docs: tighten prose audit after master retarget

docs/rfc/implemented/architecture/2026-06-24-web-capability-seam.md

@@ -22,7 +22,7 @@ Web access is a first-class capability seam following [the capability-seam RFC](
 
 Providers do not register tools. Providers register capabilities. `dsh-tool-web` is the only owner of model-facing names, descriptions, prompt guidance, JSON schemas, and presentation.
 
-Search and fetch are separate capabilities and separate model-facing tools, but they are deliberately one seam. `ctx.web` is a single web-access middle layer between provider packages on one side and the tool consumer on the other: one service to inject, one provider-selection policy owner, one abort/error vocabulary, one place a product configures "how this harness reaches the web." The two halves do not share a request schema and have no shared business logic — search normalizes provider-backed discovery into a portable result with optional answer text and citeable sources, while fetch retrieves a concrete public HTTP(S) URL and returns a status code plus bounded decoded content — but they are parallel registries on one capability surface, not two surfaces. The cost is a `WebService` whose registry/exec methods come in `Search`/`Fetch` pairs; that parallelism is intentional, not a missed extraction. Splitting into `dsh-search` and `dsh-fetch` is the rejected alternative below.
+Search and fetch are separate tools but one web-access seam. `ctx.web` owns provider selection, abort/error vocabulary, and deployment configuration for both parallel registries. Their request schemas and provider logic remain separate; the shared service is the product boundary for reaching the web.
 
 `dsh-tool-web` registers model-facing web tools when the product has enabled those tools and the `ctx.web` seam is present. Backend availability is an execution-time concern, not a schema-registration concern:
 
@@ -66,7 +66,7 @@ flowchart LR
 
 `@deepseek-ai/dsh-web` depends only on Cordis and low-level harness support. It declares `ctx.web`, provider interfaces, request/result types, the provider status type, and error codes. It does not import tool, agent, session, LLM, or provider packages.
 
-Provider packages depend on `@deepseek-ai/dsh-web` and Cordis. They own credentials, endpoint config, provider-specific request mapping, provider-specific response parsing, and provider-specific error translation into `WebError`. They issue network requests with platform-native `fetch` at the repo's Node floor, mirroring `@deepseek-ai/dsh-llm-deepseek`'s adapter, NOT a cordis HTTP-client service (`ctx.http`/`@cordisjs/plugin-http`) — even where a Perplexity provider's request is shaped like an OpenAI-compatible chat completion, that wire shape is a provider-private detail and does not make the provider depend on `ctx.llm`. A provider does NOT own the `ctx.web` key (two search providers cannot both own it): like `dsh-llm-deepseek`, each provider package is a function/namespace plugin (`inject: ['web']`) whose `apply` constructs the backend and calls `ctx.web.registerSearchProvider` / `registerFetchProvider`. `@deepseek-ai/dsh-web` is the `export default` service that owns the key.
+Provider packages depend only on `dsh-web` and Cordis. They own credentials, endpoints, wire mapping, parsing, and `WebError` translation, using platform `fetch`. Each provider injects the shared service and registers a backend; only `dsh-web` owns the `ctx.web` key. Provider-private protocol shapes do not create dependencies on `ctx.llm` or a Cordis HTTP service.
 
 `@deepseek-ai/dsh-tool-web` depends on `@deepseek-ai/dsh-web`, `@deepseek-ai/dsh-tools`, `@deepseek-ai/dsh-system-prompt`, and Cordis. It never imports concrete provider packages.
 
@@ -239,7 +239,7 @@ type WebFetchBody =
 
 `WebFetchResult.url` is the final URL after allowed redirects. The request URL is already present in `WebFetchRequest`, so there is no separate `requestedUrl`/`finalUrl` pair.
 
-`WebFetchBody` is a CLOSED discriminated union owned by `dsh-web`, not a merge-extensible map. The merge-extensible pattern (`ContentBlockMap`) exists for variants that independent plugins introduce and the seam cannot foresee; body kinds are not that — `dsh-web` declares the kind, the fetch provider decodes it, and `dsh-tool-web` renders it, so a new kind is a coordinated change across three known packages, not a plugin extension. Keeping it closed buys compile-time exhaustiveness: consumers `switch` on `kind` ending in `default: assertNever(body, …)`, so adding a kind breaks compilation at every consumer that must render it (e.g. `tool-web`'s `html`→markdown vs `text` passthrough) until that arm is written. Each arm stays its own object literal even when the fields coincide today, leaving room for arm-specific fields (a future `pdf` body's `pageCount`, a `json` body's parsed value) without reshaping the type. Since the harness is unreleased, extending this closed union later is free (no migration, no compat shim).
+`WebFetchBody` is a closed discriminated union because body kinds require coordinated changes to the seam, provider, and tool rather than independent plugin extension. Exhaustive switches make a new kind fail compilation at every renderer until handled. Separate object arms leave room for kind-specific fields.
 
 The provider owns safe resource retrieval: URL validation, HTTP transport, redirect policy, timeout, abort propagation, byte caps, charset decoding, content-type classification, and binary rejection. `dsh-tool-web` owns presentation: HTML-to-markdown, HTML-to-text, truncation formatting for the model, and future summaries.