fix(tui): stopped direct herdr pane flicker

Kept direct Herdr panes on the host-safe in-place resize path so streaming redraws no longer clear and replay pane scrollback.

Updated the resize regression, stress scenario, renderer docs, and changelog.

Fixes #8431

docs/tui-core-renderer.md

@@ -66,7 +66,7 @@ needs to know whether the user has scrolled away from the tail.
 - A component tree that reports **no seam** gets shell semantics: whatever
   scrolls off is final. Shrinking such a frame into its committed prefix
   re-anchors the window and leaves the stale copy in history (§3).
-- Inside ED3-unsafe multiplexers, a width change terminates the physical-row
+- Inside terminal multiplexers, a width change terminates the physical-row
   coordinate epoch. The renderer captures an opaque
   `NativeScrollbackWidthEpoch` marker from the last emitted source state before
   `SIGWINCH`, then resolves that same logical boundary after the settled-width
@@ -77,11 +77,9 @@ needs to know whether the user has scrolled away from the tail.
   and no old viewport row is recommitted. Components without the source
   contract retain the conservative physical-row fallback. Visible overlays
   freeze the seam and pinned live regions clip advancement at their final
-  boundary. Height-only resizes retain the existing ledger.
-- Direct HerdR panes are not in that category. HerdR's Ghostty core implements
-  ED3, so OMP clears and replays its source-owned transcript after settlement,
-  matching direct terminals. Repainting host-reflowed rows in place would
-  harden soft wraps and leave residual rows after a later width reversal.
+  boundary. Height-only resizes retain the existing ledger. Direct HerdR panes
+  use this path because clearing and replaying scrollback flickers in its
+  host-owned pane.
 
 ---
 
@@ -188,20 +186,19 @@ contract, not a terminal-specific optimization.
    deliberate exception: it clears and replays the complete current frame.
 3. **Commits are exactly the chunk.** Any byte shape that scrolls the screen
    must scroll only rows accounted for by the commit advance.
-4. **An ED3-unsafe multiplexer width resize NEVER advances history.** The old
-   committed physical-row coordinate is opaque after reflow. The resize leaves
-   the host-reflowed viewport in place and establishes a complete-frame
-   baseline independent of the native commit count. Subsequent growth writes
-   the exact current-width rows newly crossing the seam—not blank scroll
-   commands—then repaints the bounded viewport; only that slice advances
-   commits. Visible overlays advance neither the baseline nor the seam ledger;
-   overlay exit backfills the exact hidden slice. Pinned live regions advance
-   only through their final boundary; finalization releases the deferred
-   mutable slice. During a height shrink, only occupied old-frame rows actually
-   moved into history by the host are excluded from the append-owned seam;
-   empty viewport rows do not consume content-driven movement. Height-only
-   resizes do not terminate the epoch. Direct HerdR uses ED3 source replay
-   instead.
+4. **A multiplexer width resize NEVER advances history.** The old committed
+   physical-row coordinate is opaque after reflow. The resize leaves the
+   host-reflowed viewport in place and establishes a complete-frame baseline
+   independent of the native commit count. Subsequent growth writes the exact
+   current-width rows newly crossing the seam—not blank scroll commands—then
+   repaints the bounded viewport; only that slice advances commits. Visible
+   overlays advance neither the baseline nor the seam ledger; overlay exit
+   backfills the exact hidden slice. Pinned live regions advance only through
+   their final boundary; finalization releases the deferred mutable slice.
+   During a height shrink, only occupied old-frame rows actually moved into
+   history by the host are excluded from the append-owned seam; empty viewport
+   rows do not consume content-driven movement. Height-only resizes do not
+   terminate the epoch.
 5. **NEVER probe the viewport position or fork on platform in the update
    path.** win32 behaves like POSIX. The probe APIs are gone; do not
    reintroduce them.

docs/tui-runtime-internals.md

@@ -162,9 +162,10 @@ Resize events are event-driven from `ProcessTerminal` to `TUI.requestRender()`.
 
 Effects:
 
-- A resize is an explicit user gesture: on direct terminals and direct HerdR panes the engine erases and replays (`ED3` + full paint) so history rewraps at the new geometry; the commit ledger restarts from the replayed frame. HerdR's Ghostty core supports ED3, and replay avoids converting its reflowed soft wraps into permanent row boundaries.
-- Inside ED3-unsafe terminal multiplexers, height-only resize retains the append ledger and repaints the visible window in place after the settle debounce (issue #2088). A width change instead terminates the physical-row epoch: old committed coordinates become opaque, pane history remains immutable at its authored wrap, and the settled render leaves the host-reflowed viewport in place. The current frame length becomes a baseline independent of the native committed-row count. Subsequent growth writes the exact current-width rows newly crossing the scrollback seam, follows them with a bounded viewport repaint, and advances commits by exactly that emitted slice. Ordinary and forced renders arriving during the debounce are folded into the settled repaint without postponing source updates.
-- Nested tmux, screen, Zellij, or cmux sessions inside HerdR remain on the ED3-unsafe path because the inner multiplexer owns its history.
+- Direct HerdR panes follow the in-place multiplexer path: their host owns the
+  pane, and destructive `ED3` transcript replay produces visible flashes.
+- Inside terminal multiplexers, height-only resize retains the append ledger and repaints the visible window in place after the settle debounce (issue #2088). A width change instead terminates the physical-row epoch: old committed coordinates become opaque, pane history remains immutable at its authored wrap, and the settled render establishes a complete-frame baseline. Subsequent growth writes only current-width rows newly crossing the scrollback seam before repainting the bounded viewport.
+- Nested tmux, screen, Zellij, or cmux sessions inside HerdR use the same path.
 - Terminals that re-report their size when the alternate screen buffer is toggled (Warp reports a height one row different for the alt buffer) take the in-place path too. The non-multiplexer fast path borrows the alternate screen for drag frames, so on these terminals each alt enter/leave emits a fresh resize event, which re-enters the fast path — a self-sustaining loop that floods ED3 full repaints with stable geometry. `resizeRepaintsInPlace()` (covering ED3-unsafe multiplexers and these terminals; overridable via `PI_TUI_RESIZE_IN_PLACE`) routes them through the in-place repaint, which never touches the alt buffer.
 - Overlay visibility can depend on terminal dimensions (`OverlayOptions.visible`); focus is corrected when overlays become non-visible after resize.
 

packages/tui/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed direct Herdr panes continuously flashing during transcript streaming by keeping resize redraws on the pane-safe in-place path instead of clearing and replaying host-owned scrollback ([#8431](https://github.com/can1357/oh-my-pi/issues/8431)).
+
 ## [17.3.0] - 2026-08-13
 
 ### Fixed
@@ -251,7 +255,7 @@
 
 ### Changed
 
- - Improved native scrollback history management by introducing an optional erase-and-replay mechanism to rebuild scrollback when mutated rows (such as finalized tool blocks or collapsed transcripts) diverge. This is now gated behind the `tui.scrollbackRebuild` setting and defaults to off.
+- Improved native scrollback history management by introducing an optional erase-and-replay mechanism to rebuild scrollback when mutated rows (such as finalized tool blocks or collapsed transcripts) diverge. This is now gated behind the `tui.scrollbackRebuild` setting and defaults to off.
 
 ### Fixed
 
@@ -600,7 +604,7 @@
 - Added `ctrl+j` as a second default binding for the `tui.input.newLine` action alongside `shift+enter`, so terminals that cannot emit `shift+enter` still have a newline key. On terminals with Kitty-protocol / `modifyOtherKeys` disambiguation `ctrl+j` inserts a newline while `Enter` still submits; on legacy terminals where `ctrl+j` and `Enter` are both byte-identical `LF` it submits (documented limitation). User keybinding overrides still take precedence ([#2473](https://github.com/can1357/oh-my-pi/issues/2473))
 - Added an `Editor.onLargePaste(text, lineCount)` hook, fired for a "marker-sized" paste (the point where the editor would otherwise collapse it into a `[Paste #N]` token). Returning `true` lets the host intercept the paste — e.g. to offer wrap-in-code-block / wrap-in-XML / attach-as-file choices — and suppresses the default marker (no undo state is recorded). Added `Editor.insertPaste(content)` so the host can re-insert a (possibly transformed) collapsed paste marker without re-triggering the hook.
 - Added `Editor.deleteBeforeCursor(count)`, which removes up to `count` characters immediately before the cursor on the current line (capped at the cursor column, single line, records one undo state). Hosts use it to "track back" optimistically-inserted characters — e.g. the coding-agent hold-`Space` push-to-talk gesture deleting the space-bar auto-repeat burst.
-- Added an optional `getNativeScrollbackSnapshotSafeEnd()` to the `NativeScrollbackLiveRegion` contract: a *durable* commit boundary (D ≥ the byte-stable `commitSafeEnd`) for live rows whose current snapshot is permanent content but may still drift bytes later (a streaming markdown table re-aligning its columns). The engine commits these rows when they scroll above the window — never dropping them — but **audit-exempt** (tracked via a new byte-stable `auditRows` prefix), so a later layout change of an already-committed row freezes a stale row in history (duplication never loss) instead of re-anchoring the committed-prefix audit and spraying duplicate snapshots. Components that omit it are unchanged: `durableBoundary === byteStableBoundary` and `auditRows === committedRows`, so the ledger math is byte-identical.
+- Added an optional `getNativeScrollbackSnapshotSafeEnd()` to the `NativeScrollbackLiveRegion` contract: a _durable_ commit boundary (D ≥ the byte-stable `commitSafeEnd`) for live rows whose current snapshot is permanent content but may still drift bytes later (a streaming markdown table re-aligning its columns). The engine commits these rows when they scroll above the window — never dropping them — but **audit-exempt** (tracked via a new byte-stable `auditRows` prefix), so a later layout change of an already-committed row freezes a stale row in history (duplication never loss) instead of re-anchoring the committed-prefix audit and spraying duplicate snapshots. Components that omit it are unchanged: `durableBoundary === byteStableBoundary` and `auditRows === committedRows`, so the ledger math is byte-identical.
 
 ### Fixed
 
@@ -841,7 +845,7 @@
 
 ### Fixed
 
-- Fixed Windows ConPTY session-resume painting the transcript with the last several rows truncated below the viewport until Alt+Tab forced a host repaint. After `sessionReplace`/`historyRebuild`/`overlayRebuild` paints that scroll-push content into native scrollback, the renderer now arms a 150 ms ConPTY settle window that coalesces spinner/blink-driven `requestRender(false)` calls into a single trailing render — Windows Terminal's viewport-follow logic no longer falls further behind the cursor on every tick of the post-paint storm. The arm also reclaims any render request queued *during* the in-flight composition (notably `ImageBudget.endPass()` calling `requestRender()` synchronously when a frame trips the live-graphics cap): without that, the queued request sat on the standard 30 Hz throttle and fired at ~33 ms — well inside the 150 ms quiet window — defeating the coalescing. Bumped the ConPTY per-`WriteFile` chunk cap from 8 KiB to 16 KiB so a multi-megabyte resume paint emits half as many writes (still well under the ~32 KiB threshold from #2034 that the original cap defends against), and made the cap measure encoded UTF-8 bytes instead of JS code units so a CJK-heavy transcript can't silently inflate a 16-KiB-of-code-units chunk into ~48 KiB of `WriteFile` traffic and reintroduce the #2034 viewport bug ([#2095](https://github.com/can1357/oh-my-pi/issues/2095)).
+- Fixed Windows ConPTY session-resume painting the transcript with the last several rows truncated below the viewport until Alt+Tab forced a host repaint. After `sessionReplace`/`historyRebuild`/`overlayRebuild` paints that scroll-push content into native scrollback, the renderer now arms a 150 ms ConPTY settle window that coalesces spinner/blink-driven `requestRender(false)` calls into a single trailing render — Windows Terminal's viewport-follow logic no longer falls further behind the cursor on every tick of the post-paint storm. The arm also reclaims any render request queued _during_ the in-flight composition (notably `ImageBudget.endPass()` calling `requestRender()` synchronously when a frame trips the live-graphics cap): without that, the queued request sat on the standard 30 Hz throttle and fired at ~33 ms — well inside the 150 ms quiet window — defeating the coalescing. Bumped the ConPTY per-`WriteFile` chunk cap from 8 KiB to 16 KiB so a multi-megabyte resume paint emits half as many writes (still well under the ~32 KiB threshold from #2034 that the original cap defends against), and made the cap measure encoded UTF-8 bytes instead of JS code units so a CJK-heavy transcript can't silently inflate a 16-KiB-of-code-units chunk into ~48 KiB of `WriteFile` traffic and reintroduce the #2034 viewport bug ([#2095](https://github.com/can1357/oh-my-pi/issues/2095)).
 
 ## [15.10.3] - 2026-06-08
 
@@ -1084,7 +1088,7 @@
 
 ### Fixed
 
-- Fixed native Windows + Windows Terminal freezing the editor on the wrap keystroke, on `/plan`/`/resume`/model-switch/status-line toggles, and on any other offscreen structural mutation until the next prompt submit. The `15.7.5` `#1635` fix routed every viewport-saturating pure-append and structural mutation through `deferredMutation` (a literal no-op) whenever `isNativeViewportAtBottom()` returned `undefined` — which it always does under `WT_SESSION` because the kernel32 probe can't see WT host scrollback. The deferral was only ever meant for the *confirmed-scrolled* case; an unknown viewport now falls back to a non-destructive `viewportRepaint` instead, so the live UI keeps updating without emitting `\x1b[3J` and without yanking a possibly-scrolled reader. Confirmed-scrolled frames (probe returns `false`) still defer.
+- Fixed native Windows + Windows Terminal freezing the editor on the wrap keystroke, on `/plan`/`/resume`/model-switch/status-line toggles, and on any other offscreen structural mutation until the next prompt submit. The `15.7.5` `#1635` fix routed every viewport-saturating pure-append and structural mutation through `deferredMutation` (a literal no-op) whenever `isNativeViewportAtBottom()` returned `undefined` — which it always does under `WT_SESSION` because the kernel32 probe can't see WT host scrollback. The deferral was only ever meant for the _confirmed-scrolled_ case; an unknown viewport now falls back to a non-destructive `viewportRepaint` instead, so the live UI keeps updating without emitting `\x1b[3J` and without yanking a possibly-scrolled reader. Confirmed-scrolled frames (probe returns `false`) still defer.
 - Removed the hard-coded 20-result cap on `@`-prefixed fuzzy file completion in `CombinedAutocompleteProvider.#getFuzzyFileSuggestions`. The dropdown now honors the existing `maxResults: 100` ceiling already configured for `fuzzyFind`, so projects with many files sharing a common stem (e.g. `@controller`, `@test`) surface all relevant matches instead of being silently truncated. ([#1652](https://github.com/can1357/oh-my-pi/issues/1652))
 
 ## [15.7.5] - 2026-06-01

packages/tui/src/tui.ts

@@ -413,27 +413,9 @@ function parseSizeValue(value: SizeValue | undefined, referenceSize: number): nu
 	return undefined;
 }
 
-/**
- * Detect sessions where ED3 cannot safely rebuild scrollback. A direct HerdR
- * pane is deliberately excluded: HerdR's Ghostty core implements ED3, so the
- * source-owned replay used by direct terminals is both supported and the only
- * way to avoid hardening host-reflowed soft wraps. Nested multiplexers remain
- * unsafe because the inner tmux/screen/Zellij layer still owns its history.
- */
+/** Detect terminal multiplexers where scrollback clearing and height-change redraws are hostile. */
 function isMultiplexerSession(): boolean {
-	if (!isInsideTerminalMultiplexer()) return false;
-	if (Bun.env.HERDR_ENV !== "1") return true;
-	const term = Bun.env.TERM?.toLowerCase() ?? "";
-	return Boolean(
-		Bun.env.TMUX ||
-			Bun.env.STY ||
-			Bun.env.ZELLIJ ||
-			Bun.env.CMUX_WORKSPACE_ID ||
-			Bun.env.CMUX_SURFACE_ID ||
-			Bun.env.CMUX_REMOTE_TRANSPORT ||
-			term.startsWith("tmux") ||
-			term.startsWith("screen"),
-	);
+	return isInsideTerminalMultiplexer();
 }
 
 /**
@@ -561,7 +543,11 @@ export class Container
 			component: Component;
 			childBoundary: unknown;
 			sourceIndex: number;
-			leading: ReadonlyArray<{ component: Component; revision: number | undefined; rowCount: number }>;
+			leading: ReadonlyArray<{
+				component: Component;
+				revision: number | undefined;
+				rowCount: number;
+			}>;
 			trailing: ReadonlyArray<{
 				component: Component;
 				revision: number | undefined;
@@ -1427,8 +1413,16 @@ export class TUI extends Container {
 			component: Component;
 			childBoundary: unknown;
 			sourceIndex: number;
-			leading: ReadonlyArray<{ component: Component; revision: number | undefined; rowCount: number }>;
-			trailing: ReadonlyArray<{ component: Component; revision: number | undefined; rowCount: number }>;
+			leading: ReadonlyArray<{
+				component: Component;
+				revision: number | undefined;
+				rowCount: number;
+			}>;
+			trailing: ReadonlyArray<{
+				component: Component;
+				revision: number | undefined;
+				rowCount: number;
+			}>;
 			hasTrailingRows: boolean;
 		}
 	>();
@@ -1932,7 +1926,12 @@ export class TUI extends Container {
 	 */
 	showOverlay(component: Component, options?: OverlayOptions): OverlayHandle {
 		component.setIgnoreTight?.(true);
-		const entry = { component, options, preFocus: this.#focusedComponent, hidden: false };
+		const entry = {
+			component,
+			options,
+			preFocus: this.#focusedComponent,
+			hidden: false,
+		};
 		this.overlayStack.push(entry);
 		// Only focus if overlay is actually visible
 		if (this.#isOverlayVisible(entry)) {
@@ -2122,7 +2121,9 @@ export class TUI extends Container {
 		this.#recordHardwareCursorHidden();
 		this.#querySixelSupport();
 		this.#queryCellSize();
-		this.requestRender(true, { clearScrollback: options?.clearScrollback === true });
+		this.requestRender(true, {
+			clearScrollback: options?.clearScrollback === true,
+		});
 	}
 
 	addStartListener(listener: StartListener): () => void {
@@ -2387,7 +2388,10 @@ export class TUI extends Container {
 		// the same `#prepareForcedRender(!isMultiplexerSession())` path via
 		// `requestRender(true)`, so the clear-scrollback intent is preserved.
 		if (this.#multiplexerResizeTimer) {
-			this.#armMultiplexerResizeTimer({ clearScrollback: !isMultiplexerSession(), hasPendingRender: true });
+			this.#armMultiplexerResizeTimer({
+				clearScrollback: !isMultiplexerSession(),
+				hasPendingRender: true,
+			});
 			return;
 		}
 		this.#prepareForcedRender(!isMultiplexerSession());
@@ -2997,7 +3001,12 @@ export class TUI extends Container {
 		// Parse margin (clamp to non-negative)
 		const margin =
 			typeof opt.margin === "number"
-				? { top: opt.margin, right: opt.margin, bottom: opt.margin, left: opt.margin }
+				? {
+						top: opt.margin,
+						right: opt.margin,
+						bottom: opt.margin,
+						left: opt.margin,
+					}
 				: (opt.margin ?? {});
 		const marginTop = Math.max(0, margin.top ?? 0);
 		const marginRight = Math.max(0, margin.right ?? 0);
@@ -3827,7 +3836,10 @@ export class TUI extends Container {
 			window = this.#compositeOverlaysIntoWindow(window, width, height);
 			const overlayMarkers = this.#extractCursorMarkers(window);
 			if (overlayMarkers.length > 0) {
-				cursorPos = { row: windowTop + overlayMarkers[0]!.row, col: overlayMarkers[0]!.col };
+				cursorPos = {
+					row: windowTop + overlayMarkers[0]!.row,
+					col: overlayMarkers[0]!.col,
+				};
 			}
 			window = this.#prepareLinesArray(window, width);
 		}
@@ -4419,7 +4431,10 @@ export class TUI extends Container {
 		this.#hardwareCursorVisible = false;
 		this.#hardwareCursorVisibilityKnown = true;
 		if (!this.#hardwareCursorState) return;
-		this.#hardwareCursorState = { ...this.#hardwareCursorState, visible: false };
+		this.#hardwareCursorState = {
+			...this.#hardwareCursorState,
+			visible: false,
+		};
 	}
 
 	#forgetHardwareCursorState(): void {
@@ -4594,7 +4609,10 @@ export class TUI extends Container {
 			if (cursorPos.row < chunkTo) {
 				paintCursorPos = cursorPos;
 			} else if (cursorPos.row >= windowTop && cursorPos.row < windowTop + height) {
-				paintCursorPos = { row: chunkTo + cursorPos.row - windowTop, col: cursorPos.col };
+				paintCursorPos = {
+					row: chunkTo + cursorPos.row - windowTop,
+					col: cursorPos.col,
+				};
 			}
 		}
 		// ConPTY hosts bound bulk transcript-replacement replays (resume, handoff,
@@ -4856,7 +4874,11 @@ export class TUI extends Container {
 		const framed: string[] = new Array(extra + height);
 		for (let k = 0; k < extra; k++) framed[k] = tail[tail.length - 1 - k]!;
 		for (let screenRow = 0; screenRow < height; screenRow++) framed[extra + screenRow] = window[screenRow]!;
-		return { framed: this.#prepareLinesArray(framed, width), viewportTop: extra, contentRows };
+		return {
+			framed: this.#prepareLinesArray(framed, width),
+			viewportTop: extra,
+			contentRows,
+		};
 	}
 
 	/**
@@ -5287,7 +5309,13 @@ export class TUI extends Container {
 		// No IME target or no content — hide cursor regardless of preference.
 		const target = this.#targetHardwareCursorState(cursorPos, totalLines);
 		if (!target) {
-			return { seq: "\x1b[?25l", toRow: fromRow, toCol: 0, visible: false, state: null };
+			return {
+				seq: "\x1b[?25l",
+				toRow: fromRow,
+				toCol: 0,
+				visible: false,
+				state: null,
+			};
 		}
 
 		// Move cursor from current position to target.
@@ -5302,7 +5330,13 @@ export class TUI extends Container {
 		seq += `\x1b[${target.col + 1}G`;
 		seq += target.visible ? "\x1b[?25h" : "\x1b[?25l";
 
-		return { seq, toRow: target.row, toCol: target.col, visible: target.visible, state: target };
+		return {
+			seq,
+			toRow: target.row,
+			toCol: target.col,
+			visible: target.visible,
+			state: target,
+		};
 	}
 
 	#isHiddenCursorKnown(): boolean {

packages/tui/test/issue-2088-repro.test.ts

@@ -414,7 +414,11 @@ class ManualRenderScheduler implements RenderScheduler {
 	}
 
 	scheduleRender(callback: () => void, delayMs: number): RenderTimer {
-		const timer = { at: this.#now + Math.max(0, delayMs), callback, canceled: false };
+		const timer = {
+			at: this.#now + Math.max(0, delayMs),
+			callback,
+			canceled: false,
+		};
 		this.#timers.push(timer);
 		return {
 			cancel: () => {
@@ -519,10 +523,27 @@ const MULTIPLEXER_ENV_KEYS = [
 const NO_MULTIPLEXER_ENV: Record<string, string | undefined> = Object.fromEntries(
 	MULTIPLEXER_ENV_KEYS.map(key => [key, undefined]),
 );
-const TMUX_ENV: Record<string, string | undefined> = { ...NO_MULTIPLEXER_ENV, TMUX: "1" };
+const TMUX_ENV: Record<string, string | undefined> = {
+	...NO_MULTIPLEXER_ENV,
+	TMUX: "1",
+};
 const MULTIPLEXER_ENV_CASES: Array<[string, Record<string, string | undefined>]> = [
-	["CMUX_WORKSPACE_ID", { ...NO_MULTIPLEXER_ENV, TERM: "dumb", CMUX_WORKSPACE_ID: "workspace:cmux-2088" }],
-	["CMUX_SURFACE_ID", { ...NO_MULTIPLEXER_ENV, TERM: "dumb", CMUX_SURFACE_ID: "surface:cmux-2088" }],
+	[
+		"CMUX_WORKSPACE_ID",
+		{
+			...NO_MULTIPLEXER_ENV,
+			TERM: "dumb",
+			CMUX_WORKSPACE_ID: "workspace:cmux-2088",
+		},
+	],
+	[
+		"CMUX_SURFACE_ID",
+		{
+			...NO_MULTIPLEXER_ENV,
+			TERM: "dumb",
+			CMUX_SURFACE_ID: "surface:cmux-2088",
+		},
+	],
 ];
 const CMUX_SOCKET_ONLY_ENV: Record<string, string | undefined> = {
 	...NO_MULTIPLEXER_ENV,
@@ -2512,7 +2533,7 @@ describe("multiplexer detection gates ED3 on resize", () => {
 		});
 	}
 
-	it("rebuilds direct HerdR scrollback from source across repeated widths", async () => {
+	it("repaints direct HerdR resizes in place without ED3", async () => {
 		await withEnvPatch({ ...NO_MULTIPLEXER_ENV, TERM: "dumb", HERDR_ENV: "1" }, async () => {
 			const term = new VirtualTerminal(40, 10, 1000);
 			const tui = new TUI(term);
@@ -2536,7 +2557,7 @@ describe("multiplexer detection gates ED3 on resize", () => {
 					}
 				}
 
-				expect(writes.join("")).toContain(ED3);
+				expect(writes.join("")).not.toContain(ED3);
 			} finally {
 				tui.stop();
 			}

packages/tui/test/render-stress-harness.ts

@@ -369,7 +369,11 @@ function contentOperation(
 	checksRowAccounting: boolean,
 	overrides: AppliedOperationOverrides = {},
 ): AppliedOperation {
-	return appliedOperation(kind, detail, { mutatesContent: true, checksRowAccounting, ...overrides });
+	return appliedOperation(kind, detail, {
+		mutatesContent: true,
+		checksRowAccounting,
+		...overrides,
+	});
 }
 
 function viewOperation(
@@ -414,18 +418,78 @@ interface BurstStepMetadata {
 }
 
 const BURST_STEP_METADATA = {
-	appendSmall: { mutatesContent: true, geometryChanged: false, forcedRender: false, mutatesViewport: false },
-	streamOne: { mutatesContent: true, geometryChanged: false, forcedRender: false, mutatesViewport: false },
-	appendRepeatedTail: { mutatesContent: true, geometryChanged: false, forcedRender: false, mutatesViewport: false },
-	injectBlankCluster: { mutatesContent: true, geometryChanged: false, forcedRender: false, mutatesViewport: false },
-	editVisibleLine: { mutatesContent: true, geometryChanged: false, forcedRender: false, mutatesViewport: false },
-	editOffscreenLine: { mutatesContent: true, geometryChanged: false, forcedRender: false, mutatesViewport: false },
-	tickStatusHeader: { mutatesContent: true, geometryChanged: false, forcedRender: false, mutatesViewport: false },
-	resizeWidth: { mutatesContent: false, geometryChanged: true, forcedRender: false, mutatesViewport: true },
-	resizeHeight: { mutatesContent: false, geometryChanged: true, forcedRender: false, mutatesViewport: true },
-	scrollPartial: { mutatesContent: false, geometryChanged: false, forcedRender: false, mutatesViewport: true },
-	scrollToBottom: { mutatesContent: false, geometryChanged: false, forcedRender: false, mutatesViewport: true },
-	forceRender: { mutatesContent: false, geometryChanged: false, forcedRender: true, mutatesViewport: true },
+	appendSmall: {
+		mutatesContent: true,
+		geometryChanged: false,
+		forcedRender: false,
+		mutatesViewport: false,
+	},
+	streamOne: {
+		mutatesContent: true,
+		geometryChanged: false,
+		forcedRender: false,
+		mutatesViewport: false,
+	},
+	appendRepeatedTail: {
+		mutatesContent: true,
+		geometryChanged: false,
+		forcedRender: false,
+		mutatesViewport: false,
+	},
+	injectBlankCluster: {
+		mutatesContent: true,
+		geometryChanged: false,
+		forcedRender: false,
+		mutatesViewport: false,
+	},
+	editVisibleLine: {
+		mutatesContent: true,
+		geometryChanged: false,
+		forcedRender: false,
+		mutatesViewport: false,
+	},
+	editOffscreenLine: {
+		mutatesContent: true,
+		geometryChanged: false,
+		forcedRender: false,
+		mutatesViewport: false,
+	},
+	tickStatusHeader: {
+		mutatesContent: true,
+		geometryChanged: false,
+		forcedRender: false,
+		mutatesViewport: false,
+	},
+	resizeWidth: {
+		mutatesContent: false,
+		geometryChanged: true,
+		forcedRender: false,
+		mutatesViewport: true,
+	},
+	resizeHeight: {
+		mutatesContent: false,
+		geometryChanged: true,
+		forcedRender: false,
+		mutatesViewport: true,
+	},
+	scrollPartial: {
+		mutatesContent: false,
+		geometryChanged: false,
+		forcedRender: false,
+		mutatesViewport: true,
+	},
+	scrollToBottom: {
+		mutatesContent: false,
+		geometryChanged: false,
+		forcedRender: false,
+		mutatesViewport: true,
+	},
+	forceRender: {
+		mutatesContent: false,
+		geometryChanged: false,
+		forcedRender: true,
+		mutatesViewport: true,
+	},
 } satisfies Record<BurstStepKind, BurstStepMetadata>;
 
 class UnknownViewportTerminal extends VirtualTerminal {
@@ -790,7 +854,11 @@ class StressModel {
 		const offscreenLimit = Math.max(1, this.lines.length - height - count);
 		const index = this.#rng.int(1, Math.max(1, offscreenLimit));
 		const removed = this.lines.splice(index, count);
-		return { index, count: removed.length, firstRemoved: removed[0]?.text ?? null };
+		return {
+			index,
+			count: removed.length,
+			firstRemoved: removed[0]?.text ?? null,
+		};
 	}
 
 	replaceAll(): JsonObject {
@@ -839,11 +907,17 @@ class StressModel {
 	rotateUp(): JsonObject {
 		if (this.lines.length < 2) {
 			this.lines.push(this.#freshLine("t"));
-			return { dropped: null, appended: this.lines[this.lines.length - 1]?.text ?? "" };
+			return {
+				dropped: null,
+				appended: this.lines[this.lines.length - 1]?.text ?? "",
+			};
 		}
 		const dropped = this.lines.shift();
 		this.lines.push(this.#randomLine("t"));
-		return { dropped: dropped?.text ?? null, appended: this.lines[this.lines.length - 1]?.text ?? "" };
+		return {
+			dropped: dropped?.text ?? null,
+			appended: this.lines[this.lines.length - 1]?.text ?? "",
+		};
 	}
 
 	collapseToFew(): JsonObject {
@@ -881,7 +955,13 @@ class StressModel {
 		const editedIndex = this.lines.length - 1;
 		const before = this.lines[editedIndex]?.text ?? "";
 		this.lines[editedIndex] = this.#freshLine("done");
-		return { start, count: removed.length, editedIndex, before, after: this.lines[editedIndex]?.text ?? "" };
+		return {
+			start,
+			count: removed.length,
+			editedIndex,
+			before,
+			after: this.lines[editedIndex]?.text ?? "",
+		};
 	}
 
 	swapOffscreenRows(height: number): JsonObject {
@@ -1046,7 +1126,12 @@ class StressOverlayModel {
 			const index = this.#rng.int(0, this.lines.length - 1);
 			const before = this.lines[index]?.text ?? "";
 			this.lines[index] = this.#freshLine("oe");
-			return { action: "edit", index, before, after: this.lines[index]?.text ?? "" };
+			return {
+				action: "edit",
+				index,
+				before,
+				after: this.lines[index]?.text ?? "",
+			};
 		}
 		if (action === 2) {
 			const index = this.#rng.int(0, this.lines.length - 1);
@@ -1183,7 +1268,12 @@ class StressDriver {
 				scenario.uniqueContent,
 				`child${id}-`,
 			);
-			return { id, model, component: new StressComponent(model, scenario.reflow), active: false };
+			return {
+				id,
+				model,
+				component: new StressComponent(model, scenario.reflow),
+				active: false,
+			};
 		});
 		this.#term = createTerminal(scenario);
 		// Capture every byte written to the terminal so per-op oracles can audit
@@ -1404,9 +1494,18 @@ class StressDriver {
 		const weighted: readonly WeightedCandidate<OperationKind>[] = [
 			{ item: "appendSmall", weight: 14 },
 			{ item: "streamOne", weight: 12 },
-			{ item: "appendExactWidth", weight: this.#scenario.uniqueContent ? 0 : 5 },
-			{ item: "appendRepeatedTail", weight: this.#scenario.uniqueContent ? 2 : 8 },
-			{ item: "appendDuplicateOfExisting", weight: this.#scenario.uniqueContent ? 2 : 8 },
+			{
+				item: "appendExactWidth",
+				weight: this.#scenario.uniqueContent ? 0 : 5,
+			},
+			{
+				item: "appendRepeatedTail",
+				weight: this.#scenario.uniqueContent ? 2 : 8,
+			},
+			{
+				item: "appendDuplicateOfExisting",
+				weight: this.#scenario.uniqueContent ? 2 : 8,
+			},
 			{ item: "injectBlankCluster", weight: 5 },
 			{ item: "appendBulk", weight: 3 },
 			{ item: "editVisibleLine", weight: 8 },
@@ -1433,7 +1532,10 @@ class StressDriver {
 			{ item: "moveCursorOffscreen", weight: 2 },
 			{ item: "showOverlay", weight: this.#overlays.length < 2 ? 3 : 1 },
 			{ item: "hideOverlay", weight: this.#overlays.length > 0 ? 2 : 0 },
-			{ item: "toggleOverlayHidden", weight: this.#overlays.length > 0 ? 2 : 0 },
+			{
+				item: "toggleOverlayHidden",
+				weight: this.#overlays.length > 0 ? 2 : 0,
+			},
 			{ item: "editOverlay", weight: this.#overlays.length > 0 ? 4 : 0 },
 			{ item: "moveOverlayCursor", weight: this.#overlays.length > 0 ? 2 : 0 },
 			{ item: "coalescedBurst", weight: 6 },
@@ -1451,10 +1553,22 @@ class StressDriver {
 			{ item: "resizeBoth", weight: 2 },
 			{ item: "resizeNoop", weight: 1 },
 			{ item: "resizeWithAppend", weight: 2 },
-			{ item: "attachChild", weight: this.#children.some(child => !child.active) ? 2 : 0 },
-			{ item: "detachChild", weight: this.#children.some(child => child.active) ? 2 : 0 },
-			{ item: "reorderChildren", weight: this.#children.filter(child => child.active).length > 1 ? 1 : 0 },
-			{ item: "mutateChild", weight: this.#children.some(child => child.active) ? 3 : 0 },
+			{
+				item: "attachChild",
+				weight: this.#children.some(child => !child.active) ? 2 : 0,
+			},
+			{
+				item: "detachChild",
+				weight: this.#children.some(child => child.active) ? 2 : 0,
+			},
+			{
+				item: "reorderChildren",
+				weight: this.#children.filter(child => child.active).length > 1 ? 1 : 0,
+			},
+			{
+				item: "mutateChild",
+				weight: this.#children.some(child => child.active) ? 3 : 0,
+			},
 		];
 		return weightedPick(this.#streams.ops, weighted);
 	}
@@ -1754,7 +1868,10 @@ class StressDriver {
 		this.#overlays = this.#overlays.filter(overlay => overlay !== entry);
 		this.#hiddenOverlaySentinels.add(entry.sentinel);
 		await this.#settle();
-		return this.#viewOperation("hideOverlay", { id: entry.id, sentinel: entry.sentinel });
+		return this.#viewOperation("hideOverlay", {
+			id: entry.id,
+			sentinel: entry.sentinel,
+		});
 	}
 
 	async #toggleOverlayHidden(): Promise<AppliedOperation> {
@@ -1874,7 +1991,10 @@ class StressDriver {
 	async #resizeNoop(): Promise<AppliedOperation> {
 		this.#term.resize(this.#term.columns, this.#term.rows);
 		await this.#settle();
-		return viewOperation("resizeNoop", { columns: this.#term.columns, rows: this.#term.rows });
+		return viewOperation("resizeNoop", {
+			columns: this.#term.columns,
+			rows: this.#term.rows,
+		});
 	}
 
 	async #scrollUp(): Promise<AppliedOperation> {
@@ -1886,7 +2006,9 @@ class StressDriver {
 
 	async #scrollToBottom(): Promise<AppliedOperation> {
 		this.#term.scrollLines(LARGE_SCROLL);
-		this.#tui.requestRender(true, { clearScrollback: this.#traits.strictNativeScrollback });
+		this.#tui.requestRender(true, {
+			clearScrollback: this.#traits.strictNativeScrollback,
+		});
 		await this.#settle();
 		return forceRenderOperation(
 			"scrollToBottom",
@@ -1957,7 +2079,12 @@ class StressDriver {
 		this.#term.scrollLines(LARGE_SCROLL);
 		this.#tui.requestRender(true, { clearScrollback: true });
 		await this.#settle();
-		return { ...this.#forceOperation("forceRenderClearScrollback", { clearScrollback: true }), checkpoint: true };
+		return {
+			...this.#forceOperation("forceRenderClearScrollback", {
+				clearScrollback: true,
+			}),
+			checkpoint: true,
+		};
 	}
 
 	async #forceRenderAfterEmptyOverflow(): Promise<AppliedOperation> {
@@ -1980,7 +2107,11 @@ class StressDriver {
 		this.#tui.requestRender(true);
 		await this.#settle();
 		return {
-			...this.#forceOperation("forceRenderAfterEmptyOverflow", { detachedChildren, empty, overflow }),
+			...this.#forceOperation("forceRenderAfterEmptyOverflow", {
+				detachedChildren,
+				empty,
+				overflow,
+			}),
 			mutatesContent: true,
 			// In multiplexers everything written during this op scrolls into pane
 			// history on top of whatever was already there.
@@ -2006,7 +2137,10 @@ class StressDriver {
 		}
 		this.#tui.requestRender();
 		await this.#settle();
-		return viewOperation("toggleFocusInput", { focused: this.#component.focused, cursor });
+		return viewOperation("toggleFocusInput", {
+			focused: this.#component.focused,
+			cursor,
+		});
 	}
 
 	// Container.addChild appends and Container.render walks children in array
@@ -2055,7 +2189,9 @@ class StressDriver {
 		await this.#settle();
 		return contentOperation(
 			"reorderChildren",
-			{ activeOrder: this.#children.filter(child => child.active).map(child => child.id) },
+			{
+				activeOrder: this.#children.filter(child => child.active).map(child => child.id),
+			},
 			false,
 		);
 	}
@@ -2412,7 +2548,9 @@ class StressDriver {
 	#assertCursor(op: AppliedOperation, before: Snapshot, after: Snapshot, index: number): void {
 		if (this.#hasVisibleOverlay()) return;
 		if (after.cursor.row < 0 || after.cursor.row >= after.height || after.cursor.col < 0) {
-			this.#fail("cursor bounds", op, before, after, index, { cursor: cursorObject(after) });
+			this.#fail("cursor bounds", op, before, after, index, {
+				cursor: cursorObject(after),
+			});
 		}
 		const expectedCursor = after.expectedCursor;
 		if (expectedCursor === null || !after.atBottom) return;
@@ -2762,7 +2900,9 @@ class StressDriver {
 		for (const sentinel of this.#hiddenOverlaySentinels) {
 			if (visibleSentinels.has(sentinel)) continue;
 			if (nativeText.includes(sentinel)) {
-				this.#fail("stale overlay sentinel", op, before, after, index, { sentinel });
+				this.#fail("stale overlay sentinel", op, before, after, index, {
+					sentinel,
+				});
 			}
 		}
 	}
@@ -3064,11 +3204,18 @@ export function expectedFrameFromLines(lines: readonly string[], width: number,
 		const cleanLine = markerIndex === -1 ? line : removeCursorMarkers(line);
 		backgroundColumns[row] = expectedBackgroundColumns(cleanLine, width);
 		if (markerIndex !== -1 && cursor === null && row >= viewportTop) {
-			cursor = { row: row - viewportTop, col: visibleWidth(line.slice(0, markerIndex)) };
+			cursor = {
+				row: row - viewportTop,
+				col: visibleWidth(line.slice(0, markerIndex)),
+			};
 		}
 		stripped[row] = cleanLine;
 	}
-	return { frame: stripped.map(line => expectedTerminalLine(line, width)), cursor, backgroundColumns };
+	return {
+		frame: stripped.map(line => expectedTerminalLine(line, width)),
+		cursor,
+		backgroundColumns,
+	};
 }
 
 function expectedBackgroundColumns(line: string, width: number): number[] {
@@ -3135,7 +3282,12 @@ function compositeExpectedOverlays(
 ): string[] {
 	if (overlays.length === 0) return [...lines];
 	const result = [...lines];
-	const rendered: { overlayLines: string[]; row: number; col: number; w: number }[] = [];
+	const rendered: {
+		overlayLines: string[];
+		row: number;
+		col: number;
+		w: number;
+	}[] = [];
 	let minLinesNeeded = result.length;
 	for (const entry of overlays) {
 		if (!isExpectedOverlayVisible(entry, termWidth, termHeight)) continue;
@@ -3145,7 +3297,12 @@ function compositeExpectedOverlays(
 			overlayLines = overlayLines.slice(0, firstLayout.maxHeight);
 		}
 		const layout = resolveExpectedOverlayLayout(entry.options, overlayLines.length, termWidth, termHeight);
-		rendered.push({ overlayLines, row: layout.row, col: layout.col, w: layout.width });
+		rendered.push({
+			overlayLines,
+			row: layout.row,
+			col: layout.col,
+			w: layout.width,
+		});
 		minLinesNeeded = Math.max(minLinesNeeded, layout.row + overlayLines.length);
 	}
 	const workingHeight = Math.max(result.length, minLinesNeeded);
@@ -3180,7 +3337,12 @@ export function resolveExpectedOverlayLayout(
 	const opt = options ?? {};
 	const margin =
 		typeof opt.margin === "number"
-			? { top: opt.margin, right: opt.margin, bottom: opt.margin, left: opt.margin }
+			? {
+					top: opt.margin,
+					right: opt.margin,
+					bottom: opt.margin,
+					left: opt.margin,
+				}
 			: (opt.margin ?? {});
 	const marginTop = Math.max(0, margin.top ?? 0);
 	const marginRight = Math.max(0, margin.right ?? 0);
@@ -3410,12 +3572,18 @@ function snapshotDump(snapshot: Snapshot): JsonObject {
 		view: snapshot.view,
 		viewBackgroundColumns: snapshot.viewBackgroundColumns,
 		frameBackgroundColumns: snapshot.frameBackgroundColumns,
-		position: { baseY: snapshot.position.baseY, viewportY: snapshot.position.viewportY },
+		position: {
+			baseY: snapshot.position.baseY,
+			viewportY: snapshot.position.viewportY,
+		},
 		cursor: cursorObject(snapshot),
 		expectedCursor:
 			snapshot.expectedCursor === null
 				? null
-				: { row: snapshot.expectedCursor.row, col: snapshot.expectedCursor.col },
+				: {
+						row: snapshot.expectedCursor.row,
+						col: snapshot.expectedCursor.col,
+					},
 		redraws: snapshot.redraws,
 		width: snapshot.width,
 		height: snapshot.height,
@@ -3429,12 +3597,18 @@ function snapshotSummary(snapshot: Snapshot): JsonObject {
 		bufferLength: snapshot.buffer.length,
 		view: snapshot.view,
 		viewBackgroundColumns: snapshot.viewBackgroundColumns,
-		position: { baseY: snapshot.position.baseY, viewportY: snapshot.position.viewportY },
+		position: {
+			baseY: snapshot.position.baseY,
+			viewportY: snapshot.position.viewportY,
+		},
 		cursor: cursorObject(snapshot),
 		expectedCursor:
 			snapshot.expectedCursor === null
 				? null
-				: { row: snapshot.expectedCursor.row, col: snapshot.expectedCursor.col },
+				: {
+						row: snapshot.expectedCursor.row,
+						col: snapshot.expectedCursor.col,
+					},
 		redraws: snapshot.redraws,
 		width: snapshot.width,
 		height: snapshot.height,
@@ -3620,7 +3794,9 @@ function parseReplayOperations(): readonly OperationKind[] | null {
 	try {
 		parsed = JSON.parse(fs.readFileSync(path, "utf8"));
 	} catch (error) {
-		throw new Error(`Invalid TUI_STRESS_REPLAY_LOG JSON: ${path}`, { cause: error });
+		throw new Error(`Invalid TUI_STRESS_REPLAY_LOG JSON: ${path}`, {
+			cause: error,
+		});
 	}
 	const entries = Array.isArray(parsed)
 		? parsed
@@ -3756,9 +3932,9 @@ function coreTemplates(): ScenarioTemplate[] {
 			heightChoices: [3, 4, 6],
 		},
 		{
-			// Direct HerdR implements ED3, so a settled width change clears and
-			// replays the source-owned transcript at its new wrap. Streaming
-			// updates may race the resize but must survive that replay exactly once.
+			// Direct HerdR follows the in-place multiplexer resize policy.
+			// Streaming updates may race the resize but must survive the settled
+			// repaint exactly once.
 			name: "darwin-normal-herdr-reflow-stream-small",
 			platform: "darwin",
 			terminalMode: "normal",
@@ -3929,7 +4105,10 @@ function coreTemplates(): ScenarioTemplate[] {
 
 function soakTemplates(): ScenarioTemplate[] {
 	const templates: ScenarioTemplate[] = [];
-	const platformEnvModes: readonly { platform: TestPlatform; envModes: readonly EnvMode[] }[] = [
+	const platformEnvModes: readonly {
+		platform: TestPlatform;
+		envModes: readonly EnvMode[];
+	}[] = [
 		{ platform: "darwin", envModes: ["plain", "tmux", "herdr"] },
 		{ platform: "linux", envModes: ["plain", "tmux", "termux", "vteNoSync"] },
 		{ platform: "win32", envModes: ["plain"] },
@@ -4094,7 +4273,10 @@ async function withPatchedPlatform<T>(platform: Scenario["platform"], run: () =>
 	if (platformPatchDepth > 0) throw new Error("Nested stress platform patching is not supported");
 	platformPatchDepth += 1;
 	const platformDescriptor = Object.getOwnPropertyDescriptor(process, "platform");
-	Object.defineProperty(process, "platform", { configurable: true, value: platform });
+	Object.defineProperty(process, "platform", {
+		configurable: true,
+		value: platform,
+	});
 	try {
 		return await run();
 	} finally {
@@ -4143,7 +4325,11 @@ export async function runStressScenario(scenario: Scenario, options?: { patchEnv
 export async function runWidthEpochOverlayReplayRegression(): Promise<void> {
 	const base = coreTemplates().find(candidate => candidate.name === "darwin-normal-herdr-reflow-stream-small");
 	if (base === undefined) throw new Error("Missing reflow-stream stress template");
-	const template: ScenarioTemplate = { ...base, name: "darwin-normal-tmux-reflow-stream-small", envMode: "tmux" };
+	const template: ScenarioTemplate = {
+		...base,
+		name: "darwin-normal-tmux-reflow-stream-small",
+		envMode: "tmux",
+	};
 	const operations: readonly OperationKind[] = ["resizeWidth", "showOverlay", "streamOne", "streamOne", "hideOverlay"];
 	const scenario = materializeScenario(
 		template,
@@ -4160,7 +4346,11 @@ export async function runWidthEpochOverlayReplayRegression(): Promise<void> {
 export async function runWidthEpochHeightAppendReplayRegression(): Promise<void> {
 	const source = coreTemplates().find(candidate => candidate.name === "darwin-normal-herdr-reflow-stream-small");
 	if (source === undefined) throw new Error("Missing reflow-stream stress template");
-	const base: ScenarioTemplate = { ...source, name: "darwin-normal-tmux-reflow-stream-small", envMode: "tmux" };
+	const base: ScenarioTemplate = {
+		...source,
+		name: "darwin-normal-tmux-reflow-stream-small",
+		envMode: "tmux",
+	};
 	const template: ScenarioTemplate = {
 		...base,
 		columns: 40,
@@ -4204,14 +4394,38 @@ export async function runNoReflowResizeNotificationRegression(): Promise<void> {
 			const processKill = Object.getOwnPropertyDescriptor(process, "kill");
 			const writes: string[] = [];
 
-			Object.defineProperty(process.stdin, "isTTY", { value: true, configurable: true });
-			Object.defineProperty(process.stdout, "isTTY", { value: true, configurable: true });
-			Object.defineProperty(process.stdout, "columns", { value: 100, configurable: true });
-			Object.defineProperty(process.stdout, "rows", { value: 30, configurable: true });
-			Object.defineProperty(process.stdin, "setRawMode", { value: () => process.stdin, configurable: true });
-			Object.defineProperty(process.stdin, "setEncoding", { value: () => process.stdin, configurable: true });
-			Object.defineProperty(process.stdin, "resume", { value: () => process.stdin, configurable: true });
-			Object.defineProperty(process.stdin, "pause", { value: () => process.stdin, configurable: true });
+			Object.defineProperty(process.stdin, "isTTY", {
+				value: true,
+				configurable: true,
+			});
+			Object.defineProperty(process.stdout, "isTTY", {
+				value: true,
+				configurable: true,
+			});
+			Object.defineProperty(process.stdout, "columns", {
+				value: 100,
+				configurable: true,
+			});
+			Object.defineProperty(process.stdout, "rows", {
+				value: 30,
+				configurable: true,
+			});
+			Object.defineProperty(process.stdin, "setRawMode", {
+				value: () => process.stdin,
+				configurable: true,
+			});
+			Object.defineProperty(process.stdin, "setEncoding", {
+				value: () => process.stdin,
+				configurable: true,
+			});
+			Object.defineProperty(process.stdin, "resume", {
+				value: () => process.stdin,
+				configurable: true,
+			});
+			Object.defineProperty(process.stdin, "pause", {
+				value: () => process.stdin,
+				configurable: true,
+			});
 			Object.defineProperty(process.stdout, "write", {
 				value: (chunk: string | Uint8Array) => {
 					writes.push(typeof chunk === "string" ? chunk : Buffer.from(chunk).toString());
@@ -4219,7 +4433,10 @@ export async function runNoReflowResizeNotificationRegression(): Promise<void> {
 				},
 				configurable: true,
 			});
-			Object.defineProperty(process, "kill", { value: () => true, configurable: true });
+			Object.defineProperty(process, "kill", {
+				value: () => true,
+				configurable: true,
+			});
 
 			// Exercises the real ProcessTerminal stdin/stdout pipeline; opt out of
 			// the test-default headless suppression inside the try so the finally