From e86a6ede247b0640064972d710ec8a0b29cb19eb Mon Sep 17 00:00:00 2001
From: Matt Wilkinson <mattwilki17@gmail.com>
Date: Sun, 28 Jun 2026 13:39:02 -0400
Subject: [PATCH] fix(session): drop content-less provider-rejection turns from
 persisted history

A request the provider rejects (e.g. 413 oversized payload) yields a
synthesized assistant turn with empty content and stopReason 'error'.
That turn is written to session.jsonl, so on reload it replays as an
empty assistant turn and re-sends the same rejected context. Keep the
rejection UI-only (pinned error) and out of persisted history so a
reloaded session resumes from the last good turn.
---
 .../coding-agent/src/session/agent-session.ts |  2 ++
 packages/coding-agent/src/session/messages.ts | 13 +++++++++
 .../test/session/empty-error-turn.test.ts     | 29 +++++++++++++++++++
 3 files changed, 44 insertions(+)
 create mode 100644 packages/coding-agent/test/session/empty-error-turn.test.ts

diff --git a/packages/coding-agent/src/session/agent-session.ts b/packages/coding-agent/src/session/agent-session.ts
index f271f21bf..e83e3a20e 100644
--- a/packages/coding-agent/src/session/agent-session.ts
+++ b/packages/coding-agent/src/session/agent-session.ts
@@ -338,6 +338,7 @@ import {
 	demoteInterruptedThinking,
 	INTERRUPTED_THINKING_MESSAGE_TYPE,
 	type InterruptedThinkingDetails,
+	isEmptyErrorTurn,
 	isUserInterruptAbort,
 	type PythonExecutionMessage,
 	readQueueChipText,
@@ -3318,6 +3319,7 @@ export class AgentSession {
 		if (message.role === "assistant") {
 			const assistantMsg = message as AssistantMessage;
 			if (this.#isClassifierRefusal(assistantMsg)) return;
+			if (isEmptyErrorTurn(assistantMsg)) return;
 			if (assistantMsg.stopReason !== "aborted" && assistantMsg.stopReason !== "error" && assistantMsg.usage) {
 				assistantMsg.contextSnapshot = {
 					promptTokens: calculatePromptTokens(assistantMsg.usage),
diff --git a/packages/coding-agent/src/session/messages.ts b/packages/coding-agent/src/session/messages.ts
index f72c829f5..5b6999a3c 100644
--- a/packages/coding-agent/src/session/messages.ts
+++ b/packages/coding-agent/src/session/messages.ts
@@ -183,6 +183,19 @@ export function shouldRenderAbortReason(message: Pick<AssistantMessage, "errorId
 	return !isSilentAbort(message) && !isUserInterruptAbort(message);
 }
 
+/** A provider-rejection turn carrying nothing but the error flag: stopReason
+ *  "error" with no text content and no tool calls — e.g. a request the provider
+ *  rejected before any output (an oversized 413 payload). Persisting it writes an
+ *  empty assistant turn that replays on reload and re-sends the rejected context;
+ *  the error is surfaced live (pinned) instead. A turn that streamed partial text
+ *  or tool calls is NOT empty and stays in history. */
+export function isEmptyErrorTurn(message: Pick<AssistantMessage, "stopReason" | "content">): boolean {
+	if (message.stopReason !== "error") return false;
+	return !message.content.some(
+		block => (block.type === "text" && block.text.trim().length > 0) || block.type === "toolCall",
+	);
+}
+
 /** Sentinel `errorMessage` the agent stamps on any abort that carried no custom
  *  reason (bare `abort()`). Renderers treat it as "no specific reason given". */
 export const GENERIC_ABORT_SENTINEL = "Request was aborted";
diff --git a/packages/coding-agent/test/session/empty-error-turn.test.ts b/packages/coding-agent/test/session/empty-error-turn.test.ts
new file mode 100644
index 000000000..7d256bcc9
--- /dev/null
+++ b/packages/coding-agent/test/session/empty-error-turn.test.ts
@@ -0,0 +1,29 @@
+import { describe, expect, it } from "bun:test";
+import type { AssistantMessage } from "@oh-my-pi/pi-ai";
+import { isEmptyErrorTurn } from "@oh-my-pi/pi-coding-agent/session/messages";
+
+type Turn = Pick<AssistantMessage, "stopReason" | "content">;
+
+const turn = (stopReason: AssistantMessage["stopReason"], content: AssistantMessage["content"]): Turn => ({
+	stopReason,
+	content,
+});
+
+describe("isEmptyErrorTurn", () => {
+	it("flags a content-less provider-rejection turn (the wedge poison that replays on reload)", () => {
+		expect(isEmptyErrorTurn(turn("error", []))).toBe(true);
+		expect(isEmptyErrorTurn(turn("error", [{ type: "text", text: "   " }]))).toBe(true);
+	});
+
+	it("keeps error turns that streamed real text or tool calls", () => {
+		expect(isEmptyErrorTurn(turn("error", [{ type: "text", text: "partial answer" }]))).toBe(false);
+		expect(isEmptyErrorTurn(turn("error", [{ type: "toolCall", id: "c1", name: "bash", arguments: {} }]))).toBe(
+			false,
+		);
+	});
+
+	it("never flags non-error turns, even when empty — only the rejection turn is dropped", () => {
+		expect(isEmptyErrorTurn(turn("stop", []))).toBe(false);
+		expect(isEmptyErrorTurn(turn("aborted", []))).toBe(false);
+	});
+});