chore: v2.8.43 — terminal glyphs stay sharp in every pane; a huge diff line no longer hides the rest

v2.8.42 reacted to a page merge by toggling the font family on the next
frame, so each renderer re-acquired an atlas. Panes still showed squeezed,
overlapping glyphs: the toggle lands a frame late, swaps every pane onto a
fresh atlas (or onto one another pane already toggled to), and a page added
without a merge shifts nothing yet still raced it.

addon-webgl 0.20 fixes the root cause with globally monotonic page versions.
Do the same on 0.19: whenever the shared atlas adds, removes or merges a page,
give every page a version no texture slot has uploaded, synchronously, so
every renderer on that atlas re-uploads all pages before it draws again.
When the page comes back from the background, restamp and repaint. An addon
of another shape keeps the old font-toggle fallback.

client/src/components/HtmlFrame.tsx

@@ -15,8 +15,10 @@ import { FileText, Loader2 } from "lucide-react";
 import { artifactDocument, frameSandbox } from "../lib/artifactView";
 import { blobText, inlineHtml, type FetchFile } from "../lib/htmlInline";
 
-/** A page read by `fetchFile` is shown up to this size. */
-const HTML_MAX = 10 * 1024 * 1024;
+/** A page read by `fetchFile` is shown up to this size. A self-contained
+ *  page (a slide deck with its video and images inlined as base64) is easily
+ *  past 10 MB; the iframe renders far larger documents than this. */
+const HTML_MAX = 64 * 1024 * 1024;
 
 export function HtmlFrame({
   path,

client/src/components/lanes/LaneDiffView.tsx

@@ -179,6 +179,18 @@ export function langFor(filePath: string) {
 }
 
 /** Tokenized line text. `emph` marks the span that actually changed. */
+/** The tail of a row the server cut down (`LaneDiffLine.elided`). */
+function Elided({ n }: { n?: number }) {
+  const { t, i18n } = useTranslation("lanes");
+  if (!n) return null;
+  const size = new Intl.NumberFormat(i18n.language, { notation: "compact" }).format(n);
+  return (
+    <span className="ml-1 select-none rounded bg-surface-3 px-1 font-sans text-[10px] text-fg-muted">
+      {t("changes.lineElided", { size })}
+    </span>
+  );
+}
+
 function Code({ text, lang, emph }: { text: string; lang: string; emph?: [number, number] }) {
   if (emph) {
     const [from, to] = emph;
@@ -544,6 +556,7 @@ function UnifiedLine({
           {line.type === "add" ? "+" : line.type === "del" ? "-" : " "}
         </span>
         <Code text={line.text} lang={lang} emph={emph} />
+        <Elided n={line.elided} />
       </span>
       {bar && <HunkBar change={bar} />}
     </Row>
@@ -621,6 +634,7 @@ function SplitLine({
       />
       <span className="whitespace-pre px-1">
         {line ? <Code text={line.text} lang={lang} emph={e} /> : null}
+        {line ? <Elided n={line.elided} /> : null}
       </span>
       {bar && <HunkBar change={bar} />}
     </Row>

client/src/components/lanes/__tests__/LaneDiffView.test.tsx

@@ -609,3 +609,26 @@ describe("LaneDiffView — line comments", () => {
     expect(screen.queryByTestId("diff-comment-line-1")).toBeNull();
   });
 });
+
+describe("LaneDiffView — a row the server cut down", () => {
+  const CUT: LaneChangeFile = {
+    ...FILE,
+    hunks: [
+      {
+        ...FILE.hunks![0]!,
+        lines: [
+          { type: "del", oldLine: 1, newLine: null, text: '<video src="AAAA', elided: 3_000_000 },
+          { type: "add", oldLine: null, newLine: 1, text: '<video src="BBBB', elided: 3_000_000 },
+        ],
+      },
+    ],
+  };
+
+  it("says how much of the row it hides, in both layouts", () => {
+    const { unmount } = render(<LaneDiffView file={CUT} layout="unified" />);
+    expect(screen.getAllByText(/3M more characters on this line/)).toHaveLength(2);
+    unmount();
+    render(<LaneDiffView file={CUT} layout="split" />);
+    expect(screen.getAllByText(/3M more characters on this line/)).toHaveLength(2);
+  });
+});

client/src/components/run/TerminalView.tsx

@@ -96,6 +96,36 @@ type DropState = "hint" | "paste" | "uploading" | "failed" | "tooBig" | "tooBigL
 /** localStorage flag for xterm's screen-reader mode (a Settings toggle can set it later). */
 export const SCREEN_READER_KEY = "agenthub.terminal.screenReader";
 /** localStorage flag: the "Shift+drag selects text" hint was dismissed. */
+/** The atlas a WebGL addon draws from: @xterm/addon-webgl 0.19 keeps these
+ *  fields unminified in its build. Undefined on any other shape. */
+type AtlasPages = { pages: { version: number }[] };
+const atlasOf = (addon: WebglAddon): AtlasPages | undefined => {
+  const atlas = (addon as unknown as { _renderer?: { _charAtlas?: AtlasPages } })._renderer
+    ?._charAtlas;
+  return Array.isArray(atlas?.pages) ? atlas : undefined;
+};
+/** Last version handed out by `restampAtlas`, shared by every pane. */
+let atlasStamp = 0;
+/**
+ * Gives every page of the addon's glyph atlas a version no texture slot has
+ * uploaded, so EVERY renderer sharing that atlas re-uploads every page from
+ * its canvas on its next draw — what addon-webgl 0.20 does with globally
+ * monotonic page versions. 0.19 counts per page, so after a merge shifts the
+ * pages down a slot can hold a stale page whose counter happens to match, and
+ * glyphs are sampled squeezed or foreign. Steps of 2^24 stay clear of the
+ * per-glyph increments a page makes before the next restamp. False when the
+ * addon is not the shape this knows.
+ */
+const restampAtlas = (addon: WebglAddon): boolean => {
+  const atlas = atlasOf(addon);
+  if (!atlas) return false;
+  for (const page of atlas.pages) {
+    atlasStamp += 2 ** 24;
+    page.version = atlasStamp;
+  }
+  return true;
+};
+
 const SELECT_HINT_KEY = "agenthub.terminal.selectHintSeen";
 const readFlag = (key: string) => {
   try {
@@ -763,31 +793,40 @@ export const TerminalView = memo(function TerminalView({
       };
       document.fonts?.addEventListener("loadingdone", onFontLoaded);
       // @xterm/addon-webgl 0.19 shares ONE glyph atlas between every terminal
-      // with the same font, and when it fills up it merges four pages into one
-      // larger page and shifts the rest down. A GPU texture is re-uploaded only
-      // when its page's `version` differs from the uploaded one, and after a
-      // shift those counters can coincide, so a slot keeps a stale page of
-      // another size: every glyph is sampled squeezed or foreign while the
-      // buffer stays correct (fixed upstream only in 0.20 betas). Any option
-      // change makes each renderer re-acquire its atlas and re-upload all pages,
-      // so this toggles the family's trailing space (as onFontLoaded does) on
-      // a merge. `clearTextureAtlas` is no fix: it empties the SHARED atlas
+      // with the same font. When it fills up it merges four pages into one
+      // larger page and shifts the rest down, and a GPU texture is re-uploaded
+      // only when its page's `version` differs from the uploaded one — after a
+      // shift those per-page counters can coincide, so a slot keeps a stale
+      // page of another size and every glyph is drawn squeezed or foreign
+      // while the buffer stays correct (fixed upstream only in 0.20 betas).
+      // Any change to the page list therefore restamps every page's version
+      // (`restampAtlas`) synchronously, before the next draw of ANY pane on
+      // that atlas. `clearTextureAtlas` is no fix: it empties the SHARED atlas
       // but redraws only this pane, leaving its siblings slicing reused space.
+      // An addon of another shape falls back to toggling the family's
+      // trailing space on the next frame, which makes each renderer re-acquire
+      // its atlas (as onFontLoaded does).
       let atlasFrame = 0;
       const rebuildAtlas = () => {
-        if (atlasFrame) return;
+        if (gpu && restampAtlas(gpu)) return true;
+        if (atlasFrame) return false;
         // Never inside the render that is rasterizing the merging glyph.
         atlasFrame = requestAnimationFrame(() => {
           atlasFrame = 0;
           const family = term.options.fontFamily ?? "";
           term.options.fontFamily = family.endsWith(" ") ? family.trimEnd() : `${family} `;
         });
+        return false;
       };
       const atlasMerged = gpu?.onRemoveTextureAtlasCanvas(rebuildAtlas);
+      const atlasGrew = gpu?.onAddTextureAtlasCanvas(rebuildAtlas);
       // The browser may also drop the textures without a context-loss event
-      // (sleep/resume, a long-backgrounded tab): rebuild when the page is back.
+      // (sleep/resume, a long-backgrounded tab): re-upload when the page is
+      // back, and repaint, since nothing else asks this pane to draw.
       const onPageShown = () => {
-        if (document.visibilityState === "visible") rebuildAtlas();
+        if (document.visibilityState === "visible" && rebuildAtlas()) {
+          term.refresh(0, term.rows - 1);
+        }
       };
       document.addEventListener("visibilitychange", onPageShown);
       window.addEventListener("focus", onPageShown);
@@ -811,6 +850,7 @@ export const TerminalView = memo(function TerminalView({
         document.fonts?.removeEventListener("loadingdone", onFontLoaded);
         if (atlasFrame) cancelAnimationFrame(atlasFrame);
         atlasMerged?.dispose();
+        atlasGrew?.dispose();
         document.removeEventListener("visibilitychange", onPageShown);
         window.removeEventListener("focus", onPageShown);
         window.removeEventListener(FONT_SIZE_EVENT, onFontPref);

client/src/components/run/__tests__/TerminalView.test.tsx

@@ -63,6 +63,9 @@ const termState = {
 };
 const onResizeHandlers: Array<() => void> = [];
 const termOptions: { theme?: unknown } = {};
+const refreshMock = vi.fn();
+/** The atlas the next WebGL addon draws from; null = an addon of another shape. */
+const nextAtlas: { pages: { version: number }[] | null } = { pages: null };
 const ctorArgs: Array<{ theme?: unknown }> = [];
 
 vi.mock("@xterm/xterm", () => ({
@@ -92,6 +95,7 @@ vi.mock("@xterm/xterm", () => ({
       return { dispose: vi.fn() };
     },
     dispose: disposeMock,
+    refresh: refreshMock,
     loadAddon: loadAddonMock,
     attachCustomWheelEventHandler: wheelHandlerMock,
     attachCustomKeyEventHandler: keyHandlerMock,
@@ -113,7 +117,12 @@ vi.mock("@xterm/addon-fit", () => ({
 }));
 // The newest WebGL addon, with the context-loss listener the view gave it.
 const gpu: {
-  last: { dispose: ReturnType<typeof vi.fn>; lose: () => void; merge: () => void } | null;
+  last: {
+    dispose: ReturnType<typeof vi.fn>;
+    lose: () => void;
+    merge: () => void;
+    grow: () => void;
+  } | null;
 } = {
   last: null,
 };
@@ -121,8 +130,10 @@ vi.mock("@xterm/addon-webgl", () => ({
   WebglAddon: vi.fn().mockImplementation(() => {
     let onLoss = () => {};
     let onMerge = () => {};
+    let onGrow = () => {};
     const addon = {
       __webgl: true,
+      ...(nextAtlas.pages ? { _renderer: { _charAtlas: { pages: nextAtlas.pages } } } : {}),
       dispose: vi.fn(),
       onContextLoss: (fn: () => void) => {
         onLoss = fn;
@@ -132,8 +143,17 @@ vi.mock("@xterm/addon-webgl", () => ({
         onMerge = fn;
         return { dispose: vi.fn() };
       },
+      onAddTextureAtlasCanvas: (fn: () => void) => {
+        onGrow = fn;
+        return { dispose: vi.fn() };
+      },
+    };
+    gpu.last = {
+      dispose: addon.dispose,
+      lose: () => onLoss(),
+      merge: () => onMerge(),
+      grow: () => onGrow(),
     };
-    gpu.last = { dispose: addon.dispose, lose: () => onLoss(), merge: () => onMerge() };
     return addon;
   }),
 }));
@@ -495,9 +515,37 @@ describe("TerminalView", () => {
     expect(disposeMock).not.toHaveBeenCalled(); // the terminal itself lives on
   });
 
+  it("restamps every atlas page at once when the page list changes", () => {
+    // addon-webgl 0.19 counts versions per page, so after a merge shifts the
+    // pages a texture slot can keep a stale page whose counter matches. Every
+    // page gets a version no slot has uploaded — in every pane on the atlas.
+    const pages = [{ version: 3 }, { version: 7 }, { version: 1 }];
+    nextAtlas.pages = pages;
+    const raf = vi.spyOn(window, "requestAnimationFrame");
+    try {
+      render(<TerminalView runId="agenthub-lane-1" wsBaseUrl="ws://localhost:4820" />);
+      gpu.last!.merge();
+      const first = pages.map((p) => p.version);
+      expect(new Set(first).size).toBe(3);
+      expect(first.every((v) => v > 7)).toBe(true);
+      gpu.last!.grow();
+      expect(pages.every((p, i) => p.version > Math.max(...first) && p.version !== first[i])).toBe(
+        true
+      );
+      expect(raf).not.toHaveBeenCalled(); // synchronous, before any pane draws
+      // The page coming back re-uploads and repaints this pane.
+      refreshMock.mockClear();
+      window.dispatchEvent(new Event("focus"));
+      expect(refreshMock).toHaveBeenCalledWith(0, 27);
+    } finally {
+      nextAtlas.pages = null;
+      raf.mockRestore();
+    }
+  });
+
   it("re-acquires the glyph atlas on the next frame after a page merge", () => {
-    // addon-webgl 0.19 may keep a stale page in a GPU slot after it merges
-    // atlas pages; any option change makes it re-upload every page.
+    // An addon whose atlas this cannot reach: any option change makes each
+    // renderer re-acquire its atlas and re-upload every page.
     const raf = vi.spyOn(window, "requestAnimationFrame").mockImplementation(() => 1);
     render(<TerminalView runId="agenthub-lane-1" wsBaseUrl="ws://localhost:4820" />);
     const opts = termOptions as { fontFamily?: string };

client/src/i18n/locales/en/lanes.json

@@ -92,6 +92,7 @@
   "changes.expandFile": "Expand {{path}}",
   "changes.fileGone": "That file no longer has changes in this range.",
   "changes.fileTruncated": "Diff cut short — open the file in an editor for the rest.",
+  "changes.lineElided": "… {{size}} more characters on this line",
   "changes.commentLine": "Comment on line {{n}} — pasted into this workspace's pane",
   "changes.commentOn": "Comment on {{at}} — pasted into the pane you used last; nothing is sent until you press Enter there",
   "changes.commentSend": "Paste into pane",

client/src/i18n/locales/vi/lanes.json

@@ -92,6 +92,7 @@
   "changes.expandFile": "Mở {{path}}",
   "changes.fileGone": "File này không còn thay đổi nào trong phạm vi đang xem.",
   "changes.fileTruncated": "Diff bị cắt bớt — mở file trong editor để xem phần còn lại.",
+  "changes.lineElided": "… còn {{size}} ký tự trên dòng này",
   "changes.commentLine": "Comment dòng {{n}} — dán vào pane của workspace này",
   "changes.commentOn": "Comment {{at}} — dán vào pane bạn dùng gần nhất; chưa gửi gì cho tới khi bạn nhấn Enter ở đó",
   "changes.commentSend": "Dán vào pane",

client/src/lib/types.ts

@@ -2974,6 +2974,9 @@ export interface LaneDiffLine {
   /** Line number on the right (after) side; null on a removed line. */
   newLine: number | null;
   text: string;
+  /** Characters cut off the end of a very long row (a base64 blob, a minified
+   *  bundle): `text` holds only its start. Absent on a whole row. */
+  elided?: number;
 }
 
 /** `GET /api/lanes/:id/git/blame` — Annotate: who last changed each line of

client/src/pages/__tests__/__snapshots__/screens.snapshot.test.tsx.snap

@@ -7316,7 +7316,7 @@ exports[`screen snapshots > Settings — about 1`] = `
                 <span
                   class="text-status-warning/90"
                 >
-                  UI build v2.8.42 (rebuild client to match)
+                  UI build v2.8.43 (rebuild client to match)
                 </span>
               </p>
             </div>

docs/API.md

@@ -817,6 +817,11 @@ that file.
 - Three caps guard the response: **300** files listed, **200 KB** of patch per
   file, **1 MB** of patch in a `full` read. A cap that bit sets `truncated` on
   the response and on the file it cut.
+- A row longer than **4,000** characters (an inlined base64 image or video, a
+  minified bundle) comes back cut to its first 1,000 with `elided: <characters
+  hidden>`, BEFORE the per-file cap is applied, so one huge line no longer eats
+  the hunks after it. Each file's raw patch is read up to 16 M characters; past
+  that it is still `truncated`.
 - Read-only, no same-origin guard. `available: false` (HTTP **200**) for a cwd
   git cannot read; `range=branch` compares against the workspace's base branch,
   else the repo's default branch (what `origin/HEAD` names, else `main`/`master`)

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "agenthub",
-  "version": "2.8.42",
+  "version": "2.8.43",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "agenthub",
-      "version": "2.8.42",
+      "version": "2.8.43",
       "hasInstallScript": true,
       "license": "UNLICENSED",
       "dependencies": {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "agenthub",
-  "version": "2.8.42",
+  "version": "2.8.43",
   "bin": {
     "agenthub": "bin/agenthub.js"
   },

server/__tests__/git-diff-ops-hardening.test.js

@@ -473,6 +473,55 @@ describe("reads larger than the git() buffer report truncated, not missing", ()
   });
 });
 
+describe("a page with megabyte-long lines (inlined base64) keeps every hunk", () => {
+  const blob = (c) => c.repeat(3 * 1024 * 1024); // one 3 MB line
+
+  it("cuts the long rows down and still shows the hunks after them", async () => {
+    const body = (mid, end) =>
+      [
+        "<h1>title</h1>",
+        ...Array.from({ length: 40 }, (_, i) => `row ${i}`),
+        mid,
+        ...Array.from({ length: 40 }, (_, i) => `tail ${i}`),
+        end,
+        "",
+      ].join("\n");
+    write(LANE, "deck.html", body(`<video src="${blob("A")}">`, "<p>old end</p>"));
+    g(LANE, "add", "-A");
+    g(LANE, "commit", "-qm", "deck");
+    write(
+      LANE,
+      "deck.html",
+      body(`<video src="${blob("B")}">`, "<p>new end</p>").replace(
+        "<h1>title</h1>",
+        "<h1>new title</h1>"
+      )
+    );
+    const out = await collectChanges(LANE, { range: "work", file: "deck.html" });
+    const f = out.files[0];
+    assert.equal(f.truncated, undefined);
+    assert.equal(out.truncated, false);
+    const lines = f.hunks.flatMap((h) => h.lines);
+    const long = lines.filter((l) => l.elided);
+    assert.equal(long.length, 2);
+    for (const l of long) {
+      assert.ok(l.text.length < 2000);
+      assert.equal(l.text.length + l.elided, '<video src="'.length + 3 * 1024 * 1024 + 2);
+    }
+    // The change AFTER the 3 MB rows survives: the cap no longer eats it.
+    assert.ok(lines.some((l) => l.type === "add" && l.text === "<p>new end</p>"));
+    assert.ok(lines.some((l) => l.type === "add" && l.text === "<h1>new title</h1>"));
+  });
+
+  it("leaves ordinary rows whole", async () => {
+    write(LANE, "a.txt", "one\nTWO\n");
+    const out = await collectChanges(LANE, { range: "work", file: "a.txt" });
+    const lines = out.files[0].hunks.flatMap((h) => h.lines);
+    assert.ok(lines.every((l) => l.elided === undefined));
+    assert.ok(lines.some((l) => l.text === "TWO"));
+  });
+});
+
 describe("loop 2: secret file at any depth, symlinked .claude", () => {
   const KEY = '{"env":{"ANTHROPIC_API_KEY":"sk-deep"}}';
 

server/__tests__/git-diff-ops.test.js

@@ -203,18 +203,21 @@ describe("collectChanges — work range", () => {
     });
   });
 
-  it("still returns content when a huge file has no newline to cut on", async () => {
-    // A minified bundle is ONE line. Cutting the patch at the last newline
-    // inside the cap would land at index -1 here and hand back an empty
-    // patch — a file changed by a megabyte rendering as "no textual change".
+  it("still returns content when a huge file is one line", async () => {
+    // A minified bundle is ONE line. It used to be cut at the per-file cap
+    // (and, cut at the last newline, could come back empty — a file changed
+    // by a megabyte rendering as "no textual change"); now the row itself is
+    // cut down and says how much it hides, and nothing is truncated.
     const { MAX_FILE_BYTES } = require("../lib/git-diff");
     write(LANE, "min.js", `${"x".repeat(MAX_FILE_BYTES + 5000)}\n`);
     const out = await collectChanges(LANE, { range: "work", file: "min.js" });
     const entry = out.files[0];
-    assert.equal(entry.truncated, true);
-    assert.equal(out.truncated, true);
-    assert.ok(entry.hunks.length > 0, "a truncated patch still carries its hunk");
-    assert.ok(entry.hunks[0].lines[0].text.startsWith("xxx"));
+    assert.equal(entry.truncated, undefined);
+    assert.equal(out.truncated, false);
+    assert.ok(entry.hunks.length > 0, "the patch still carries its hunk");
+    const row = entry.hunks[0].lines.find((l) => l.type === "add");
+    assert.ok(row.text.startsWith("xxx"));
+    assert.equal(row.text.length + row.elided, MAX_FILE_BYTES + 5000);
   });
 
   it("reports a binary file without trying to diff it", async () => {

server/lib/git-diff.js

@@ -61,6 +61,19 @@ async function readCapped(dir, args, capChars) {
 const MAX_FILES = 300;
 /** Most patch bytes read for ONE file before its hunks are cut short. */
 const MAX_FILE_BYTES = 200_000;
+/** Characters of one file's raw patch read before its long lines are cut down
+ *  (`elideLongLines`) and `MAX_FILE_BYTES` applied. A page that embeds a video
+ *  or a font as base64 is a few lines of megabytes each: read at
+ *  `MAX_FILE_BYTES`, its first such line used the whole budget and every hunk
+ *  after it was lost. Past this the patch is still truncated. */
+const MAX_PATCH_READ_CHARS = 16 * 1024 * 1024;
+/** A diff row longer than this is shown cut down to `LONG_LINE_KEEP`
+ *  characters, with how many it hides (`elided` on the parsed line). */
+const LONG_LINE_CHARS = 4000;
+const LONG_LINE_KEEP = 1000;
+/** Ends a cut-down row in the raw patch: a private-use character, then the
+ *  count of characters hidden. `parseUnifiedDiff` turns it into `elided`. */
+const ELIDED_MARK = "\uE000";
 /** Most patch bytes across all files in a `full` (review-mode) response. */
 const MAX_TOTAL_BYTES = 1_000_000;
 /** An untracked file larger than this is reported without content. */
@@ -259,15 +272,23 @@ function parseUnifiedDiff(patch) {
     // row of its own and carries no line number.
     if (raw.startsWith("\\")) continue;
     const marker = raw[0];
-    const text = raw.slice(1);
+    let text = raw.slice(1);
+    // A row `elideLongLines` cut down: the text it kept, and how much it hid.
+    let elided = 0;
+    const cut = text.lastIndexOf(ELIDED_MARK);
+    if (cut >= 0 && /^\d+$/.test(text.slice(cut + 1))) {
+      elided = Number(text.slice(cut + 1));
+      text = text.slice(0, cut);
+    }
+    const extra = elided ? { elided } : {};
     if (marker === "+") {
-      current.lines.push({ type: "add", oldLine: null, newLine: newLine++, text });
+      current.lines.push({ type: "add", oldLine: null, newLine: newLine++, text, ...extra });
     } else if (marker === "-") {
-      current.lines.push({ type: "del", oldLine: oldLine++, newLine: null, text });
+      current.lines.push({ type: "del", oldLine: oldLine++, newLine: null, text, ...extra });
     } else if (marker === " ") {
       // An unchanged EMPTY line is " " — one space, no text. A truly empty
       // string is the tail of the final "\n", not a row.
-      current.lines.push({ type: "ctx", oldLine: oldLine++, newLine: newLine++, text });
+      current.lines.push({ type: "ctx", oldLine: oldLine++, newLine: newLine++, text, ...extra });
     }
   }
   return hunks;
@@ -532,7 +553,27 @@ async function patchFor(dir, { range, baseRef, sha, file, untracked, context })
       : range === "branch"
         ? ["diff", u, `${baseRef}...HEAD`, "--", file]
         : ["diff", u, "HEAD", "--", file];
-  return readCapped(dir, [...args, "--no-color", "--no-ext-diff"], MAX_FILE_BYTES).catch(() => "");
+  return readCapped(dir, [...args, "--no-color", "--no-ext-diff"], MAX_PATCH_READ_CHARS).catch(
+    () => ""
+  );
+}
+
+/**
+ * The patch with every row longer than `LONG_LINE_CHARS` cut down to its first
+ * `LONG_LINE_KEEP` characters plus `ELIDED_MARK` and the count it hides. Only
+ * what the panel SHOWS is cut: the hunk actions (`hunkPatch`, `selectionPatch`)
+ * re-read git's own diff and match hunks by header, which this never changes.
+ */
+function elideLongLines(patch) {
+  if (patch.length <= LONG_LINE_CHARS) return patch;
+  return patch
+    .split("\n")
+    .map((row) =>
+      row.length > LONG_LINE_CHARS && !row.startsWith("@@")
+        ? `${row.slice(0, LONG_LINE_KEEP + 1)}${ELIDED_MARK}${row.length - LONG_LINE_KEEP - 1}`
+        : row
+    )
+    .join("\n");
 }
 
 /**
@@ -648,7 +689,15 @@ async function collectChanges(
         untracked: entry.untracked,
         context: ctx,
       });
+      // A read that hit its own ceiling came back partial: still cut short,
+      // however small eliding its long rows makes it.
+      const partial = patch.length >= MAX_PATCH_READ_CHARS;
+      patch = elideLongLines(patch);
       const cap = Math.min(MAX_FILE_BYTES, budget);
+      if (partial) {
+        entry.truncated = true;
+        truncated = true;
+      }
       if (patch.length > cap) {
         // Cut on a line boundary so the last row is a whole line — but only
         // when that boundary is near the cap. A minified file is one enormous
@@ -1334,6 +1383,7 @@ async function plainTreeAll(dir) {
 }
 
 module.exports = {
+  elideLongLines,
   collectChanges,
   CONFLICT_CODES,
   contentSha,