yoi/work-items/open/20260603-001124-unify-reasoning-block-lifecycle/item.md

id	slug	title	status	kind	priority	labels	created_at	updated_at	assignee	legacy_ticket
20260603-001124-unify-reasoning-block-lifecycle	unify-reasoning-block-lifecycle	Unify reasoning persistence with block lifecycle	open	task	P2	llm-worker reasoning timeline	2026-06-03T00:11:24Z	2026-06-03T00:51:09Z	null	null

Background

Yoi currently has two reasoning-related event paths in llm-worker:

• streaming thinking/reasoning content is represented as block lifecycle events (BlockStart / BlockDelta / BlockStop);
• finalized reasoning persistence is represented separately as ReasoningItemEvent / ReasoningItemCollector and later converted into Item::Reasoning.

This duplicates the same conceptual model. Thinking and reasoning are provider vocabulary for the same class of generated model content, and generated content should be represented through the block lifecycle. ReasoningItem exists because the current reasoning block stop event does not carry the provider material needed for persistence, not because it is a distinct domain concept.

Backward compatibility is not required for this cleanup. Prefer a clear event model over compatibility aliases or parallel old/new APIs.

Requirements

• Make the block lifecycle the authoritative path for reasoning/thinking generation and persistence.
• Remove the separate finalized reasoning side channel:
  • ReasoningItemEvent;
  • ReasoningItemKind;
  • ReasoningItemCollector;
  • Timeline::on_reasoning_item / dispatch_reasoning_item and related handler storage.
• Extend the reasoning/thinking block representation so block completion can carry all provider material required to build Item::Reasoning, including where applicable:
  • reasoning item id;
  • text;
  • summary;
  • encrypted content;
  • Anthropic thinking signature;
  • redacted thinking payload metadata.
• Update Anthropic streaming conversion so thinking_delta / signature_delta are accumulated in the block lifecycle and finalized through reasoning block stop metadata, without emitting a separate ReasoningItem event.
• Update OpenAI Responses conversion so completed reasoning items are represented as reasoning block lifecycle events, including metadata-only reasoning where there is no text delta.
• Update Worker collection/finalization so Item::Reasoning is built from reasoning block lifecycle state rather than ReasoningItemCollector.
• Preserve live streaming thinking/reasoning callbacks for UI/trace consumers.
• Preserve persisted reasoning history round-trip behavior for Anthropic and OpenAI Responses.
• Remove or rename misleading comments that imply reasoning is a meta/single event rather than generated content.
• Do not add backward-compatible aliases or keep the old ReasoningItem event path.

Non-goals

• Do not redesign provider request serialization beyond what is needed to preserve existing reasoning round-trip behavior.
• Do not add a new E2E spawned-process test framework.
• Do not change public product behavior except for the internal event model cleanup.
• Do not hide missing provider material by dropping signatures, summaries, ids, or encrypted content.

Acceptance criteria

• ReasoningItemEvent / ReasoningItemCollector and their Timeline handler path are removed.
• Anthropic thinking stream still produces live reasoning/thinking block callbacks and persists Item::Reasoning with signature/redacted material intact.
• OpenAI Responses reasoning items still persist and round-trip id, summary, and encrypted_content as before.
• Existing reasoning persistence tests are updated to assert the block-lifecycle path rather than the removed side channel.
• No compatibility aliases or duplicate reasoning concepts remain unless justified in the implementation report.
• Validation includes focused llm-worker reasoning tests, cargo test -p llm-worker --lib, cargo check --workspace --all-targets, ./tickets.sh doctor, git diff --check, and nix build .#yoi unless explicitly deferred with rationale.