Scope
Codebase Cartographer
Maps the legacy system with the Context Engine: architecture, dependencies, conventions, and the risk in each repo.
Migrations
The rewrite that has outlived every roadmap becomes a program you can run.
Run framework upgrades, legacy rewrites, and platform migrations as one orchestrated program.
Cosmos maps the legacy system with the Context Engine, drafts a migration playbook your team approves, and fans a fleet of agents out across hundreds of repos in parallel waves. Every change is reviewed before merge.
cosmos / migrations / java-11-to-21
java-11-to-21.playbookapproved by @platform-team
- 01map removed-API usagecontext engine
- 02upgrade build · pin toolchaindeterministic
- 03migrate code · fix testsprompt
- 04open PRreview fleet
Wave 3 of 5412 / 640 repos migrated · parallel · isolated envs
- billing-servicemigrated · verified
- search-apimigrated · verified
- ledger-corereview fleet · 2/3
- batch-runnertests · 74s
- + 224 more reposwaves 4-5 · queued
Each wave updates the playbook · shared memory14:07 UTC
Meet Cosmos
A fleet of agents behind every wave.
Point Cosmos at the legacy estate. The Context Engine reconstructs the architecture and conventions nobody wrote down, the Planner turns them into a migration playbook your team approves, and the fleet executes it across repos in parallel waves with a full audit trail. Each migrated repo makes the next one faster.
What our customers are seeing
80%
Lower time and cost vs. manual migration
50%
Less engineer time on large-scale migrations
20×
Lower cost on a multi-million-line migration
Days
For upgrades that were scoped in months
One program takes the codebase from legacy to current.
Cosmos runs the whole arc. The Codebase Cartographer maps the legacy system, the Migration Planner drafts a per-repo playbook your team approves, Migration Authors execute it across repos in parallel waves, and the review fleet verifies every change before merge. Every wave feeds what it learned back into the playbook.
Migration lifecycleone program, end to end
Scope
Codebase Cartographer
Maps the legacy system with the Context Engine: architecture, dependencies, conventions, and the risk in each repo.
Playbook · Approval
Migration Planner
Drafts the per-repo playbook from the map: the transforms, the test strategy, and the order of the waves.
Human
Approves the playbook and the wave plan. Sets the rollout gates.
Fan-out · parallel
Migration Authors
Execute the playbook across repos in parallel waves, fixing tests and CI as they go. Each repo runs in an isolated environment.
Review
Review Fleet
Correctness and regression passes on every repo before merge. Failures route back to the authors with the diff attached.
Waves merged · playbook improved
Migration Memory
Every wave refines the playbook · Shared across the fleet
Fig 1 · Migration fleet
How the program runs
A program, not a project.
The consultancy model scales by adding people and ends in a risky cutover. A Cosmos program scales by adding compute, merges wave after wave behind the review fleet, and leaves the playbook and the memory in your org when the work is done.
The consultancy model
Built around headcount
- Headcount scales with the number of repos
- Knowledge leaves when the contract ends
- Risk concentrates in a big-bang cutover
Cosmos programs
Built around the playbook
- The fleet scales with compute, not headcount
- Playbook and memory stay in your org
- Waves merge continuously behind the review fleet
- Every change carries a full audit trail
Where programs start
Built for the programs teams used to hire out.
If the work spans more than a handful of repos, it runs better as a program. Three places most modernization efforts start.
Framework upgrades01
Every repo on the current major.
Java, Python, and Node LTS upgrades. Vue and React major versions. The playbook absorbs each repo's quirks instead of breaking on them, and the whole estate moves in parallel waves.
SCOPE: java 11 → 21 · 640 repos
Legacy rewrites02
Rewrites that preserve behavior.
COBOL-class systems and monoliths headed for services. The Context Engine reconstructs the architecture and conventions nobody wrote down, and the review fleet verifies behavior on every change.
SCOPE: cobol → java · 4.2M lines
Platform & API migrations03
Change the platform, keep the roadmap.
Cloud moves, internal API deprecations, and standardization across hundreds of repos run as background waves, so feature work never stops while the migration ships.
SCOPE: on-prem → cloud · 38 services
GitHubGitLabBitbucketTerraformGDPR · CCPA · HIPAA
Highly customizable to your estate.
Talk to Cosmos Advisor to shape the program around your estate: which repos move in which wave, what the playbook must verify, and who signs off at each gate. Keep your VCS, your CI, and your compliance posture.
Kubernetes estates are in scope, and every wave is logged to your SIEM.