Cap inline attachment context across files (#1498)

Co-authored-by: ghreprimand <203024559+ghreprimand@users.noreply.github.com>

tests/test_document_processor_attachment_budget.py

@@ -0,0 +1,80 @@
+from pathlib import Path
+
+
+class _UploadHandler:
+    def __init__(self, uploads):
+        self.uploads = uploads
+
+    def resolve_upload(self, fid, owner=None):
+        return self.uploads.get(fid)
+
+    def _inside_upload_dir(self, path):
+        return True
+
+    def is_image_file(self, display_name, mime):
+        return False
+
+    def is_audio_file(self, display_name, mime):
+        return False
+
+    def is_document_file(self, display_name, mime):
+        return True
+
+
+def _text_upload(tmp_path: Path, fid: str, body: str):
+    path = tmp_path / f"{fid}.txt"
+    path.write_text(body, encoding="utf-8")
+    return {
+        "path": str(path),
+        "name": path.name,
+        "mime": "text/plain",
+    }
+
+
+def test_multifile_inline_attachment_budget_keeps_later_files_visible(tmp_path, monkeypatch):
+    import src.document_processor as dp
+
+    monkeypatch.setattr(dp, "MAX_INLINE_ATTACHMENT_CHARS", 1200)
+    monkeypatch.setattr(dp, "MIN_INLINE_ATTACHMENT_SLICE", 200)
+    uploads = {
+        "a": _text_upload(tmp_path, "a", "alpha\n" + ("A" * 1000)),
+        "b": _text_upload(tmp_path, "b", "bravo\n" + ("B" * 1000)),
+        "c": _text_upload(tmp_path, "c", "charlie\n" + ("C" * 1000)),
+    }
+
+    content = dp.build_user_content(
+        "How many files do you see?",
+        ["a", "b", "c"],
+        str(tmp_path),
+        _UploadHandler(uploads),
+        owner="tester",
+    )
+
+    assert "=== File: a.txt ===" in content
+    assert "=== File: c.txt ===" not in content
+    assert "Attachment omitted from inline context: b.txt" in content
+    assert "Attachment omitted from inline context: c.txt" in content
+    assert "Ask to inspect this file specifically" in content
+    assert len(content) < 2200
+
+
+def test_inline_attachment_budget_does_not_truncate_small_batches(tmp_path, monkeypatch):
+    import src.document_processor as dp
+
+    monkeypatch.setattr(dp, "MAX_INLINE_ATTACHMENT_CHARS", 5000)
+    uploads = {
+        "a": _text_upload(tmp_path, "a", "alpha"),
+        "b": _text_upload(tmp_path, "b", "bravo"),
+    }
+
+    content = dp.build_user_content(
+        "Summarize these.",
+        ["a", "b"],
+        str(tmp_path),
+        _UploadHandler(uploads),
+        owner="tester",
+    )
+
+    assert "=== File: a.txt ===" in content
+    assert "=== File: b.txt ===" in content
+    assert "Attachment content truncated" not in content