From 15b6d2075ec09e4d8feba1a456ae4206659e941d Mon Sep 17 00:00:00 2001
From: RAJVEER42 <irajveer.bishnoi2310@gmail.com>
Date: Fri, 22 May 2026 02:43:52 +0530
Subject: [PATCH] fix: claude prompt mode signals error on max_tokens
 truncation
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scanBatchWithPrompt used max_tokens: 1024 but never checked
stop_reason on the response. When the API hit the token limit,
extractFindings found no tool_use block and returned { findings: [] }
— identical to a clean empty result. No error was logged, errorCount
stayed at zero, and findings were silently dropped.

Added stop_reason check before extractFindings: a max_tokens response
now returns { error: true } and logs an error, so the batch is counted
as failed and the caller knows findings may be incomplete.
---
 .changeset/lemon-impalas-yawn.md      |  5 +++++
 src/__tests__/adapters/claude.test.ts | 21 +++++++++++++++++++++
 src/adapters/claude.ts                |  5 +++++
 3 files changed, 31 insertions(+)
 create mode 100644 .changeset/lemon-impalas-yawn.md

diff --git a/.changeset/lemon-impalas-yawn.md b/.changeset/lemon-impalas-yawn.md
new file mode 100644
index 0000000..b32b213
--- /dev/null
+++ b/.changeset/lemon-impalas-yawn.md
@@ -0,0 +1,5 @@
+---
+"layne": patch
+---
+
+fix: claude prompt mode now signals an error when the API response is truncated by max_tokens instead of silently returning empty findings
diff --git a/src/__tests__/adapters/claude.test.ts b/src/__tests__/adapters/claude.test.ts
index 9eb5562..f95f85a 100644
--- a/src/__tests__/adapters/claude.test.ts
+++ b/src/__tests__/adapters/claude.test.ts
@@ -221,6 +221,27 @@ describe('runClaude()', () => {
     expect(findings).toEqual([]);
   });
 
+  it('logs an error when stop_reason is max_tokens instead of silently dropping findings', async () => {
+  const consoleSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+  mockReadFile.mockResolvedValueOnce(DUMMY_CONTENT);
+  mockCreate.mockResolvedValueOnce({
+    stop_reason: 'max_tokens',
+    content: [],
+  });
+
+  await runClaude({
+    workspacePath: WORKSPACE,
+    changedFiles:  CHANGED_FILES,
+    toolConfig:    ENABLED_CONFIG,
+  });
+
+  expect(consoleSpy).toHaveBeenCalledWith(
+    expect.stringContaining('max_tokens'),
+  );
+  consoleSpy.mockRestore();
+});
+
+
   it('passes the configured model to the API', async () => {
     mockReadFile.mockResolvedValueOnce(DUMMY_CONTENT);
     mockCreate.mockResolvedValueOnce(cleanResponse());
diff --git a/src/adapters/claude.ts b/src/adapters/claude.ts
index 20a0203..5f6bd27 100644
--- a/src/adapters/claude.ts
+++ b/src/adapters/claude.ts
@@ -218,6 +218,11 @@ async function scanBatchWithPrompt(
       tool_choice: { type: 'any' },
     });
 
+    if (response.stop_reason === 'max_tokens') {
+      console.error('[claude] API error during scan batch (prompt mode): response truncated — max_tokens reached, findings may be incomplete');
+      return { error: true };
+    }
+
     return extractFindings(response.content);
   } catch (err) {
     console.error('[claude] API error during scan batch (prompt mode):', (err as Error).message ?? err);