Software for work that can't go wrong.

Money, documents, approvals and handoffs. Pick a file to see what each product does; scroll down to open it.

HandselHandsel gives a creator and a brand one record for a product deal: terms both sides sign, every milestone and its status, and payouts that wait for approval.Open file

PROJECT FILELIVE

Trust and settlement

Handsel

Handsel gives a creator and a brand one record for a product deal: terms both sides sign, every milestone and its status, and payouts that wait for approval.

Status: Live

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Handsel · Product walkthrough

One record. Two signatures. No crossed wires.

Recorded from the latest Handsel build with demo data.

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Entrain · Prototype preview, in Chinese

Teach AI to fit your work, not your people to fit AI.

Recorded from the clickable prototype with demo data. Every feature carries its stage: built, prototype, planned or research.

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Four rules we decide by

Meaningful: Start where work already breaks. FleetMind's first job is turning receipts and proof of delivery into invoice-ready records.
Faster: Ship the smallest useful step, then improve it with the people using it. c4tsite is where we hear what to build next.
Easier: Fit the way people already work. Entrain teaches AI to fit a team's work, not the team to fit AI.
Safer: Nothing important moves without a person. An Entrain task starts only after someone confirms it; a Handsel payout waits for approval.

Six rules built into every C4T product, and where you can see them working.

Role-based access and trust boundaries
Only the right people can act, and every boundary is explicit.
Shown inEntrain: each assistant works only with the tools and run limit its project authorises (here, 80 steps and 1 hour). Pilot build, test identity.
Append-only audit events
Every action leaves a permanent, tamper-evident record.
Deterministic code for money and critical decisions
Critical outcomes are computed by code that always behaves the same way.
Shown inHandsel: a payout stays held until it is approved. Demo data.
Confidence thresholds, human review and fallback for AI
AI works within limits, with review and fallback when confidence falls.
Explicit authorization for sensitive operations
Sensitive operations require explicit, recorded permission.
Shown inHandsel: changed terms become one version that both sides sign. Demo data.
Evidence trails, monitoring, evaluation and rollback
Decisions stay observable, evaluated and reversible.
Shown inHandsel: one record shows both sides every milestone and its status. Demo data.