Method getOrCreateSession

src/runtime/agent.ts:497–660

* Lazily create (or return existing) session for a channel.

(
    adapter: RuntimePlatform,
    channelId: string,
  )

   * Lazily create (or return existing) session for a channel.
   */
  private async getOrCreateSession(
    adapter: RuntimePlatform,
    channelId: string,
  ): Promise<ChannelSession> {
    const existing = this.channels.get(channelId);
    if (existing) return existing;

    const pendingCreation = this.pendingSessionCreations.get(channelId);
    if (pendingCreation) return pendingCreation;

    const createSessionPromise = (async () => {
      const { rootDir, provider, modelId, baseUrl } = this.options;

      // Use the shared AuthStorage instance (supports both API Key and OAuth)
      const authStorage = this.authStorage;

      const modelRegistry = ModelRegistry.create(authStorage);

      // When a custom base URL is provided, register a custom model entry with the
      // correct API protocol. Most proxies/local endpoints use the Completions API,
      // so default to "openai-completions" unless the user explicitly chose "openai-responses".
      if (baseUrl && modelId) {
        const customModel = createCustomProviderModelConfig(
          this.options,
          modelRegistry,
        );
        log(
          `[PackAgent] Registering custom model: `,
          JSON.stringify(customModel),
        );
        modelRegistry.registerProvider(provider, {
          baseUrl,
          apiKey: this.options.apiKey,
          models: [customModel],
        });
      }

      const resolvedModel = modelRegistry.find(provider, modelId);
      const model =
        resolvedModel && baseUrl && !this.options.apiProtocol
          ? { ...resolvedModel, baseUrl }
          : resolvedModel;
      if (resolvedModel && baseUrl) {
        log(
          `[PackAgent] Resolved ${provider}/${modelId} api=${resolvedModel.api} baseUrl=${baseUrl}`,
        );
      }

      const sessionDir = path.resolve(rootDir, "data", "sessions", channelId);
      fs.mkdirSync(sessionDir, { recursive: true });
      const sessionManager = SessionManager.continueRecent(rootDir, sessionDir);
      log(`[PackAgent] Session dir: ${sessionDir}`);

      const workspaceDir = path.resolve(
        rootDir,
        "data",
        "workspaces",
        channelId,