diff --git a/packages/spacecat-shared-data-access/src/models/geo-experiment/geo-experiment.model.js b/packages/spacecat-shared-data-access/src/models/geo-experiment/geo-experiment.model.js
index 1dcd07168..36b11ba61 100644
--- a/packages/spacecat-shared-data-access/src/models/geo-experiment/geo-experiment.model.js
+++ b/packages/spacecat-shared-data-access/src/models/geo-experiment/geo-experiment.model.js
@@ -22,6 +22,7 @@ class GeoExperiment extends BaseModel {
 
   static TYPES = {
     ONSITE_OPPORTUNITY_DEPLOYMENT: 'onsite_opportunity_deployment',
+    OPTIMIZE_AT_SOURCE: 'optimize_at_source',
   };
 
   static STATUSES = {
@@ -47,6 +48,14 @@ class GeoExperiment extends BaseModel {
     POST_ANALYSIS_DONE: 'post_analysis_done',
     IMPACT_MEASUREMENT_STARTED: 'impact_measurement_started',
     IMPACT_MEASUREMENT_DONE: 'impact_measurement_done',
+    // optimize-at-source (OAS) strategy phases
+    OAS_INITIATED: 'oas_initiated',
+    OAS_BASELINE_STARTED: 'oas_baseline_started',
+    OAS_BASELINE_DONE: 'oas_baseline_done',
+    OAS_AWAITING_PUBLISH: 'oas_awaiting_publish',
+    OAS_PUBLISH_VERIFIED: 'oas_publish_verified',
+    OAS_POST_SNAPSHOT: 'oas_post_snapshot',
+    OAS_COMPLETED: 'oas_completed',
   };
 
   /**
@@ -83,6 +92,15 @@ class GeoExperiment extends BaseModel {
     OAE_VALIDATION_JOBS: 'oaeValidationJobs',
     // Baseline (window 0) measurement bookkeeping, e.g. { taskId, startedAt, retryCount }.
     BASELINE_MEASUREMENT: 'baselineMeasurement',
+    // optimize-at-source bookkeeping.
+    // URLs the external UI deployed, to be publish-checked, e.g. ['https://example.com/a'].
+    DEPLOYED_URLS: 'deployedUrls',
+    // Publish-check progress, e.g. { verifiedUrls: [...], lastCheckedAt }.
+    PUBLISH_CHECK: 'publishCheck',
+    // 14-day post window bookkeeping, e.g. { startedAt, lastSnapshotAt, snapshotCount }.
+    POST_WINDOW: 'postWindow',
+    // S3 location (key) of the raw daily SEO-metric snapshots.
+    SNAPSHOTS_LOCATION: 'snapshotsLocation',
   };
 
   /**
diff --git a/packages/spacecat-shared-data-access/test/unit/models/geo-experiment/geo-experiment.model.test.js b/packages/spacecat-shared-data-access/test/unit/models/geo-experiment/geo-experiment.model.test.js
index edbb61e5a..101ca4756 100644
--- a/packages/spacecat-shared-data-access/test/unit/models/geo-experiment/geo-experiment.model.test.js
+++ b/packages/spacecat-shared-data-access/test/unit/models/geo-experiment/geo-experiment.model.test.js
@@ -83,9 +83,31 @@ describe('GeoExperimentModel', () => {
       ROUTING_VALIDATION: 'routingValidation',
       OAE_VALIDATION_JOBS: 'oaeValidationJobs',
       BASELINE_MEASUREMENT: 'baselineMeasurement',
+      DEPLOYED_URLS: 'deployedUrls',
+      PUBLISH_CHECK: 'publishCheck',
+      POST_WINDOW: 'postWindow',
+      SNAPSHOTS_LOCATION: 'snapshotsLocation',
     });
   });
 
+  it('exposes the optimize-at-source experiment type', () => {
+    expect(GeoExperiment.TYPES.OPTIMIZE_AT_SOURCE).to.equal('optimize_at_source');
+  });
+
+  it('exposes the optimize-at-source phases, in lifecycle order', () => {
+    const oasPhases = Object.entries(GeoExperiment.PHASES)
+      .filter(([key]) => key.startsWith('OAS_'));
+    expect(oasPhases).to.deep.equal([
+      ['OAS_INITIATED', 'oas_initiated'],
+      ['OAS_BASELINE_STARTED', 'oas_baseline_started'],
+      ['OAS_BASELINE_DONE', 'oas_baseline_done'],
+      ['OAS_AWAITING_PUBLISH', 'oas_awaiting_publish'],
+      ['OAS_PUBLISH_VERIFIED', 'oas_publish_verified'],
+      ['OAS_POST_SNAPSHOT', 'oas_post_snapshot'],
+      ['OAS_COMPLETED', 'oas_completed'],
+    ]);
+  });
+
   it('exposes SCHEDULE_CONFIG_KEYS constant', () => {
     expect(GeoExperiment.SCHEDULE_CONFIG_KEYS).to.deep.equal({
       CRON_EXPRESSION: 'cronExpression',