chore: workplan MRKD-WP-0001 + improved CLAUDE.md; document next steps

- workplans/MRKD-WP-0001-foundation-level1.md: 8-task workplan for
  Foundation & LEVEL1 Core (T01 scaffolding through T08 e2e harness)
- CLAUDE.md: added Planned Architecture section (interface table, FR
  domain map, key concepts, round-trip data flow) and Development
  Commands stubs derived from FRS v0.2
- problems/next-steps-2026-03-14.md: implementation guide for next
  session — task order, dep list, state-hub task UUIDs, quality gates

No code implemented yet; workstream registered in State Hub.

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

CLAUDE.md

@@ -1,6 +1,6 @@
 # CLAUDE.md
 
-This file provides guidance to Claude Code when working in this repository.
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
 
 ## What This Repo Is
 
@@ -18,6 +18,92 @@ Key artefacts already in this repo:
 
 ---
 
+## Planned Architecture
+
+markidocx is a **conversion pipeline** with three delivery interfaces over a shared functional core.
+
+### Interfaces
+| Interface | Purpose |
+|-----------|---------|
+| CLI | Local document workflows (`markidocx build`, `import`, `validate`, `compare`) |
+| REST service | Automation / pipeline integration |
+| MCP tools | Agent-accessible operations (same functional surface as CLI/REST) |
+
+All three interfaces expose the same functional model — no interface-specific logic should live outside its adapter layer.
+
+### Core Functional Domains (from FRS)
+| FR group | Domain |
+|----------|--------|
+| FR-100 | Project & manifest management |
+| FR-200 | Build / export (Markdown → DOCX) |
+| FR-300 | Import / round-trip (DOCX → Markdown) |
+| FR-400 | Multi-file composition & redistribution |
+| FR-500 | Feature-level enforcement (LEVEL1 / LEVEL3) |
+| FR-600 | Template & style family management |
+| FR-700 | Validation & drift analysis |
+| FR-1100 | Test & regression |
+| FR-1300 | Composite workflow orchestration |
+| FR-1400 | Evidence & report assembly |
+
+### Key Concepts
+- **Project manifest** — declares source files, feature level, and template/style family; drives all operations
+- **Feature levels** — LEVEL1 (headings, lists, tables, footnotes, images, links); LEVEL3 adds cross-refs, numbered figures, auto-diagrams, bibliography
+- **Document families** — three built-in: `article`, `book`, `website`; extensible via registration
+- **Source mapping** — multi-file imports must redistribute content back to origin files; fallback produces a merged single file
+- **Drift detection** — structural diff between original Markdown and re-imported result; reported as inspectable evidence
+
+### Round-trip data flow
+```
+manifest + Markdown sources
+    ↓  FR-100 (resolve project)
+    ↓  FR-200 (compose + export → DOCX)
+     [Word editorial review]
+    ↓  FR-300 (import DOCX → Markdown)
+    ↓  FR-400 (redistribute to source files)
+    ↓  FR-700 (validate + drift report)
+evidence artefacts
+```
+
+---
+
+## Development Commands
+
+> **Pre-implementation note:** No code exists yet. Commands below describe the intended interface; update this section as the package takes shape.
+
+```bash
+# Install in editable mode (once pyproject.toml exists)
+pip install -e ".[dev]"
+
+# Run tests
+pytest
+
+# Run a single test file
+pytest tests/path/to/test_file.py
+
+# Lint
+ruff check .
+
+# Type-check
+mypy src/
+
+# Start REST service (dev mode)
+markidocx serve --dev
+
+# CLI: build a document project
+markidocx build <manifest.yaml>
+
+# CLI: import an edited DOCX
+markidocx import <manifest.yaml> <edited.docx>
+
+# CLI: compare baseline vs re-import
+markidocx compare <manifest.yaml> <edited.docx>
+
+# CLI: run end-to-end regression
+markidocx test
+```
+
+---
+
 ## Custodian State Hub Integration
 
 This project is tracked as the **markitect** domain in the Custodian State Hub.