diff --git a/backend/src/__tests__/git-source-routes.test.ts b/backend/src/__tests__/git-source-routes.test.ts
index b160c431..b2ab015a 100644
--- a/backend/src/__tests__/git-source-routes.test.ts
+++ b/backend/src/__tests__/git-source-routes.test.ts
@@ -2412,6 +2412,80 @@ describe('git-source policy compatibility', () => {
         }
     });
 
+    it('PUT on an existing source with explicit source_policy persists the resolved policy', async () => {
+        const stackName = 'policy-put-existing-review';
+        seedStackDir(stackName);
+        seedGitSource(stackName);
+        seedApp(stackName, 'automatic');
+        const fetchFromGit = stubFetchFromGit();
+        try {
+            const res = await request(app)
+                .put(`/api/stacks/${stackName}/git-source`)
+                .set('Authorization', `Bearer ${adminToken()}`)
+                .send(putBody({ auto_apply_on_webhook: false, source_policy: 'review' }));
+            expect(res.status).toBe(200);
+            // The stored row carries the new policy, not just the response.
+            const application = GitOpsStore.getInstance().getLiveDirectApplication(stackName);
+            expect(application?.source_policy).toBe('review');
+            // The projection flips with it: review never auto-applies.
+            expect(res.body.auto_apply_on_webhook).toBe(false);
+            const after = await request(app)
+                .get(`/api/stacks/${stackName}/git-source`)
+                .set('Authorization', `Bearer ${adminToken()}`);
+            expect(after.body.auto_apply_on_webhook).toBe(false);
+        } finally {
+            fetchFromGit.mockRestore();
+            deleteRows(stackName);
+        }
+    });
+
+    it('PUT on an existing source with auto_apply_on_webhook true upgrades review to automatic', async () => {
+        const stackName = 'policy-put-existing-automatic';
+        seedStackDir(stackName);
+        seedGitSource(stackName);
+        seedApp(stackName, 'review');
+        const fetchFromGit = stubFetchFromGit();
+        try {
+            const res = await request(app)
+                .put(`/api/stacks/${stackName}/git-source`)
+                .set('Authorization', `Bearer ${adminToken()}`)
+                .send(putBody({ auto_apply_on_webhook: true }));
+            expect(res.status).toBe(200);
+            const application = GitOpsStore.getInstance().getLiveDirectApplication(stackName);
+            expect(application?.source_policy).toBe('automatic');
+            expect(res.body.auto_apply_on_webhook).toBe(true);
+        } finally {
+            fetchFromGit.mockRestore();
+            deleteRows(stackName);
+        }
+    });
+
+    it.each([
+        ['false', false],
+        ['omitted', undefined],
+    ])('PUT on an existing automatic source with %s auto_apply_on_webhook stays automatic', async (_name, flag) => {
+        const stackName = `policy-put-existing-keeps-auto-${_name}`;
+        seedStackDir(stackName);
+        seedGitSource(stackName);
+        seedApp(stackName, 'automatic');
+        const fetchFromGit = stubFetchFromGit();
+        try {
+            const res = await request(app)
+                .put(`/api/stacks/${stackName}/git-source`)
+                .set('Authorization', `Bearer ${adminToken()}`)
+                .send(putBody({ auto_apply_on_webhook: flag }));
+            expect(res.status).toBe(200);
+            // Boolean 0 or absent must not silently convert an existing
+            // automatic policy; the operator has to ask explicitly.
+            const application = GitOpsStore.getInstance().getLiveDirectApplication(stackName);
+            expect(application?.source_policy).toBe('automatic');
+            expect(res.body.auto_apply_on_webhook).toBe(true);
+        } finally {
+            fetchFromGit.mockRestore();
+            deleteRows(stackName);
+        }
+    });
+
     it('explicit source_policy wins over the boolean', async () => {
         const stackName = 'policy-explicit-wins';
         seedStackDir(stackName);
diff --git a/backend/src/services/GitSourceService.ts b/backend/src/services/GitSourceService.ts
index 1dbae804..f490af1f 100644
--- a/backend/src/services/GitSourceService.ts
+++ b/backend/src/services/GitSourceService.ts
@@ -983,6 +983,15 @@ export class GitSourceService {
                     envelope,
                 });
             }
+            // A policy change on an existing application persists durably: the
+            // create path stamps the policy through activateDirect, and this is
+            // the existing-app counterpart, so explicit PUT policy edits (and
+            // boolean-true upgrades) survive the save. A boolean 0 or absent
+            // resolves to the existing policy here and never silently converts
+            // it.
+            if (app && app.source_policy !== effectivePolicy) {
+                GitOpsTransitions.getInstance().sourcePolicyChanged(app.id, effectivePolicy, envelope);
+            }
         })();
 
         if (
diff --git a/backend/src/services/gitops/history.ts b/backend/src/services/gitops/history.ts
index f7e8a5b3..6318d6f7 100644
--- a/backend/src/services/gitops/history.ts
+++ b/backend/src/services/gitops/history.ts
@@ -71,6 +71,7 @@ export type GitOpsHistoryStage =
   | 'source_accepted'
   | 'source_conflict_blocker'
   | 'source_poll_scheduled'
+  | 'source_policy_changed'
   | 'source_reconcile_started'
   | 'source_reconcile_settled'
   | 'source_retry_scheduled'
diff --git a/backend/src/services/gitops/transitions.ts b/backend/src/services/gitops/transitions.ts
index 8decfc39..db95200d 100644
--- a/backend/src/services/gitops/transitions.ts
+++ b/backend/src/services/gitops/transitions.ts
@@ -20,6 +20,7 @@ import type {
   GitOpsIntentRevisionRow,
   GitOpsRolloutCandidateRow,
   GitOpsTargetCurrentRow,
+  SourcePolicy,
 } from './types';
 
 export type EventEnvelope = {
@@ -894,6 +895,23 @@ export class GitOpsTransitions {
     });
   }
 
+  /**
+   * Persist a resolved source policy onto a live application. The create path
+   * stamps the policy through activateDirect; this is the existing-app path,
+   * so an operator who changes the policy on an already-linked source gets a
+   * durable row change (and an audit line) instead of a silently discarded
+   * PUT field.
+   */
+  sourcePolicyChanged(applicationId: string, sourcePolicy: SourcePolicy, envelope: EventEnvelope): TransitionResult {
+    return this.mutateApp(applicationId, envelope, 'source_policy_changed', 'committed', (app) => {
+      if (app.suspended_at) throw new GitOpsTransitionError('source is suspended');
+      if (app.active_operation_stage) {
+        throw new GitOpsTransitionError('cannot change the source policy while an operation is in flight');
+      }
+      app.source_policy = sourcePolicy;
+    });
+  }
+
   /**
    * Stop acting on a source without forgetting anything about it.
    *