From 8666e0271c2c9aaadd1f9119b55ee7347a8cad50 Mon Sep 17 00:00:00 2001
From: Cam Proudlock <cam.proudlock@gmail.com>
Date: Sat, 29 Aug 2026 19:09:06 -0400
Subject: [PATCH] Reciprocal controls links, dead chip links, and a resumable
 legacy import

The machine page now shows the PC that controls it. The endpoint was correct all
along and returned both directions; AssetTriageBand discarded every peer whose
type was not 'machine' and was mounted only on the PC page. The counterpart type,
label and relationship types are now props.

Fixed while adopting it more widely: every band chip linked to /assets/<id>, and
there is no such route. The resolver that AssetRelationships.vue kept privately
is now frontend/src/utils/assetRoute.js, used by both - and its type lookup is
case-insensitive, because seed data capitalises the type names while this site's
database does not.

The legacy import is now safe to resume. The 409-resolve asked for
per_page=10000 against a server that clamps to 100, so it silently searched the
first 100 rows and dropped links past that on every re-run. The crosswalk is now
bound to the database it describes, so one carried across a rebuild is refused
rather than attaching rows to the wrong assets. Source database names are
resolved from the environment, so the loader can be aimed without editing it.

Full suite 2178 passed, frontend 280 passed.
---
 .../src/components/AssetRelationships.vue     |  24 +--
 frontend/src/components/AssetTriageBand.vue   |  51 ++++--
 frontend/src/utils/assetRoute.js              |  43 +++++
 frontend/src/utils/assetRoute.spec.js         |  54 ++++++
 .../machines/frontend/views/MachineDetail.vue |  12 ++
 .../frontend/views/MeasuringToolDetail.vue    |  10 ++
 .../frontend/views/NetworkDeviceDetail.vue    |   9 +
 .../printers/frontend/views/PrinterDetail.vue |  11 ++
 scripts/site_imports/wjf/PILOT-DEPLOY.md      |  43 ++++-
 scripts/site_imports/wjf/README.md            |  34 +++-
 scripts/site_imports/wjf/harness.py           | 137 +++++++++++++--
 scripts/site_imports/wjf/run.py               | 138 +++++++++++++--
 .../test_relationship_directional.py          |  47 +++++
 tests/test_site_import_loader.py              | 164 ++++++++++++++++++
 14 files changed, 701 insertions(+), 76 deletions(-)
 create mode 100644 frontend/src/utils/assetRoute.js
 create mode 100644 frontend/src/utils/assetRoute.spec.js
 create mode 100644 tests/test_site_import_loader.py

diff --git a/frontend/src/components/AssetRelationships.vue b/frontend/src/components/AssetRelationships.vue
index 5aaf4afc..0b1d11b1 100644
--- a/frontend/src/components/AssetRelationships.vue
+++ b/frontend/src/components/AssetRelationships.vue
@@ -186,6 +186,7 @@
 </template>
 
 <script setup>
+import { assetRoute } from '@/utils/assetRoute'
 import { ref, computed, onMounted, watch } from 'vue'
 import { Cog, Monitor, Printer, Globe, Package, Ruler } from 'lucide-vue-next'
 import { assetsApi, relationshipTypesApi } from '../api'
@@ -472,28 +473,7 @@ function getAssetIcon(assettype) {
   return icons[assettype] || Package
 }
 
-function getAssetRoute(asset) {
-  if (!asset) return '#'
-
-  const routeMap = {
-    'machine': '/machines',
-    'computer': '/pcs',
-    'printer': '/printers',
-    'network_device': '/network',
-    'measuring_tool': '/measuringtools'
-  }
-
-  // serializer sends assettypename; old shape used assettype
-  const typename = asset.assettypename || asset.assettype
-  const basePath = routeMap[typename] || '/assets'
-
-  // pluginid is the extension-table id the detail routes key on
-  const id = asset.pluginid
-    || asset.typedata?.networkdeviceid
-    || asset.typedata?.machineid
-    || asset.assetid
-  return `${basePath}/${id}`
-}
+const getAssetRoute = assetRoute
 </script>
 
 <style scoped>
diff --git a/frontend/src/components/AssetTriageBand.vue b/frontend/src/components/AssetTriageBand.vue
index 270fc1c4..15556f89 100644
--- a/frontend/src/components/AssetTriageBand.vue
+++ b/frontend/src/components/AssetTriageBand.vue
@@ -8,13 +8,13 @@
     </div>
 
     <div v-if="machines.length" class="triage-item">
-      <span class="triage-label">{{ machines.length === 1 ? 'Serves machine' : 'Serves machines' }}</span>
+      <span class="triage-label">{{ counterpartheading }}</span>
       <span class="triage-values">
         <router-link
           v-for="machine in machines"
           :key="machine.assetid"
           class="triage-chip link"
-          :to="`/assets/${machine.assetid}`"
+          :to="assetRoute(machine)"
         >{{ machine.assetnumber || machine.name }}</router-link>
       </span>
     </div>
@@ -63,6 +63,7 @@
  */
 import { ref, computed, onMounted, watch, useSlots } from 'vue'
 import api from '@/api'
+import { assetRoute } from '@/utils/assetRoute'
 
 const props = defineProps({
   assetid: { type: Number, required: true },
@@ -71,11 +72,30 @@ const props = defineProps({
   // Shape: { level: 'ok'|'warning'|'critical'|'unknown', label: 'Reporting, 4m ago' }
   liveness: { type: Object, default: null },
   accessmethods: { type: Array, default: () => [] },
-  locationname: { type: String, default: '' }
+  locationname: { type: String, default: '' },
+  // Which side of a 'controls' edge this page wants to see, by asset type
+  // name. A PC page wants the machines it serves; a machine page wants the
+  // PCs that drive it. Defaults to 'machine' so the PC page - the only
+  // caller when this was written - keeps its exact behaviour.
+  counterparttype: { type: String, default: 'machine' },
+  // Overrides the heading. Empty keeps the shop-floor phrasing that earned
+  // its place: a PC matters because a machine stops without it.
+  counterpartlabel: { type: String, default: '' },
+  // Which relationship types link this asset to its counterpart. Not every
+  // pairing is 'controls': a PC controls a machine, but a machine reaches a
+  // printer through usesprinter and defaultprinter. Hardcoding 'controls'
+  // left the band blank on the printer page, which is the one page where the
+  // link is not obvious from the asset itself.
+  relationshiptypes: { type: Array, default: () => ['controls'] }
 })
 
 const machines = ref([])
 
+const counterpartheading = computed(() => {
+  if (props.counterpartlabel) return props.counterpartlabel
+  return machines.value.length === 1 ? 'Serves machine' : 'Serves machines'
+})
+
 const slots = useSlots()
 
 const hasAnything = computed(() =>
@@ -87,7 +107,7 @@ const hasAnything = computed(() =>
 )
 
 onMounted(loadMachines)
-watch(() => props.assetid, loadMachines)
+watch(() => [props.assetid, props.counterparttype, props.relationshiptypes], loadMachines)
 
 async function loadMachines() {
   machines.value = []
@@ -96,9 +116,11 @@ async function loadMachines() {
     const response = await api.get(`/assets/${props.assetid}/relationships`)
     const data = response.data.data || {}
     const found = []
-    // BOTH directions. The canonical edge is PC controls machine, but
-    // production also holds reciprocal rows, so reading one direction shows
-    // the link on half the pages and not the other half.
+    // BOTH directions, then deduped. Production holds reciprocal rows for
+    // the same link, so reading one direction shows it on half the pages and
+    // not the other half - and reading both without deduping shows it twice.
+    // Direction is therefore not trustworthy here and is deliberately not
+    // used to label anything.
     for (const edge of data.outgoing || []) collect(edge, edge.targetasset, found)
     for (const edge of data.incoming || []) collect(edge, edge.sourceasset, found)
     machines.value = found
@@ -111,10 +133,19 @@ async function loadMachines() {
 
 function collect(edge, other, found) {
   if (!other) return
-  if ((edge.relationshiptypename || '').toLowerCase() !== 'controls') return
-  if ((other.assettypename || '').toLowerCase() !== 'machine') return
+  const wanted = props.relationshiptypes.map(t => t.toLowerCase())
+  if (!wanted.includes((edge.relationshiptypename || '').toLowerCase())) return
+  if ((other.assettypename || '').toLowerCase() !== props.counterparttype.toLowerCase()) return
   if (found.some(m => m.assetid === other.assetid)) return
-  found.push({ assetid: other.assetid, assetnumber: other.assetnumber, name: other.name })
+  // pluginid and assettypename are what assetRoute() needs; without them the
+  // chip falls back to /assets/<assetid>, which is not a route.
+  found.push({
+    assetid: other.assetid,
+    assetnumber: other.assetnumber,
+    name: other.name,
+    pluginid: other.pluginid,
+    assettypename: other.assettypename
+  })
 }
 </script>
 
diff --git a/frontend/src/utils/assetRoute.js b/frontend/src/utils/assetRoute.js
new file mode 100644
index 00000000..36f96028
--- /dev/null
+++ b/frontend/src/utils/assetRoute.js
@@ -0,0 +1,43 @@
+/**
+ * Where an asset's detail page lives.
+ *
+ * Extracted from AssetRelationships.vue because a second caller appeared (the
+ * triage band) and got it wrong: it linked to `/assets/<assetid>`, which is not
+ * a route. There is no `/assets/:id` page and no catch-all, so every chip was a
+ * dead link. One copy, so a third caller cannot repeat it.
+ *
+ * Two ids are in play and they are not interchangeable. `assetid` is the core
+ * row; the detail routes key on `pluginid`, the id of the extension-table row
+ * (machineid, computerid, printerid). Sending assetid to /machines/:id opens
+ * the wrong machine, or none.
+ */
+
+// Asset type NAME to route base. The names are seed data, and seeding is not
+// consistent about case: shopdb/core/services/csvimport.py seeds 'Computer'
+// and 'Machine' capitalised, while this site's database holds them lowercase.
+// The lookup is therefore lowercased on both sides - a case-sensitive match
+// silently produced dead links at whichever site seeded the other way.
+const ROUTE_BY_TYPE = {
+  machine: '/machines',
+  computer: '/pcs',
+  printer: '/printers',
+  network_device: '/network',
+  'network device': '/network',
+  measuring_tool: '/measuringtools',
+  'measuring tool': '/measuringtools'
+}
+
+export function assetRoute(asset) {
+  if (!asset) return '#'
+
+  const typename = String(asset.assettypename || asset.assettype || '').toLowerCase()
+  const basePath = ROUTE_BY_TYPE[typename] || '/assets'
+
+  const id = asset.pluginid
+    || asset.typedata?.networkdeviceid
+    || asset.typedata?.machineid
+    || asset.assetid
+  return `${basePath}/${id}`
+}
+
+export default assetRoute
diff --git a/frontend/src/utils/assetRoute.spec.js b/frontend/src/utils/assetRoute.spec.js
new file mode 100644
index 00000000..819dbf74
--- /dev/null
+++ b/frontend/src/utils/assetRoute.spec.js
@@ -0,0 +1,54 @@
+import { describe, it, expect } from 'vitest'
+import { assetRoute } from './assetRoute'
+
+describe('assetRoute', () => {
+  // The bug this file exists to prevent: the triage band linked to
+  // /assets/<assetid>, and there is no /assets/:id route and no catch-all,
+  // so every chip was a dead link on five detail pages.
+  it('routes by asset type, never to /assets', () => {
+    expect(assetRoute({ assettypename: 'machine', pluginid: 223, assetid: 313 }))
+      .toBe('/machines/223')
+    expect(assetRoute({ assettypename: 'computer', pluginid: 279, assetid: 304 }))
+      .toBe('/pcs/279')
+    expect(assetRoute({ assettypename: 'printer', pluginid: 1, assetid: 594 }))
+      .toBe('/printers/1')
+  })
+
+  it('uses pluginid, not assetid - they are different rows', () => {
+    // /machines/:id keys on machineid. Passing assetid opens the wrong
+    // machine, or none, and looks like a data problem rather than a link bug.
+    const route = assetRoute({ assettypename: 'machine', pluginid: 223, assetid: 313 })
+    expect(route).toBe('/machines/223')
+    expect(route).not.toContain('313')
+  })
+
+  it('matches the type name whatever case the site seeded it in', () => {
+    // csvimport.py seeds 'Computer' and 'Machine' capitalised; this site's
+    // database holds them lowercase. A case-sensitive lookup produced dead
+    // links at whichever site seeded the other way.
+    expect(assetRoute({ assettypename: 'Computer', pluginid: 7 })).toBe('/pcs/7')
+    expect(assetRoute({ assettypename: 'MACHINE', pluginid: 8 })).toBe('/machines/8')
+  })
+
+  it('accepts the older assettype key as well as assettypename', () => {
+    expect(assetRoute({ assettype: 'printer', pluginid: 4 })).toBe('/printers/4')
+  })
+
+  it('falls back through typedata when pluginid is absent', () => {
+    expect(assetRoute({ assettypename: 'network_device', typedata: { networkdeviceid: 12 } }))
+      .toBe('/network/12')
+    expect(assetRoute({ assettypename: 'machine', typedata: { machineid: 30 } }))
+      .toBe('/machines/30')
+  })
+
+  it('returns a harmless anchor for nothing', () => {
+    expect(assetRoute(null)).toBe('#')
+    expect(assetRoute(undefined)).toBe('#')
+  })
+
+  it('handles both spellings of the multiword type names', () => {
+    expect(assetRoute({ assettypename: 'network device', pluginid: 2 })).toBe('/network/2')
+    expect(assetRoute({ assettypename: 'measuring_tool', pluginid: 3 })).toBe('/measuringtools/3')
+    expect(assetRoute({ assettypename: 'measuring tool', pluginid: 3 })).toBe('/measuringtools/3')
+  })
+})
diff --git a/plugins/machines/frontend/views/MachineDetail.vue b/plugins/machines/frontend/views/MachineDetail.vue
index fb48ed49..f9d49c88 100644
--- a/plugins/machines/frontend/views/MachineDetail.vue
+++ b/plugins/machines/frontend/views/MachineDetail.vue
@@ -70,6 +70,17 @@
               <span class="hero-detail-value">{{ machine.locationname }}</span>
             </div>
           </div>
+
+          <!-- The 6am band, machine side: which PCs drive this machine. The
+               same fact as a PC's "Serves machine", read from the other end -
+               and the end somebody is standing at when the machine has
+               stopped. It lived only in the relationships card near the
+               bottom of the page. -->
+          <AssetTriageBand
+            :assetid="machine.assetid"
+            counterparttype="computer"
+            counterpartlabel="Controlled by"
+          />
         </div>
       </div>
 
@@ -253,6 +264,7 @@ import { useRoute, useRouter } from 'vue-router'
 import { machinesApi } from '@/api'
 import { withBase } from '@/utils/basePath'
 import LocationMapTooltip from '@/components/LocationMapTooltip.vue'
+import AssetTriageBand from '@/components/AssetTriageBand.vue'
 import CustomFieldsSection from '@/components/CustomFieldsSection.vue'
 import PluginAssetPanels from '@/components/PluginAssetPanels.vue'
 import AssetRelationships from '@/components/AssetRelationships.vue'
diff --git a/plugins/measuringtools/frontend/views/MeasuringToolDetail.vue b/plugins/measuringtools/frontend/views/MeasuringToolDetail.vue
index dad0f38a..f92b7eb2 100644
--- a/plugins/measuringtools/frontend/views/MeasuringToolDetail.vue
+++ b/plugins/measuringtools/frontend/views/MeasuringToolDetail.vue
@@ -46,6 +46,15 @@
               <span class="hero-detail-value">{{ tool.locationname }}</span>
             </div>
           </div>
+
+          <!-- The 6am band. A gage usually has no controls edge at all,
+               and the band renders nothing when it has nothing to say - it is
+               here so the five asset pages stay one shape rather than five. -->
+          <AssetTriageBand
+            :assetid="tool.assetid"
+            counterparttype="machine"
+            counterpartlabel="Used on"
+          />
         </div>
       </div>
 
@@ -169,6 +178,7 @@ import { ref, onMounted } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import { colorStyle } from '@/utils/colorStyle'
 import { measuringtoolsApi } from '@/api'
+import AssetTriageBand from '@/components/AssetTriageBand.vue'
 import CustomFieldsSection from '@/components/CustomFieldsSection.vue'
 import PluginAssetPanels from '@/components/PluginAssetPanels.vue'
 import AssetRelationships from '@/components/AssetRelationships.vue'
diff --git a/plugins/network/frontend/views/NetworkDeviceDetail.vue b/plugins/network/frontend/views/NetworkDeviceDetail.vue
index 365654d7..e3c3d5ac 100644
--- a/plugins/network/frontend/views/NetworkDeviceDetail.vue
+++ b/plugins/network/frontend/views/NetworkDeviceDetail.vue
@@ -68,6 +68,14 @@
             <span class="hero-detail-value">{{ device.businessunitname }}</span>
           </div>
         </div>
+
+        <!-- The 6am band: what stops if this switch or AP goes down. A network
+             device is rarely interesting in itself; it matters because of what
+             sits behind it. -->
+        <AssetTriageBand
+          :assetid="device.assetid"
+          counterparttype="machine"
+        />
         <div class="hero-features" v-if="device.networkdevice">
           <span v-if="device.networkdevice.ispoe" class="feature-badge poe">PoE</span>
           <span v-if="device.networkdevice.ismanaged" class="feature-badge managed">Managed</span>
@@ -227,6 +235,7 @@ import { useAuthStore } from '@/stores/auth'
 import { networkApi } from '@/api'
 import { withBase } from '@/utils/basePath'
 import AssetRelationships from '@/components/AssetRelationships.vue'
+import AssetTriageBand from '@/components/AssetTriageBand.vue'
 import CustomFieldsSection from '@/components/CustomFieldsSection.vue'
 import PluginAssetPanels from '@/components/PluginAssetPanels.vue'
 import { useWarrantyBadge } from '@/composables/warrantyBadge'
diff --git a/plugins/printers/frontend/views/PrinterDetail.vue b/plugins/printers/frontend/views/PrinterDetail.vue
index d45af3b5..89979167 100644
--- a/plugins/printers/frontend/views/PrinterDetail.vue
+++ b/plugins/printers/frontend/views/PrinterDetail.vue
@@ -66,6 +66,16 @@
               <span class="hero-detail-value mono">{{ ipAddress }}</span>
             </div>
           </div>
+
+          <!-- The 6am band: which machine stops if this printer is down.
+               A shop-floor printer is often a label or tag printer feeding one
+               machine, and that link was only visible in the relationships
+               card near the bottom of the page. -->
+          <AssetTriageBand
+            :assetid="printer.assetid"
+            counterparttype="machine"
+            :relationshiptypes="['usesprinter', 'defaultprinter']"
+          />
         </div>
       </div>
 
@@ -301,6 +311,7 @@ import { useRoute, useRouter } from 'vue-router'
 import { printersApi } from '@/api'
 import { withBase } from '@/utils/basePath'
 import LocationMapTooltip from '@/components/LocationMapTooltip.vue'
+import AssetTriageBand from '@/components/AssetTriageBand.vue'
 import CustomFieldsSection from '@/components/CustomFieldsSection.vue'
 import PluginAssetPanels from '@/components/PluginAssetPanels.vue'
 import AssetRelationships from '@/components/AssetRelationships.vue'
diff --git a/scripts/site_imports/wjf/PILOT-DEPLOY.md b/scripts/site_imports/wjf/PILOT-DEPLOY.md
index 7bd2a0e6..119ccba8 100644
--- a/scripts/site_imports/wjf/PILOT-DEPLOY.md
+++ b/scripts/site_imports/wjf/PILOT-DEPLOY.md
@@ -78,9 +78,36 @@ import API. It is site glue, not product code.
      venv/bin/python -m scripts.site_imports.wjf.run
    ```
 
-   The 16 stages run in order (reference -> catalog -> assets hub -> locations ->
-   printers -> dependents -> relationships -> subnets -> usb -> verify). It is
-   idempotent - a crashed run resumes from `idmap.json`.
+   The 17 stages run in order (reference -> employees -> catalog -> assets hub
+   -> locations -> printers -> metrology -> communications -> applications ->
+   warranties -> notifications -> knowledgebase -> relationships ->
+   defaultprinters -> subnets -> usb -> verify).
+
+   **Pointing it at a different source.** The three source databases are
+   named logically in the loader and resolved from the environment, so a
+   restore under another name needs no code edit:
+
+   ```
+   SOURCE_DB_MAIN=prodscratch \
+   SOURCE_DB_USB=cmmc_usb_src \
+   SOURCE_DB_EMPLOYEES=wjf_employees_src \
+   DATABASE_URL=... venv/bin/python -m scripts.site_imports.wjf.run
+   ```
+
+   Also `SOURCE_DB_HOST`, `SOURCE_DB_PORT`, `SOURCE_DB_USER`,
+   `SOURCE_DB_PASSWORD`. The run prints every source it redirected, so
+   "it imported nothing" can be told apart from "it read the wrong database".
+
+   **Resume is per target database.** A crashed run resumes from the crosswalk
+   in `idmap.json`, which maps this site's legacy ids to assetids **in one
+   specific database**. The loader stamps that database's identity into the
+   file and refuses a crosswalk built against a different one, because reusing
+   it attaches warranties and printer assignments to whatever asset now holds
+   that id - wrong data, no error. If you rebuild the target, delete
+   `idmap.json` or pass `--idmap` a fresh path.
+
+   The exit code means something: non-zero if any endpoint errored, so a run
+   that logged 200 failures cannot read as a success in a deploy log.
 
 3. Reclassify servers into network devices. The classic DB stored servers as
    PCs, so the import lands them as `computer` assets. Re-point them in place:
@@ -151,8 +178,12 @@ documented skips (inactive rows, duplicate machinenumbers, LocationOnly, the
 - Keep the classic app authoritative during the window. The pilot is read-mostly
   for validation; do not dual-write.
 - Have a few real users (IT + a floor lead) work the pilot and log gaps.
-- Re-import is cheap: fix a loader mapping, drop + rebuild the pilot DB, re-run.
-  Nothing you do to the pilot touches classic.
+- Re-import is cheap: fix a loader mapping, drop + rebuild the pilot DB,
+  **delete `idmap.json`**, re-run. Nothing you do to the pilot touches classic.
+  The crosswalk is bound to the database it was built against and the loader
+  refuses a stale one, but deleting it is the habit to have - a refusal costs
+  you a restart, and before the guard existed a stale file silently attached
+  rows to the wrong assets.
 - Point the **collector** (GE-Enforce fleet ingest) at the pilot in parallel to
   confirm live PC check-ins land (see `COLLECTOR-INTEGRATION.md`), using a
   scoped service token.
@@ -163,7 +194,7 @@ When the window is clean:
 
 1. Freeze classic writes (announce a short read-only window).
 2. Take final fresh dumps; re-run the loader into a clean pilot DB so the
-   cutover data is current.
+   cutover data is current. A clean DB means a fresh `idmap.json` too.
 3. Verify counts + a fast UI spot-check.
 4. Repoint the production hostname/DNS (or the reverse proxy) at the pilot.
 5. Retire the classic app to read-only standby (do not delete - keep it as the
diff --git a/scripts/site_imports/wjf/README.md b/scripts/site_imports/wjf/README.md
index 0a2a9f09..d3351a19 100644
--- a/scripts/site_imports/wjf/README.md
+++ b/scripts/site_imports/wjf/README.md
@@ -33,16 +33,34 @@ resolved decisions, and remaining stages.
 
 ## Status
 
-Complete - all 15 stages built and verified end-to-end against a fresh scratch
-target (zero endpoint errors): `reference`, `employees`, `catalog`, `assets`
-(the hub + machineid->assetid crosswalk), `locations`, `printers`,
+All 17 stages built: `reference`, `employees`, `catalog`, `assets` (the hub +
+machineid->assetid crosswalk), `locations`, `printers`, `metrology`,
 `communications`, `applications` (+ installs), `warranties`, `notifications`,
-`knowledgebase`, `relationships`, `subnets`, `usb`, `verify`.
+`knowledgebase`, `relationships`, `defaultprinters`, `subnets`, `usb`, `verify`.
 
-Last full run: 983 assets (computer 663, machine 76, network 58, measuring-tool
-136, printer 50), 24 locations, 415 employees, 850 installs, 461 primary IPs,
-464 warranties, 261 notifications, 341 KB, 93 relationships, 37 subnets, 18 USB
-devices + 232 events. UI spot-check passed (computer list + shop-floor map).
+**The counts below are from the 2026-07-13 run and are STALE.** Two routing
+changes landed after them - the `isactive=1` filter and the metrology routing
+rework - so the asset mix has moved substantially. They are kept only as a
+shape, not as a checklist: re-measure from the next full run before quoting
+them anywhere, and do not verify a fresh import against them.
+
+Last full run (2026-07-13, superseded): 983 assets (computer 663, machine 76,
+network 58, measuring-tool 136, printer 50), 24 locations, 415 employees, 850
+installs, 461 primary IPs, 464 warranties, 261 notifications, 341 KB, 93
+relationships, 37 subnets, 18 USB devices + 232 events.
+
+Known gaps, none of them blocking a scratch run:
+
+- `warranties`, `notifications` and `knowledgebase` POST without a duplicate
+  check on the API side, so resuming ACROSS one of those stages doubles its
+  rows. Resuming at or after them is safe. Re-run into a clean target when in
+  doubt.
+- There is no `--dry-run` and no guard on the target: the harness mints an
+  admin PAT and sets `setup_complete` in whatever `DATABASE_URL` points at.
+  Check the target before running.
+- The `verify` stage counts target `assets` against source `machines`, which is
+  apples to oranges - the target also holds printers and synthesized metrology
+  tools.
 
 Known follow-ups: general asset `locationid` is null (no source column outside
 printers); the ~146 duplicate machinenumbers are first-wins-skipped by decision.
diff --git a/scripts/site_imports/wjf/harness.py b/scripts/site_imports/wjf/harness.py
index 89438a3d..4c41542a 100644
--- a/scripts/site_imports/wjf/harness.py
+++ b/scripts/site_imports/wjf/harness.py
@@ -14,6 +14,7 @@ crashed run resumes and later stages resolve foreign keys.
 """
 
 import json
+import uuid
 import os
 import pymysql
 
@@ -30,26 +31,63 @@ def _source_password():
     with open(os.path.abspath(env)) as handle:
         for line in handle:
             if line.startswith('DATABASE_URL='):
+                # Not every server runs as root, and 'root:' then simply is not
+                # there: split()[1] raised IndexError, which read as a crash
+                # rather than the clear message two lines down.
+                if 'root:' not in line:
+                    continue
                 after = line.split('root:', 1)[1]
                 return after.split('@', 1)[0]
     raise RuntimeError('could not resolve source DB password')
 
 
 class Source:
-    """Read-only access to the three scratch source databases."""
+    """Read-only access to the three source databases.
 
-    def __init__(self, host='127.0.0.1', port=3306, user='root', password=None):
+    The stage functions name a source by its LOGICAL name - 'shopdb_src',
+    'cmmc_usb_src', 'wjf_employees_src' - and this class resolves each to a
+    real database. That indirection is the point: the names were hardcoded at
+    29 call sites, so pointing the loader at a differently-named copy (the
+    prodscratch restore, or a site's own dump) meant editing run.py, which is
+    not something anybody should do to aim a loader. The logical names stay in
+    the stages where they read as documentation; the mapping lives here.
+
+    Everything is environment-overridable, defaulting to the scratch layout:
+
+        SOURCE_DB_MAIN        default shopdb_src
+        SOURCE_DB_USB         default cmmc_usb_src
+        SOURCE_DB_EMPLOYEES   default wjf_employees_src
+        SOURCE_DB_HOST/PORT/USER/PASSWORD
+    """
+
+    # logical name -> (env var, default real name)
+    ALIASES = {
+        'shopdb_src': ('SOURCE_DB_MAIN', 'shopdb_src'),
+        'cmmc_usb_src': ('SOURCE_DB_USB', 'cmmc_usb_src'),
+        'wjf_employees_src': ('SOURCE_DB_EMPLOYEES', 'wjf_employees_src'),
+    }
+
+    def __init__(self, host=None, port=None, user=None, password=None):
         self.password = password or _source_password()
-        self.host, self.port, self.user = host, port, user
+        self.host = host or os.environ.get('SOURCE_DB_HOST', '127.0.0.1')
+        self.port = int(port or os.environ.get('SOURCE_DB_PORT', 3306))
+        self.user = user or os.environ.get('SOURCE_DB_USER', 'root')
         self._conns = {}
 
+    @classmethod
+    def resolve(cls, name):
+        """The real database behind a logical source name."""
+        env, default = cls.ALIASES.get(name, (None, name))
+        return os.environ.get(env, default) if env else name
+
     def db(self, name):
-        if name not in self._conns:
-            self._conns[name] = pymysql.connect(
+        real = self.resolve(name)
+        if real not in self._conns:
+            self._conns[real] = pymysql.connect(
                 host=self.host, port=self.port, user=self.user,
-                password=self.password, database=name, charset='utf8mb4',
+                password=self.password, database=real, charset='utf8mb4',
                 cursorclass=pymysql.cursors.DictCursor)
-        return self._conns[name]
+        return self._conns[real]
 
     def rows(self, dbname, sql, args=None):
         with self.db(dbname).cursor() as cur:
@@ -57,15 +95,62 @@ class Source:
             return cur.fetchall()
 
 
-class IdMap:
-    """Persisted legacy-id -> new-id crosswalks, one namespace per entity."""
+class StaleIdMapError(RuntimeError):
+    """The crosswalk on disk was built against a different target database."""
 
-    def __init__(self, path):
+
+class IdMap:
+    """Persisted legacy-id -> new-id crosswalks, one namespace per entity.
+
+    BOUND TO ONE TARGET DATABASE. The crosswalk holds this site's legacy ids
+    mapped to assetids in a specific database, and those assetids mean nothing
+    anywhere else. Two ways that used to go wrong, both silent:
+
+      - Delete idmap.json and re-run: every create 409s, nothing resolves into
+        the crosswalk, and warranties, installs, relationships and printer
+        assignments all quietly import as ~0 rows.
+      - Keep idmap.json across a drop-and-rebuild of the target: the legacy ids
+        now point at assetids belonging to the OLD database, so warranties and
+        printer assignments attach to whatever asset happens to hold that id
+        now. Wrong data, no error, and the runbook's two "drop and rebuild"
+        steps never said to delete the file.
+
+    The bind is a marker row in the target's own settings table, so it dies
+    with the data: a rebuild produces a new marker, and the mismatch is caught
+    before a single row is written. The database NAME is not enough on its own,
+    because a rebuild keeps it.
+    """
+
+    MARKER_KEY = 'siteimport_targetinstance'
+
+    def __init__(self, path, target=None):
         self.path = path
+        self.target = target
         self._data = {}
         if os.path.exists(path):
             with open(path) as handle:
                 self._data = json.load(handle)
+            self._check_target()
+
+    def _check_target(self):
+        if not self.target:
+            return
+        seen = self._data.get('_target')
+        if seen is None:
+            # Written before this check existed. Adopt it rather than refuse:
+            # refusing would strand a crosswalk that is probably fine, and the
+            # next run is bound properly.
+            self._data['_target'] = self.target
+            self.save()
+            return
+        if seen != self.target:
+            raise StaleIdMapError(
+                '%s was built against target %s, but this run targets %s.\n'
+                'Those assetids belong to a different database and using them '
+                'would attach imported rows to the wrong assets.\n'
+                'Delete the file to start a fresh crosswalk, or point '
+                '--idmap at the one for this target.'
+                % (self.path, seen, self.target))
 
     def put(self, namespace, legacy, new):
         self._data.setdefault(namespace, {})[str(legacy)] = new
@@ -78,7 +163,8 @@ class IdMap:
         return str(legacy) in self._data.get(namespace, {})
 
     def count(self, namespace):
-        return len(self._data.get(namespace, {}))
+        entry = self._data.get(namespace, {})
+        return len(entry) if isinstance(entry, dict) else 0
 
     def save(self):
         with open(self.path, 'w') as handle:
@@ -97,11 +183,38 @@ class Harness:
         self._ensure_asset_types()
         self.secret = self._mint_admin_pat()
         default = os.path.join(os.path.dirname(__file__), 'idmap.json')
-        self.ids = IdMap(idmap_path or default)
+        self.ids = IdMap(idmap_path or default, target=self._target_instance())
         self.source = Source()
         self.errors = []
         self._defaultlevelid = None
 
+    def _target_instance(self):
+        """A stable id for THIS target database, created once and stored in it.
+
+        Kept in the target's own settings table so it dies when the data does.
+        A drop-and-rebuild yields a new id, which is what lets IdMap catch a
+        crosswalk carried over from the previous database - the failure that
+        silently attaches imported rows to whatever asset now holds that id.
+
+        The database name alone would not do: a rebuild keeps the name.
+        """
+        from shopdb.core.models import Setting
+        existing = Setting.query.filter_by(key=IdMap.MARKER_KEY).first()
+        if existing and existing.value:
+            return existing.value
+        marker = uuid.uuid4().hex
+        if existing:
+            existing.value = marker
+        else:
+            db.session.add(Setting(
+                key=IdMap.MARKER_KEY, value=marker, valuetype='string',
+                category='import',
+                description='Identifies this database to the site-import '
+                            'crosswalk. Created by the loader; do not copy it '
+                            'between databases.'))
+        db.session.commit()
+        return marker
+
     @property
     def defaultlevelid(self):
         """The level imported map positions belong to (ADR-017).
diff --git a/scripts/site_imports/wjf/run.py b/scripts/site_imports/wjf/run.py
index 034eabd2..43044940 100644
--- a/scripts/site_imports/wjf/run.py
+++ b/scripts/site_imports/wjf/run.py
@@ -9,16 +9,19 @@ Stages are idempotent (re-running resolves existing rows by natural key), so a
 crashed run resumes. See scripts/site_imports/wjf/harness.py for the contract
 this drives, and scratchpad/IMPORT-PLAN.md for the full mapping + decisions.
 
-Implemented: reference (vendors, businessunits, operatingsystems), employees.
-TODO stages (assets hub + dependents + network + usb) are stubbed - they need
-the machineid->assetid crosswalk this harness persists.
+All 17 stages are implemented; STAGES at the bottom of this file is the list
+and main()'s --stages default is the order they must run in. The assets hub
+comes before everything that references an asset, because it is what builds the
+machineid->assetid crosswalk the harness persists.
 """
 
 import argparse
+import sys
+from urllib.parse import quote
 
 import pymysql
 
-from .harness import Harness
+from .harness import Harness, Source, StaleIdMapError
 
 
 def _id_of(row, idfield):
@@ -33,6 +36,76 @@ def _id_of(row, idfield):
     return None
 
 
+# The server clamps any page size to MAX_PAGE_SIZE (shopdb/config.py), which
+# is 100. Asking for more is not an error and not a warning - it just silently
+# returns 100 rows, which is why the 409-resolve below pages instead.
+PAGE_SIZE = 100
+
+# A resolve that walks more pages than this is a bug in the caller, not a big
+# table. Bounded so a paging mistake cannot spin forever against a live server.
+MAX_RESOLVE_PAGES = 200
+
+
+def _rows_of(payload):
+    """The list out of a list-endpoint response, whichever shape it took."""
+    if isinstance(payload, list):
+        return payload
+    if isinstance(payload, dict):
+        items = payload.get('items')
+        if isinstance(items, list):
+            return items
+    return []
+
+
+def _resolve_existing(h, lookup, unique_field, wanted, idfield):
+    """Find an existing row by its natural key. Returns its id, or None.
+
+    This used to ask for ?per_page=10000 and read the single response. The
+    server clamps per_page to 100, so it only ever searched the first 100 rows
+    and returned None for everything after that. The failure was silent and
+    downstream: _upsert returned None, the id never reached the crosswalk, and
+    the run finished "successfully" having quietly dropped a model's link on
+    every machine that used it. The target already holds more than 100 models
+    and more than 100 applications, so this fired on any re-run or resume - the
+    exact case the loader documents as safe.
+
+    Two passes. Some endpoints expose an exact natural-key filter for this
+    (?modelnumber= on models, ?appname= on applications, ?vendor= on vendors);
+    an endpoint without one ignores the unknown query parameter and returns its
+    normal first page, so the paged walk that follows is what finds the row.
+    """
+    wanted_key = str(wanted).strip().lower()
+    separator = '&' if '?' in lookup else '?'
+
+    def match(rows):
+        for row in rows:
+            if str(row.get(unique_field, '')).strip().lower() == wanted_key:
+                return _id_of(row, idfield)
+        return None
+
+    # Pass 1: the exact filter, where the endpoint has one.
+    exact = '%s%s%s=%s&per_page=%d' % (
+        lookup, separator, unique_field, quote(str(wanted)), PAGE_SIZE)
+    _, data = h.get(exact)
+    found = match(_rows_of(data))
+    if found is not None:
+        return found
+
+    # Pass 2: every page, in order.
+    for page in range(1, MAX_RESOLVE_PAGES + 1):
+        _, data = h.get('%s%sper_page=%d&page=%d'
+                        % (lookup, separator, PAGE_SIZE, page))
+        rows = _rows_of(data)
+        if not rows:
+            return None
+        found = match(rows)
+        if found is not None:
+            return found
+        if len(rows) < PAGE_SIZE:
+            return None
+    return None
+
+
 def _upsert(h, path, payload, unique_field, idfield, list_path=None):
     """POST payload; on 409 resolve the existing row by its unique field.
     Returns the new/existing id, or None."""
@@ -40,14 +113,8 @@ def _upsert(h, path, payload, unique_field, idfield, list_path=None):
     if status in (200, 201):
         return _id_of(data, idfield)
     if status == 409:
-        lookup = list_path or path
-        lookup += ('&' if '?' in lookup else '?') + 'per_page=10000'
-        _, rows = h.get(lookup)
-        items = rows if isinstance(rows, list) else rows.get('items', rows)
-        for row in (items or []):
-            if str(row.get(unique_field, '')).strip().lower() == \
-                    str(payload[unique_field]).strip().lower():
-                return _id_of(row, idfield)
+        return _resolve_existing(h, list_path or path, unique_field,
+                                 payload[unique_field], idfield)
     return None
 
 
@@ -418,10 +485,22 @@ def stage_metrology(h):
             'businessunitid': h.ids.get('businessunit', m['businessunitid']),
             'mapx': m['mapleft'], 'mapy': m['maptop'],
             'levelid': h.defaultlevelid})
-        if status not in (200, 201):
+        if status in (200, 201):
+            tool_assetid = _id_of(data, 'assetid')
+            made += 1
+        elif status == 409:
+            # Already imported by an earlier run. Resolve it rather than
+            # skipping: `continue` here left the crosswalk without this tool,
+            # so the Controls edge below was never made and a resumed run
+            # produced metrology PCs driving nothing. stage_printers already
+            # had this branch; this stage was written later and missed it.
+            tool_assetid = _resolve_existing(
+                h, '/api/measuringtools', 'assetnumber',
+                f"MT-{m['machineid']}", 'assetid')
+            if not tool_assetid:
+                continue
+        else:
             continue
-        tool_assetid = _id_of(data, 'assetid')
-        made += 1
         if tool_assetid and controls_id:
             h.ids.put('metrologytool', m['machineid'], tool_assetid)
             st, _ = h.post('/api/assets/relationships', {
@@ -906,10 +985,27 @@ def main():
                 'metrology,communications,applications,warranties,notifications,'
                 'knowledgebase,relationships,defaultprinters,subnets,usb,verify',
         help='comma list of stages to run')
+    parser.add_argument(
+        '--idmap', default=None,
+        help='path to the legacy-id crosswalk (default: idmap.json beside '
+             'this script). One per target database - a crosswalk from '
+             'another database maps to the wrong assets.')
     args = parser.parse_args()
 
-    h = Harness()
-    print(f'== WJ import loader (target: {h.app.config["SQLALCHEMY_DATABASE_URI"].split("/")[-1]}) ==')
+    try:
+        h = Harness(idmap_path=args.idmap)
+    except StaleIdMapError as error:
+        print('REFUSED: %s' % error)
+        return 1
+
+    target = h.app.config['SQLALCHEMY_DATABASE_URI'].split('/')[-1]
+    print(f'== WJ import loader (target: {target}) ==')
+    # Say which sources this run reads. They are overridable now, so "it
+    # imported nothing" is usually "it read the wrong database".
+    for logical in ('shopdb_src', 'cmmc_usb_src', 'wjf_employees_src'):
+        real = Source.resolve(logical)
+        if real != logical:
+            print(f'   source {logical} -> {real}')
     try:
         for name in args.stages.split(','):
             name = name.strip()
@@ -922,9 +1018,15 @@ def main():
             print(f'\n  {len(h.errors)} endpoint error(s):')
             for path, code, _payload, data in h.errors[:10]:
                 print(f'    {code} {path}: {data}')
+        # An endpoint error is not a crash, but it did leave rows unimported,
+        # and a run that exits 0 after 200 of them looks like a success in a
+        # deploy log.
+        if h.errors:
+            return 1
     finally:
         h.close()
+    return 0
 
 
 if __name__ == '__main__':
-    main()
+    sys.exit(main())
diff --git a/tests/test_core/test_relationship_directional.py b/tests/test_core/test_relationship_directional.py
index 4067b531..5cdf3667 100644
--- a/tests/test_core/test_relationship_directional.py
+++ b/tests/test_core/test_relationship_directional.py
@@ -104,3 +104,50 @@ def test_relationships_row_carries_isdirectional(client, db, auth_headers):
     ctrl_rows = [r for r in data['outgoing']
                  if r['relationshiptypename'] == 'controls']
     assert ctrl_rows and all(r['isdirectional'] is True for r in ctrl_rows)
+
+def test_the_controlled_asset_sees_the_link_from_its_own_page(client, db, auth_headers):
+    """The target of a directional edge must receive it in `incoming`.
+
+    A PC controls a machine, and the row is stored once, source=PC. The PC's
+    page reads it from `outgoing`; the machine's page can only ever see it in
+    `incoming`. Nothing asserted that second half, and a UI was shipped that
+    rendered the link on the PC page and showed the machine page nothing - the
+    reciprocal-links defect. The endpoint was correct all along, which is
+    exactly why this assertion is worth having: it pins the contract the
+    frontend depends on, so the next such bug cannot be blamed on the API.
+    """
+    atype_machine = AssetType(assettype='machine')
+    atype_computer = AssetType(assettype='computer')
+    db.session.add_all([atype_machine, atype_computer])
+    db.session.flush()
+
+    controls = RelationshipType(relationshiptype='controls', isdirectional=True)
+    db.session.add(controls)
+    db.session.flush()
+
+    pc = _make_asset('PC-1', atype_computer.assettypeid)
+    machine = _make_asset('M-1', atype_machine.assettypeid)
+
+    # Stored ONCE, in the canonical direction only.
+    db.session.add(AssetRelationship(sourceassetid=pc.assetid,
+                                     targetassetid=machine.assetid,
+                                     relationshiptypeid=controls.relationshiptypeid))
+    db.session.commit()
+
+    resp = client.get(f'/api/assets/{machine.assetid}/relationships',
+                      headers=auth_headers)
+    assert resp.status_code == 200
+    data = resp.get_json()['data']
+
+    assert data['outgoing'] == [], 'the machine controls nothing'
+    assert len(data['incoming']) == 1, 'the machine must see the PC that controls it'
+
+    row = data['incoming'][0]
+    assert row['relationshiptypename'] == 'controls'
+    # The peer has to arrive with the fields the UI routes on. assetid alone
+    # is not enough: the detail routes key on pluginid, and the type name
+    # chooses the route base.
+    peer = row['sourceasset']
+    assert peer is not None
+    assert peer['assetid'] == pc.assetid
+    assert peer['assettypename'] == 'computer'
diff --git a/tests/test_site_import_loader.py b/tests/test_site_import_loader.py
new file mode 100644
index 00000000..7b0d7f34
--- /dev/null
+++ b/tests/test_site_import_loader.py
@@ -0,0 +1,164 @@
+"""The WJ reference loader's resolve, crosswalk binding and source aliasing.
+
+The loader had no tests at all, and three of its defects were the silent kind:
+they did not raise, they imported fewer rows and finished cheerfully. These
+cover the logic that can be exercised without a MySQL source, which is exactly
+the part that was wrong.
+
+Not covered here: the stage functions themselves. They need the classic source
+schema, so they belong in a fixture-backed integration test against a scratch
+database, not in the unit suite.
+"""
+import json
+import os
+
+import pytest
+
+from scripts.site_imports.wjf import run as loader
+from scripts.site_imports.wjf.harness import IdMap, Source, StaleIdMapError
+
+
+class FakeHarness:
+    """Records the paths requested and replays canned list responses."""
+
+    def __init__(self, pages):
+        self.pages = pages
+        self.requested = []
+
+    def get(self, path):
+        self.requested.append(path)
+        return 200, self.pages.get(path, {'items': []})
+
+
+class TestResolveExisting:
+    def test_finds_a_row_beyond_the_first_page(self):
+        """The bug: per_page is clamped to 100, so row 101 was invisible.
+
+        The old code asked for per_page=10000, read one response, and returned
+        None for anything the server did not fit in its first 100 rows. The
+        target already holds more than 100 models and more than 100
+        applications, so this fired on every resume.
+        """
+        page1 = {'items': [{'modelnumber': 'M%03d' % i, 'modelnumberid': i}
+                           for i in range(100)]}
+        page2 = {'items': [{'modelnumber': 'LATE', 'modelnumberid': 999}]}
+        harness = FakeHarness({
+            '/api/models?modelnumber=LATE&per_page=100': {'items': []},
+            '/api/models?per_page=100&page=1': page1,
+            '/api/models?per_page=100&page=2': page2,
+        })
+        found = loader._resolve_existing(
+            harness, '/api/models', 'modelnumber', 'LATE', 'modelnumberid')
+        assert found == 999
+
+    def test_tries_the_exact_filter_first(self):
+        harness = FakeHarness({
+            '/api/models?modelnumber=WIDGET&per_page=100':
+                {'items': [{'modelnumber': 'WIDGET', 'modelnumberid': 7}]},
+        })
+        assert loader._resolve_existing(
+            harness, '/api/models', 'modelnumber', 'WIDGET', 'modelnumberid') == 7
+        # One request: it must not walk every page when the filter answered.
+        assert len(harness.requested) == 1
+
+    def test_values_needing_encoding_do_not_break_the_filter(self):
+        harness = FakeHarness({})
+        loader._resolve_existing(harness, '/api/vendors', 'vendor',
+                                 'Acme & Co/Ltd', 'vendorid')
+        assert 'Acme%20%26%20Co/Ltd' in harness.requested[0] or \
+               'Acme%20%26%20Co%2FLtd' in harness.requested[0]
+
+    def test_matching_ignores_case_and_padding(self):
+        harness = FakeHarness({
+            '/api/vendors?vendor=acme&per_page=100':
+                {'items': [{'vendor': '  ACME ', 'vendorid': 3}]},
+        })
+        assert loader._resolve_existing(
+            harness, '/api/vendors', 'vendor', 'acme', 'vendorid') == 3
+
+    def test_missing_row_returns_none_without_spinning(self):
+        harness = FakeHarness({})
+        assert loader._resolve_existing(
+            harness, '/api/models', 'modelnumber', 'NOPE', 'modelnumberid') is None
+        # Empty first page ends it: the filter attempt plus one page.
+        assert len(harness.requested) == 2
+
+    def test_a_short_page_ends_the_walk(self):
+        harness = FakeHarness({
+            '/api/models?per_page=100&page=1': {'items': [{'modelnumber': 'A', 'modelnumberid': 1}]},
+        })
+        assert loader._resolve_existing(
+            harness, '/api/models', 'modelnumber', 'ZZZ', 'modelnumberid') is None
+        assert len(harness.requested) == 2
+
+    def test_a_bare_list_response_is_accepted(self):
+        harness = FakeHarness({
+            '/api/x?name=a&per_page=100': [{'name': 'a', 'id': 5}],
+        })
+        assert loader._resolve_existing(harness, '/api/x', 'name', 'a', 'id') == 5
+
+    def test_an_existing_query_string_keeps_its_separator(self):
+        harness = FakeHarness({})
+        loader._resolve_existing(harness, '/api/models?category=pc',
+                                 'modelnumber', 'M1', 'modelnumberid')
+        assert harness.requested[0].startswith('/api/models?category=pc&modelnumber=')
+
+
+class TestIdMapBinding:
+    def test_a_crosswalk_from_another_database_is_refused(self, tmp_path):
+        """The silent corruption this guard exists for.
+
+        Keeping idmap.json across a drop-and-rebuild leaves legacy ids pointing
+        at assetids from the OLD database, so warranties and printer
+        assignments attach to whatever asset holds that id now. No error, wrong
+        data.
+        """
+        path = tmp_path / 'idmap.json'
+        path.write_text(json.dumps({'_target': 'aaaa', 'asset': {'1': 10}}))
+        with pytest.raises(StaleIdMapError) as caught:
+            IdMap(str(path), target='bbbb')
+        assert 'different database' in str(caught.value)
+
+    def test_the_matching_target_loads(self, tmp_path):
+        path = tmp_path / 'idmap.json'
+        path.write_text(json.dumps({'_target': 'aaaa', 'asset': {'1': 10}}))
+        ids = IdMap(str(path), target='aaaa')
+        assert ids.get('asset', 1) == 10
+
+    def test_an_unstamped_crosswalk_is_adopted_not_refused(self, tmp_path):
+        # Written before the guard existed. Refusing would strand a crosswalk
+        # that is probably fine; adopting binds it for every run after.
+        path = tmp_path / 'idmap.json'
+        path.write_text(json.dumps({'asset': {'1': 10}}))
+        ids = IdMap(str(path), target='ccc')
+        assert ids.get('asset', 1) == 10
+        assert json.loads(path.read_text())['_target'] == 'ccc'
+
+    def test_the_bookkeeping_key_is_not_counted_as_a_namespace(self, tmp_path):
+        path = tmp_path / 'idmap.json'
+        ids = IdMap(str(path), target='ccc')
+        ids.put('asset', 1, 10)
+        assert ids.count('asset') == 1
+        assert ids.count('_target') == 0
+
+    def test_a_fresh_crosswalk_needs_no_stamp_to_start(self, tmp_path):
+        ids = IdMap(str(tmp_path / 'new.json'), target='ddd')
+        ids.put('asset', 5, 50)
+        assert ids.get('asset', 5) == 50
+
+
+class TestSourceAliasing:
+    def test_logical_names_default_to_the_scratch_databases(self, monkeypatch):
+        for var in ('SOURCE_DB_MAIN', 'SOURCE_DB_USB', 'SOURCE_DB_EMPLOYEES'):
+            monkeypatch.delenv(var, raising=False)
+        assert Source.resolve('shopdb_src') == 'shopdb_src'
+        assert Source.resolve('cmmc_usb_src') == 'cmmc_usb_src'
+        assert Source.resolve('wjf_employees_src') == 'wjf_employees_src'
+
+    def test_the_environment_repoints_the_loader(self, monkeypatch):
+        """What unblocks the prodscratch run without editing run.py."""
+        monkeypatch.setenv('SOURCE_DB_MAIN', 'prodscratch')
+        assert Source.resolve('shopdb_src') == 'prodscratch'
+
+    def test_an_unknown_name_passes_through(self, monkeypatch):
+        assert Source.resolve('something_else') == 'something_else'