diff --git a/.changeset/cli-revert-rendering.md b/.changeset/cli-revert-rendering.md
new file mode 100644
index 000000000..a007bf471
--- /dev/null
+++ b/.changeset/cli-revert-rendering.md
@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/kimi-code": patch
+---
+
+Revert the recent TUI transcript rendering changes to the original upstream behavior while rendering issues are reworked.
diff --git a/.changeset/pi-tui-revert-rendering.md b/.changeset/pi-tui-revert-rendering.md
new file mode 100644
index 000000000..6787bb507
--- /dev/null
+++ b/.changeset/pi-tui-revert-rendering.md
@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/pi-tui": patch
+---
+
+Revert the fork's viewport and scrollback rendering patches, restoring the upstream differential-rendering behavior. The narrow-terminal fixes (width clamping, overwide-line truncation) are kept.
diff --git a/.changeset/web-thinking-effort-levels.md b/.changeset/web-thinking-effort-levels.md
index 247088c19..71c58f3a5 100644
--- a/.changeset/web-thinking-effort-levels.md
+++ b/.changeset/web-thinking-effort-levels.md
@@ -1,5 +1,5 @@
 ---
-"@moonshot-ai/kimi-code": minor
+"@moonshot-ai/kimi-code": patch
 ---
 
 Add a segmented thinking-level control in the web model picker for models that support multiple reasoning efforts. Open the composer model menu to choose a level.
diff --git a/packages/pi-tui/AGENTS.md b/packages/pi-tui/AGENTS.md
index 924f5f13c..500e9627b 100644
--- a/packages/pi-tui/AGENTS.md
+++ b/packages/pi-tui/AGENTS.md
@@ -1,6 +1,6 @@
 # pi-tui Agent Guide
 
-`packages/pi-tui` is a vendored copy of pi-tui from the upstream pi-mono project (baseline: upstream 0.80.2, see commit `7859b0af`). It is no longer patched via pnpm patches — all local fixes are applied directly to the source.
+`packages/pi-tui` is a vendored copy of pi-tui from the upstream pi-mono project (baseline: upstream 0.80.2, see commit `7859b0af`). It is no longer patched via pnpm patches — all local fixes are applied directly to the source. The differential-rendering behavior in `src/tui.ts` matches upstream: the fork's viewport/scrollback rendering patches were reverted; the only remaining divergences are listed below.
 
 ## Local divergences from upstream (must be preserved on every re-vendor)
 
@@ -17,6 +17,5 @@ Never overwrite this directory wholesale when syncing from upstream. Each of the
 
 ## Testing
 
-- This package's tests run with `node --test` (`pnpm --filter @moonshot-ai/pi-tui test`), not vitest; the root `vitest run` does not execute them — CI covers them through the dedicated `test-pi-tui` job in `.github/workflows/ci.yml`. The `test` script runs both `test/*.test.ts` and `e2e/*.test.ts`; `test:e2e` runs the e2e cases alone.
+- This package's tests run with `node --test` (`pnpm --filter @moonshot-ai/pi-tui test`), not vitest; the root `vitest run` does not execute them — CI covers them through the dedicated `test-pi-tui` job in `.github/workflows/ci.yml`.
 - Prefer adding new narrow-width tests to the existing test file of the corresponding component.
-- `e2e/` is a rendering-bug ledger: one case file per production rendering bug, driven end to end through the xterm-emulated `VirtualTerminal` (screen, scrollback, scroll position). When a rendering bug is found, add a `caseNN-*.test.ts` repro there and register it in `e2e/README.md`; keep it as a permanent regression guard after the fix. See `e2e/README.md` for the renderer invariants these cases assert.
diff --git a/packages/pi-tui/e2e/README.md b/packages/pi-tui/e2e/README.md
deleted file mode 100644
index 3c07a2440..000000000
--- a/packages/pi-tui/e2e/README.md
+++ /dev/null
@@ -1,71 +0,0 @@
-# pi-tui rendering e2e cases
-
-This folder is a **bug ledger**: one test file per rendering bug we hit in
-production, driving the real `TUI` against an xterm-emulated terminal
-(`test/virtual-terminal.ts`, backed by `@xterm/headless`). Each case
-reproduces the original failure end to end — screen contents, scrollback,
-scroll position — and stays as a permanent regression guard.
-
-Run with:
-
-```sh
-pnpm --filter @moonshot-ai/pi-tui test:e2e   # e2e cases only
-pnpm --filter @moonshot-ai/pi-tui test        # unit tests + e2e cases
-```
-
-## Background: the rendering model
-
-`TUI.doRender()` renders differentially against a logical line buffer.
-`previousViewportTop` anchors which logical line sits on the top screen row.
-Terminal scrollback is **append-only**: rows enter it only by scrolling off
-the top of the screen, and can never be partially rewritten or truncated.
-That physical constraint drives three invariants the renderer must hold:
-
-1. **Monotonic anchor** — `previousViewportTop` never rewinds (except on a
-   collapse, where the content ends at or above the screen top). Rewinding
-   repaints rows scrollback already holds; the next scroll commits them
-   again, duplicating the span.
-2. **Exactly-once commit** — every row that crosses the viewport top must be
-   scrolled into scrollback exactly once: zero times loses the row, twice
-   duplicates it.
-3. **Cursor bookkeeping sync** — the internal `hardwareCursorRow` must equal
-   the real terminal cursor row at all times; the differential path computes
-   relative moves from it, so any desync writes rows to the wrong place.
-
-Accepted trade-offs (by design, not bugs):
-
-- **Stale bytes**: content that changes above the viewport is not repainted
-  into scrollback; scrollback keeps the old version. This avoids `ESC[3J`,
-  which yanks the scroll position on Windows Terminal (microsoft/Terminal#20370).
-- **Collapse seam**: a collapse rewind re-commits up to one screen of rows;
-  the content changed so drastically there that the seam is not recognizable.
-- **Pinned gap**: a partial shrink keeps the anchor pinned, leaving a bounded
-  blank gap below the input box that the next growth refills.
-
-## Case index
-
-| Case | Symptom | Root cause | Status |
-| --- | --- | --- | --- |
-| [case01](./case01-collapse-blank-screen.test.ts) | Screen mostly blank after a large shrink (compaction), input box gone | Clamped differential path desynced the cursor when content collapsed above the viewport | Fixed (#1315) |
-| [case02](./case02-collapse-scroll-position.test.ts) | Scroll position yanked to the top while reading scrollback (Windows Terminal) | Destructive full redraw emitted `ESC[3J` | Fixed (#1315) |
-| [case03](./case03-full-redraw-residue.test.ts) | Stale text above the welcome banner after `/clear`; duplicated rows after ctrl+o expand | App-level session reset / expansion toggled content wholesale without a forced full redraw | Fixed (#1315, app layer uses `requestRender(true)`) |
-| [case04](./case04-oscillation-duplication.test.ts) | Transcript spans duplicated in scrollback during streaming (shrink/grow oscillation) | Shrink re-anchor rewound the viewport anchor; the next grow re-committed rows scrollback already held | Fixed (#1353) |
-| [case05](./case05-growth-past-anchor-row-loss.test.ts) | Transcript rows missing from scrollback after streaming | Growth past the anchor with an above-viewport change repainted in place without scrolling, so the skipped rows never got committed (invariant 2) | Fixed (#1353, review) |
-| [case06](./case06-cursor-above-pinned-window.test.ts) | Rows written to the wrong screen position after a pinned shrink | `repaintViewport()` positioned the cursor to a logical row above the painted window; `hardwareCursorRow` desynced from the real cursor (invariant 3) | Fixed (#1353, review) |
-
-A case for a not-yet-fixed bug is marked **Open** in the table and is
-expected to fail — it is the executable reproduction. Flip it to Fixed
-when it turns green.
-
-Related unit-level guards (not duplicated here): kitty images straddling the
-viewport top during a collapse are covered in `test/tui-shrink.test.ts`.
-
-## Adding a case
-
-1. Reproduce the bug with `createHarness()` from [harness.ts](./harness.ts):
-   drive frames with `frame(lines)`, then assert on `getViewport()`,
-   `getScrollBuffer()`, `getScrollPosition()`, or captured writes.
-2. Name the file `caseNN-short-slug.test.ts` and add a row to the table
-   above: symptom as the user saw it, root cause, and which invariant broke.
-3. Prefer unique per-line markers (`row-42`) so exactly-once assertions
-   cannot be confused by stale bytes.
diff --git a/packages/pi-tui/e2e/case01-collapse-blank-screen.test.ts b/packages/pi-tui/e2e/case01-collapse-blank-screen.test.ts
deleted file mode 100644
index 602d468c7..000000000
--- a/packages/pi-tui/e2e/case01-collapse-blank-screen.test.ts
+++ /dev/null
@@ -1,59 +0,0 @@
-import assert from "node:assert";
-import { describe, it } from "node:test";
-import { createHarness } from "./harness.ts";
-
-// Case 01 — blank screen / missing input box after a large shrink.
-//
-// Symptom: after context compaction (or any event collapsing the transcript
-// far above the viewport top), the screen went mostly blank and the input
-// box disappeared; typing produced no visible feedback.
-//
-// Root cause: the differential path clamped the first changed line to the
-// viewport but then rendered as if nothing had shifted, desyncing the
-// cursor. Fixed in #1315 by re-anchoring the viewport to the tail of the
-// collapsed content (repaintViewport).
-
-describe("e2e case01: collapse must keep the input box on screen", () => {
-	it("shows the content tail and input box after a 60 -> 8 line collapse", async () => {
-		const h = await createHarness([...Array.from({ length: 59 }, (_, i) => `old-${i}`), "[INPUT-BOX]"], {
-			rows: 10,
-		});
-
-		// Collapse far above the viewport top (anchor is at 50) with a
-		// changed line above it — the original failure combination.
-		await h.frame(["new-0", "new-1", "new-2", "new-3", "new-4", "new-5", "new-6", "[INPUT-BOX]"]);
-
-		const viewport = h.terminal.getViewport();
-		assert.ok(
-			viewport.some((line) => line.includes("[INPUT-BOX]")),
-			`input box must stay visible, got: ${JSON.stringify(viewport)}`,
-		);
-		assert.ok(
-			viewport.some((line) => line.includes("new-0")),
-			"collapsed content must be visible",
-		);
-
-		// Self-healing: the next differential frame must land in place.
-		await h.frame(["new-0", "new-1", "new-2", "new-3", "new-4", "new-5", "new-6", "[INPUT-BOX]x"]);
-		assert.ok(
-			h.terminal.getViewport().some((line) => line.includes("[INPUT-BOX]x")),
-			"frame after the collapse must update the input box in place",
-		);
-
-		h.stop();
-	});
-
-	it("re-anchors to the tail when collapsed content is still taller than the screen", async () => {
-		const h = await createHarness([...Array.from({ length: 99 }, (_, i) => `old-${i}`), "[INPUT-BOX]"], {
-			rows: 10,
-		});
-
-		await h.frame([...Array.from({ length: 29 }, (_, i) => `new-${i}`), "[INPUT-BOX]"]);
-
-		const viewport = h.terminal.getViewport();
-		assert.ok(viewport[9]!.includes("[INPUT-BOX]"), `input box must sit on the bottom row, got: ${JSON.stringify(viewport)}`);
-		assert.ok(viewport[0]!.includes("new-20"), "viewport must show the tail of the new content");
-
-		h.stop();
-	});
-});
diff --git a/packages/pi-tui/e2e/case02-collapse-scroll-position.test.ts b/packages/pi-tui/e2e/case02-collapse-scroll-position.test.ts
deleted file mode 100644
index e403818e2..000000000
--- a/packages/pi-tui/e2e/case02-collapse-scroll-position.test.ts
+++ /dev/null
@@ -1,53 +0,0 @@
-import assert from "node:assert";
-import { describe, it } from "node:test";
-import { createHarness, type WriteCapturingTerminal } from "./harness.ts";
-
-// Case 02 — scroll position yanked while reading scrollback.
-//
-// Symptom: on Windows Terminal, when the transcript collapsed while the
-// user was scrolled up reading history, the view jumped to the absolute
-// top of scrollback (microsoft/Terminal#20370: ESC[3J while scrolled
-// into scrollback).
-//
-// Root cause: the fallback was a destructive full redraw that cleared
-// scrollback with ESC[3J. Fixed in #1315: the collapse repaints only the
-// live screen area, never emits ESC[3J, and leaves the scroll position
-// alone.
-
-describe("e2e case02: collapse must not yank the user's scroll position", () => {
-	it("preserves scroll position and never emits ESC[3J during a collapse", async () => {
-		const h = await createHarness([...Array.from({ length: 59 }, (_, i) => `old-${i}`), "[INPUT-BOX]"], {
-			rows: 10,
-			capture: true,
-		});
-		const terminal = h.terminal as WriteCapturingTerminal;
-
-		// User scrolls up into scrollback and starts reading.
-		terminal.scrollViewport(-20);
-		const scrolledPosition = terminal.getScrollPosition();
-		assert.ok(terminal.getViewport().some((line) => line.includes("old-35")));
-
-		terminal.writes = [];
-		await h.frame(["new-0", "new-1", "new-2", "new-3", "new-4", "new-5", "new-6", "[INPUT-BOX]"]);
-
-		assert.strictEqual(terminal.getScrollPosition(), scrolledPosition, "scroll position must be preserved");
-		assert.ok(
-			terminal.getViewport().some((line) => line.includes("old-35")),
-			"the user's scrolled view must still show the history",
-		);
-		assert.ok(
-			!terminal.writes.join("").includes("\x1b[3J"),
-			"a collapse must never clear scrollback with ESC[3J",
-		);
-
-		// Scrolling back down reveals the fresh content.
-		terminal.scrollToBottom();
-		const viewport = terminal.getViewport();
-		assert.ok(
-			viewport.some((line) => line.includes("[INPUT-BOX]")),
-			`input box must be at the bottom after scrolling down, got: ${JSON.stringify(viewport)}`,
-		);
-
-		h.stop();
-	});
-});
diff --git a/packages/pi-tui/e2e/case03-full-redraw-residue.test.ts b/packages/pi-tui/e2e/case03-full-redraw-residue.test.ts
deleted file mode 100644
index 004933b01..000000000
--- a/packages/pi-tui/e2e/case03-full-redraw-residue.test.ts
+++ /dev/null
@@ -1,70 +0,0 @@
-import assert from "node:assert";
-import { describe, it } from "node:test";
-import { countInBuffer, createHarness } from "./harness.ts";
-
-// Case 03 — stale text above the welcome banner; duplicated rows after
-// expansion toggles.
-//
-// Symptom (a): after /new, /clear, or a session switch, the new session's
-// welcome banner rendered with the previous session's text still visible
-// above it.
-// Symptom (b): pressing ctrl+o to expand collapsed tool output rendered a
-// duplicated copy of earlier content above the transcript.
-//
-// Root cause: both flows replace the content wholesale, which the
-// differential renderer cannot reconcile against an unrelated previous
-// frame. Fixed in #1315 at the app layer: kimi-code calls
-// `requestRender(true)` on session reset and on expansion toggles. This
-// case guards the TUI primitive those fixes rely on: a forced render
-// repaints the screen from scratch, leaving no residue and no duplicates
-// in the visible viewport.
-
-describe("e2e case03: forced full redraw leaves no residue on screen", () => {
-	it("clears previous-session text from the screen on a forced render (/clear)", async () => {
-		const h = await createHarness([...Array.from({ length: 59 }, (_, i) => `old-${i}`), "[INPUT-BOX]"], {
-			rows: 10,
-		});
-
-		// Session switch: unrelated short content + forced full redraw.
-		await h.frame(["[WELCOME]", "", "[INPUT-BOX]"], true);
-
-		const viewport = h.terminal.getViewport();
-		assert.ok(viewport.some((line) => line.includes("[WELCOME]")), "welcome banner must be visible");
-		assert.ok(viewport.some((line) => line.includes("[INPUT-BOX]")), "input box must be visible");
-		assert.ok(
-			!viewport.some((line) => line.includes("old-")),
-			`no previous-session text may remain on screen, got: ${JSON.stringify(viewport)}`,
-		);
-
-		h.stop();
-	});
-
-	it("renders expanded content exactly once on a forced render (ctrl+o)", async () => {
-		const collapsed = [
-			...Array.from({ length: 40 }, (_, i) => `line-${i}`),
-			"... (100 more lines, ctrl+o to expand)",
-			"[INPUT-BOX]",
-		];
-		const h = await createHarness(collapsed, { rows: 10 });
-
-		// Expansion regrows the transcript wholesale + forced full redraw.
-		const expanded = [
-			...Array.from({ length: 40 }, (_, i) => `line-${i}`),
-			...Array.from({ length: 20 }, (_, i) => `detail-${i}`),
-			"[INPUT-BOX]",
-		];
-		await h.frame(expanded, true);
-
-		const viewport = h.terminal.getViewport();
-		assert.ok(viewport[9]!.includes("[INPUT-BOX]"), "input box must sit on the bottom row");
-		for (const marker of ["detail-12", "detail-19"]) {
-			assert.strictEqual(
-				countInBuffer(viewport, marker),
-				1,
-				`"${marker}" must appear exactly once in the viewport`,
-			);
-		}
-
-		h.stop();
-	});
-});
diff --git a/packages/pi-tui/e2e/case04-oscillation-duplication.test.ts b/packages/pi-tui/e2e/case04-oscillation-duplication.test.ts
deleted file mode 100644
index 8931242f4..000000000
--- a/packages/pi-tui/e2e/case04-oscillation-duplication.test.ts
+++ /dev/null
@@ -1,62 +0,0 @@
-import assert from "node:assert";
-import { describe, it } from "node:test";
-import { assertExactlyOnce, createHarness } from "./harness.ts";
-
-// Case 04 — transcript spans duplicated in scrollback during streaming.
-//
-// Symptom: while an agent streamed output, scrolling up showed the same
-// span of transcript (activity lines, messages) repeated over and over;
-// each shrink/grow oscillation of the live region stacked another copy.
-//
-// Root cause: a partial shrink re-anchored (rewound) previousViewportTop,
-// repainting rows scrollback already held; the next growth scrolled them
-// out again. Fixed in #1353: the anchor never rewinds on a partial shrink
-// (it stays pinned; growth refills the gap), so every row is committed to
-// scrollback exactly once.
-
-describe("e2e case04: shrink/grow oscillation must not duplicate scrollback", () => {
-	const transcript = (status: string, activity: string[]): string[] => [
-		...Array.from({ length: 30 }, (_, i) => `msg-${i}`),
-		status,
-		...Array.from({ length: 25 }, (_, i) => `out-${i}`),
-		...activity,
-		"[INPUT-BOX]",
-	];
-	const fullActivity = ["act-0", "act-1", "act-2", "act-3"];
-
-	it("keeps every row exactly once across repeated oscillations", async () => {
-		const h = await createHarness(transcript("status-0", fullActivity), { rows: 10 });
-
-		// Three oscillations: the activity pane collapses and regrows while
-		// a status line above the viewport keeps changing (streaming reflow).
-		for (let cycle = 1; cycle <= 3; cycle++) {
-			await h.frame(transcript(`status-${cycle}a`, []));
-			await h.frame(transcript(`status-${cycle}b`, fullActivity));
-		}
-
-		// Stable rows must appear exactly once — no duplicated spans, no
-		// losses. (Status lines are excluded: they legitimately leave stale
-		// copies above the viewport.)
-		assertExactlyOnce(h.terminal, ["msg-29", "out-0", "out-13", "out-24", "act-0", "act-3", "[INPUT-BOX]"]);
-
-		const viewport = h.terminal.getViewport();
-		assert.ok(viewport[9]!.includes("[INPUT-BOX]"), "input box must be back on the bottom row");
-
-		h.stop();
-	});
-
-	it("keeps the pinned gap bounded and refills it on growth", async () => {
-		const h = await createHarness(transcript("status-0", fullActivity), { rows: 10 });
-
-		await h.frame(transcript("status-0", []));
-		const pinned = h.terminal.getViewport();
-		const inputRow = pinned.findIndex((line) => line.includes("[INPUT-BOX]"));
-		assert.ok(inputRow >= 0 && inputRow < 9, "input box hovers above a bounded blank gap while pinned");
-		assert.strictEqual(pinned[9], "", "rows below the pinned content stay blank");
-
-		await h.frame(transcript("status-0", fullActivity));
-		assert.ok(h.terminal.getViewport()[9]!.includes("[INPUT-BOX]"), "growth refills the gap to the bottom row");
-
-		h.stop();
-	});
-});
diff --git a/packages/pi-tui/e2e/case05-growth-past-anchor-row-loss.test.ts b/packages/pi-tui/e2e/case05-growth-past-anchor-row-loss.test.ts
deleted file mode 100644
index 3890305f3..000000000
--- a/packages/pi-tui/e2e/case05-growth-past-anchor-row-loss.test.ts
+++ /dev/null
@@ -1,54 +0,0 @@
-import assert from "node:assert";
-import { describe, it } from "node:test";
-import { createHarness } from "./harness.ts";
-
-// Case 05 — transcript rows missing from scrollback after streaming.
-//
-// Symptom: after long streaming turns, scrolling up showed gaps: spans of
-// transcript rows were simply absent from scrollback.
-//
-// Root cause (invariant 2, exactly-once commit): when a single frame both
-// changed a line above the viewport (status/reflow) and grew the content
-// past the pinned anchor, the length-change branch advanced the anchor and
-// repainted the screen in place without scrolling. The rows between the
-// old and new anchor were overwritten on screen and never committed to
-// scrollback. Found by review on #1353.
-//
-// Fixed on #1353: an anchor advance now paints from the old anchor and
-// scrolls the skipped rows into scrollback, committing each exactly once.
-
-describe("e2e case05: growth past the anchor must not lose rows", () => {
-	it("commits the rows skipped by an anchor advance exactly once", async () => {
-		// 60 lines at height 10 -> anchor 50; rows 50..59 are on screen and
-		// not yet committed to scrollback.
-		const h = await createHarness([...Array.from({ length: 59 }, (_, i) => `row-${i}`), "[INPUT-BOX]"], {
-			rows: 10,
-		});
-
-		// One frame combines an above-viewport change (row-10 completes)
-		// with growth past the anchor (3 appended rows): anchor 50 -> 53.
-		const grown = [
-			...Array.from({ length: 59 }, (_, i) => (i === 10 ? "row-10 [done]" : `row-${i}`)),
-			"tail-0",
-			"tail-1",
-			"tail-2",
-			"[INPUT-BOX]",
-		];
-		await h.frame(grown);
-
-		// The rows the anchor skipped over must be in the buffer exactly
-		// once — they crossed the viewport top and have to be committed.
-		const buffer = h.terminal.getScrollBuffer();
-		for (const marker of ["row-50", "row-51", "row-52"]) {
-			const count = buffer.filter((line) => line.includes(marker)).length;
-			assert.strictEqual(count, 1, `"${marker}" must survive the anchor advance, got ${count} occurrences`);
-		}
-
-		// And the fresh tail is visible with the input box at the bottom.
-		const viewport = h.terminal.getViewport();
-		assert.ok(viewport.some((line) => line.includes("tail-2")), "appended rows must be visible");
-		assert.ok(viewport[9]!.includes("[INPUT-BOX]"), "input box must sit on the bottom row");
-
-		h.stop();
-	});
-});
diff --git a/packages/pi-tui/e2e/case06-cursor-above-pinned-window.test.ts b/packages/pi-tui/e2e/case06-cursor-above-pinned-window.test.ts
deleted file mode 100644
index d154bcea4..000000000
--- a/packages/pi-tui/e2e/case06-cursor-above-pinned-window.test.ts
+++ /dev/null
@@ -1,57 +0,0 @@
-import assert from "node:assert";
-import { describe, it } from "node:test";
-import { CURSOR_MARKER } from "../src/tui.ts";
-import { countInBuffer, createHarness } from "./harness.ts";
-
-// Case 06 — rows written to the wrong screen position after a pinned shrink.
-//
-// Symptom: after the transcript shrank while the viewport stayed pinned,
-// subsequent updates landed on the wrong screen rows: lines duplicated or
-// misplaced a couple of rows below where they belonged.
-//
-// Root cause (invariant 3, cursor bookkeeping sync): extractCursorPosition
-// scans the bottom `height` rows of the content, but a pinned repaint
-// paints `pinnedTop..pinnedTop+height-1` — a higher window. A cursor
-// marker in the gap between the two (e.g. a tall input editor poking above
-// the pinned window) made positionHardwareCursor record hardwareCursorRow
-// on an invisible logical row while the real cursor clamped at the screen
-// top. The next differential frame computed its relative move from the
-// desynced value and wrote to the wrong rows. Found by review on #1353.
-//
-// Fixed on #1353: the cursor is only positioned when the marker row is
-// inside the visible window; otherwise it is hidden and the bookkeeping
-// stays on the real cursor row.
-
-describe("e2e case06: pinned repaint must keep cursor bookkeeping in sync", () => {
-	it("places the next differential update on the correct screen row", async () => {
-		// 60 lines at height 10 -> anchor 50; cursor marker at the bottom.
-		const h = await createHarness(
-			[...Array.from({ length: 59 }, (_, i) => `old-${i}`), `[INPUT]${CURSOR_MARKER}`],
-			{ rows: 10 },
-		);
-
-		// Shrink 60 -> 56 with everything shifted (change above the
-		// viewport): the viewport stays pinned at 50, painting rows 50..55.
-		// The cursor marker sits at row 48 — inside the bottom-10 scan
-		// window (46..55) but above the painted window.
-		const pinned = Array.from({ length: 56 }, (_, i) => (i === 48 ? `new-48${CURSOR_MARKER}` : `new-${i}`));
-		await h.frame(pinned);
-
-		// Next frame changes row 55 (screen row 5 of the pinned window).
-		const next = pinned.map((line, i) => (i === 55 ? "new-55 CHANGED" : line));
-		await h.frame(next);
-
-		const viewport = h.terminal.getViewport();
-		assert.ok(
-			viewport[5]!.includes("new-55 CHANGED"),
-			`row 55 must render on screen row 5, got: ${JSON.stringify(viewport)}`,
-		);
-		assert.strictEqual(
-			countInBuffer(viewport, "new-55"),
-			1,
-			"the changed row must not be duplicated onto another screen row",
-		);
-
-		h.stop();
-	});
-});
diff --git a/packages/pi-tui/e2e/harness.ts b/packages/pi-tui/e2e/harness.ts
deleted file mode 100644
index ca9f349a5..000000000
--- a/packages/pi-tui/e2e/harness.ts
+++ /dev/null
@@ -1,86 +0,0 @@
-import assert from "node:assert";
-import { type Component, TUI } from "../src/tui.ts";
-import { VirtualTerminal } from "../test/virtual-terminal.ts";
-
-/** A component whose rendered lines are fully controlled by the test. */
-export class Lines implements Component {
-	private lines: string[] = [];
-
-	setLines(lines: string[]): void {
-		this.lines = lines;
-	}
-
-	render(): string[] {
-		return this.lines;
-	}
-
-	invalidate(): void {}
-}
-
-/** VirtualTerminal that also records every raw write for escape-sequence assertions. */
-export class WriteCapturingTerminal extends VirtualTerminal {
-	writes: string[] = [];
-
-	override write(data: string): void {
-		this.writes.push(data);
-		super.write(data);
-	}
-}
-
-export interface Harness<T extends VirtualTerminal = VirtualTerminal> {
-	terminal: T;
-	tui: TUI;
-	content: Lines;
-	/** Replace the content lines and wait for the next render to settle. */
-	frame(lines: string[], force?: boolean): Promise<void>;
-	stop(): void;
-}
-
-/** Build a TUI driven by a single Lines component on a virtual terminal. */
-export async function createHarness(
-	initialLines: string[],
-	options?: { columns?: number; rows?: number; capture?: boolean },
-): Promise<Harness<VirtualTerminal | WriteCapturingTerminal>> {
-	const columns = options?.columns ?? 60;
-	const rows = options?.rows ?? 10;
-	const terminal = options?.capture ? new WriteCapturingTerminal(columns, rows) : new VirtualTerminal(columns, rows);
-	const tui = new TUI(terminal);
-	const content = new Lines();
-	tui.addChild(content);
-	content.setLines(initialLines);
-	tui.start();
-	await terminal.waitForRender();
-	return {
-		terminal,
-		tui,
-		content,
-		async frame(lines: string[], force = false): Promise<void> {
-			content.setLines(lines);
-			tui.requestRender(force);
-			await terminal.waitForRender();
-		},
-		stop(): void {
-			tui.stop();
-		},
-	};
-}
-
-/** Count buffer lines (scrollback + screen) containing the marker. */
-export function countInBuffer(buffer: string[], marker: string): number {
-	return buffer.filter((line) => line.includes(marker)).length;
-}
-
-/**
- * Assert each marker appears exactly once across scrollback + screen.
- * Catches both duplication (count > 1) and row loss (count === 0).
- * Only use markers whose logical line did not change between frames:
- * lines rewritten above the viewport legitimately leave a stale copy
- * in scrollback (see e2e/README.md, "stale bytes" trade-off).
- */
-export function assertExactlyOnce(terminal: VirtualTerminal, markers: string[]): void {
-	const buffer = terminal.getScrollBuffer();
-	for (const marker of markers) {
-		const count = countInBuffer(buffer, marker);
-		assert.strictEqual(count, 1, `"${marker}" should appear exactly once in the buffer, got ${count}`);
-	}
-}
diff --git a/packages/pi-tui/package.json b/packages/pi-tui/package.json
index 7071d677d..9c961cc24 100644
--- a/packages/pi-tui/package.json
+++ b/packages/pi-tui/package.json
@@ -56,8 +56,7 @@
 	"scripts": {
 		"build": "tsdown",
 		"typecheck": "tsc -p tsconfig.json --noEmit",
-		"test": "node --test test/*.test.ts e2e/*.test.ts",
-		"test:e2e": "node --test e2e/*.test.ts",
+		"test": "node --test test/*.test.ts",
 		"clean": "rm -rf dist"
 	},
 	"dependencies": {
diff --git a/packages/pi-tui/src/tui.ts b/packages/pi-tui/src/tui.ts
index 8d6f168df..c578c7d93 100644
--- a/packages/pi-tui/src/tui.ts
+++ b/packages/pi-tui/src/tui.ts
@@ -1341,7 +1341,7 @@ export class TUI extends Container {
 			}
 			const bufferLength = Math.max(height, newLines.length);
 			this.previousViewportTop = Math.max(0, bufferLength - height);
-			this.positionHardwareCursor(cursorPos, newLines.length, this.previousViewportTop, height);
+			this.positionHardwareCursor(cursorPos, newLines.length);
 			this.previousLines = newLines;
 			this.previousKittyImageIds = this.collectKittyImageIds(newLines);
 			this.previousWidth = width;
@@ -1388,104 +1388,6 @@ export class TUI extends Container {
 			return;
 		}
 
-		// Repaint the visible viewport in place with the tail of the new
-		// content, re-anchoring previousViewportTop to desiredTop. Used when
-		// the differential path cannot run safely or would push duplicate
-		// rows into scrollback. Emits no ESC[3J. When desiredTop advances
-		// past the current anchor, the skipped rows are painted with fresh
-		// content and scrolled into scrollback (committed exactly once);
-		// otherwise nothing scrolls, so scrollback and the user's scroll
-		// position stay intact.
-		const repaintViewport = (desiredTop: number, reason: string): void => {
-			// An advancing anchor must commit the rows it skips: paint from
-			// the old anchor and let the paint loop scroll `advance` rows out
-			// of the screen top. A pinned or rewound anchor paints the target
-			// window in place without scrolling.
-			const advance = Math.max(0, desiredTop - prevViewportTop);
-			const paintStart = advance > 0 ? prevViewportTop : desiredTop;
-			const paintCount = height + advance;
-			// Kitty image lines need multi-row placement; fall back to a
-			// destructive full render for that rare combination.
-			for (let r = 0; r < paintCount; r++) {
-				const idx = paintStart + r;
-				if (idx < newLines.length && isImageLine(newLines[idx]!)) {
-					logRedraw(`viewport repaint hit kitty image at line ${idx}`);
-					fullRender(true);
-					return;
-				}
-			}
-			logRedraw(`viewport repaint: ${reason}`);
-			let repaint = "\x1b[?2026h"; // Begin synchronized output
-			// Delete kitty images placed in the old visible viewport; images
-			// above it live in scrollback and are left alone. A multi-row
-			// image can straddle the viewport top: its id lives on the image
-			// line above prevViewportTop while its reserved rows are still
-			// visible, so widen the range to include such blocks — otherwise
-			// the stale overlay would survive the repaint and its id would
-			// drop out of previousKittyImageIds, never to be cleaned up.
-			let deleteFrom = prevViewportTop;
-			for (let k = 0; k < prevViewportTop; k++) {
-				const prevLine = this.previousLines[k] ?? "";
-				if (!isImageLine(prevLine)) continue;
-				const blockEnd = k + this.getKittyImageReservedRows(this.previousLines, k) - 1;
-				if (blockEnd >= prevViewportTop) {
-					deleteFrom = k;
-					break;
-				}
-			}
-			repaint += this.deleteChangedKittyImages(deleteFrom, this.previousLines.length - 1);
-			// Move the cursor to the top of the screen (old anchor still valid).
-			const cursorScreenRow = Math.max(0, Math.min(height - 1, hardwareCursorRow - prevViewportTop));
-			if (cursorScreenRow > 0) {
-				repaint += `\x1b[${cursorScreenRow}A`;
-			}
-			repaint += "\r";
-			// Rewrite paintCount rows from paintStart. Rows written past the
-			// bottom screen row scroll the terminal: with an advancing anchor
-			// the first `advance` rows (freshly painted) scroll into
-			// scrollback, committing them exactly once. With advance = 0 the
-			// last row gets no trailing \r\n, so nothing scrolls.
-			for (let r = 0; r < paintCount; r++) {
-				if (r > 0) repaint += "\r\n";
-				repaint += "\x1b[2K";
-				const idx = paintStart + r;
-				if (idx < newLines.length) {
-					repaint += newLines[idx]!;
-				}
-			}
-			repaint += "\x1b[?2026l"; // End synchronized output
-			this.terminal.write(repaint);
-			// Re-anchor: screen row r now shows newLines[desiredTop + r].
-			this.cursorRow = Math.max(0, newLines.length - 1);
-			this.hardwareCursorRow = desiredTop + height - 1;
-			this.previousViewportTop = desiredTop;
-			this.maxLinesRendered = Math.max(this.maxLinesRendered, newLines.length);
-			this.positionHardwareCursor(cursorPos, newLines.length, desiredTop, height);
-			this.previousLines = newLines;
-			this.previousKittyImageIds = this.collectKittyImageIds(newLines);
-			this.previousWidth = width;
-			this.previousHeight = height;
-		};
-
-		// Rewinding the viewport anchor below the scrollback high-water mark
-		// (previousViewportTop) repaints rows that scrollback already holds,
-		// and the next scroll commits them again — every rewind duplicates
-		// its span. So a shrink normally keeps the anchor pinned: the content
-		// bottom hovers above the screen bottom with a bounded blank gap that
-		// the next growth naturally fills. The single exception is a collapse
-		// — the content ends at or above the screen top (compaction, clears),
-		// where nothing sensible could be shown otherwise. There the rewind
-		// is unavoidable, and the content has changed so drastically that the
-		// duplicated span is not recognizable as such.
-		const desiredViewportTop = Math.max(0, newLines.length - height);
-		if (prevViewportTop > desiredViewportTop && newLines.length <= prevViewportTop) {
-			repaintViewport(
-				desiredViewportTop,
-				`re-anchor after collapse (viewportTop ${prevViewportTop} -> ${desiredViewportTop}, newLines=${newLines.length})`,
-			);
-			return;
-		}
-
 		// Find first and last changed lines
 		let firstChanged = -1;
 		let lastChanged = -1;
@@ -1517,7 +1419,7 @@ export class TUI extends Container {
 
 		// No changes - but still need to update hardware cursor position if it moved
 		if (firstChanged === -1) {
-			this.positionHardwareCursor(cursorPos, newLines.length, prevViewportTop, height);
+			this.positionHardwareCursor(cursorPos, newLines.length);
 			this.previousViewportTop = prevViewportTop;
 			this.previousHeight = height;
 			return;
@@ -1563,7 +1465,7 @@ export class TUI extends Container {
 				this.cursorRow = targetRow;
 				this.hardwareCursorRow = targetRow;
 			}
-			this.positionHardwareCursor(cursorPos, newLines.length, prevViewportTop, height);
+			this.positionHardwareCursor(cursorPos, newLines.length);
 			this.previousLines = newLines;
 			this.previousKittyImageIds = this.collectKittyImageIds(newLines);
 			this.previousWidth = width;
@@ -1573,63 +1475,11 @@ export class TUI extends Container {
 		}
 
 		// Differential rendering can only touch what was actually visible.
-		// If the first changed line is above the viewport, a destructive full
-		// redraw would clear scrollback and yank the user's viewport (on Windows
-		// Terminal, ESC[3J while scrolled into scrollback jumps to the absolute
-		// top — microsoft/Terminal#20370). Clamp the diff to the visible viewport
-		// and skip above-viewport changes: scrollback keeps stale bytes, but the
-		// user's scroll position is preserved.
+		// If the first changed line is above the previous viewport, we need a full redraw.
 		if (firstChanged < prevViewportTop) {
-			let visibleFirstChanged = -1;
-			for (let i = prevViewportTop; i <= lastChanged; i++) {
-				const oldLine = i < this.previousLines.length ? this.previousLines[i] : "";
-				const newLine = i < newLines.length ? newLines[i] : "";
-				if (oldLine !== newLine) {
-					visibleFirstChanged = i;
-					break;
-				}
-			}
-			if (visibleFirstChanged === -1) {
-				logRedraw(`all changes above viewport (firstChanged=${firstChanged} < ${prevViewportTop})`);
-				this.positionHardwareCursor(cursorPos, newLines.length, prevViewportTop, height);
-				this.previousLines = newLines;
-				this.previousKittyImageIds = this.collectKittyImageIds(newLines);
-				this.previousWidth = width;
-				this.previousHeight = height;
-				this.previousViewportTop = prevViewportTop;
-				return;
-			}
-			// The remaining visible changes are entirely in the deleted tail
-			// region. Reachable while a shrink is pinned: repaint the window
-			// at the pinned anchor, which clears the deleted rows without
-			// scrolling or rewinding.
-			if (visibleFirstChanged >= newLines.length) {
-				repaintViewport(
-					prevViewportTop,
-					`deleted tail within pinned viewport (newLines=${newLines.length}, viewportTop=${prevViewportTop})`,
-				);
-				return;
-			}
-			// A length change above the viewport shifts every line below it.
-			// Painting the shifted lines through the screen would push rows
-			// that are already in scrollback out again, stacking a duplicate
-			// copy there on every shrink/grow cycle (e.g. streaming content
-			// oscillating). Repaint the visible viewport instead: scrollback
-			// keeps the stale old version and the screen shows the fresh
-			// tail. The anchor never rewinds here (that would duplicate as
-			// well): it stays pinned on a shrink, and advances only when the
-			// content has outgrown the pinned window — repaintViewport then
-			// scrolls the skipped rows into scrollback so none are lost.
-			if (newLines.length !== this.previousLines.length) {
-				const repaintTop = Math.max(desiredViewportTop, prevViewportTop);
-				repaintViewport(
-					repaintTop,
-					`re-anchor after above-viewport length change (${this.previousLines.length} -> ${newLines.length}, viewportTop ${prevViewportTop} -> ${repaintTop})`,
-				);
-				return;
-			}
-			logRedraw(`clamped firstChanged ${firstChanged} -> ${visibleFirstChanged} (viewportTop=${prevViewportTop})`);
-			firstChanged = visibleFirstChanged;
+			logRedraw(`firstChanged < viewportTop (${firstChanged} < ${prevViewportTop})`);
+			fullRender(true);
+			return;
 		}
 
 		// Render from first changed line to end
@@ -1705,20 +1555,12 @@ export class TUI extends Container {
 				buffer += `\x1b[${moveDown}B`;
 				finalCursorRow = newLines.length - 1;
 			}
-			// Only clear what is actually on screen: writing \r\n past the
-			// bottom row would scroll the terminal without updating
-			// viewportTop/hardwareCursorRow, desyncing every later render.
-			// Rows below the screen bottom are invisible and need no clearing.
 			const extraLines = this.previousLines.length - newLines.length;
-			const rowsBelowCursor = height - 1 - (finalCursorRow - viewportTop);
-			const clearLines = Math.max(0, Math.min(extraLines, rowsBelowCursor));
-			for (let i = 0; i < clearLines; i++) {
+			for (let i = newLines.length; i < this.previousLines.length; i++) {
 				buffer += "\r\n\x1b[2K";
 			}
 			// Move cursor back to end of new content
-			if (clearLines > 0) {
-				buffer += `\x1b[${clearLines}A`;
-			}
+			buffer += `\x1b[${extraLines}A`;
 		}
 
 		buffer += "\x1b[?2026l"; // End synchronized output
@@ -1765,7 +1607,7 @@ export class TUI extends Container {
 		this.previousViewportTop = Math.max(prevViewportTop, finalCursorRow - height + 1);
 
 		// Position hardware cursor for IME
-		this.positionHardwareCursor(cursorPos, newLines.length, this.previousViewportTop, height);
+		this.positionHardwareCursor(cursorPos, newLines.length);
 
 		this.previousLines = newLines;
 		this.previousKittyImageIds = this.collectKittyImageIds(newLines);
@@ -1777,15 +1619,8 @@ export class TUI extends Container {
 	 * Position the hardware cursor for IME candidate window.
 	 * @param cursorPos The cursor position extracted from rendered output, or null
 	 * @param totalLines Total number of rendered lines
-	 * @param viewportTop Logical row shown on the top screen row after this frame
-	 * @param height Terminal height (visible viewport size)
 	 */
-	private positionHardwareCursor(
-		cursorPos: { row: number; col: number } | null,
-		totalLines: number,
-		viewportTop: number,
-		height: number,
-	): void {
+	private positionHardwareCursor(cursorPos: { row: number; col: number } | null, totalLines: number): void {
 		if (!cursorPos || totalLines <= 0) {
 			this.terminal.hideCursor();
 			return;
@@ -1795,17 +1630,6 @@ export class TUI extends Container {
 		const targetRow = Math.max(0, Math.min(cursorPos.row, totalLines - 1));
 		const targetCol = Math.max(0, cursorPos.col);
 
-		// The hardware cursor can only sit inside the visible window. A
-		// marker outside it (e.g. a tall editor poking above a pinned
-		// viewport) must not move the cursor: the ANSI moves would clamp at
-		// the screen edge while hardwareCursorRow recorded the unreachable
-		// row, desyncing every later differential move. Hide the cursor and
-		// keep the bookkeeping on the real cursor row instead.
-		if (targetRow < viewportTop || targetRow >= viewportTop + height) {
-			this.terminal.hideCursor();
-			return;
-		}
-
 		// Move cursor from current position to target
 		const rowDelta = targetRow - this.hardwareCursorRow;
 		let buffer = "";
diff --git a/packages/pi-tui/test/tui-render.test.ts b/packages/pi-tui/test/tui-render.test.ts
index d33bca4d8..f928f7015 100644
--- a/packages/pi-tui/test/tui-render.test.ts
+++ b/packages/pi-tui/test/tui-render.test.ts
@@ -658,7 +658,7 @@ describe("TUI differential rendering", () => {
 		tui.stop();
 	});
 
-	it("re-anchors without a full redraw when deleted lines move the viewport upward", async () => {
+	it("full re-renders when deleted lines move the viewport upward", async () => {
 		const terminal = new VirtualTerminal(20, 5);
 		const tui = new TUI(terminal);
 		const component = new TestComponent();
@@ -674,7 +674,7 @@ describe("TUI differential rendering", () => {
 		tui.requestRender();
 		await terminal.waitForRender();
 
-		assert.strictEqual(tui.fullRedraws, initialRedraws, "Shrink should re-anchor in place, not full-redraw");
+		assert.ok(tui.fullRedraws > initialRedraws, "Shrink should trigger a full redraw");
 		assert.deepStrictEqual(terminal.getViewport(), ["Line 2", "Line 3", "Line 4", "Line 5", "Line 6"]);
 
 		tui.stop();
@@ -696,8 +696,7 @@ describe("TUI differential rendering", () => {
 		tui.requestRender();
 		await terminal.waitForRender();
 
-		assert.strictEqual(tui.fullRedraws, initialRedraws, "Shrink should re-anchor in place, not full-redraw");
-		assert.deepStrictEqual(terminal.getViewport(), ["Line 0", "Line 1", "", "", ""]);
+		assert.ok(tui.fullRedraws > initialRedraws, "Shrink should reset the viewport with a full redraw");
 		const redrawsAfterShrink = tui.fullRedraws;
 
 		component.lines = ["Line 0", "Line 1", "Line 2"];
@@ -741,10 +740,12 @@ describe("TUI differential rendering", () => {
 		tui.requestRender();
 		await terminal.waitForRender();
 
-		assert.strictEqual(
-			tui.fullRedraws,
-			redrawsBeforeSwitch,
-			"Branch switch should not trigger a full redraw (repainted in place)",
+		// Upstream behavior: a change above the viewport triggers a
+		// destructive full redraw, which repaints the tail of the new
+		// content and leaves no stale rows on screen.
+		assert.ok(
+			tui.fullRedraws > redrawsBeforeSwitch,
+			"Branch switch above the viewport should trigger a full redraw",
 		);
 
 		const viewport = terminal.getViewport();
@@ -755,55 +756,25 @@ describe("TUI differential rendering", () => {
 			assert.ok(!line.includes("Chat 14"), `Stale "Chat 14" at viewport row ${i}`);
 		}
 
-		// Partial shrinks keep the viewport anchor pinned (rewinding would
-		// duplicate scrollback rows), so the remaining content sits at the
-		// top of the window with blank rows below. The stale "Chat 12/13/14"
-		// rows remain in scrollback but are not visible.
+		// The full redraw shows the tail of the new content with the editor
+		// at the bottom.
 		assert.deepStrictEqual(viewport, [
+			"Chat 5",
+			"Chat 6",
+			"Chat 7",
+			"Chat 8",
+			"Chat 9",
+			"Chat 10",
+			"Chat 11",
+			"Editor 0",
 			"Editor 1",
 			"Editor 2",
-			"",
-			"",
-			"",
-			"",
-			"",
-			"",
-			"",
-			"",
 		]);
 
 		tui.stop();
 	});
 });
 
-
-describe("TUI scrollback preservation", () => {
-	it("does not emit full redraw when changes are above the viewport", async () => {
-		const terminal = new LoggingVirtualTerminal(40, 5);
-		const tui = new TUI(terminal);
-		const component = new TestComponent();
-		tui.addChild(component);
-
-		// Render 8 lines into a height-5 terminal so previousViewportTop > 0
-		// (viewport shows lines 3..7, lines 0..2 are above the viewport).
-		component.lines = ["line0", "line1", "line2", "line3", "line4", "line5", "line6", "line7"];
-		tui.start();
-		await terminal.waitForRender();
-		terminal.clearWrites();
-
-		// Change a line above the viewport (line0); this must not trigger fullRender.
-		component.lines[0] = "line0-changed";
-		tui.requestRender();
-		await terminal.waitForRender();
-
-		const writes = terminal.getWrites();
-		assert.ok(!writes.includes("\x1b[3J"), "should not clear scrollback (no ESC[3J)");
-		assert.ok(!writes.includes("\x1b[2J"), "should not full redraw (no ESC[2J)");
-
-		tui.stop();
-	});
-});
-
 describe("Container width clamping", () => {
 	it("clamps non-positive widths to 1 before rendering children", () => {
 		const container = new Container();
diff --git a/packages/pi-tui/test/tui-shrink.test.ts b/packages/pi-tui/test/tui-shrink.test.ts
deleted file mode 100644
index c5992b9b4..000000000
--- a/packages/pi-tui/test/tui-shrink.test.ts
+++ /dev/null
@@ -1,330 +0,0 @@
-import assert from "node:assert";
-import { describe, it } from "node:test";
-import { type Component, TUI } from "../src/tui.ts";
-import { VirtualTerminal } from "./virtual-terminal.ts";
-
-class Lines implements Component {
-	private lines: string[];
-
-	constructor(lines: string[]) {
-		this.lines = lines;
-	}
-
-	setLines(lines: string[]): void {
-		this.lines = lines;
-	}
-
-	render(): string[] {
-		return this.lines;
-	}
-
-	invalidate(): void {}
-}
-
-class WriteCapturingTerminal extends VirtualTerminal {
-	writes: string[] = [];
-
-	override write(data: string): void {
-		this.writes.push(data);
-		super.write(data);
-	}
-}
-
-describe("TUI shrinking content", () => {
-	it("clears all rendered lines when content shrinks to zero", async () => {
-		const terminal = new VirtualTerminal(40, 10);
-		const tui = new TUI(terminal);
-		const content = new Lines(["first", "second", "third"]);
-		tui.addChild(content);
-		tui.start();
-		await terminal.waitForRender();
-
-		assert.ok(terminal.getViewport().some((line) => line.includes("first")));
-		assert.ok(terminal.getViewport().some((line) => line.includes("second")));
-		assert.ok(terminal.getViewport().some((line) => line.includes("third")));
-
-		tui.clear();
-		tui.requestRender();
-		await terminal.waitForRender();
-
-		const viewport = terminal.getViewport();
-		assert.ok(!viewport.some((line) => line.includes("first")), "first line should be cleared");
-		assert.ok(!viewport.some((line) => line.includes("second")), "second line should be cleared");
-		assert.ok(!viewport.some((line) => line.includes("third")), "third line should be cleared");
-
-		tui.stop();
-	});
-
-	it("repaints the viewport when content collapses above it with an above-viewport change", async () => {
-		// Regression: compaction/collapse shrinks 30 lines to 8 (below the
-		// viewport top at 20) while a line above the viewport also changes.
-		// The clamped differential path used to desync the cursor and leave
-		// the viewport blank with the input box gone.
-		const terminal = new VirtualTerminal(40, 10);
-		const tui = new TUI(terminal);
-		const content = new Lines([]);
-		tui.addChild(content);
-
-		content.setLines([...Array.from({ length: 29 }, (_, i) => `L${i}`), "[INPUT-BOX]"]);
-		tui.start();
-		await terminal.waitForRender();
-		assert.ok(terminal.getViewport().some((line) => line.includes("[INPUT-BOX]")));
-
-		content.setLines(["L0", "L1", "L2", "L3", "L4", "L5-CHANGED", "L6", "[INPUT-BOX]"]);
-		tui.requestRender();
-		await terminal.waitForRender();
-
-		const viewport = terminal.getViewport();
-		assert.ok(
-			viewport.some((line) => line.includes("[INPUT-BOX]")),
-			`input box should stay visible, got: ${JSON.stringify(viewport)}`,
-		);
-		assert.ok(viewport.some((line) => line.includes("L5-CHANGED")));
-
-		// Scrollback must be preserved (no ESC[3J): old history stays above.
-		assert.ok(
-			terminal.getScrollBuffer().some((line) => line.includes("L15")),
-			"scrollback should keep the old history",
-		);
-
-		// Subsequent renders must land in the right place (self-healing).
-		content.setLines(["L0", "L1", "L2", "L3", "L4", "L5-CHANGED", "L6", "[INPUT-BOX]x"]);
-		tui.requestRender();
-		await terminal.waitForRender();
-		assert.ok(
-			terminal.getViewport().some((line) => line.includes("[INPUT-BOX]x")),
-			"render after the collapse should update the input box in place",
-		);
-
-		tui.stop();
-	});
-
-	it("preserves the user's scroll position when content collapses while scrolled up", async () => {
-		// While the user is reading scrollback, the collapse repaint must only
-		// touch the live screen area at the bottom of the buffer: no ESC[3J,
-		// no viewport yank. Scrolling back down shows the fresh content.
-		const terminal = new VirtualTerminal(40, 10);
-		const tui = new TUI(terminal);
-		const content = new Lines([]);
-		tui.addChild(content);
-
-		content.setLines([...Array.from({ length: 29 }, (_, i) => `L${i}`), "[INPUT-BOX]"]);
-		tui.start();
-		await terminal.waitForRender();
-
-		// User scrolls up into scrollback.
-		terminal.scrollViewport(-10);
-		const scrolledPosition = terminal.getScrollPosition();
-		assert.ok(scrolledPosition < 20, "user should be scrolled into scrollback");
-		assert.ok(terminal.getViewport().some((line) => line.includes("L10")));
-
-		content.setLines(["L0", "L1", "L2", "L3", "L4", "L5-CHANGED", "L6", "[INPUT-BOX]"]);
-		tui.requestRender();
-		await terminal.waitForRender();
-
-		// The user's scrolled view must not move, and still shows the history.
-		assert.strictEqual(terminal.getScrollPosition(), scrolledPosition, "scroll position should be preserved");
-		assert.ok(terminal.getViewport().some((line) => line.includes("L10")));
-
-		// Scrolling back down reveals the repainted content with the input box.
-		terminal.scrollToBottom();
-		const viewport = terminal.getViewport();
-		assert.ok(
-			viewport.some((line) => line.includes("[INPUT-BOX]")),
-			`input box should be visible at the bottom, got: ${JSON.stringify(viewport)}`,
-		);
-		assert.ok(viewport.some((line) => line.includes("L5-CHANGED")));
-
-		tui.stop();
-	});
-
-	it("deletes a kitty image straddling the viewport top when content collapses", async () => {
-		// A multi-row image can start above the viewport top while its
-		// reserved rows are still visible. The collapse repaint must widen
-		// its image-delete range to that block, or the stale overlay
-		// survives and its id drops out of tracking.
-		const terminal = new WriteCapturingTerminal(40, 10);
-		const tui = new TUI(terminal);
-		const content = new Lines([]);
-		tui.addChild(content);
-
-		// 30 lines, image line at index 18 with 4 reserved rows (18..21),
-		// straddling the viewport top at 20.
-		const imageLine = "\x1b_Ga=T,i=42,r=4;AAAA\x1b\\";
-		const first = [
-			...Array.from({ length: 18 }, (_, i) => `L${i}`),
-			imageLine,
-			"",
-			"",
-			"",
-			...Array.from({ length: 7 }, (_, i) => `L${22 + i}`),
-			"[INPUT-BOX]",
-		];
-		content.setLines(first);
-		tui.start();
-		await terminal.waitForRender();
-
-		terminal.writes = [];
-		content.setLines(["L0", "L1", "L2", "L3", "L4", "L5-CHANGED", "L6", "[INPUT-BOX]"]);
-		tui.requestRender();
-		await terminal.waitForRender();
-
-		const written = terminal.writes.join("");
-		assert.ok(
-			written.includes("\x1b_Ga=d,d=I,i=42,q=2\x1b\\"),
-			"the straddling image should be deleted during the collapse repaint",
-		);
-		assert.ok(terminal.getViewport().some((line) => line.includes("[INPUT-BOX]")));
-
-		tui.stop();
-	});
-
-	it("re-anchors the input box to the screen bottom when content collapses past the viewport top", async () => {
-		// Regression: previousViewportTop only ever grows; when content
-		// collapses to or above the viewport top (compaction, clears) the
-		// viewport must rewind so the tail of the new content is shown.
-		const terminal = new VirtualTerminal(40, 10);
-		const tui = new TUI(terminal);
-		const content = new Lines([]);
-		tui.addChild(content);
-
-		content.setLines([...Array.from({ length: 59 }, (_, i) => `old-${i}`), "[INPUT-BOX]"]);
-		tui.start();
-		await terminal.waitForRender();
-		assert.ok(terminal.getViewport()[9]!.includes("[INPUT-BOX]"));
-
-		// Collapse 60 -> 30 lines (30 <= viewportTop 50); content is still
-		// taller than the screen, so the tail must land at the screen bottom.
-		content.setLines([...Array.from({ length: 29 }, (_, i) => `new-${i}`), "[INPUT-BOX]"]);
-		tui.requestRender();
-		await terminal.waitForRender();
-
-		const viewport = terminal.getViewport();
-		assert.ok(
-			viewport[9]!.includes("[INPUT-BOX]"),
-			`input box should sit on the bottom screen row, got: ${JSON.stringify(viewport)}`,
-		);
-		assert.ok(viewport[0]!.includes("new-20"), "viewport should show the tail of the new content");
-
-		// Subsequent renders must land in the right place (self-healing).
-		content.setLines([...Array.from({ length: 29 }, (_, i) => `new-${i}`), "[INPUT-BOX]x"]);
-		tui.requestRender();
-		await terminal.waitForRender();
-		assert.ok(terminal.getViewport()[9]!.includes("[INPUT-BOX]x"));
-
-		tui.stop();
-	});
-
-	it("does not duplicate scrollback rows on a shrink/grow cycle with above-viewport changes", async () => {
-		// Regression: a shrink re-anchor rewinds viewportTop; if the next
-		// grow with an above-viewport change painted from the rewound top
-		// through the end, rows already in scrollback were pushed out again,
-		// stacking a duplicate copy there on every oscillation.
-		const terminal = new VirtualTerminal(60, 10);
-		const tui = new TUI(terminal);
-		const content = new Lines([]);
-		tui.addChild(content);
-
-		const base = (status: string, tail: string[]): string[] => [
-			...Array.from({ length: 5 }, (_, i) => `L${i}`),
-			status,
-			...Array.from({ length: 48 }, (_, i) => `M${i}`),
-			...tail,
-			"[INPUT]",
-		];
-
-		content.setLines(base("status-A", ["** marker message **"]));
-		tui.start();
-		await terminal.waitForRender();
-
-		// Shrink by a few rows (activity pane collapsing) -> re-anchor.
-		content.setLines(base("status-A", ["** marker message **"]).slice(0, -4).concat(["[INPUT]"]));
-		tui.requestRender();
-		await terminal.waitForRender();
-
-		// Grow back with an above-viewport change (reflow/status update).
-		content.setLines(base("status-B", ["** marker message **"]));
-		tui.requestRender();
-		await terminal.waitForRender();
-
-		const buffer = terminal.getScrollBuffer();
-		for (const marker of ["M37", "M39", "** marker message **"]) {
-			const count = buffer.filter((line) => line.includes(marker)).length;
-			assert.strictEqual(count, 1, `"${marker}" should appear exactly once, got ${count}`);
-		}
-		const viewport = terminal.getViewport();
-		assert.ok(viewport[9]!.includes("[INPUT]"), "input box should sit on the bottom screen row");
-		assert.ok(viewport.some((line) => line.includes("** marker message **")));
-
-		tui.stop();
-	});
-
-	it("keeps the viewport pinned on partial shrinks and lets growth refill the gap", async () => {
-		// Rewinding the anchor would repaint rows scrollback already holds
-		// and duplicate them on the next scroll, so a partial shrink stays
-		// pinned: the input box hovers above a bounded blank gap that the
-		// next growth naturally fills. No rewind, no duplication.
-		const terminal = new VirtualTerminal(40, 10);
-		const tui = new TUI(terminal);
-		const content = new Lines([]);
-		tui.addChild(content);
-
-		content.setLines([...Array.from({ length: 59 }, (_, i) => `old-${i}`), "[INPUT-BOX]"]);
-		tui.start();
-		await terminal.waitForRender();
-		assert.ok(terminal.getViewport()[9]!.includes("[INPUT-BOX]"));
-
-		// Shrink by 4 rows; content still spans the pinned viewport (56 > 50).
-		content.setLines([...Array.from({ length: 55 }, (_, i) => `old-${i}`), "[INPUT-BOX]"]);
-		tui.requestRender();
-		await terminal.waitForRender();
-
-		// The viewport stays pinned: the input box hovers above blank rows.
-		const pinned = terminal.getViewport();
-		assert.ok(pinned[5]!.includes("[INPUT-BOX]"), `expected pinned gap, got: ${JSON.stringify(pinned)}`);
-		assert.strictEqual(pinned[9], "", "rows below the content should be blank while pinned");
-
-		// Growth fills the gap; the input box returns to the bottom row and
-		// nothing was duplicated in the buffer along the way.
-		content.setLines([...Array.from({ length: 59 }, (_, i) => `old-${i}`), "[INPUT-BOX]"]);
-		tui.requestRender();
-		await terminal.waitForRender();
-		const grown = terminal.getViewport();
-		assert.ok(grown[9]!.includes("[INPUT-BOX]"), `input box should be back at the bottom, got: ${JSON.stringify(grown)}`);
-		const buffer = terminal.getScrollBuffer();
-		for (const marker of ["old-40", "old-54", "[INPUT-BOX]"]) {
-			const count = buffer.filter((line) => line.includes(marker)).length;
-			assert.strictEqual(count, 1, `"${marker}" should appear exactly once, got ${count}`);
-		}
-
-		tui.stop();
-	});
-
-	it("shows the tail of collapsed content when it is still taller than the screen", async () => {
-		// 100 lines -> 30 lines (still > height 10) with a change above the
-		// viewport: the viewport should show the tail of the new content.
-		const terminal = new VirtualTerminal(40, 10);
-		const tui = new TUI(terminal);
-		const content = new Lines([]);
-		tui.addChild(content);
-
-		content.setLines(Array.from({ length: 100 }, (_, i) => `old-${i}`));
-		tui.start();
-		await terminal.waitForRender();
-
-		const newLines = Array.from({ length: 30 }, (_, i) => `new-${i}`);
-		content.setLines(newLines);
-		tui.requestRender();
-		await terminal.waitForRender();
-
-		const viewport = terminal.getViewport();
-		for (let i = 20; i < 30; i++) {
-			assert.ok(
-				viewport.some((line) => line.includes(`new-${i}`)),
-				`tail line new-${i} should be visible, got: ${JSON.stringify(viewport)}`,
-			);
-		}
-
-		tui.stop();
-	});
-});
diff --git a/packages/pi-tui/test/virtual-terminal.ts b/packages/pi-tui/test/virtual-terminal.ts
index 067c8b7b4..4e067f4e5 100644
--- a/packages/pi-tui/test/virtual-terminal.ts
+++ b/packages/pi-tui/test/virtual-terminal.ts
@@ -135,27 +135,6 @@ export class VirtualTerminal implements Terminal {
 		});
 	}
 
-	/**
-	 * Simulate the user scrolling the terminal window (negative = up into scrollback).
-	 */
-	scrollViewport(lines: number): void {
-		this.xterm.scrollLines(lines);
-	}
-
-	/**
-	 * Current scroll position of the user-visible window (buffer.viewportY).
-	 */
-	getScrollPosition(): number {
-		return this.xterm.buffer.active.viewportY;
-	}
-
-	/**
-	 * Scroll the user-visible window back to the bottom of the buffer.
-	 */
-	scrollToBottom(): void {
-		this.xterm.scrollToBottom();
-	}
-
 	/**
 	 * Flush and get viewport - convenience method for tests
 	 */