feat(state-hub): implement v0.5 — dynamic domains & multi-repo

Replaces the hardcoded 6-domain PostgreSQL ENUM with a first-class
`domains` DB table, and adds a `managed_repos` table for multi-repo
support per domain.

P1 — Domain as a DB entity:
- Migration b1c2d3e4f5a6: creates `domains` table, migrates topics.domain
  ENUM column to domain_id FK, drops the domain ENUM type
- Domain ORM model (api/models/domain.py) + Pydantic schemas
- Domain API router: GET/POST /domains/, GET/PATCH /domains/{slug}/,
  rename and archive endpoints with EP/TD cascade on rename
- Topic model updated: domain_id FK + @property domain_slug for
  backwards-compatible JSON serialization (field renamed domain → domain_slug)
- TopicCreate/TopicRead updated; seed.py rewritten to use FK lookup

P2 — Multi-repo support:
- ManagedRepo ORM model (api/models/managed_repo.py) + schemas
- Repo API router: GET/POST /repos/, GET/PATCH /repos/{slug}/, archive
- Makefile: add-domain, rename-domain, add-repo, list-repos targets
- register_project.sh: verify domain via /domains/ API + POST /repos/

P3 — MCP tools & live validation:
- 6 new MCP tools: list_domains, create_domain, rename_domain,
  archive_domain, list_domain_repos, register_repo
- EP/TD routers: replace hardcoded VALID_DOMAINS set with per-request
  DB lookup — returns 422 with list of valid slugs on unknown domain
- State summary: adds domains: list[DomainSummary] (slug, name,
  repo_count, active_workstream_count, ep_count, td_count)
- TOOLS.md updated with domain management section

P4 — Dashboard:
- New domains.md page with KPI row + domain cards + repo lists
- domains.json.py + repos.json.py data loaders
- Domains page added to observablehq.config.js nav
- workstreams.md, extensions.md, techdept.md: domain_slug fix +
  dynamic domain list loaded from /domains/ API (no longer hardcoded)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/routers/state.py

@@ -7,12 +7,17 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from api.database import get_session, engine
 from api.models.decision import Decision, DecisionStatus, DecisionType
+from api.models.domain import Domain
+from api.models.extension_point import ExtensionPoint
+from api.models.managed_repo import ManagedRepo
 from api.models.progress_event import ProgressEvent
 from api.models.task import Task, TaskPriority, TaskStatus
+from api.models.technical_debt import TechnicalDebt
 from api.models.topic import Topic, TopicStatus
 from api.models.workstream import Workstream, WorkstreamStatus
 from api.models.workstream_dependency import WorkstreamDependency
 from api.schemas.decision import DecisionRead
+from api.schemas.domain import DomainSummary
 from api.schemas.progress_event import ProgressEventRead
 from api.schemas.state import (
     DecisionTotals,
@@ -167,6 +172,9 @@ async def get_summary(session: AsyncSession = Depends(get_session)) -> StateSumm
 
     next_steps = await _derive_next_steps(session)
 
+    # Domain summary stats
+    domain_summaries = await _build_domain_summaries(session)
+
     return StateSummary(
         generated_at=datetime.now(tz=timezone.utc),
         totals=totals,
@@ -175,6 +183,7 @@ async def get_summary(session: AsyncSession = Depends(get_session)) -> StateSumm
         blocked_tasks=[TaskRead.model_validate(t) for t in blocked],
         recent_progress=[ProgressEventRead.model_validate(e) for e in recent],
         next_steps=next_steps,
+        domains=domain_summaries,
         open_workstreams=[
             WorkstreamWithDeps(
                 **WorkstreamRead.model_validate(w).model_dump(),
@@ -191,6 +200,53 @@ async def get_summary(session: AsyncSession = Depends(get_session)) -> StateSumm
     )
 
 
+async def _build_domain_summaries(session: AsyncSession) -> list[DomainSummary]:
+    """Compute per-domain stats for the state summary."""
+    domains_rows = await session.execute(
+        select(Domain).where(Domain.status == "active").order_by(Domain.name)
+    )
+    domains = list(domains_rows.scalars().all())
+
+    # Repo counts per domain
+    repo_counts = {r[0]: r[1] for r in await session.execute(
+        select(ManagedRepo.domain_id, func.count())
+        .where(ManagedRepo.status == "active")
+        .group_by(ManagedRepo.domain_id)
+    )}
+
+    # Active workstream counts per domain (join through topics)
+    ws_per_domain = {}
+    for domain_id, cnt in await session.execute(
+        select(Topic.domain_id, func.count(Workstream.id))
+        .join(Workstream, Workstream.topic_id == Topic.id)
+        .where(Workstream.status == WorkstreamStatus.active)
+        .group_by(Topic.domain_id)
+    ):
+        ws_per_domain[domain_id] = cnt
+
+    # EP counts per domain slug
+    ep_counts = {r[0]: r[1] for r in await session.execute(
+        select(ExtensionPoint.domain, func.count()).group_by(ExtensionPoint.domain)
+    )}
+
+    # TD counts per domain slug
+    td_counts = {r[0]: r[1] for r in await session.execute(
+        select(TechnicalDebt.domain, func.count()).group_by(TechnicalDebt.domain)
+    )}
+
+    return [
+        DomainSummary(
+            slug=d.slug,
+            name=d.name,
+            repo_count=repo_counts.get(d.id, 0),
+            active_workstream_count=ws_per_domain.get(d.id, 0),
+            ep_count=ep_counts.get(d.slug, 0),
+            td_count=td_counts.get(d.slug, 0),
+        )
+        for d in domains
+    ]
+
+
 _PRIORITY_RANK = {
     TaskPriority.critical: 0,
     TaskPriority.high: 1,
@@ -231,10 +287,10 @@ async def _derive_next_steps(session: AsyncSession) -> list[NextStep]:
         if task.id in seen_task_ids:
             continue
         ws = await session.get(Workstream, decision.workstream_id)
-        topic = await session.get(Topic, ws.topic_id) if ws else None
+        domain_slug = await _get_domain_slug_for_workstream(ws, session)
         steps.append(NextStep(
             type="resolved_decision",
-            domain=topic.domain if topic else None,
+            domain=domain_slug,
             workstream_id=ws.id if ws else None,
             workstream_title=ws.title if ws else None,
             workstream_slug=ws.slug if ws else None,
@@ -282,7 +338,7 @@ async def _derive_next_steps(session: AsyncSession) -> list[NextStep]:
         task = min(todo_tasks, key=lambda t: (_PRIORITY_RANK.get(t.priority, 99), t.created_at))
         if task.id in seen_task_ids:
             continue
-        topic = await session.get(Topic, from_ws.topic_id)
+        domain_slug = await _get_domain_slug_for_workstream(from_ws, session)
         blocker_slugs = ", ".join(
             (await session.get(Workstream, tid)).slug
             for tid in to_ws_ids
@@ -290,7 +346,7 @@ async def _derive_next_steps(session: AsyncSession) -> list[NextStep]:
         )
         steps.append(NextStep(
             type="dependency_cleared",
-            domain=topic.domain if topic else None,
+            domain=domain_slug,
             workstream_id=from_ws.id,
             workstream_title=from_ws.title,
             workstream_slug=from_ws.slug,
@@ -306,6 +362,17 @@ async def _derive_next_steps(session: AsyncSession) -> list[NextStep]:
     return steps
 
 
+async def _get_domain_slug_for_workstream(ws: Workstream | None, session: AsyncSession) -> str | None:
+    """Get the domain slug for a workstream via its topic."""
+    if ws is None or ws.topic_id is None:
+        return None
+    topic = await session.get(Topic, ws.topic_id)
+    if topic is None or topic.domain_id is None:
+        return None
+    domain = await session.get(Domain, topic.domain_id)
+    return domain.slug if domain else None
+
+
 @router.get("/next_steps", response_model=list[NextStep])
 async def get_next_steps(session: AsyncSession = Depends(get_session)) -> list[NextStep]:
     """Derive contextual next-action suggestions from current hub state.