fix(ai): preserved sibling thinking envelopes

Parsed literal thinking envelopes independently before transcript rendering so interleaved thinking blocks do not collapse into one malformed wrapper. Added advisor raw dump regression coverage for sibling literal thinking blocks.\n\nFixes #2700

packages/ai/src/dialect/rendering.ts

@@ -161,20 +161,55 @@ function isAsciiWhitespace(code: number): boolean {
 	return code === 9 || code === 10 || code === 11 || code === 12 || code === 13 || code === 32;
 }
 
-function unwrapDelimitedThinking(open: string, close: string, text: string): string {
-	let start = 0;
-	let end = text.length;
-	let changed = false;
-	while (true) {
-		while (start < end && isAsciiWhitespace(text.charCodeAt(start))) start++;
-		while (end > start && isAsciiWhitespace(text.charCodeAt(end - 1))) end--;
-		if (end - start < open.length + close.length) break;
-		if (!text.startsWith(open, start) || !text.startsWith(close, end - close.length)) break;
-		start += open.length;
-		end -= close.length;
-		changed = true;
+function trimAsciiStart(text: string, start: number, end: number): number {
+	let cursor = start;
+	while (cursor < end && isAsciiWhitespace(text.charCodeAt(cursor))) cursor++;
+	return cursor;
+}
+
+function trimAsciiEnd(text: string, start: number, end: number): number {
+	let cursor = end;
+	while (cursor > start && isAsciiWhitespace(text.charCodeAt(cursor - 1))) cursor--;
+	return cursor;
+}
+
+function findDelimitedThinkingClose(open: string, close: string, text: string, start: number, end: number): number {
+	let depth = 1;
+	let cursor = start;
+	while (cursor < end) {
+		const nextClose = text.indexOf(close, cursor);
+		if (nextClose < 0 || nextClose >= end) return -1;
+		const nextOpen = text.indexOf(open, cursor);
+		if (nextOpen >= 0 && nextOpen < nextClose) {
+			depth++;
+			cursor = nextOpen + open.length;
+			continue;
+		}
+		depth--;
+		if (depth === 0) return nextClose;
+		cursor = nextClose + close.length;
 	}
-	return changed ? text.slice(start, end) : text;
+	return -1;
+}
+
+function unwrapDelimitedThinking(open: string, close: string, text: string): string {
+	const end = trimAsciiEnd(text, 0, text.length);
+	let cursor = trimAsciiStart(text, 0, end);
+	if (cursor >= end || !text.startsWith(open, cursor)) return text;
+
+	const segments: string[] = [];
+	while (cursor < end) {
+		if (!text.startsWith(open, cursor)) return text;
+		const innerStart = cursor + open.length;
+		const innerEnd = findDelimitedThinkingClose(open, close, text, innerStart, end);
+		if (innerEnd < 0) return text;
+
+		const trimmedInnerEnd = trimAsciiEnd(text, innerStart, innerEnd);
+		const trimmedInnerStart = trimAsciiStart(text, innerStart, trimmedInnerEnd);
+		segments.push(unwrapDelimitedThinking(open, close, text.slice(trimmedInnerStart, trimmedInnerEnd)));
+		cursor = trimAsciiStart(text, innerEnd + close.length, end);
+	}
+	return segments.join("\n");
 }
 
 export function renderDelimitedThinking(open: string, close: string, text: string): string {

packages/coding-agent/src/advisor/__tests__/advisor.test.ts

@@ -605,5 +605,26 @@ describe("advisor", () => {
 			expect(md).toContain("Assistant: <thinking>\nCheck logs before accepting container health.\n</thinking>");
 			expect(md).not.toContain("<thinking>\n<thinking>");
 		});
+
+		it("unwraps sibling literal thinking envelopes independently", () => {
+			const md = formatSessionDumpText({
+				messages: [
+					{
+						role: "assistant",
+						content: [
+							{ type: "thinking", thinking: "<thinking>\nfirst\n</thinking>" },
+							{ type: "toolCall", id: "tc-1", name: "read", arguments: { path: "file.ts" } },
+							{ type: "thinking", thinking: "<thinking>\nsecond\n</thinking>" },
+						],
+						timestamp: Date.now(),
+					} as AgentMessage,
+				],
+				tools: [{ name: "read", description: "Read a file", parameters: { type: "object" } }],
+				thinkingLevel: "high",
+			});
+
+			expect(md).toContain("Assistant: <thinking>\nfirst\nsecond\n</thinking>");
+			expect(md).not.toContain("first\n</thinking>\n<thinking>\nsecond");
+		});
 	});
 });