fix(app): load capped review patches

packages/app/e2e/regression/review-terminal-stacked.spec.ts

@@ -9,12 +9,19 @@ const title = "Review terminal stacked"
 const branchDiffs = [
   fileDiff(".github/actions/setup-bun/action.yml", 7),
   ...Array.from({ length: 2_739 }, (_, index) =>
-    fileDiff(`src/branch/generated-${String(index).padStart(4, "0")}.ts`, 100),
+    fileDiff(
+      `src/branch/d${String(Math.floor(index / 100)).padStart(5, "0")}/generated-${String(index).padStart(4, "0")}.ts`,
+      100,
+      false,
+    ),
   ),
 ]
 
 test("keeps the review tree and terminal sized when both panels are open", async ({ page }) => {
   test.setTimeout(120_000)
+  const events: Array<{ directory: string; payload: Record<string, unknown> }> = []
+  let detailVersion = 1
+  let detailFailures = 1
   await page.setViewportSize({ width: 1400, height: 900 })
   await mockOpenCodeServer(page, {
     directory,
@@ -48,7 +55,10 @@ test("keeps the review tree and terminal sized when both panels are open", async
         time: { created: 1700000000000, updated: 1700000000000 },
       },
     ],
+    sessionStatus: { [sessionID]: { type: "idle" } },
     pageMessages: () => ({ items: [] }),
+    events: () => events.splice(0, 1),
+    eventRetry: 16,
   })
   await page.route(/\/vcs(?:\?.*)?$/, (route) =>
     route.fulfill({
@@ -57,17 +67,25 @@ test("keeps the review tree and terminal sized when both panels are open", async
       body: JSON.stringify({ branch: "review-pane-performance", default_branch: "dev" }),
     }),
   )
-  await page.route("**/vcs/diff**", (route) =>
-    route.fulfill({
+  await page.route("**/vcs/diff**", (route) => {
+    const url = new URL(route.request().url())
+    const scope = url.searchParams.get("directory")?.replaceAll("\\", "/")
+    const detail = scope?.endsWith("/src/branch/d00027")
+    if (detail && detailFailures-- > 0) return route.fulfill({ status: 500, body: "retry detail" })
+    return route.fulfill({
       status: 200,
       contentType: "application/json",
       body: JSON.stringify(
-        new URL(route.request().url()).searchParams.get("mode") === "branch"
-          ? branchDiffs
+        url.searchParams.get("mode") === "branch"
+          ? detail
+            ? branchDiffs
+                .filter((diff) => diff.file.startsWith("src/branch/d00027/"))
+                .map((diff) => fileDiff(diff.file, diff.additions, true, detailVersion))
+            : branchDiffs
           : Array.from({ length: 7 }, (_, index) => fileDiff(`src/git-${index}.ts`, 1)),
       ),
-    }),
-  )
+    })
+  })
   await page.route("**/pty", (route) =>
     route.fulfill({
       status: 200,
@@ -96,7 +114,7 @@ test("keeps the review tree and terminal sized when both panels are open", async
   await expect(page.getByRole("tab", { name: "Review 2740" })).toBeVisible()
   await page.keyboard.press("Control+Backquote")
   await expect(page.locator("#terminal-panel")).toBeVisible()
-  await expectTree(page, 2_745, "action.yml")
+  await expectTree(page, 2_773, "action.yml")
   await expectStackGeometry(page)
 
   const treeViewport = page.locator('#review-panel [data-slot="session-review-v2-sidebar-tree"] .scroll-view__viewport')
@@ -113,41 +131,66 @@ test("keeps the review tree and terminal sized when both panels are open", async
   })
   expect(bottomGap).toBeGreaterThanOrEqual(0)
   expect(bottomGap).toBeLessThanOrEqual(16)
+  const lazyDiff = page.waitForRequest((request) => {
+    const url = new URL(request.url())
+    return (
+      url.pathname === "/vcs/diff" &&
+      url.searchParams.get("directory")?.replaceAll("\\", "/").endsWith("/src/branch/d00027") === true
+    )
+  })
+  await lastFile.click()
+  await lazyDiff
+  const preview = page.locator('[data-slot="session-review-v2-diff-scroll"]')
+  await expect(preview).toContainText("after-1")
+  detailVersion = 2
+  events.push(statusEvent("busy"))
+  await expect(page.getByRole("button", { name: "Stop" })).toBeVisible()
+  const refreshedDiff = page.waitForRequest((request) => {
+    const url = new URL(request.url())
+    return (
+      url.pathname === "/vcs/diff" &&
+      url.searchParams.get("directory")?.replaceAll("\\", "/").endsWith("/src/branch/d00027") === true
+    )
+  })
+  events.push(statusEvent("idle"))
+  await refreshedDiff
+  await expect(preview).toContainText("after-2")
   await selectMode(page, "Branch changes", "Git changes")
   await expectTree(page, 8, "git-0.ts")
+  await page.getByRole("button", { name: "git-0.ts" }).click()
   await selectMode(page, "Git changes", "Branch changes")
-  await expectTree(page, 2_745, "action.yml")
+  await expectTree(page, 2_773, "action.yml")
 
   const filter = page.getByRole("searchbox", { name: "Filter files" })
   await filter.fill("generated-2738")
   await expectTree(page, 1, "generated-2738.ts")
   await filter.fill("")
-  await expectTree(page, 2_745, "action.yml")
+  await expectTree(page, 2_773, "action.yml")
 
   await page.getByRole("button", { name: "Toggle file tree" }).click()
   await expect(page.locator('[data-slot="session-review-v2-sidebar"]')).toHaveAttribute("aria-hidden", "true")
   await expect(page.locator('#review-panel [data-component="file-tree-v2"]')).toHaveCount(1)
   await page.getByRole("button", { name: "Toggle file tree" }).click()
-  await expectTree(page, 2_745, "action.yml")
+  await expectTree(page, 2_773, "action.yml")
 
   await page.keyboard.press("Control+Backquote")
   await expect(page.locator("#terminal-panel")).toHaveCount(0)
-  await expectTree(page, 2_745, "action.yml")
+  await expectTree(page, 2_773, "action.yml")
   await page.keyboard.press("Control+Backquote")
   await expect(page.locator("#terminal-panel")).toBeVisible()
-  await expectTree(page, 2_745, "action.yml")
+  await expectTree(page, 2_773, "action.yml")
 
   await page.getByRole("button", { name: "Toggle review" }).click()
   await expect(page.locator("#review-panel")).toHaveAttribute("aria-hidden", "true")
   await expect(page.locator('#review-panel [data-component="file-tree-v2"]')).toHaveCount(1)
   await page.getByRole("button", { name: "Toggle review" }).click()
-  await expectTree(page, 2_745, "action.yml")
+  await expectTree(page, 2_773, "action.yml")
   await page.setViewportSize({ width: 1_000, height: 700 })
-  await expectTree(page, 2_745, "action.yml")
+  await expectTree(page, 2_773, "action.yml")
   await expectStackGeometry(page)
   await page.setViewportSize({ width: 1_000, height: 120 })
   await page.setViewportSize({ width: 1_400, height: 900 })
-  await expectTree(page, 2_745, "action.yml")
+  await expectTree(page, 2_773, "action.yml")
   await expectStackGeometry(page)
 })
 
@@ -201,12 +244,21 @@ function base64Encode(value: string) {
   return Buffer.from(value, "utf8").toString("base64").replace(/\+/g, "-").replace(/\//g, "_").replace(/=/g, "")
 }
 
-function fileDiff(file: string, additions: number) {
+function statusEvent(type: "busy" | "idle") {
+  return {
+    directory,
+    payload: { type: "session.status", properties: { sessionID, status: { type } } },
+  }
+}
+
+function fileDiff(file: string, additions: number, loaded = true, version = 1) {
   return {
     file,
     additions,
     deletions: 0,
     status: "modified",
-    patch: `diff --git a/${file} b/${file}\n--- a/${file}\n+++ b/${file}\n@@ -1 +1 @@\n-export const value = 'before'\n+export const value = 'after'\n`,
+    patch: loaded
+      ? `diff --git a/${file} b/${file}\n--- a/${file}\n+++ b/${file}\n@@ -1 +1 @@\n-export const value = 'before'\n+export const value = 'after-${version}'\n`
+      : `diff --git a/${file} b/${file}\n--- a/${file}\n+++ b/${file}`,
   }
 }

packages/app/src/pages/session.tsx

@@ -1,4 +1,4 @@
-import type { Project, UserMessage } from "@opencode-ai/sdk/v2"
+import type { Project, UserMessage, VcsFileDiff } from "@opencode-ai/sdk/v2"
 import { useDialog } from "@opencode-ai/ui/context/dialog"
 import { createQuery, skipToken, useMutation, useQueryClient } from "@tanstack/solid-query"
 import {
@@ -76,6 +76,7 @@ import { SessionReviewEmptyChangesV2 } from "@opencode-ai/session-ui/v2/session-
 import { SessionReviewEmptyNoGitV2 } from "@opencode-ai/session-ui/v2/session-review-empty-no-git-v2"
 import { ReviewPanelV2 } from "@/pages/session/v2/review-panel-v2"
 import { createReviewPanelV2State } from "@/pages/session/v2/review-panel-v2-state"
+import { reviewDiffDirectory, reviewDiffNeedsLoad, reviewRootDirectory } from "@/pages/session/v2/review-diff-kinds"
 import { TerminalPanel } from "@/pages/session/terminal-panel"
 import { TerminalPanelV2 } from "@/pages/session/terminal-panel-v2"
 import { useComposerCommands } from "@/pages/session/use-composer-commands"
@@ -651,6 +652,46 @@ export default function Page() {
     if (store.changes === "git" || store.changes === "branch") return !vcsQuery.isPending
     return true
   }
+  const loadReviewDiff = async (file: string, version?: number): Promise<VcsFileDiff | undefined> => {
+    const mode = vcsMode()
+    if (!mode) return
+    const root = reviewRootDirectory(sync().project?.worktree ?? sdk().directory)
+    const directory = reviewDiffDirectory(root, file)
+    const source = reviewDiffs().find((diff) => diff.file === file)
+    const valid = (diff: VcsFileDiff | undefined) => {
+      if (!diff || !source) return
+      if (diff.additions !== source.additions || diff.deletions !== source.deletions) return
+      if (reviewDiffNeedsLoad(diff)) return
+      return diff
+    }
+    const request = (scope: string, context?: number) =>
+      queryClient
+        .fetchQuery({
+          queryKey: [serverSDK().scope, ...vcsKey(), mode, "directory", scope, context, version] as const,
+          staleTime: Number.POSITIVE_INFINITY,
+          retry: 2,
+          queryFn: () =>
+            sdk()
+              .client.vcs.diff({ mode, directory: scope, context })
+              .then((result) => result.data ?? []),
+        })
+        .then((diffs) => diffs.find((diff) => diff.file === file))
+
+    if (directory !== root) {
+      try {
+        const scoped = valid(await request(directory))
+        if (scoped) return scoped
+      } catch (error) {
+        console.debug("[session-review] failed to load scoped vcs diff", { mode, file, directory, error })
+      }
+    }
+    try {
+      const bounded = valid(await request(root, 3))
+      if (bounded) return bounded
+    } catch (error) {
+      console.debug("[session-review] failed to load bounded vcs diff", { mode, file, root, error })
+    }
+  }
 
   const newSessionWorktree = createMemo(() => {
     if (store.newSessionWorktree === "create") return "create"
@@ -1182,6 +1223,10 @@ export default function Page() {
     },
     diffs: reviewDiffs,
     diffsReady: reviewReady,
+    get diffVersion() {
+      return vcsQuery.dataUpdatedAt
+    },
+    loadDiff: loadReviewDiff,
     get activeFile() {
       return tree.activeDiff
     },

packages/app/src/pages/session/v2/review-diff-kinds.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, test } from "bun:test"
-import { filterReviewFiles, reviewDiffKinds } from "./review-diff-kinds"
+import { filterReviewFiles, reviewDiffDirectory, reviewDiffKinds, reviewDiffNeedsLoad } from "./review-diff-kinds"
 
 describe("reviewDiffKinds", () => {
   test("maps file and directory kinds", () => {
@@ -28,3 +28,43 @@ describe("filterReviewFiles", () => {
     expect(filterReviewFiles(files, "")).toEqual(files)
   })
 })
+
+describe("reviewDiffNeedsLoad", () => {
+  test("loads changed files whose aggregate patch has no hunks", () => {
+    expect(
+      reviewDiffNeedsLoad({
+        file: "src/a.ts",
+        additions: 1,
+        deletions: 0,
+        patch: "diff --git a/src/a.ts b/src/a.ts\n--- a/src/a.ts\n+++ b/src/a.ts",
+      }),
+    ).toBe(true)
+  })
+
+  test("keeps complete patches and empty changes", () => {
+    expect(
+      reviewDiffNeedsLoad({
+        file: "src/a.ts",
+        additions: 1,
+        deletions: 0,
+        patch: "@@ -0,0 +1 @@\n+value",
+      }),
+    ).toBe(false)
+    expect(reviewDiffNeedsLoad({ file: "empty.txt", additions: 0, deletions: 0 })).toBe(false)
+  })
+})
+
+describe("reviewDiffDirectory", () => {
+  test("scopes nested files to their parent directory", () => {
+    expect(reviewDiffDirectory("/repo", "src/lib/a.ts")).toBe("/repo/src/lib")
+    expect(reviewDiffDirectory("C:\\repo", "src/lib/a.ts")).toBe("C:\\repo\\src\\lib")
+  })
+
+  test("does not rescope root files", () => {
+    expect(reviewDiffDirectory("/repo/", "README.md")).toBe("/repo")
+    expect(reviewDiffDirectory("/", "README.md")).toBe("/")
+    expect(reviewDiffDirectory("C:\\", "README.md")).toBe("C:\\")
+    expect(reviewDiffDirectory("/", "src/a.ts")).toBe("/src")
+    expect(reviewDiffDirectory("C:\\", "src/a.ts")).toBe("C:\\src")
+  })
+})

packages/app/src/pages/session/v2/review-diff-kinds.ts

@@ -12,6 +12,24 @@ export function filterRenderableDiff(value: SnapshotFileDiff | VcsFileDiff): val
   return typeof value.file === "string"
 }
 
+export function reviewDiffNeedsLoad(diff: RenderDiff) {
+  if (diff.additions === 0 && diff.deletions === 0) return false
+  return !diff.patch || !/^@@ /m.test(diff.patch)
+}
+
+export function reviewRootDirectory(root: string) {
+  return root === "/" || /^[A-Za-z]:[/\\]?$/.test(root) ? root : root.replace(/[/\\]+$/, "")
+}
+
+export function reviewDiffDirectory(root: string, file: string) {
+  const path = normalizePath(file)
+  const index = path.lastIndexOf("/")
+  const separator = root.includes("\\") ? "\\" : "/"
+  const base = reviewRootDirectory(root)
+  if (index < 0) return base
+  return `${base.endsWith(separator) ? base : base + separator}${path.slice(0, index).replaceAll("/", separator)}`
+}
+
 export function reviewDiffKinds(diffs: RenderDiff[]) {
   const merge = (a: Kind | undefined, b: Kind) => {
     if (!a) return b

packages/app/src/pages/session/v2/review-panel-v2.tsx

@@ -1,4 +1,4 @@
-import { createMemo, createSignal, Show, type JSX } from "solid-js"
+import { createMemo, createResource, createSignal, Show, type JSX } from "solid-js"
 import type { SnapshotFileDiff, VcsFileDiff } from "@opencode-ai/sdk/v2"
 import {
   SESSION_REVIEW_V2_SIDEBAR_WIDTH_MAX,
@@ -25,6 +25,7 @@ import {
   filterRenderableDiff,
   filterReviewFiles,
   reviewDiffKinds,
+  reviewDiffNeedsLoad,
   type RenderDiff,
 } from "@/pages/session/v2/review-diff-kinds"
 import type { ReviewPanelV2State } from "@/pages/session/v2/review-panel-v2-state"
@@ -37,6 +38,8 @@ export type ReviewPanelV2Props = {
   empty?: JSX.Element
   diffs: () => ReviewDiff[]
   diffsReady: () => boolean
+  diffVersion?: number
+  loadDiff?: (path: string, version?: number) => Promise<RenderDiff | undefined>
   activeFile?: string
   onSelectFile: (path: string) => void
   diffStyle: SessionReviewDiffStyle
@@ -74,7 +77,26 @@ export function ReviewPanelV2(props: ReviewPanelV2Props) {
     if (active && files.includes(active)) return active
     return files[0]
   })
-  const activeItem = createMemo(() => diffs().find((diff) => diff.file === activeDiff()))
+  const sourceActiveItem = createMemo(() => diffs().find((diff) => diff.file === activeDiff()))
+  const detailSource = createMemo(() => {
+    const diff = sourceActiveItem()
+    const load = props.loadDiff
+    if (!diff || !load || !reviewDiffNeedsLoad(diff)) return
+    return { diff, load, version: props.diffVersion }
+  })
+  const [loadedDiff] = createResource(detailSource, async ({ diff, load, version }) => {
+    const value = await load(diff.file, version)
+    if (value?.file !== diff.file) return
+    return { source: diff, version, value }
+  })
+
+  const activeItem = createMemo(() => {
+    const source = sourceActiveItem()
+    if (loadedDiff.state !== "ready") return source
+    const loaded = loadedDiff()
+    if (loaded && loaded.source === source && loaded.version === props.diffVersion) return loaded.value
+    return source
+  })
 
   const readFile = async (path: string) =>
     sdk()