fix(ingestion): drop always-NULL class_people.org_unit_id column

src/ingestion/connectors/hr-directory/active-directory/dbt/active_directory__to_class_people.sql

@@ -32,8 +32,12 @@ SELECT
     -- Prefer `mail` as canonical address; fall back to UPN when mail unset.
     coalesce(u.mail, u.userPrincipalName)           AS email,
     u.jobTitle                                      AS job_title,
+    -- `department_name` is the org cohort key for this class. There is no
+    -- org-unit UUID anywhere in the system (no `org_units` table exists), so
+    -- the former always-NULL `org_unit_id Nullable(UUID)` column was dropped.
+    -- Downstream `org_unit_id` (insight.people, gold views, the frontend) is a
+    -- department NAME string derived from this field.
     u.department                                    AS department_name,
-    CAST(NULL AS Nullable(UUID))                    AS org_unit_id,
     -- manager_person_id is the resolved unified person ID, not an AD source ID.
     -- Leave it null here; Silver Step 2 (Identity Manager) resolves it from the
     -- parent_id/parent_email identity_inputs signals emitted by

src/ingestion/connectors/hr-directory/bamboohr/dbt/bamboohr__to_class_people.sql

@@ -30,8 +30,12 @@ SELECT
     lastName                                        AS last_name,
     workEmail                                       AS email,
     jobTitle                                        AS job_title,
+    -- `department_name` is the org cohort key for this class. There is no
+    -- org-unit UUID anywhere in the system (no `org_units` table exists), so
+    -- the former always-NULL `org_unit_id Nullable(UUID)` column was dropped.
+    -- Downstream `org_unit_id` (insight.people, gold views, the frontend) is a
+    -- department NAME string derived from this field.
     department                                      AS department_name,
-    CAST(NULL AS Nullable(UUID))                    AS org_unit_id,
     supervisorEId                                   AS manager_person_id,
     CASE
         WHEN status = 'Active' THEN 'active'

src/ingestion/connectors/hr-directory/ms-entra/dbt/ms_entra__to_class_people.sql

@@ -33,8 +33,12 @@ SELECT
     -- (common for guest/external users).
     coalesce(mail, userPrincipalName)               AS email,
     jobTitle                                        AS job_title,
+    -- `department_name` is the org cohort key for this class. There is no
+    -- org-unit UUID anywhere in the system (no `org_units` table exists), so
+    -- the former always-NULL `org_unit_id Nullable(UUID)` column was dropped.
+    -- Downstream `org_unit_id` (insight.people, gold views, the frontend) is a
+    -- department NAME string derived from this field.
     department                                      AS department_name,
-    CAST(NULL AS Nullable(UUID))                    AS org_unit_id,
     -- Manager relationships are not collected in v1 of the connector;
     -- a future iteration will add `$expand=manager` to populate this.
     CAST(NULL AS Nullable(String))                  AS manager_person_id,

src/ingestion/connectors/hr-directory/workday/dbt/workday__to_class_people.sql

@@ -32,8 +32,12 @@ SELECT
     Business_Title                                           AS job_title,
     -- Workday has no freeform department; the supervisory organization is the
     -- standard org unit every tenant is guaranteed to have.
+    -- `department_name` is the org cohort key for this class. There is no
+    -- org-unit UUID anywhere in the system (no `org_units` table exists), so
+    -- the former always-NULL `org_unit_id Nullable(UUID)` column was dropped.
+    -- Downstream `org_unit_id` (insight.people, gold views, the frontend) is a
+    -- department NAME string derived from this field.
     Supervisory_Organization                                 AS department_name,
-    CAST(NULL AS Nullable(UUID))                             AS org_unit_id,
     Manager_Employee_ID                                      AS manager_person_id,
     multiIf(
         Worker_Status = 'Terminated', 'terminated',

src/ingestion/gold/metric_entity_cohorts_current.sql

@@ -21,10 +21,17 @@ FROM (
     SELECT
         workspace_id AS tenant_id,
         lower(assumeNotNull(email)) AS entity_id,
-        coalesce(
-            nullIf(toString(org_unit_id), ''),
-            nullIf(department_name, '')
-        ) AS cohort_id
+        -- The org cohort is keyed by department NAME, matching what the rest of
+        -- the serving path calls `org_unit_id` (insight.people projects
+        -- `argMax(department)` under that name, and the frontend round-trips the
+        -- value back as `org_unit_id in ('Engineering', …)`). This used to
+        -- coalesce a `class_people.org_unit_id Nullable(UUID)` column ahead of
+        -- the name; that column was always NULL (no `org_units` table exists) and
+        -- has been dropped. Do NOT reintroduce a UUID branch here without
+        -- migrating insight.people and the frontend in the same change — a
+        -- coalesce that prefers UUIDs would emit cohort ids the frontend never
+        -- sends, silently emptying every peer metric.
+        nullIf(department_name, '') AS cohort_id
     FROM {{ ref('class_people') }}
     WHERE email IS NOT NULL
       AND email != ''

src/ingestion/scripts/connectors-ddl/insight.sql

@@ -2726,7 +2726,7 @@ FROM
     SELECT
         workspace_id AS tenant_id,
         lower(assumeNotNull(email)) AS entity_id,
-        coalesce(nullIf(toString(org_unit_id), ''), nullIf(department_name, '')) AS cohort_id
+        nullIf(department_name, '') AS cohort_id
     FROM silver.class_people
     WHERE (email IS NOT NULL) AND (email != '') AND (workspace_id IS NOT NULL) AND (workspace_id != '')
     ORDER BY

src/ingestion/scripts/connectors-ddl/silver.sql

@@ -642,7 +642,6 @@ CREATE TABLE IF NOT EXISTS silver.class_people
     `email` Nullable(String),
     `job_title` Nullable(String),
     `department_name` Nullable(String),
-    `org_unit_id` Nullable(UUID),
     `manager_person_id` Nullable(String),
     `status` String,
     `employment_type` String,