feat(named-agents): sidebar view, synthetic provider, auto-save, snapshot semantics

Implement the frontend of the Named Agents feature (plan §5-§9):
- New features/named-agents module: pure logic (types re-exported from
  @dispatch/wire + transport-contract, validation, provider/model options,
  snapshot helpers, network normalizers, auto-save status model) + an injected
  auto-save controller (name debounce, immediate provider/model save, monotonic
  stale-response guard) + the collapsible sidebar card view.
- Store: /named-agents CRUD + boot seed; selectModel(model, snapshot?) persists
  the raw model WITH the namedAgent snapshot; draft promotion carries it;
  refreshModel restores ModelResponse.namedAgent.
- Chat store setNamedAgent (sends namedAgent on chat.send); Tab.snapshot +
  setSnapshot (retained across rename/remove, persisted with tabs).
- Model selector: synthetic Named Agents provider ALWAYS first; selecting one
  resolves to the raw model + records a snapshot; a retained snapshot of a
  renamed/removed agent still displays as unavailable (plan §7).
- Composition root wires the view (viewKinds + loaded-modules manifest) + feeds
  the selector.

Tests: logic + controller + selector + app-store CRUD (1246 pass), typecheck 0,
biome clean (only pre-existing config infos pending a future migrate), build OK.

1 files changed, 16 insertions, 0 deletions

diff --git a/src/features/chat/store.svelte.ts b/src/features/chat/store.svelte.ts
index 24a1d06..c83c5fd 100644
--- a/src/features/chat/store.svelte.ts
+++ b/src/features/chat/store.svelte.ts
@@ -34,6 +34,7 @@ import {
   selectOrderedTurnMetrics,
 } from "../../core/metrics";
 import type { ConversationCache } from "../conversation-cache";
+import type { NamedAgentSelectionSnapshot } from "../named-agents";
 import type { ChatTransport, HistorySync, MetricsSync } from "./ports";
 
 export interface ChatStoreDependencies {
@@ -145,6 +146,15 @@ export interface ChatStore {
   cancelQueuedMessage(messageId: string): void;
   setModel(model: string): void;
   /**
+   * Set (or clear, with null) the Named Agent selection snapshot this chat sends
+   * with `chat.send` (plan §7). The backend persists it on the conversation at
+   * creation so it freezes the friendly id/name + resolved model — later edits to
+   * the Named Agent do not change this conversation's selection. The raw model
+   * (already set via `setModel`) is sent alongside; the snapshot is display/identity
+   * metadata that preserves HOW it was selected.
+   */
+  setNamedAgent(snapshot: NamedAgentSelectionSnapshot | null): void;
+  /**
    * Update the chat limit LIVE: re-normalizes, then adjusts the loaded window.
    * Lowering it unloads older committed chunks (deferred via the gate while the
    * reader is scrolled up, catching up on the next mutation). Raising it
@@ -180,6 +190,7 @@ export function createChatStore(deps: ChatStoreDependencies): ChatStore {
   let _pendingSync = $state(false);
   let _error = $state<string | null>(null);
   let _model = $state<string | undefined>(deps.model);
+  let _namedAgent = $state<NamedAgentSelectionSnapshot | null>(null);
   let disposed = false;
 
   let chatLimit = normalizeChatLimit(deps.chatLimit);
@@ -342,6 +353,7 @@ export function createChatStore(deps: ChatStoreDependencies): ChatStore {
         conversationId: deps.conversationId,
         message: text,
         ...(_model !== undefined ? { model: _model } : {}),
+        ...(_namedAgent !== null ? { namedAgent: _namedAgent } : {}),
         ...(deps.workspaceId !== undefined ? { workspaceId: deps.workspaceId } : {}),
         ...(images !== undefined && images.length > 0 ? { images: [...images] } : {}),
       };
@@ -379,6 +391,10 @@ export function createChatStore(deps: ChatStoreDependencies): ChatStore {
       _model = model;
     },
 
+    setNamedAgent(snapshot: NamedAgentSelectionSnapshot | null): void {
+      _namedAgent = snapshot;
+    },
+
     async setChatLimit(limit: number): Promise<void> {
       const prev = chatLimit;
       chatLimit = normalizeChatLimit(limit);