fix(scope): harden final ownership boundaries

docs/core-data-structures/core.md

@@ -16,8 +16,10 @@ Everything else is documented on a **sub-page**, not here. The rule that draws t
 | Sub-page | Owns |
 |---|---|
 | [llm-streaming.md](llm-streaming.md) | the `StreamChunk` wire protocol + adapter contract, `BlockAssembler`, the `LlmAdapter` seam |
+| [scope.md](scope.md) | scoped registration identity, dispatch carriers, and the owned `Scope` context |
 | [session.md](session.md) | the full `SessionEventMap` variant catalog, `TurnTrigger`/`TurnEndReason`, `deriveMessages()`, the turn-enclosure invariant |
 | [persistence.md](persistence.md) | the durability seam: `SessionPersistence`, JSONL + SQLite backends, `session/flush`, crash recovery, `SessionHeader` |
+| [system-prompt.md](system-prompt.md) | per-assembly context, tool-provider results, and canonical contribution protection |
 | [tools.md](tools.md) | `ToolDefinition` full fields, the schema DSL, `ToolExecution`/`ToolResult`, tool-presentation UI types, and the guarded execution pipeline |
 | [user-interaction.md](user-interaction.md) | the UI-backed human question/answer seam: `AskUserQuestionRequest`, answer/options vocabulary, provider API, error taxonomy |
 | [approval.md](approval.md) | the one-shot user-approval seam: `ApprovalRequest`, `ApprovalOutcome`, per-session policy, audit and answerer contracts |

docs/core-data-structures/scope.md

@@ -0,0 +1,31 @@
+# Scoped Registration
+
+The [scope package](../../packages/core/scope) supplies the identity and carrier vocabulary that makes one registration context mean both per-agent visibility and shared lifetime ownership. It is a library primitive rather than a Cordis service; the [agent-scope RFC](../rfc/implemented/architecture/2026-07-08-agent-scope-contexts.md) owns the design rationale, while the package [README](../../packages/core/scope/README.md) owns the callable API and filtering semantics.
+
+Source: [`packages/core/scope/src/index.ts`](../../packages/core/scope/src/index.ts).
+
+## Identity and dispatch carrier
+
+`ScopeKey` is an opaque object identity. The shipped loop uses the live `Agent` object as its own key, but the primitive never inspects the object.
+
+```ts type-equiv
+type ScopeKey = object
+```
+
+`Scoped<T>` is the compile-time brand on the proxy returned by `scopeTarget(base, key)`. Scope-filtered event declarations require this carrier as their `this` type, preventing an ordinary subject object from type-checking as the dispatch carrier.
+
+```ts type-equiv
+type Scoped<T> = T & { readonly [ScopedBrand]: 'dsh.scope.carrier' }
+```
+
+## Owned registration context
+
+`Scope` pairs the tagged registration context with two teardown surfaces. `rawDispose` preserves the exact Cordis disposer identity needed by an ordered composite effect; `dispose()` is the public shared quiescence boundary for direct and racing callers.
+
+```ts type-equiv
+interface Scope {
+  ctx: Context
+  rawDispose: () => Promise<void> | void
+  dispose(): Promise<void>
+}
+```

docs/core-data-structures/system-prompt.md

@@ -0,0 +1,37 @@
+# System Prompt Assembly
+
+The [system-prompt package](../../packages/core/system-prompt) owns the data exchanged between prompt contributors and one assembly call. The package [README](../../packages/core/system-prompt/README.md) documents registration, ordering, scoping, and rendering behavior; this page pins the literal cross-package shapes that plugins implement or pass.
+
+Source: [`packages/core/system-prompt/src/index.ts`](../../packages/core/system-prompt/src/index.ts).
+
+## Assembly context
+
+`AssembleContext` identifies the scope layer one assembly resolves. It is merge-extensible: `dsh-agent` adds the optional live `agent` field, and `assembleContextFor(agent)` sets that field and `scope` together.
+
+```ts type-equiv
+interface AssembleContext {
+  scope?: ScopeKey
+}
+```
+
+## Tool-provider result
+
+`ToolProviderResult.schemas` is the model-visible set for the current assembly. `knownNames` is the provider's pre-restriction name universe used to distinguish a configured-name typo from a known tool that is deliberately hidden in this scope.
+
+```ts type-equiv
+interface ToolProviderResult {
+  schemas: ToolSchema[]
+  knownNames?: readonly string[]
+}
+```
+
+## Canonical contribution protection
+
+`PromptProtection` names section and tool contributions whose canonical registry output remains authoritative after the assembly waterfall. Either field may be omitted, but a registration with no names is rejected.
+
+```ts type-equiv
+interface PromptProtection {
+  sections?: readonly string[]
+  tools?: readonly string[]
+}
+```