feat(hermes): add chat model picker

src-tauri/src/lib.rs

@@ -1707,6 +1707,8 @@ mod tauri_app {
                 acp_commands::acp_update_agent_config,
                 acp_commands::acp_update_hermes_config,
                 acp_commands::acp_update_kimi_code_config,
+                acp_commands::acp_hermes_model_options,
+                acp_commands::acp_set_hermes_model,
                 acp_commands::acp_fetch_kimi_models,
                 deepseek_settings_commands::acp_load_deepseek_model_catalog,
                 deepseek_settings_commands::acp_update_deepseek_model_catalog,

src-tauri/src/web/handlers/acp.rs

@@ -884,6 +884,47 @@ pub async fn acp_update_kimi_code_config(
     Ok(Json(affected))
 }
 
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct AcpHermesModelOptionsParams {
+    pub agent_type: AgentType,
+}
+
+pub async fn acp_hermes_model_options(
+    Extension(state): Extension<Arc<AppState>>,
+    Json(params): Json<AcpHermesModelOptionsParams>,
+) -> Result<Json<Option<acp_commands::HermesModelOptions>>, AppCommandError> {
+    let options = acp_commands::acp_hermes_model_options_core(params.agent_type, &state.db)
+        .await
+        .map_err(|e| AppCommandError::task_execution_failed(e.to_string()))?;
+    Ok(Json(options))
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct AcpSetHermesModelParams {
+    pub agent_type: AgentType,
+    pub model: String,
+}
+
+pub async fn acp_set_hermes_model(
+    Extension(state): Extension<Arc<AppState>>,
+    Json(params): Json<AcpSetHermesModelParams>,
+) -> Result<Json<usize>, AppCommandError> {
+    let emitter = state.emitter.clone();
+    let affected = acp_commands::acp_set_hermes_model_and_refresh(
+        params.agent_type,
+        &params.model,
+        &state.db,
+        &state.connection_manager,
+        &state.data_dir,
+        &emitter,
+    )
+    .await
+    .map_err(|e| AppCommandError::task_execution_failed(e.to_string()))?;
+    Ok(Json(affected))
+}
+
 #[derive(Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct AcpFetchKimiModelsParams {

src-tauri/src/web/router.rs

@@ -899,6 +899,14 @@ pub fn build_router(
             "/acp_update_kimi_code_config",
             post(handlers::acp::acp_update_kimi_code_config),
         )
+        .route(
+            "/acp_hermes_model_options",
+            post(handlers::acp::acp_hermes_model_options),
+        )
+        .route(
+            "/acp_set_hermes_model",
+            post(handlers::acp::acp_set_hermes_model),
+        )
         .route(
             "/acp_fetch_kimi_models",
             post(handlers::acp::acp_fetch_kimi_models),

src/components/canvas/canvas-conversation-surface.tsx

@@ -17,6 +17,10 @@ import { MessageListView } from "@/components/message/message-list-view"
 import { useAcpActions } from "@/contexts/acp-connections-context"
 import { useConnectionLifecycle } from "@/hooks/use-connection-lifecycle"
 import { useConversationDetail } from "@/hooks/use-conversation-detail"
+import {
+  HERMES_MODEL_CONFIG_ID,
+  useHermesModelOption,
+} from "@/hooks/use-hermes-model-option"
 import {
   acpStopAsyncTask,
   createChatConversation,
@@ -701,10 +705,37 @@ export function CanvasConversationSurface({
     () => conn.modes?.available_modes ?? [],
     [conn.modes]
   )
-  const connectionConfigOptions = useMemo(
+  const acpConfigOptions = useMemo(
     () => conn.configOptions ?? [],
     [conn.configOptions]
   )
+  // Same synthetic Hermes model option as the detail panel — the canvas surface
+  // hosts the same composer, so it must offer the same picker.
+  const { option: hermesModelOption, selectModel: selectHermesModel } =
+    useHermesModelOption({
+      agentType,
+      configOptions: acpConfigOptions,
+      status: conn.status,
+      reapplyConfig: conn.reapplyConfig,
+      canReconnect: !conn.isViewer && !conn.isDelegationChild,
+    })
+  const connectionConfigOptions = useMemo(
+    () =>
+      hermesModelOption
+        ? [...acpConfigOptions, hermesModelOption]
+        : acpConfigOptions,
+    [acpConfigOptions, hermesModelOption]
+  )
+  const handleConfigOptionChange = useCallback(
+    (configId: string, valueId: string) => {
+      if (configId === HERMES_MODEL_CONFIG_ID) {
+        selectHermesModel(valueId)
+        return
+      }
+      handleSetConfigOption(configId, valueId)
+    },
+    [handleSetConfigOption, selectHermesModel]
+  )
   const selectedModeId = useMemo(() => {
     if (connectionModes.length === 0) return null
     if (modeId && connectionModes.some((mode) => mode.id === modeId)) {
@@ -761,7 +792,7 @@ export function CanvasConversationSurface({
           selectorsLoading={selectorsLoading}
           selectedModeId={selectedModeId}
           onModeChange={handleModeChange}
-          onConfigOptionChange={handleSetConfigOption}
+          onConfigOptionChange={handleConfigOptionChange}
           agentType={agentType}
           availableCommands={conn.availableCommands ?? []}
           draftStorageKey={`canvas-draft:${contextKey}`}

src/components/chat/hermes-model-option-wiring.test.ts

@@ -0,0 +1,51 @@
+import { readFileSync } from "node:fs"
+import { resolve } from "node:path"
+import { describe, expect, it } from "vitest"
+
+import { HERMES_MODEL_CONFIG_ID } from "@/hooks/use-hermes-model-option"
+
+// Every surface that mounts the composer. A new one that forgets the routing
+// would send codeg's synthetic id to the agent; a new one that forgets the
+// option would silently drop the picker on that surface.
+const SURFACES = [
+  "src/components/conversations/conversation-detail-panel.tsx",
+  "src/components/canvas/canvas-conversation-surface.tsx",
+] as const
+
+const sources = SURFACES.map(
+  (path) => [path, readFileSync(resolve(process.cwd(), path), "utf8")] as const
+)
+
+describe("Hermes model option wiring", () => {
+  /**
+   * WHY: `configOptions` is the list the composer hands straight to the
+   * backend's `session/set_config_option` on a pick. codeg's synthetic Hermes
+   * model option is not one of those — Hermes never advertised it — so every
+   * surface that offers the option MUST also intercept its id. A surface that
+   * merges the option but routes it like an ACP one fails at the moment the
+   * user picks a model: the agent rejects an id it does not know, and the model
+   * silently stays where it was.
+   */
+  it.each(sources)(
+    "%s intercepts the synthetic id instead of forwarding it to the agent",
+    (_path, source) => {
+      expect(source).toContain("useHermesModelOption")
+      expect(source).toContain("hermesModelOption")
+      expect(source).toContain(`if (configId === HERMES_MODEL_CONFIG_ID)`)
+      // The composer must receive the intercepting handler, never the raw ACP one.
+      expect(source).toContain(
+        "onConfigOptionChange={handleConfigOptionChange}"
+      )
+      expect(source).not.toContain(
+        "onConfigOptionChange={handleSetConfigOption}"
+      )
+    }
+  )
+
+  // The prefix is the whole reason the interception is recognisable. Renaming
+  // the id without keeping it namespaced would make it indistinguishable from
+  // an agent-advertised option.
+  it("keeps the synthetic id namespaced to codeg", () => {
+    expect(HERMES_MODEL_CONFIG_ID).toBe("codeg:hermes-model")
+  })
+})

src/components/conversations/conversation-detail-panel.tsx

@@ -105,6 +105,10 @@ import {
 } from "@/stores/conversation-runtime-store"
 import { useShallow } from "zustand/react/shallow"
 import { useConversationDetail } from "@/hooks/use-conversation-detail"
+import {
+  HERMES_MODEL_CONFIG_ID,
+  useHermesModelOption,
+} from "@/hooks/use-hermes-model-option"
 import {
   buildSteerPayload,
   extractUserImagesFromDraft,
@@ -705,10 +709,40 @@ const ConversationTabView = memo(function ConversationTabView({
     () => effectiveModes?.available_modes ?? [],
     [effectiveModes]
   )
-  const connectionConfigOptions = useMemo(
+  const acpConfigOptions = useMemo(
     () => effectiveConfigOptions ?? [],
     [effectiveConfigOptions]
   )
+  // Hermes publishes no model selector over ACP, so codeg synthesizes one from
+  // the profile's own config.yaml (see `useHermesModelOption`). Null for every
+  // other agent, and for a Hermes build that ever starts advertising its own.
+  const { option: hermesModelOption, selectModel: selectHermesModel } =
+    useHermesModelOption({
+      agentType: selectedAgent,
+      configOptions: acpConfigOptions,
+      status: connStatus,
+      reapplyConfig: conn.reapplyConfig,
+      canReconnect: !conn.isViewer && !conn.isDelegationChild,
+    })
+  const connectionConfigOptions = useMemo(
+    () =>
+      hermesModelOption
+        ? [...acpConfigOptions, hermesModelOption]
+        : acpConfigOptions,
+    [acpConfigOptions, hermesModelOption]
+  )
+  // The synthetic option is codeg's, not the agent's: routing it to the ACP
+  // `session/set_config_option` would hand Hermes an id it never advertised.
+  const handleConfigOptionChange = useCallback(
+    (configId: string, valueId: string) => {
+      if (configId === HERMES_MODEL_CONFIG_ID) {
+        selectHermesModel(valueId)
+        return
+      }
+      handleSetConfigOption(configId, valueId)
+    },
+    [handleSetConfigOption, selectHermesModel]
+  )
   const connectionCommands = useMemo(
     () => (connIsForOtherAgent ? [] : (conn.availableCommands ?? [])),
     [connIsForOtherAgent, conn.availableCommands]
@@ -2210,7 +2244,7 @@ const ConversationTabView = memo(function ConversationTabView({
       selectorsLoading={selectorsLoading}
       selectedModeId={selectedModeId}
       onModeChange={handleModeChange}
-      onConfigOptionChange={handleSetConfigOption}
+      onConfigOptionChange={handleConfigOptionChange}
       agentType={selectedAgent}
       availableCommands={connectionCommands}
       attachmentTabId={tabId}
@@ -2347,7 +2381,7 @@ const ConversationTabView = memo(function ConversationTabView({
                 selectorsLoading={selectorsLoading}
                 selectedModeId={selectedModeId}
                 onModeChange={handleModeChange}
-                onConfigOptionChange={handleSetConfigOption}
+                onConfigOptionChange={handleConfigOptionChange}
                 agentType={selectedAgent}
                 availableCommands={connectionCommands}
                 attachmentTabId={tabId}