Skill: Cross-Repo Plan

Note: This skill extends the plan model beyond single repositories. The execution is inherently serial (one repo at a time in OpenCode). Use this for planning and tracking, not for simultaneous multi-repo execution.

What This Skill Does

Creates an implementation plan that spans multiple repositories. While the standard create-plan skill works within a single repo, many real-world features require coordinated changes across several repos (e.g., updating a shared library and then adapting all consumers).

Produces:

• Coordinator plan in the current repo with cross-repo phase dependencies
• Per-repo phase documents that reference the coordinator plan
• Execution order that respects inter-repo dependencies
• Global progress tracking across all involved repos

When to Use

• When a feature requires changes in 2+ repositories
• When a shared library update needs coordinated consumer updates
• When a migration spans multiple services
• When the user says "this affects repo X and repo Y"

Do NOT use this for changes that fit within a single repository — use create-plan instead.

Execution Model

• Always: the primary agent runs this skill directly.
• Rationale: cross-repo planning requires conversation context to understand repository relationships and user priorities. The plan structure is fundamentally a coordination document, not a deep codebase analysis.
• Limitation: OpenCode operates in one repo at a time. The coordinator plan lives in the "hub" repo; per-repo phases are executed when the user opens each respective repo.

Workflow

Step 1: Identify Repositories

Use the question tool to determine:

1. Which repositories are involved?
2. What is the relationship between them? (shared library → consumers, microservices, monorepo packages)
3. Which repo is the "hub" (where the coordinator plan will live)?
4. What is the execution order? (which repo must be changed first?)

Step 2: Map Cross-Repo Dependencies

For each repository, understand:

• What it provides to other repos (shared types, API contracts, libraries)
• What it consumes from other repos (imported packages, API calls)
• What the planned change affects in each repo

Build a dependency graph:

## Dependency Graph

repo-a (shared-lib)
  ↓ provides types + utilities
repo-b (api-service)
  ↓ provides API endpoints
repo-c (web-frontend)
  ↓ consumes API
repo-d (mobile-app)

Step 3: Design Phase Structure

Create phases that respect the dependency order:

• Phase 1: Changes in the upstream/provider repo (e.g., shared library)
• Phase 2: Changes in direct consumers
• Phase 3: Changes in downstream consumers
• Phase N: Integration testing across repos

Each phase is tagged with its target repository:

| Phase | Repo | Title | Depends On |
|-------|------|-------|------------|
| 1 | shared-lib | Update auth types | – |
| 2 | api-service | Adapt API to new types | Phase 1 |
| 3 | web-frontend | Update API client | Phase 2 |
| 4 | mobile-app | Update API client | Phase 2 |
| 5 | – (all) | Cross-repo integration test | Phases 2-4 |

Step 4: Create Coordinator Plan

Write the coordinator plan to plans/<name>/plan.md in the hub repo, using the coordinator-plan template (tpl-coordinator-plan.md). The template provides:

1. Repositories section: list all involved repos with their roles
2. Dependency graph: visual representation of repo relationships
3. Per-repo phases: each phase tagged with its target repo
4. Cross-repo acceptance criteria: conditions that span repositories
5. Execution order: step-by-step checklist per phase/repo

Step 5: Create Per-Repo Phase Documents

For each phase, create the standard phase and implementation plan documents. Add a header noting:

---
type: phase
plan: <plan-name>
repo: <target-repo>
coordinator: <hub-repo>
---

This allows resume-plan in any repo to find and reference the coordinator plan.

Step 6: Create Execution Checklist

Add a section to the coordinator plan's todo.md that tracks cross-repo execution:

## Cross-Repo Execution

### Phase 1: shared-lib
- [ ] Open shared-lib repo
- [ ] Run resume-plan (references this coordinator plan)
- [ ] Implement Phase 1
- [ ] Publish / push changes
- [ ] Verify consumers can access new version

### Phase 2: api-service
- [ ] Verify Phase 1 artifact is available (new package version / merged PR)
- [ ] Open api-service repo
- [ ] Run resume-plan
- [ ] Implement Phase 2

Step 7: Present and Confirm

Present the cross-repo plan to the user. Confirm:

• Are the repo dependencies correct?
• Is the execution order feasible?
• Are there deployment/release gates between phases?
• Who needs to be notified for each repo change?

Limitations

1. Serial execution: OpenCode works in one repo at a time. Cross-repo phases must be executed sequentially by switching repos.
2. No live status sync: the coordinator plan is a planning document, not a live dashboard. Status updates happen when the user runs update-plan in each repo.
3. Manual verification: cross-repo acceptance criteria must be verified manually (e.g., "API contract matches between service and client").
4. Hub repo responsibility: the coordinator plan lives in one repo. If the hub repo is not the one currently open, the user must remember to update it.

Rules

1. One coordinator, many targets: the coordinator plan lives in a single hub repo. Per-repo phases reference back to it.
2. Respect dependency order: never create a phase that runs before its upstream dependency is completed and available.
3. Each phase = one repo: a single phase should not span multiple repos. Split cross-repo work into repo-specific phases.
4. Standard templates: use the existing plan, phase, and implementation plan templates. The cross-repo additions are metadata (repo tag, dependency graph), not a new template.
5. Track availability, not just completion: a phase in repo-a is not just "completed" — its output must be "available" to repo-b (published package, merged PR, deployed service).
6. No built-in explore agent: do NOT use the built-in explore subagent type.