# Inside the worktree Xirp handed to this session: fence the scope
nool announce intent --intent "Add idempotency keys to webhook handlers" --target-nodes src/billing/webhooks.ts
# Orient the agent from the ledger, not from a repository read
nool context "add idempotency keys to webhook handlers" --budget 3000
# Propose under the declared intent; the envelope and policy gates decide
nool propose --all --intent "Add idempotency keys to webhook handlers" --full
nool solidify --full --compact
# Or let Nool run the isolation as well, without a session manager
nool try new webhooks-idempotency --worktree --nodes src/billing/ --intent "Add idempotency keys to webhook handlers"
nool try promote webhooks-idempotencyNool does not care which harness ran the session. Claude Code, Codex and Gemini CLI sessions all propose the same way.
What Spotify Xirp is
Xirp is Spotify's vendor-neutral agentic development environment, opened as a public beta on 10 August 2026. It is a macOS application that requires a Spotify Technology account and is free during the beta; you bring your own Claude Code, Codex or Gemini CLI subscription. Its job is session management: one place to launch and watch many coding-agent sessions, each handed its own git worktree and branch so agents do not edit the same files at once. Spotify says the working state carries over when you switch harness mid-project, that one developer can run fifty or more sessions concurrently, and that more than 36,000 internal sessions ran through it before launch. Session transcripts can flow back into Spotify Portal for organisational visibility.
What Nool is
Nool is change control for the same agents. It does not host sessions or replace the terminal. It sits between an agent's intent and the repository: the agent announces intent and takes a fenced lease on the scope it will touch, works in an isolated worktree if you want one, and proposes its change under that intent. Nool computes the semantic blast radius, checks the change against the declared envelope and the team's policies, optionally runs a cross-vendor reviewer quorum, and seals what passes into a signed ledger that mirrors to Git. Replay, blame and bisect read that ledger back. It runs locally on macOS, Linux and Windows, needs no account to evaluate, and works with any agent that can run a CLI or call an MCP server.
Where they differ
Isolation versus permission. Xirp's worktree-per-session stops two agents from overwriting the same checkout, which is the first collision on any multi-agent team. It does not, from anything Spotify has published, decide whether two sessions' changes are compatible in meaning, stop a session from reaching beyond its task, apply a policy before merge, or attach review evidence to a change. Those are the second and third collisions, and they are Nool's core: leases fence scope while work is in flight, the envelope check refuses out-of-scope changes without a justification, and try promote stops with diff3 markers when two agents really did change the same symbol. Fifty sessions without those checks is fifty branches that merge cleanly and may still break the build.
Using them together
Run sessions in Xirp and govern them with Nool. Each Xirp session already lives in a worktree; add Nool's lease with nool announce intent or nool try new --nodes so the scope is fenced, propose from inside the session under the declared intent, and let the gates and the reviewer quorum decide what lands. Nool's ledger records the intent, blast radius and evidence for every change regardless of which harness produced it, which is the cross-vendor record Xirp's harness switching implies you will need. Nothing in Nool requires Xirp, and nothing in Xirp conflicts with Nool: one manages the terminal, the other manages the repository.
When to choose which
Choose Xirp when the pain is operational: too many terminal tabs, sessions you cannot find, harnesses you want to switch between without losing state, and a Mac on every desk. Choose Nool when the pain is what those sessions produce: agents colliding on shared code, changes that reach further than asked, merges that pass and break the architecture, and a security team asking for an audit trail. Choose both when you are running agents at the scale Xirp is built for, because at that scale the cost of an ungoverned merge is paid many times a day. Teams on Linux or Windows, or who cannot adopt a product that requires a vendor account, get the coordination half from Nool's own worktrees and fleets.
Spotify Xirp vs Nool, side by side
| Criterion | Spotify Xirp | Nool |
|---|---|---|
| What it is | Session manager for coding agents; macOS app in public beta since 10 August 2026 | Change control for coding agents; CLI and ledger on any Git repository |
| Platforms and account | macOS only; Spotify Technology account required | macOS, Linux and Windows; no account to evaluate |
| Agents | Claude Code, Codex, Gemini CLI | Any CLI or MCP agent, including those three and Cursor |
| Isolation | One git worktree and branch per session; 50-plus concurrent sessions | Isolated worktrees per try branch plus a fenced lease on the scope |
| Scope and conflict control | Not described | Leases with fencing numbers, semantic conflict detection, envelope check |
| Policy and review before merge | Not described | Deterministic gates, cross-vendor reviewer quorum, human holds |
| Record of what agents did | Session transcripts, optionally into Spotify Portal | Signed knots with intent, blast radius, evidence and attestations |
| Pricing | Free during beta; bring your own agent subscriptions | Free 30-day or 2,000-knot evaluation; organisations license through sales |
Frequently asked questions
- Is Nool an alternative to Xirp?
- Only for the coordination half. Nool's try branches and fleets give each agent an isolated worktree and a lease, so a team that wants isolation without a session manager, or that is not on macOS, gets it from Nool. Nool does not manage terminal sessions or switch harnesses mid-project.
- Does Nool work with sessions started in Xirp?
- Yes. Each Xirp session is an ordinary git worktree. Run nool announce intent inside it to fence the scope and nool propose to land the change through the gates; the harness that ran the session makes no difference to Nool.
- Does Xirp prevent merge conflicts?
- It prevents two sessions from editing the same checkout by giving each a worktree. From what Spotify has published, it does not check whether two sessions' changes are semantically compatible or gate what merges; that is what Nool's leases, envelope check and try promote do.
- Which should a security team look at?
- Nool, because it is the layer that decides what lands and records why, with deterministic gates, attestations and audit export. Xirp is a productivity tool for engineers running many sessions; the two address different questions.