diff --git a/cloud/apps/relay/src/relay-observability.test.ts b/cloud/apps/relay/src/relay-observability.test.ts
index edc1f7c71f1..22802b7f8aa 100644
--- a/cloud/apps/relay/src/relay-observability.test.ts
+++ b/cloud/apps/relay/src/relay-observability.test.ts
@@ -1,4 +1,4 @@
-import { RELAY_REGIONS } from '@orca-cloud/relay-contract'
+import { RELAY_REGION_METRIC_SEGMENTS, RELAY_REGIONS } from '@orca-cloud/relay-contract'
 import { describe, expect, it, vi } from 'vitest'
 import type { RelayDatabase } from './database.js'
 import { observeRelayDatabase } from './observed-relay-database.js'
@@ -133,14 +133,11 @@ describe('relay observability', () => {
     })
     // A region added to the contract has to reach the flat keys, or the skew alert's
     // denominator silently misses it.
-    for (const region of RELAY_REGIONS) {
-      const segment = region
-        .split('-')
-        .map((part) => part.charAt(0).toUpperCase() + part.slice(1))
-        .join('')
+    for (const segment of Object.values(RELAY_REGION_METRIC_SEGMENTS)) {
       expect(entries[0]).toHaveProperty(`requestedRegion${segment}Delta`)
       expect(entries[0]).toHaveProperty(`selectedRegion${segment}Delta`)
     }
+    expect(Object.keys(RELAY_REGION_METRIC_SEGMENTS).sort()).toEqual([...RELAY_REGIONS].sort())
   })
 
   it('emits bounded aggregate runtime signals without identities or credentials', () => {
diff --git a/cloud/apps/relay/src/relay-observability.ts b/cloud/apps/relay/src/relay-observability.ts
index ac574fdcb89..9f937afdb6e 100644
--- a/cloud/apps/relay/src/relay-observability.ts
+++ b/cloud/apps/relay/src/relay-observability.ts
@@ -1,5 +1,5 @@
 import { monitorEventLoopDelay, performance } from 'node:perf_hooks'
-import { RELAY_REGIONS, type RelayRegion } from '@orca-cloud/relay-contract'
+import { RELAY_REGION_METRIC_SEGMENTS, type RelayRegion } from '@orca-cloud/relay-contract'
 import type { ControlRenewalOutcome } from './assignment-store.js'
 import type { CellInventoryHoldCounts } from './cell-inventory-hold-samples.js'
 import type { PostgresPoolPressureCounts } from './postgres-pool-pressure.js'
@@ -419,20 +419,13 @@ export class RelayObservability implements RelayRuntimeObserver {
 // A log-based metric cannot reach `requestedRegionsDelta."asia-east2"` without a quoted field
 // path, and an absent key would drop a series out of the inner join the region-skew alert does.
 // The maps stay authoritative and keep carrying anything outside the catalog, such as `unhinted`.
-function regionFieldSegment(region: RelayRegion): string {
-  return region
-    .split('-')
-    .map((part) => part.charAt(0).toUpperCase() + part.slice(1))
-    .join('')
-}
-
 function regionCounterFields(
   prefix: 'requestedRegion' | 'selectedRegion',
   counts: Record<string, number>
 ): Record<string, number> {
   return Object.fromEntries(
-    RELAY_REGIONS.map((region) => [
-      `${prefix}${regionFieldSegment(region)}Delta`,
+    Object.entries(RELAY_REGION_METRIC_SEGMENTS).map(([region, segment]) => [
+      `${prefix}${segment}Delta`,
       counts[region] ?? 0
     ])
   )
diff --git a/cloud/dev/scripts/relay-region-hint-metrics.test.mjs b/cloud/dev/scripts/relay-region-hint-metrics.test.mjs
index 3f891009099..8f331efce18 100644
--- a/cloud/dev/scripts/relay-region-hint-metrics.test.mjs
+++ b/cloud/dev/scripts/relay-region-hint-metrics.test.mjs
@@ -19,7 +19,6 @@ const contractRegions = (() => {
 })()
 
 const terraform = read('../../infra/terraform/relay-observability.tf')
-const emitter = read('../../apps/relay/src/relay-observability.ts')
 
 const terraformRegions = (() => {
   const literal = /relay_region_keys = \[([^\]]*)\]/.exec(terraform)
@@ -27,26 +26,35 @@ const terraformRegions = (() => {
   return [...literal[1].matchAll(/"([^"]+)"/g)].map((match) => match[1])
 })()
 
+// Both sides now spell the field-name segments out, so the test compares the two declared maps
+// rather than two source expressions. Reformatting either file cannot break this, and a literal
+// expected value below still catches an identical wrong edit made to both.
+const declaredSegments = (source, open, close) => {
+  const body = source.slice(source.indexOf(open) + open.length, source.indexOf(close, source.indexOf(open)))
+  return Object.fromEntries(
+    [...body.matchAll(/'?"?([a-z0-9-]+)'?"?\s*[:=]\s*'?"?([A-Za-z0-9]+)'?"?/g)].map((match) => [
+      match[1],
+      match[2]
+    ])
+  )
+}
+
+const terraformSegments = declaredSegments(terraform, 'relay_region_field_segments = {', '}')
+const contractSegments = declaredSegments(
+  read('../../packages/relay-contract/src/relay-regions.ts'),
+  'RELAY_REGION_METRIC_SEGMENTS = {',
+  '}'
+)
+
 test('terraform covers exactly the regions the contract can hint or select', () => {
   assert.deepEqual([...terraformRegions].sort(), [...contractRegions].sort())
 })
 
-test('terraform and the emitter derive the same flat field names', () => {
-  // Both build `<prefix><Segment>Delta` from the hyphenated region id: Terraform title-cases each
-  // dash-separated part, the emitter upper-cases each part's first character. Same result, two
-  // languages, so the rules are pinned rather than the rendered names.
-  assert.match(collapse(terraform), /join\("", \[for part in split\("-", key\) : title\(part\)\]\)/)
-  assert.match(
-    collapse(emitter),
-    /\.split\('-'\) \.map\(\(part\) => part\.charAt\(0\)\.toUpperCase\(\) \+ part\.slice\(1\)\)/
-  )
-  for (const prefix of ['requestedRegion', 'selectedRegion']) {
-    assert.ok(
-      terraform.includes(`${prefix}\${local.relay_region_field_segments[key]}Delta`),
-      `terraform does not build ${prefix}<Segment>Delta`
-    )
-    assert.ok(emitter.includes(`'${prefix}'`), `the emitter does not publish ${prefix} counters`)
-  }
+test('terraform and the contract declare the same flat field segments', () => {
+  assert.deepEqual(terraformSegments, contractSegments)
+  // Pinned literally so the same wrong edit applied to both sides still fails.
+  assert.deepEqual(terraformSegments, { 'us-central1': 'UsCentral1', 'asia-east2': 'AsiaEast2' })
+  assert.deepEqual(Object.keys(terraformSegments).sort(), [...contractRegions].sort())
 })
 
 test('the skew query compares a catalogued region against itself', () => {
@@ -58,6 +66,16 @@ test('the skew query compares a catalogued region against itself', () => {
   assert.ok(columns.includes(hint[1]), `${hint[1]} is not one of ${columns.join(', ')}`)
 })
 
+test('the skew condition never divides by the placement share', () => {
+  // A zero-placement hour is the worst skew there is; MQL drops the row on x/0, so the ratio form
+  // silences exactly the case the alert exists for.
+  assert.ok(
+    !/hint_share \/ placement_share/.test(terraform),
+    'cross-multiply instead: hint_share > 2 * placement_share'
+  )
+  assert.match(collapse(terraform), /condition hint_share > 2 \* placement_share/)
+})
+
 test('the unhinted bucket stays out of the skew denominators', () => {
   assert.ok(
     !terraformRegions.includes('unhinted'),
diff --git a/cloud/docs/relay-incident-monitor.md b/cloud/docs/relay-incident-monitor.md
index 8d0b93c03e5..696efb85296 100644
--- a/cloud/docs/relay-incident-monitor.md
+++ b/cloud/docs/relay-incident-monitor.md
@@ -161,7 +161,11 @@ Threshold basis:
   the broken state and outside a healthy one. `unhinted` requests are
   excluded from the denominator: they were 27% of all requests, so a client
   change that always sends a hint would move the number with no behaviour
-  change at all.
+  change at all. The two bars are cross-multiplied rather than divided. An
+  hour that placed nobody in the region is the most extreme skew there is,
+  and it happens whenever the region is drained, fenced, or at capacity, but
+  dividing by that zero placement share makes MQL drop the row and lose the
+  series before any other clause runs.
 
 Expect the skew alert to stay lit after a client fix until the mis-homed
 backlog is rehomed. Sticky assignment never re-consults the hint, so a
@@ -185,7 +189,10 @@ every interval, not the nested region maps: a log-based metric would need a
 quoted field path to reach a hyphenated map key, and an absent key would drop
 a series out of the inner join. The region list lives in Terraform as
 `relay_region_keys` and is pinned to relay-contract's `RELAY_REGIONS` by
-`dev/scripts/relay-region-hint-metrics.test.mjs`.
+`dev/scripts/relay-region-hint-metrics.test.mjs`. Both sides spell the field
+name segments out as literal maps rather than deriving them, so the same test
+compares the two declarations directly. Adding a region to the contract
+without its segment is a compile error in relay-contract, not a silent gap.
 
 ## Implementation log
 
diff --git a/cloud/infra/terraform/relay-observability.tf b/cloud/infra/terraform/relay-observability.tf
index 83fbb9c960e..4c6722d3532 100644
--- a/cloud/infra/terraform/relay-observability.tf
+++ b/cloud/infra/terraform/relay-observability.tf
@@ -100,10 +100,12 @@ locals {
   relay_region_keys = ["us-central1", "asia-east2"]
   # Flat emitter fields, not the nested `requestedRegionsDelta` map: a log-based metric would need
   # a quoted field path to reach a hyphenated map key, and the relay publishes these as zeros in
-  # every interval so no series can drop out of the alert's inner join.
+  # every interval so no series can drop out of the alert's inner join. Spelled out rather than
+  # derived, so this literal and relay-contract's RELAY_REGION_METRIC_SEGMENTS can be compared
+  # directly; reformatting either side cannot break the check and neither can drift alone.
   relay_region_field_segments = {
-    for key in local.relay_region_keys :
-    key => join("", [for part in split("-", key) : title(part)])
+    "us-central1" = "UsCentral1"
+    "asia-east2"  = "AsiaEast2"
   }
   relay_region_columns = { for key in local.relay_region_keys : key => replace(key, "-", "_") }
   relay_region_share_metrics = merge(
@@ -155,12 +157,14 @@ locals {
       "    placement_share: sel_asia_east2 / (${local.relay_region_selected_total}),",
       "    hinted_requests: ${local.relay_region_hinted_total}",
       "  ]",
-      "| value [",
-      "    divergence: hint_share / placement_share,",
-      "    gap: hint_share - placement_share,",
-      "    hinted_requests: hinted_requests",
-      "  ]",
-      "| condition divergence > 2 '1' && gap > 0.15 '1' && hinted_requests > 500 '1'"
+      # Cross-multiplied, never a plain ratio of the two shares: an hour that placed nobody in the
+      # region makes that ratio 0/0 or x/0, and MQL drops the row instead of yielding a number, so
+      # the whole series vanishes before the other clauses run. That hour is the worst skew there
+      # is - every desktop asking for a region the director is putting nobody in - and it happens
+      # whenever the region is drained, fenced, or at capacity. Both forms were run read-only
+      # against production surrogates with a zero denominator: the ratio returned no rows, this
+      # returned the series with the condition true.
+      "| condition hint_share > 2 * placement_share && hint_share - placement_share > 0.15 '1' && hinted_requests > 500 '1'"
     ]
   ))
   relay_custom_alerts = {
diff --git a/cloud/packages/relay-contract/src/relay-regions.ts b/cloud/packages/relay-contract/src/relay-regions.ts
index 38ac36cd738..6b8837829df 100644
--- a/cloud/packages/relay-contract/src/relay-regions.ts
+++ b/cloud/packages/relay-contract/src/relay-regions.ts
@@ -8,6 +8,15 @@ export type RelayRegion = z.infer<typeof RelayRegionSchema>
 
 export const RELAY_DEFAULT_REGION: RelayRegion = 'us-central1'
 
+// Field-name segment for the flat per-region runtime counters, spelled out rather than derived so
+// the Terraform side can hold the same literal and a test can compare the two. `satisfies` makes a
+// new region a compile error here, which is the point: a region with no segment would silently
+// drop out of the region-skew alert's denominators.
+export const RELAY_REGION_METRIC_SEGMENTS = {
+  'us-central1': 'UsCentral1',
+  'asia-east2': 'AsiaEast2'
+} as const satisfies Record<RelayRegion, string>
+
 const RelayProbeOriginSchema = z.string().url().max(2_048).refine(isCanonicalHttpsOrigin)
 
 export const RelayRegionCatalogResponseSchema = z