diff --git a/TODO.md b/TODO.md
index 12fa854..c92c697 100644
--- a/TODO.md
+++ b/TODO.md
@@ -76,8 +76,8 @@ This file is the single source of truth for roadmap and delivery progress.
 - [x] [P2] i18n conventions docs (keys, namespaces, fallback, translation workflow)
 - [x] [P1] CRUD base patterns documentation and examples
 - [x] [P1] Environment and deployment runbook docs (dev/staging/production)
-- [ ] [P2] API and domain glossary pages
-- [ ] [P2] Architecture Decision Records (ADR) structure and first ADRs
+- [x] [P2] API and domain glossary pages
+- [x] [P2] Architecture Decision Records (ADR) structure and first ADRs
 
 ### Delivery Pipeline And Runtime
 
@@ -207,6 +207,7 @@ This file is the single source of truth for roadmap and delivery progress.
 - [2026-02-10] Public app now has a shared site layout (`banner/header/footer`), DB-backed header banner config, and SEO defaults (`metadata`, `robots`, `sitemap`).
 - [2026-02-10] Testing baseline now includes explicit RBAC regression checks, locale-resolution unit tests (admin/web), CRUD service contract tests, and i18n smoke e2e routes.
 - [2026-02-10] i18n conventions are now documented as an engineering standard (`docs/product-engineering/i18n-conventions.md`).
+- [2026-02-10] Docs now include a domain glossary, public API glossary, and ADR baseline with initial accepted decision (`ADR 0001`).
 
 ## How We Use This File
 
diff --git a/docs/.vitepress/config.mts b/docs/.vitepress/config.mts
index 7ee899f..90e3279 100644
--- a/docs/.vitepress/config.mts
+++ b/docs/.vitepress/config.mts
@@ -25,8 +25,10 @@ export default defineConfig({
           { text: "i18n Baseline", link: "/product-engineering/i18n-baseline" },
           { text: "i18n Conventions", link: "/product-engineering/i18n-conventions" },
           { text: "RBAC And Permissions", link: "/product-engineering/rbac-permission-model" },
+          { text: "Domain Glossary", link: "/product-engineering/domain-glossary" },
           { text: "Environment Runbook", link: "/product-engineering/environment-runbook" },
           { text: "Testing Strategy", link: "/product-engineering/testing-strategy" },
+          { text: "ADR Index", link: "/adr/" },
           { text: "Workflow", link: "/workflow" },
         ],
       },
@@ -36,7 +38,17 @@ export default defineConfig({
       },
       {
         text: "Public API",
-        items: [{ text: "Section Overview", link: "/public-api/" }],
+        items: [
+          { text: "Section Overview", link: "/public-api/" },
+          { text: "Glossary", link: "/public-api/glossary" },
+        ],
+      },
+      {
+        text: "ADR",
+        items: [
+          { text: "Index", link: "/adr/" },
+          { text: "0001 Monorepo Foundation", link: "/adr/0001-monorepo-foundation" },
+        ],
       },
     ],
     socialLinks: [{ icon: "github", link: "https://example.com/replace-with-repo" }],
diff --git a/docs/adr/0001-monorepo-foundation.md b/docs/adr/0001-monorepo-foundation.md
new file mode 100644
index 0000000..dc04fe7
--- /dev/null
+++ b/docs/adr/0001-monorepo-foundation.md
@@ -0,0 +1,37 @@
+# ADR 0001: Monorepo Foundation
+
+- Status: Accepted
+- Date: 2026-02-10
+
+## Context
+
+The CMS platform requires:
+
+- separate admin and public apps
+- shared domain contracts and data access
+- consistent tooling and CI quality gates
+- incremental delivery through MVP stages
+
+A fragmented multi-repo setup would increase coordination overhead and duplicate shared contracts.
+
+## Decision
+
+Adopt a Bun workspace monorepo with:
+
+- `apps/admin` and `apps/web` for runtime surfaces
+- shared packages (`@cms/content`, `@cms/db`, `@cms/crud`, `@cms/ui`, `@cms/i18n`)
+- shared quality tooling (Biome, TypeScript, Vitest, Playwright, Turbo)
+
+## Consequences
+
+### Positive
+
+- shared contract updates propagate in one change set
+- easier cross-app refactors and testing
+- single CI pipeline with consistent gates
+
+### Negative
+
+- stronger need for workspace discipline and clear boundaries
+- larger repository clone/build surface
+- potential for cross-package coupling if conventions are not enforced
diff --git a/docs/adr/README.md b/docs/adr/README.md
new file mode 100644
index 0000000..d2ae259
--- /dev/null
+++ b/docs/adr/README.md
@@ -0,0 +1,17 @@
+# ADR Index
+
+Architecture Decision Records (ADRs) capture important technical decisions and context.
+
+## Format
+
+- Numbered files: `0001-<short-title>.md`
+- Immutable once accepted (new ADRs supersede old decisions)
+- Include:
+  - Status
+  - Context
+  - Decision
+  - Consequences
+
+## Records
+
+- [0001 - Monorepo Foundation](./0001-monorepo-foundation.md)
diff --git a/docs/index.md b/docs/index.md
index 7a54842..04cd51a 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -7,6 +7,7 @@ Engineering documentation hub for this repository.
 - [Product / Engineering](/product-engineering/)
 - [Admin / User Guides](/admin-user-guides/)
 - [Public API](/public-api/)
+- [ADR Index](/adr/)
 
 ## Core Sources
 
diff --git a/docs/product-engineering/domain-glossary.md b/docs/product-engineering/domain-glossary.md
new file mode 100644
index 0000000..7358ee2
--- /dev/null
+++ b/docs/product-engineering/domain-glossary.md
@@ -0,0 +1,35 @@
+# Domain Glossary
+
+## Core Terms
+
+### Owner
+
+Highest-privilege admin role. Exactly one canonical owner must exist at all times.
+
+### Support User
+
+Hidden technical support account used for break-glass access and operational recovery.
+
+### Admin Registration Policy
+
+Runtime policy controlling whether `/register` can create additional admin users after owner bootstrap.
+
+### Protected Account
+
+Account that cannot be deleted/demoted through self-service flows (support + canonical owner).
+
+### CRUD Service
+
+Shared `@cms/crud` service abstraction combining schema validation, repository orchestration, and audit hooks.
+
+### Permission Scope
+
+RBAC access scope granularity: `own`, `team`, `global`.
+
+### Roadmap Source Of Truth
+
+`TODO.md` in repository root. Rendered in admin via `/todo`.
+
+### Header Banner
+
+Public-site announcement strip configured through `system_setting` key `public.header_banner`.
diff --git a/docs/product-engineering/index.md b/docs/product-engineering/index.md
index 7da1df0..4decf97 100644
--- a/docs/product-engineering/index.md
+++ b/docs/product-engineering/index.md
@@ -10,8 +10,10 @@ This section covers platform and implementation documentation for engineers and
 - [RBAC And Permissions](/product-engineering/rbac-permission-model)
 - [i18n Conventions](/product-engineering/i18n-conventions)
 - [CRUD Examples](/product-engineering/crud-examples)
+- [Domain Glossary](/product-engineering/domain-glossary)
 - [Environment Runbook](/product-engineering/environment-runbook)
 - [Testing Strategy Baseline](/product-engineering/testing-strategy)
+- [ADR Index](/adr/)
 - [Workflow](/workflow)
 
 ## Scope
@@ -23,6 +25,4 @@ This section covers platform and implementation documentation for engineers and
 
 ## Planned Expansions
 
-- Domain model and glossary
-- ADR (Architecture Decision Record) index
 - Operational playbooks (incident, rollback, recovery)
diff --git a/docs/public-api/glossary.md b/docs/public-api/glossary.md
new file mode 100644
index 0000000..6fab3e4
--- /dev/null
+++ b/docs/public-api/glossary.md
@@ -0,0 +1,43 @@
+# Public API Glossary
+
+## Scope
+
+Baseline terms for future public API design and integration discussions.
+
+## Terms
+
+### Public API
+
+Externally consumable endpoints intended for non-admin clients.
+
+### Resource
+
+Entity exposed by an API endpoint (for example: `page`, `media`, `news`).
+
+### Contract
+
+The stable request/response schema for an endpoint version.
+
+### Version
+
+Compatibility boundary for API contracts (for example: `v1`).
+
+### Authentication
+
+Identity verification mechanism for protected API routes.
+
+### Authorization
+
+Permission check determining whether an authenticated actor can access a resource/action.
+
+### Pagination
+
+Mechanism for splitting large result sets across requests.
+
+### Idempotency
+
+Property where repeating a request does not change final state beyond the first successful call.
+
+### Rate Limit
+
+Request threshold policy applied per consumer/time window.
diff --git a/docs/public-api/index.md b/docs/public-api/index.md
index e9d5336..3ca62f9 100644
--- a/docs/public-api/index.md
+++ b/docs/public-api/index.md
@@ -11,6 +11,11 @@ No stable public API surface is documented yet.
 - Add API docs when real endpoints are implemented and versioned
 - Use OpenAPI as source of truth for endpoint reference
 - Keep integration guides and authentication examples here
+- Use glossary terms consistently across API specs and guides
+
+## Reference
+
+- [Public API Glossary](/public-api/glossary)
 
 ## Notes