[code-simplifier] refactor: small clarity tweaks in chunk cursor + device spec

[github-actions]

Overview

This PR applies small readability/consistency tweaks to code that was recently modified, without changing behavior.

Files Simplified

• packages/dds/tree/src/feature-libraries/chunked-forest/basicChunk.ts
  • Rename an internal variable to better reflect meaning (halfHeight → nodeDepth).
  • Remove a non-null assertion in getStackedFieldKey() by using explicit ?? oob() checks.
• packages/runtime/container-runtime/src/containerRuntime.ts
  • Update the (now-stale) comment above getDeviceSpec() to reflect that navigator is required (browser or Node 22+).
  • Make the deviceMemory cast more explicit via a local navigatorWithDeviceMemory variable.

Changes Based On

• fix(tree): track chunkIndex on field entry so getField finds parent #27084 (tree chunk cursor changes)
• Add Node 22 engines enforcement and breaking change changesets #27116 / Simplify getDeviceSpec and navigator test cleanup #27010 (Node 22+ navigator assumptions and related updates)

Testing

Validation could not be executed in this runner because the available Node version is v20.20.2, while the repo requires >=22.22.2.

Commands attempted

• pnpm install --frozen-lockfile
• pnpm run build:fast
• pnpm run test
• pnpm run lint
• pnpm run format:repo

Review Focus

• Confirm no behavior changes (all changes are local refactors / comment updates).
• Confirm the stack indexing logic remains unchanged.

References: §24823297965

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Show patch preview (72 of 72 lines)

From c2598056b8c63c09d6078d725629f3de07791f07 Mon Sep 17 00:00:00 2001
From: GitHub Copilot <223556219+Copilot@users.noreply.github.com>
Date: Thu, 23 Apr 2026 07:50:01 +0000
Subject: [PATCH] refactor: small clarity tweaks

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../feature-libraries/chunked-forest/basicChunk.ts    | 11 ++++++-----
 .../runtime/container-runtime/src/containerRuntime.ts |  8 +++++---
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/packages/dds/tree/src/feature-libraries/chunked-forest/basicChunk.ts b/packages/dds/tree/src/feature-libraries/chunked-forest/basicChunk.ts
index 4ebaa68..08b0e63 100644
--- a/packages/dds/tree/src/feature-libraries/chunked-forest/basicChunk.ts
+++ b/packages/dds/tree/src/feature-libraries/chunked-forest/basicChunk.ts
@@ -178,13 +178,13 @@ export class BasicChunkCursor extends SynchronousCursor implements ChunkedCursor
 	 * their length should always equal the number of node levels traversed.
 	 */
 	private assertChunkStacksMatchNodeDepth(): void {
-		const halfHeight = this.getNodeOnlyHeightFromHeight();
+		const nodeDepth = this.getNodeOnlyHeightFromHeight();
 		assert(
-			this.indexOfChunkStack.length === halfHeight,
+			this.indexOfChunkStack.length === nodeDepth,
 			0x51c /* unexpected indexOfChunkStack */,
 		);
 		assert(
-			this.indexWithinChunkStack.length === halfHeight,
+			this.indexWithinChunkStack.length === nodeDepth,
 			0x51d /* unexpected indexWithinChunkStack */,
 		);
 	}
@@ -199,8 +199,9 @@ export class BasicChunkCursor extends SynchronousCursor implements ChunkedCursor
 
 	private getStackedFieldKey(height: number): FieldKey {
 		assert(height % 2 === 0, 0x51f /* must field height */);
-		// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-		return this.siblingStack[height]![this.indexStack[height]!] as FieldKey;
+		const siblingsAtHeight = this.siblingStack[height] ?? oob();
+		const indexAtHeight = this.indexStack[height] ?? oo
... (truncated)