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, 147 insertions, 51 deletions

diff --git a/src/features/chat/ui/ModelSelector.svelte b/src/features/chat/ui/ModelSelector.svelte
index 1d06848..c66d3dd 100644
--- a/src/features/chat/ui/ModelSelector.svelte
+++ b/src/features/chat/ui/ModelSelector.svelte
@@ -1,11 +1,16 @@
 <script lang="ts">
   import type { ModelMetadata } from "@dispatch/transport-contract";
+  import type { NamedAgent, NamedAgentSelectionSnapshot } from "../../named-agents";
   import {
+    isNamedAgentSelection,
     isVisionModel,
     joinModelName,
     modelKeyLabel,
-    modelKeys,
     modelsForKey,
+    NAMED_AGENTS_PROVIDER,
+    namedAgentNames,
+    namedAgentSelectionLabel,
+    providerKeysWithNamedAgents,
     splitModelName,
   } from "../model-select";
 
@@ -14,6 +19,9 @@
     selected,
     onSelect,
     modelInfo = {},
+    namedAgents = [],
+    namedAgentSnapshot = null,
+    onSelectNamedAgent,
   }: {
     models: readonly string[];
     selected: string;
@@ -25,35 +33,88 @@
      * Optional — absent metadata → no badge (treated as non-vision).
      */
     modelInfo?: Readonly<Record<string, ModelMetadata>>;
+    /** The user-curated Named Agents (plan §6) offered under the synthetic provider. */
+    namedAgents?: readonly NamedAgent[];
+    /** The active conversation's Named Agent snapshot (null when not selected via one). */
+    namedAgentSnapshot?: NamedAgentSelectionSnapshot | null;
+    /** Called when a Named Agent is selected (the selector resolves it to a raw model + snapshot). */
+    onSelectNamedAgent?: (snapshot: NamedAgentSelectionSnapshot) => void;
   } = $props();
 
-  const keys = $derived(modelKeys(models));
+  // Whether the current selection is a Named Agent snapshot (the conversation was
+  // selected via one; its captured raw model equals `selected`).
+  const currentIsNamedAgent = $derived(isNamedAgentSelection(selected, namedAgentSnapshot));
+
+  const providerKeys = $derived(providerKeysWithNamedAgents(models));
   const current = $derived(splitModelName(selected));
   const keyModels = $derived(modelsForKey(models, current.key));
 
+  // The provider shown in the provider dropdown: the synthetic Named Agents
+  // provider when the selection is a Named Agent snapshot, else the raw key.
+  const currentProvider = $derived(
+    currentIsNamedAgent || current.key === NAMED_AGENTS_PROVIDER
+      ? NAMED_AGENTS_PROVIDER
+      : current.key,
+  );
+
+  const namedNames = $derived(namedAgentNames(namedAgents));
+
   // Whether the currently-selected full model name is vision-capable.
   const selectedVision = $derived(isVisionModel(modelInfo, selected));
 
-  // Whether the currently-selected full name is PRESENT in the catalog. When a
-  // saved credential/model disappears, we show it as unavailable rather than
-  // silently switching to something else.
-  const selectedUnavailable = $derived(selected !== "" && !models.includes(selected));
-  // The key part is itself missing from the catalog (e.g. a whole numbered
-  // OpenCode credential was removed).
-  const keyUnavailable = $derived(selected !== "" && !keys.includes(current.key));
-
-  // Switching key jumps to the first model available under it.
-  function selectKey(key: string): void {
-    if (key === current.key) return;
+  // Whether the currently-selected raw model is PRESENT in the catalog (only
+  // meaningful for a raw selection — a Named Agent snapshot resolves to a raw
+  // model that may have left the catalog).
+  const rawMissing = $derived(
+    !currentIsNamedAgent && selected !== "" && !models.includes(selected),
+  );
+  const keyUnavailable = $derived(
+    !currentIsNamedAgent && selected !== "" && !providerKeys.includes(current.key),
+  );
+
+  // Switching provider. Going TO the Named Agents provider: jump to the first
+  // Named Agent (mirrors selectKey jumping to the first model); the model
+  // dropdown then lists named names. Going to a raw provider: existing behavior.
+  function selectProvider(key: string): void {
+    if (key === currentProvider) return;
+    if (key === NAMED_AGENTS_PROVIDER) {
+      selectFirstNamedAgent();
+      return;
+    }
     const first = modelsForKey(models, key)[0] ?? "";
     onSelect(joinModelName(key, first));
   }
 
-  function selectModel(model: string): void {
+  // Selecting a raw model suffix under the current raw provider.
+  function selectRawModel(model: string): void {
     onSelect(joinModelName(current.key, model));
   }
 
-  // The full `<key>/<model>` name for a model suffix under the current key.
+  // Selecting a Named Agent name (under the synthetic provider): resolve it to a
+  // snapshot + raw model and report via onSelectNamedAgent.
+  function selectNamedAgent(name: string): void {
+    const agent = namedAgents.find((a) => a.name === name);
+    if (agent === undefined) return;
+    onSelectNamedAgent?.({
+      namedAgentId: agent.id,
+      namedAgentName: agent.name,
+      model: agent.model,
+    });
+  }
+
+  // Jump to the first configured Named Agent (used when the provider is switched
+  // to Named Agents), matching the raw-provider "jump to first model" behavior.
+  function selectFirstNamedAgent(): void {
+    const first = namedAgents[0];
+    if (first === undefined) return; // no named agents — the model dropdown shows the disabled placeholder
+    onSelectNamedAgent?.({
+      namedAgentId: first.id,
+      namedAgentName: first.name,
+      model: first.model,
+    });
+  }
+
+  // The full `<provider>/<model>` name for a raw model suffix under `current.key`.
   function fullNameFor(modelSuffix: string): string {
     return joinModelName(current.key, modelSuffix);
   }
@@ -62,58 +123,93 @@
 <div class="flex flex-col gap-2">
   <select
     class="select w-full"
-    value={current.key}
-    onchange={(e) => selectKey(e.currentTarget.value)}
+    value={currentProvider}
+    onchange={(e) => selectProvider(e.currentTarget.value)}
     aria-label="Key selector"
   >
-    {#if keyUnavailable}
+    {#if keyUnavailable && currentProvider !== NAMED_AGENTS_PROVIDER}
       <option value={current.key} disabled>{modelKeyLabel(current.key)} (unavailable)</option>
     {/if}
-    {#each keys as key (key)}
-      <option value={key}>{modelKeyLabel(key)}</option>
+    {#each providerKeys as key (key)}
+      <option value={key}>
+        {key === NAMED_AGENTS_PROVIDER ? "Named Agents" : modelKeyLabel(key)}
+      </option>
     {/each}
   </select>
+
   <select
     class="select w-full"
-    value={current.model}
-    onchange={(e) => selectModel(e.currentTarget.value)}
+    value={currentIsNamedAgent ? (namedAgentSnapshot?.namedAgentName ?? "") : current.model}
+    onchange={
+      currentIsNamedAgent
+        ? (e) => selectNamedAgent(e.currentTarget.value)
+        : (e) => selectRawModel(e.currentTarget.value)
+    }
     aria-label="Model selector"
+    disabled={currentProvider === NAMED_AGENTS_PROVIDER && namedAgents.length === 0}
   >
-    {#each keyModels as model (model)}
-      <option value={model}>
-        {model}{#if isVisionModel(modelInfo, fullNameFor(model))} · vision{/if}
-      </option>
-    {/each}
-    {#if selectedUnavailable && !keyUnavailable}
-      <option value={current.model} disabled>{current.model} (unavailable)</option>
+    {#if currentProvider === NAMED_AGENTS_PROVIDER}
+      {#if namedAgents.length === 0 && !currentIsNamedAgent}
+        <option value="" disabled>No named agents configured</option>
+      {:else}
+        {#each namedNames as name (name)}
+          <option value={name}>{namedAgentSelectionLabel(name)}</option>
+        {/each}
+        {#if currentIsNamedAgent && !namedNames.includes(namedAgentSnapshot?.namedAgentName ?? "")}
+          <!-- The selected Named Agent was renamed/removed — keep showing the
+               captured snapshot name rather than silently switching (plan §7). -->
+          <option value={namedAgentSnapshot?.namedAgentName ?? ""} disabled>
+            {namedAgentSelectionLabel(namedAgentSnapshot?.namedAgentName ?? "")} (unavailable)
+          </option>
+        {/if}
+      {/if}
+    {:else}
+      {#each keyModels as model (model)}
+        <option value={model}>
+          {model}{#if isVisionModel(modelInfo, fullNameFor(model))} · vision{/if}
+        </option>
+      {/each}
+      {#if rawMissing && !keyUnavailable}
+        <option value={current.model} disabled>{current.model} (unavailable)</option>
+      {/if}
     {/if}
   </select>
-  {#if selectedUnavailable}
+
+  {#if rawMissing}
     <div class="text-xs text-warning" role="status">
       Selected model “{selected}” is unavailable — choose another credential.
     </div>
   {/if}
-  {#if selectedVision}
-    <div class="flex items-center gap-1 text-xs text-base-content/60">
-      <svg
-        xmlns="http://www.w3.org/2000/svg"
-        viewBox="0 0 24 24"
-        fill="none"
-        stroke="currentColor"
-        stroke-width="2"
-        stroke-linecap="round"
-        stroke-linejoin="round"
-        class="h-3.5 w-3.5"
-        aria-hidden="true"
-      >
-        <path d="M1 12s4-8 11-8 11 8 11 8-4 8-11 8-11-8-11-8z"></path>
-        <circle cx="12" cy="12" r="3"></circle>
-      </svg>
-      <span>Vision — this model sees images natively</span>
-    </div>
-  {:else}
+
+  {#if currentIsNamedAgent}
     <div class="text-xs text-base-content/40">
-      Pasted images are auto-described (vision handoff)
+      Selected via <strong>Named Agents</strong> — snapshot of {namedAgentSnapshot?.namedAgentName}.
     </div>
   {/if}
-</div>
+
+  {#if !currentIsNamedAgent}
+    {#if selectedVision}
+      <div class="flex items-center gap-1 text-xs text-base-content/60">
+        <svg
+          xmlns="http://www.w3.org/2000/svg"
+          viewBox="0 0 24 24"
+          fill="none"
+          stroke="currentColor"
+          stroke-width="2"
+          stroke-linecap="round"
+          stroke-linejoin="round"
+          class="h-3.5 w-3.5"
+          aria-hidden="true"
+        >
+          <path d="M1 12s4-8 11-8 11 8 11 8-4 8-11 8-11-8-11-8z"></path>
+          <circle cx="12" cy="12" r="3"></circle>
+        </svg>
+        <span>Vision — this model sees images natively</span>
+      </div>
+    {:else}
+      <div class="text-xs text-base-content/40">
+        Pasted images are auto-described (vision handoff)
+      </div>
+    {/if}
+  {/if}
+</div>
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