Debugging Without Tunnel Vision

Trying new hypotheses but testing all of them with the same method is still tunnel vision, even though each attempt feels like progress. Cap it: 2 attempts per category below, then switch categories. (Seen in #3475 — three synthetic unit-test probes for a bug only visible in a real window.)

Categories

• Static/automated — unit tests, rendering-PNG tests, simplified scenarios
• Live observation — run + logs, breakpoints, user visually confirms
• Historical/comparative — bisect PRs/functionality, git log/blame, cross-backend diff
• Structural isolation — minimal repro outside the app/framework
• External verification — read the actual upstream source, its issue tracker
• Specialized tooling — GPU frame capture, other domain debuggers

Self-invoke on the 2nd same-category miss — don't wait for the user to point this out (happened on #3660: 4 rounds of GL/Skia-semantics patches before switching to live-observation logging).

Stop immediately if

• A sanity-check of your own method fails — the method is invalid, not "try harder within it."
• The symptom only shows in a context your current tool can't observe (e.g. a headless test can't see a real window) — switch categories, don't refine the probe.

Communicate

Narrate switches ("ruled out X, trying Y") instead of going silent. Keep working if confident; only stop to discuss when genuinely unsure which category to try next.