fix(scope): harden final ownership boundaries

packages/core/system-prompt/README.md

@@ -13,10 +13,10 @@ System prompt assembly registry. Plugins contribute ordered text sections, tool-
 
 ### Public API
 
-- `ctx.systemPrompt.section(section: PromptSection): () => Promise<void> | void` Contribute a section. The registry snapshots `name`, `order`, and the text value/callback, so later caller-object mutation cannot rename a stored section. The layer is the CALLING context's scope: `agent.ctx` contributes to that agent alone, SHADOWING a same-named global section there (the per-agent persona mechanism — a scoped `deployment:persona`). Duplicate names within one layer throw, and a globally protected section name cannot be shadowed. Disposed with the calling fiber.
-- `ctx.systemPrompt.tools(provider: (context: AssembleContext) => ToolProviderResult): () => Promise<void> | void` Contribute tool schemas, evaluated at each assembly with that assembly's context. `ToolProviderResult` = `{ schemas, knownNames? }`: `schemas` is the post-restriction visible set for `context.scope`; `knownNames` (defaulting to the same captured schemas' names) is the pre-restriction universe `toolOrder` validates against. Assembly reads the result, each schema field, and the optional known-name list once before detaching them, rejects non-string schema names/descriptions or known names, and uses those same accepted strings for validation and the model-visible collection. A provider must not return a schema named `TOOL_ORDER_REST`. Scoped providers are consulted only for their scope's assemblies. Disposed with the calling fiber.
-- `ctx.systemPrompt.variable(name: string, provider: (context) => string | undefined): () => Promise<void> | void` Contribute a prompt variable, referenced from section text as `{{name}}`. Scoped variables (via `agent.ctx`) shadow a same-named global for that agent. Duplicate-in-layer or unreferenceable names throw; `undefined` means "no value for this assembly". Disposed with the calling fiber.
-- `ctx.systemPrompt.protect(protection: PromptProtection): () => Promise<void> | void` Make named section/tool contributions authoritative after the assembly waterfall. Protection restores canonical registry/provider presence and definition; restored entries keep canonical order with one another and anchor before their first surviving later unprotected canonical neighbor (or at the end), without undoing listener reordering of unprotected entries. Canonical absence is authoritative too, so a mode-hidden tool cannot be fabricated by a listener. Calling through `agent.ctx` protects only that agent's assemblies. A global section protection additionally reserves its name against scoped shadows; registering either side of that conflict fails loudly instead of treating the shadow as canonical. Each input array is read once and snapshotted, empty protections throw, and disposal removes the protection.
+- `ctx.systemPrompt.section(section: PromptSection): () => Promise<void> | void` Contribute a section. The registry reads `name`, `order`, and the text value/callback once, validates their fixed string/finite-number/string-or-function types, and stores only that accepted record; later caller-object mutation cannot rename or reshape it. The layer is the CALLING context's scope: `agent.ctx` contributes to that agent alone, SHADOWING a same-named global section there (the per-agent persona mechanism — a scoped `deployment:persona`). Duplicate names within one layer throw, and a globally protected section name cannot be shadowed. Disposed with the calling fiber.
+- `ctx.systemPrompt.tools(provider: (context: AssembleContext) => ToolProviderResult): () => Promise<void> | void` Contribute tool schemas, evaluated at each assembly with that assembly's context; a non-function provider rejects before effect storage. `ToolProviderResult` = `{ schemas, knownNames? }`: `schemas` is the post-restriction visible set for `context.scope`; `knownNames` (defaulting to the same captured schemas' names) is the pre-restriction universe `toolOrder` validates against. Assembly reads the result, each schema field, and the optional known-name list once before detaching them, rejects non-string schema names/descriptions or known names, and uses those same accepted strings for validation and the model-visible collection. A provider must not return a schema named `TOOL_ORDER_REST`. Scoped providers are consulted only for their scope's assemblies. Disposed with the calling fiber.
+- `ctx.systemPrompt.variable(name: string, provider: (context) => string | undefined): () => Promise<void> | void` Contribute a prompt variable, referenced from section text as `{{name}}`. The fixed string name and function provider types reject before effect storage. Scoped variables (via `agent.ctx`) shadow a same-named global for that agent. Duplicate-in-layer or unreferenceable names throw; `undefined` means "no value for this assembly". Disposed with the calling fiber.
+- `ctx.systemPrompt.protect(protection: PromptProtection): () => Promise<void> | void` Make named section/tool contributions authoritative after the assembly waterfall. Protection restores canonical registry/provider presence and definition; restored entries keep canonical order with one another and anchor before their first surviving later unprotected canonical neighbor (or at the end), without undoing listener reordering of unprotected entries. Canonical absence is authoritative too, so a mode-hidden tool cannot be fabricated by a listener. Calling through `agent.ctx` protects only that agent's assemblies. A global section protection additionally reserves its name against scoped shadows; registering either side of that conflict fails loudly instead of treating the shadow as canonical. Each optional field and array slot is read once, non-array fields or non-string names reject before effect storage, and the accepted arrays are deduplicated and frozen. Finalization materializes each waterfall-produced entry name once, so a stateful getter cannot evade canonical replacement. Empty protections throw, and disposal removes the protection.
 - `ctx.systemPrompt.assemble(context?: AssembleContext): Promise<PromptAssembly>` Assemble the prompt for one caller: the global layer merged with `context.scope`'s layer (scoped shadows global). Provider output becomes one coherent detached snapshot before `toolOrder` validation. Runs through the scope-filtered `system-prompt/assemble` waterfall, then restores protected contributions from the pre-waterfall canonical assembly. Rejects when a configured `toolOrder` names a tool outside the providers' `knownNames` universe (a restricted-away KNOWN tool is a normal absence), or when a provider returns the reserved rest-entry name.
 
 ### Live events