fix(dashboard): address model-lane drift review feedback

- getModelLaneDrift now takes an explicit includeNullSelection option; the
  setting-values route passes it when patching the project default workflow so
  no-workflow-selection tasks (which resolve through the default) are counted
  instead of silently dropped (Greptile P1).
- Add updateWorkflowSettingValuesWithPrevious so the drift baseline is captured
  inside the settings write transaction, removing the stale-read race against a
  concurrent patch of the same row (Greptile P2).
- Broaden getModelLaneDrift tests to cover planning and validator lanes and the
  null-selection/default-workflow case (FN-5893 invariant across surfaces).
- Add changeset.

CodeRabbit's effective-values suggestion is intentionally skipped: model-lane
declarations carry no declaration-level default (KTD-7), so effective == raw for
these keys and comparing effective values is a no-op.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.changeset/fix-model-lane-drift-visibility.md

@@ -0,0 +1,7 @@
+---
+"@runfusion/fusion": patch
+---
+
+summary: Warn when changing a workflow's model surfaces tasks still pinned to the old model, including default-workflow tasks.
+category: fix
+dev: PATCH /workflows/:id/setting-values now returns `modelDrift` for execution/planning/validator lanes. Drift baseline is captured inside the settings write transaction (no stale-read race), and default-workflow patches pass `includeNullSelection` so no-workflow-selection tasks are counted. New `TaskStore.updateWorkflowSettingValuesWithPrevious` and `getModelLaneDrift(..., { includeNullSelection })`.

packages/core/src/__tests__/workflow-settings.test.ts

@@ -374,4 +374,87 @@ describe("TaskStore.getModelLaneDrift", () => {
 
     expect(store.getModelLaneDrift(BUILTIN_CODING, before, after)).toEqual([]);
   });
+
+  // FN-5893: the invariant holds across ALL model lanes, not only `execution`.
+  it("flags the planning lane's pinned tasks when the planning model changes", async () => {
+    const store = harness.store();
+    await store.updateWorkflowSettingValues(BUILTIN_CODING, PROJECT, {
+      planningProvider: "anthropic",
+      planningModelId: "claude-opus-4-6",
+    });
+    const before = store.getWorkflowSettingValues(BUILTIN_CODING, PROJECT);
+    const pinned = await store.createTask({
+      description: "pinned to old planning model",
+      workflowId: BUILTIN_CODING,
+      planningModelProvider: "anthropic",
+      planningModelId: "claude-opus-4-6",
+    });
+    await store.updateWorkflowSettingValues(BUILTIN_CODING, PROJECT, {
+      planningModelId: "claude-opus-4-8",
+    });
+    const after = store.getWorkflowSettingValues(BUILTIN_CODING, PROJECT);
+
+    const drift = store.getModelLaneDrift(BUILTIN_CODING, before, after);
+    expect(drift).toHaveLength(1);
+    expect(drift[0].lane).toBe("planning");
+    expect(drift[0].taskIds).toEqual([pinned.id]);
+  });
+
+  it("flags the validator lane's pinned tasks when the validator model changes", async () => {
+    const store = harness.store();
+    await store.updateWorkflowSettingValues(BUILTIN_CODING, PROJECT, {
+      validatorProvider: "anthropic",
+      validatorModelId: "claude-haiku-4-5",
+    });
+    const before = store.getWorkflowSettingValues(BUILTIN_CODING, PROJECT);
+    const pinned = await store.createTask({
+      description: "pinned to old validator model",
+      workflowId: BUILTIN_CODING,
+      validatorModelProvider: "anthropic",
+      validatorModelId: "claude-haiku-4-5",
+    });
+    await store.updateWorkflowSettingValues(BUILTIN_CODING, PROJECT, {
+      validatorModelId: "claude-haiku-5",
+    });
+    const after = store.getWorkflowSettingValues(BUILTIN_CODING, PROJECT);
+
+    const drift = store.getModelLaneDrift(BUILTIN_CODING, before, after);
+    expect(drift).toHaveLength(1);
+    expect(drift[0].lane).toBe("validator");
+    expect(drift[0].taskIds).toEqual([pinned.id]);
+  });
+
+  // Greptile P1: when the default workflow is diffed, no-selection tasks resolve
+  // through it and are pinned to its lane values, so they must be counted — but
+  // only when the caller opts in via `includeNullSelection`.
+  it("includes no-workflow-selection tasks only when includeNullSelection is set", async () => {
+    const store = harness.store();
+    await store.updateWorkflowSettingValues(BUILTIN_CODING, PROJECT, {
+      executionProvider: "anthropic",
+      executionModelId: "claude-sonnet-4-6",
+    });
+    const before = store.getWorkflowSettingValues(BUILTIN_CODING, PROJECT);
+    // No workflowId → no task_workflow_selection row → resolves to the default.
+    const nullSelected = await store.createTask({
+      description: "no workflow selection, pinned to old model",
+      modelProvider: "anthropic",
+      modelId: "claude-sonnet-4-6",
+    });
+    await store.updateWorkflowSettingValues(BUILTIN_CODING, PROJECT, {
+      executionModelId: "claude-sonnet-5",
+    });
+    const after = store.getWorkflowSettingValues(BUILTIN_CODING, PROJECT);
+
+    // Default excludes null-selection tasks: the route passes a concrete id.
+    const withoutNull = store.getModelLaneDrift(BUILTIN_CODING, before, after);
+    expect(withoutNull).toHaveLength(1);
+    expect(withoutNull[0].taskIds).not.toContain(nullSelected.id);
+
+    // Opt in (the route does this when patching the default workflow).
+    const withNull = store.getModelLaneDrift(BUILTIN_CODING, before, after, {
+      includeNullSelection: true,
+    });
+    expect(withNull).toHaveLength(1);
+    expect(withNull[0].taskIds).toContain(nullSelected.id);
+  });
 });

packages/core/src/store.ts

@@ -8798,6 +8798,22 @@ ${TASK_UPSERT_SQL_ASSIGNMENTS}
     projectId: string,
     patch: Record<string, unknown>,
   ): Promise<Record<string, unknown>> {
+    return (await this.updateWorkflowSettingValuesWithPrevious(workflowId, projectId, patch)).stored;
+  }
+
+  /**
+   * Like {@link updateWorkflowSettingValues} but also returns the row's value
+   * snapshot as it was read INSIDE the same serialized transaction, immediately
+   * before the merge. Callers that diff before→after (e.g. model-lane drift on
+   * `PATCH /workflows/:id/setting-values`) must use this — reading `before`
+   * outside the write transaction races a concurrent patch of the same row and
+   * can pair a stale `previous` with another writer's `stored` (Greptile P2).
+   */
+  async updateWorkflowSettingValuesWithPrevious(
+    workflowId: string,
+    projectId: string,
+    patch: Record<string, unknown>,
+  ): Promise<{ previous: Record<string, unknown>; stored: Record<string, unknown> }> {
     const declarations = await this.resolveWorkflowSettingDeclarations(workflowId);
     const result = validateSettingValuePatch(declarations, patch);
     if (result.rejections.length > 0) {
@@ -8812,8 +8828,8 @@ ${TASK_UPSERT_SQL_ASSIGNMENTS}
     // write transaction. Validation/declaration resolution above stays outside
     // since it's async and doesn't read the row being mutated.
     return this.db.transactionImmediate(() => {
-      const current = this.getWorkflowSettingValues(workflowId, projectId);
-      const next: Record<string, unknown> = { ...current };
+      const previous = this.getWorkflowSettingValues(workflowId, projectId);
+      const next: Record<string, unknown> = { ...previous };
       for (const [key, value] of Object.entries(result.accepted)) {
         if (value === null) {
           delete next[key];
@@ -8832,7 +8848,9 @@ ${TASK_UPSERT_SQL_ASSIGNMENTS}
         )
         .run(workflowId, projectId, JSON.stringify(next), now);
       this.db.bumpLastModified();
-      return next;
+      // `previous` is captured before the merge; it and `next` are a consistent
+      // before/after pair from the same transaction snapshot.
+      return { previous, stored: next };
     });
   }
 
@@ -15823,11 +15841,19 @@ ${stepsSection}`;
    * so changing a workflow's default silently orphans already-created tasks
    * unless this drift is surfaced. Read-only — never mutates `tasks`; pair
    * with `POST /tasks/batch-update-models` to actually re-pin flagged ids.
+   *
+   * When the diffed workflow is the project default, no-selection tasks resolve
+   * THROUGH it and are pinned to its lane values, so they must be counted as
+   * occupants. Callers pass `includeNullSelection: true` in that case (the
+   * route never hands us the internal `DEFAULT_WORKFLOW_POOL_ID` sentinel — it
+   * has the concrete default id — so we cannot infer this from `workflowId`
+   * alone; Greptile P1). When omitted, it falls back to the sentinel check.
    */
   getModelLaneDrift(
     workflowId: string,
     before: Record<string, unknown>,
     after: Record<string, unknown>,
+    options?: { includeNullSelection?: boolean },
   ): Array<{
     lane: string;
     from: { provider: string | null; modelId: string | null };
@@ -15835,7 +15861,8 @@ ${stepsSection}`;
     taskIds: string[];
   }> {
     const asStringOrNull = (v: unknown): string | null => (typeof v === "string" ? v : null);
-    const includeNullSelection = workflowId === TaskStore.DEFAULT_WORKFLOW_POOL_ID;
+    const includeNullSelection =
+      options?.includeNullSelection ?? workflowId === TaskStore.DEFAULT_WORKFLOW_POOL_ID;
     const drift: Array<{
       lane: string;
       from: { provider: string | null; modelId: string | null };

packages/dashboard/src/routes/register-workflow-routes.ts

@@ -481,8 +481,11 @@ export function registerWorkflowRoutes(ctx: ApiRoutesContext): void {
       await assertWorkflowExists(store, workflowId);
       const projectId = store.getWorkflowSettingsProjectId();
       try {
-        const before = store.getWorkflowSettingValues(workflowId, projectId);
-        const stored = await store.updateWorkflowSettingValues(
+        // FNXC:ModelLaneDrift 2026-07-08-07:24:
+        // Capture `before` INSIDE the write transaction (paired with `stored`)
+        // so a concurrent patch of the same row cannot pair a stale baseline
+        // with another writer's result (Greptile P2).
+        const { previous: before, stored } = await store.updateWorkflowSettingValuesWithPrevious(
           workflowId,
           projectId,
           values as Record<string, unknown>,
@@ -491,7 +494,17 @@ export function registerWorkflowRoutes(ctx: ApiRoutesContext): void {
         // Model-lane drift: tasks already pinned to the value being replaced
         // are never auto-resynced (see getModelLaneDrift), so surface them
         // here rather than let the change silently orphan those tasks.
-        const modelDrift = store.getModelLaneDrift(workflowId, before, stored).filter((d) => d.taskIds.length > 0);
+        // FNXC:ModelLaneDrift 2026-07-08-07:24:
+        // When the patched workflow is the project default, no-selection tasks
+        // resolve through it and must be counted, so flag includeNullSelection
+        // then (Greptile P1) — the route holds the concrete default id, not the
+        // internal DEFAULT_WORKFLOW_POOL_ID sentinel getModelLaneDrift checks.
+        const defaultWorkflowId = (await store.getDefaultWorkflowId()) ?? "builtin:coding";
+        const modelDrift = store
+          .getModelLaneDrift(workflowId, before, stored, {
+            includeNullSelection: workflowId === defaultWorkflowId,
+          })
+          .filter((d) => d.taskIds.length > 0);
         res.json({
           stored,
           effective: resolveEffectiveSettingValues(declarations, stored),