docs: anchor each subsystem page to its package group; make group READMEs thin tables

core.md read as a type grab-bag: LLM wire vocabulary up front, the agent/loop story buried, and no correspondence to packages/core. It now opens on the packages/core control spine — the package-by-package loop map with a Page column into session/system-prompt/tools/scope — and keeps only what the spine group declares plus the repo-wide patterns: the Agent handle with its delivery/cancellation/interception contracts, the SessionEvent envelope, branded ids, the …Map pattern. The conversation vocabulary (Message/ContentBlock, the model request, adapters — 17 type-equiv blocks) moves to llm-streaming.md, which now declares packages/llm end-to-end; the duplicate ContentBlockMap paste near its seam section folds into the moved section, and the manifest, LINK_MAP, README table rows, website label (Core data structures → Core), and inbound anchors follow.

Every packages/<group>/README pair is now a thin front door in one shape: a why-first intro (bash's seam-pattern-first paragraph rewritten as 'shell execution for the agent'), the package table, and a closing pointer to the owning docs/subsystems page — the bash-style table stays the load-bearing middle. Load-bearing trailing paragraphs relocate rather than vanish: the fs no-timeout rationale becomes a filesystem.md section (both languages), session's four sectioned tables merge into one 12-row table, examples' legacy-bin H2 collapses to a pointer at jsonrpc-demo's README, and design rationale that already lives in an Agent Note or subsystem page is now linked instead of restated. All 40 pair records re-recorded.

packages/llm/README.i18n.yaml

@@ -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 packages/llm/README.md
-README.md: 92d9fbfa2b8c8db4700562009db49229b2189ab3
-README.zh.md: 5c6e7aad1db6511bdb660b86e257652128db131f
+README.md: 077ae600c89cff80cd71830e37bda00707c1d837
+README.zh.md: e2bdad7fd0b33116498b50bfa6527974fa140fc9

packages/llm/README.md

@@ -13,3 +13,5 @@ The LLM seam and its provider adapters. The interface package (`llm`) owns the a
 | [`llm-pi-ai/`](llm-pi-ai/README.md) | Multi-provider pi-ai adapter | registers on `ctx.llm` |
 
 Adapters register provider routes on the seam; retry and token measurement remain separate consumers. The child READMEs own routing, metadata, replay, and provider-wire details; the [LLM architecture decisions](../../.agents/notes/implemented/architecture/2026-06-13-twin-llm-adapters.md) own the rationale.
+
+The subsystem reference — messages and blocks, the model request, the `StreamChunk` protocol, the adapter contract — is [docs/subsystems/llm-streaming.md](../../docs/subsystems/llm-streaming.md) (token measurement: [token-meter.md](../../docs/subsystems/token-meter.md)); see the [twin adapters](../../.agents/notes/implemented/architecture/2026-06-13-twin-llm-adapters.md), [replay token meter](../../.agents/notes/implemented/architecture/2026-07-15-replay-token-meter-service.md), and [routed model context](../../.agents/notes/implemented/architecture/2026-07-20-routed-model-context-and-compaction-policy.md) Agent Notes.

packages/llm/README.zh.md

@@ -13,3 +13,5 @@ LLM（大语言模型）seam 及其提供方适配器。接口包（`llm`）负
 | [`llm-pi-ai/`](llm-pi-ai/README.md) | 多提供方 pi-ai 适配器 | 注册到 `ctx.llm` |
 
 适配器在 seam 上注册提供方路由；重试与 token 测量仍是独立消费方。子 README 负责路由、元数据、回放和提供方协议细节；[LLM 架构决策](../../.agents/notes/implemented/architecture/2026-06-13-twin-llm-adapters.md)负责设计原理。
+
+子系统参考——消息与内容块、模型请求、`StreamChunk` 协议、适配器契约——见 [docs/subsystems/llm-streaming.md](../../docs/subsystems/llm-streaming.md)（token 计量：[token-meter.md](../../docs/subsystems/token-meter.md)）；另见[孪生适配器](../../.agents/notes/implemented/architecture/2026-06-13-twin-llm-adapters.md)、[回放 token 计量](../../.agents/notes/implemented/architecture/2026-07-15-replay-token-meter-service.md)与[按路由模型上下文](../../.agents/notes/implemented/architecture/2026-07-20-routed-model-context-and-compaction-policy.md) Agent Note。