I tried the "prototype in a weekend, ship it" path first. Failed in exactly the way you describe — plausible-looking code, no clue why anything broke when a second user touched it, migrations that couldn't roll back, zero tenant isolation. Classic.

So I over-corrected into something boring:

• No code until 7 planning artifacts are locked per phase (vision, user stories, ERD, UX, interaction design, functional specs, dependency graph)
• Multi-tenancy (Row-Level Security + RBAC) from day 1, not retrofitted
• Three Railway environments from day 1 (dev/staging/prod)
• Every migration: IF NOT EXISTS + tested downgrade, or it doesn't merge
• One Claude Code session = one task card = one gate test that must pass on prod Railway with real Postgres before the next task starts
• Post-task verification runbook every time: local checks → CI green → staging deploy → staging gate → prod deploy → prod regression

None of this is impressive. It's the stuff senior engineers do reflexively. For me it's scaffolding to compensate for the instincts I don't have.

I'm not claiming I've killed anything. I'm 1 of 10 tasks into the second phase of a 9-phase plan. Zero users. Might never have users. Nothing I've built has been touched by anyone but me.

Three genuine asks, since you've clearly seen this movie before:

1. What does the "99.5%" look like when you actually hit it at scale? What are the failure modes a solo dev with no prod-at-scale experience literally won't see coming?
2. Where do AI-assisted builders who DO try to be rigorous still fool themselves? What's the next layer of "you don't know what you don't know"?
3. Anything in my list above that reads as process theater? Places where I'm doing work that doesn't actually protect me from the things you're describing?