TUI hidden mode folds a turn's assistant steps into one message
TUI 隐藏模式把一个轮次的 assistant 步骤折叠为一条消息
Ctrl+O's hidden phase ([consolidated TUI presentation](../architecture/2026-07-28-consolidated-tui-presentation.md)) drops tool cards so the transcript reads as a conversation, but each model step still rendered its own `Assistant` header. A multi-step turn (text → tools → text) therefore showed several consecutive `Assistant` blocks with nothing between them — the removed tool cards were the only thing that had just
English
Problem
Ctrl+O's hidden phase (consolidated TUI presentation) drops tool cards so the transcript reads as a conversation, but each model step still rendered its own Assistant header. A multi-step turn (text → tools → text) therefore showed several consecutive Assistant blocks with nothing between them — the removed tool cards were the only thing that had justified the repeated headers. Codex-style conversation-only reading wants one assistant message per turn.
Decision
Hidden mode is also a fold rule, applied purely as TUI presentation: per turn, the first step whose rendered content is visible (text, or reasoning while reasoning display is on) owns the turn's single Assistant header; every other step renders as a headerless continuation, and a step with no visible body renders nothing at all — a tool-only step neither consumes the header nor leaves a blank segment. Collapsed and expanded phases keep per-step headers; leaving hidden restores them.
Mechanics: StreamingAssistantComponent carries its StepPosition and a setFoldedContinuation presentation flag; createTuiChat keeps a per-turn list of step components and re-derives the fold on Ctrl+O, on each streamed text/reasoning chunk, on message settle, and on retraction of a failed stream (which may hand the header to the next step). Transcript rebuild clears the map and replays the log, so resume, compaction replacement, resize, and theme swaps converge on the same fold. Step timing footers keep their per-step ownership and are unaffected.
Alternatives considered
- Merge steps into one component — collides with per-step streaming lifecycle, retry retraction, and timing footers; the flag on existing components changes only the header/spacer.
- Fold in the session log or
deriveMessages— mutates durable/model-visible history for a UI reading mode; the log stays step-shaped. - Always fold (all visibility phases) — collapsed/expanded interleave tool cards between steps, where per-step headers delimit which output belongs to which step.
Consequences
Hidden mode now reads as one assistant message per turn; turns stay separated by their headers. The fold is recomputed state, never stored, so no session or persistence format changes. Coverage: TUI unit specs for the Ctrl+O cycle header counts, tool-only first step header handoff, per-turn separation, and live streaming + rebuild convergence; keyless snapshot tool-cards-hidden-folded pins the folded frame.
中文
问题
Ctrl+O 的隐藏阶段（整合的 TUI 展示）去掉工具卡片，让 transcript（文本记录）读作一段对话，但每个模型步骤仍渲染自己的 Assistant 标题。因此一个多步骤轮次（文本 → 工具 → 文本）会显示多个连续、之间空无一物的 Assistant 区块——被移除的工具卡片正是重复标题曾经的唯一理由。Codex 风格的纯对话阅读需要每轮次一条 assistant 消息。
决定
隐藏模式同时也是一条折叠规则，且纯粹作为 TUI 展示实现：在每个轮次内，第一个渲染内容可见（有文本，或在 reasoning 显示开启时有 reasoning）的步骤拥有该轮次唯一的 Assistant 标题；其余步骤渲染为无标题的续段，没有可见正文的步骤则完全不渲染——仅有工具调用的步骤既不占用标题，也不留下空白段。折叠与展开阶段保留每步各自的标题；离开隐藏阶段会恢复它们。
机制：StreamingAssistantComponent 携带自己的 StepPosition 和一个 setFoldedContinuation 展示标志；createTuiChat 维护每轮次的步骤组件列表，并在 Ctrl+O、每个流式 text/reasoning chunk、消息结算，以及失败流被撤回（可能把标题移交给下一个步骤）时重新推导折叠。transcript 重建会清空该映射并重放日志，因此恢复、压缩替换、调整尺寸和主题切换收敛到同一折叠结果。步骤计时页脚保持按步骤归属，不受影响。
考虑过的替代方案
- 把多个步骤合并为一个组件——与按步骤的流式生命周期、重试撤回和计时页脚冲突；在现有组件上加标志只改变标题与前导间距。
- 在会话日志或
deriveMessages中折叠——为一种 UI 阅读模式改变持久 / 模型可见的历史；日志保持按步骤的形状。 - 所有可见性阶段都折叠——折叠 / 展开阶段在步骤之间穿插工具卡片，此时每步的标题用来划分哪段输出属于哪个步骤。
后果
隐藏模式现在每轮次读作一条 assistant 消息；轮次之间仍由各自的标题分隔。折叠是重新计算的状态，从不存储，因此会话与持久化格式没有变化。覆盖：TUI 单元测试覆盖 Ctrl+O 循环的标题计数、仅工具的首步骤标题移交、按轮次分隔，以及实时流式 + 重建收敛；无密钥快照 tool-cards-hidden-folded 固定折叠后的帧。