diff --git a/packages/coding-agent/src/modes/interactive/interactive-mode.ts b/packages/coding-agent/src/modes/interactive/interactive-mode.ts
index 3219e0634..3fd3f08ab 100644
--- a/packages/coding-agent/src/modes/interactive/interactive-mode.ts
+++ b/packages/coding-agent/src/modes/interactive/interactive-mode.ts
@@ -3828,20 +3828,18 @@ export class InteractiveMode {
 			const transformations = diagnostic.details?.transformations;
 			if (!Array.isArray(transformations)) continue;
 
-			const dropped = transformations.flatMap((transformation): string[] => {
-				if (typeof transformation !== "object" || transformation === null) return [];
-				const details = transformation as Record<string, unknown>;
-				if (details.type !== "thinking_dropped") return [];
-				const reason = typeof details.reason === "string" ? details.reason : "unknown reason";
-				const location = typeof details.path === "string" ? ` at ${details.path}` : "";
-				return [`${reason}${location}`];
-			});
-			if (dropped.length === 0) continue;
+			const droppedCount = transformations.filter(
+				(transformation) =>
+					typeof transformation === "object" &&
+					transformation !== null &&
+					(transformation as Record<string, unknown>).type === "thinking_dropped",
+			).length;
+			if (droppedCount === 0) continue;
 
-			const noun = dropped.length === 1 ? "thinking block" : `${dropped.length} thinking blocks`;
+			const noun = droppedCount === 1 ? "1 thinking block" : `${droppedCount} thinking blocks`;
 			this.chatContainer.addChild(new Spacer(1));
 			this.chatContainer.addChild(
-				new Text(theme.fg("warning", `Anthropic dropped ${noun}: ${dropped.join("; ")}`), 1, 0),
+				new Text(theme.fg("warning", `Anthropic dropped ${noun} (details in session)`), 1, 0),
 			);
 		}
 	}
diff --git a/packages/coding-agent/test/interactive-mode-assistant-diagnostics.test.ts b/packages/coding-agent/test/interactive-mode-assistant-diagnostics.test.ts
index 30a13efa4..e890cacf4 100644
--- a/packages/coding-agent/test/interactive-mode-assistant-diagnostics.test.ts
+++ b/packages/coding-agent/test/interactive-mode-assistant-diagnostics.test.ts
@@ -32,6 +32,16 @@ const message: AssistantMessage = {
 						path: "messages.2.content.0",
 						reason: "prefix_binding_mismatch",
 					},
+					{
+						type: "thinking_dropped",
+						path: "messages.5.content.0",
+						reason: "prefix_binding_mismatch",
+					},
+					{
+						type: "thinking_dropped",
+						path: "messages.8.content.0",
+						reason: "prefix_binding_mismatch",
+					},
 				],
 			},
 		},
@@ -55,7 +65,7 @@ describe("InteractiveMode assistant diagnostics", () => {
 		};
 		maybeShowAssistantDiagnostics.call(enabled, message);
 		const output = stripAnsi(enabled.chatContainer.render(120).join("\n"));
-		expect(output).toContain("Anthropic dropped thinking block: prefix_binding_mismatch at messages.2.content.0");
+		expect(output).toContain("Anthropic dropped 3 thinking blocks (details in session)");
 
 		const disabled = {
 			chatContainer: new Container(),