Merge PR #7740: fix(session): isolate rewind reports by checkpoint cycle (@roboomp)

packages/coding-agent/CHANGELOG.md

@@ -37,6 +37,7 @@
 
 ### Fixed
 
+- Fixed resumed or rebuilt sessions auto-applying a new checkpoint with a stale rewind report from an earlier completed checkpoint cycle ([#7739](https://github.com/can1357/oh-my-pi/issues/7739)).
 - Retried concurrent-request caps with a short backoff without deleting valid Copilot credentials or rotating through sibling accounts.
 - Fixed the default `textVerbosity` setting being forwarded to OpenAI Codex requests unless the user explicitly configures it, preserving Codex's native response-control defaults. ([#4949](https://github.com/can1357/oh-my-pi/issues/4949))
 - Reduced streaming CPU usage by coalescing the cumulative `message_update` deltas of a turn at the event-controller dispatch boundary: at most one streaming-state rebuild runs per ~33ms window instead of one per token, cutting the per-token handler work that dominated the CPU profile of streaming sessions (especially at high token rates) while preserving per-delta speech output. Subscriber dispatch is serialized so a rapid stream tail (`message_update` → `message_end` → `agent_end`) cannot overtake the coalesced flush. ([#7443](https://github.com/can1357/oh-my-pi/issues/7443))

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

@@ -6681,9 +6681,10 @@ export class AgentSession {
 	}
 
 	#extractRewindReport(messages: AgentMessage[]): string | undefined {
-		if (!this.#checkpointState) return undefined;
+		const checkpointState = this.#checkpointState;
+		if (!checkpointState) return undefined;
 		if (this.#pendingRewindReport) return this.#pendingRewindReport;
-		for (let i = messages.length - 1; i >= 0; i--) {
+		for (let i = messages.length - 1; i >= checkpointState.checkpointMessageCount; i--) {
 			const message = messages[i];
 			if (message?.role !== "toolResult" || message.isError) continue;
 			const semanticResult = semanticToolResult(message.toolName, message);

packages/coding-agent/test/agent-session-checkpoint-rewind-branch.test.ts

@@ -267,6 +267,50 @@ describe("AgentSession checkpoint rewind branch context", () => {
 		expect(finalThinking?.thinkingSignature).toBe("sig_after_rewind");
 	});
 
+	it("ignores a completed cycle's rewind result after rebuilding context", async () => {
+		const staleReport = "findings from the previous checkpoint";
+		const currentReport = "findings from the current checkpoint";
+		const { session, mock } = await createHarness([
+			{
+				content: [
+					{ type: "toolCall", id: "call_checkpoint_a", name: "checkpoint", arguments: { goal: "inspect A" } },
+				],
+				stopReason: "toolUse",
+			},
+			{
+				content: [{ type: "toolCall", id: "call_rewind_a", name: "rewind", arguments: { report: staleReport } }],
+				stopReason: "toolUse",
+			},
+			{ content: ["DONE"], stopReason: "stop" },
+		]);
+		await session.prompt("investigate the first checkpoint");
+
+		session.sessionManager.appendMessage({
+			role: "toolResult",
+			toolCallId: "call_rewind_a_late",
+			toolName: "rewind",
+			content: [{ type: "text", text: "rewind requested" }],
+			details: { report: staleReport, rewound: true },
+			isError: false,
+			timestamp: Date.now(),
+		});
+		session.agent.replaceMessages(session.buildDisplaySessionContext().messages);
+
+		mock.push({
+			content: [{ type: "toolCall", id: "call_checkpoint_b", name: "checkpoint", arguments: { goal: "inspect B" } }],
+			stopReason: "toolUse",
+		});
+		mock.push({
+			content: [{ type: "toolCall", id: "call_rewind_b", name: "rewind", arguments: { report: currentReport } }],
+			stopReason: "toolUse",
+		});
+		mock.push({ content: ["DONE"], stopReason: "stop" });
+
+		await session.prompt("investigate the second checkpoint");
+
+		expect(session.getLastCompletedRewind()?.report).toBe(currentReport);
+	});
+
 	it("does not start checkpoint tracking for xdev help envelopes", async () => {
 		const { session } = await createHarness(
 			[