docs: document package KV cache effects

This commit is contained in:
Tianyi Cui
2026-07-19 17:39:50 +08:00
parent b3c4b732d8
commit bcc920369c
93 changed files with 366 additions and 34 deletions

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@@ -2,5 +2,5 @@
# side as of the last confirmed-consistent state. Both languages carry equal authority;
# after editing either side, bring the other along and re-record with:
# pnpm run verify-translation-pairing --write
adding-a-package.md: 2930cee9ab64b382f6211335ae639bce45629d1d
adding-a-package.zh.md: 10e906c320203c3658c103fc8936540f72697d65
adding-a-package.md: 2e4374caff589199288e67bbca58604231a17966
adding-a-package.zh.md: 35b5b9a0705dd0b752d68093769a65c339f6b4e3

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@@ -16,7 +16,7 @@ packages/<group>/<pkg>/
src/index.ts # service default export or plugin (name/inject/apply/Config)
tests/<x>.spec.ts
README.md # service API, events, extension points, design notes,
# + gated Model Experience context blocks or short sentence
# + gated Model Experience context blocks or short form
# + the gated "Known Limitations and Deferred Work" section
# (or a whitelist entry in scripts/verify-package-readme-limitations.ts)
```
@@ -55,6 +55,8 @@ Keep package-specific service API, config, events, extension points, and design
**Token effect**: Fixed, conditional, retained, replaced, capped, or zero-direct token effect.
**KV Cache effect**: Append-only, prefix-stable, replacing, or independent behavior, including the exact conditions that may invalidate reuse.
#### Verbatim text for this context surface, when needed
```markdown
@@ -66,9 +68,9 @@ Stable system-prompt prose of any length, or another long non-generated literal,
- **Consumer-visible gap** — exact boundary, consequence, or maintainer constraint.
````
Fill Model Experience from the implementation. Use one H3 per direct, conditional, capped, lifetime, or auxiliary-model surface, with the two fields shown above. Quote stable text owned by the package: system-prompt prose goes in a titled H4 plus `markdown` fence, other short literals stay inline with named placeholders, and other long literals use the same nested form. Summarize only data-dependent or provider-owned text. A tool-schema surface links its anchored section in the generated [tool catalog](../tool-catalog.md) and states only deltas absent there. Keep prompt and schema surfaces separate when scoping can hide one without the other. The [prose standard](../../.agents/skills/dsh-prose-standard/SKILL.md) governs completeness and ownership; the verifier enforces the mechanical shape.
Fill Model Experience from the implementation. Use one H3 per direct, conditional, capped, lifetime, or auxiliary-model surface, with the three fields shown above. Quote stable text owned by the package: system-prompt prose goes in a titled H4 plus `markdown` fence, other short literals stay inline with named placeholders, and other long literals use the same nested form. Summarize only data-dependent or provider-owned text. A tool-schema surface links its anchored section in the generated [tool catalog](../tool-catalog.md) and states only deltas absent there. Keep prompt and schema surfaces separate when scoping can hide one without the other. In `KV Cache effect`, distinguish append-only growth, a stable repeated prefix, replacement of earlier request tokens, and an independent model request, then name the package-owned changes that can invalidate reuse. “Does not invalidate” means the package preserves an already-reusable prefix; provider cache availability and eviction remain outside the package contract. The [prose standard](../../.agents/skills/dsh-prose-standard/SKILL.md) governs completeness and ownership; the verifier enforces the mechanical shape.
A package with no context effect or one consumer-owned path uses the audited `None, as ` or `Indirectly, through ` sentence in [`SENTENCE_MODEL_EXPERIENCE`](../../scripts/verify-package-readme-model-experience.ts); a model-agnostic generic package may instead join `NO_MODEL_EXPERIENCE_SECTION`. Do not expand either case into a description of another package's work. The limitations [allowlist](../../scripts/verify-package-readme-limitations.ts) is independent. The [Model Experience RFC](../rfc/implemented/process/2026-07-12-package-model-experience-contract.md) records the rationale.
A package with no context effect or one consumer-owned path uses the audited `None, as ` or `Indirectly, through ` sentence in [`SENTENCE_MODEL_EXPERIENCE`](../../scripts/verify-package-readme-model-experience.ts), followed by a non-empty `**KV Cache effect**` field; a model-agnostic generic package may instead join `NO_MODEL_EXPERIENCE_SECTION`. Do not expand either case into a description of another package's work. The limitations [allowlist](../../scripts/verify-package-readme-limitations.ts) is independent. The [Model Experience RFC](../rfc/implemented/process/2026-07-12-package-model-experience-contract.md) records the rationale.
## 5. Verify

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@@ -16,7 +16,7 @@ packages/<group>/<pkg>/
src/index.ts # service default export or plugin (name/inject/apply/Config)
tests/<x>.spec.ts
README.md # service API, events, extension points, design notes,
# + gated Model Experience context blocks or short sentence
# + gated Model Experience context blocks or short form
# + the gated "Known Limitations and Deferred Work" section
# (or a whitelist entry in scripts/verify-package-readme-limitations.ts)
```
@@ -55,6 +55,8 @@ package.json 不变式(由 `pnpm run constraints` / `scripts/check-workspace-c
**Token effect**: Fixed, conditional, retained, replaced, capped, or zero-direct token effect.
**KV Cache effect**: Append-only, prefix-stable, replacing, or independent behavior, including the exact conditions that may invalidate reuse.
#### Verbatim text for this context surface, when needed
```markdown
@@ -66,9 +68,9 @@ Stable system-prompt prose of any length, or another long non-generated literal,
- **Consumer-visible gap** — exact boundary, consequence, or maintainer constraint.
````
根据实现填写 Model Experience。每个直接、条件、上限、生命周期或辅助模型的 surface 使用一个 H3包含上述个字段。引用包拥有的稳定文本:系统提示词放在带标题的 H4 加 `markdown` 围栏中其他短文本以命名占位符内联其他长文本使用相同的嵌套形式。仅概述数据依赖或提供方拥有的文本。tool-schema surface 链接到生成的[工具目录](../tool-catalog.md)中对应的锚定章节,仅说明该处缺失的差异。当作用域可以隐藏 prompt 或 schema 其中之一而不影响另一个时,将二者分开。[行文标准](../../.agents/skills/dsh-prose-standard/SKILL.md)约束完整性与归属;验证器强制执行机械形状。
根据实现填写 Model Experience。每个直接、条件、上限、生命周期或辅助模型的 surface 使用一个 H3包含上述个字段。引用包拥有的稳定文本:系统提示词放在带标题的 H4 加 `markdown` 围栏中其他短文本以命名占位符内联其他长文本使用相同的嵌套形式。仅概述数据依赖或提供方拥有的文本。tool-schema surface 链接到生成的[工具目录](../tool-catalog.md)中对应的锚定章节,仅说明该处缺失的差异。当作用域可以隐藏 prompt 或 schema 其中之一而不影响另一个时,将二者分开。填写 `KV Cache effect` 时,应区分仅追加增长、稳定重复的前缀、替换既有请求 token 和独立模型请求,并列出会使缓存复用失效、且由本包拥有的变化。“不使缓存失效”仅表示本包保留了已有的可复用前缀;缓存是否可用以及何时淘汰不属于本包契约。[行文标准](../../.agents/skills/dsh-prose-standard/SKILL.md)约束完整性与归属;验证器强制执行机械形状。
没有上下文效果或仅有消费方拥有路径的包使用 [`SENTENCE_MODEL_EXPERIENCE`](../../scripts/verify-package-readme-model-experience.ts) 中经过审计的 `None, as ` 或 `Indirectly, through ` 语句;与模型无关的通用包可以改为加入 `NO_MODEL_EXPERIENCE_SECTION`。两种情况都不要展开为对另一个包工作的描述。limitations [allowlist](../../scripts/verify-package-readme-limitations.ts) 独立管理。[Model Experience RFC](../rfc/implemented/process/2026-07-12-package-model-experience-contract.md) 记录了设计动机。
没有上下文效果或仅有消费方拥有路径的包使用 [`SENTENCE_MODEL_EXPERIENCE`](../../scripts/verify-package-readme-model-experience.ts) 中经过审计的 `None, as ` 或 `Indirectly, through ` 语句,随后添加非空的 `**KV Cache effect**` 字段;与模型无关的通用包可以改为加入 `NO_MODEL_EXPERIENCE_SECTION`。两种情况都不要展开为对另一个包工作的描述。limitations [allowlist](../../scripts/verify-package-readme-limitations.ts) 独立管理。[Model Experience RFC](../rfc/implemented/process/2026-07-12-package-model-experience-contract.md) 记录了设计动机。
## 5. 验证

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@@ -4,28 +4,28 @@ Status: implemented
## Problem
A package README can explain APIs and runtime mechanics without answering the question that dominates an agent harness's behavior and cost: what from this package reaches a model request, under which conditions, and how long those tokens remain. The omission is especially hard to audit in a plugin architecture. A consumer may turn a backend result into a tool message, a policy plugin may replace success with an error, compaction may remove old history, and an agent-scoped registration may change one agent's prompt or schemas while leaving every other agent unchanged. Reading only the nominally model-facing packages therefore misses real context effects, while reading source across every dependency is too expensive for routine review.
A package README can explain APIs and runtime mechanics without answering the questions that dominate an agent harness's behavior and cost: what from this package reaches a model request, under which conditions, how long those tokens remain, and whether later requests preserve a reusable KV-cache prefix. The omission is especially hard to audit in a plugin architecture. A consumer may turn a backend result into a tool message, a policy plugin may replace success with an error, compaction may remove old history, and an agent-scoped registration may change one agent's prompt or schemas while leaving every other agent unchanged. Reading only the nominally model-facing packages therefore misses real context effects, while reading source across every dependency is too expensive for routine review.
## Decision
Every workspace package README with a model-facing or model-adjacent contract ends with the canonical [Model Experience section](../../../cookbook/adding-a-package.md#4-write-the-package-readme), immediately before `## Known Limitations and Deferred Work`; a package on the no-limitations allowlist ends with Model Experience itself. An audited model-agnostic generic package omits the section through `NO_MODEL_EXPERIENCE_SECTION`.
Packages with direct, conditional, capped, lifetime, multi-surface, or auxiliary-model effects use one H3 per context surface. Each names what the relevant model receives and when, then classifies the token effect. Stable package-owned text is quoted exactly: system-prompt prose and other long literals use a nested H4 plus `markdown` fence, while short literals stay inline with named interpolation placeholders. Tool-schema surfaces link their anchored section in the generated [tool catalog](../../../tool-catalog.md) and state only composition or configuration deltas; runtime-only definitions explain why the catalog omits them. Data-dependent and provider-owned text is summarized. Agent-scoped visibility is explicit, and prompt and schema surfaces remain separate when scoping can hide one without the other.
Packages with direct, conditional, capped, lifetime, multi-surface, or auxiliary-model effects use one H3 per context surface. Each names what the relevant model receives and when, classifies the token effect, and states the KV-cache effect. The cache field distinguishes append-only growth, a stable repeated prefix, replacement of earlier tokens, and an independent model request; it names every package-owned configuration, scope, lifecycle, compaction, or routing change that can alter the request before newly appended content. “Does not invalidate” means the package preserves an already-reusable prefix, not that a provider promises a cache hit or retention period. Stable package-owned text is quoted exactly: system-prompt prose and other long literals use a nested H4 plus `markdown` fence, while short literals stay inline with named interpolation placeholders. Tool-schema surfaces link their anchored section in the generated [tool catalog](../../../tool-catalog.md) and state only composition or configuration deltas; runtime-only definitions explain why the catalog omits them. Data-dependent and provider-owned text is summarized. Agent-scoped visibility is explicit, and prompt and schema surfaces remain separate when scoping can hide one without the other.
A package with no model-context effect, or one path rendered entirely by another package, uses the verifier's audited one-sentence form: `None, as ` or `Indirectly, through `. Pure transport and keyless test-support packages use the none form when they create no model-bound content. Provider backends use the indirect form even when they cap or filter data, and wiring bundles use it when named children own every effect. These sentences locate the contribution without restating the consumer. Structured sections likewise document only package-owned inputs, transformations, and deltas.
A package with no model-context effect, or one path rendered entirely by another package, uses the verifier's audited short form: one sentence beginning `None, as ` or `Indirectly, through ` followed by a `**KV Cache effect**` field. Pure transport and keyless test-support packages use the none form when they create no model-bound content. Provider backends use the indirect form even when they cap or filter data, and wiring bundles use it when named children own every effect. These sections locate the contribution and disclaim direct cache invalidation without restating the consumer. Structured sections likewise document only package-owned inputs, transformations, and deltas.
`verify-package-readme-model-experience` discovers package manifests and validates the three classifications, canonical final-section order, required fields, concrete literal evidence, nested verbatim blocks, and anchored tool-catalog links. It runs in `doc-sync` and the parallel gate runner. Review still owns coverage, link relevance, and factual accuracy.
`verify-package-readme-model-experience` discovers package manifests and validates the three classifications, canonical final-section order, required model-view, token, and KV-cache fields, concrete literal evidence, nested verbatim blocks, and anchored tool-catalog links. It runs in `doc-sync` and the parallel gate runner. Review still owns coverage, link relevance, and factual accuracy.
## Alternatives considered
- **Document only packages that register prompts or tools** — rejected because backends, policy plugins, adapters, persistence, scoping, and compaction change the content or lifetime of tokens without owning a model-facing schema.
- **Generate one central context-cost catalog from source** — rejected because an AST can find registrations but cannot infer semantic conditions such as history retention, output truncation, parent-versus-child visibility, or an auxiliary model boundary. The package README is the implementation-local contract; a central copy would add another drift surface.
- **Require numeric token counts** — rejected because exact counts depend on the selected model tokenizer, adapter serialization, configuration, and runtime data. The stable contract is the growth shape: fixed per request, conditional per call, retained, replaced, capped, or zero-direct.
- **Use a three-column table** — rejected because exact source text and conditional result shapes make cells dense and difficult to scan. Repeated subsections give each context surface readable vertical space while preserving the same fields.
- **Use a table** — rejected because exact source text and conditional result shapes make cells dense and difficult to scan. Repeated subsections give each context surface readable vertical space while preserving the same fields.
- **Allow every zero-impact package to omit the section** — rejected because unconstrained absence is ambiguous between an audited zero and forgotten documentation. Omission is reserved for model-agnostic generic packages named with a reason in the verifier; model-adjacent zero-impact packages keep one explicit sentence.
- **Require the full structured form for audited zero or simple indirect packages** — rejected because it repeats labels around one fact. A gated sentence preserves explicit coverage without the ceremony.
- **Require the full structured form for audited zero or simple indirect packages** — rejected because it repeats labels around one fact. A gated sentence plus cache field preserves explicit coverage without the ceremony.
- **Convention without a gate** — rejected because a repo-wide contract must also cover every future package; review memory cannot reliably detect an omitted README section.
## Consequences
A reviewer can start at any model-facing or model-adjacent package and see its contribution to the conversation model, child models, and auxiliary calls without reconstructing the full plugin graph. Token-budget work can distinguish repeated request overhead from data-dependent history, and agent-scoped changes have an explicit documentation checkpoint. Package authors maintain one or more compact context-surface blocks or one classified sentence whenever model-visible behavior changes; audited generic packages carry no irrelevant model boilerplate. The structured fields do not promise provider-exact token counts; measurements remain model- and workload-specific, while the documented growth and visibility contract stays stable.
A reviewer can start at any model-facing or model-adjacent package and see its contribution to the conversation model, child models, and auxiliary calls without reconstructing the full plugin graph. Token-budget work can distinguish repeated request overhead from data-dependent history, while cache-sensitive work can identify append-only paths and the earliest package-owned prefix mutation. Agent-scoped changes have an explicit documentation checkpoint. Package authors maintain one or more compact context-surface blocks or one classified short form whenever model-visible behavior changes; audited generic packages carry no irrelevant model boilerplate. The structured fields do not promise provider-exact token counts or cache hits; measurements remain model-, provider-, and workload-specific, while the documented growth, visibility, and prefix-stability contract stays stable.