Deep Research API (deep-research-pro-preview-12-2025) — jobs stay in_progress indefinitely with complex prompts

I’m using the Deep Research API (deep-research-pro-preview-12-2025) via the @google/genai JS SDK (Interactions API) in a Next.js application.

The problem:
When I submit a detailed research prompt (approximately 2,000–3,000 characters), the interaction stays in in_progress status and never transitions to completed. My application polls interactions.get() every 10–30 seconds, but the status never changes, eventually hitting our 60-minute timeout.

What I’ve verified:

  • A simple prompt like “What is 1+1?” works perfectly — the interaction transitions to completed within a few minutes.
  • I tested this with raw curl commands (bypassing our application entirely), confirming the API itself responds correctly for simple inputs.
  • The simple prompt returns “status”: “in_progress” initially, then transitions to “status”: “completed” after a few minutes. This confirms our polling logic and status detection are correct.

What fails:
When using our production prompt (a structured research task asking for YouTube market research with specific output format requirements — tables, IDs, real video URLs, etc.), the interaction appears to stay in_progress indefinitely. We have never seen it reach completed or failed.

Our setup:

  • SDK: @google/genai (JS/TypeScript)
  • Agent: deep-research-pro-preview-12-2025
  • Parameters: background: true, store: true
  • HTTP timeout: 20 minutes (for individual requests)
  • Polling interval: 10–30 seconds (adaptive)

Questions:

  1. Is there a known issue with Deep Research jobs silently failing or hanging on complex prompts?
  2. Is there a maximum prompt length or complexity limit for the Deep Research agent?
  3. Is there any way to get more detailed status information (e.g., progress percentage, intermediate state) from the Interactions API?
  4. Are there known issues with the in_progress status not transitioning for certain types of requests?

Any guidance would be appreciated. Thank you.