Recorded user-source attribution compatibility
已记录的 user-source 归属兼容性
A producer-owned message source appears transitively in several persisted event types. A new attribution kind changes their union fingerprints even when existing readers preserve its fields without the producer. Request-only prompts need no durable identity, but constructing them as Session messages adds unnecessary source alternatives to that union.
Source compatibility: Chinese title uses a compatible non-canonical header
English
Problem
A producer-owned message source appears transitively in several persisted event types. A new attribution kind changes their union fingerprints even when existing readers preserve its fields without the producer. Request-only prompts need no durable identity, but constructing them as Session messages adds unnecessary source alternatives to that union.
Decision
The core-owned user-message source property binds the recorded compatibility policy. A producer separately qualifies its literal wire kind as attribution-only. Both saved schemas must carry compatible policy state before a qualified addition receives a same-version classification. Existing alternatives remain structurally compared; missing policy, unqualified additions, removals, and changes to existing semantic groups retain strict classification. Fixed system, model, and tool source fields do not participate.
The tmux-context producer qualifies its location attribution. Its own projection uses the kind to avoid repeated injection, while readers without that producer retain the recorded content and every source JSON property. The qualification promises reader independence; it does not forbid producer-local duplicate suppression.
RequestMessage accepts a durable Message or a user-only RequestUserInput with content and no id or source. The LLM service and provider serializers accept both; Session writes, Agent delivery, and persisted title-request inputs require durable messages. Auto Review's outer prompt and the compaction summarizer's final instruction use request-only inputs and retain their content and freezing. The caller receives no implicit durable conversion. Assistant replay metadata and tool-result correlation retain their existing requirements.
The finalized V4 acknowledgement records the user-source policy and removes the two request-only source registrations. Its original predecessors and header transition remain intact. This does not grant a general exception for removing accepted variants: the producer-source migration preserves its producer mappings and extension namespaces, including historical request-only kinds, independently of active source declarations. Catalog generation and comparison remain owned by the persistence reference.
Alternatives considered
Treat every source addition as breaking. This would require a Session-format increment for attribution that readers already retain safely, without distinguishing it from semantic changes.
Relax every discriminated union or infer compatibility from current names. A generic exception would admit semantic variants. Current declarations cannot establish what an older snapshot promised, and structural equality does not establish ownership of a source property.
Use durable messages for every request. Detached prompts would retain manufactured identities and unnecessary source declarations. The explicit user-only alternative permits their removal while typed Session interfaces retain durable identity requirements.
Narrow historical context forms to current writer examples. Writer examples do not establish every value admitted by released readers. Those read-facing variants remain represented.
Consequences
A qualified addition still changes affected event fingerprints and requires an acknowledgement. Reviewers must verify the producer's attribution promise; type analysis cannot establish replay semantics or detect behavior hidden in opaque values.
Codec-to-Session tests retain unknown user attribution and extra JSON fields without the producer. Provider equality tests compare request-only and durable inputs, while type assertions reject request-only inputs at durable writes. Recorded Session generations and the V3-to-V4 conversion remain independent of catalog policy and rendering.
中文
问题
生产者拥有的消息 source 会传递性地出现在多个持久化事件类型中。即使已有读取方无需该生产者也能保留字段，新增归属 kind 仍会改变这些联合类型的指纹。仅供请求使用的提示不需要持久身份，但将其构造成 Session 消息会为联合类型增加不必要的 source 分支。
决策
核心拥有的 user-message source 属性绑定已记录的兼容性策略。生产者另行将其 wire 字面量 kind 声明为仅用于归属。双方保存的 schema 必须具有兼容的策略状态，符合条件的添加才能获得同版本分类。已有分支继续接受结构比较；缺失策略、未标记的添加、删除以及已有语义分组的变更继续采用严格分类。固定的 system、model 和 tool source 字段不参与。
tmux-context 生产者将位置归属标记为符合条件。其自身投影使用 kind 避免重复注入，而未安装该生产者的读取方保留已记录内容及 source 的每个 JSON 属性。该标记承诺读取方不依赖生产者，并不禁止生产者内部的去重。
RequestMessage 接受持久化 Message，或仅含 content、没有 id 和 source 的 user 专用 RequestUserInput。LLM 服务和 provider 序列化器接受两者；Session 写入、Agent 交付及持久化标题请求输入要求持久化消息。Auto Review 的外层提示和压缩摘要器的最终指令使用仅供请求使用的输入，并保留内容与冻结行为。调用方不会获得隐式持久化转换。Assistant 回放元数据和工具结果关联保持原有要求。
已定稿的 V4 确认记录保存 user-source 策略，并移除两个仅供请求使用的 source 注册。原有前驱和 header 迁移保持不变。这不构成删除已接受分支的通用例外：producer-source 迁移独立于活动 source 声明保留生产者映射与扩展命名空间，包括历史的仅供请求使用的 kind。目录生成和比较仍由持久化参考负责。
考虑过的替代方案
将所有 source 添加视为破坏性变更。 这会要求为读取方已能安全保留的归属信息提升 Session 格式版本，无法区分它与语义变更。
放宽所有可辨识联合或从当前名称推断兼容性。 通用例外会接纳语义分支。当前声明不能确定旧快照作出的承诺，结构相等也不能确定 source 属性的归属。
为每个请求使用持久化消息。 独立提示会保留人为制造的身份和不必要的 source 声明。显式的 user 专用分支允许移除它们，同时让带类型的 Session 接口继续要求持久身份。
将历史 context 形式收窄到当前写入方示例。 写入方示例不能确定已发布读取方接纳的全部值。这些面向读取的分支继续保留。
影响
符合条件的添加仍会改变相关事件指纹，并要求确认记录。Review 者必须验证生产者的归属承诺；类型分析不能确定回放语义，也不能发现不透明值中隐藏的行为。
Codec 到 Session 的测试在未安装生产者时保留未知 user 归属和额外 JSON 字段。Provider 等价测试比较仅供请求使用的输入与持久化输入，类型断言则拒绝在持久化写入处使用仅供请求使用的输入。已记录的 Session 世代及 V3→V4 转换不依赖目录策略和渲染。