job-hunter: weekly above-target Slack alert CronJob

Add job-hunter-alert CronJob (Sundays 05:00 UTC, an hour after the refresh):
`python -m job_hunter alert --threshold 500000 --location london --slack`
posts to Slack the companies whose London p50 total comp >= £500k, flagging
any that newly crossed since last week's snapshot. SLACK_WEBHOOK_URL wired via
the job-hunter-secrets ExternalSecret from Vault secret/job-hunter
slack_webhook_url (seeded from the shared workspace webhook; repointable to a
dedicated channel). Runbook gains an "above-target Slack alert" section.

[ci skip] — applied locally (stack-scoped).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/runbooks/job-hunter.md

@@ -164,6 +164,31 @@ Grafana datasource password is mirrored via a second ExternalSecret in the
 
 ## ANALYST
 
+### Weekly above-target Slack alert
+
+The `job-hunter-alert` CronJob (Sundays 05:00 UTC, an hour after the refresh)
+posts to Slack the companies whose London p50 total comp **≥ £500k**, flagging
+any that **newly crossed** since last week's snapshot. Threshold is the
+`--threshold` arg in `cronjob.tf` (default 500000 — well above the ~£267k move
+floor, so only clearly-exceptional comp pings). Slack webhook comes from Vault
+`secret/job-hunter` → `slack_webhook_url` (seeded from the shared workspace
+webhook → currently posts to the same channel as Keel; repoint to a dedicated
+channel by `vault kv patch secret/job-hunter slack_webhook_url=<url>`).
+
+```bash
+# Preview the message without posting
+kubectl -n job-hunter exec deploy/job-hunter -- python -m job_hunter alert --stdout
+# Different bar / location
+kubectl -n job-hunter exec deploy/job-hunter -- \
+  python -m job_hunter alert --threshold 350000 --location london --stdout
+# Fire it now (posts to Slack)
+kubectl -n job-hunter create job --from=cronjob/job-hunter-alert jh-alert-manual
+```
+
+`newly_crossed` needs ≥2 snapshot dates — it's empty until the second weekly
+run accumulates. To change the standing threshold, edit `--threshold` in
+`infra/stacks/job-hunter/cronjob.tf` and apply.
+
 ### The periodic "market leaders in comp" report
 
 This is the headline command — current leaders by p50 total comp, week-over-week

stacks/job-hunter/cronjob.tf

@@ -111,3 +111,83 @@ resource "kubernetes_cron_job_v1" "job_hunter_refresh" {
     kubernetes_manifest.db_external_secret,
   ]
 }
+
+# Weekly above-target comp alert. Runs an hour after the refresh (so it reads
+# fresh data + the just-written snapshot) and posts to Slack the companies whose
+# London p50 total comp >= £500k, flagging any that newly crossed since last
+# week's snapshot. Read-only query + a Slack POST — no init/migrate needed.
+resource "kubernetes_cron_job_v1" "job_hunter_alert" {
+  metadata {
+    name      = "job-hunter-alert"
+    namespace = kubernetes_namespace.job_hunter.metadata[0].name
+    labels    = local.labels
+  }
+  spec {
+    schedule                      = "0 5 * * 0"
+    concurrency_policy            = "Forbid"
+    successful_jobs_history_limit = 3
+    failed_jobs_history_limit     = 3
+    starting_deadline_seconds     = 600
+
+    job_template {
+      metadata {
+        labels = local.labels
+      }
+      spec {
+        backoff_limit              = 2
+        active_deadline_seconds    = 300
+        ttl_seconds_after_finished = 86400
+
+        template {
+          metadata {
+            labels = local.labels
+          }
+          spec {
+            restart_policy = "OnFailure"
+            image_pull_secrets {
+              name = "registry-credentials"
+            }
+            container {
+              name              = "alert"
+              image             = local.image
+              image_pull_policy = "Always"
+              command = ["python", "-m", "job_hunter", "alert",
+              "--threshold", "500000", "--location", "london", "--slack"]
+
+              env_from {
+                secret_ref {
+                  name = "job-hunter-secrets"
+                }
+              }
+              env_from {
+                secret_ref {
+                  name = "job-hunter-db-creds"
+                }
+              }
+
+              resources {
+                requests = {
+                  cpu    = "50m"
+                  memory = "256Mi"
+                }
+                limits = {
+                  memory = "512Mi"
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+
+  lifecycle {
+    # KYVERNO_LIFECYCLE_V1
+    ignore_changes = [spec[0].job_template[0].spec[0].template[0].spec[0].dns_config]
+  }
+
+  depends_on = [
+    kubernetes_manifest.external_secret,
+    kubernetes_manifest.db_external_secret,
+  ]
+}

stacks/job-hunter/main.tf

@@ -89,6 +89,13 @@ resource "kubernetes_manifest" "external_secret" {
           secretKey = "DIGEST_FROM_ADDRESS"
           remoteRef = { key = "job-hunter", property = "digest_from_address" }
         },
+        {
+          # Weekly above-target comp alert (job-hunter-alert CronJob). Seeded
+          # from the shared workspace webhook; repoint to a dedicated channel
+          # by updating secret/job-hunter slack_webhook_url.
+          secretKey = "SLACK_WEBHOOK_URL"
+          remoteRef = { key = "job-hunter", property = "slack_webhook_url" }
+        },
       ]
     }
   }