feat(chat)!: remove provideChat(), fix app-level markdown registry overrides, and three API cleanups (#1055)

* feat(chat)!: remove provideChat(), ChatConfig, and CHAT_CONFIG

No component in @threadplane/chat ever injected CHAT_CONFIG, so
provideChat({}) configured nothing: renderRegistry, avatarLabel, and
assistantName were values only a consumer's own wrappers could read back.
The provider, the token, the interface, and the dead ChatConfig duplicate
in chat.types.ts are deleted outright.

Every call site follows: 35 cockpit example app.config.ts files, both
standalone example apps, the chat and langgraph READMEs, the @threadplane
/render JSDoc that referenced it, the docs pages that described it, and the
blog tutorials whose bootstrap snippets would otherwise no longer compile.

The three pages that documented the API — chat/api/provide-chat,
chat/api/chat-config, and chat/guides/configuration — are deleted, dropped
from the docs nav, added to the retired-route pattern the public-copy
contract enforces, and permanently redirected (with their /api/markdown
mirrors) to chat installation so delivered links do not 404.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

* fix(chat): let an ancestor MARKDOWN_VIEW_REGISTRY override markdown views

<chat-streaming-md> provided MARKDOWN_VIEW_REGISTRY on its own component
injector from its own default, so a provider at the application root or on a
route was always shadowed and never reached the markdown node components.
The [viewRegistry] input was the only override that worked.

Resolution is now most-specific-first: the [viewRegistry] input, then a
registry found through skipSelf on an ancestor injector, then
cacheplaneMarkdownViews. The resolved value is still provided on the component
injector, so <chat-md-children> and the table-row view are unchanged, and
<chat> needs to forward nothing for an app-wide override to reach the markdown
it renders for assistant messages.

The new spec fails on the old resolution in two of its four cases (ancestor
provider, and the same through <chat>) and passes on the other two, which pin
the default and the input precedence.

Restores an accurate "App-wide override" section in the markdown guide, which
previously carried a Callout asserting the opposite, and corrects the
CHANGELOG entry that made the same claim.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

* refactor(chat): drop the unreachable 'mixed' content type, widen messageContent, tokenize the popup launcher

Three small cleanups:

- ContentType no longer carries 'mixed'. createContentClassifier never emitted
  it, so the `|| currentType === 'mixed'` branch in the delta path was dead and
  any consumer switch on it had a case no input reaches. The docs said as much
  and told readers not to branch on it; the member is simply gone instead.

- messageContent() takes { content: unknown } rather than LangChain's
  BaseMessage. Every caller in this library holds the runtime-neutral Message
  from agent.messages(), so ChatComponent.humanContent carried a cast and the
  docs told consumers to pass something other than the message they actually
  have. The function reads nothing but .content, so the structural parameter is
  the honest signature; the cast is gone.

- --tplane-chat-launcher-offset-x / -y (both 1rem) position the <chat-popup>
  launcher, which was pinned with hard-coded corner offsets. The popup window
  reads the horizontal one too, so it stays aligned when the launcher moves
  clear of a bottom bar or a consent banner.

The new message-utils spec fails to type-check against the old BaseMessage
signature (four errors under tsconfig.spec.json) and passes after. The new
chat-popup styles spec fails four of its five cases before the change, and its
window-alignment guard was mutation-checked by reverting that one declaration.

Regenerates the chat and render api-docs.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

* fix(chat): drop the now-unused @langchain/core peer dependency

Widening messageContent() to { content: unknown } removed the last
LangChain import from the published package, so @nx/dependency-checks
fails the declared peer. It stays a peer of @threadplane/langgraph,
which is why the install command still lists it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

Author: blove

apps/website/content/blog/2026-05-17-build-a-streaming-chat-ui-in-angular-with-langgraph.mdx

@@ -95,17 +95,15 @@ yarn add @threadplane/chat @threadplane/langgraph marked
 // app.config.ts
 import { ApplicationConfig } from '@angular/core';
 import { provideAgent } from '@threadplane/langgraph';
-import { provideChat } from '@threadplane/chat';
 
 export const appConfig: ApplicationConfig = {
   providers: [
     provideAgent({ apiUrl: 'http://localhost:2024' }),
-    provideChat({ assistantName: 'Assistant' }),
   ],
 };
 ```
 
-`provideAgent` is the transport. `provideChat` is the UI configuration. They are independent on purpose — you can use one without the other.
+`provideAgent` is the transport, and it is the only provider the chat components need. The UI is configured entirely through component inputs, so the two layers stay independent on purpose.
 
 </Step>
 <Step title="Create the agent in your component">

apps/website/content/blog/2026-05-21-build-fullstack-agentic-angular-apps-using-ag-ui.mdx

@@ -115,21 +115,19 @@ It is a peer dep so you can swap it.
 // app.config.ts
 import { ApplicationConfig } from '@angular/core';
 import { provideAgent } from '@threadplane/ag-ui';
-import { provideChat } from '@threadplane/chat';
 
 export const appConfig: ApplicationConfig = {
   providers: [
     provideAgent({ url: 'http://localhost:8000/agent' }),
-    provideChat({ assistantName: 'Astra' }),
   ],
 };
 ```
 
 That is the whole bootstrap.
 `provideAgent` is the AG-UI transport. It wraps the official `@ag-ui/client` `HttpAgent` and exposes the signal-shaped contract via DI.
-`provideChat` is the chat UI's configuration.
+It is the only provider the chat components need.
 
-Notice they are independent.
+Notice how little the two layers know about each other.
 `@threadplane/chat` does not know it is talking to an AG-UI backend.
 It just reads from the `Agent` contract.
 We will lean on that boundary later.

apps/website/content/blog/2026-05-28-human-in-the-loop-langgraph-agents-in-angular.mdx

@@ -117,12 +117,10 @@ That is why `request_approval` can branch on `decision["approved"]` and pick up
 ```ts
 // app.config.ts
 import { provideAgent } from '@threadplane/langgraph';
-import { provideChat } from '@threadplane/chat';
 
 export const appConfig: ApplicationConfig = {
   providers: [
     provideAgent({ apiUrl: environment.langGraphApiUrl }),
-    provideChat({}),
   ],
 };
 ```

apps/website/content/blog/2026-06-04-human-in-the-loop-ag-ui-agents-in-angular.mdx

@@ -205,12 +205,10 @@ Two details worth knowing:
 // app.config.ts — cockpit/ag-ui/interrupts/angular/src/app/app.config.ts
 import { ApplicationConfig } from '@angular/core';
 import { provideAgent } from '@threadplane/ag-ui';
-import { provideChat } from '@threadplane/chat';
 
 export const appConfig: ApplicationConfig = {
   providers: [
     provideAgent({ url: '/agent' }),
-    provideChat({}),
   ],
 };
 ```

apps/website/content/blog/2026-08-09-build-an-aws-strands-agent-ui-in-angular-with-ag-ui.mdx

@@ -230,14 +230,12 @@ Wire both packages into `app.config.ts`:
 ```ts
 import { ApplicationConfig } from '@angular/core';
 import { provideAgent } from '@threadplane/ag-ui';
-import { provideChat } from '@threadplane/chat';
 
 export const appConfig: ApplicationConfig = {
   providers: [
     provideAgent({
       url: 'http://localhost:8080/invocations',
     }),
-    provideChat({ assistantName: 'Strands Assistant' }),
   ],
 };
 ```

apps/website/content/blog/2026-08-13-angular-chat-app-tutorial-with-ag-ui.mdx

@@ -167,14 +167,12 @@ npm install @threadplane/chat @threadplane/ag-ui @ag-ui/client @ag-ui/core marke
 The provider is one line, because AG-UI's connection surface is one URL:
 
 ```ts
-import { provideChat } from '@threadplane/chat';
 import { provideAgent } from '@threadplane/ag-ui';
 
 export const appConfig: ApplicationConfig = {
   providers: [
     provideRouter(routes),
     provideAgent({ url: 'http://localhost:8000/agent' }),
-    provideChat({ assistantName: 'Librarian' }),
   ],
 };
 ```

apps/website/content/blog/2026-08-13-angular-chat-app-tutorial-with-langchain-langgraph.mdx

@@ -173,7 +173,6 @@ import {
   signal,
 } from '@angular/core';
 import { provideRouter } from '@angular/router';
-import { provideChat } from '@threadplane/chat';
 import { LANGGRAPH_THREADS_CONFIG, provideAgent } from '@threadplane/langgraph';
 
 import { routes } from './app.routes';
@@ -195,7 +194,6 @@ export const appConfig: ApplicationConfig = {
       onThreadId: (id) => ACTIVE_THREAD.set(id),
     }),
     { provide: LANGGRAPH_THREADS_CONFIG, useValue: { apiUrl: API_URL } },
-    provideChat({ assistantName: 'Assistant' }),
   ],
 };
 ```

apps/website/content/docs/a2ui/getting-started/introduction.mdx

@@ -94,7 +94,6 @@ Nothing in this file is specific to A2UI; the surfaces travel as assistant messa
 
 <ExampleCode file="app.config.ts" title="app.config.ts" />
 
-`provideChat({})` registers the chat composition defaults alongside it.
 
 ### Giving the chat composition a catalog
 

apps/website/content/docs/ag-ui/guides/client-tools.mdx

@@ -36,7 +36,7 @@ The server is a FastAPI application. `LangGraphAgent` wraps the compiled graph a
 
 ### Providing the agent
 
-`provideAgent()` from `@threadplane/ag-ui` registers the agent at the application root, and `provideChat({})` registers the chat defaults. The example resolves its URL at runtime because the host that serves the demo decides which runtime is attached; your own application passes a `url` directly.
+`provideAgent()` from `@threadplane/ag-ui` registers the agent at the application root, and it is the only provider the `<chat>` composition requires. The example resolves its URL at runtime because the host that serves the demo decides which runtime is attached; your own application passes a `url` directly.
 
 <ExampleCode file="app.config.ts" />
 

apps/website/content/docs/ag-ui/guides/interrupts.mdx

@@ -72,7 +72,7 @@ That wrapper is what turns a LangGraph pause into the AG-UI event described belo
 
 ### The agent provider
 
-`provideAgent()` registers the agent once for the whole application, and `provideChat({})` registers the configuration the `<chat>` composition reads, here left at its defaults. The example passes a factory because it resolves its endpoint at runtime from the host that serves the demo.
+`provideAgent()` registers the agent once for the whole application, and it is the only provider the `<chat>` composition requires. The example passes a factory because it resolves its endpoint at runtime from the host that serves the demo.
 
 <ExampleCode file="app.config.ts" />