refactor: model repository metrics and releases as facts

dbt/models/marts/_marts__models.yml

@@ -147,6 +147,31 @@ models:
               arguments:
                 expression: ">= 0"
 
+  - name: fct_releases
+    description: >
+      One row per published release. Repository resolved via the SCD2 half-open range
+      on the publish date. Incremental (delete+insert on release_key). An event fact
+      analyzed by counting (release cadence), with no additive measure.
+    columns:
+      - name: release_key
+        description: Surrogate key, hash of repository + release_id.
+        data_tests: [not_null, unique]
+      - name: repository_key
+        data_tests:
+          - not_null
+          - relationships:
+              arguments:
+                to: ref('dim_repositories')
+                field: repository_key
+      - name: date_key
+        description: FK to dim_dates (publish day, YYYYMMDD).
+        data_tests:
+          - not_null
+          - relationships:
+              arguments:
+                to: ref('dim_dates')
+                field: date_key
+
   - name: bridge_issue_labels
     description: Bridge for the issue<->label many-to-many. Grain - one row per issue/label.
     data_tests:
@@ -203,6 +228,50 @@ models:
               arguments:
                 expression: ">= 0"
 
+  - name: fct_repository_metrics
+    description: >
+      Periodic-snapshot fact: one row per repository per capture (ingestion) day,
+      recording GitHub stars/forks/open_issues. Accumulated incrementally
+      (delete+insert on metric_key).
+    columns:
+      - name: metric_key
+        description: Surrogate key, hash of repository_id + capture date.
+        data_tests: [not_null, unique]
+      - name: repository_key
+        description: FK to dim_repositories (version current on the capture date).
+        data_tests:
+          - not_null
+          - relationships:
+              arguments:
+                to: ref('dim_repositories')
+                field: repository_key
+      - name: date_key
+        description: FK to dim_dates (capture day, YYYYMMDD).
+        data_tests:
+          - not_null
+          - relationships:
+              arguments:
+                to: ref('dim_dates')
+                field: date_key
+      - name: stars
+        description: Stargazer count at capture time.
+        data_tests:
+          - dbt_utils.expression_is_true:
+              arguments:
+                expression: ">= 0"
+      - name: forks
+        description: Fork count at capture time.
+        data_tests:
+          - dbt_utils.expression_is_true:
+              arguments:
+                expression: ">= 0"
+      - name: open_issues
+        description: Open issue (+PR) count at capture time.
+        data_tests:
+          - dbt_utils.expression_is_true:
+              arguments:
+                expression: ">= 0"
+
   - name: fct_contributor_activity_monthly
     description: >
       Aggregate fact, one row per contributor per month, pivoting the activity event

dbt/models/marts/dim_repositories.sql

@@ -9,9 +9,6 @@ with versioned as (
         name,
         owner_login,
         description,
-        stars,
-        forks,
-        open_issues,
         language,
         license_spdx,
         topics,
@@ -43,9 +40,6 @@ select
     name,
     owner_login,
     description,
-    stars,
-    forks,
-    open_issues,
     language,
     license_spdx,
     topics,

dbt/models/marts/fct_releases.sql

@@ -0,0 +1,37 @@
+-- Release activity fact: one row per published release. Joins to dim_repositories via
+-- the SCD2 half-open date range (event_date >= valid_from AND < valid_to) so each
+-- release maps to the repository version current when it was published; to dim_dates
+-- via an inline YYYYMMDD key on the publish date. An event fact with no additive
+-- measure - analyze by counting (release cadence, time between releases).
+-- Incremental (delete+insert on release_key) keyed on the monotonic dlt `_loaded_at`
+-- (publish dates can be backdated); the unique key keeps it idempotent.
+
+{{
+    config(
+        materialized='incremental',
+        unique_key='release_key',
+        incremental_strategy='delete+insert',
+        on_schema_change='sync_all_columns',
+    )
+}}
+
+with releases as (
+    select * from {{ ref('stg_github__releases') }}
+    -- Drafts have no publish date; exclude them so date_key / repository_key resolve.
+    where published_at is not null
+    {% if is_incremental() %}
+    and _loaded_at >= (select max(_loaded_at) from {{ this }})
+    {% endif %}
+)
+
+select
+    {{ dbt_utils.generate_surrogate_key(['rel.repository', 'rel.release_id']) }}
+        as release_key,
+    r.repository_key,
+    {{ date_key('rel.published_at') }} as date_key,
+    rel.tag_name,
+    rel.name as release_name,
+    rel.published_at,
+    rel._loaded_at
+from releases rel
+{{ scd2_repository_join('rel.repository', 'rel.published_at::date') }}

dbt/models/marts/fct_repository_metrics.sql

@@ -0,0 +1,40 @@
+-- GitHub repository metrics fact: a periodic-snapshot fact at one row per repository
+-- per capture (ingestion) day, recording the volatile counters stars/forks/open_issues.
+-- GitHub's API returns only the *current* counter values (no history), so history is
+-- accumulated incrementally - each daily run appends that day's values, dated by the
+-- dlt load timestamp. `repository_key` resolves through the SCD2 dim_repositories
+-- half-open range for the capture date. Incremental (delete+insert on metric_key)
+-- keeps same-day re-runs idempotent.
+
+{{
+    config(
+        materialized='incremental',
+        unique_key='metric_key',
+        incremental_strategy='delete+insert',
+        on_schema_change='sync_all_columns',
+    )
+}}
+
+with repositories as (
+    select
+        *,
+        cast(_loaded_at as date) as capture_date
+    from {{ ref('stg_github__repositories') }}
+    {% if is_incremental() %}
+    -- Only (re)load capture days at or after the latest already loaded.
+    where {{ date_key('_loaded_at') }} >= (select max(date_key) from {{ this }})
+    {% endif %}
+)
+
+select
+    {{ dbt_utils.generate_surrogate_key(['m.repository_id', 'm.capture_date']) }}
+        as metric_key,
+    m.repository_id,
+    m.repository_name,
+    r.repository_key,
+    {{ date_key('m.capture_date') }} as date_key,
+    m.stars,
+    m.forks,
+    m.open_issues
+from repositories m
+{{ scd2_repository_join('m.repository_name', 'm.capture_date') }}

dbt/snapshots/snap_repositories.sql

@@ -4,7 +4,7 @@
     config(
         unique_key='repository_id',
         strategy='check',
-        check_cols=['stars', 'forks', 'open_issues', 'description', 'topics'],
+        check_cols=['description', 'language', 'license_spdx', 'topics'],
     )
 }}