docs: start CUST-WP-0025 hub-core extraction

docs/hub-core-extraction-boundary.md

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+# Hub-Core Extraction Boundary
+
+Last reviewed: 2026-06-06
+
+## Purpose
+
+This note starts `CUST-WP-0025-T05` by translating the original hub-core idea
+into a current implementation boundary. The State Hub implementation no longer
+lives under `the-custodian/state-hub`; the authoritative source checkout is
+`/home/worsch/state-hub`, and the planned package target is
+`/home/worsch/hub-core`.
+
+The extraction must preserve a clean FOS split:
+
+- `hub-core` owns reusable hub primitives.
+- `state-hub` becomes the first dev-hub implementation and keeps development
+  coordination concepts such as topics, workstreams, tasks, decisions,
+  dependencies, SBOM, token accounting, and kaizen agents.
+- Future hubs such as ops-hub and fin-hub depend on `hub-core` without pulling
+  in dev-hub coordination tables.
+
+## First Package Slice
+
+Create `/home/worsch/hub-core` as a uv-managed Python package with this initial
+layout:
+
+```text
+hub_core/
+  __init__.py
+  database.py
+  models/
+    __init__.py
+    base.py
+    domain.py
+    managed_repo.py
+    agent_message.py
+    tpsc.py
+  schemas/
+    __init__.py
+    domain.py
+    managed_repo.py
+    agent_message.py
+    tpsc.py
+  routers/
+    __init__.py
+    domains.py
+    repos.py
+    messages.py
+    tpsc.py
+    policy.py
+```
+
+This slice avoids the models that currently carry dev-hub foreign keys. It is
+large enough to prove packaging, import style, SQLAlchemy metadata ownership,
+router dependency injection, and State Hub compatibility before the more
+entangled surfaces move.
+
+## Extract Now
+
+These State Hub files are suitable for the first extraction after import-path
+rewriting and small router seams:
+
+| Source in `/home/worsch/state-hub` | Target role |
+| --- | --- |
+| `api/models/base.py` | Declarative base, timestamps, UUID helper. |
+| `api/models/domain.py` | Core domain identity; remove relationships to dev-hub-only models from core. |
+| `api/models/managed_repo.py` | Core repo registry; make `topic_id`, SBOM, and sync timestamps extension fields or keep them in dev-hub until a second pass. |
+| `api/models/agent_message.py` | Generic agent inbox and thread model. |
+| `api/models/tpsc.py` | Third-party service catalog/snapshot primitives. |
+| `api/schemas/domain.py` | Core domain schemas; split dev-hub counts from generic read models. |
+| `api/schemas/managed_repo.py` | Core repo schemas; keep dispatch/scope-health schemas in dev-hub. |
+| `api/schemas/agent_message.py` | Generic message schemas. |
+| `api/schemas/tpsc.py` | Generic TPSC schemas. |
+| `api/routers/messages.py` | Mostly self-contained generic router. |
+| `api/routers/tpsc.py` | Generic catalog and GDPR report router. |
+| `api/routers/policy.py` | Generic policy document router if policy roots become configurable. |
+
+## Needs An Adapter Seam
+
+These are still part of the target architecture, but the current State Hub
+implementation is coupled to dev-hub concepts:
+
+| Surface | Coupling to resolve |
+| --- | --- |
+| `Domain` and `domains.py` detail views | Counts topics, workstreams, extension points, and technical debt. Hub-core should expose a domain summary hook that dev-hub can implement. |
+| `ManagedRepo` | Contains `topic_id`, SBOM fields, and state-sync timestamps. Keep minimal repo identity in core, then add dev-hub extensions. |
+| `CapabilityRequest` | Points at workstreams and tasks. Hub-core needs generic context fields or optional extension references before extraction. |
+| `ProgressEvent` | Points at topics, workstreams, tasks, and decisions. Hub-core should define event identity, type, summary, detail, author, and timestamps, with hub-specific subject references added by each hub. |
+| MCP tools in `mcp_server/server.py` | Generic tools are mixed into a single dev-hub server module. T06 should create a base registration class that receives API client/config dependencies and lets dev-hub add its own tools. |
+
+## Keep In Dev-Hub
+
+The following State Hub areas should not move into hub-core during T05:
+
+- Topics, workstreams, tasks, decisions, dependencies, and flow state.
+- Extension points, technical debt, interface changes, SBOM, token events, and
+  contribution accounting.
+- Dashboard-specific loaders and Observable views.
+- Workplan-file parsing and consistency reconciliation.
+- Kaizen agents, scope health, dispatch views, and recently-on-scope reports.
+
+## Verification Plan
+
+The first hub-core commit should pass these checks before State Hub is refactored
+to import it:
+
+1. `python3 -m compileall hub_core`
+2. A minimal import test that imports every model, schema, and router module.
+3. SQLAlchemy metadata inspection proving the initial core tables are registered.
+4. A FastAPI smoke app that mounts the extracted routers with an injected
+   `get_session` dependency.
+5. `cd /home/worsch/state-hub && make test` remains green before and after the
+   editable `hub-core` dependency is introduced.
+
+## Next Step
+
+Create the `/home/worsch/hub-core` package with only the first package slice,
+commit that seed independently, then return to `/home/worsch/state-hub` for the
+first import-based refactor. Do not rename State Hub to dev-hub until T05-T08
+prove the shared package boundary.