refactor: Export isFinalId from id-compressor internally and reference it in SharedTree

packages/dds/tree/src/core/tree/detachedFieldIndexCodecV1.ts

@@ -5,6 +5,7 @@
 
 import { assert } from "@fluidframework/core-utils/internal";
 import type { IIdCompressor } from "@fluidframework/id-compressor";
+import { isFinalId } from "@fluidframework/id-compressor/internal";
 
 import type { CodecAndSchema, IJsonCodec } from "../../codec/index.js";
 import { brand } from "../../util/index.js";
@@ -46,15 +47,15 @@ class MajorCodec implements IJsonCodec<Major, EncodedRevisionTag> {
 		 * The assert below will fail in such a scenario. This is addressed in the v2 codec.
 		 */
 		assert(
-			id === "root" || id >= 0,
+			id === "root" || isFinalId(id),
 			0x88f /* Expected final id on encode of detached field index revision */,
 		);
 		return id;
 	}
 
 	public decode(major: EncodedRevisionTag): RevisionTag {
 		assert(
-			major === "root" || major >= 0,
+			major === "root" || isFinalId(major),
 			0x890 /* Expected final id on decode of detached field index revision */,
 		);
 		return this.revisionTagCodec.decode(major, {

packages/dds/tree/src/core/tree/detachedFieldIndexCodecV2.ts

@@ -5,7 +5,7 @@
 
 import { assert } from "@fluidframework/core-utils/internal";
 import type { IIdCompressor, StableId } from "@fluidframework/id-compressor";
-import { isStableId } from "@fluidframework/id-compressor/internal";
+import { isFinalId, isStableId } from "@fluidframework/id-compressor/internal";
 
 import type { CodecAndSchema, IJsonCodec } from "../../codec/index.js";
 import type { EncodedRevisionTag, RevisionTagCodec, RevisionTag } from "../rebase/index.js";
@@ -25,7 +25,7 @@ class MajorCodec implements IJsonCodec<Major> {
 		assert(major !== undefined, 0xbfb /* Unexpected undefined revision */);
 		const id = this.revisionTagCodec.encode(major);
 
-		if (id !== "root" && id < 0) {
+		if (id !== "root" && !isFinalId(id)) {
 			/**
 			 * This code path handles the case where the major revision is not finalized.
 			 * This can happen the SharedTree is being attached to an already attached container.
@@ -39,7 +39,9 @@ class MajorCodec implements IJsonCodec<Major> {
 
 	public decode(major: EncodedRevisionTag | StableId): RevisionTag {
 		assert(
-			major === "root" || (typeof major === "string" && isStableId(major)) || major >= 0,
+			major === "root" ||
+				(typeof major === "string" && isStableId(major)) ||
+				(typeof major === "number" && isFinalId(major)),
 			0xbfd /* Expected root, stable, or final compressed id */,
 		);
 		if (typeof major === "string" && isStableId(major)) {

packages/dds/tree/src/feature-libraries/chunked-forest/codec/chunkDecoding.ts

@@ -9,6 +9,7 @@ import type {
 	OpSpaceCompressedId,
 	SessionId,
 } from "@fluidframework/id-compressor";
+import { isFinalId } from "@fluidframework/id-compressor/internal";
 import { v5 as uuidV5 } from "uuid";
 
 import { DiscriminatedUnionDispatcher } from "../../../codec/index.js";
@@ -153,8 +154,10 @@ export function readValue(
 			const idCompressor = idDecodingContext.idCompressor;
 			// OpSpaceCompressedIds are negative, and require a session-id to compute their value.
 			// Due to a bug, we have some special casing for them (see below).
-			// TODO: isFinalId should probably be exported from id-compressor and that could be used to do the narrowing here.
-			if (idDecodingContext.isSummary === true && streamValue < 0) {
+			if (
+				idDecodingContext.isSummary === true &&
+				!isFinalId(streamValue as OpSpaceCompressedId)
+			) {
 				if (
 					idDecodingContext.healUnresolvableIdentifiersOnDecode === true &&
 					idDecodingContext.sharedObjectId !== undefined

packages/dds/tree/src/feature-libraries/chunked-forest/codec/nodeEncoder.ts

@@ -4,7 +4,7 @@
  */
 
 import { assert, fail } from "@fluidframework/core-utils/internal";
-import { isStableId } from "@fluidframework/id-compressor/internal";
+import { isFinalId, isStableId } from "@fluidframework/id-compressor/internal";
 
 import {
 	type FieldKey,
@@ -82,8 +82,7 @@ export class NodeShapeBasedEncoder
 					// This is not the case for forest summaries at the time of writing, so non-finalized ids are instead written using
 					// their long form (by falling through to the original cursor value).
 					// A scenario where such ids can appear in the summary is in the attach summary of a tree being attached to an already-attached container.
-					// TODO: isFinalId should probably be exported from id-compressor and that could be used to do the narrowing here.
-					if (!context.isSummary || opSpaceId >= 0) {
+					if (!context.isSummary || isFinalId(opSpaceId)) {
 						return opSpaceId;
 					}
 				}

packages/runtime/id-compressor/src/identifiers.ts

@@ -8,6 +8,7 @@ import type { OpSpaceCompressedId, SessionSpaceCompressedId } from "./types/inde
 /**
  * A compressed ID that is stable and unique within the scope of network of compressors (i.e. a document).
  * It can only be used/decompressed in the context of the originating document.
+ * @internal
  */
 export type FinalCompressedId = number & {
 	readonly FinalCompressedId: "5d83d1e2-98b7-4e4e-a889-54c855cfa73d";
@@ -27,6 +28,15 @@ export type LocalCompressedId = number & {
 
 /**
  * Returns true if the supplied ID is a final ID.
+ * @internal
+ * @privateRemarks
+ * This should generally not be necessary to use outside of the id-compressor package. It is exported for backwards compatibility for format
+ * choices made in SharedTree (so they can more clearly document their intent).
+ * In general, users of IdCompressor should not care if their ids are finalized or not. They should persist short IDs with the context of the
+ * originator's session ID if it cannot be guaranteed that the ID is finalized.
+ *
+ * Note that the bad assumption that made exporting this function necessary is that all IDs in summaries are finalized. This is not necessarily
+ * the case when an attach summary is generated for a DDS attaching to an already-attached container.
  */
 export function isFinalId(
 	id: SessionSpaceCompressedId | OpSpaceCompressedId,

packages/runtime/id-compressor/src/index.ts

@@ -13,6 +13,7 @@ export {
 	serializeIdCompressor,
 	toIdCompressorWithCore,
 } from "./idCompressor.js";
+export { type FinalCompressedId, isFinalId } from "./identifiers.js";
 export {
 	createSessionId,
 	assertIsStableId,