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9172048a2f
Bedrock Converse rejects text content blocks that are empty OR
whitespace-only (ValidationException: "text content blocks must
contain non-whitespace text"). The prior fix attempt substituted a
single space (" ") for missing content -- but a lone space IS
whitespace, so it was rejected by the exact same validation rule it
was meant to satisfy. This caused a deterministic, unrecoverable
retry-loop failure once any blank/whitespace assistant, tool, or user
turn entered history (most commonly via context-compaction rewriting
a turn to a blank string).
Adds _safe_text()/_EMPTY_TEXT_PLACEHOLDER ("(empty)") and applies it
everywhere a blank text block could reach the wire: user/assistant
content conversion, tool results, the assistant-empty-turn fallback,
and the first/last-message user-alternation padding. System-prompt
blocks are the one exception: blank parts are dropped entirely rather
than placeholder-filled, since a system prompt block should never
carry meaningless placeholder text.
Adds tests/agent/test_bedrock_empty_text_blocks.py (11 tests, was
already present uncommitted -- codifies the exact failing history
from issue #9486 and asserts no blank block ever reaches Bedrock).
Verified against the actual failed request dump from this session
(27-message payload) -- replaying it through the fixed converter now
produces zero blank/whitespace-only blocks.
115 lines
4.4 KiB
Python
115 lines
4.4 KiB
Python
"""Regression tests for Bedrock Converse empty/whitespace text block rejection.
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Bedrock's Converse API raises::
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ValidationException: The model returned the following errors: messages:
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text content blocks must contain non-whitespace text
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for ANY text content block that is empty OR whitespace-only. Anthropic's native
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API tolerates these; Bedrock does not. Such blocks most often appear after
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context compression rewrites an assistant/tool turn into a blank string — once
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in history the block is re-sent on every call and fails deterministically
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(all retries fail identically). Ref: issue #9486.
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These tests assert convert_messages_to_converse never emits a blank text block
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(including inside toolResult content) and never uses a whitespace-only
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placeholder (a lone space would be rejected by the same validation).
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"""
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import pytest
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from agent.bedrock_adapter import (
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convert_messages_to_converse,
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_convert_content_to_converse,
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_safe_text,
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_EMPTY_TEXT_PLACEHOLDER,
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)
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def _iter_text_blocks(msgs):
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"""Yield every text string that will be sent to Bedrock, incl. toolResult."""
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for m in msgs:
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for b in m["content"]:
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if "text" in b:
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yield b["text"]
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if "toolResult" in b:
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for tb in b["toolResult"]["content"]:
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if "text" in tb:
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yield tb["text"]
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def test_placeholder_is_non_whitespace():
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# The core lesson of #9486: a space is whitespace and is itself rejected.
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assert _EMPTY_TEXT_PLACEHOLDER.strip(), "placeholder must be non-whitespace"
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@pytest.mark.parametrize("value", ["", " ", "\n\n", "\t", None])
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def test_safe_text_blank_inputs_become_non_whitespace(value):
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assert _safe_text(value).strip()
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def test_safe_text_preserves_real_content():
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assert _safe_text("hello") == "hello"
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assert _safe_text(" padded ") == " padded " # inner content kept verbatim
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def test_no_blank_blocks_reach_bedrock():
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"""The exact failing history: blank system/assistant/tool/user turns."""
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messages = [
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{"role": "system", "content": "You are helpful."},
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{"role": "system", "content": [{"type": "text", "text": " "}]},
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{"role": "user", "content": "search for foo"},
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{"role": "assistant", "content": "",
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"tool_calls": [{"id": "tc1",
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"function": {"name": "search", "arguments": "{}"}}]},
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{"role": "tool", "tool_call_id": "tc1", "content": ""}, # empty tool output
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{"role": "assistant", "content": " \n\n "}, # whitespace-only (compaction)
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{"role": "user", "content": [{"type": "text", "text": ""}]},
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{"role": "assistant", "content": None},
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]
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_system, msgs = convert_messages_to_converse(messages)
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for text in _iter_text_blocks(msgs):
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assert text.strip(), f"blank text block would be rejected by Bedrock: {text!r}"
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def test_empty_tool_result_gets_placeholder():
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"""A tool that returns no output must not produce a blank toolResult block."""
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messages = [
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{"role": "user", "content": "run it"},
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{"role": "assistant", "content": "",
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"tool_calls": [{"id": "t1", "function": {"name": "sh", "arguments": "{}"}}]},
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{"role": "tool", "tool_call_id": "t1", "content": " "},
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]
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_system, msgs = convert_messages_to_converse(messages)
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tool_msg = next(m for m in msgs
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if any("toolResult" in b for b in m["content"]))
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block = next(b for b in tool_msg["content"] if "toolResult" in b)
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text = block["toolResult"]["content"][0]["text"]
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assert text.strip()
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def test_real_content_is_preserved_alongside_blank_siblings():
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messages = [
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{"role": "user", "content": [
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{"type": "text", "text": " "},
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{"type": "text", "text": "real question"},
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]},
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]
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_system, msgs = convert_messages_to_converse(messages)
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texts = list(_iter_text_blocks(msgs))
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assert "real question" in texts
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assert all(t.strip() for t in texts)
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def test_blank_system_blocks_dropped_not_blanked():
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messages = [
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{"role": "system", "content": [
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{"type": "text", "text": "keep me"},
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{"type": "text", "text": " "},
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]},
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{"role": "user", "content": "hi"},
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]
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system, _msgs = convert_messages_to_converse(messages)
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assert system is not None
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for block in system:
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assert block["text"].strip()
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assert any(b["text"] == "keep me" for b in system)
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