}
-                      </SelectContent>
-                    </Select>
-                    <FormMessage />
-                  </FormItem>
-                )}
-              />
-              <FormField
-                control={createForm.control}
-                name="notes"
-                render={({ field }) => (
-                  <FormItem>
-                    <FormLabel>Notes</FormLabel>
-                    <FormControl>
-                      <Textarea rows={3} {...field} />
-                    </FormControl>
-                    <FormMessage />
-                  </FormItem>
-                )}
-              />
-              <DialogFooter>
-                <Button
-                  type="button"
-                  variant="outline"
-                  onClick={() => onOpenChange(false)}
-                  disabled={pending}
-                >
-                  Cancel
-                </Button>
-                <Button type="submit" disabled={pending}>
-                  {pending && <Loader2 className="h-4 w-4 animate-spin" />}
-                  Open repair
-                </Button>
-              </DialogFooter>
-            </form>
-          </Form>
-        )}
+            )}
+
+            <FormField
+              control={form.control}
+              name="notes"
+              render={({ field }) => (
+                <FormItem>
+                  <FormLabel>Notes (optional)</FormLabel>
+                  <FormControl>
+                    <Textarea rows={2} {...field} />
+                  </FormControl>
+                  <FormMessage />
+                </FormItem>
+              )}
+            />
+
+            <DialogFooter>
+              <Button
+                type="button"
+                variant="outline"
+                onClick={() => onOpenChange(false)}
+                disabled={pending}
+              >
+                Cancel
+              </Button>
+              <Button type="submit" disabled={pending}>
+                {pending && <Loader2 className="h-4 w-4 animate-spin" />}
+                Open repair
+              </Button>
+            </DialogFooter>
+          </form>
+        </Form>
       </DialogContent>
     </Dialog>
   );
diff --git a/apps/web/src/lib/api/hosts.ts b/apps/web/src/lib/api/hosts.ts
index e39873e..3e8e71a 100644
--- a/apps/web/src/lib/api/hosts.ts
+++ b/apps/web/src/lib/api/hosts.ts
@@ -1,7 +1,7 @@
 import type { CreateHostRequest, UpdateHostRequest } from '@vector/shared';
 import { api } from './client.js';
 import { getList } from './paginated.js';
-import type { Host } from './types.js';
+import type { Host, Part } from './types.js';
 
 export type HostListFilters = {
   page?: number;
@@ -18,6 +18,11 @@ export async function getHost(id: string): Promise<Host> {
   return res.data;
 }
 
+export async function listHostDeployedParts(id: string): Promise<Part[]> {
+  const res = await api.get<Part[]>(`/hosts/${id}/deployed-parts`);
+  return res.data;
+}
+
 export async function createHost(input: CreateHostRequest): Promise<Host> {
   const res = await api.post<Host>('/hosts', input);
   return res.data;
diff --git a/apps/web/src/lib/api/part-models.ts b/apps/web/src/lib/api/part-models.ts
new file mode 100644
index 0000000..b97617a
--- /dev/null
+++ b/apps/web/src/lib/api/part-models.ts
@@ -0,0 +1,41 @@
+import type {
+  CreatePartModelRequest,
+  UpdatePartModelRequest,
+} from '@vector/shared';
+import { api } from './client.js';
+import { getList } from './paginated.js';
+import type { PartModel } from './types.js';
+
+export type PartModelListFilters = {
+  page?: number;
+  pageSize?: number;
+  manufacturerId?: string;
+  q?: string;
+  eolBefore?: string;
+};
+
+export function listPartModels(filters: PartModelListFilters = {}) {
+  return getList<PartModel>('/part-models', filters);
+}
+
+export async function getPartModel(id: string): Promise<PartModel> {
+  const res = await api.get<PartModel>(`/part-models/${id}`);
+  return res.data;
+}
+
+export async function createPartModel(input: CreatePartModelRequest): Promise<PartModel> {
+  const res = await api.post<PartModel>('/part-models', input);
+  return res.data;
+}
+
+export async function updatePartModel(
+  id: string,
+  input: UpdatePartModelRequest,
+): Promise<PartModel> {
+  const res = await api.patch<PartModel>(`/part-models/${id}`, input);
+  return res.data;
+}
+
+export async function deletePartModel(id: string): Promise<void> {
+  await api.delete(`/part-models/${id}`);
+}
diff --git a/apps/web/src/lib/api/repairs.ts b/apps/web/src/lib/api/repairs.ts
index 2426b61..18d13f9 100644
--- a/apps/web/src/lib/api/repairs.ts
+++ b/apps/web/src/lib/api/repairs.ts
@@ -1,18 +1,19 @@
 import type {
+  CreateRepairCommentRequest,
   CreateRepairJobRequest,
   RepairStatus,
   UpdateRepairJobRequest,
 } from '@vector/shared';
 import { api } from './client.js';
 import { getList } from './paginated.js';
-import type { RepairJob } from './types.js';
+import type { RepairComment, RepairJob } from './types.js';
 
 export type RepairListFilters = {
   page?: number;
   pageSize?: number;
   status?: RepairStatus;
-  partId?: string;
   hostId?: string;
+  problemPartId?: string;
   assigneeId?: string;
   openOnly?: boolean;
 };
@@ -26,11 +27,6 @@ export async function getRepair(id: string): Promise<RepairJob> {
   return res.data;
 }
 
-export async function listRepairsForPart(partId: string): Promise<RepairJob[]> {
-  const res = await api.get<RepairJob[]>(`/parts/${partId}/repairs`);
-  return res.data;
-}
-
 export async function createRepair(input: CreateRepairJobRequest): Promise<RepairJob> {
   const res = await api.post<RepairJob>('/repairs', input);
   return res.data;
@@ -47,3 +43,18 @@ export async function updateRepair(
 export async function deleteRepair(id: string): Promise<void> {
   await api.delete(`/repairs/${id}`);
 }
+
+export function listRepairComments(
+  id: string,
+  filters: { page?: number; pageSize?: number } = {},
+) {
+  return getList<RepairComment>(`/repairs/${id}/comments`, filters);
+}
+
+export async function addRepairComment(
+  id: string,
+  input: CreateRepairCommentRequest,
+): Promise<RepairComment> {
+  const res = await api.post<RepairComment>(`/repairs/${id}/comments`, input);
+  return res.data;
+}
diff --git a/apps/web/src/lib/api/types.ts b/apps/web/src/lib/api/types.ts
index fbc9f3e..0a1804b 100644
--- a/apps/web/src/lib/api/types.ts
+++ b/apps/web/src/lib/api/types.ts
@@ -6,11 +6,22 @@ import type { PartEventType, PartState, RepairStatus, Role } from '@vector/share
 export interface Manufacturer {
   id: string;
   name: string;
-  eolDate: string | null;
   createdAt: string;
   updatedAt: string;
 }
 
+export interface PartModel {
+  id: string;
+  manufacturerId: string;
+  mpn: string;
+  eolDate: string | null;
+  notes: string | null;
+  createdAt: string;
+  updatedAt: string;
+  manufacturer?: Manufacturer;
+  _count?: { parts: number };
+}
+
 export interface Site {
   id: string;
   name: string;
@@ -42,18 +53,20 @@ export interface BinWithPath extends Bin {
 export interface Part {
   id: string;
   serialNumber: string;
-  mpn: string;
+  partModelId: string;
   manufacturerId: string;
   price: number | null;
   state: PartState;
   binId: string | null;
   categoryId: string | null;
-  replacementPartId: string | null;
+  hostId: string | null;
   notes: string | null;
   createdAt: string;
   updatedAt: string;
   manufacturer: Manufacturer;
+  partModel: PartModel;
   bin: BinWithPath | null;
+  host: Host | null;
 }
 
 export interface PartEvent {
@@ -79,6 +92,7 @@ export interface User {
 
 export interface Host {
   id: string;
+  assetId: string;
   name: string;
   location: string | null;
   notes: string | null;
@@ -101,20 +115,36 @@ export interface Category {
   updatedAt: string;
 }
 
+export interface RepairJobProblemPart {
+  repairJobId: string;
+  partId: string;
+  createdAt: string;
+  part: Part;
+}
+
 export interface RepairJob {
   id: string;
-  partId: string;
-  hostId: string | null;
+  hostId: string;
   assigneeId: string | null;
   status: RepairStatus;
+  problem: string;
   notes: string | null;
   openedAt: string;
   closedAt: string | null;
   createdAt: string;
   updatedAt: string;
-  part: Part;
-  host: Host | null;
+  host: Host;
   assignee: Pick<User, 'id' | 'username' | 'email' | 'role'> | null;
+  problemParts: RepairJobProblemPart[];
+}
+
+export interface RepairComment {
+  id: string;
+  repairJobId: string;
+  userId: string | null;
+  content: string;
+  createdAt: string;
+  user: Pick<User, 'id' | 'username'> | null;
 }
 
 export interface SavedView {
diff --git a/apps/web/src/lib/queryKeys.ts b/apps/web/src/lib/queryKeys.ts
index 88b2817..f957248 100644
--- a/apps/web/src/lib/queryKeys.ts
+++ b/apps/web/src/lib/queryKeys.ts
@@ -47,12 +47,20 @@ export const queryKeys = {
     list: (filters?: Record<string, unknown>) =>
       [...queryKeys.hosts.all, 'list', filters ?? {}] as const,
     detail: (id: string) => [...queryKeys.hosts.all, 'detail', id] as const,
+    deployedParts: (id: string) => [...queryKeys.hosts.all, 'deployed-parts', id] as const,
   },
   repairs: {
     all: ['repairs'] as const,
     list: (filters?: Record<string, unknown>) =>
       [...queryKeys.repairs.all, 'list', filters ?? {}] as const,
     detail: (id: string) => [...queryKeys.repairs.all, 'detail', id] as const,
+    comments: (id: string) => [...queryKeys.repairs.all, 'comments', id] as const,
+  },
+  partModels: {
+    all: ['part-models'] as const,
+    list: (filters?: Record<string, unknown>) =>
+      [...queryKeys.partModels.all, 'list', filters ?? {}] as const,
+    detail: (id: string) => [...queryKeys.partModels.all, 'detail', id] as const,
   },
   tags: {
     all: ['tags'] as const,
diff --git a/apps/web/src/pages/Dashboard.tsx b/apps/web/src/pages/Dashboard.tsx
index ca8f990..f635409 100644
--- a/apps/web/src/pages/Dashboard.tsx
+++ b/apps/web/src/pages/Dashboard.tsx
@@ -276,28 +276,37 @@ function KpiCard({
 function PastEolBanner({
   rows,
 }: {
-  rows: { manufacturerId: string; name: string; eolDate: string | null; deployedCount: number }[];
+  rows: {
+    partModelId: string;
+    mpn: string;
+    manufacturerId: string;
+    manufacturerName: string;
+    eolDate: string;
+    deployedCount: number;
+  }[];
 }) {
   return (
     <Card className="border-warning/50 bg-warning/5">
       <CardHeader>
         <CardTitle className="flex items-center gap-2 text-base">
           <AlertTriangle className="h-4 w-4 text-warning" />
-          Deployed past manufacturer EOL
+          Deployed past part-model EOL
         </CardTitle>
         <CardDescription>
-          These manufacturers have passed their end-of-life date — plan replacements for any parts
-          still in production.
+          These MPNs have passed their end-of-life date — plan replacements for any parts still in
+          production.
         </CardDescription>
       </CardHeader>
       <CardContent className="space-y-2 pb-5">
         {rows.map((row) => (
           <div
-            key={row.manufacturerId}
+            key={row.partModelId}
             className="flex items-center justify-between rounded-md border border-border bg-background px-3 py-2 text-sm"
           >
             <div className="min-w-0">
-              <div className="truncate font-medium">{row.name}</div>
+              <div className="truncate font-medium">
+                {row.manufacturerName} · <span className="font-mono">{row.mpn}</span>
+              </div>
               {row.eolDate && (
                 <div className="text-xs text-muted-foreground">
                   EOL {new Date(row.eolDate).toLocaleDateString()}
@@ -309,7 +318,7 @@ function PastEolBanner({
                 {row.deployedCount} deployed
               </span>
               <Button asChild variant="outline" size="sm">
-                <Link to={`/parts?manufacturerId=${row.manufacturerId}&state=DEPLOYED`}>View</Link>
+                <Link to={`/parts?partModelId=${row.partModelId}&state=DEPLOYED`}>View</Link>
               </Button>
             </div>
           </div>
diff --git a/apps/web/src/pages/Hosts.tsx b/apps/web/src/pages/Hosts.tsx
index 5db2f24..5da5f00 100644
--- a/apps/web/src/pages/Hosts.tsx
+++ b/apps/web/src/pages/Hosts.tsx
@@ -43,6 +43,13 @@ export default function Hosts() {
 
   const columns = useMemo<ColumnDef<Host>[]>(
     () => [
+      {
+        accessorKey: 'assetId',
+        header: 'Asset ID',
+        cell: ({ row }) => (
+          <span className="font-mono text-xs font-medium">{row.original.assetId}</span>
+        ),
+      },
       {
         accessorKey: 'name',
         header: 'Name',
diff --git a/apps/web/src/pages/Manufacturers.tsx b/apps/web/src/pages/Manufacturers.tsx
index c125c49..92477fb 100644
--- a/apps/web/src/pages/Manufacturers.tsx
+++ b/apps/web/src/pages/Manufacturers.tsx
@@ -4,7 +4,6 @@ import { useMutation, useQueryClient } from '@tanstack/react-query';
 import { Building, Edit, MoreHorizontal, Plus, Trash2 } from 'lucide-react';
 import { toast } from 'sonner';
 import {
-  Badge,
   Button,
   DropdownMenu,
   DropdownMenuContent,
@@ -49,20 +48,6 @@ export default function Manufacturers() {
         header: 'Name',
         cell: ({ row }) => <span className="font-medium">{row.original.name}</span>,
       },
-      {
-        accessorKey: 'eolDate',
-        header: 'EOL',
-        cell: ({ row }) => {
-          if (!row.original.eolDate) {
-            return <span className="text-xs text-muted-foreground">—</span>;
-          }
-          const d = new Date(row.original.eolDate);
-          const past = d.getTime() < Date.now();
-          return (
-            <Badge variant={past ? 'warning' : 'outline'}>{d.toLocaleDateString()}</Badge>
-          );
-        },
-      },
       {
         accessorKey: 'createdAt',
         header: 'Added',
@@ -109,7 +94,7 @@ export default function Manufacturers() {
     <div className="space-y-5">
       <PageHeader
         title="Manufacturers"
-        description="Vendors and their end-of-life dates."
+        description="Vendors. EOL is tracked per part model (see Catalog → Part models)."
         actions={
           isAdmin && (
             <Button onClick={() => setCreateOpen(true)}>
diff --git a/apps/web/src/pages/PartDetail.tsx b/apps/web/src/pages/PartDetail.tsx
index a9d885f..c6d0bd9 100644
--- a/apps/web/src/pages/PartDetail.tsx
+++ b/apps/web/src/pages/PartDetail.tsx
@@ -89,7 +89,7 @@ export default function PartDetail() {
     );
   }
 
-  const eolDate = part.manufacturer.eolDate ? new Date(part.manufacturer.eolDate) : null;
+  const eolDate = part.partModel.eolDate ? new Date(part.partModel.eolDate) : null;
   const pastEol = eolDate ? eolDate.getTime() < Date.now() : false;
 
   return (
@@ -102,7 +102,7 @@ export default function PartDetail() {
           <div>
             <h1 className="font-mono text-lg font-semibold tracking-tight">{part.serialNumber}</h1>
             <p className="text-xs text-muted-foreground">
-              {part.manufacturer.name} · {part.mpn}
+              {part.manufacturer.name} · {part.partModel.mpn}
             </p>
           </div>
         </div>
@@ -132,7 +132,7 @@ export default function PartDetail() {
             <AlertTriangle className="mt-0.5 h-4 w-4 text-warning" />
             <div className="text-sm">
               <span className="font-medium text-foreground">
-                {part.manufacturer.name} reached EOL {eolDate.toLocaleDateString()}.
+                {part.partModel.mpn} reached EOL {eolDate.toLocaleDateString()}.
               </span>{' '}
               <span className="text-muted-foreground">
                 Plan a replacement for this part.
@@ -150,7 +150,7 @@ export default function PartDetail() {
           <CardContent>
             <dl className="space-y-2">
               <DetailRow label="Serial" value={<span className="font-mono text-xs">{part.serialNumber}</span>} />
-              <DetailRow label="MPN" value={part.mpn} />
+              <DetailRow label="MPN" value={part.partModel.mpn} />
               <DetailRow
                 label="Manufacturer"
                 value={
diff --git a/apps/web/src/pages/PartModels.tsx b/apps/web/src/pages/PartModels.tsx
new file mode 100644
index 0000000..d90694f
--- /dev/null
+++ b/apps/web/src/pages/PartModels.tsx
@@ -0,0 +1,171 @@
+import { useMemo, useState } from 'react';
+import type { ColumnDef } from '@tanstack/react-table';
+import { useMutation, useQueryClient } from '@tanstack/react-query';
+import { Edit, Layers, MoreHorizontal, Plus, Trash2 } from 'lucide-react';
+import { toast } from 'sonner';
+import {
+  Badge,
+  Button,
+  DropdownMenu,
+  DropdownMenuContent,
+  DropdownMenuItem,
+  DropdownMenuSeparator,
+  DropdownMenuTrigger,
+} from '@vector/ui';
+import { PageHeader } from '../components/layout/PageHeader.js';
+import { DataTable } from '../components/data-table/DataTable.js';
+import { PartModelFormDialog } from '../components/part-models/PartModelFormDialog.js';
+import { ConfirmDialog } from '../components/ConfirmDialog.js';
+import { deletePartModel, listPartModels } from '../lib/api/part-models.js';
+import { ApiRequestError } from '../lib/api/client.js';
+import type { PartModel } from '../lib/api/types.js';
+import { queryKeys } from '../lib/queryKeys.js';
+import { useAuth } from '../contexts/AuthContext.js';
+
+export default function PartModels() {
+  const { user } = useAuth();
+  const isAdmin = user?.role === 'ADMIN';
+  const queryClient = useQueryClient();
+
+  const [createOpen, setCreateOpen] = useState(false);
+  const [editing, setEditing] = useState<PartModel | null>(null);
+  const [deleting, setDeleting] = useState<PartModel | null>(null);
+
+  const deleteMutation = useMutation({
+    mutationFn: (id: string) => deletePartModel(id),
+    onSuccess: () => {
+      toast.success('Part model deleted');
+      queryClient.invalidateQueries({ queryKey: queryKeys.partModels.all });
+      setDeleting(null);
+    },
+    onError: (err) =>
+      toast.error(err instanceof ApiRequestError ? err.body.message : 'Delete failed'),
+  });
+
+  const columns = useMemo<ColumnDef<PartModel>[]>(
+    () => [
+      {
+        accessorKey: 'manufacturer',
+        header: 'Manufacturer',
+        cell: ({ row }) => (
+          <span className="text-sm">{row.original.manufacturer?.name ?? '—'}</span>
+        ),
+      },
+      {
+        accessorKey: 'mpn',
+        header: 'MPN',
+        cell: ({ row }) => (
+          <span className="font-mono text-xs font-medium">{row.original.mpn}</span>
+        ),
+      },
+      {
+        accessorKey: 'eolDate',
+        header: 'EOL',
+        cell: ({ row }) => {
+          const iso = row.original.eolDate;
+          if (!iso) return <span className="text-sm text-muted-foreground">—</span>;
+          const pastEol = new Date(iso).getTime() <= Date.now();
+          return (
+            <div className="flex items-center gap-2">
+              <span className="text-sm">{new Date(iso).toLocaleDateString()}</span>
+              {pastEol && <Badge variant="destructive">Past EOL</Badge>}
+            </div>
+          );
+        },
+      },
+      {
+        id: 'deployedCount',
+        header: 'Deployed',
+        cell: ({ row }) => (
+          <span className="text-sm tabular-nums">{row.original._count?.parts ?? 0}</span>
+        ),
+      },
+      {
+        id: 'actions',
+        header: () => <span className="sr-only">Actions</span>,
+        size: 40,
+        cell: ({ row }) =>
+          isAdmin ? (
+            <DropdownMenu>
+              <DropdownMenuTrigger asChild>
+                <Button variant="ghost" size="icon" className="h-7 w-7">
+                  <MoreHorizontal className="h-4 w-4" />
+                </Button>
+              </DropdownMenuTrigger>
+              <DropdownMenuContent align="end" className="w-36">
+                <DropdownMenuItem onSelect={() => setEditing(row.original)}>
+                  <Edit className="h-3.5 w-3.5" />
+                  Edit
+                </DropdownMenuItem>
+                <DropdownMenuSeparator />
+                <DropdownMenuItem
+                  onSelect={() => setDeleting(row.original)}
+                  className="text-destructive focus:text-destructive"
+                >
+                  <Trash2 className="h-3.5 w-3.5" />
+                  Delete
+                </DropdownMenuItem>
+              </DropdownMenuContent>
+            </DropdownMenu>
+          ) : null,
+      },
+    ],
+    [isAdmin],
+  );
+
+  return (
+    <div className="space-y-5">
+      <PageHeader
+        title="Part models"
+        description="Catalog of MPNs. End-of-life is tracked per model and drives the past-EOL dashboard alert."
+        actions={
+          isAdmin && (
+            <Button onClick={() => setCreateOpen(true)}>
+              <Plus className="h-4 w-4" />
+              New part model
+            </Button>
+          )
+        }
+      />
+
+      <DataTable<PartModel, Record<string, never>>
+        columns={columns}
+        getRowId={(m) => m.id}
+        queryKey={(params) =>
+          queryKeys.partModels.list({ page: params.page, pageSize: params.pageSize, q: params.q })
+        }
+        queryFn={(params) =>
+          listPartModels({ page: params.page, pageSize: params.pageSize, q: params.q })
+        }
+        searchPlaceholder="Search MPN..."
+        emptyState={
+          <div className="flex flex-col items-center gap-1 py-8 text-muted-foreground">
+            <Layers className="h-6 w-6" />
+            <span className="text-sm">No part models yet.</span>
+          </div>
+        }
+      />
+
+      <PartModelFormDialog open={createOpen} onOpenChange={setCreateOpen} />
+      <PartModelFormDialog
+        open={Boolean(editing)}
+        onOpenChange={(o) => !o && setEditing(null)}
+        partModel={editing}
+      />
+      <ConfirmDialog
+        open={Boolean(deleting)}
+        onOpenChange={(o) => !o && setDeleting(null)}
+        title="Delete part model?"
+        description={
+          deleting
+            ? `Remove ${deleting.mpn}. Fails if any parts reference this model.`
+            : undefined
+        }
+        confirmLabel="Delete"
+        destructive
+        pending={deleteMutation.isPending}
+        onConfirm={() => deleting && deleteMutation.mutate(deleting.id)}
+      />
+    </div>
+  );
+}
diff --git a/apps/web/src/pages/Parts.tsx b/apps/web/src/pages/Parts.tsx
index 57e4608..eb6580f 100644
--- a/apps/web/src/pages/Parts.tsx
+++ b/apps/web/src/pages/Parts.tsx
@@ -94,9 +94,11 @@ export default function Parts() {
         ),
       },
       {
-        accessorKey: 'mpn',
+        id: 'mpn',
         header: 'MPN',
-        cell: ({ row }) => <span className="text-sm">{row.original.mpn}</span>,
+        cell: ({ row }) => (
+          <span className="text-sm font-mono">{row.original.partModel.mpn}</span>
+        ),
       },
       {
         id: 'manufacturer',
diff --git a/apps/web/src/pages/RepairDetail.tsx b/apps/web/src/pages/RepairDetail.tsx
new file mode 100644
index 0000000..079b3bf
--- /dev/null
+++ b/apps/web/src/pages/RepairDetail.tsx
@@ -0,0 +1,473 @@
+import { useEffect, useState } from 'react';
+import { Link, useNavigate, useParams } from 'react-router-dom';
+import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
+import {
+  ArrowLeft,
+  Check,
+  Loader2,
+  Pencil,
+  Plus,
+  Server,
+  Trash2,
+  X,
+} from 'lucide-react';
+import { toast } from 'sonner';
+import type { RepairStatus } from '@vector/shared';
+import {
+  Button,
+  Card,
+  CardContent,
+  CardDescription,
+  CardHeader,
+  CardTitle,
+  Checkbox,
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+  Separator,
+  Skeleton,
+  Textarea,
+} from '@vector/ui';
+import { getRepair, updateRepair } from '../lib/api/repairs.js';
+import { listHostDeployedParts } from '../lib/api/hosts.js';
+import { ApiRequestError } from '../lib/api/client.js';
+import { queryKeys } from '../lib/queryKeys.js';
+import type { RepairJob } from '../lib/api/types.js';
+import { RepairStatusBadge, repairStatusOptions } from '../components/repairs/RepairStatusBadge.js';
+import { PartStateBadge } from '../components/parts/PartStateBadge.js';
+import { RepairCommentThread } from '../components/repairs/RepairCommentThread.js';
+
+export default function RepairDetail() {
+  const { id } = useParams<{ id: string }>();
+  const navigate = useNavigate();
+  const queryClient = useQueryClient();
+
+  const { data: repair, isPending, isError, error } = useQuery({
+    queryKey: queryKeys.repairs.detail(id!),
+    queryFn: () => getRepair(id!),
+    enabled: Boolean(id),
+  });
+
+  const invalidate = () => {
+    queryClient.invalidateQueries({ queryKey: queryKeys.repairs.detail(id!) });
+    queryClient.invalidateQueries({ queryKey: queryKeys.repairs.list() });
+    queryClient.invalidateQueries({ queryKey: queryKeys.parts.all });
+  };
+
+  const statusMutation = useMutation({
+    mutationFn: (status: RepairStatus) => updateRepair(id!, { status }),
+    onSuccess: () => {
+      toast.success('Status updated');
+      invalidate();
+    },
+    onError: (err) =>
+      toast.error(err instanceof ApiRequestError ? err.body.message : 'Update failed'),
+  });
+
+  if (isPending) {
+    return (
+      <div className="space-y-4">
+        <Skeleton className="h-10 w-80" />
+        <Skeleton className="h-40 w-full" />
+        <Skeleton className="h-64 w-full" />
+      </div>
+    );
+  }
+
+  if (isError || !repair) {
+    const msg = error instanceof ApiRequestError ? error.body.message : 'Repair not found.';
+    return (
+      <Card>
+        <CardHeader>
+          <CardTitle>Repair unavailable</CardTitle>
+          <CardDescription>{msg}</CardDescription>
+        </CardHeader>
+        <CardContent>
+          <Button variant="outline" onClick={() => navigate('/repairs')}>
+            <ArrowLeft className="h-4 w-4" />
+            Back to repairs
+          </Button>
+        </CardContent>
+      </Card>
+    );
+  }
+
+  const terminal = repair.status === 'COMPLETED' || repair.status === 'CANCELLED';
+
+  return (
+    <div className="space-y-5">
+      <div className="flex flex-wrap items-start justify-between gap-3">
+        <div className="flex items-center gap-3">
+          <Button
+            variant="ghost"
+            size="icon"
+            onClick={() => navigate('/repairs')}
+            aria-label="Back"
+          >
+            <ArrowLeft className="h-4 w-4" />
+          </Button>
+          <div>
+            <div className="flex flex-wrap items-center gap-2">
+              <span className="text-xs uppercase tracking-wide text-muted-foreground">
+                Asset
+              </span>
+              <span className="font-mono text-2xl font-semibold tracking-tight text-foreground">
+                {repair.host.assetId}
+              </span>
+              <RepairStatusBadge status={repair.status} />
+            </div>
+            <div className="mt-0.5 flex items-center gap-1 text-xs text-muted-foreground">
+              <Server className="h-3 w-3" />
+              <span>{repair.host.name}</span>
+              {repair.host.location && <span>· {repair.host.location}</span>}
+            </div>
+          </div>
+        </div>
+
+        <div className="flex items-center gap-2">
+          <Select
+            value={repair.status}
+            onValueChange={(v) => statusMutation.mutate(v as RepairStatus)}
+            disabled={statusMutation.isPending}
+          >
+            <SelectTrigger className="w-40">
+              <SelectValue />
+            </SelectTrigger>
+            <SelectContent>
+              {repairStatusOptions.map((o) => (
+                <SelectItem key={o.value} value={o.value}>
+                  {o.label}
+                </SelectItem>
+              ))}
+            </SelectContent>
+          </Select>
+        </div>
+      </div>
+
+      <div className="grid gap-4 md:grid-cols-[1.3fr_1fr]">
+        <div className="space-y-4">
+          <ProblemCard repair={repair} onSaved={invalidate} disabled={terminal} />
+          <ProblemPartsCard repair={repair} onSaved={invalidate} disabled={terminal} />
+        </div>
+
+        <Card>
+          <CardHeader>
+            <CardTitle className="text-base">Comments</CardTitle>
+            <CardDescription>
+              Discuss progress, record findings, tag handoffs.
+            </CardDescription>
+          </CardHeader>
+          <CardContent>
+            <RepairCommentThread repairId={repair.id} />
+          </CardContent>
+        </Card>
+      </div>
+
+      <Card>
+        <CardHeader>
+          <CardTitle className="text-base">Timeline</CardTitle>
+        </CardHeader>
+        <CardContent>
+          <dl className="grid grid-cols-2 gap-2 text-sm md:grid-cols-4">
+            <Field label="Opened" value={new Date(repair.openedAt).toLocaleString()} />
+            <Field
+              label="Closed"
+              value={
+                repair.closedAt ? new Date(repair.closedAt).toLocaleString() : '—'
+              }
+            />
+            <Field
+              label="Assignee"
+              value={repair.assignee?.username ?? '—'}
+            />
+            <Field label="Updated" value={new Date(repair.updatedAt).toLocaleString()} />
+          </dl>
+          {repair.notes && (
+            <>
+              <Separator className="my-3" />
+              <div>
+                <p className="mb-1 text-xs font-medium text-muted-foreground">Notes</p>
+                <p className="whitespace-pre-wrap text-sm text-foreground">{repair.notes}</p>
+              </div>
+            </>
+          )}
+        </CardContent>
+      </Card>
+    </div>
+  );
+}
+
+function Field({ label, value }: { label: string; value: React.ReactNode }) {
+  return (
+    <div className="space-y-0.5">
+      <dt className="text-xs text-muted-foreground">{label}</dt>
+      <dd className="text-sm text-foreground">{value}</dd>
+    </div>
+  );
+}
+
+function ProblemCard({
+  repair,
+  onSaved,
+  disabled,
+}: {
+  repair: { id: string; problem: string };
+  onSaved: () => void;
+  disabled: boolean;
+}) {
+  const [editing, setEditing] = useState(false);
+  const [value, setValue] = useState(repair.problem);
+
+  useEffect(() => {
+    setValue(repair.problem);
+  }, [repair.problem]);
+
+  const mutation = useMutation({
+    mutationFn: (problem: string) => updateRepair(repair.id, { problem }),
+    onSuccess: () => {
+      toast.success('Problem updated');
+      setEditing(false);
+      onSaved();
+    },
+    onError: (err) =>
+      toast.error(err instanceof ApiRequestError ? err.body.message : 'Update failed'),
+  });
+
+  return (
+    <Card>
+      <CardHeader className="flex flex-row items-center justify-between space-y-0">
+        <CardTitle className="text-base">Problem</CardTitle>
+        {!editing && !disabled && (
+          <Button variant="ghost" size="sm" onClick={() => setEditing(true)}>
+            <Pencil className="h-3.5 w-3.5" />
+            Edit
+          </Button>
+        )}
+      </CardHeader>
+      <CardContent>
+        {editing ? (
+          <div className="space-y-2">
+            <Textarea
+              rows={4}
+              value={value}
+              onChange={(e) => setValue(e.target.value)}
+              disabled={mutation.isPending}
+            />
+            <div className="flex justify-end gap-2">
+              <Button
+                variant="outline"
+                size="sm"
+                onClick={() => {
+                  setValue(repair.problem);
+                  setEditing(false);
+                }}
+                disabled={mutation.isPending}
+              >
+                <X className="h-3.5 w-3.5" />
+                Cancel
+              </Button>
+              <Button
+                size="sm"
+                onClick={() => mutation.mutate(value.trim())}
+                disabled={
+                  mutation.isPending ||
+                  value.trim().length === 0 ||
+                  value.trim() === repair.problem
+                }
+              >
+                {mutation.isPending ? (
+                  <Loader2 className="h-3.5 w-3.5 animate-spin" />
+                ) : (
+                  <Check className="h-3.5 w-3.5" />
+                )}
+                Save
+              </Button>
+            </div>
+          </div>
+        ) : (
+          <p className="whitespace-pre-wrap text-sm text-foreground">{repair.problem}</p>
+        )}
+      </CardContent>
+    </Card>
+  );
+}
+
+function ProblemPartsCard({
+  repair,
+  onSaved,
+  disabled,
+}: {
+  repair: RepairJob;
+  onSaved: () => void;
+  disabled: boolean;
+}) {
+  const [picking, setPicking] = useState(false);
+  const [draft, setDraft] = useState<string[]>([]);
+
+  const deployedQuery = useQuery({
+    queryKey: queryKeys.hosts.deployedParts(repair.hostId),
+    queryFn: () => listHostDeployedParts(repair.hostId),
+    enabled: picking,
+  });
+
+  useEffect(() => {
+    if (picking) {
+      setDraft(repair.problemParts.map((pp) => pp.partId));
+    }
+  }, [picking, repair.problemParts]);
+
+  const mutation = useMutation({
+    mutationFn: (problemPartIds: string[]) =>
+      updateRepair(repair.id, { problemPartIds }),
+    onSuccess: () => {
+      toast.success('Problem parts updated');
+      setPicking(false);
+      onSaved();
+    },
+    onError: (err) =>
+      toast.error(err instanceof ApiRequestError ? err.body.message : 'Update failed'),
+  });
+
+  const removeMutation = useMutation({
+    mutationFn: (partId: string) => {
+      const next = repair.problemParts.map((pp) => pp.partId).filter((pid) => pid !== partId);
+      return updateRepair(repair.id, { problemPartIds: next });
+    },
+    onSuccess: () => {
+      toast.success('Part removed');
+      onSaved();
+    },
+    onError: (err) =>
+      toast.error(err instanceof ApiRequestError ? err.body.message : 'Remove failed'),
+  });
+
+  function toggle(partId: string, checked: boolean) {
+    setDraft((prev) =>
+      checked ? [...new Set([...prev, partId])] : prev.filter((id) => id !== partId),
+    );
+  }
+
+  return (
+    <Card>
+      <CardHeader className="flex flex-row items-center justify-between space-y-0">
+        <div>
+          <CardTitle className="text-base">Problem parts</CardTitle>
+          <CardDescription>
+            Deployed parts on this host involved in the issue.
+          </CardDescription>
+        </div>
+        {!picking && !disabled && (
+          <Button variant="outline" size="sm" onClick={() => setPicking(true)}>
+            <Plus className="h-3.5 w-3.5" />
+            Manage
+          </Button>
+        )}
+      </CardHeader>
+      <CardContent>
+        {picking ? (
+          <div className="space-y-3">
+            <div className="max-h-60 overflow-y-auto rounded-md border border-border">
+              {deployedQuery.isPending ? (
+                <Skeleton className="m-2 h-12" />
+              ) : !deployedQuery.data || deployedQuery.data.length === 0 ? (
+                <p className="p-3 text-xs text-muted-foreground">
+                  No deployed parts on this host.
+                </p>
+              ) : (
+                <ul className="divide-y divide-border">
+                  {deployedQuery.data.map((part) => {
+                    const checked = draft.includes(part.id);
+                    return (
+                      <li
+                        key={part.id}
+                        className="flex items-center gap-2 px-3 py-2 text-sm"
+                      >
+                        <Checkbox
+                          id={`rd-pp-${part.id}`}
+                          checked={checked}
+                          onCheckedChange={(v) => toggle(part.id, v === true)}
+                        />
+                        <label
+                          htmlFor={`rd-pp-${part.id}`}
+                          className="flex-1 cursor-pointer select-none"
+                        >
+                          <span className="font-mono text-xs">{part.serialNumber}</span>{' '}
+                          <span className="text-xs text-muted-foreground">
+                            {part.partModel.mpn}
+                          </span>
+                        </label>
+                      </li>
+                    );
+                  })}
+                </ul>
+              )}
+            </div>
+            <div className="flex justify-end gap-2">
+              <Button
+                variant="outline"
+                size="sm"
+                onClick={() => setPicking(false)}
+                disabled={mutation.isPending}
+              >
+                <X className="h-3.5 w-3.5" />
+                Cancel
+              </Button>
+              <Button
+                size="sm"
+                onClick={() => mutation.mutate(draft)}
+                disabled={mutation.isPending}
+              >
+                {mutation.isPending ? (
+                  <Loader2 className="h-3.5 w-3.5 animate-spin" />
+                ) : (
+                  <Check className="h-3.5 w-3.5" />
+                )}
+                Save
+              </Button>
+            </div>
+          </div>
+        ) : repair.problemParts.length === 0 ? (
+          <p className="text-sm text-muted-foreground">
+            No specific parts tagged — the repair is against the host itself.
+          </p>
+        ) : (
+          <ul className="divide-y divide-border rounded-md border border-border">
+            {repair.problemParts.map((pp) => (
+              <li
+                key={pp.partId}
+                className="flex items-center justify-between gap-3 px-3 py-2"
+              >
+                <div className="min-w-0 flex-1">
+                  <Link
+                    to={`/parts/${pp.part.id}`}
+                    className="font-mono text-xs font-medium text-foreground hover:underline"
+                  >
+                    {pp.part.serialNumber}
+                  </Link>
+                  <div className="flex items-center gap-2 text-xs text-muted-foreground">
+                    <span>{pp.part.partModel.mpn}</span>
+                    <PartStateBadge state={pp.part.state} />
+                  </div>
+                </div>
+                {!disabled && (
+                  <Button
+                    variant="ghost"
+                    size="icon"
+                    className="h-7 w-7 text-destructive hover:text-destructive"
+                    onClick={() => removeMutation.mutate(pp.partId)}
+                    disabled={removeMutation.isPending}
+                    aria-label="Remove part"
+                  >
+                    <Trash2 className="h-3.5 w-3.5" />
+                  </Button>
+                )}
+              </li>
+            ))}
+          </ul>
+        )}
+      </CardContent>
+    </Card>
+  );
+}
diff --git a/apps/web/src/pages/Repairs.tsx b/apps/web/src/pages/Repairs.tsx
index cded6d8..3b00454 100644
--- a/apps/web/src/pages/Repairs.tsx
+++ b/apps/web/src/pages/Repairs.tsx
@@ -1,17 +1,16 @@
 import { useMemo, useState } from 'react';
-import { Link } from 'react-router-dom';
+import { Link, useNavigate } from 'react-router-dom';
 import type { ColumnDef } from '@tanstack/react-table';
 import { useMutation, useQueryClient } from '@tanstack/react-query';
 import { parseAsString } from 'nuqs';
 import { toast } from 'sonner';
-import { Edit, MoreHorizontal, Plus, Trash2, Wrench } from 'lucide-react';
+import { MoreHorizontal, Plus, Trash2, Wrench } from 'lucide-react';
 import type { RepairStatus } from '@vector/shared';
 import {
   Button,
   DropdownMenu,
   DropdownMenuContent,
   DropdownMenuItem,
-  DropdownMenuSeparator,
   DropdownMenuTrigger,
   Select,
   SelectContent,
@@ -44,8 +43,8 @@ const ALL = '__all__';
 
 export default function Repairs() {
   const queryClient = useQueryClient();
+  const navigate = useNavigate();
   const [createOpen, setCreateOpen] = useState(false);
-  const [editing, setEditing] = useState<RepairJob | null>(null);
   const [deleting, setDeleting] = useState<RepairJob | null>(null);
 
   const deleteMutation = useMutation({
@@ -67,31 +66,34 @@ export default function Repairs() {
         cell: ({ row }) => <RepairStatusBadge status={row.original.status} />,
       },
       {
-        id: 'part',
-        header: 'Part',
+        id: 'assetId',
+        header: 'Asset ID',
         cell: ({ row }) => (
           <Link
-            to={`/parts/${row.original.partId}`}
-            className="font-medium text-foreground hover:underline"
+            to={`/repairs/${row.original.id}`}
+            className="font-mono text-xs font-medium text-foreground hover:underline"
           >
-            {row.original.part.serialNumber}
+            {row.original.host.assetId}
           </Link>
         ),
       },
-      {
-        id: 'mpn',
-        header: 'MPN',
-        cell: ({ row }) => (
-          <span className="text-sm text-muted-foreground">{row.original.part.mpn}</span>
-        ),
-      },
       {
         id: 'host',
         header: 'Host',
         cell: ({ row }) => (
-          <span className="text-sm text-muted-foreground">
-            {row.original.host?.name ?? '—'}
-          </span>
+          <span className="text-sm">{row.original.host.name}</span>
+        ),
+      },
+      {
+        id: 'problem',
+        header: 'Problem',
+        cell: ({ row }) => (
+          <Link
+            to={`/repairs/${row.original.id}`}
+            className="line-clamp-1 max-w-sm text-sm text-foreground hover:underline"
+          >
+            {row.original.problem}
+          </Link>
         ),
       },
       {
@@ -126,11 +128,6 @@ export default function Repairs() {
               </Button>
             </DropdownMenuTrigger>
             <DropdownMenuContent align="end" className="w-36">
-              <DropdownMenuItem onSelect={() => setEditing(row.original)}>
-                <Edit className="h-3.5 w-3.5" />
-                Edit
-              </DropdownMenuItem>
-              <DropdownMenuSeparator />
               <DropdownMenuItem
                 onSelect={() => setDeleting(row.original)}
                 className="text-destructive focus:text-destructive"
@@ -150,7 +147,7 @@ export default function Repairs() {
     <div className="space-y-5">
       <PageHeader
         title="Repairs"
-        description="Open RMAs and host-attached repair jobs."
+        description="Open work against hosts. Click a row to view and comment."
         actions={
           <Button onClick={() => setCreateOpen(true)}>
             <Plus className="h-4 w-4" />
@@ -204,11 +201,10 @@ export default function Repairs() {
         }
       />
 
-      <RepairFormDialog open={createOpen} onOpenChange={setCreateOpen} />
       <RepairFormDialog
-        open={Boolean(editing)}
-        onOpenChange={(o) => !o && setEditing(null)}
-        repair={editing}
+        open={createOpen}
+        onOpenChange={setCreateOpen}
+        onCreated={(repair) => navigate(`/repairs/${repair.id}`)}
       />
       <ConfirmDialog
         open={Boolean(deleting)}
@@ -216,7 +212,7 @@ export default function Repairs() {
         title="Delete repair?"
         description={
           deleting
-            ? `Remove repair for ${deleting.part.serialNumber}. This cannot be undone.`
+            ? `Remove repair "${deleting.problem.slice(0, 60)}" on ${deleting.host.name}. This cannot be undone.`
             : undefined
         }
         confirmLabel="Delete"
diff --git a/packages/db/prisma/migrations/20260417130319_mpn_catalog_and_host_repairs/migration.sql b/packages/db/prisma/migrations/20260417130319_mpn_catalog_and_host_repairs/migration.sql
new file mode 100644
index 0000000..94be029
--- /dev/null
+++ b/packages/db/prisma/migrations/20260417130319_mpn_catalog_and_host_repairs/migration.sql
@@ -0,0 +1,204 @@
+-- Domain rework: EOL moves from Manufacturer to a new PartModel catalog (keyed by manufacturerId+mpn);
+-- repairs move from Part-scoped to Host-scoped with an optional problem-parts join; Host gains a
+-- required+unique assetId; RepairJob gains a `problem` field and loses its direct `partId` FK.
+--
+-- Data-preserving reshape for SQLite. Steps:
+--   1. Create new catalog + join + comment tables.
+--   2. Seed PartModel from DISTINCT (manufacturerId, mpn) on Part, carrying Manufacturer.eolDate forward.
+--   3. Snapshot existing RepairJob.partId into RepairJobPart so historic repairs still remember the part.
+--   4. Ensure every RepairJob has a hostId (synthesize "__Unassigned__" host if needed) before hostId NOT NULL.
+--   5. Rebuild Host (add assetId NOT NULL+unique, backfilled with "H-<short>"), Manufacturer (drop eolDate),
+--      Part (add partModelId via lookup + hostId nullable, drop mpn + replacementPartId), and RepairJob
+--      (drop partId, add problem with COALESCE(notes, fallback), hostId NOT NULL).
+
+-- CreateTable: PartModel catalog
+CREATE TABLE "PartModel" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "manufacturerId" TEXT NOT NULL,
+    "mpn" TEXT NOT NULL,
+    "eolDate" DATETIME,
+    "notes" TEXT,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" DATETIME NOT NULL,
+    CONSTRAINT "PartModel_manufacturerId_fkey" FOREIGN KEY ("manufacturerId") REFERENCES "Manufacturer" ("id") ON DELETE RESTRICT ON UPDATE CASCADE
+);
+
+-- Backfill PartModel from DISTINCT (manufacturerId, mpn) on existing Part rows, carrying the
+-- current Manufacturer.eolDate into the new per-MPN eolDate. Admins re-tune per MPN afterward.
+INSERT INTO "PartModel" ("id", "manufacturerId", "mpn", "eolDate", "createdAt", "updatedAt")
+SELECT
+    lower(hex(randomblob(16))),
+    d."manufacturerId",
+    d."mpn",
+    m."eolDate",
+    CURRENT_TIMESTAMP,
+    CURRENT_TIMESTAMP
+FROM (SELECT DISTINCT "manufacturerId", "mpn" FROM "Part") d
+LEFT JOIN "Manufacturer" m ON m."id" = d."manufacturerId";
+
+-- CreateTable: RepairJobPart join
+CREATE TABLE "RepairJobPart" (
+    "repairJobId" TEXT NOT NULL,
+    "partId" TEXT NOT NULL,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY ("repairJobId", "partId"),
+    CONSTRAINT "RepairJobPart_repairJobId_fkey" FOREIGN KEY ("repairJobId") REFERENCES "RepairJob" ("id") ON DELETE CASCADE ON UPDATE CASCADE,
+    CONSTRAINT "RepairJobPart_partId_fkey" FOREIGN KEY ("partId") REFERENCES "Part" ("id") ON DELETE RESTRICT ON UPDATE CASCADE
+);
+
+-- Snapshot old single-part repairs into the new join table so each historic repair still points at
+-- its original problem part.
+INSERT INTO "RepairJobPart" ("repairJobId", "partId", "createdAt")
+SELECT "id", "partId", CURRENT_TIMESTAMP FROM "RepairJob";
+
+-- CreateTable: RepairComment
+CREATE TABLE "RepairComment" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "repairJobId" TEXT NOT NULL,
+    "userId" TEXT,
+    "content" TEXT NOT NULL,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    CONSTRAINT "RepairComment_repairJobId_fkey" FOREIGN KEY ("repairJobId") REFERENCES "RepairJob" ("id") ON DELETE CASCADE ON UPDATE CASCADE,
+    CONSTRAINT "RepairComment_userId_fkey" FOREIGN KEY ("userId") REFERENCES "User" ("id") ON DELETE SET NULL ON UPDATE CASCADE
+);
+
+-- Ensure every RepairJob has a hostId before we tighten the column to NOT NULL. Repairs with a
+-- NULL hostId get attached to a synthetic "__Unassigned__" host so no rows are lost; admins can
+-- reassign them afterward.
+INSERT INTO "Host" ("id", "name", "createdAt", "updatedAt")
+SELECT lower(hex(randomblob(16))), '__Unassigned__', CURRENT_TIMESTAMP, CURRENT_TIMESTAMP
+WHERE EXISTS (SELECT 1 FROM "RepairJob" WHERE "hostId" IS NULL)
+  AND NOT EXISTS (SELECT 1 FROM "Host" WHERE "name" = '__Unassigned__');
+
+UPDATE "RepairJob"
+SET "hostId" = (SELECT "id" FROM "Host" WHERE "name" = '__Unassigned__')
+WHERE "hostId" IS NULL;
+
+-- RedefineTables: destructive reshape of Host / Manufacturer / Part / RepairJob.
+PRAGMA defer_foreign_keys=ON;
+PRAGMA foreign_keys=OFF;
+
+-- Host: add assetId NOT NULL + unique, backfilled with "H-<first-8-chars-of-id>" so existing rows
+-- carry a deterministic placeholder admins can rename.
+CREATE TABLE "new_Host" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "assetId" TEXT NOT NULL,
+    "name" TEXT NOT NULL,
+    "location" TEXT,
+    "notes" TEXT,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" DATETIME NOT NULL
+);
+INSERT INTO "new_Host" ("id", "assetId", "name", "location", "notes", "createdAt", "updatedAt")
+SELECT "id", 'H-' || substr("id", 1, 8), "name", "location", "notes", "createdAt", "updatedAt"
+FROM "Host";
+DROP TABLE "Host";
+ALTER TABLE "new_Host" RENAME TO "Host";
+CREATE UNIQUE INDEX "Host_assetId_key" ON "Host"("assetId");
+CREATE UNIQUE INDEX "Host_name_key" ON "Host"("name");
+
+-- Manufacturer: drop eolDate (EOL now lives on PartModel).
+CREATE TABLE "new_Manufacturer" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "name" TEXT NOT NULL,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" DATETIME NOT NULL
+);
+INSERT INTO "new_Manufacturer" ("id", "name", "createdAt", "updatedAt")
+SELECT "id", "name", "createdAt", "updatedAt" FROM "Manufacturer";
+DROP TABLE "Manufacturer";
+ALTER TABLE "new_Manufacturer" RENAME TO "Manufacturer";
+CREATE UNIQUE INDEX "Manufacturer_name_key" ON "Manufacturer"("name");
+
+-- Part: add partModelId (looked up via the backfilled PartModel rows), add hostId (nullable;
+-- admins populate when deploying parts). Drop the free-text mpn column and the unused
+-- replacementPartId self-relation.
+CREATE TABLE "new_Part" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "serialNumber" TEXT NOT NULL,
+    "partModelId" TEXT NOT NULL,
+    "manufacturerId" TEXT NOT NULL,
+    "price" REAL,
+    "state" TEXT NOT NULL DEFAULT 'SPARE',
+    "binId" TEXT,
+    "categoryId" TEXT,
+    "hostId" TEXT,
+    "notes" TEXT,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" DATETIME NOT NULL,
+    CONSTRAINT "Part_partModelId_fkey" FOREIGN KEY ("partModelId") REFERENCES "PartModel" ("id") ON DELETE RESTRICT ON UPDATE CASCADE,
+    CONSTRAINT "Part_manufacturerId_fkey" FOREIGN KEY ("manufacturerId") REFERENCES "Manufacturer" ("id") ON DELETE RESTRICT ON UPDATE CASCADE,
+    CONSTRAINT "Part_binId_fkey" FOREIGN KEY ("binId") REFERENCES "Bin" ("id") ON DELETE SET NULL ON UPDATE CASCADE,
+    CONSTRAINT "Part_categoryId_fkey" FOREIGN KEY ("categoryId") REFERENCES "Category" ("id") ON DELETE SET NULL ON UPDATE CASCADE,
+    CONSTRAINT "Part_hostId_fkey" FOREIGN KEY ("hostId") REFERENCES "Host" ("id") ON DELETE SET NULL ON UPDATE CASCADE
+);
+INSERT INTO "new_Part" ("id", "serialNumber", "partModelId", "manufacturerId", "price", "state", "binId", "categoryId", "hostId", "notes", "createdAt", "updatedAt")
+SELECT
+    p."id",
+    p."serialNumber",
+    (SELECT pm."id" FROM "PartModel" pm WHERE pm."manufacturerId" = p."manufacturerId" AND pm."mpn" = p."mpn" LIMIT 1),
+    p."manufacturerId",
+    p."price",
+    p."state",
+    p."binId",
+    p."categoryId",
+    NULL,
+    p."notes",
+    p."createdAt",
+    p."updatedAt"
+FROM "Part" p;
+DROP TABLE "Part";
+ALTER TABLE "new_Part" RENAME TO "Part";
+CREATE UNIQUE INDEX "Part_serialNumber_key" ON "Part"("serialNumber");
+CREATE INDEX "Part_state_idx" ON "Part"("state");
+CREATE INDEX "Part_binId_idx" ON "Part"("binId");
+CREATE INDEX "Part_manufacturerId_idx" ON "Part"("manufacturerId");
+CREATE INDEX "Part_partModelId_idx" ON "Part"("partModelId");
+CREATE INDEX "Part_categoryId_idx" ON "Part"("categoryId");
+CREATE INDEX "Part_hostId_idx" ON "Part"("hostId");
+
+-- RepairJob: drop partId (problem part now lives in RepairJobPart), require hostId, add problem
+-- (carried over from notes as a best-effort fallback for historical rows).
+CREATE TABLE "new_RepairJob" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "hostId" TEXT NOT NULL,
+    "assigneeId" TEXT,
+    "status" TEXT NOT NULL DEFAULT 'PENDING',
+    "problem" TEXT NOT NULL,
+    "openedAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "closedAt" DATETIME,
+    "notes" TEXT,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" DATETIME NOT NULL,
+    CONSTRAINT "RepairJob_hostId_fkey" FOREIGN KEY ("hostId") REFERENCES "Host" ("id") ON DELETE RESTRICT ON UPDATE CASCADE,
+    CONSTRAINT "RepairJob_assigneeId_fkey" FOREIGN KEY ("assigneeId") REFERENCES "User" ("id") ON DELETE SET NULL ON UPDATE CASCADE
+);
+INSERT INTO "new_RepairJob" ("id", "hostId", "assigneeId", "status", "problem", "openedAt", "closedAt", "notes", "createdAt", "updatedAt")
+SELECT
+    r."id",
+    r."hostId",
+    r."assigneeId",
+    r."status",
+    COALESCE(r."notes", 'Imported repair — problem not recorded'),
+    r."openedAt",
+    r."closedAt",
+    r."notes",
+    r."createdAt",
+    r."updatedAt"
+FROM "RepairJob" r;
+DROP TABLE "RepairJob";
+ALTER TABLE "new_RepairJob" RENAME TO "RepairJob";
+CREATE INDEX "RepairJob_status_idx" ON "RepairJob"("status");
+CREATE INDEX "RepairJob_hostId_idx" ON "RepairJob"("hostId");
+CREATE INDEX "RepairJob_assigneeId_idx" ON "RepairJob"("assigneeId");
+CREATE INDEX "RepairJob_status_openedAt_idx" ON "RepairJob"("status", "openedAt" DESC);
+
+PRAGMA foreign_keys=ON;
+PRAGMA defer_foreign_keys=OFF;
+
+-- Indexes for the new catalog + join + comment tables.
+CREATE INDEX "PartModel_manufacturerId_idx" ON "PartModel"("manufacturerId");
+CREATE INDEX "PartModel_eolDate_idx" ON "PartModel"("eolDate");
+CREATE UNIQUE INDEX "PartModel_manufacturerId_mpn_key" ON "PartModel"("manufacturerId", "mpn");
+CREATE INDEX "RepairJobPart_partId_idx" ON "RepairJobPart"("partId");
+CREATE INDEX "RepairComment_repairJobId_createdAt_idx" ON "RepairComment"("repairJobId", "createdAt");
diff --git a/packages/db/prisma/schema.prisma b/packages/db/prisma/schema.prisma
index 4655a36..3d66e74 100644
--- a/packages/db/prisma/schema.prisma
+++ b/packages/db/prisma/schema.prisma
@@ -16,16 +16,17 @@ datasource db {
 }
 
 model User {
-  id                String         @id @default(uuid())
-  username          String         @unique
-  email             String         @unique
+  id                String          @id @default(uuid())
+  username          String          @unique
+  email             String          @unique
   passwordHash      String
-  role              String         @default("TECHNICIAN")
-  createdAt         DateTime       @default(now())
-  updatedAt         DateTime       @updatedAt
+  role              String          @default("TECHNICIAN")
+  createdAt         DateTime        @default(now())
+  updatedAt         DateTime        @updatedAt
   partEvents        PartEvent[]
   refreshTokens     RefreshToken[]
-  repairAssignments RepairJob[]    @relation("RepairAssignee")
+  repairAssignments RepairJob[]     @relation("RepairAssignee")
+  repairComments    RepairComment[]
   savedViews        SavedView[]
   csvImportJobs     CsvImportJob[]
 }
@@ -45,12 +46,28 @@ model RefreshToken {
 }
 
 model Manufacturer {
-  id        String    @id @default(uuid())
-  name      String    @unique
-  eolDate   DateTime?
-  createdAt DateTime  @default(now())
-  updatedAt DateTime  @updatedAt
-  parts     Part[]
+  id         String      @id @default(uuid())
+  name       String      @unique
+  createdAt  DateTime    @default(now())
+  updatedAt  DateTime    @updatedAt
+  parts      Part[]
+  partModels PartModel[]
+}
+
+model PartModel {
+  id             String       @id @default(uuid())
+  manufacturerId String
+  manufacturer   Manufacturer @relation(fields: [manufacturerId], references: [id], onDelete: Restrict)
+  mpn            String
+  eolDate        DateTime?
+  notes          String?
+  createdAt      DateTime     @default(now())
+  updatedAt      DateTime     @updatedAt
+  parts          Part[]
+
+  @@unique([manufacturerId, mpn])
+  @@index([manufacturerId])
+  @@index([eolDate])
 }
 
 model Site {
@@ -97,33 +114,33 @@ model Category {
 }
 
 model Part {
-  id                String       @id @default(uuid())
-  serialNumber      String       @unique
-  mpn               String
-  manufacturerId    String
-  manufacturer      Manufacturer @relation(fields: [manufacturerId], references: [id], onDelete: Restrict)
-  price             Float?
-  state             String       @default("SPARE")
-  binId             String?
-  bin               Bin?         @relation(fields: [binId], references: [id], onDelete: SetNull)
-  categoryId        String?
-  category          Category?    @relation(fields: [categoryId], references: [id], onDelete: SetNull)
-  replacementPartId String?
-  replacement       Part?        @relation("PartReplacement", fields: [replacementPartId], references: [id], onDelete: SetNull)
-  replacedBy        Part[]       @relation("PartReplacement")
-  notes             String?
-  createdAt         DateTime     @default(now())
-  updatedAt         DateTime     @updatedAt
-  events            PartEvent[]
-  tags              PartTag[]
-  repairs           RepairJob[]
+  id             String          @id @default(uuid())
+  serialNumber   String          @unique
+  partModelId    String
+  partModel      PartModel       @relation(fields: [partModelId], references: [id], onDelete: Restrict)
+  manufacturerId String
+  manufacturer   Manufacturer    @relation(fields: [manufacturerId], references: [id], onDelete: Restrict)
+  price          Float?
+  state          String          @default("SPARE")
+  binId          String?
+  bin            Bin?            @relation(fields: [binId], references: [id], onDelete: SetNull)
+  categoryId     String?
+  category       Category?       @relation(fields: [categoryId], references: [id], onDelete: SetNull)
+  hostId         String?
+  host           Host?           @relation(fields: [hostId], references: [id], onDelete: SetNull)
+  notes          String?
+  createdAt      DateTime        @default(now())
+  updatedAt      DateTime        @updatedAt
+  events         PartEvent[]
+  tags           PartTag[]
+  problemInRepairs RepairJobPart[]
 
   @@index([state])
   @@index([binId])
   @@index([manufacturerId])
-  @@index([mpn])
+  @@index([partModelId])
   @@index([categoryId])
-  @@index([replacementPartId])
+  @@index([hostId])
 }
 
 model PartEvent {
@@ -164,36 +181,61 @@ model PartTag {
 
 model Host {
   id        String      @id @default(uuid())
+  assetId   String      @unique
   name      String      @unique
   location  String?
   notes     String?
   createdAt DateTime    @default(now())
   updatedAt DateTime    @updatedAt
+  parts     Part[]
   repairs   RepairJob[]
 }
 
 model RepairJob {
-  id         String    @id @default(uuid())
-  partId     String
-  part       Part      @relation(fields: [partId], references: [id], onDelete: Cascade)
-  hostId     String?
-  host       Host?     @relation(fields: [hostId], references: [id], onDelete: SetNull)
-  assigneeId String?
-  assignee   User?     @relation("RepairAssignee", fields: [assigneeId], references: [id], onDelete: SetNull)
-  status     String    @default("PENDING")
-  openedAt   DateTime  @default(now())
-  closedAt   DateTime?
-  notes      String?
-  createdAt  DateTime  @default(now())
-  updatedAt  DateTime  @updatedAt
+  id           String          @id @default(uuid())
+  hostId       String
+  host         Host            @relation(fields: [hostId], references: [id], onDelete: Restrict)
+  assigneeId   String?
+  assignee     User?           @relation("RepairAssignee", fields: [assigneeId], references: [id], onDelete: SetNull)
+  status       String          @default("PENDING")
+  problem      String
+  openedAt     DateTime        @default(now())
+  closedAt     DateTime?
+  notes        String?
+  createdAt    DateTime        @default(now())
+  updatedAt    DateTime        @updatedAt
+  problemParts RepairJobPart[]
+  comments     RepairComment[]
 
-  @@index([partId])
   @@index([status])
   @@index([hostId])
   @@index([assigneeId])
   @@index([status, openedAt(sort: Desc)])
 }
 
+model RepairJobPart {
+  repairJobId String
+  partId      String
+  repairJob   RepairJob @relation(fields: [repairJobId], references: [id], onDelete: Cascade)
+  part        Part      @relation(fields: [partId], references: [id], onDelete: Restrict)
+  createdAt   DateTime  @default(now())
+
+  @@id([repairJobId, partId])
+  @@index([partId])
+}
+
+model RepairComment {
+  id          String    @id @default(uuid())
+  repairJobId String
+  repairJob   RepairJob @relation(fields: [repairJobId], references: [id], onDelete: Cascade)
+  userId      String?
+  user        User?     @relation(fields: [userId], references: [id], onDelete: SetNull)
+  content     String
+  createdAt   DateTime  @default(now())
+
+  @@index([repairJobId, createdAt])
+}
+
 model WebhookSubscription {
   id        String   @id @default(uuid())
   url       String
diff --git a/packages/shared/src/analytics.ts b/packages/shared/src/analytics.ts
index 53db67f..4c5cad2 100644
--- a/packages/shared/src/analytics.ts
+++ b/packages/shared/src/analytics.ts
@@ -18,10 +18,12 @@ export interface BinCount {
   count: number;
 }
 
-export interface ManufacturerEolSummary {
+export interface PartModelEolSummary {
+  partModelId: string;
+  mpn: string;
   manufacturerId: string;
-  name: string;
-  eolDate: string | null;
+  manufacturerName: string;
+  eolDate: string;
   deployedCount: number;
 }
 
@@ -30,6 +32,6 @@ export interface DashboardAnalytics {
   byState: StateCount[];
   ageBuckets: AgeBucket[];
   topBins: BinCount[];
-  deployedPastEol: ManufacturerEolSummary[];
+  deployedPastEol: PartModelEolSummary[];
   openRepairs: number;
 }
diff --git a/packages/shared/src/enums.ts b/packages/shared/src/enums.ts
index 4484c95..1699906 100644
--- a/packages/shared/src/enums.ts
+++ b/packages/shared/src/enums.ts
@@ -13,6 +13,8 @@ export const PartEventType = z.enum([
   'FIELD_UPDATED',
   'REPAIR_STARTED',
   'REPAIR_COMPLETED',
+  'REPAIR_CANCELLED',
+  'REPAIR_COMMENTED',
   'TAG_ADDED',
   'TAG_REMOVED',
 ]);
diff --git a/packages/shared/src/hosts.ts b/packages/shared/src/hosts.ts
index 68d5d44..9fda8e2 100644
--- a/packages/shared/src/hosts.ts
+++ b/packages/shared/src/hosts.ts
@@ -1,7 +1,14 @@
 import { z } from 'zod';
 import { PaginationQuery } from './pagination.js';
 
+const AssetId = z
+  .string()
+  .trim()
+  .min(1, 'Asset ID is required')
+  .max(64, 'Asset ID must be 64 characters or fewer');
+
 export const CreateHostRequest = z.object({
+  assetId: AssetId,
   name: z.string().min(1).max(128),
   location: z.string().max(256).optional().nullable(),
   notes: z.string().max(4096).optional().nullable(),
@@ -10,6 +17,7 @@ export type CreateHostRequest = z.infer<typeof CreateHostRequest>;
 
 export const UpdateHostRequest = z
   .object({
+    assetId: AssetId.optional(),
     name: z.string().min(1).max(128).optional(),
     location: z.string().max(256).nullable().optional(),
     notes: z.string().max(4096).nullable().optional(),
diff --git a/packages/shared/src/index.ts b/packages/shared/src/index.ts
index 9dc172a..6736f44 100644
--- a/packages/shared/src/index.ts
+++ b/packages/shared/src/index.ts
@@ -2,6 +2,7 @@ export * from './enums.js';
 export * from './auth.js';
 export * from './users.js';
 export * from './manufacturers.js';
+export * from './part-models.js';
 export * from './locations.js';
 export * from './parts.js';
 export * from './env.js';
diff --git a/packages/shared/src/manufacturers.ts b/packages/shared/src/manufacturers.ts
index 76859fc..94f4e58 100644
--- a/packages/shared/src/manufacturers.ts
+++ b/packages/shared/src/manufacturers.ts
@@ -1,19 +1,13 @@
 import { z } from 'zod';
 
-// ISO datetime string (e.g. "2027-12-31T00:00:00.000Z"). Clients may send date-only "2027-12-31";
-// API layer is expected to coerce to Date.
-const IsoDate = z.string().datetime({ offset: true }).or(z.string().regex(/^\d{4}-\d{2}-\d{2}$/));
-
 export const CreateManufacturerRequest = z.object({
   name: z.string().min(1).max(128),
-  eolDate: IsoDate.optional().nullable(),
 });
 export type CreateManufacturerRequest = z.infer<typeof CreateManufacturerRequest>;
 
 export const UpdateManufacturerRequest = z
   .object({
     name: z.string().min(1).max(128).optional(),
-    eolDate: IsoDate.nullable().optional(),
   })
   .refine((v) => Object.keys(v).length > 0, { message: 'At least one field required' });
 export type UpdateManufacturerRequest = z.infer<typeof UpdateManufacturerRequest>;
diff --git a/packages/shared/src/part-models.ts b/packages/shared/src/part-models.ts
new file mode 100644
index 0000000..e5e7da6
--- /dev/null
+++ b/packages/shared/src/part-models.ts
@@ -0,0 +1,29 @@
+import { z } from 'zod';
+import { PaginationQuery } from './pagination.js';
+
+const IsoDate = z.string().datetime({ offset: true }).or(z.string().regex(/^\d{4}-\d{2}-\d{2}$/));
+
+export const CreatePartModelRequest = z.object({
+  manufacturerId: z.string().uuid(),
+  mpn: z.string().min(1).max(128),
+  eolDate: IsoDate.nullable().optional(),
+  notes: z.string().max(4096).nullable().optional(),
+});
+export type CreatePartModelRequest = z.infer<typeof CreatePartModelRequest>;
+
+export const UpdatePartModelRequest = z
+  .object({
+    manufacturerId: z.string().uuid().optional(),
+    mpn: z.string().min(1).max(128).optional(),
+    eolDate: IsoDate.nullable().optional(),
+    notes: z.string().max(4096).nullable().optional(),
+  })
+  .refine((v) => Object.keys(v).length > 0, { message: 'At least one field required' });
+export type UpdatePartModelRequest = z.infer<typeof UpdatePartModelRequest>;
+
+export const PartModelListQuery = PaginationQuery.extend({
+  manufacturerId: z.string().uuid().optional(),
+  q: z.string().max(128).optional(),
+  eolBefore: IsoDate.optional(),
+});
+export type PartModelListQuery = z.infer<typeof PartModelListQuery>;
diff --git a/packages/shared/src/parts.test.ts b/packages/shared/src/parts.test.ts
index c39ae9b..a78f166 100644
--- a/packages/shared/src/parts.test.ts
+++ b/packages/shared/src/parts.test.ts
@@ -3,50 +3,54 @@ import { BulkPartsRequest, CreatePartRequest, PartListQuery, UpdatePartRequest }
 
 const mfgId = '11111111-1111-4111-8111-111111111111';
 const binId = '22222222-2222-4222-8222-222222222222';
+const modelId = '44444444-4444-4444-8444-444444444444';
 
 describe('CreatePartRequest', () => {
-  it('accepts a minimal valid payload', () => {
+  it('accepts a partModelId-based payload', () => {
     const r = CreatePartRequest.parse({
       serialNumber: 'SN-1',
-      mpn: 'MPN-1',
-      manufacturerId: mfgId,
+      partModelId: modelId,
     });
     expect(r.serialNumber).toBe('SN-1');
   });
 
-  it('rejects empty serial / mpn', () => {
+  it('accepts a manufacturerId + mpn payload (auto-upsert path)', () => {
+    const r = CreatePartRequest.parse({
+      serialNumber: 'SN-1',
+      manufacturerId: mfgId,
+      mpn: 'MPN-1',
+    });
+    expect(r.mpn).toBe('MPN-1');
+  });
+
+  it('rejects when neither partModelId nor (manufacturerId + mpn) is provided', () => {
     expect(
-      CreatePartRequest.safeParse({ serialNumber: '', mpn: 'X', manufacturerId: mfgId }).success,
+      CreatePartRequest.safeParse({ serialNumber: 'SN-1', manufacturerId: mfgId }).success,
     ).toBe(false);
+    expect(CreatePartRequest.safeParse({ serialNumber: 'SN-1' }).success).toBe(false);
+  });
+
+  it('rejects empty serial', () => {
     expect(
-      CreatePartRequest.safeParse({ serialNumber: 'X', mpn: '', manufacturerId: mfgId }).success,
+      CreatePartRequest.safeParse({ serialNumber: '', partModelId: modelId }).success,
     ).toBe(false);
   });
 
   it('rejects negative price', () => {
     const res = CreatePartRequest.safeParse({
       serialNumber: 'X',
-      mpn: 'Y',
-      manufacturerId: mfgId,
+      partModelId: modelId,
       price: -1,
     });
     expect(res.success).toBe(false);
   });
 
-  it('rejects non-uuid manufacturer id', () => {
-    expect(
-      CreatePartRequest.safeParse({ serialNumber: 'X', mpn: 'Y', manufacturerId: 'not-uuid' })
-        .success,
-    ).toBe(false);
-  });
-
   it('caps tagIds at 32', () => {
     const tagIds = Array.from({ length: 33 }, () => '33333333-3333-4333-8333-333333333333');
     expect(
       CreatePartRequest.safeParse({
         serialNumber: 'X',
-        mpn: 'Y',
-        manufacturerId: mfgId,
+        partModelId: modelId,
         tagIds,
       }).success,
     ).toBe(false);
@@ -66,6 +70,11 @@ describe('UpdatePartRequest', () => {
     const r = UpdatePartRequest.parse({ binId: null });
     expect(r.binId).toBeNull();
   });
+
+  it('permits nullable hostId to clear host assignment', () => {
+    const r = UpdatePartRequest.parse({ hostId: null });
+    expect(r.hostId).toBeNull();
+  });
 });
 
 describe('PartListQuery', () => {
@@ -106,6 +115,11 @@ describe('BulkPartsRequest', () => {
     expect(r.binId).toBeNull();
   });
 
+  it('accepts hostId=null to unassign', () => {
+    const r = BulkPartsRequest.parse({ ids: [mfgId], hostId: null });
+    expect(r.hostId).toBeNull();
+  });
+
   it('caps ids at 500', () => {
     const ids = Array.from({ length: 501 }, () => binId);
     expect(BulkPartsRequest.safeParse({ ids, state: 'SPARE' }).success).toBe(false);
diff --git a/packages/shared/src/parts.ts b/packages/shared/src/parts.ts
index 42d3e07..87fbf3d 100644
--- a/packages/shared/src/parts.ts
+++ b/packages/shared/src/parts.ts
@@ -2,31 +2,59 @@ import { z } from 'zod';
 import { PartState } from './enums.js';
 import { PaginationQuery } from './pagination.js';
 
-export const CreatePartRequest = z.object({
-  serialNumber: z.string().min(1).max(128),
-  mpn: z.string().min(1).max(128),
-  manufacturerId: z.string().uuid(),
-  price: z.number().nonnegative().optional().nullable(),
-  state: PartState.optional(),
-  binId: z.string().uuid().optional().nullable(),
-  notes: z.string().max(4096).optional().nullable(),
-  categoryId: z.string().uuid().optional().nullable(),
-  replacementPartId: z.string().uuid().optional().nullable(),
-  tagIds: z.array(z.string().uuid()).max(32).optional(),
-});
+// A part create/update can either reference an existing PartModel directly (partModelId)
+// or auto-provision one via manufacturerId + mpn. Exactly one form is required on create.
+const modelSelector = z
+  .object({
+    partModelId: z.string().uuid().optional(),
+    manufacturerId: z.string().uuid().optional(),
+    mpn: z.string().min(1).max(128).optional(),
+  })
+  .refine(
+    (v) => v.partModelId !== undefined || (v.manufacturerId !== undefined && v.mpn !== undefined),
+    { message: 'Provide partModelId or both manufacturerId and mpn' },
+  );
+
+export const CreatePartRequest = z
+  .object({
+    serialNumber: z.string().min(1).max(128),
+    partModelId: z.string().uuid().optional(),
+    manufacturerId: z.string().uuid().optional(),
+    mpn: z.string().min(1).max(128).optional(),
+    price: z.number().nonnegative().optional().nullable(),
+    state: PartState.optional(),
+    binId: z.string().uuid().optional().nullable(),
+    hostId: z.string().uuid().optional().nullable(),
+    notes: z.string().max(4096).optional().nullable(),
+    categoryId: z.string().uuid().optional().nullable(),
+    tagIds: z.array(z.string().uuid()).max(32).optional(),
+  })
+  .superRefine((v, ctx) => {
+    const parsed = modelSelector.safeParse({
+      partModelId: v.partModelId,
+      manufacturerId: v.manufacturerId,
+      mpn: v.mpn,
+    });
+    if (!parsed.success) {
+      ctx.addIssue({
+        code: z.ZodIssueCode.custom,
+        message: 'Provide partModelId or both manufacturerId and mpn',
+        path: ['partModelId'],
+      });
+    }
+  });
 export type CreatePartRequest = z.infer<typeof CreatePartRequest>;
 
 export const UpdatePartRequest = z
   .object({
     serialNumber: z.string().min(1).max(128).optional(),
-    mpn: z.string().min(1).max(128).optional(),
-    manufacturerId: z.string().uuid().optional(),
+    partModelId: z.string().uuid().optional(),
     price: z.number().nonnegative().nullable().optional(),
     state: PartState.optional(),
     binId: z.string().uuid().nullable().optional(),
+    hostId: z.string().uuid().nullable().optional(),
     notes: z.string().max(4096).nullable().optional(),
     categoryId: z.string().uuid().nullable().optional(),
-    replacementPartId: z.string().uuid().nullable().optional(),
     tagIds: z.array(z.string().uuid()).max(32).optional(),
   })
   .refine((v) => Object.keys(v).length > 0, { message: 'At least one field required' });
@@ -36,6 +64,8 @@ export const PartListQuery = PaginationQuery.extend({
   state: PartState.optional(),
   binId: z.string().uuid().optional(),
   manufacturerId: z.string().uuid().optional(),
+  partModelId: z.string().uuid().optional(),
+  hostId: z.string().uuid().optional(),
   mpn: z.string().max(128).optional(),
   serialNumber: z.string().max(128).optional(),
   q: z.string().max(128).optional(),
@@ -56,6 +86,7 @@ export const BulkPartsRequest = z
     ids: z.array(z.string().uuid()).min(1).max(500),
     state: PartState.optional(),
     binId: z.string().uuid().nullable().optional(),
+    hostId: z.string().uuid().nullable().optional(),
     addTagIds: z.array(z.string().uuid()).max(32).optional(),
     removeTagIds: z.array(z.string().uuid()).max(32).optional(),
   })
@@ -63,6 +94,7 @@ export const BulkPartsRequest = z
     (v) =>
       v.state !== undefined ||
       v.binId !== undefined ||
+      v.hostId !== undefined ||
       (v.addTagIds && v.addTagIds.length > 0) ||
       (v.removeTagIds && v.removeTagIds.length > 0),
     { message: 'At least one mutation field is required' },
diff --git a/packages/shared/src/repairs.ts b/packages/shared/src/repairs.ts
index d28c237..d5525a8 100644
--- a/packages/shared/src/repairs.ts
+++ b/packages/shared/src/repairs.ts
@@ -3,8 +3,9 @@ import { RepairStatus } from './enums.js';
 import { PaginationQuery } from './pagination.js';
 
 export const CreateRepairJobRequest = z.object({
-  partId: z.string().uuid(),
-  hostId: z.string().uuid().optional().nullable(),
+  hostId: z.string().uuid(),
+  problem: z.string().trim().min(1, 'Problem is required').max(2000),
+  problemPartIds: z.array(z.string().uuid()).max(100).optional(),
   assigneeId: z.string().uuid().optional().nullable(),
   notes: z.string().max(4096).optional().nullable(),
 });
@@ -13,7 +14,8 @@ export type CreateRepairJobRequest = z.infer<typeof CreateRepairJobRequest>;
 export const UpdateRepairJobRequest = z
   .object({
     status: RepairStatus.optional(),
-    hostId: z.string().uuid().nullable().optional(),
+    problem: z.string().trim().min(1).max(2000).optional(),
+    problemPartIds: z.array(z.string().uuid()).max(100).optional(),
     assigneeId: z.string().uuid().nullable().optional(),
     notes: z.string().max(4096).nullable().optional(),
   })
@@ -22,8 +24,8 @@ export type UpdateRepairJobRequest = z.infer<typeof UpdateRepairJobRequest>;
 
 export const RepairJobListQuery = PaginationQuery.extend({
   status: RepairStatus.optional(),
-  partId: z.string().uuid().optional(),
   hostId: z.string().uuid().optional(),
+  problemPartId: z.string().uuid().optional(),
   assigneeId: z.string().uuid().optional(),
   openOnly: z
     .union([z.literal('true'), z.literal('false'), z.boolean()])
@@ -31,3 +33,11 @@ export const RepairJobListQuery = PaginationQuery.extend({
     .optional(),
 });
 export type RepairJobListQuery = z.infer<typeof RepairJobListQuery>;
+
+export const CreateRepairCommentRequest = z.object({
+  content: z.string().trim().min(1, 'Comment cannot be empty').max(4000),
+});
+export type CreateRepairCommentRequest = z.infer<typeof CreateRepairCommentRequest>;
+
+export const RepairCommentListQuery = PaginationQuery;
+export type RepairCommentListQuery = z.infer<typeof RepairCommentListQuery>;