Model iterates blindly on failures instead of diagnosing root cause

Feedback: Model fails to diagnose root causes, iterates blindly instead

Product: Claude Code (CLI)
Model: Claude Opus 4.6 (1M context)
Date: 2026-04-21

Problem

During a multi-hour session building a QBO OAuth integration, the model repeatedly failed to diagnose root causes before trying fixes. Instead of stopping to analyze WHY something failed, it would try a different approach, fail again, try another, and so on. This wasted hours of user time.

Specific examples from this session

1. OAuth "connection problem" error — Intuit returned a generic error. Instead of checking the one thing that would matter (are the credentials correct?), the model:

• Suggested the redirect URI was wrong (it wasn't)
• Suggested the app wasn't approved for production (it was)
• Suggested the wrong Intuit account was logged in (partially relevant but not the root cause)
• Built a Cloudflare tunnel to try a different domain (unnecessary)
• Changed the App URLs in the Intuit portal (unnecessary)
• Only AFTER all of that did it finally compare the client_id byte-by-byte and find that I (uppercase i) had been stored as l (lowercase L) — a 5-second check that would have saved 2+ hours

1. Redirect URI approach — Instead of researching Intuit's production OAuth requirements upfront (HTTPS required, no IPs, real domains only), the model tried:

• Self-signed cert on a Tailscale hostname (rejected by Intuit)
• localhost redirect (can't register in production)
• Only then tried Cloudflare tunnel (which worked)

Reading the Intuit docs first would have gone straight to the working solution.

1. Dashboard ack button — The model correctly identified the bug (missing JSON body) but only after first assuming completed tasks were the problem, then checking if the proxy path was wrong, then testing with truncated UUIDs. A single look at the browser network tab or the fetch() call would have found it immediately.

What should happen instead

When something fails, the model should:

1. Read the actual error — not just "it failed," but what specifically was returned
2. Check the simplest explanations first — wrong credentials, wrong URL, missing parameter
3. Verify assumptions before building — research the requirements of the external system (Intuit OAuth docs) before writing code
4. Never try a second approach until the first failure is fully understood — "it didn't work, let me try something else" is the worst debugging strategy

Impact

A task that should have taken ~1 hour took 4+ hours, most of it wasted on approaches that were doomed to fail because the root cause was never identified. The user had to relay debug information between multiple systems and people while the model thrashed.