fix(context): retain live-context notices across append-only turns

packages/coding-agent/docs/context-management.md

@@ -6,6 +6,17 @@ conversation; the canonical session history remains intact. CLM uses the
 configured model and retains native summary compaction and provider-overflow
 recovery as fallbacks.
 
+## Request notice stability
+
+Working-context status and pressure notices remain at their original positions
+in the request view during append-only conversation turns. They are not written
+to the canonical transcript. Retries reuse the same notice content and timestamp;
+new tool results and user messages follow previously issued notices. An edited,
+shortened, or different context projection clears the retained notices so a
+branch switch or compaction does not replay stale advice into the new context.
+This preserves ordinary prompt-prefix reuse without preventing intentional
+context edits.
+
 ## Select a compression mode
 
 No flag or configuration change is needed to use CLM. An existing explicit

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

@@ -78,6 +78,7 @@ import {
 	type LiveContextOutcome,
 	type LiveContextStatus,
 } from "./compaction/live-context/manager.ts";
+import { StableContextNotices } from "./compaction/live-context/stable-notices.ts";
 import { DEFAULT_THINKING_LEVEL, THINKING_LEVEL_OPTIONS } from "./defaults.ts";
 import { exportSessionToHtml, type ToolHtmlRenderer } from "./export-html/index.ts";
 import { createToolHtmlRenderer } from "./export-html/tool-renderer.ts";
@@ -882,6 +883,7 @@ export class AgentSession {
 
 	private _installLiveContext(): void {
 		const transform = this.agent.transformContext;
+		const notices = new StableContextNotices();
 		this.agent.transformContext = async (raw, signal) => {
 			const live = this._getLiveContext();
 			if (!live) return transform ? transform(raw, signal) : raw;
@@ -911,9 +913,7 @@ export class AgentSession {
 				this.model?.contextWindow ?? 0,
 				guidanceOptions,
 			);
-			return notice || pressure
-				? [...messages, ...(notice ? [notice] : []), ...(pressure ? [pressure] : [])]
-				: messages;
+			return notices.project(messages, [...(notice ? [notice] : []), ...(pressure ? [pressure] : [])]);
 		};
 		const stream = this.agent.streamFunction;
 		this._liveContextBaseStream = stream;

packages/coding-agent/src/core/compaction/live-context/stable-notices.ts

@@ -0,0 +1,28 @@
+import type { AgentMessage } from "@step-harness/agent-core";
+
+/** Keeps request-only notices at their original boundary during append-only turns. */
+export class StableContextNotices {
+	private previous: string[] = [];
+	private notices: { index: number; message: AgentMessage }[] = [];
+
+	project(messages: AgentMessage[], added: AgentMessage[]): AgentMessage[] {
+		const fingerprints = messages.map((message) => JSON.stringify(message));
+		// A branch switch, compaction or edited projection starts a new context epoch.
+		// Never replay notices belonging to a different history into that epoch.
+		if (this.previous.some((value, index) => fingerprints[index] !== value)) {
+			this.notices = [];
+		}
+		this.previous = fingerprints;
+		for (const message of added) this.notices.push({ index: messages.length, message });
+		if (this.notices.length === 0) return messages;
+
+		const result: AgentMessage[] = [];
+		let start = 0;
+		for (const notice of this.notices) {
+			result.push(...messages.slice(start, notice.index), notice.message);
+			start = notice.index;
+		}
+		result.push(...messages.slice(start));
+		return result;
+	}
+}

packages/coding-agent/test/stable-context-notices.test.ts

@@ -0,0 +1,54 @@
+import type { AgentMessage } from "@step-harness/agent-core";
+import { describe, expect, it } from "vitest";
+import { StableContextNotices } from "../src/core/compaction/live-context/stable-notices.ts";
+
+const user = (content: string, timestamp = 1): AgentMessage => ({ role: "user", content, timestamp });
+const notice = (content: string): AgentMessage => ({
+	role: "custom",
+	customType: "live-context-status",
+	display: false,
+	content,
+	timestamp: 123,
+});
+
+describe("stable request context notices", () => {
+	it("retains a one-shot notice before the newly appended conversation", () => {
+		const state = new StableContextNotices();
+		const raw = [user("read A")];
+		const notification = notice("pressure");
+		const first = state.project(raw, [notification]);
+		const next = state.project([...raw, user("continue", 2)], []);
+		expect(next.slice(0, first.length)).toEqual(first);
+		expect(next).toEqual([...raw, notification, user("continue", 2)]);
+		expect(raw).toEqual([user("read A")]);
+	});
+
+	it("keeps multiple notifications in order and does not duplicate them on retries", () => {
+		const state = new StableContextNotices();
+		const raw = [user("read A")];
+		const a = notice("accepted");
+		const b = notice("pressure");
+		const first = state.project(raw, [a, b]);
+		expect(state.project(structuredClone(raw), [])).toEqual(first);
+		const extended = [...raw, user("continue", 2)];
+		const c = notice("another tier");
+		const second = state.project(extended, [c]);
+		expect(second).toEqual([...raw, a, b, extended[1], c]);
+		expect(state.project(extended, [])).toEqual(second);
+	});
+
+	it.each(["edit", "shrink", "branch"])("drops stale notices on a %s context change", (change) => {
+		const state = new StableContextNotices();
+		const raw = [user("old"), user("tail", 2)];
+		state.project(raw, [notice("old pressure")]);
+		const changed = change === "shrink" ? raw.slice(0, 1) : [user(change), raw[1]];
+		const fresh = notice("new epoch");
+		expect(state.project(changed, [fresh])).toEqual([...changed, fresh]);
+		expect(state.project([...changed, user("continue", 3)], [])).toEqual([...changed, fresh, user("continue", 3)]);
+	});
+
+	it("returns the original view when no notification has been issued", () => {
+		const raw = [user("continue")];
+		expect(new StableContextNotices().project(raw, [])).toBe(raw);
+	});
+});

packages/coding-agent/test/suite/agent-session-live-context.test.ts

@@ -35,10 +35,12 @@ describe("AgentSession CLM context integration", () => {
 		await harness.session.prompt("Fix the parser and retain the public API.");
 		await harness.session.prompt("Check progress.");
 		let next: Context | undefined;
+		let sentMessages: Context["messages"] = [];
 		harness.setResponses([
 			fauxAssistantMessage(fauxToolCall("organize_context", {}), { stopReason: "toolUse" }),
 			(context) => {
 				next = context;
+				sentMessages = structuredClone(context.messages);
 				return fauxAssistantMessage("done");
 			},
 		]);
@@ -48,6 +50,16 @@ describe("AgentSession CLM context integration", () => {
 		expect(next!.messages.some((m) => m.role === "toolResult" && m.toolName === "organize_context")).toBe(true);
 		expect(JSON.stringify(harness.sessionManager.getEntries())).toContain("Verbose old exploration");
 		expect(harness.session.getLiveContextStatus()!.revision).toBe(1);
+		expect(JSON.stringify(sentMessages)).toContain("Context revision 1 accepted");
+		harness.setResponses([
+			(context) => {
+				expect(context.messages.slice(0, sentMessages.length)).toEqual(sentMessages);
+				expect(JSON.stringify(context.messages).match(/Context revision 1 accepted/g)).toHaveLength(1);
+				return fauxAssistantMessage("continued");
+			},
+		]);
+		await harness.session.prompt("continue");
+		expect(JSON.stringify(harness.sessionManager.getEntries())).not.toContain('"customType":"live-context-status"');
 	});
 	it("can inspect a large context index and edit it before native threshold compaction", async () => {
 		let h: Harness;