diff --git a/PROJECT_GUIDELINES.md b/PROJECT_GUIDELINES.md
index 2fd3828..4b1a5b9 100644
--- a/PROJECT_GUIDELINES.md
+++ b/PROJECT_GUIDELINES.md
@@ -138,8 +138,42 @@ VERIFY → Compile successfully
   - Verify line numbers match intended section
 
 ### Documentation
-- ✅ Update **README.md** when users/admins need to be informed
-- ✅ Document API changes with Bruno collections
+
+**Documentation Structure** (updated with full docs system):
+- ✅ **README.md** - Project overview, quick start, and setup instructions only
+- ✅ **docs/** - Comprehensive documentation system with search
+- ✅ **docs/api/** - API reference documentation (split by endpoint/category)
+- ✅ **docs/devices/** - Device setup guides (KOBO, KOReader, etc.)
+- ✅ **docs/contributing/** - Development and contribution guides
+
+**Where to document changes**:
+
+| Change Type | Location | Examples |
+|-------------|----------|----------|
+| **User-facing features** | `docs/` or appropriate subdirectory | New features, UI changes, workflows |
+| **API endpoints** | `docs/api/<category>/<endpoint>.md` | New endpoints, modified responses, authentication changes |
+| **API behavior** | Update existing `docs/api/` files | Parameter changes, error codes, rate limits |
+| **Device setup** | `docs/devices/` | New device support, setup instructions |
+| **Development** | `docs/contributing/` | Build changes, architecture decisions |
+| **Quick start/setup** | `README.md` | Installation, environment setup, first-run |
+| **Breaking changes** | Both `README.md` and relevant `docs/` | Migration guides, deprecation notices |
+| **Bug fixes** | Update relevant `docs/` only if user-visible | Clarifications, troubleshooting additions |
+| **Bruno API tests** | `.bru` files alongside code | API contract testing, examples |
+
+**Documentation Update Workflow**:
+1. **Identify the audience** (end users, developers, API consumers)
+2. **Choose appropriate location** based on table above
+3. **Update documentation** before or with code changes
+4. **Verify documentation renders** at `/docs` endpoint
+5. **Test search** finds new/updated content
+6. **For API changes**: Update both `docs/api/` files AND Bruno `.bru` files
+7. **Commit separately** with clear message: `docs: <description>`
+
+**When in doubt**:
+- End-user visible → `docs/`
+- API reference → `docs/api/`
+- Setup/onboarding → `README.md`
+- Development related → `docs/contributing/`
 
 ### Process & Continuity
 - ✅ If mid-task and receive "no response", **continue the task**
@@ -216,7 +250,10 @@ git checkout -- internal/handlers/auth.go
   - Impact analysis
   - Alternative approaches considered
 - [ ] Plan git commit structure (multiple logical commits)
-- [ ] Identify if README.md needs updates
+- [ ] **Identify documentation location** (see Documentation section):
+  - [ ] User-facing feature → `docs/`
+  - [ ] UI/workflow changes → `docs/`
+  - [ ] Setup instructions → `README.md`
 
 ### Before Making Full-Stack Changes
 - [ ] Read current schema completely (if database changes)
@@ -224,6 +261,12 @@ git checkout -- internal/handlers/auth.go
 - [ ] Plan exact changes needed
 - [ ] Verify Podman will be used for builds
 - [ ] Plan git commit structure (multiple logical commits)
+- [ ] **Identify documentation location**:
+  - [ ] API changes → `docs/api/<category>/`
+  - [ ] New endpoints → Create new `.md` file in `docs/api/`
+  - [ ] API behavior → Update existing `docs/api/` files
+  - [ ] Breaking changes → Both `README.md` + relevant `docs/`
+  - [ ] Bruno `.bru` files → Update/create alongside API changes
 
 ### During Schema Changes (Full-Stack Only)
 - [ ] Read current schema completely
@@ -247,7 +290,13 @@ git checkout -- internal/handlers/auth.go
 - [ ] Run lint/typecheck if available
 - [ ] Ensure no secrets in changes
 - [ ] Verify logical commit structure
-- [ ] Update README.md if user-facing changes
+- [ ] **Update documentation** (see Documentation section):
+  - [ ] User-facing changes → `docs/`
+  - [ ] API changes → `docs/api/` + Bruno `.bru` files
+  - [ ] Setup/onboarding → `README.md`
+  - [ ] Development changes → `docs/contributing/`
+- [ ] **Verify docs render** at `/docs` endpoint
+- [ ] **Test docs search** finds new content
 
 ### Error Recovery Protocol (If Code Mistakes Occur)
 - [ ] **Stop immediately** - don't make more edits