# Cronos Framework v2.1 is out: what changed and why every change cites a production cycle > Source: > Published: 2026-07-18 19:16:04+00:00 **TL;DR:** [Cronos](https://github.com/OvidiuMM/cronos-framework) — my open-source methodology for human-validated vibe coding — just shipped **v2.1**. It's the first release grounded in production evidence: four full cycles on real systems at a regulated SaaS company, and every amendment in the release cites the cycle that forced it. Here's the tour. Five-day engineering cycles where an AI agent does the heavy implementation and humans hold the gates: a plan approved before any code (Gate 1), an independent human validation before any ship (Gate 2). v2.0 defined the loop. v2.1 fixes what production broke — and adds the layer v2.0 was missing. The rhythm is no longer Monday–Friday. A cycle is five relative working days — **D1 through D5** — starting any day; weekends and holidays pause the clock. A Thursday start runs Thu, Fri, Mon, Tue, Wed. Kickoff on D1, Path Sync D2, verification D4, demo + release decision D5. The fixed five-day length stays: calendar independence is not permission to stretch to six. *Why:* "Monday kickoff" turned out to be a constraint with zero benefits — cycles ready on a Wednesday sat idle, and holidays broke the terminology. **Max 3 consecutive delivery cycles per person.** The next week is a mandatory **Technical Health Cycle** — and that cycle is the *scheduled owner* of the debt every retro defers. *Why:* Cronos blocks the implementer's calendar 100%. Chain that for a month and you get a tired, disconnected human operating your quality gates. Meanwhile, our E2E-testing gap was flagged in cycle 1, deferred in cycle 2, and still open in cycle 3 — because "Technical Health Cycle" existed in zero calendars. One rule fixes both: rest and debt repayment, same week. Three lines, async, end of each cycle day: ``` Landed: row 6 green (webhook signature verification) Next: row 7 — retry queue Friction: none ``` Explicitly **not a standup** — no meeting, no attendance. Two jobs: keep the deep-focus human visible to their team, and act as a soft tripwire — the same `Friction:` line two days running triggers a PM check-in *before* the hard reset trigger (4 hours in a loop) fires. `build:check && jest --runInBand` , and any suite failure with zero failing assertions is treated as a compile error.Any lesson that appears in two consecutive retrosmust be converted into an enforced mechanism — a guardrail entry, a CI check, or a skill — in the following cycle. *Why:* cycle 1's retro said, in bold, "scope your formatter." Cycle 2's team read it and ran the repo-wide formatter anyway. Written lessons don't propagate; machinery does. A twice-written lesson is a process bug. v2.1 formalizes the **AI Toolkit**: a versioned repo where cycle learnings graduate into `prompts/` (threshold: 1 proven use), `skills/` (threshold: a recurred lesson), and `knowledge/` (threshold: seen in 3 cycles — so first-cycle noise doesn't calcify into doctrine). Promotion runs only against *closed* cycles — and a cycle isn't closed until its retro is filled, which quietly fixes the "retro never gets written" problem too. This also patches the theory: the efficiency model's speedup factor is now **S(n) = S₀ + κ·K(n)** — it grows with the toolkit's asset stock. Without the layer, K = 0 and your speedup flatlines. Handy heuristic from the doc: *if you'd write a CLI for it, it's a skill; if it's a paragraph you keep retyping into chat, it's a prompt.* And stamp every saved prompt with the model you tested it on — prompt libraries rot silently as models change. New in `registry/claude-skills/cronos/` : a drop-in behavioral skill with **six operating modes** (Bootstrap → Mission Control → Implementation → Verification → Validation → Close), the gates enforced in-session, a failure-modes catalog distilled from the retros, and six paste-ready phase prompts. `examples/` — plan through retro, including a mid-cycle descope and a "Shipped with conditions" release.`Cronos_Framework_v2.1.pdf` with a new `.cursorrules` (never amend commits, never commit `.env` , narrow formatting, one concept per change).→ ** github.com/OvidiuMM/cronos-framework** — MIT, release `v2.1` . The full amendment rationale with per-cycle citations is in `doc/v2.1-amendments.md` v2.0 was a hypothesis. Four production cycles were the experiment. v2.1 is the revised hypothesis — and if you run it, your retros are welcome input for v2.2. What broke for *you*?