Codex planning chat
Live work indicators, explicit approvals, interruption, retry, and Plan-scoped threads.
Free macOS alpha Powered by Codex
Plan, build, ship, and scale through one agentic workspace.
Mosaic gives AI-first developers a local, opinionated system for turning product intent into durable specifications, working designs, verified implementation, and guarded releases. Plan Studio is available today; the complete lifecycle is coming next.
Apple Silicon · macOS 13+ · Free alpha · Codex access required
Local-first artifacts
Built around Codex
Working prototypes
Review before acceptance
The product goal
One app. One system of context. Fewer handoffs.
Agentic development is fragmented across chat windows, design tools, terminals, specifications, repositories, CI, providers, and deployment dashboards. Mosaic is the place those decisions become a continuous, reviewable system.
- 01
Plan
Requirements, architecture, test logic, and interactive designs.
Available in alpha - 02
Build
Approved specs, isolated agents, worktrees, and traceable changes.
Coming soon - 03
Ship
Verification, pull requests, staging, and guarded releases.
Coming soon - 04
Scale
Environment contracts, providers, observability, and migrations.
Coming soon - 05
Operate
Attention, incidents, rollback, and portfolio health.
Coming soon
Product intentwhat and why
Approved contextdocuments + designs
Verified changeevidence + gates
Portfolio memoryrepeatable patterns
Available now
Mosaic Alpha · Plan Studio
Go from a rough idea to reviewed product context.
Plan with an agent, inspect every artifact it changes, experience the design as a working local prototype, and freeze approved revisions for reuse later.
Durable documentation
Brief, Requirements, Architecture, UX, Test Scenarios, Delivery Plan, and custom documents.
Working HTML designs
Self-contained interactive screens with realistic sample data—not static image generations.
Review in context
Comment on document anchors or select individual design elements for precise feedback.
Guarded revisions
Candidate previews, diffs, validation, immutable approvals, and revision history.
Controls that fit the task
Choose from supported Codex models, effort levels, and service speeds before each turn.
A deliberately focused alpha.Project creation, repository implementation, deployment, and provider writes are not enabled yet.
Review documents and realistic interactive screens in one focused workspace.
A cost-conscious alternative
Make your agentic design budget go further.
Mosaic Alpha is free and powered by the Codex access you already use.
Mosaic preserves accepted artifacts locally, resumes Plan-scoped threads, and lets you choose lower-usage supported Codex models and effort levels when a frontier model is unnecessary.
“In our internal alpha use, Mosaic has consumed materially less of our available agent usage than comparable Claude Design prototype sessions.”
Mosaic AlphaLocal planning workspace- Codex access required
- Selectable supported models
- Accepted artifacts stored locally
- Immutable reviewed revisions
CClaude DesignAnthropic Labs experiment
Paid planPro starts at $20/month in the US- — Pro, Max, Team, or Enterprise
- — Consumes that plan’s usage limits
- — Separate product and workflow
- — Availability may change
Usage varies by model, effort, prompt, and artifact size. Mosaic does not include Codex access and is not affiliated with Anthropic. Pricing checked August 13, 2026.
Why opinionated
Agents work better when the system has opinions.
Conventions reduce ambiguity. They keep every agent from inventing a different architecture, workflow, or release process—and turn ad-hoc code generation into a consistent engineering system.
Durable specifications
Keep product intent outside disposable chat context and preserve reviewed decisions.
Human-reviewed test logic
Agree on observable outcomes before an implementation agent starts changing code.
Known workspace boundaries
Give every agent a canonical monorepo, explicit ownership, and reusable patterns.
Provider contracts
Describe environments and integrations as repeatable contracts instead of one-off setup.
Evidence-backed delivery
Tie verification, generated artifacts, migrations, and releases back to the approved intent.
Portfolio consistency
Apply the same engineering system across every app without rebuilding the process each time.
IntentAgentsCodeEvidenceMosaicControl plane
MosaicControl planeConsistency compounds
One development system across an entire product portfolio.
Mosaic’s long-term value is not another agent chat. It is a shared operating model that lets every product inherit the same durable context, boundaries, verification, and release discipline.
Coming soon
Plan Studio is the first tessera.
The roadmap connects planning to development, delivery, environments, and operations. These are direction targets—not promised dates.
Project development
Turn approved context into governed changes.
- Plan handoff and new-project wizard
- Repository planning skills and spec gates
- Parallel worktrees and agent scheduling
- Changes, checks, and draft pull requests
- Portfolio Attention and Activity
Shipping + operations
Move verified work with explicit control.
- Staging and production environments
- GitHub delivery and guarded releases
- Rollback and incident workflows
- Provider action plans and approvals
- Observability and portfolio health
Roadmap target
Bolt-on provider catalog
Choose a capability. Let an agent wire the contract.
Agent-guided installation, environment configuration, verification, and approval-gated writes—without turning every integration into a bespoke project.
DatabasesData + migrations
First: Supabase / Postgres
NeonPlanetScaleTurso
AuthenticationIdentity + access
Targets: Supabase Auth
ClerkAuth0Better Auth
PaymentsBilling + revenue
First: Stripe
PaddleLemon Squeezy
Download Mosaic
Start with Plan Studio.
Grow into the complete agentic lifecycle as Mosaic’s guarded project capabilities arrive.
Available now
Mosaic for macOS
Plan locally on an Apple Silicon Mac with your compatible Codex access.
- Version
- 0.1.0-alpha.1
- Architecture
- Apple Silicon
- Requires
- macOS 13.0+
- Download
- 119 MB
SHA-256
b043ce737044c0dc5ea05db4f947bad9b1517cc9a1673207a4e5a81375466f4eUnsigned and not notarized. You’ll review installation guidance before the download starts.
Coming soon
Mosaic for Windows
The Windows build will follow after the macOS Plan Studio alpha is stable.
- Version
- —
- Architecture
- x64 / arm64
- Availability
- Not announced
- Status
- Roadmap
No waitlist or email collection. Watch the public release channel for updates.
FAQ
Useful context before you begin.
Early software deserves plain answers. If something is missing, check the release notes before installing.
What works in the alpha?+
Plan Studio is the only enabled product workspace. You can create Plans, work with Codex, generate and review documents and interactive HTML designs, comment, validate candidates, and approve immutable revisions. Projects, implementation, deployment, and provider writes are not enabled.
Is Mosaic free?+
Mosaic 0.1.0-alpha.1 is free for personal and internal commercial evaluation under the Alpha Evaluation License. Mosaic may introduce paid offerings later, but this alpha has no Mosaic subscription fee.
Does Mosaic include Codex?+
No. Mosaic connects to a compatible Codex CLI running on your Mac. You need Codex access through an eligible ChatGPT plan; any Codex usage remains subject to that plan’s terms and limits.
Where is Plan data stored?+
Plan metadata and artifacts stay on your Mac in Mosaic’s Application Support directory. Mosaic uses local SQLite storage, sandboxed previews, and macOS Keychain references for credentials.
Why is the macOS build unsigned?+
This is an early independent alpha and has not yet completed Apple signing and notarization. The download flow discloses this clearly, publishes a SHA-256 checksum, and documents Apple’s standard Control-click Open path without asking you to disable Gatekeeper.
How does Mosaic differ from Claude Design?+
Mosaic is a local planning workspace built around durable artifact revisions, selectable Codex models, review gates, and an eventual spec-driven development lifecycle. Claude Design is Anthropic’s separate design experiment. Mosaic is not affiliated with Anthropic.
When are Projects and Windows coming?+
Both are active roadmap targets, but Mosaic is not publishing promised dates yet. The alpha intentionally keeps those areas locked until their full safety and review workflows are ready.