fix(installer): complete literal paths and recovery guidance

fix(geometry): preserve OOPIF scale with occupied scrollbars

apps/extension/src/tools/__tests__/file-transfer.test.ts

@@ -436,6 +436,8 @@ describe("file transfer tools", () => {
         if (method === "DOM.getContentQuads") {
           return { quads: [[10, 20, 210, 20, 210, 120, 10, 120]] };
         }
+        if (method === "Runtime.evaluate")
+          return { result: { value: { width: 400, height: 300 } } };
         if (method === "Page.getLayoutMetrics") {
           return { cssLayoutViewport: { clientWidth: 400, clientHeight: 300 } };
         }

apps/extension/src/tools/__tests__/frame-geometry.test.ts

@@ -13,7 +13,138 @@ import {
 import { GeometryContext } from "../geometry/frame-context";
 import type { CdpRunner } from "../shared";
 
+function scrollbarDriver(
+  visible = { width: 185, height: 89 },
+  frameSize: unknown = { width: 200, height: 100 },
+) {
+  const send = vi.fn(async (target: { sessionId?: string }, method: string) => {
+    if (method === "Runtime.evaluate") return { result: { value: frameSize } };
+    if (method === "Page.getLayoutMetrics")
+      return {
+        cssLayoutViewport: {
+          clientWidth: target.sessionId ? visible.width : 800,
+          clientHeight: target.sessionId ? visible.height : 600,
+        },
+      };
+    if (method === "DOM.getBoxModel")
+      return {
+        model: {
+          content: target.sessionId
+            ? [0, 0, 200, 0, 200, 100, 0, 100]
+            : [100, 100, 500, 100, 500, 300, 100, 300],
+        },
+      };
+    if (method === "DOM.getContentQuads")
+      return { quads: [[180, 80, 230, 80, 230, 120, 180, 120]] };
+    throw new Error(`unexpected ${method}`);
+  });
+  const cdp: CdpRunner = {
+    send: (tabId, method) => send({ tabId } as never, method) as never,
+    sendToTarget: send as CdpRunner["sendToTarget"],
+    getFrameGraph: async () => ({
+      rootFrameId: "main",
+      frames: [
+        { frameId: "main", target: { tabId: 4 } },
+        {
+          frameId: "child",
+          parentFrameId: "main",
+          ownerBackendNodeId: 10,
+          target: { tabId: 4, sessionId: "child" },
+        },
+        {
+          frameId: "same-child",
+          parentFrameId: "child",
+          ownerBackendNodeId: 20,
+          target: { tabId: 4, sessionId: "child" },
+        },
+      ],
+    }),
+  };
+  return { cdp, send };
+}
+
 describe("frame geometry projection", () => {
+  it.each([
+    { width: 200, height: 100 },
+    { width: 185, height: 100 },
+    { width: 200, height: 89 },
+    { width: 185, height: 89 },
+  ])("preserves scale and clips scrollbar strips for visible viewport $width × $height", async (visible) => {
+    const { cdp, send } = scrollbarDriver(visible);
+    const geometry = await resolveNodeGeometry(cdp, 4, {
+      target: { tabId: 4, sessionId: "child" },
+      frameId: "child",
+      backendNodeId: 101,
+    });
+    expect(geometry).toMatchObject({
+      topBounds: {
+        x: 460,
+        y: 260,
+        width: (visible.width - 180) * 2,
+        height: (visible.height - 80) * 2,
+      },
+      actionPoint: { x: 460 + visible.width - 180, y: 260 + visible.height - 80 },
+      targetActionPoint: { x: (180 + visible.width) / 2, y: (80 + visible.height) / 2 },
+    });
+    expect(send.mock.calls.filter(([, method]) => method === "Runtime.evaluate")).toHaveLength(1);
+    expect(send.mock.calls.filter(([, method]) => method === "Page.getLayoutMetrics")).toHaveLength(
+      2,
+    );
+  });
+
+  it("shares the full viewport read across same-target frames, and refreshes it next operation", async () => {
+    const { cdp, send } = scrollbarDriver();
+    const context = new GeometryContext(cdp, 4);
+    await Promise.all([context.targetProjection("child"), context.targetProjection("same-child")]);
+    expect(send.mock.calls.filter(([, method]) => method === "Runtime.evaluate")).toHaveLength(1);
+    await new GeometryContext(cdp, 4).targetProjection("child");
+    expect(send.mock.calls.filter(([, method]) => method === "Runtime.evaluate")).toHaveLength(2);
+  });
+
+  it.each([
+    null,
+    {},
+    { width: 0, height: 100 },
+    { width: 200, height: NaN },
+  ])("rejects unavailable full viewport dimensions: %j", async (size) => {
+    const { cdp } = scrollbarDriver(undefined, size);
+    expect(await new GeometryContext(cdp, 4).targetProjection("child")).toBeNull();
+  });
+
+  it("clips an inner OOPIF against an intermediate OOPIF's occupied scrollbar strips", async () => {
+    const { cdp } = scrollbarDriver();
+    const outer = cdp.sendToTarget!;
+    cdp.sendToTarget = async (target, method, params) => {
+      if (method === "DOM.getBoxModel")
+        return { model: { content: [150, 60, 250, 60, 250, 120, 150, 120] } } as never;
+      if (target.sessionId !== "inner") return outer(target, method, params);
+      if (method === "Runtime.evaluate")
+        return { result: { value: { width: 100, height: 60 } } } as never;
+      if (method === "Page.getLayoutMetrics")
+        return { cssLayoutViewport: { clientWidth: 90, clientHeight: 50 } } as never;
+      if (method === "DOM.getContentQuads")
+        return { quads: [[0, 0, 100, 0, 100, 60, 0, 60]] } as never;
+      throw new Error(`unexpected ${method}`);
+    };
+    const graph = await cdp.getFrameGraph!(4);
+    graph.frames[2] = {
+      frameId: "inner",
+      parentFrameId: "child",
+      ownerBackendNodeId: 20,
+      target: { tabId: 4, sessionId: "inner" },
+    };
+    cdp.getFrameGraph = async () => graph;
+    expect(
+      await resolveNodeGeometry(cdp, 4, {
+        target: { tabId: 4, sessionId: "inner" },
+        frameId: "inner",
+        backendNodeId: 101,
+      }),
+    ).toMatchObject({
+      topBounds: { x: 400, y: 220, width: 70, height: 58 },
+    });
+  });
+
   it("keeps region bounds separate from polygon area", () => {
     const region = [
       rectPolygon({ x: 0, y: 0, w: 10, h: 10 }),
@@ -77,6 +208,8 @@ describe("frame geometry projection", () => {
     const cdp: CdpRunner = {
       send: send as CdpRunner["send"],
       sendToTarget: vi.fn(async (_target, method) => {
+        if (method === "Runtime.evaluate")
+          return { result: { value: { width: 200, height: 100 } } };
         if (method === "Page.getLayoutMetrics") {
           return { cssLayoutViewport: { clientWidth: 200, clientHeight: 100 } };
         }
@@ -135,6 +268,8 @@ describe("frame geometry projection", () => {
         throw new Error(`unexpected root command ${method}`);
       }) as CdpRunner["send"],
       sendToTarget: vi.fn(async (_target, method) => {
+        if (method === "Runtime.evaluate")
+          return { result: { value: { width: 200, height: 100 } } };
         if (method === "Page.getLayoutMetrics") {
           return { cssLayoutViewport: { clientWidth: 200, clientHeight: 100 } };
         }
@@ -196,6 +331,8 @@ describe("frame geometry projection", () => {
       }) as CdpRunner["send"],
       sendToTarget: vi.fn(async (_target, method) => {
         if (method === "DOM.scrollIntoViewIfNeeded") return {};
+        if (method === "Runtime.evaluate")
+          return { result: { value: { width: 200, height: 100 } } };
         if (method === "Page.getLayoutMetrics") {
           return { cssLayoutViewport: { clientWidth: 200, clientHeight: 100 } };
         }

apps/extension/src/tools/__tests__/human-loop.test.ts

@@ -433,6 +433,7 @@ describe("handleRequestHelp", () => {
       if (method === "DOM.getContentQuads") {
         return { quads: [[10, 20, 110, 20, 110, 60, 10, 60]] };
       }
+      if (method === "Runtime.evaluate") return { result: { value: { width: 200, height: 100 } } };
       if (method === "Page.getLayoutMetrics") {
         return { cssLayoutViewport: { clientWidth: 200, clientHeight: 100 } };
       }

apps/extension/src/tools/__tests__/interaction.test.ts

@@ -201,6 +201,7 @@ describe("handleClick", () => {
       if (method === "DOM.getContentQuads") {
         return { quads: [[10, 20, 110, 20, 110, 60, 10, 60]] };
       }
+      if (method === "Runtime.evaluate") return { result: { value: { width: 200, height: 100 } } };
       if (method === "Page.getLayoutMetrics") {
         return { cssLayoutViewport: { clientWidth: 200, clientHeight: 100 } };
       }
@@ -220,6 +221,7 @@ describe("handleClick", () => {
       { sessionId: "child-session", method: "DOM.scrollIntoViewIfNeeded" },
       { sessionId: "child-session", method: "DOM.getContentQuads" },
       { sessionId: "child-session", method: "Page.getLayoutMetrics" },
+      { sessionId: "child-session", method: "Runtime.evaluate" },
     ]);
     expect(fake.sent.filter((call) => call.method === "Input.dispatchMouseEvent")).toHaveLength(3);
   });

apps/extension/src/tools/__tests__/observation.test.ts

@@ -3380,6 +3380,7 @@ describe("handleSnapshot", () => {
       throw new Error(`unexpected root CDP method ${method}`);
     });
     const sendToTarget = vi.fn(async (_target, method: string) => {
+      if (method === "Runtime.evaluate") return { result: { value: { width: 400, height: 300 } } };
       if (method === "Page.getLayoutMetrics" && ownerGeometry !== "unavailable")
         return {
           visualViewport: { clientWidth: 1000 },

apps/extension/src/tools/__tests__/snapshot-coordinates.browser.test.ts

@@ -1,6 +1,7 @@
 // @vitest-environment node
 import { describe, expect, it } from "vitest";
 import type { CdpFrame, CdpFrameGraph, CdpTarget } from "@/browser-driver/frame-graph";
+import { resolveNodeGeometry } from "../frame-geometry";
 import type { CdpRunner } from "../shared";
 import { captureObservationFacts } from "../vom/capture-coordinator";
 
@@ -11,12 +12,28 @@ type Send = <T = Record<string, unknown>>(
 ) => Promise<T>;
 type Tree = { frame: { id: string; parentId?: string; name?: string }; childFrames?: Tree[] };
 type Rect = { x: number; y: number; w: number; h: number };
-type Oracle = { probe: Rect; owners: Record<string, { x: number; y: number; scale: number }> };
+type Oracle = {
+  probes: Record<string, Rect>;
+  viewport: { width: number; height: number };
+  owners: Record<string, { x: number; y: number; scale: number }>;
+};
+
+function clip(rect: Rect, viewport: Oracle["viewport"]): Rect | null {
+  const x = Math.max(0, rect.x),
+    y = Math.max(0, rect.y);
+  const right = Math.min(viewport.width, rect.x + rect.w);
+  const bottom = Math.min(viewport.height, rect.y + rect.h);
+  return right > x && bottom > y ? { x, y, w: right - x, h: bottom - y } : null;
+}
 
 // The independent oracle uses DOM border boxes and this fixture's axis-aligned
 // iframe transforms. No production snapshot conversion/projection builds expectations.
 const oracleExpression = `(() => {
-  const box = document.querySelector('#probe').getBoundingClientRect();
+  const probes = {};
+  for (const node of document.querySelectorAll('[data-geometry-probe]')) {
+    const box = node.getBoundingClientRect();
+    probes[node.id] = { x: box.x, y: box.y, w: box.width, h: box.height };
+  }
   const owners = {};
   for (const frame of document.querySelectorAll('iframe')) {
     const rect = frame.getBoundingClientRect();
@@ -28,17 +45,31 @@ const oracleExpression = `(() => {
       scale,
     };
   }
-  return { probe: { x: box.x, y: box.y, w: box.width, h: box.height }, owners };
+  return { probes, viewport: { width: document.documentElement.clientWidth, height: document.documentElement.clientHeight }, owners };
 })()`;
 
 describe.skipIf(!process.env.BSK_GEOMETRY_CHROME)("real DOMSnapshot coordinate contract", () => {
-  it.each([
-    { deviceScale: 1, zoom: 1 },
-    { deviceScale: 0.8, zoom: 1 },
-    { deviceScale: 1, zoom: 1.25 },
-    { deviceScale: 2, zoom: 1 },
-    { deviceScale: 2, zoom: 0.8 },
-  ])("matches DOM geometry at device scale $deviceScale and zoom $zoom", async (configuration) => {
+  it.each(
+    [
+      { deviceScale: 1, zoom: 1 },
+      { deviceScale: 0.8, zoom: 1 },
+      { deviceScale: 1, zoom: 1.25 },
+      { deviceScale: 2, zoom: 1 },
+      { deviceScale: 2, zoom: 0.8 },
+    ]
+      .flatMap((configuration) => [
+        { ...configuration, fixture: "snapshot-coordinates", scrollbars: "none" },
+        { ...configuration, fixture: "oopif-scrollbars", scrollbars: "both" },
+      ])
+      .concat(
+        ["vertical", "horizontal", "none"].map((scrollbars) => ({
+          deviceScale: 1,
+          zoom: 1,
+          fixture: "oopif-scrollbars",
+          scrollbars,
+        })),
+      ),
+  )("$fixture: device scale $deviceScale, zoom $zoom, scrollbars $scrollbars", async (configuration) => {
     const evalRoot = new URL("../../../../../evals/browser/", import.meta.url);
     const { createEvalServer } = await import(new URL("lib/server.mjs", evalRoot).href);
     const { withChrome } = await import(
@@ -59,7 +90,9 @@ describe.skipIf(!process.env.BSK_GEOMETRY_CHROME)("real DOMSnapshot coordinate c
           );
           await send(
             "Page.navigate",
-            { url: `${baseUrl}/snapshot-coordinates?run=coordinates` },
+            {
+              url: `${baseUrl}/${configuration.fixture}?run=coordinates&scrollbars=${configuration.scrollbars}`,
+            },
             rootSession,
           );
           await expect
@@ -86,7 +119,7 @@ describe.skipIf(!process.env.BSK_GEOMETRY_CHROME)("real DOMSnapshot coordinate c
             });
             sessions.push(sessionId);
           }
-          expect(sessions.length).toBe(2); // The cross-site fixture must actually be an OOPIF.
+          expect(sessions.length).toBe(configuration.fixture === "oopif-scrollbars" ? 3 : 2);
           const frames: CdpFrame[] = [];
           const names = new Map<string, string>();
           const sessionFor = (target: CdpTarget) => target.sessionId ?? rootSession;
@@ -107,7 +140,7 @@ describe.skipIf(!process.env.BSK_GEOMETRY_CHROME)("real DOMSnapshot coordinate c
             };
             visit(frameTree);
           }
-          expect(frames).toHaveLength(5);
+          expect(frames).toHaveLength(configuration.fixture === "oopif-scrollbars" ? 3 : 5);
           for (const frame of frames) {
             if (!frame.parentFrameId) continue;
             const parent = frames.find((item) => item.frameId === frame.parentFrameId)!;
@@ -127,6 +160,11 @@ describe.skipIf(!process.env.BSK_GEOMETRY_CHROME)("real DOMSnapshot coordinate c
             },
             sendToTarget: (target, method, params) => {
               calls.push(`${target.sessionId ?? target.tabId}:${method}`);
+              if (
+                method === "Runtime.evaluate" &&
+                (params as { expression?: string })?.expression?.includes("window.innerWidth")
+              )
+                calls.push(`${target.sessionId ?? target.tabId}:viewport-size`);
               return send(method, params, sessionFor(target));
             },
             getFrameGraph: async () => graph,
@@ -179,47 +217,130 @@ describe.skipIf(!process.env.BSK_GEOMETRY_CHROME)("real DOMSnapshot coordinate c
             );
             oracles.set(frame.frameId, reply.result.value);
           }
+          const childViewport = await send<{
+            result: {
+              value: { width: number; height: number; clientWidth: number; clientHeight: number };
+            };
+          }>(
+            "Runtime.evaluate",
+            {
+              expression:
+                "({ width: innerWidth, height: innerHeight, clientWidth: document.documentElement.clientWidth, clientHeight: document.documentElement.clientHeight })",
+              returnByValue: true,
+            },
+            sessions[1],
+          );
+          for (const dimension of ["Width", "Height"] as const) {
+            const occupied =
+              childViewport.result.value[dimension === "Width" ? "width" : "height"] -
+              childViewport.result.value[`client${dimension}`];
+            if (
+              configuration.scrollbars === "both" ||
+              configuration.scrollbars === (dimension === "Width" ? "vertical" : "horizontal")
+            )
+              expect(occupied).toBeGreaterThan(0);
+            else expect(occupied).toBe(0);
+          }
           const facts = await captureObservationFacts(cdp, 1);
           expect(facts.issues).toEqual([]);
-          for (const frame of frames) {
-            const node = facts.documents
-              .find((doc) => doc.frame.frameId === frame.frameId)
-              ?.domNodes.find((node) => node.attrs.id === "probe");
-            expect(node, `missing probe in ${names.get(frame.frameId) || "root"}`).toBeDefined();
-            const local = oracles.get(frame.frameId)!.probe;
-            const top = { ...local };
-            let current = frame;
-            while (current.parentFrameId) {
-              const owner = oracles.get(current.parentFrameId)!.owners[names.get(current.frameId)!];
-              top.x = owner.x + top.x * owner.scale;
-              top.y = owner.y + top.y * owner.scale;
-              top.w *= owner.scale;
-              top.h *= owner.scale;
-              current = frames.find((item) => item.frameId === current.parentFrameId)!;
-            }
-            expect(
-              node!.rect,
-              JSON.stringify({
-                frame: names.get(frame.frameId),
-                local,
-                top,
-                viewport: facts.viewport,
-              }),
-            ).not.toBeNull();
-            for (const key of ["x", "y", "w", "h"] as const) {
-              expect(
-                Math.abs(node!.localRect![key] - local[key]),
-                `${names.get(frame.frameId)} local ${key}`,
-              ).toBeLessThan(2);
-              expect(
-                Math.abs(node!.rect![key] - top[key]),
-                `${names.get(frame.frameId)} top ${key}`,
-              ).toBeLessThan(2);
-            }
-          }
           expect(calls.filter((call) => call.endsWith(":Page.getLayoutMetrics"))).toHaveLength(
             sessions.length,
           );
+          // Identity verification also uses Runtime.evaluate; count the full viewport reads separately.
+          const viewportReadsBeforeLive = calls.filter((call) => call.endsWith(":viewport-size"));
+          expect(new Set(viewportReadsBeforeLive).size).toBe(viewportReadsBeforeLive.length);
+          expect(viewportReadsBeforeLive.length).toBeLessThanOrEqual(sessions.length - 1);
+          for (const frame of frames) {
+            for (const [id, local] of Object.entries(oracles.get(frame.frameId)!.probes)) {
+              const node = facts.documents
+                .find((doc) => doc.frame.frameId === frame.frameId)
+                ?.domNodes.find((node) => node.attrs.id === id);
+              expect(node, `missing ${id} in ${names.get(frame.frameId) || "root"}`).toBeDefined();
+              let top = clip(local, oracles.get(frame.frameId)!.viewport);
+              let current = frame;
+              while (top && current.parentFrameId) {
+                const parentOracle = oracles.get(current.parentFrameId)!;
+                const owner = parentOracle.owners[names.get(current.frameId)!];
+                top = clip(
+                  {
+                    x: owner.x + top.x * owner.scale,
+                    y: owner.y + top.y * owner.scale,
+                    w: top.w * owner.scale,
+                    h: top.h * owner.scale,
+                  },
+                  parentOracle.viewport,
+                );
+                current = frames.find((item) => item.frameId === current.parentFrameId)!;
+              }
+              for (const key of ["x", "y", "w", "h"] as const)
+                expect(
+                  Math.abs(node!.localRect![key] - local[key]),
+                  `${names.get(frame.frameId)} ${id} local ${key}`,
+                ).toBeLessThan(2);
+              if (!top) {
+                expect(node!.rect, `${id} must be clipped out`).toBeNull();
+                if (configuration.fixture === "oopif-scrollbars")
+                  expect(
+                    await resolveNodeGeometry(cdp, 1, {
+                      target: frame.target,
+                      frameId: frame.frameId,
+                      backendNodeId: node!.backendNodeId,
+                    }),
+                  ).toMatchObject({ code: "permission_denied" });
+                continue;
+              }
+              expect(node!.rect).not.toBeNull();
+              for (const key of ["x", "y", "w", "h"] as const)
+                expect(
+                  Math.abs(node!.rect![key] - top[key]),
+                  `${names.get(frame.frameId)} ${id} top ${key}`,
+                ).toBeLessThan(2);
+              if (configuration.fixture !== "oopif-scrollbars") continue;
+              const live = await resolveNodeGeometry(cdp, 1, {
+                target: frame.target,
+                frameId: frame.frameId,
+                backendNodeId: node!.backendNodeId,
+              });
+              if ("code" in live) throw new Error(live.message);
+              for (const [key, liveKey] of [
+                ["x", "x"],
+                ["y", "y"],
+                ["w", "width"],
+                ["h", "height"],
+              ] as const)
+                expect(
+                  Math.abs(live.topBounds[liveKey] - top[key]),
+                  `${id} live ${key}`,
+                ).toBeLessThan(2);
+              const before = server.snapshot("coordinates").events.length;
+              for (const type of ["mousePressed", "mouseReleased"])
+                await send(
+                  "Input.dispatchMouseEvent",
+                  { type, ...live.actionPoint, button: "left", clickCount: 1 },
+                  rootSession,
+                );
+              await expect
+                .poll(
+                  () =>
+                    server
+                      .snapshot("coordinates")
+                      .events.slice(before)
+                      .some(
+                        (event: { type: string; path: string; data: { probe?: string } }) =>
+                          event.type === "geometry.clicked" &&
+                          event.data.probe === id &&
+                          event.path ===
+                            (frame.parentFrameId
+                              ? names.get(frame.frameId) === "nested"
+                                ? "/oopif-scrollbars/nested"
+                                : "/oopif-scrollbars/frame"
+                              : "/oopif-scrollbars"),
+                      ),
+                  { timeout: 3000 },
+                )
+                .toBe(true);
+            }
+          }
           const metrics = await send<{
             cssVisualViewport: { zoom: number };
             visualViewport: { clientWidth: number };

apps/extension/src/tools/frame-geometry.ts

@@ -161,7 +161,8 @@ export async function resolveNodeGeometry(
         return geometryError(`could not resolve frame geometry for ${address.frameId}`);
       topVisibleRegions = projectRegionToViewport(localRegion, projection);
       if (address.target.sessionId) {
-        const localViewport = projection.edges[0]?.sourceViewport ?? projection.topViewport;
+        const localViewport = await context.viewport(address.target);
+        if (!localViewport) return geometryError("could not resolve target viewport geometry");
         const localVisibleRegions = localRegion
           .map((polygon) =>
             clipPolygon(

apps/extension/src/tools/geometry/frame-context.ts

@@ -9,8 +9,10 @@ import {
   type Polygon,
   type ProjectiveEdge,
   parseCdpQuad,
+  projectPolygon,
   type Quad,
   type Size,
+  viewportPolygon,
 } from "../geometry";
 import { type CdpRunner, sendToCdpTarget } from "../shared";
 import type { CoordinateOwner, CssViewport, SnapshotProjectionResult } from "./coordinate-types";
@@ -67,6 +69,7 @@ export function cssViewport(metrics: LayoutMetrics): CssViewport {
 /** One read-only measurement phase. Discard after scrolling or any later operation. */
 export class GeometryContext {
   private readonly metrics = new Map<string, Promise<LayoutMetrics>>();
+  private readonly frameViewports = new Map<string, Promise<Size | null>>();
   private readonly owners = new Map<string, Promise<Quad | null>>();
   private readonly projections = new Map<string, Promise<GeometryProjection | null>>();
   private readonly snapshotOwners = new Map<string, Promise<{ quad: Quad; size: Size } | null>>();
@@ -157,6 +160,35 @@ export class GeometryContext {
       : null;
   }
 
+  /** The full OOPIF viewport maps to its owner's content quad. Layout metrics
+   * exclude occupied scrollbars and remain the clipping boundary, not the scale. */
+  private frameViewport(target: CdpTarget): Promise<Size | null> {
+    const key = cdpTargetKey(target);
+    let promise = this.frameViewports.get(key);
+    if (!promise) {
+      promise = this.request<{ result?: { value?: Size }; exceptionDetails?: unknown }>(
+        target,
+        "Runtime.evaluate",
+        {
+          expression: "({ width: window.innerWidth, height: window.innerHeight })",
+          returnByValue: true,
+        },
+      ).then(({ result, exceptionDetails }) => {
+        const size = result?.value;
+        return !exceptionDetails &&
+          size &&
+          Number.isFinite(size.width) &&
+          Number.isFinite(size.height) &&
+          size.width > 0 &&
+          size.height > 0
+          ? size
+          : null;
+      });
+      this.frameViewports.set(key, promise);
+    }
+    return promise;
+  }
+
   ownerContent(target: CdpTarget, backendNodeId: number): Promise<Quad | null> {
     const key = `${cdpTargetKey(target)}:${backendNodeId}`;
     let promise = this.owners.get(key);
@@ -342,12 +374,19 @@ export class GeometryContext {
       const parent = frames.get(root.parentFrameId);
       if (!parent || root.ownerBackendNodeId === undefined) return null;
       const destinationQuad = await this.ownerContent(parent.target, root.ownerBackendNodeId);
-      const source = await this.viewport(root.target);
+      if (!destinationQuad) return null;
+      const source = await this.frameViewport(root.target);
+      const visible = await this.viewport(root.target);
       const parentRoot = this.targetRoot(frames, parent);
-      if (!destinationQuad || !source || !parentRoot) return null;
+      if (!source || !visible || !parentRoot) return null;
       const destinationClips = await this.clips(frames, parent, parentRoot);
       if (!destinationClips) return null;
-      edges.push({ sourceViewport: source, destinationQuad, destinationClips });
+      const edge = { sourceViewport: source, destinationQuad, destinationClips };
+      // Keep scrollbar strips clipped at every target boundary, including
+      // intermediate OOPIFs. Project the clip with the same full-viewport scale.
+      if (source.width !== visible.width || source.height !== visible.height)
+        destinationClips.push(projectPolygon(viewportPolygon(visible), edge));
+      edges.push(edge);
       root = parentRoot;
     }
     const topViewport = await this.viewport(root.target);

apps/extension/src/tools/vom/__tests__/capture-coordinator.test.ts

@@ -655,6 +655,7 @@ function childSnapshot(frameId: string, backendNodeId: number) {
 describe("OOPIF capture", () => {
   it("captures and positions multiple OOPIF documents missing from the root snapshot", async () => {
     const sendToTarget = vi.fn(async (target, method) => {
+      if (method === "Runtime.evaluate") return { result: { value: { width: 300, height: 200 } } };
       if (method === "Page.getLayoutMetrics") {
         return {
           visualViewport: { clientWidth: 1000 },

evals/browser/cases/regression/oopif-scrollbars/README.md

@@ -0,0 +1,41 @@
+# OOPIF occupied-scrollbar regression
+
+An iframe's content quad includes its child viewport's scrollbar space, while
+`Page.getLayoutMetrics().cssLayoutViewport` excludes that space. Mapping the latter
+onto the whole quad stretches positions and sizes. The full target-local viewport
+must determine scale; the visible viewport must still clip content at every OOPIF
+boundary and constrain target-local action points.
+
+This fixture alternates loopback hostnames across two nested OOPIFs. It includes
+scrolling, borders, padding, scaled iframe owners, a partially clipped button and
+a fully clipped button. Custom scrollbars occupy different widths and heights.
+The `scrollbars` query parameter accepts `both` (default), `vertical`, `horizontal`
+or `none`.
+
+Run the numerical regression with Node 22+ and a local Chrome executable:
+
+```sh
+BSK_GEOMETRY_CHROME=/path/to/chrome pnpm --filter @browser-skill/extension exec vitest run \
+  src/tools/__tests__/snapshot-coordinates.browser.test.ts
+```
+
+The existing browser runner is shared with the snapshot-unit regression. The test:
+
+- Verifies actual OOPIF targets and occupied scrollbar dimensions.
+- Compares snapshot and live geometry with independent DOM rectangles and clipping.
+- Dispatches real root-target clicks and verifies the intended frame/button received them.
+- Rejects fully clipped controls and checks snapshot measurement reuse per target.
+- Covers five device-scale/browser-zoom combinations plus single-axis and no-scrollbar cases.
+
+The runner creates and removes isolated browser profiles. It is opt-in and skipped
+in normal unit runs when `BSK_GEOMETRY_CHROME` is unset.
+
+Run the CLI fixture smoke with a connected test extension:
+
+```sh
+BSK_AUTO_UPDATE=off pnpm eval:browser smoke --case oopif-scrollbars --bsk ./target/debug/bsk
+```
+
+The smoke assertions verify both nested frames have occupied scrollbars, that the
+marker is observed and that the session is closed. Numeric geometry and actual
+click assertions are exercised by the browser test above, not by smoke alone.

evals/browser/cases/regression/oopif-scrollbars/oopif-scrollbars.case.json

@@ -0,0 +1,39 @@
+{
+  "$schema": "../../../schemas/case.schema.json",
+  "schemaVersion": 1,
+  "id": "oopif-scrollbars",
+  "title": "Nested OOPIFs with occupied scrollbars and clipped controls",
+  "suite": "regression",
+  "tags": ["geometry", "iframe", "scroll"],
+  "fixture": { "startPath": "/oopif-scrollbars" },
+  "prompts": {
+    "en": "Open {url}, observe the page and its frames, report the OOPIF-SCROLLBARS marker, then close the session.",
+    "zh-CN": "打开 {url}，观察页面及其 iframe，报告 OOPIF-SCROLLBARS 标记，然后关闭会话。"
+  },
+  "coverage": ["session.start", "session.stop", "page.navigate", "inspect.observe"],
+  "assertions": {
+    "site": [
+      {
+        "label": "nested frame fixture settled",
+        "type": "geometry.ready",
+        "where": { "data.root": true },
+        "minCount": 1
+      },
+      {
+        "label": "both child frames have occupied scrollbars",
+        "type": "geometry.scrollbars",
+        "where": { "data.vertical": true, "data.horizontal": true },
+        "minCount": 2
+      }
+    ],
+    "response": [{ "label": "observed the fixture marker", "includes": "OOPIF-SCROLLBARS" }],
+    "adapter": [{ "label": "browser session was closed", "key": "sessionStopped" }]
+  },
+  "smoke": {
+    "steps": [
+      { "action": "navigate" },
+      { "action": "wait-site-event", "type": "geometry.ready", "where": { "root": true } },
+      { "action": "observe" }
+    ]
+  }
+}

evals/browser/cases/regression/oopif-scrollbars/oopif-scrollbars.fixture.mjs

@@ -0,0 +1,56 @@
+import { page, withRun } from "../../../lib/fixtures.mjs";
+
+export default {
+  id: "oopif-scrollbars",
+  routes: ["/oopif-scrollbars", "/oopif-scrollbars/frame", "/oopif-scrollbars/nested"],
+  render({ pathname, runId, query }) {
+    const root = pathname === "/oopif-scrollbars";
+    const nested = pathname.endsWith("/nested");
+    const mode = query.get("scrollbars") ?? "both";
+    return page({
+      title: "OOPIF scrollbar geometry regression",
+      body: `
+        <style>
+          main { margin: 0; width: auto; }
+          body { width: 2000px; height: 2400px; }
+          html { overflow-anchor: none; }
+          ${!root ? `html { overflow-x: ${mode === "vertical" || mode === "none" ? "hidden" : "scroll"}; overflow-y: ${mode === "horizontal" || mode === "none" ? "hidden" : "scroll"}; } html::-webkit-scrollbar { width: 17px; height: 11px; }` : ""}
+          button { position: absolute; padding: 0; border: 0; border-radius: 0; }
+          #probe { left: ${root ? 180 : nested ? 30 : 100}px; top: ${root ? 360 : nested ? 40 : 160}px; width: 60px; height: 20px; }
+          #edge { position: fixed; right: -20px; bottom: -15px; width: 80px; height: 60px; }
+          #outside { position: fixed; left: calc(100% + 2px); top: calc(100% + 2px); width: 10px; height: 10px; }
+          iframe { position: absolute; box-sizing: content-box; width: 420px; height: 320px;
+            left: 340px; top: 400px; border: 6px solid black; padding: 8px; transform: scale(1.2); transform-origin: 0 0; }
+          #nested { left: 150px; top: 210px; width: 200px; height: 120px; border-width: 4px; padding: 6px; transform: scale(0.8); }
+        </style>
+        <button id="probe" data-geometry-probe>OOPIF-SCROLLBARS</button>
+        ${!root ? '<button id="edge" data-geometry-probe>EDGE</button><button id="outside" data-geometry-probe>OUTSIDE</button>' : ""}
+        ${!nested ? `<iframe id="${root ? "cross" : "nested"}" name="${root ? "cross" : "nested"}" title="${root ? "outer" : "nested"} cross-site frame"></iframe>` : ""}
+      `,
+      script: `
+        history.scrollRestoration = "manual";
+        const child = document.querySelector("iframe");
+        if (child) {
+          const url = new URL(${JSON.stringify(withRun(root ? "/oopif-scrollbars/frame" : "/oopif-scrollbars/nested", runId, { scrollbars: mode }))}, location.href);
+          url.hostname = location.hostname === "127.0.0.1" ? "localhost" : "127.0.0.1";
+          child.src = url.href;
+        }
+        document.addEventListener("click", event => {
+          const probe = event.target.closest("[data-geometry-probe]");
+          if (probe) browserEval.send("geometry.clicked", { probe: probe.id });
+        });
+        window.addEventListener("load", () => {
+          scrollTo(${root ? "80, 240" : nested ? "10, 20" : "40, 100"});
+          requestAnimationFrame(() => requestAnimationFrame(() => {
+            document.documentElement.dataset.geometryReady = "true";
+            if (!${root}) browserEval.send("geometry.scrollbars", {
+              vertical: innerWidth > document.documentElement.clientWidth,
+              horizontal: innerHeight > document.documentElement.clientHeight,
+            });
+            browserEval.send("geometry.ready", { root: ${root} });
+          }));
+        });
+      `,
+    });
+  },
+};

evals/browser/cases/regression/snapshot-coordinates/README.md

@@ -33,12 +33,9 @@ BSK_AUTO_UPDATE=off pnpm eval:browser smoke --case snapshot-coordinates --bsk ./
 Smoke alone does **not** certify coordinate accuracy; CLI observations do not expose raw boxes.
 Use the geometric test above for the regression's numeric assertions.
 
-## Separate existing boundary
+## Related scrollbar regression
 
-The OOPIF root uses non-occupying scrollbars in the unit-conversion regression. Root and
-same-process frames retain normal scrollbars. Append `&classic-scrollbars` to the fixture URL
-to reproduce the separate existing OOPIF projection issue: `targetProjection()` maps the CSS
-layout viewport (which excludes occupying scrollbars) onto the entire owner content quad.
-This inflates the projected coordinates when scrollbars occupy space. Main already has that
-mapping; fixing it also changes shared live geometry and is outside this snapshot-unit fix.
-The test does not relax its numeric tolerance to absorb that error.
+The unit-conversion fixture keeps non-occupying OOPIF scrollbars by default. The same
+browser test also runs the dedicated [OOPIF scrollbar fixture](../oopif-scrollbars/README.md),
+which covers occupied scrollbars, two OOPIF boundaries, clipping and real clicks.
+Append `&classic-scrollbars` to this fixture's URL to enable its normal OOPIF scrollbars.

evals/browser/tests/eval.test.mjs

@@ -41,22 +41,23 @@ test("case manifests are discovered, ordered, and grouped into suites", () => {
       "diagnostics",
       "mobile-emulation",
       "generated-form",
+      "oopif-scrollbars",
       "snapshot-coordinates",
     ],
   );
   assert.deepEqual(repositorySummary(cases, fixtureRegistry).suites, {
     core: 6,
     matrix: 1,
-    regression: 1,
+    regression: 2,
   });
 });
 
 test("repository validation links every case to a fixture and valid workflow evidence", () => {
   assert.deepEqual(validateRepositoryCases(cases, fixtureRegistry), []);
   const summary = repositorySummary(cases, fixtureRegistry);
-  assert.equal(summary.cases, 8);
-  assert.equal(summary.fixtureModules, 9);
-  assert.equal(summary.fixtureRoutes, 15);
+  assert.equal(summary.cases, 9);
+  assert.equal(summary.fixtureModules, 10);
+  assert.equal(summary.fixtureRoutes, 18);
 });
 
 test("manifest validation rejects unknown operations and incomplete workflow steps", () => {

install.ps1

@@ -38,11 +38,17 @@ function Write-Die {
 # ── Platform / architecture detection ─────────────────────────────────────────
 
 function Get-PlatformTriple {
-    $arch = [System.Runtime.InteropServices.RuntimeInformation]::ProcessArchitecture
+    # RuntimeInformation.ProcessArchitecture can be unavailable in Windows PowerShell 5.1.
+    # WOW64 exposes the native architecture separately from the 32-bit process.
+    $arch = $env:PROCESSOR_ARCHITEW6432
+    if (-not $arch) { $arch = $env:PROCESSOR_ARCHITECTURE }
+    if (-not $arch) {
+        Write-Die "could not detect Windows architecture: PROCESSOR_ARCHITEW6432 and PROCESSOR_ARCHITECTURE are empty"
+    }
 
     switch ($arch) {
-        "X64"  { $archId = "x64" }
-        "Arm64" { $archId = "arm64" }
+        "AMD64" { $archId = "x64" }
+        "ARM64" { $archId = "arm64" }
         default { Write-Die "unsupported architecture: $arch (x64 and ARM64 only)" }
     }
 
@@ -67,25 +73,21 @@ function Add-ToUserPath {
 
     $currentUserPath = @([Environment]::GetEnvironmentVariable("PATH", "User") -split ";" | Where-Object { $_ })
 
-    if ($currentUserPath -contains $Dir) {
-        Write-Log "$Dir is already in your user PATH"
+    $newUserPath = (@($Dir) + @($currentUserPath | Where-Object { $_ -ine $Dir })) -join ";"
+    if (($currentUserPath -join ";") -ceq $newUserPath) {
+        Write-Log "$Dir is already first in your user PATH"
         return
     }
 
-    $newUserPath = ($currentUserPath + $Dir) -join ";"
     [Environment]::SetEnvironmentVariable("PATH", $newUserPath, "User")
-    Write-Log "added ${Dir} to user PATH"
+    Write-Log "placed ${Dir} first in user PATH"
 }
 
 function Add-ToSessionPath {
     param([string]$Dir)
 
-    $pathEntries = $env:PATH -split ";" | Where-Object { $_ }
-    if ($pathEntries -contains $Dir) {
-        return
-    }
-
-    $env:PATH = "$Dir;$env:PATH"
+    $pathEntries = @($env:PATH -split ";" | Where-Object { $_ -and $_ -ine $Dir })
+    $env:PATH = (@($Dir) + $pathEntries) -join ";"
 }
 
 # ── Git Bash (bash environment) PATH helper ──────────────────────────────────
@@ -126,14 +128,19 @@ function Install-Binary {
     $staged = "$Target.install-$([Guid]::NewGuid().ToString('N'))"
     try {
         [System.IO.File]::Copy($Source, $staged)
+        # The running daemon may come from another installation directory.
+        # Use the downloaded CLI: older versions have broken Windows liveness checks.
+        # Stop verifies daemon identity and uses the current BSK_HOME.
+        # Fail closed for both new installs and replacements; never discard daemon metadata here.
+        & $Source daemon stop
+        if ($LASTEXITCODE -ne 0) {
+            $daemonHome = if ($env:BSK_HOME) { $env:BSK_HOME } else { Join-Path $HOME ".bsk" }
+            $daemonInfoPath = $ExecutionContext.SessionState.Path.GetUnresolvedProviderPathFromPSPath((Join-Path $daemonHome "daemon.json"))
+            throw "could not stop bsk daemon; installation was not changed. Stop any running bsk daemon, remove '$daemonInfoPath', then retry the installer."
+        }
         if ([System.IO.File]::Exists($Target)) {
-            # Use the downloaded CLI: older versions have broken Windows
-            # liveness checks. Stop verifies daemon identity before terminating it.
-            & $Source daemon stop
-            if ($LASTEXITCODE -ne 0) { throw "could not stop bsk daemon; existing installation was not replaced" }
             # PowerShell 5.1 converts $null to an empty path for string parameters.
             [System.IO.File]::Replace($staged, $Target, [NullString]::Value)
-            Write-Log "daemon will restart automatically on the next browser command"
         }
         else {
             [System.IO.File]::Move($staged, $Target)
@@ -166,14 +173,20 @@ function Main {
         Write-Log "latest version is ${version}"
     }
 
+    $platformKey = $platform.PlatformKey
+    $asset = $null
+    if ($manifest -and $manifest.assets) {
+        $asset = $manifest.assets.$platformKey
+    }
+    # ARM64 is not in the current release matrix. Require a published entry
+    # before attempting it, while preserving legacy x64 installs without a manifest.
+    if ($platform.ArchId -eq "arm64" -and -not $asset) {
+        Write-Die "version.json does not list a Windows ARM64 package for bsk $version"
+    }
+
     $archiveName = "bsk-v${version}-$($platform.TargetTriple).zip"
     $downloadUrl = "${GitHub}/releases/download/${tag}/${archiveName}"
-
-    $expectedSha = $null
-    $platformKey = $platform.PlatformKey
-    if ($manifest -and $manifest.assets) {
-        $expectedSha = $manifest.assets.$platformKey.sha256
-    }
+    $expectedSha = if ($asset) { $asset.sha256 } else { $null }
     if (-not $expectedSha) {
         if (-not $manifest) {
             Write-Log "warning: could not fetch version.json; skipping checksum verification"
@@ -184,17 +197,21 @@ function Main {
     }
 
     $tempDir = Join-Path ([System.IO.Path]::GetTempPath()) ([System.IO.Path]::GetRandomFileName())
-    New-Item -ItemType Directory -Path $tempDir -Force | Out-Null
+    [System.IO.Directory]::CreateDirectory($tempDir) | Out-Null
 
     try {
         $archivePath = Join-Path $tempDir $archiveName
 
         Write-Log "downloading ${downloadUrl}"
-        Invoke-WebRequest -Uri $downloadUrl -OutFile $archivePath -UseBasicParsing -ErrorAction Stop
+        # PowerShell 5.1's -OutFile treats brackets as wildcards. Write raw HTTP bytes literally.
+        $response = Invoke-WebRequest -Uri $downloadUrl -UseBasicParsing -ErrorAction Stop
+        try {
+            [System.IO.File]::WriteAllBytes($archivePath, $response.RawContentStream.ToArray())
+        } finally { $response.RawContentStream.Dispose() }
 
         if ($expectedSha) {
             Write-Log "verifying checksum"
-            $actualSha = (Get-FileHash -Algorithm SHA256 -Path $archivePath).Hash
+            $actualSha = (Get-FileHash -Algorithm SHA256 -LiteralPath $archivePath).Hash
             if ($actualSha -ieq $expectedSha) {
                 Write-Log "checksum OK"
             }
@@ -204,15 +221,15 @@ function Main {
         }
 
         Write-Log "extracting ${archiveName}"
-        Expand-Archive -Path $archivePath -DestinationPath $tempDir -Force
+        # PowerShell 5.1's Expand-Archive treats the destination as a wildcard path.
+        Add-Type -AssemblyName System.IO.Compression.FileSystem
+        [System.IO.Compression.ZipFile]::ExtractToDirectory($archivePath, $tempDir)
 
-        if (-not (Test-Path (Join-Path $tempDir "bsk.exe"))) {
+        if (-not (Test-Path -LiteralPath (Join-Path $tempDir "bsk.exe"))) {
             Write-Die "bsk.exe not found in archive"
         }
 
-        if (-not (Test-Path $InstallDir)) {
-            New-Item -ItemType Directory -Path $InstallDir -Force | Out-Null
-        }
+        [System.IO.Directory]::CreateDirectory($InstallDir) | Out-Null
 
         Install-Binary -Source (Join-Path $tempDir "bsk.exe") -Target (Join-Path $InstallDir "bsk.exe")
 
@@ -232,12 +249,18 @@ function Main {
         & $bskPath --version
         if ($LASTEXITCODE -ne 0) { throw "installed bsk failed verification" }
 
+        $command = Get-Command bsk -ErrorAction SilentlyContinue
+        if (-not $command -or $command.CommandType -ne "Application" -or $command.Source -ine $bskPath) {
+            Write-Log "warning: 'bsk' does not resolve to $bskPath in this session; check Get-Command bsk -All for a conflicting command"
+        }
+
         Write-Log "done"
         Write-Host ""
-        Write-Host "Open a new terminal (PowerShell / Git Bash) for PATH changes to take full effect."
+        Write-Host "This PATH check covers the current session only; a new terminal may prefer a Machine PATH entry or alias."
+        Write-Host "In a new PowerShell terminal, run Get-Command bsk -All and confirm the first result is $bskPath."
     }
     finally {
-        Remove-Item -Recurse -Force $tempDir -ErrorAction SilentlyContinue
+        Remove-Item -LiteralPath $tempDir -Recurse -Force -ErrorAction SilentlyContinue
     }
 }
 

scripts/install-windows.test.ps1

@@ -1,8 +1,11 @@
 #Requires -Version 5.1
-param([string]$BskPath = (Join-Path $PSScriptRoot "../target/debug/bsk.exe"))
+param(
+    [string]$BskPath = (Join-Path $PSScriptRoot "../target/debug/bsk.exe"),
+    [switch]$HelpersOnly
+)
 $ErrorActionPreference = "Stop"
 
-# Load definitions, never Main: no downloads or changes to the real user PATH.
+# Load definitions without running Main. Registry PATH writes are isolated below.
 $installer = Join-Path $PSScriptRoot "../install.ps1"
 $tokens = $null
 $errors = $null
@@ -21,27 +24,88 @@ foreach ($statement in $ast.EndBlock.Statements) {
 function Assert-Equal($Actual, $Expected) {
     if ($Actual -cne $Expected) { throw "expected [$Expected], got [$Actual]" }
 }
-function Assert-Fails([scriptblock]$Action) {
+function Assert-Fails([scriptblock]$Action, [string]$MessageContains) {
     $failed = $false
-    try { & $Action } catch { $failed = $true }
+    try { & $Action } catch {
+        $failed = $true
+        if ($MessageContains -and -not $_.Exception.Message.Contains($MessageContains)) { throw }
+    }
     if (-not $failed) { throw "expected failure" }
 }
 
+# Isolate the fatal-error stub and restore the real process environment.
+& {
+    function Write-Die([string]$Message) { throw $Message }
+    $oldProcessArch = $env:PROCESSOR_ARCHITECTURE
+    $oldNativeArch = $env:PROCESSOR_ARCHITEW6432
+    try {
+        $cases = @(
+            @{ Process = 'AMD64'; Native = $null; Arch = 'x64'; Triple = 'x86_64-pc-windows-msvc' }
+            @{ Process = 'ARM64'; Native = $null; Arch = 'arm64'; Triple = 'aarch64-pc-windows-msvc' }
+            @{ Process = 'amd64'; Native = $null; Arch = 'x64'; Triple = 'x86_64-pc-windows-msvc' }
+            @{ Process = 'x86'; Native = 'AMD64'; Arch = 'x64'; Triple = 'x86_64-pc-windows-msvc' }
+            @{ Process = 'x86'; Native = 'ARM64'; Arch = 'arm64'; Triple = 'aarch64-pc-windows-msvc' }
+            @{ Process = $null; Native = 'AMD64'; Arch = 'x64'; Triple = 'x86_64-pc-windows-msvc' }
+            @{ Process = 'x86'; Native = $null; Error = 'unsupported architecture: x86 (x64 and ARM64 only)' }
+            @{ Process = 'AMD64'; Native = 'IA64'; Error = 'unsupported architecture: IA64 (x64 and ARM64 only)' }
+            @{ Process = $null; Native = $null; Error = 'could not detect Windows architecture: PROCESSOR_ARCHITEW6432 and PROCESSOR_ARCHITECTURE are empty' }
+        )
+        foreach ($case in $cases) {
+            $env:PROCESSOR_ARCHITECTURE = $case.Process
+            $env:PROCESSOR_ARCHITEW6432 = $case.Native
+            if ($case.Error) {
+                $message = $null
+                try { Get-PlatformTriple | Out-Null } catch { $message = $_.Exception.Message }
+                Assert-Equal $message $case.Error
+            }
+            else {
+                $platform = Get-PlatformTriple
+                Assert-Equal $platform.ArchId $case.Arch
+                Assert-Equal $platform.TargetTriple $case.Triple
+                Assert-Equal $platform.PlatformKey "windows-$($case.Arch)"
+            }
+        }
+        Write-Host "Windows installer architecture regressions passed ($($PSVersionTable.PSVersion))"
+    }
+    finally {
+        $env:PROCESSOR_ARCHITECTURE = $oldProcessArch
+        $env:PROCESSOR_ARCHITEW6432 = $oldNativeArch
+    }
+}
 $dir = 'C:\Users\Alice\.local\bin'
-foreach ($existing in @('', 'C:\WindowsApps', 'C:\A;C:\B')) {
-    $script:UserPath = $existing
-    Add-ToUserPath $dir
-    $expected = if ($existing) { "$existing;$dir" } else { $dir }
-    Assert-Equal $script:UserPath $expected
-    Add-ToUserPath $dir
-    Assert-Equal $script:UserPath $expected
+$pathCases = @(
+    @{ Existing = ''; Expected = $dir }
+    @{ Existing = 'C:\WindowsApps'; Expected = "$dir;C:\WindowsApps" }
+    @{ Existing = 'C:\A;C:\B'; Expected = "$dir;C:\A;C:\B" }
+    @{ Existing = "C:\old-bsk;$dir;C:\B;$($dir.ToUpperInvariant())"; Expected = "$dir;C:\old-bsk;C:\B" }
+)
+$oldPath = $env:PATH
+try {
+    foreach ($case in $pathCases) {
+        $script:UserPath = $case.Existing
+        $env:PATH = $case.Existing
+        foreach ($attempt in 1..2) {
+            Add-ToUserPath $dir
+            Add-ToSessionPath $dir
+            Assert-Equal $script:UserPath $case.Expected
+            Assert-Equal $env:PATH $case.Expected
+        }
+    }
+} finally { $env:PATH = $oldPath }
+if ($HelpersOnly) {
+    Write-Host "Windows installer helper regressions passed ($($PSVersionTable.PSVersion))"
+    return
 }
 
 $root = Join-Path ([IO.Path]::GetTempPath()) ("bsk-install-test-" + [Guid]::NewGuid().ToString('N'))
 [IO.Directory]::CreateDirectory($root) | Out-Null
 $oldBskHome = $env:BSK_HOME
 $oldAutoUpdate = $env:BSK_AUTO_UPDATE
+$oldVersion = $env:BSK_VERSION
+$oldProcessArch = $env:PROCESSOR_ARCHITECTURE
+$oldNativeArch = $env:PROCESSOR_ARCHITEW6432
 $daemon = $null
+$script:DownloadServer = $null
 try {
     $utf8 = New-Object System.Text.UTF8Encoding($false)
     $bashRc = Join-Path $root ".bashrc"
@@ -66,7 +130,7 @@ try {
     if ($LASTEXITCODE -ne 0) { throw "Git Bash failed" }
     Assert-Equal $actual ('/c' + $special.Substring(2).Replace('\', '/'))
 
-    $env:BSK_HOME = Join-Path $root "home"
+    $env:BSK_HOME = Join-Path $root "home [state]"
     $env:BSK_AUTO_UPDATE = "off"
     [IO.Directory]::CreateDirectory($env:BSK_HOME) | Out-Null
     $sourceDir = Join-Path $root "download"
@@ -76,7 +140,8 @@ try {
     $targetDir = Join-Path $root "中文 space [x] & install"
     [IO.Directory]::CreateDirectory($targetDir) | Out-Null
     $target = Join-Path $targetDir "bsk.exe"
-    Install-Binary $source $target
+    $firstInstallOutput = Install-Binary $source $target 6>&1 | Out-String
+    if ($firstInstallOutput -match 'daemon will restart') { throw 'fresh install reported a daemon restart' }
     Assert-Equal (Get-FileHash -LiteralPath $target).Hash (Get-FileHash -LiteralPath $source).Hash
 
     $daemon = Start-Process -FilePath $target -ArgumentList @('daemon', 'start', '--foreground', '--port', '0') -WindowStyle Hidden -PassThru
@@ -99,18 +164,165 @@ try {
     & $target --version
     if ($LASTEXITCODE -ne 0) { throw "replacement is not executable" }
 
+    # Installing into a new directory must also stop a daemon from the old one.
+    $newTargetDir = Join-Path $root "new install"
+    [IO.Directory]::CreateDirectory($newTargetDir) | Out-Null
+    $newTarget = Join-Path $newTargetDir "bsk.exe"
+    $before = (Get-FileHash -LiteralPath $target).Hash
+    $daemon = Start-Process -FilePath $target -ArgumentList @('daemon', 'start', '--foreground', '--port', '0') -WindowStyle Hidden -PassThru
+    $deadline = [DateTime]::UtcNow.AddSeconds(15)
+    while (-not [IO.File]::Exists($infoPath)) {
+        if ($daemon.HasExited -or [DateTime]::UtcNow -gt $deadline) { throw "old-directory daemon failed to start" }
+        Start-Sleep -Milliseconds 50
+    }
+    Install-Binary $source $newTarget
+    if (-not $daemon.WaitForExit(5000)) { throw "new-directory install left the old daemon running" }
+    Assert-Equal (Get-FileHash -LiteralPath $target).Hash $before
+    Assert-Equal (Get-FileHash -LiteralPath $newTarget).Hash (Get-FileHash -LiteralPath $source).Hash
+    & $newTarget --version
+    if ($LASTEXITCODE -ne 0) { throw "new-directory installation is not executable" }
+    if (@(Get-ChildItem -LiteralPath $newTargetDir -Filter "*.install-*").Count) { throw "new-directory staging files leaked" }
+
     # Refuse replacement when daemon identity cannot be verified.
     [IO.File]::WriteAllText($infoPath, 'invalid daemon metadata')
     $before = (Get-FileHash -LiteralPath $target).Hash
-    Assert-Fails { Install-Binary $source $target }
+    Assert-Fails { Install-Binary $source $target } -MessageContains $infoPath
     Assert-Equal (Get-FileHash -LiteralPath $target).Hash $before
+
+    # A failed stop must also prevent installation to a previously empty target.
+    $blockedTarget = Join-Path $newTargetDir "blocked.exe"
+    Assert-Fails { Install-Binary $source $blockedTarget } -MessageContains $infoPath
+    if (Test-Path -LiteralPath $blockedTarget) { throw "failed stop created an installation" }
+    if (@(Get-ChildItem -LiteralPath $newTargetDir -Filter "*.install-*").Count) { throw "failed stop leaked staging files" }
+    Assert-Equal ([IO.File]::ReadAllText($infoPath)) 'invalid daemon metadata'
+    # Following the reported recovery path must allow the same installation to succeed.
     [IO.File]::Delete($infoPath)
+    Install-Binary $source $blockedTarget
+    Assert-Equal (Get-FileHash -LiteralPath $blockedTarget).Hash (Get-FileHash -LiteralPath $source).Hash
 
     # A remaining lock must fail without truncation or staging debris.
     $lock = [IO.File]::Open($target, [IO.FileMode]::Open, [IO.FileAccess]::Read, [IO.FileShare]::None)
     try { Assert-Fails { Install-Binary $source $target } } finally { $lock.Dispose() }
     Assert-Equal (Get-FileHash -LiteralPath $target).Hash $before
     if (@(Get-ChildItem -LiteralPath $targetDir -Filter "*.install-*").Count) { throw "staging files leaked" }
+
+    # Exercise Main with real ZIPs/executables, isolating network and user state.
+    & {
+        $fixtureTemp = Join-Path $root 'temp [literal]'
+        [IO.Directory]::CreateDirectory($fixtureTemp) | Out-Null
+        $mainDefinition = ($ast.EndBlock.Statements | Where-Object {
+            $_ -is [System.Management.Automation.Language.FunctionDefinitionAst] -and $_.Name -eq 'Main'
+        }).Extent.Text.Replace('[System.IO.Path]::GetTempPath()', '$fixtureTemp')
+        Invoke-Expression $mainDefinition
+        function Write-Die([string]$Message) { throw $Message }
+        $bashProfile = (Get-Command Add-ToBashProfile).ScriptBlock
+        function Add-ToBashProfile([string]$Dir) {
+            & $bashProfile $Dir (Join-Path $root 'flow.bashrc')
+        }
+        $fixtureArchive = Join-Path $root 'release.zip'
+        Compress-Archive -LiteralPath $source -DestinationPath $fixtureArchive -CompressionLevel Fastest
+        # Serve the ZIP over loopback HTTP. Only the URL is redirected below;
+        # Invoke-WebRequest and the installer's disk writes remain real.
+        $script:DownloadServer = Start-Job -ArgumentList $fixtureArchive -ScriptBlock {
+            param($Archive)
+            $ErrorActionPreference = 'Stop'
+            $body = [IO.File]::ReadAllBytes($Archive)
+            $listener = [Net.Sockets.TcpListener]::new([Net.IPAddress]::Loopback, 0)
+            try {
+                $listener.Start()
+                Write-Output $listener.LocalEndpoint.Port
+                while ($true) {
+                    if (-not $listener.Pending()) { Start-Sleep -Milliseconds 50; continue }
+                    $client = $listener.AcceptTcpClient()
+                    try {
+                        $stream = $client.GetStream()
+                        $stream.ReadTimeout = 5000
+                        $stream.WriteTimeout = 5000
+                        $reader = [IO.StreamReader]::new($stream)
+                        while (($line = $reader.ReadLine()) -and $line.Length) { }
+                        $header = [Text.Encoding]::ASCII.GetBytes("HTTP/1.1 200 OK`r`nContent-Type: application/octet-stream`r`nContent-Length: $($body.Length)`r`nConnection: close`r`n`r`n")
+                        $stream.Write($header, 0, $header.Length)
+                        $stream.Write($body, 0, $body.Length)
+                    } finally { $client.Dispose() }
+                }
+            } finally { $listener.Stop() }
+        }
+        $serverPort = $null
+        $deadline = [DateTime]::UtcNow.AddSeconds(15)
+        while (-not $serverPort) {
+            $serverPort = Receive-Job $script:DownloadServer
+            if ($script:DownloadServer.State -ne 'Running' -or [DateTime]::UtcNow -gt $deadline) {
+                throw 'download fixture failed to start'
+            }
+            if (-not $serverPort) { Start-Sleep -Milliseconds 50 }
+        }
+        $asset = @{ sha256 = (Get-FileHash -LiteralPath $fixtureArchive).Hash }
+        $fixtureManifest = @{ version = '9.8.7'; assets = @{ 'windows-x64' = $asset } }
+        $downloads = New-Object 'System.Collections.Generic.List[string]'
+        function Invoke-RestMethod([string]$Uri) {
+            if (-not $fixtureManifest) { throw 'fixture manifest unavailable' }
+            return $fixtureManifest
+        }
+        function Invoke-WebRequest {
+            [CmdletBinding()]
+            param([string]$Uri, [string]$OutFile, [switch]$UseBasicParsing)
+            $downloads.Add($Uri)
+            $PSBoundParameters['Uri'] = "http://127.0.0.1:$serverPort/release.zip"
+            Microsoft.PowerShell.Utility\Invoke-WebRequest @PSBoundParameters -TimeoutSec 15
+        }
+        $GitHub = 'https://example.invalid/fixture'
+        $InstallDir = Join-Path $root 'installed [literal]'
+        $installed = Join-Path $InstallDir 'bsk.exe'
+        $env:BSK_VERSION = $null
+        $env:PROCESSOR_ARCHITECTURE = 'AMD64'
+        $env:PROCESSOR_ARCHITEW6432 = $null
+        $script:UserPath = "$targetDir;$InstallDir;$($InstallDir.ToUpperInvariant())"
+        $env:PATH = "$targetDir;$InstallDir;$oldPath"
+        Assert-Equal (Get-Command bsk).Source $target
+        $installOutput = Main 6>&1 | Out-String
+        if ($installOutput -notmatch 'current session only' -or
+            $installOutput -notmatch 'Machine PATH' -or $installOutput -notmatch 'Get-Command bsk -All') {
+            throw 'install did not explain PATH verification in a new terminal'
+        }
+        Assert-Equal $downloads.Count 1
+        Assert-Equal (Get-Command bsk).Source $installed
+        Assert-Equal $script:UserPath "$InstallDir;$targetDir"
+        Assert-Equal (Get-FileHash -LiteralPath $installed).Hash (Get-FileHash -LiteralPath $source).Hash
+        Assert-Equal @(Get-ChildItem -LiteralPath $fixtureTemp -Force).Count 0
+
+        # ARM64 must be listed in the manifest before any archive is requested.
+        $env:PROCESSOR_ARCHITECTURE = 'ARM64'
+        $downloads.Clear()
+        $message = $null
+        try { Main } catch { $message = $_.Exception.Message }
+        Assert-Equal $message 'version.json does not list a Windows ARM64 package for bsk 9.8.7'
+        Assert-Equal $downloads.Count 0
+        $env:BSK_VERSION = '9.8.7'
+        $fixtureManifest = $null
+        $message = $null
+        try { Main } catch { $message = $_.Exception.Message }
+        Assert-Equal $message 'version.json does not list a Windows ARM64 package for bsk 9.8.7'
+        Assert-Equal $downloads.Count 0
+
+        # Keep pinned x64 installs compatible with older releases without manifests.
+        $env:PROCESSOR_ARCHITECTURE = 'AMD64'
+        Main
+        Assert-Equal $downloads.Count 1
+        Assert-Equal @(Get-ChildItem -LiteralPath $fixtureTemp -Force).Count 0
+
+        # A listed ARM64 archive remains selectable (the fixture uses the host EXE).
+        $fixtureManifest = @{ version = '9.8.7'; assets = @{ 'windows-arm64' = $asset } }
+        $env:PROCESSOR_ARCHITECTURE = 'ARM64'
+        Main
+        Assert-Equal $downloads[$downloads.Count - 1] "$GitHub/releases/download/cli-v9.8.7/bsk-v9.8.7-aarch64-pc-windows-msvc.zip"
+
+        # A checksum failure must clean the bracketed temp path and preserve the install.
+        $before = (Get-FileHash -LiteralPath $installed).Hash
+        $fixtureManifest.assets['windows-arm64'] = @{ sha256 = '0' * 64 }
+        Assert-Fails { Main }
+        Assert-Equal (Get-FileHash -LiteralPath $installed).Hash $before
+        Assert-Equal @(Get-ChildItem -LiteralPath $fixtureTemp -Force).Count 0
+    }
     Write-Host "Windows installer regressions passed ($($PSVersionTable.PSVersion))"
 }
 catch {
@@ -119,12 +331,20 @@ catch {
     throw
 }
 finally {
+    if ($script:DownloadServer) {
+        Stop-Job $script:DownloadServer
+        Remove-Job $script:DownloadServer
+    }
     if ($daemon -and -not $daemon.HasExited) {
         Stop-Process -Id $daemon.Id -Force
         $daemon.WaitForExit(5000) | Out-Null
     }
     $env:BSK_HOME = $oldBskHome
     $env:BSK_AUTO_UPDATE = $oldAutoUpdate
+    $env:BSK_VERSION = $oldVersion
+    $env:PROCESSOR_ARCHITECTURE = $oldProcessArch
+    $env:PROCESSOR_ARCHITEW6432 = $oldNativeArch
+    $env:PATH = $oldPath
     Remove-Item Env:BSK_TEST_RC -ErrorAction SilentlyContinue
     # Resolve and verify before recursive cleanup; only this fixture is removed.
     $resolvedRoot = [IO.Path]::GetFullPath($root)