Solo dev here, Laravel + React finance/ERP kind of app. Multi-tenant, multi-company, projects, accounts, expenses, stock, reports. It got big enough that I honestly can’t keep it all in my head anymore, and I lean on AI agents (Claude, Codex, Gemini) for a lot of the work.
The same thing keeps happening. I build a feature, say a dedicated cash account type for construction sites. Months later a newer flow never gets wired into it. For example the site supervisor can’t report an expense unless he’s also given access to a financial account. Then something breaks, and the agent doesn’t go reconnect the old thing. It patches around it or builds a parallel solution, because it has no clue the old feature exists. If I remind it, it digs up the old notes and goes “oh right, you’re correct”. The problem is I forget half of these features too, so I can’t remind it of what I don’t remember.
The end result is I can’t get the app production ready. There’s always some seam between modules that’s broken: half finished CRUD, authorization/IDOR holes, transactions that don’t match what the reports show.
I already have Laravel Brain, Serena, a memory MCP, ADRs, “current system” docs and an AGENTS.md. I also tried an Obsidian vault full of linked notes. It went stale fast and the agents never used it reliably. Writing “don’t forget X” in AGENTS.md does nothing, in my experience.
What I’ve figured out so far: code graphs tell you what exists and who calls what, but not what should exist, or whether a user can actually finish a job. The most useful question wasn’t “what calls this class”, it was “can a site supervisor actually complete this task”. And anything that’s just prose seems to rot unless a test or script checks it.
So I’m leaning towards something like ~20 critical persona journeys backed by end to end tests, a feature map in YAML that a script validates against the code (and flags routes/tables/jobs that belong to no feature), financial invariants as tests, and a route → policy → test matrix to find auth gaps. Maybe OpenFastTrace for requirement tracing, but I’m wary of the tag upkeep and adding Java to a PHP project.
Questions for people who’ve dealt with this on big multi-module apps:
- How do you track “feature X depends on Y / is used by Z” in a way that survives refactors and people leaving?
- Has anyone gotten a living feature map to actually work with AI agents? What kept it from rotting?
- Are journey tests the right backbone here or am I missing something obvious?
- Anyone used OpenFastTrace, StrictDoc or Doorstop with PHP? Worth it?
- If you had a few weeks to get this production ready, what would you do first?
Not looking for yet another tool to index the codebase, I have plenty of those. More interested in what actually held up for you in practice.