Bump haystack-ai from 2.31.0 to 3.1.1 in /service in the uv-major group

[dependabot]

Bumps the uv-major group in /service with 1 update: haystack-ai.

Updates haystack-ai from 2.31.0 to 3.1.1

Release notes

Sourced from haystack-ai's releases.

v3.1.1

Release Notes

v3.1.1

Bug Fixes

• The OpenAI Chat Completions and Responses converters no longer raise on an assistant message with no content parts, which a Chat Generator returns when it discards a malformed tool call. It is sent with empty content, which the APIs accept, so the next LLM call goes through. ChatMessage.from_openai_dict_format accepts the same empty content, so such a message round-trips.
• The Hugging Face message converter no longer raises on an assistant message with no content parts, and sends it with empty content instead.

v3.1.1-rc1

Release Notes

v3.1.1-rc1

Bug Fixes

• The OpenAI Chat Completions and Responses converters no longer raise on an assistant message with no content parts, which a Chat Generator returns when it discards a malformed tool call. It is sent with empty content, which the APIs accept, so the next LLM call goes through. ChatMessage.from_openai_dict_format accepts the same empty content, so such a message round-trips.
• The Hugging Face message converter no longer raises on an assistant message with no content parts, and sends it with empty content instead.

v3.1.0

⭐️ Highlights

🪝CompactionHook and Built-in Compactors for Context Length Management

Experimental context compaction for Agent. Runs before LLM calls and shortens the conversation once it crosses a configured fraction of the context window. The built-in SlidingWindowCompactor first removes entire historical turns, then, if needed, individual steps of the current task, replacing what it removes with a short omission note. A second experimental compaction strategy, ToolResultPruningCompactor, instead of dropping whole turns, replaces older/large tool results with placeholders while keeping the most recent tool-calling steps (and their parallel results) intact.

from haystack.hooks.compaction import CompactionHook, SlidingWindowCompactor, ToolResultPruningCompactor
from haystack.components.generators.chat import OpenAIResponsesChatGenerator
hook = CompactionHook(
compactor=SlidingWindowCompactor(), # or ToolResultPruningCompactor(min_keep_steps=2, min_tokens=200),
context_window=400_000,
compact_at=0.7,
compact_to=0.4,
)
agent = Agent(
chat_generator=OpenAIResponsesChatGenerator(model="gpt-5.4-nano"),
tools=[web_search],
hooks={"before_llm": [hook]},
)

🪙 New Token Counters for Estimating Token Usage

New haystack.token_counters module for estimating message/tool-schema size before sending a request (e.g. to decide when to compact). ApproximateTokenCounter needs no dependencies; TiktokenCounter is a local counter, closer estimates for OpenAI models; OpenAITokenCounter calls OpenAI's counting API for exact, model-specific counts.

from haystack.token_counters import OpenAITokenCounter, ApproximateTokenCounter, TiktokenCounter
from haystack.dataclasses import ChatMessage
</tr></table> 

... (truncated)

Commits

• d60cce0 bump version to 3.1.1
• 0f09023 bump version to 3.1.1-rc1
• 676b3d5 feat: relax OpenAI and HF chat message conversions (#12545)
• 16249e9 test: derive expected OpenAI usage dicts from the streamed model (#12524)
• fa933e1 fix: fix failing test caused by PyPDF 6.16.2 update (#12463)
• 859a6eb bump version to 3.1.0
• 5de8d6c bump version to 3.1.0-rc3
• 46396f4 test: enable mypy typing checks for test/components/routers/ (#12354)
• e37cc94 bump version to 3.1.0-rc2
• 5bf0b09 test: reconcile env-var security test with callable traversal hardening (#12430)
• Additional commits viewable in compare view

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