diff --git a/apps/server/src/review/ReviewService.test.ts b/apps/server/src/review/ReviewService.test.ts
index 839eb73b2bb..fc113ba7652 100644
--- a/apps/server/src/review/ReviewService.test.ts
+++ b/apps/server/src/review/ReviewService.test.ts
@@ -1,19 +1,36 @@
 import * as NodeServices from "@effect/platform-node/NodeServices";
 import { assert, describe, it } from "@effect/vitest";
+import { type OrchestrationProject, ProjectId } from "@t3tools/contracts";
 import * as Effect from "effect/Effect";
 import * as FileSystem from "effect/FileSystem";
 import * as Layer from "effect/Layer";
+import * as Option from "effect/Option";
 import * as PlatformError from "effect/PlatformError";
 
 import { ServerConfig } from "../config.ts";
+import * as ProjectionSnapshotQuery from "../orchestration/Services/ProjectionSnapshotQuery.ts";
 import * as GitVcsDriver from "../vcs/GitVcsDriver.ts";
 import * as VcsDriverRegistry from "../vcs/VcsDriverRegistry.ts";
 import * as ReviewService from "./ReviewService.ts";
 
+function makeProject(workspaceRoot: string): OrchestrationProject {
+  return {
+    id: ProjectId.make("project-1"),
+    title: "Project",
+    workspaceRoot,
+    defaultModelSelection: null,
+    scripts: [],
+    createdAt: "2026-01-01T00:00:00.000Z",
+    updatedAt: "2026-01-01T00:00:00.000Z",
+    deletedAt: null,
+  };
+}
+
 function makeLayer(input: {
   readonly workspaceRoot: string;
   readonly baseDir: string;
   readonly detectCalls?: Array<{ readonly cwd: string }>;
+  readonly registeredProjectRoots?: ReadonlyArray<string>;
 }) {
   return ReviewService.layer.pipe(
     Layer.provide(
@@ -28,6 +45,16 @@ function makeLayer(input: {
       }),
     ),
     Layer.provide(Layer.mock(GitVcsDriver.GitVcsDriver)({})),
+    Layer.provide(
+      Layer.mock(ProjectionSnapshotQuery.ProjectionSnapshotQuery)({
+        getActiveProjectByWorkspaceRoot: (workspaceRoot) =>
+          Effect.succeed(
+            input.registeredProjectRoots?.includes(workspaceRoot) === true
+              ? Option.some(makeProject(workspaceRoot))
+              : Option.none(),
+          ),
+      }),
+    ),
     Layer.provide(ServerConfig.layerTest(input.workspaceRoot, input.baseDir)),
     Layer.provideMerge(NodeServices.layer),
   );
@@ -75,6 +102,34 @@ describe("ReviewService", () => {
     }).pipe(Effect.provide(NodeServices.layer)),
   );
 
+  it.effect("allows diff preview cwd matching a registered project workspace root", () =>
+    Effect.gen(function* () {
+      const fs = yield* FileSystem.FileSystem;
+      const workspaceRoot = yield* fs.makeTempDirectoryScoped({ prefix: "t3-review-workspace-" });
+      const projectRoot = yield* fs.makeTempDirectoryScoped({ prefix: "t3-review-project-" });
+      const baseDir = yield* fs.makeTempDirectoryScoped({ prefix: "t3-review-base-" });
+      const detectCalls: Array<{ readonly cwd: string }> = [];
+
+      const result = yield* Effect.gen(function* () {
+        const review = yield* ReviewService.ReviewService;
+        return yield* review.getDiffPreview({ cwd: projectRoot });
+      }).pipe(
+        Effect.provide(
+          makeLayer({
+            workspaceRoot,
+            baseDir,
+            detectCalls,
+            registeredProjectRoots: [projectRoot],
+          }),
+        ),
+      );
+
+      assert.strictEqual(result.cwd, projectRoot);
+      assert.deepStrictEqual(result.sources, []);
+      assert.deepStrictEqual(detectCalls, [{ cwd: projectRoot }]);
+    }).pipe(Effect.provide(NodeServices.layer)),
+  );
+
   it.effect("preserves unexpected path-resolution failures", () =>
     Effect.gen(function* () {
       const fs = yield* FileSystem.FileSystem;
diff --git a/apps/server/src/review/ReviewService.ts b/apps/server/src/review/ReviewService.ts
index db1dc5bc8d2..ee862d0e95d 100644
--- a/apps/server/src/review/ReviewService.ts
+++ b/apps/server/src/review/ReviewService.ts
@@ -3,6 +3,7 @@ import * as DateTime from "effect/DateTime";
 import * as Effect from "effect/Effect";
 import * as FileSystem from "effect/FileSystem";
 import * as Layer from "effect/Layer";
+import * as Option from "effect/Option";
 import * as Path from "effect/Path";
 
 import {
@@ -14,6 +15,7 @@ import {
 } from "@t3tools/contracts";
 
 import * as ServerConfig from "../config.ts";
+import * as ProjectionSnapshotQuery from "../orchestration/Services/ProjectionSnapshotQuery.ts";
 import * as GitVcsDriver from "../vcs/GitVcsDriver.ts";
 import * as VcsDriverRegistry from "../vcs/VcsDriverRegistry.ts";
 
@@ -30,6 +32,7 @@ export const make = Effect.gen(function* () {
   const config = yield* ServerConfig.ServerConfig;
   const fileSystem = yield* FileSystem.FileSystem;
   const path = yield* Path.Path;
+  const projectionSnapshotQuery = yield* ProjectionSnapshotQuery.ProjectionSnapshotQuery;
   const vcsRegistry = yield* VcsDriverRegistry.VcsDriverRegistry;
   const git = yield* GitVcsDriver.GitVcsDriver;
 
@@ -70,6 +73,25 @@ export const make = Effect.gen(function* () {
       return;
     }
 
+    const registeredProject = yield* projectionSnapshotQuery
+      .getActiveProjectByWorkspaceRoot(cwd)
+      .pipe(
+        Effect.map(Option.isSome),
+        Effect.mapError(
+          (cause) =>
+            new VcsRepositoryDetectionError({
+              operation: "ReviewService.assertWorkspaceBoundCwd.resolveRegisteredProject",
+              cwd,
+              detail:
+                "Failed to resolve the registered project while validating the review workspace.",
+              cause,
+            }),
+        ),
+      );
+    if (registeredProject) {
+      return;
+    }
+
     return yield* new VcsRepositoryDetectionError({
       operation: "ReviewService.getDiffPreview",
       cwd,
diff --git a/apps/web/src/components/DiffPanel.tsx b/apps/web/src/components/DiffPanel.tsx
index 5cb2a1cfdea..db1abff996d 100644
--- a/apps/web/src/components/DiffPanel.tsx
+++ b/apps/web/src/components/DiffPanel.tsx
@@ -322,7 +322,7 @@ export default function DiffPanel({
     },
     { enabled: isGitRepo && selectedTurn !== undefined },
   );
-  const primaryBranchDiffPreview = useEnvironmentQuery(
+  const branchDiffPreview = useEnvironmentQuery(
     selectedTurnId === null && activeThread && activeCwd
       ? reviewEnvironment.diffPreview({
           environmentId: activeThread.environmentId,
@@ -334,26 +334,6 @@ export default function DiffPanel({
         })
       : null,
   );
-  const shouldRetryBranchDiffAtEnvironmentCwd =
-    selectedTurnId === null &&
-    primaryBranchDiffPreview.error?.includes("configured workspace root") === true &&
-    serverConfig?.cwd !== undefined &&
-    serverConfig.cwd !== activeCwd;
-  const fallbackBranchDiffPreview = useEnvironmentQuery(
-    shouldRetryBranchDiffAtEnvironmentCwd && activeThread && serverConfig
-      ? reviewEnvironment.diffPreview({
-          environmentId: activeThread.environmentId,
-          input: {
-            cwd: serverConfig.cwd,
-            ...(selectedBaseRef ? { baseRef: selectedBaseRef } : {}),
-            ignoreWhitespace: diffIgnoreWhitespace,
-          },
-        })
-      : null,
-  );
-  const branchDiffPreview = shouldRetryBranchDiffAtEnvironmentCwd
-    ? fallbackBranchDiffPreview
-    : primaryBranchDiffPreview;
   const selectedGitSource = branchDiffPreview.data?.sources.find(
     (source) => source.kind === (selectedGitScope === "unstaged" ? "working-tree" : "branch-range"),
   );