fix: preserve Hermes runtime chat session state

.changeset/proud-horses-chat.md

@@ -0,0 +1,7 @@
+---
+"@runfusion/fusion": patch
+---
+
+summary: Preserve Hermes chat session state and project runtime routing more reliably.
+category: fix
+dev: Refreshes cached project chat plugin runners and hardens Hermes CLI session/error handling.

packages/dashboard/src/chat-project-services.ts

@@ -90,10 +90,16 @@ export function getOrCreateScopedChatManager(
   store: TaskStore,
   chatStore: ChatStore,
   pluginRunner?: ConstructorParameters<typeof ChatManager>[3],
+  refreshPluginRunner = false,
 ): ChatManager {
   const key = store.getFusionDir();
   const cached = scopedChatManagerCache.get(key);
-  if (cached) return cached;
+  if (cached) {
+    if (refreshPluginRunner && pluginRunner) {
+      cached.setPluginRunner(pluginRunner);
+    }
+    return cached;
+  }
   const agentStore = new AgentStore({ rootDir: store.getFusionDir() });
   const manager = new ChatManager(
     chatStore,

packages/dashboard/src/chat.ts

@@ -1075,6 +1075,14 @@ export class ChatManager {
     private taskStore?: TaskStore,
   ) {}
 
+  /**
+   * FNXC:ProjectChatRuntime 2026-07-05-18:10:
+   * Project chat managers can be created before a project engine finishes booting. Refreshing the plugin runner after construction prevents early requests from permanently binding Hermes/runtime hints to the global fallback runner; callers must only refresh from a confirmed project runner so transient engine unavailability cannot downgrade a scoped manager.
+   */
+  setPluginRunner(pluginRunner: ChatManager["pluginRunner"] | undefined): void {
+    this.pluginRunner = pluginRunner;
+  }
+
   private getPluginRunnerForSkillSelection(): Parameters<typeof buildSessionSkillContextSync>[3] {
     return this.pluginRunner?.getPluginSkills
       ? (this.pluginRunner as unknown as Parameters<typeof buildSessionSkillContextSync>[3])

packages/dashboard/src/routes/register-chat-routes.ts

@@ -115,7 +115,10 @@ export function registerChatRoutes(ctx: ApiRoutesContext, deps: ChatRouteDeps):
     }
     const projectStore = await getOrCreateProjectStore(projectId);
     const chatStore = getOrCreateScopedChatStore(projectStore);
-    return getOrCreateScopedChatManager(projectStore, chatStore, options?.pluginRunner);
+    const engine = options?.engineManager?.getEngine(projectId);
+    const projectPluginRunner = engine?.getPluginRunner?.();
+    const pluginRunner = projectPluginRunner ?? options?.pluginRunner;
+    return getOrCreateScopedChatManager(projectStore, chatStore, pluginRunner, Boolean(projectPluginRunner));
   }
   function validateModelPair(modelProvider: unknown, modelId: unknown): { modelProvider?: string; modelId?: string } {
     let normalizedProvider: string | undefined;

packages/engine/src/project-engine.ts

@@ -1042,6 +1042,11 @@ export class ProjectEngine {
     return this.runtime.getChatStore();
   }
 
+  /** Get the project-scoped PluginRunner (if initialized). */
+  getPluginRunner() {
+    return this.runtime.getPluginRunner();
+  }
+
   attachChatStore(chatStore: NotificationChatStore): void {
     this.notificationService?.attachChatStore(chatStore);
   }

packages/engine/src/runtimes/in-process-runtime.ts

@@ -1368,6 +1368,15 @@ export class InProcessRuntime
     return this.chatStore;
   }
 
+  /**
+   * Get the project-scoped PluginRunner (if initialized).
+   * Dashboard chat needs this runner, not the top-level PluginLoader, so
+   * runtime hints such as `hermes` can resolve plugin runtimes correctly.
+   */
+  getPluginRunner(): PluginRunner | undefined {
+    return this.pluginRunner;
+  }
+
   /**
    * Get the project's Scheduler instance.
    * @throws Error if runtime has not been started

plugins/fusion-plugin-hermes-runtime/src/__tests__/cli-spawn.test.ts

@@ -224,6 +224,18 @@ describe("parseHermesOutput", () => {
     expect(result.body).toBe("line1\nline2");
   });
 
+  it("accepts session_id emitted on stderr while keeping stderr out of the body", () => {
+    const result = parseHermesOutput("OK\n", "session_id: 20260427_120000_abcd12\n");
+    expect(result.sessionId).toBe("20260427_120000_abcd12");
+    expect(result.body).toBe("OK");
+  });
+
+  it("strips a leading stdout session_id marker from an empty assistant body", () => {
+    const result = parseHermesOutput("session_id: 20260427_120000_abcd12\n", "");
+    expect(result.sessionId).toBe("20260427_120000_abcd12");
+    expect(result.body).toBe("");
+  });
+
   it("throws when session_id line is missing", () => {
     expect(() => parseHermesOutput("some output without id", "stderr text")).toThrow(
       /missing session_id/,

plugins/fusion-plugin-hermes-runtime/src/__tests__/runtime-adapter.test.ts

@@ -68,6 +68,12 @@ describe("HermesRuntimeAdapter — promptWithFallback", () => {
     expect(onText).toHaveBeenCalledWith("hello from hermes");
     // Session id is captured for next call
     expect(session.sessionId).toBe("20260427_120000_abc123");
+    expect(session.messages).toEqual([
+      { role: "user", content: "first prompt" },
+      { role: "assistant", content: "hello from hermes" },
+    ]);
+    expect(session.state.messages).toBe(session.messages);
+    expect(session.state.errorMessage).toBeUndefined();
   });
 
   it("passes captured session id as --resume on subsequent calls", async () => {
@@ -94,6 +100,8 @@ describe("HermesRuntimeAdapter — promptWithFallback", () => {
     await expect(adapter.promptWithFallback(session, "p")).rejects.toThrow(
       /missing session_id/,
     );
+    expect(session.messages).toEqual([]);
+    expect(session.state.errorMessage).toBe("hermes: missing session_id");
   });
 
   it("does NOT call onText when body is empty", async () => {
@@ -110,6 +118,11 @@ describe("HermesRuntimeAdapter — promptWithFallback", () => {
     });
     await adapter.promptWithFallback(session, "p");
     expect(onText).not.toHaveBeenCalled();
+    expect(session.messages).toEqual([
+      { role: "user", content: "p" },
+      { role: "assistant", content: "" },
+    ]);
+    expect(session.state.errorMessage).toBeUndefined();
   });
 });
 

plugins/fusion-plugin-hermes-runtime/src/cli-spawn.ts

@@ -309,18 +309,19 @@ function stripChrome(text: string): string {
  * Returns `{ body, sessionId }` on success or throws with a descriptive error.
  */
 export function parseHermesOutput(rawStdout: string, rawStderr: string): HermesCliResult {
-  const cleaned = cleanText(rawStdout);
-  const match = SESSION_ID_RE.exec(cleaned);
+  const cleanedStdout = cleanText(rawStdout);
+  const cleanedCombined = cleanText([rawStdout, rawStderr].filter(Boolean).join("\n"));
+  const stdoutMatch = SESSION_ID_RE.exec(cleanedStdout);
+  const match = stdoutMatch ?? SESSION_ID_RE.exec(cleanedCombined);
 
   if (!match) {
-    const combined = [rawStdout, rawStderr].filter(Boolean).join("\n");
-    throw new Error(`hermes: missing session_id in output.\n${combined}`);
+    throw new Error(`hermes: missing session_id in output.\n${cleanedCombined}`);
   }
 
   const sessionId = match[1]!;
-  // Body is everything before the session_id line.
-  const sessionIdLineStart = cleaned.lastIndexOf("\nsession_id:");
-  const bodyRaw = sessionIdLineStart >= 0 ? cleaned.slice(0, sessionIdLineStart) : cleaned;
+  // Body is stdout before the session_id line. Recent Hermes builds can emit
+  // the session_id marker on stderr, so do not treat stderr as assistant text.
+  const bodyRaw = stdoutMatch ? cleanedStdout.slice(0, stdoutMatch.index) : cleanedStdout;
   const body = stripChrome(bodyRaw);
 
   return { body, sessionId };

plugins/fusion-plugin-hermes-runtime/src/runtime-adapter.ts

@@ -51,10 +51,12 @@ export class HermesRuntimeAdapter implements AgentRuntime {
   }
 
   async createSession(options: AgentRuntimeOptions): Promise<AgentSessionResult> {
+    const messages: unknown[] = [];
     const session: HermesStreamSession = {
       model: undefined,
       systemPrompt: options.systemPrompt,
-      messages: [],
+      messages,
+      state: { messages },
       apiKey: undefined,
       thinkingLevel: undefined,
       sessionId: "",
@@ -82,11 +84,22 @@ export class HermesRuntimeAdapter implements AgentRuntime {
     const promptWithContext = resumeId
       ? prompt
       : `${session.fusedSystemPrompt}\n\nUser request:\n${prompt}`;
-    const result = await invokeHermesCli(promptWithContext, this.settings, resumeId);
+    const userMessage = { role: "user", content: prompt };
+    session.messages.push(userMessage);
+    let result: Awaited<ReturnType<typeof invokeHermesCli>>;
+    try {
+      result = await invokeHermesCli(promptWithContext, this.settings, resumeId);
+      session.state.errorMessage = undefined;
+    } catch (err) {
+      session.messages.pop();
+      session.state.errorMessage = err instanceof Error ? err.message : String(err);
+      throw err;
+    }
 
     session.sessionId = result.sessionId;
     session.lastModelDescription = this.describeFromSettings();
 
+    session.messages.push({ role: "assistant", content: result.body });
     if (result.body) {
       session.callbacks.onText?.(result.body);
     }

plugins/fusion-plugin-hermes-runtime/src/types.ts

@@ -23,6 +23,10 @@ export interface HermesStreamSession {
   model: unknown;
   systemPrompt: string;
   messages: unknown[];
+  state: {
+    messages: unknown[];
+    errorMessage?: string;
+  };
   apiKey: string | undefined;
   thinkingLevel: string | undefined;
   sessionId: string;