Foundation Layer Implementation

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Phase 1: Foundation Layer

The foundation layer establishes the minimum V6 base inside the current repository shape. This phase clarifies seams, validation gates, and ownership in packages/sdk, packages/babysitter-agent, and plugins/*. It does not commit V6 to creating deferred top-level packages.

Current-Package Seam Clarification

**Runtime And Session Boundaries**

• Clarify which runtime concerns already belong to packages/babysitter-agent
• Isolate Pi wrapper, session handling, and structured event concerns behind internal module seams before considering any package move
• Reduce filesystem assumptions only where current commands and tests prove the change is safe
• Record candidate extraction boundaries as ADR-backed slices rather than package commitments

**Hook System**

• Tighten programmatic hook responsibilities in the current SDK and plugin surfaces
• Verify hook registration, invocation, and acknowledgment flows against existing runtime behavior
• Add or update configuration only where the current CLI and plugin model already require it

Infrastructure Foundation

**Compiler And Packaging Reality Checks**

• Validate agent-plugins-mux and related packaging flows against real plugin manifests and generated outputs
• Document import and ownership seams that already exist in the repo instead of inventing new package boundaries
• Add compatibility notes for any rename or extraction candidate that survives Phase 0 decision framing

**Platform Candidate Preparation**

• Describe plugin-system responsibilities in current-package terms
• Identify which platform concerns are internal packages/sdk or packages/babysitter-agent candidates versus actual plugins/* responsibilities
• Treat filesystem abstraction and plugin registration work as candidate slices only when they can be validated independently

Deliverables

• Updated seam map for runtime, session, and hook responsibilities in current packages
• ADR-backed first executable slice for the accepted @a5c-ai/babysitter-agent seam contract
• ADR-ready candidate slices for any later extraction or rename still worth considering
• Hook and packaging flows validated against existing commands and plugin outputs
• Any reduced-filesystem claim stated with a baseline, command, and rollback note

Technical Validation

**Documentation Consistency**: Foundation work must remain consistent with V6 Architecture Specification and Package Specifications

**Current-Behavior Checks**: Use current build, test, and plugin packaging commands as the source of truth for whether a seam is real

**Current Slice Command**: npm run verify:v6:seams is the repo-level validation gate for the accepted seam-contract slice

**Packaging Validation**: Compare compiler changes against existing manifest and install surfaces

**Performance Benchmarking**: Any runtime or session target must cite a baseline command before it becomes a success criterion

**Extraction Gate**: No deferred package name becomes part of this phase without a decision record that changes its state in the core V6 docs

Explicit Non-Deliverables

This phase does not create @a5c-ai/agent-runtime or @a5c-ai/agent-platform. Those names remain deferred vocabulary unless later decision records promote a specific slice into scope.

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**Related Documents**: Package Specifications | Testing Framework | Platform Layer