v2.2.2-xml-placeholder-reject: drop placeholder XML tool calls at parse time

Reject qwen3.6 spurious <invoke> tails with path "..." or empty args before
they enter toolCalls, preventing duplicate assistant answers. Dropped blocks
append to flushed text; four new xml-parser tests. DEFERRED-WORK §6 for
console.debug → pino cleanup.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/server/src/services/__tests__/xml-parser.test.ts

@@ -270,6 +270,44 @@ describe('extractToolCallBlocks (v1.13.16 — unified extraction)', () => {
     expect(result.flushed).toBe(input);
     expect(result.remaining).toBe('');
   });
+
+  describe('placeholder arg rejection (qwen3.6 answer-then-spurious-tools)', () => {
+    it('rejects <invoke> with path "..." — 0 calls, block in flushed', () => {
+      const block = '<invoke name="view_file"><parameter name="path">...</parameter></invoke>';
+      const result = extractToolCallBlocks(`Answer text.\n${block}`);
+      expect(result.calls).toEqual([]);
+      expect(result.flushed).toContain('Answer text.');
+      expect(result.flushed).toContain(block);
+      expect(result.remaining).toBe('');
+    });
+
+    it('rejects <invoke> with empty path — 0 calls, block in flushed', () => {
+      const block = '<invoke name="view_file"><parameter name="path"></parameter></invoke>';
+      const result = extractToolCallBlocks(block);
+      expect(result.calls).toEqual([]);
+      expect(result.flushed).toBe(block);
+      expect(result.remaining).toBe('');
+    });
+
+    it('rejects <invoke> with path "<path>" — 0 calls', () => {
+      const block = '<invoke name="view_file"><parameter name="path"><path></parameter></invoke>';
+      const result = extractToolCallBlocks(block);
+      expect(result.calls).toEqual([]);
+      expect(result.flushed).toBe(block);
+    });
+
+    it('returns 1 valid call and flushes placeholder block when mixed in same buffer', () => {
+      const valid =
+        '<invoke name="view_file"><parameter name="path">/opt/boocode/README.md</parameter></invoke>';
+      const placeholder =
+        '<invoke name="view_file"><parameter name="path">...</parameter></invoke>';
+      const result = extractToolCallBlocks(`${valid} tail ${placeholder}`);
+      expect(result.calls).toEqual([{ name: 'view_file', args: { path: '/opt/boocode/README.md' } }]);
+      expect(result.flushed).toContain('tail');
+      expect(result.flushed).toContain(placeholder);
+      expect(result.remaining).toBe('');
+    });
+  });
 });
 
 describe('levenshtein', () => {

apps/server/src/services/inference/xml-parser.ts

@@ -24,6 +24,34 @@ export interface ParsedCall {
   args: Record<string, unknown>;
 }
 
+const PLACEHOLDER_LITERALS = new Set(['...', 'placeholder', '<path>', '<file>']);
+const ANGLE_BRACKET_SENTINEL_RE = /^<[^>]+>$/;
+
+/** True when a string arg looks like a model placeholder, not a real path/value. */
+export function isPlaceholderArgValue(value: unknown): boolean {
+  if (typeof value !== 'string') return false;
+  const trimmed = value.trim();
+  if (trimmed === '') return true;
+  if (PLACEHOLDER_LITERALS.has(trimmed)) return true;
+  if (ANGLE_BRACKET_SENTINEL_RE.test(trimmed)) return true;
+  return false;
+}
+
+function hasPlaceholderArgs(args: Record<string, unknown>): boolean {
+  for (const value of Object.values(args)) {
+    if (isPlaceholderArgValue(value)) return true;
+  }
+  return false;
+}
+
+function logRejectedPlaceholder(parsed: ParsedCall): void {
+  // Pure helper — no Fastify logger here (stream-phase.ts stays unchanged).
+  console.debug(
+    { toolName: parsed.name, args: parsed.args },
+    'rejected placeholder tool call at parse time',
+  );
+}
+
 // v1.10.5: Qwen-flavor parser. Tightened in v1.13.16 to tolerate whitespace
 // around `=` (e.g. `<function = view_file>`). Name capture is non-whitespace,
 // non-`>` so a stray space doesn't get absorbed into the function name.
@@ -152,7 +180,14 @@ export function extractToolCallBlocks(buffer: string): ToolCallExtraction {
     const blockEnd = next.closeIdx + next.spec.close.length;
     const block = buffer.slice(next.openIdx, blockEnd);
     const parsed = next.spec.parse(block);
-    if (parsed) calls.push(parsed);
+    if (parsed) {
+      if (hasPlaceholderArgs(parsed.args)) {
+        logRejectedPlaceholder(parsed);
+        flushed += block;
+      } else {
+        calls.push(parsed);
+      }
+    }
     pos = blockEnd;
   }