feat: implemented token tracking and metadata options for compaction summaries

- Added `CompactionSummaryMessageOptions` interface to support optional fields and metadata in compaction summary messages.
- Included compaction method labels and before-after amount badge rendering in compaction views.
- Updated session maintenance and compaction methods to track and compute post-compaction token counts.
- Updated calls across agent and coding-agent packages to use the new compaction options object.

packages/agent/CHANGELOG.md

@@ -16,6 +16,7 @@
 ### Changed
 
 - Expanded native tokenizer support across catalog models, adding exact embedded token counting for Claude, Qwen 3.5+, DeepSeek V3/V4/R1, Kimi K2/K3, and GLM-5+ models. `Tokenizer` now constructs from a resolved catalog `Model`.
+- `createCompactionSummaryMessage` takes an options object after `(summary, tokensBefore, timestamp)`; `CompactionSummaryMessage` gained optional `method` and `tokensAfter` display metadata.
 
 ## [17.3.8] - 2026-08-19
 

packages/agent/src/compaction/branch-summarization.ts

@@ -191,7 +191,9 @@ function getMessageFromEntry(entry: SessionEntry): AgentMessage | undefined {
 			return createBranchSummaryMessage(entry.summary, entry.fromId, entry.timestamp);
 
 		case "compaction":
-			return createCompactionSummaryMessage(entry.summary, entry.tokensBefore, entry.timestamp, entry.shortSummary);
+			return createCompactionSummaryMessage(entry.summary, entry.tokensBefore, entry.timestamp, {
+				shortSummary: entry.shortSummary,
+			});
 
 		// These don't contribute to conversation content
 		case "thinking_level_change":

packages/agent/src/compaction/messages.ts

@@ -49,6 +49,10 @@ export interface CompactionSummaryMessage {
 	summary: string;
 	shortSummary?: string;
 	tokensBefore: number;
+	/** Estimated context tokens after the rewrite (display metadata). */
+	tokensAfter?: number;
+	/** Harness compaction method that produced this summary (display metadata). */
+	method?: string;
 	providerPayload?: ProviderPayload;
 	/** Runtime-only ordered archive blocks for snapcompact: old text region,
 	 *  imaged middle, then new text region. When present, `summary` is already
@@ -99,16 +103,26 @@ export function createBranchSummaryMessage(summary: string, fromId: string, time
 	};
 }
 
+/** Optional metadata for {@link createCompactionSummaryMessage}. */
+export interface CompactionSummaryMessageOptions {
+	shortSummary?: string;
+	providerPayload?: ProviderPayload;
+	images?: ImageContent[];
+	blocks?: (TextContent | ImageContent)[];
+	warning?: string;
+	/** Harness compaction method that produced this summary (e.g. "remote", "soft", "handoff"). */
+	method?: string;
+	/** Estimated context tokens after the rewrite, for display alongside `tokensBefore`. */
+	tokensAfter?: number;
+}
+
 export function createCompactionSummaryMessage(
 	summary: string,
 	tokensBefore: number,
 	timestamp: string,
-	shortSummary?: string,
-	providerPayload?: ProviderPayload,
-	images?: ImageContent[],
-	blocks?: (TextContent | ImageContent)[],
-	warning?: string,
+	options: CompactionSummaryMessageOptions = {},
 ): CompactionSummaryMessage {
+	const { shortSummary, providerPayload, images, blocks, warning, method, tokensAfter } = options;
 	const imageBlocks =
 		blocks?.filter((block): block is ImageContent => block.type === "image") ??
 		(images && images.length > 0 ? images : undefined);
@@ -117,6 +131,8 @@ export function createCompactionSummaryMessage(
 		summary,
 		shortSummary,
 		tokensBefore,
+		tokensAfter,
+		method,
 		providerPayload,
 		blocks: blocks && blocks.length > 0 ? blocks : undefined,
 		images: imageBlocks && imageBlocks.length > 0 ? imageBlocks : undefined,

packages/agent/test/snapcompact-frames.test.ts

@@ -14,28 +14,16 @@ describe("compaction summary message with snapcompact frames", () => {
 
 	it("countMessage charges per attached frame", () => {
 		const bare = createCompactionSummaryMessage("summary text", 1000, new Date().toISOString());
-		const withFrames = createCompactionSummaryMessage(
-			"summary text",
-			1000,
-			new Date().toISOString(),
-			undefined,
-			undefined,
-			images,
-		);
+		const withFrames = createCompactionSummaryMessage("summary text", 1000, new Date().toISOString(), { images });
 		expect(tokenizer.countMessage(withFrames) - tokenizer.countMessage(bare)).toBe(
 			2 * snapcompact.FRAME_TOKEN_ESTIMATE,
 		);
 	});
 
 	it("defaultConvertToLlm appends frames as image blocks after the summary text", () => {
-		const message = createCompactionSummaryMessage(
-			"the snapcompact archive",
-			1000,
-			new Date().toISOString(),
-			undefined,
-			undefined,
+		const message = createCompactionSummaryMessage("the snapcompact archive", 1000, new Date().toISOString(), {
 			images,
-		);
+		});
 		const [converted] = defaultConvertToLlm([message]);
 		expect(converted.role).toBe("user");
 		const content = converted.content as Array<{ type: string; text?: string; data?: string }>;

packages/coding-agent/CHANGELOG.md

@@ -20,6 +20,7 @@
 ### Changed
 
 - Revamped the todo HUD — overall progress renders along the tree-spine connector with smooth completion transitions.
+- Compaction divider now names the maintenance method that fired (`remote-compacted`, `soft-compacted`, `handed-off`, `snap-compacted`) and shows the before → after context size (e.g. `256K→20K`).
 - `/handoff` (and automatic handoff compaction) now compacts in place, replacing the session context instead of forking a new session.
 - Compaction method priorities — `compaction.methodOrder` takes an ordered preference list (e.g. `[remote, snap]` uses remote compaction where the provider supports it, such as OpenAI, and snap everywhere else), replacing `compaction.strategy`/`compaction.remoteEnabled`.
 - Unified inline overlays and selectors (model picker, settings, `/cleanse`) into one titled rounded-box panel style.

packages/coding-agent/src/modes/components/compaction-summary-message.ts

@@ -1,7 +1,23 @@
 import { Box, type Component, Markdown } from "@oh-my-pi/pi-tui";
+import { formatNumber } from "@oh-my-pi/pi-utils";
 import { getMarkdownTheme, theme } from "../../modes/theme/theme";
 import type { BranchSummaryMessage, CompactionSummaryMessage, CustomMessage } from "../../session/messages";
 
+/** Divider labels per compaction method; unknown/legacy methods fall back to "compacted". */
+const COMPACTION_METHOD_LABELS: Record<string, string> = {
+	remote: "remote-compacted",
+	soft: "soft-compacted",
+	handoff: "handed-off",
+	snapcompact: "snap-compacted",
+	shake: "shaken",
+};
+
+/** `256K→20K` amount badge, or undefined when the entry predates `tokensAfter`. */
+function compactionAmount(message: CompactionSummaryMessage): string | undefined {
+	if (message.tokensAfter === undefined || message.tokensBefore <= 0) return undefined;
+	return `${formatNumber(message.tokensBefore)}→${formatNumber(message.tokensAfter)}`;
+}
+
 interface SummaryDividerOptions {
 	label: () => string;
 	detailMarkdown: () => string;
@@ -76,9 +92,12 @@ class SummaryDividerComponent implements Component {
 /**
  * Compaction point in the transcript, rendered as a slim horizontal divider:
  *
- *   ──────── 📷 compacted · ctrl+o ────────
+ *   ──────── 📷 remote-compacted · 256K→20K · ctrl+o ────────
  *
- * The conversation above the divider stays visible (display transcript keeps
+ * The label names the maintenance method that fired (remote/soft/handoff/
+ * snapcompact; "compacted" for legacy or extension-provided entries) and the
+ * before → after context amounts when the entry recorded them. The
+ * conversation above the divider stays visible (display transcript keeps
  * full history); only the LLM context was reset. Expanding (ctrl+o) reveals
  * the compaction summary below the divider.
  */
@@ -89,14 +108,20 @@ export class CompactionSummaryMessageComponent implements Component {
 		this.#divider = new SummaryDividerComponent({
 			// A dead-end warning stamped by the progress guard badges the bar;
 			// the full text lives in the ctrl+o detail block below.
-			label: () =>
-				this.message.warning
-					? `${theme.icon.camera} compacted ${theme.fg("warning", theme.icon.warning)}`
-					: `${theme.icon.camera} compacted`,
+			label: () => this.#label(),
 			detailMarkdown: () => this.#detailMarkdown(),
 		});
 	}
 
+	#label(): string {
+		const name = (this.message.method && COMPACTION_METHOD_LABELS[this.message.method]) || "compacted";
+		let label = `${theme.icon.camera} ${name}`;
+		const amount = compactionAmount(this.message);
+		if (amount) label += `${theme.sep.dot}${amount}`;
+		if (this.message.warning) label += ` ${theme.fg("warning", theme.icon.warning)}`;
+		return label;
+	}
+
 	setExpanded(expanded: boolean): void {
 		this.#divider.setExpanded(expanded);
 	}
@@ -110,7 +135,10 @@ export class CompactionSummaryMessageComponent implements Component {
 	}
 
 	#detailMarkdown(): string {
-		const tokenStr = this.message.tokensBefore.toLocaleString();
+		const tokenStr =
+			this.message.tokensAfter !== undefined
+				? `${this.message.tokensBefore.toLocaleString()} to ${this.message.tokensAfter.toLocaleString()}`
+				: this.message.tokensBefore.toLocaleString();
 		const frameCount = this.message.images?.length ?? 0;
 		const frameNote =
 			frameCount > 0 ? `\n\n_${frameCount} snapcompact frame${frameCount === 1 ? "" : "s"} attached_` : "";
@@ -129,7 +157,7 @@ export class HandoffSummaryMessageComponent implements Component {
 
 	constructor(private readonly message: CustomMessage<unknown>) {
 		this.#divider = new SummaryDividerComponent({
-			label: () => `${theme.icon.context} handoff`,
+			label: () => `${theme.icon.context} handed-off`,
 			detailMarkdown: () => this.#detailMarkdown(),
 		});
 	}

packages/coding-agent/src/session/session-advisors.ts

@@ -1501,7 +1501,7 @@ export class SessionAdvisors {
 		// only assistants appended afterward can become the next usage anchor.
 		const advisorUsageAnchorStartIndex = preparation.recentMessages.length + 1;
 		const summaryMessage = {
-			...createCompactionSummaryMessage(summary, tokensBefore, new Date().toISOString(), shortSummary),
+			...createCompactionSummaryMessage(summary, tokensBefore, new Date().toISOString(), { shortSummary }),
 			firstKeptEntryId,
 			advisorUsageAnchorStartIndex,
 		} satisfies AdvisorCompactionSummaryMessage;

packages/coding-agent/src/session/session-context.ts

@@ -372,11 +372,13 @@ export function buildSessionContext(
 						active ? entry.summary : SUPERSEDED_COMPACTION_SUMMARY,
 						entry.tokensBefore,
 						entry.timestamp,
-						active ? entry.shortSummary : SUPERSEDED_COMPACTION_SHORT_SUMMARY,
-						undefined,
-						undefined,
-						snapcompactHistoryBlocksForContext(snapcompactArchive, options),
-						entry.warning,
+						{
+							shortSummary: active ? entry.shortSummary : SUPERSEDED_COMPACTION_SHORT_SUMMARY,
+							blocks: snapcompactHistoryBlocksForContext(snapcompactArchive, options),
+							warning: entry.warning,
+							method: entry.method,
+							tokensAfter: entry.tokensAfter,
+						},
 					),
 				);
 			} else {
@@ -414,11 +416,14 @@ export function buildSessionContext(
 			compaction.summary,
 			compaction.tokensBefore,
 			compaction.timestamp,
-			compaction.shortSummary,
-			providerPayload,
-			undefined,
-			snapcompactHistoryBlocksForContext(snapcompactArchive, options),
-			compaction.warning,
+			{
+				shortSummary: compaction.shortSummary,
+				providerPayload,
+				blocks: snapcompactHistoryBlocksForContext(snapcompactArchive, options),
+				warning: compaction.warning,
+				method: compaction.method,
+				tokensAfter: compaction.tokensAfter,
+			},
 		);
 		// Agent context (non-transcript): summary first so the LLM sees the
 		// compacted context before recent messages.

packages/coding-agent/src/session/session-entries.ts

@@ -1,6 +1,7 @@
 import type { AgentMessage } from "@oh-my-pi/pi-agent-core";
 import type { ImageContent, MessageAttribution, ServiceTierByFamily, TextContent } from "@oh-my-pi/pi-ai";
 import type { StructuredSubagentSchemaMode } from "../task/types";
+import type { CompactionMethod } from "./compaction-methods";
 
 export const CURRENT_SESSION_VERSION = 3;
 
@@ -99,6 +100,10 @@ export interface CompactionEntry<T = unknown> extends SessionEntryBase {
 	shortSummary?: string;
 	firstKeptEntryId: string;
 	tokensBefore: number;
+	/** Estimated context tokens after the rewrite (display metadata). */
+	tokensAfter?: number;
+	/** Method that produced this entry; absent on legacy sessions and extension-provided compactions. */
+	method?: CompactionMethod;
 	/** Extension-specific data (e.g., ArtifactIndex, version markers for structured compaction) */
 	details?: T;
 	/** Hook-provided data to persist across compaction */

packages/coding-agent/src/session/session-maintenance.ts

@@ -971,6 +971,7 @@ export class SessionMaintenance {
 				details,
 				fromExtension,
 				preserveData,
+				method: fromExtension ? undefined : selectedMethod,
 				codexCompaction,
 				advisorResetReason: "compact",
 			});
@@ -1101,6 +1102,7 @@ export class SessionMaintenance {
 			details,
 			fromExtension: false,
 			preserveData: undefined,
+			method: "handoff",
 			codexCompaction: undefined,
 			advisorResetReason: "handoff",
 		});
@@ -1310,6 +1312,7 @@ export class SessionMaintenance {
 		details: unknown;
 		fromExtension: boolean;
 		preserveData: Record<string, unknown> | undefined;
+		method: CompactionMethod | undefined;
 		codexCompaction: CodexCompactionContext | undefined;
 		advisorResetReason: string;
 		detachExtensionEmit?: boolean;
@@ -1319,9 +1322,13 @@ export class SessionMaintenance {
 			args.shortSummary,
 			args.firstKeptEntryId,
 			args.tokensBefore,
-			args.details,
-			args.fromExtension,
-			args.preserveData,
+			{
+				details: args.details,
+				fromExtension: args.fromExtension,
+				preserveData: args.preserveData,
+				method: args.method,
+				tokensAfter: this.#projectCompactedContextTokens(args),
+			},
 		);
 		const newEntries = this.#host.sessionManager.getEntries();
 		const sessionContext = this.#host.buildDisplaySessionContext();
@@ -2164,10 +2171,10 @@ export class SessionMaintenance {
 			result.summary,
 			result.tokensBefore,
 			new Date().toISOString(),
-			result.shortSummary,
-			undefined,
-			undefined,
-			blocks,
+			{
+				shortSummary: result.shortSummary,
+				blocks,
+			},
 		);
 		let tokens =
 			computeNonMessageTokens(this.#host.nonMessageTokenSource(), this.#tokenizer) +
@@ -2176,6 +2183,40 @@ export class SessionMaintenance {
 		return tokens;
 	}
 
+	/**
+	 * Estimated context tokens after a compaction commit: fixed non-message
+	 * overhead + the summary message (with any snapcompact frames re-attached)
+	 * + every message from `firstKeptEntryId` to the branch leaf. Mirrors the
+	 * post-commit context rebuild; persisted as `tokensAfter` on the entry so
+	 * the transcript divider can show the before → after amounts.
+	 */
+	#projectCompactedContextTokens(args: {
+		summary: string;
+		shortSummary: string | undefined;
+		tokensBefore: number;
+		firstKeptEntryId: string;
+		preserveData: Record<string, unknown> | undefined;
+	}): number {
+		const archive = snapcompact.getPreservedArchive(args.preserveData);
+		const blocks = archive
+			? snapcompact.historyBlocks(archive, { maxFrameDataBytes: snapcompact.FRAME_DATA_BYTES_BUDGET })
+			: undefined;
+		const summaryMessage = createCompactionSummaryMessage(args.summary, args.tokensBefore, new Date().toISOString(), {
+			shortSummary: args.shortSummary,
+			blocks,
+		});
+		let tokens =
+			computeNonMessageTokens(this.#host.nonMessageTokenSource(), this.#tokenizer) +
+			this.#tokenizer.countMessage(summaryMessage);
+		let inKeptRegion = false;
+		for (const entry of this.#host.sessionManager.getBranch()) {
+			if (entry.id === args.firstKeptEntryId) inKeptRegion = true;
+			if (!inKeptRegion) continue;
+			if (entry.type === "message") tokens += this.#tokenizer.countMessage(entry.message);
+		}
+		return tokens;
+	}
+
 	/**
 	 * Post-maintenance progress check for the context-full / snapcompact tail.
 	 *
@@ -2499,9 +2540,18 @@ export class SessionMaintenance {
 			result.shortSummary,
 			result.firstKeptEntryId,
 			result.tokensBefore,
-			result.details,
-			false,
-			result.preserveData,
+			{
+				details: result.details,
+				preserveData: result.preserveData,
+				method: "snapcompact",
+				tokensAfter: this.#projectCompactedContextTokens({
+					summary: result.summary,
+					shortSummary: result.shortSummary,
+					tokensBefore: result.tokensBefore,
+					firstKeptEntryId: result.firstKeptEntryId,
+					preserveData: result.preserveData,
+				}),
+			},
 		);
 		const sessionContext = this.#host.buildDisplaySessionContext();
 		this.#host.agent.replaceMessages(sessionContext.messages);
@@ -2698,6 +2748,7 @@ export class SessionMaintenance {
 					preserveData: armedSpec.result.preserveData,
 					fromExtension: false,
 					codexCompaction: armedSpec.codexCompaction,
+					method: armedSpec.method,
 					action,
 					reason,
 					willRetry,
@@ -3284,6 +3335,7 @@ export class SessionMaintenance {
 				preserveData,
 				fromExtension,
 				codexCompaction,
+				method: fromExtension ? undefined : method,
 				action,
 				reason,
 				willRetry,
@@ -3375,6 +3427,7 @@ export class SessionMaintenance {
 		preserveData: Record<string, unknown> | undefined;
 		fromExtension: boolean;
 		codexCompaction: CodexCompactionContext | undefined;
+		method: CompactionMethod | undefined;
 		action: "context-full" | "handoff" | "snapcompact" | "remote";
 		reason: "overflow" | "threshold" | "idle" | "incomplete";
 		willRetry: boolean;
@@ -3412,6 +3465,7 @@ export class SessionMaintenance {
 			fromExtension: args.fromExtension,
 			preserveData: args.preserveData,
 			codexCompaction: args.codexCompaction,
+			method: args.method,
 			advisorResetReason: "auto-compaction",
 			detachExtensionEmit: detachPostCommit,
 		});

packages/coding-agent/src/session/session-manager.ts

@@ -21,6 +21,7 @@ import {
 import type { StructuredSubagentSchemaMode } from "../task/types";
 import { ArtifactManager } from "./artifacts";
 import { type BlobPutOptions, type BlobPutResult, BlobStore } from "./blob-store";
+import type { CompactionMethod } from "./compaction-methods";
 import {
 	type BashExecutionMessage,
 	type CustomMessage,
@@ -2240,9 +2241,13 @@ export class SessionManager {
 		shortSummary: string | undefined,
 		firstKeptEntryId: string,
 		tokensBefore: number,
-		details?: T,
-		fromExtension?: boolean,
-		preserveData?: Record<string, unknown>,
+		options: {
+			details?: T;
+			fromExtension?: boolean;
+			preserveData?: Record<string, unknown>;
+			method?: CompactionMethod;
+			tokensAfter?: number;
+		} = {},
 	): string {
 		const entry: CompactionEntry<T> = {
 			type: "compaction",
@@ -2251,9 +2256,11 @@ export class SessionManager {
 			shortSummary,
 			firstKeptEntryId,
 			tokensBefore,
-			details,
-			fromExtension,
-			preserveData,
+			tokensAfter: options.tokensAfter,
+			method: options.method,
+			details: options.details,
+			fromExtension: options.fromExtension,
+			preserveData: options.preserveData,
 		};
 		this.#recordEntry(entry);
 		return entry.id;

packages/coding-agent/test/agent-session-snapcompact-frame-dead-end.test.ts

@@ -160,9 +160,10 @@ describe("AgentSession snapcompact frame dead-end rescue", () => {
 				"stale snapcompact archive",
 				userEntryId,
 				150_000,
-				{ readFiles: ["src/a.ts"], modifiedFiles: ["src/b.ts"] },
-				false,
-				makeArchivePreserveData(options.frameCount),
+				{
+					details: { readFiles: ["src/a.ts"], modifiedFiles: ["src/b.ts"] },
+					preserveData: makeArchivePreserveData(options.frameCount),
+				},
 			);
 		}
 

packages/coding-agent/test/modes/components/compaction-divider.test.ts

@@ -20,7 +20,7 @@ const SUMMARY = "Earlier the user fixed the login TTL bug.";
 
 function makeComponent(images?: ImageContent[]): CompactionSummaryMessageComponent {
 	return new CompactionSummaryMessageComponent(
-		createCompactionSummaryMessage(SUMMARY, 84000, new Date().toISOString(), undefined, undefined, images),
+		createCompactionSummaryMessage(SUMMARY, 84000, new Date().toISOString(), { images }),
 	);
 }
 
@@ -36,6 +36,29 @@ describe("CompactionSummaryMessageComponent", () => {
 		expect(rule).not.toContain(SUMMARY);
 	});
 
+	it("names the compaction method and the before → after amounts on the divider", () => {
+		const component = new CompactionSummaryMessageComponent(
+			createCompactionSummaryMessage(SUMMARY, 256_000, new Date().toISOString(), {
+				method: "remote",
+				tokensAfter: 20_000,
+			}),
+		);
+		const rule = Bun.stripANSI(component.render(80)[1]);
+		expect(rule).toContain("remote-compacted");
+		expect(rule).toContain("256K→20K");
+		expect(rule).toContain("ctrl+o");
+	});
+
+	it("labels a handoff-method compaction as handed-off", () => {
+		const component = new CompactionSummaryMessageComponent(
+			createCompactionSummaryMessage(SUMMARY, 84_000, new Date().toISOString(), { method: "handoff" }),
+		);
+		const rule = Bun.stripANSI(component.render(80)[1]);
+		expect(rule).toContain("handed-off");
+		// No tokensAfter recorded → no amount badge.
+		expect(rule).not.toContain("→");
+	});
+
 	it("expanded: reveals the summary (and snapcompact frame count) below the divider", () => {
 		const component = makeComponent([{ type: "image", data: "ZmFrZQ==", mimeType: "image/png" }]);
 		component.setExpanded(true);

packages/coding-agent/test/modes/components/compaction-summary-message.test.ts

@@ -39,7 +39,7 @@ describe("handoff summary divider", () => {
 
 		expect(component).toBeInstanceOf(HandoffSummaryMessageComponent);
 		const collapsed = Bun.stripANSI(component!.render(80).join("\n"));
-		expect(collapsed).toContain("handoff");
+		expect(collapsed).toContain("handed-off");
 		expect(collapsed).toContain("ctrl+o");
 		expect(collapsed).not.toContain("[handoff]");
 		expect(collapsed).not.toContain("Continue the resize fix");

packages/coding-agent/test/session-manager/large-session-memory.test.ts

@@ -82,15 +82,9 @@ describe("large session memory guards", () => {
 				textTail: "frame",
 			},
 		};
-		const firstCompactionId = session.appendCompaction(
-			firstSummary,
-			undefined,
-			firstKeptEntryId,
-			1000,
-			undefined,
-			undefined,
-			firstPreserve,
-		);
+		const firstCompactionId = session.appendCompaction(firstSummary, undefined, firstKeptEntryId, 1000, {
+			preserveData: firstPreserve,
+		});
 		const rewindId = session.appendMessage({ role: "user", content: "between compactions", timestamp: 3 });
 		session.appendCompaction(secondSummary, undefined, rewindId, 2000);
 		await session.flush();
@@ -188,15 +182,9 @@ describe("large session memory guards", () => {
 
 		const branchACompactionSummary = `branch-a-${"x".repeat(1024)}`;
 		const branchAPreserve = { openaiRemoteCompaction: { provider: "anthropic", replacementHistory: [] } };
-		session.appendCompaction(
-			branchACompactionSummary,
-			undefined,
-			rootId,
-			1000,
-			undefined,
-			undefined,
-			branchAPreserve,
-		);
+		session.appendCompaction(branchACompactionSummary, undefined, rootId, 1000, {
+			preserveData: branchAPreserve,
+		});
 		const branchACompactionId = session.getLeafId();
 		if (!branchACompactionId) throw new Error("Expected branch A compaction id");
 

packages/coding-agent/test/shake.test.ts

@@ -219,10 +219,13 @@ describe("AgentSession shake", () => {
 			seedHeavyToolResult("X".repeat(20_000));
 			const firstKeptEntryId = sessionManager.getBranch()[0]?.id;
 			if (!firstKeptEntryId) throw new Error("Expected seeded branch");
-			sessionManager.appendCompaction("remote summary", undefined, firstKeptEntryId, 10_000, {}, false, {
-				openaiRemoteCompaction: {
-					provider: "openai",
-					replacementHistory: [],
+			sessionManager.appendCompaction("remote summary", undefined, firstKeptEntryId, 10_000, {
+				details: {},
+				preserveData: {
+					openaiRemoteCompaction: {
+						provider: "openai",
+						replacementHistory: [],
+					},
 				},
 			});
 			sessionManager.appendMessage({