Service 04
From person-month development to AI-agent development
Every time you look for a development vendor, the same frustrations return: quotes are high, deadlines slip, and specifications get lost in translation. That is not a staffing problem — it is the structure of person-month development.
FeelFlow's contract development is delegation, not coaching. AI agents built on AI Spec-Driven Development handle everything from requirements to implementation, review, testing, and operations. Your team is involved at just three points: shaping requirements, confirming the plan, and accepting the working product.
Implementation is 3x faster or more — and we publish the measured report behind that claim: 340,000 lines of code shipped in 18 days.
Traditional contract development is priced by securing people and multiplying their hours by a rate. The more people involved, the more meetings and handoffs — and all of that overhead lands in your quote.
You may be paying for waiting time, not code
When designers and implementers are different people, every change request means rescheduling humans: new meetings, availability gaps, priority negotiations. Most delays come from this structure, not from laziness.
Delays come from the structure, not the people
What sales heard becomes a PM's slide, then an engineer's design doc, then code. Each handoff shaves off intent. 'This isn't what we asked for' is the natural end state of that pipeline.
Products break down between 'we said' and 'we never heard'
Documentation drifts from the implementation until the real spec lives only in one vendor's memory — so no one else can take over, and price increases are hard to refuse. A specification kept in sync with the code removes the lock-in at its root.
With a living specification, lock-in has nothing to hold on to
Traditional contract development staffs every phase and bills for the hours. With AI Spec-Driven Development, AI agents do the work and people stand at just three decision gates.
Effort = headcount × time. Meetings, handoffs, and waiting time all end up in the quote.
AI agents work in parallel
You engage at three gates only. Waiting time never becomes cost.
No progress meetings to sit through, no spec walkthroughs, no test checklists. Your time goes only where a decision is needed.
Work with AI to turn rough ideas into a requirements document — this part we do together.
Review what will be built, in what order, and by when.
Check the working product. That is all we ask of your time.
If something doesn't match your expectations, just request changes — the AI handles the rework.
| Metric | Traditional | FeelFlow |
|---|---|---|
| Implementation speed | Scales with person-months | 3x+ (measured, report published) |
| Specification | Person-dependent, quickly stale | Source of truth driving every phase |
| Code review | Human-only, reviewer-dependent | AI on every PR, human at key decisions |
| Your workload | Meetings and checks at every phase | Three gates only |
| Maintenance | Depends on someone's memory | Continuously improved with specs + AI |
We published the full record of a project where AI agents shipped 340,000 lines of code in 18 days. The measured multiplier is far higher, but results vary by project — so we state a conservative "3x+ implementation speed."
Read the measured report (Japanese)FeelFlow offers the same AI Spec-Driven Development two ways: we install it into your team (coaching), or we use it to build for you (delegation — this page).
“We want to build it ourselves”
We install AI Spec-Driven Development into your team so you can run on your own. You build; we run alongside.
“We want it built for us”
FeelFlow's AI agents build and deliver — from requirements through implementation, testing, and operations. We build; you decide.
Tell us what you are trying to change — from your first AI use case to organization-wide adoption — and we'll map out a practical next step together.
