docs(AGENTS): rewrite the root standing orders to the 1,500-word budget

Applies the documentation standard to its biggest offender. Every rule
survives as one to three lines plus a link to its durable home; the
stories, duplicate statements, and re-narrations go:

- Situational clusters evict to new homes: docs/testing.md (tiers,
  with-key policy, real-over-mock, world-verification, real-entry-path
  guards), docs/defensive-patterns.md (the bug-class rules), and
  docs/cookbook/responding-to-pr-review-on-a-stack.md (the stacked-PR
  review procedure).
- Doc-authoring rules consolidate into docs/AGENTS.md § Writing rules
  (current-state-never-history, md-wrap, ts-block compilation, @mode,
  catalog same-change, pair same-change).
- packages/README.md drops to the group table + the extension-vs-bundle
  dependency rule; the hand ASCII graph yields to the generated
  module-graph.md; group READMEs are the canonical per-package map.
- packages/AGENTS.md keeps only its packages-specific rules (export
  shape, ctx.get, real-Loader coverage); examples/AGENTS.md repoints
  its with-key-policy link; rfc/README.md loses a narrated-history
  aside; dsh-code-review / dsh-find-simplifications / verify-md-wrap
  references follow the moved content.
- Budget manifest ratchets: AGENTS.md 8200 -> 1500 (now 1,495 words),
  packages/README.md 1900 -> 600, packages/AGENTS.md 600 -> 450; the
  two new eviction docs join the budget set (testing 800, defensive
  550); docs/AGENTS.md raises 1000 -> 1250 for the absorbed writing
  rules (the one justified increase). The doc-tiers RFC's deferred list
  prunes the two items this change ships.

packages/AGENTS.md

@@ -1,18 +1,16 @@
 # AGENTS.md — Harness Packages
 
-This directory contains all `@deepseek-ai/dsh-*` harness packages. When editing code here, follow these conventions:
+This directory contains all `@deepseek-ai/dsh-*` harness packages. Repo-wide conventions (effects, declaration merging, waterfall semantics, ESM, testing policy) are in the root [AGENTS.md](../AGENTS.md) § Conventions; the points below are packages-specific.
 
-- **Effect-based registrations**: every contribution (tool, section, adapter, agent, event listener) goes through `ctx.effect()` / `ctx.on()`, and `register()` methods return disposers. Never use bare arrays or manual cleanup.
-- **Declaration merging**: services declare their ctx key in `declare module 'cordis' { interface Context { } }` and their events in `interface Events`. Merge-extensible maps (`ContentBlockMap`, `MessageSourceMap`, `FinishReasonMap`, `TurnTriggerMap`, `TurnEndReasonMap`, `SessionEventMap`) are how plugins add new variants.
-- **Waterfall semantics**: `ctx.waterfall` listeners receive `(...args, next)`; call `next()` to delegate, or return without it to short-circuit (veto). Never call `next()` after returning.
 - **Plugin export shape — namespace OR default, never both.** A *service* package exports the service class as `export default` (the Loader instantiates it). A *function/namespace* plugin exports `name` / `inject` / `Config` / `apply` as separate named exports and **must NOT add `export default`** — the cordis Loader's `unwrapExports` does `exports.default ?? exports`, so a stray default export collapses the module to the bare `apply` function and silently discards the `inject`/`name`/`Config` namespace, leaving the plugin with no injected services (it then throws `cannot get property … without inject` at load). See [docs/postmortem/0001](../docs/postmortem/0001-acp-default-export-drops-inject.md).
 - **Read an optional (non-injected) service via `ctx.get(name)`, not `ctx.<name>`.** For a service a plugin reads opportunistically but deliberately leaves out of `static inject` (e.g. `AgentLoop` reading `sessionPersistence`), the `ctx.<name>` property proxy resolves by an ancestor-only fiber walk that throws when the call arrives through a foreign traceable shadow (the service lives on a sibling fiber). `ctx.get(name)` is the topology-independent global-store lookup, strict by default (an inactive/absent backend reads as `undefined` — prefer it over the `ctx.get(name, false)` overload, which also skips the active-state check). Services that ARE in `static inject` resolve fine via `ctx.<name>`. See [docs/postmortem/0001](../docs/postmortem/0001-acp-default-export-drops-inject.md).
-- **Tests**: vitest in `packages/<group>/<pkg>/tests/*.spec.ts`. Every registry needs an HMR-safety test (register a plugin, dispose its fiber, assert cleanup). Err on the side of more tests — edge cases, error paths, event ordering, races. A plugin shipped via `cordis.yml` also needs at least one test that drives it through the REAL Loader/export path (hand-built `ctx.plugin({...})` mounts bypass `unwrapExports` and cannot catch a broken export shape) — see AGENTS.md § Defensive patterns "Line coverage is not behavior coverage". Real-API (with-key) e2e tests are cheap here (we are DeepSeek) and welcome — write many, especially smoke tests; see AGENTS.md § Secrets / .env.
+- **A plugin shipped via `cordis.yml` needs at least one test through the REAL Loader/export path** — hand-built `ctx.plugin({...})` mounts bypass `unwrapExports` and cannot catch a broken export shape. Full testing policy (tiers, with-key generosity, real-entry-path guards): [docs/testing.md](../docs/testing.md).
 
 Naming notes:
-- A *service* `src/index.ts` exports the service class as `export default` + all public types; a *function/namespace plugin* `src/index.ts` exports `name`/`inject`/`Config`/`apply` as named exports and NO default (see the plugin-export-shape rule above)
-- `src/types.ts` contain only types — no runtime code
-- Tests live at package level under `tests/`, not `src/__tests__/`
-- A package's README and module/JSDoc comments are part of the change: when you alter behavior (config keys, defaults, error codes, wire fields), update them in the same commit. CI runs `pnpm run doc-sync`, which typechecks fenced `ts` blocks in `packages/*/*.md` and `packages/*/*/*.md`, regenerates the cordis events/services catalog from the `interface Events` / `interface Context` declarations (failing if the committed copy is stale), and checks markdown wrapping across this file too — but it does NOT catch prose drift (config keys, defaults, error codes), so those stay on the author. A new event needs an `@mode` tag on its JSDoc (the catalog generator hard-errors without it — see the root AGENTS.md).
+
+- A *service* `src/index.ts` exports the service class as `export default` + all public types; a *function/namespace plugin* `src/index.ts` exports `name`/`inject`/`Config`/`apply` as named exports and NO default (the export-shape rule above).
+- `src/types.ts` contains only types — no runtime code.
+- Tests live at package level under `tests/`, not `src/__tests__/`.
+- A package's README and JSDoc are part of the change: altered behavior (config keys, defaults, error codes, wire fields) updates them in the same commit. `doc-sync` gates what it can; prose accuracy stays on the author ([the documentation standard](../docs/AGENTS.md)).
 
 Read the per-package README.md for package-specific details: service API, events, extension points, TODOs.