diff --git a/.github/workflows/agentic-auto-upgrade.yml b/.github/workflows/agentic-auto-upgrade.yml
index 7035101ee35..6aff9d33647 100644
--- a/.github/workflows/agentic-auto-upgrade.yml
+++ b/.github/workflows/agentic-auto-upgrade.yml
@@ -34,7 +34,7 @@ name: Agentic Auto-Upgrade
 
 on:
   schedule:
-    - cron: "21 3 * * 5"  # Weekly (auto-upgrade)
+    - cron: "41 23 * * 1"  # Weekly (auto-upgrade)
   workflow_dispatch:
 
 permissions:
diff --git a/pkg/workflow/auto_update_workflow.go b/pkg/workflow/auto_update_workflow.go
index 18e0949f925..77c340137c5 100644
--- a/pkg/workflow/auto_update_workflow.go
+++ b/pkg/workflow/auto_update_workflow.go
@@ -78,7 +78,12 @@ func GenerateAutoUpdateWorkflow(opts GenerateAutoUpdateWorkflowOptions) error {
 		return nil
 	}
 
-	seed := buildAutoUpdateSeed(opts.RepoSlug)
+	actionMode := opts.ActionMode
+	if actionMode == "" {
+		actionMode = DetectActionMode(opts.Version)
+	}
+
+	seed := buildAutoUpdateSeed(opts.RepoSlug, actionMode)
 	cronSchedule, err := parser.ScatterSchedule("FUZZY:WEEKLY", seed)
 	if err != nil {
 		return fmt.Errorf("failed to scatter FUZZY:WEEKLY schedule for auto-update workflow: %w", err)
@@ -94,10 +99,6 @@ func GenerateAutoUpdateWorkflow(opts GenerateAutoUpdateWorkflowOptions) error {
 		githubScriptPin = getActionPin("actions/github-script")
 	}
 
-	actionMode := opts.ActionMode
-	if actionMode == "" {
-		actionMode = ActionModeDev
-	}
 	ctx := opts.Context
 	if ctx == nil {
 		ctx = context.Background()
@@ -123,9 +124,24 @@ func GenerateAutoUpdateWorkflow(opts GenerateAutoUpdateWorkflowOptions) error {
 }
 
 // buildAutoUpdateSeed returns the deterministic seed string used to scatter the
-// FUZZY:WEEKLY cron schedule. It combines the repo slug with the fixed workflow
-// identifier so that repositories scatter to distinct time slots.
-func buildAutoUpdateSeed(repoSlug string) string {
+// FUZZY:WEEKLY cron schedule.
+//
+// In dev mode a stable "dev/" prefix is used instead of the slug, which may not
+// be available (e.g. in sandbox environments where the git remote URL is a
+// localhost proxy). This mirrors the behaviour of normalizeScheduleString in
+// schedule_preprocessing.go and prevents the generated schedule from changing
+// between dev builds when --schedule-seed is sometimes provided and sometimes not.
+//
+// In all other modes (release, action, script) the repo slug is incorporated so
+// that different repositories scatter to distinct time slots. Note: released
+// binaries auto-detect ActionModeAction, not ActionModeRelease, so checking only
+// IsRelease() would cause ActionModeAction builds to silently use the dev seed.
+func buildAutoUpdateSeed(repoSlug string, actionMode ActionMode) string {
+	if actionMode.IsDev() {
+		// Dev mode: use a fixed prefix that does not depend on git remote detection.
+		return "dev/" + autoUpdateWorkflowIdentifier
+	}
+	// Release/action/script mode: incorporate repo slug for per-repo scattering.
 	if repoSlug != "" {
 		return repoSlug + "/" + autoUpdateWorkflowIdentifier
 	}
diff --git a/pkg/workflow/auto_update_workflow_test.go b/pkg/workflow/auto_update_workflow_test.go
index 60447fe1e8c..2773ca75fb1 100644
--- a/pkg/workflow/auto_update_workflow_test.go
+++ b/pkg/workflow/auto_update_workflow_test.go
@@ -102,15 +102,19 @@ func TestGenerateAutoUpdateWorkflow_DifferentReposDifferentCron(t *testing.T) {
 	dir1 := t.TempDir()
 	dir2 := t.TempDir()
 
+	// Per-repo schedule scattering applies in all non-dev modes.
+	// Use ActionModeAction since that is what released binaries actually detect.
 	require.NoError(t, GenerateAutoUpdateWorkflow(GenerateAutoUpdateWorkflowOptions{
 		WorkflowDir: dir1,
 		Enabled:     true,
 		RepoSlug:    "org1/repo-alpha",
+		ActionMode:  ActionModeAction,
 	}))
 	require.NoError(t, GenerateAutoUpdateWorkflow(GenerateAutoUpdateWorkflowOptions{
 		WorkflowDir: dir2,
 		Enabled:     true,
 		RepoSlug:    "org2/repo-beta",
+		ActionMode:  ActionModeAction,
 	}))
 
 	data1, err := os.ReadFile(filepath.Join(dir1, AutoUpdateWorkflowFileName))
@@ -125,7 +129,7 @@ func TestGenerateAutoUpdateWorkflow_DifferentReposDifferentCron(t *testing.T) {
 	assert.NotEmpty(t, cron2, "cron should be non-empty for org2/repo-beta")
 	// Schedules are scattered by hash — different repos should typically differ.
 	// This is a best-effort check; hash collisions are possible but unlikely for these slugs.
-	assert.NotEqual(t, cron1, cron2, "different repo slugs should produce different cron schedules")
+	assert.NotEqual(t, cron1, cron2, "different repo slugs should produce different cron schedules in action mode")
 }
 
 func TestGenerateAutoUpdateWorkflow_NoRepoSlug(t *testing.T) {
@@ -180,9 +184,57 @@ func TestGenerateAutoUpdateWorkflow_ReleaseModeUsesGhAwPrefix(t *testing.T) {
 	assert.NotContains(t, string(content), "Build gh-aw", "should not build gh-aw from source in release mode")
 }
 
+func TestGenerateAutoUpdateWorkflow_DevModeScheduleStable(t *testing.T) {
+	// Dev mode must produce the same schedule regardless of whether --schedule-seed /
+	// a repo slug is provided. This is the key stability property: agents and CI that
+	// call `gh aw compile` without --schedule-seed should not cause agentic-auto-upgrade.yml
+	// to differ from a build that passes --schedule-seed.
+	dir1 := t.TempDir()
+	dir2 := t.TempDir()
+
+	require.NoError(t, GenerateAutoUpdateWorkflow(GenerateAutoUpdateWorkflowOptions{
+		WorkflowDir: dir1,
+		Enabled:     true,
+		RepoSlug:    "github/gh-aw", // simulates --schedule-seed github/gh-aw
+		ActionMode:  ActionModeDev,
+	}))
+	require.NoError(t, GenerateAutoUpdateWorkflow(GenerateAutoUpdateWorkflowOptions{
+		WorkflowDir: dir2,
+		Enabled:     true,
+		RepoSlug:    "", // simulates sandbox/CI where git remote detection yields empty slug
+		ActionMode:  ActionModeDev,
+	}))
+
+	data1, err := os.ReadFile(filepath.Join(dir1, AutoUpdateWorkflowFileName))
+	require.NoError(t, err)
+	data2, err := os.ReadFile(filepath.Join(dir2, AutoUpdateWorkflowFileName))
+	require.NoError(t, err)
+
+	cron1 := extractCronLine(string(data1))
+	cron2 := extractCronLine(string(data2))
+	assert.NotEmpty(t, cron1, "cron should be present with slug in dev mode")
+	assert.NotEmpty(t, cron2, "cron should be present without slug in dev mode")
+	assert.Equal(t, cron1, cron2, "dev mode schedule must be identical regardless of repo slug")
+}
+
 func TestBuildAutoUpdateSeed(t *testing.T) {
-	assert.Equal(t, "owner/repo/agentic-auto-upgrade", buildAutoUpdateSeed("owner/repo"))
-	assert.Equal(t, "agentic-auto-upgrade", buildAutoUpdateSeed(""))
+	// Release mode: incorporates repo slug for per-repo scattering.
+	assert.Equal(t, "owner/repo/agentic-auto-upgrade", buildAutoUpdateSeed("owner/repo", ActionModeRelease))
+	assert.Equal(t, "agentic-auto-upgrade", buildAutoUpdateSeed("", ActionModeRelease))
+
+	// Action mode (used by released binaries): also incorporates repo slug for per-repo scattering.
+	assert.Equal(t, "owner/repo/agentic-auto-upgrade", buildAutoUpdateSeed("owner/repo", ActionModeAction))
+	assert.Equal(t, "agentic-auto-upgrade", buildAutoUpdateSeed("", ActionModeAction))
+
+	// Script mode: also incorporates repo slug for per-repo scattering.
+	assert.Equal(t, "owner/repo/agentic-auto-upgrade", buildAutoUpdateSeed("owner/repo", ActionModeScript))
+	assert.Equal(t, "agentic-auto-upgrade", buildAutoUpdateSeed("", ActionModeScript))
+
+	// Dev mode: always uses the stable "dev/" prefix regardless of repo slug,
+	// so that the schedule does not change depending on whether --schedule-seed
+	// is passed or whether git remote detection succeeds.
+	assert.Equal(t, "dev/agentic-auto-upgrade", buildAutoUpdateSeed("owner/repo", ActionModeDev))
+	assert.Equal(t, "dev/agentic-auto-upgrade", buildAutoUpdateSeed("", ActionModeDev))
 }
 
 // extractCronLine returns the cron expression from the first `- cron:` line in the YAML.