bookhoard/PROJECT_GUIDELINES.md

Combined Project Guidelines for Bookhoard

🚨 CRITICAL PROHIBITIONS (Never violate these)

Backend & Database

• ❌ NEVER modify backend code when working on frontend-only tasks
• ❌ NEVER modify database schema unless explicitly instructed for full-stack changes
• ❌ NEVER use Docker - use Podman only
• ❌ NEVER build server binaries locally - all builds through Dockerfile/docker-compose
• ❌ NEVER create new migration files - merge changes into current one until release
• ❌ NEVER use git checkout on schema files without checking what will be lost
• ❌ NEVER break existing functionality unless explicitly instructed
• ❌ NEVER duplicate business logic - keep logic in services, not handlers
• ❌ NEVER bypass service layer - all database operations must go through services

Testing

• ✅ ALWAYS use setupTestServer() helper from cmd/server/tests/test_helpers.go
• ✅ Share one test setup across all subtests - call setupTestServer() once at test function level, not per subtest
• ✅ Prefer table-driven tests - use t.Run() with test cases instead of duplicate test functions
• ✅ Configure database pools efficiently - use max_conns=1 for test pools (via pgxpool.ParseConfig()) to prevent connection exhaustion
• ❌ NEVER create separate pgxpool per test - each pool creates 4 connections by default; 78 tests = 312 potential connections > PostgreSQL's 100 limit
• ❌ NEVER call setupTestServer() in loops or within subtests - creates unnecessary database pools and exhausts connections
• ✅ DO verify tests pass - run full test suite before completing work
• ✅ Use t.Cleanup() properly - the TestServerSetup pattern automatically handles cleanup via t.Cleanup()

Frontend & Styling

• ❌ NEVER modify backend/API for frontend features without user confirmation
• ❌ NEVER use custom CSS - TailwindCSS classes only
  • ⚠️ EXCEPTION: templates/error.templ may have inline CSS because error pages must work when main app fails (404, server errors, CSS fails to load)
• ❌ NEVER use JavaScript - convert all to TypeScript
  • ⚠️ EXCEPTION: Inline JS function calls in HTML attributes (e.g., onclick="myFunction()") are acceptable for simple interactions
• ❌ NEVER use Object-Oriented Programming (no classes, inheritance, or this-capture)
• ✅ DO use procedural/imperative style as your default
• ✅ DO borrow functional techniques when they simplify code
• ✅ DO avoid ideological purity - the best paradigm is the one that fits the problem
• ❌ NEVER add new Dockerfiles without user confirmation
• ❌ NEVER fetch initial data via AJAX on page load - use server-side rendering instead
• ❌ NEVER break progressive enhancement - pages must work without JavaScript

Note: Go methods in the backend are fine and encouraged. This guideline applies to TypeScript/JavaScript frontend code only.**

General

• ❌ NEVER skip pre-commit hooks unless explicitly requested
• ❌ NEVER force push to main/master branches
• ❌ NEVER commit files with secrets (.env, credentials.json, etc.)
• ❌ NEVER make assumptions - ask clarifying questions when uncertain
• ❌ NEVER delete code without reading full context first (minimum 20 lines before/after)
• ❌ NEVER make cascading fix-up edits without git diff review
  • After compilation error: STOP, review git diff, understand full impact
  • Use revert/reapply pattern instead of blind fixes
• ❌ NEVER skip post-edit verification - must compile after each file edit
• ❌ NEVER run git commands concurrently - always run sequentially:
  • Run git add <files> and wait for completion
  • Run git commit -m "<message>" and wait for completion
  • Run git push and wait for completion
  • Never use && to chain git commands together
• ✅ Make good organized git commits for the entire project (not just what you changed) and push - run git add, commit, push sequentially as separate commands, no need to repeatedly check status
• ✅ Indentation is always 2 spaces unless the language prohibits it

Cascading Fix-up Pattern (PROHIBITED)

WHAT NOT TO DO - This caused critical bugs:

// ❌ WRONG: Blindly making fixes after compilation error

Edit 1: Delete deprecated code
[Compilation error: undefined Register]

Edit 2: Try to fix error (over-broad deletion)
[More errors: undefined Login, GetProfile, etc.]

Edit 3: Try to fix again (worse damage)
[Even more errors: major functionality broken]

CORRECT APPROACH:

// ✅ CORRECT: Stop, understand, then fix deliberately

Edit 1: Delete deprecated code
[Compilation error: undefined Register]

STOP → Review git diff → Understand Register was accidentally deleted
RESTORE → Get exact Register function from git history
VERIFY → Compile successfully

Key Principle: When compilation errors occur after edits:

1. STOP - Don't make more edits
2. ANALYZE - Use git diff to understand what was changed
3. RECOVER - Restore what was accidentally deleted/broken
4. VERIFY - Compile and test before proceeding

---

🎯 CONTEXT-SPECIFIC RULES

When Working on Frontend-Only Tasks

• DO NOT touch backend code - handlers, services, database layer
• DO NOT modify API routes - use existing endpoints only
• DO NOT change database schema - work with existing structure
• If backend change seems necessary:
  1. Identify the required change
  2. Explain why you need it
  3. Provide impact analysis
  4. ASK FOR USER CONFIRMATION before proceeding

When Working on Full-Stack Tasks

• Backend changes are allowed when explicitly part of the task
• Still follow all database protocols (atomic changes, validation, etc.)
• If modifying database schema: Update local database after schema.sql changes (see Database Operations section)
• Still use Podman for all builds
• Still include Bruno tests for API changes

---

✅ MANDATORY REQUIREMENTS

Database Operations (Full-Stack Tasks Only)

• ✅ Follow pgx v5 standards for all database operations
• ✅ Treat schema changes as ATOMIC - complete success or complete rejection
• ✅ ⚠️ CRITICAL: This is a pre-production application (NO production deployments exist)
  • When database/schema/schema.sql is updated, local databases must be updated
  • Option 1 (Recommended): Recreate database with fresh schema:

    podman compose down -v  # Delete volumes (WARNING: loses all data)
    podman compose up -d    # Start fresh with new schema
    

  • Option 2: Manually apply schema changes to existing database using psql
  • DO NOT create migration files - no legacy schema support needed
• ✅ Use pre-change checklist: read schema → identify columns → plan changes → verify → read back
• ✅ Post-change validation: ensure schema.sql, models.go, and queries.sql are in sync

Build & Deployment

• ✅ Use Podman exclusively (not Docker)
• ✅ All builds through existing Dockerfile and docker-compose.yml
• ✅ Stop building server binaries - everything goes through containers

API Changes (Full-Stack Tasks Only)

• ✅ Include Bruno OpenCollection YAML requests with all API documentation
• ✅ Tests must be comprehensive and cover three contexts: no user, user, and admin
• ✅ Maintain backward compatibility for mobile apps and external consumers

Frontend & Styling

• ✅ Always use TailwindCSS classes for all styling
• ✅ Convert all JavaScript to TypeScript
• ✅ Never use Object-Oriented Programming (no classes, inheritance, or this-capture)
• ✅ Use procedural/imperative style as your default
• ✅ Borrow functional techniques when they simplify code
• ✅ Avoid ideological purity - the best paradigm is the one that fits the problem
• ✅ Extract domain concepts/types only when clearly beneficial - apply YAGNI, avoid over-engineering
• ✅ Render initial data server-side in Go templates for fast page loads
• ✅ Use JavaScript/HTMX for CRUD operations (create, update, delete)
• ✅ Ensure progressive enhancement - pages work without JavaScript

Service Layer Architecture

• ✅ All business logic in services - never in handlers
• ✅ Services must be reusable by both SSR handlers and API endpoints
• ✅ Database operations through services only - never direct from handlers
• ✅ When adding features: Add service logic → Create API endpoint → Use SSR for initial render → Use JS for updates

Code Organization

• ✅ Minimize project structure changes
• ✅ Place new files in contextually appropriate directories
• ✅ Follow KISS, DRY, and YAGNI principles
• ✅ Use multiple, logical git commits with clear messages
• ❌ NEVER duplicate types between handlers and templates - define data types in handlers, reuse directly in templates
• ✅ DO share handler types with templates - templates should use handlers.CollectionData, handlers.BookInfo, etc. directly
• ❌ NEVER create parallel type systems - no templates.XxxData types for data that originates from handlers
• ✅ DO enhance handler types with template-specific fields when needed (e.g., add Icon, FormattedDate fields to handlers structs)
• ✅ DO keep template-only types in templates package - PageData, UnsafeHTML, and template-specific utilities are appropriate
• ❌ NEVER create conversion helper functions to map between handler and template types - use handler types directly

Configuration & Environment

• ✅ If .env is missing, auto-generate secure values
• ✅ Never commit secrets to repository

Code Modification Safety

• ✅ Post-Edit Verification (MANDATORY for ALL file modifications):
  • Run go build for affected packages immediately after each edit
  • Review git diff filename to verify only intended changes
  • Validate functionality still works as expected
  • Never proceed to next file until current edit is verified
• ✅ Backup Before Large Changes:
  • Create a stash: git stash push -m "Pre-cleanup snapshot" before removing >50 lines
  • Or create a backup branch: git branch backup-before-cleanup
  • This allows instant recovery if mistakes occur
• ✅ Large Deletion Safety Pattern:
  • Read at least 20 lines before/after deletion target
  • Include unique identifiers in match (function signatures, specific comments)
  • Use narrow matches - avoid generic patterns
  • Verify line numbers match intended section

Documentation

Documentation Structure (updated with full docs system):

• ✅ README.md - Project overview, quick start, and setup instructions only
• ✅ docs/ - Comprehensive documentation system with search
• ✅ docs/developer/api/ - API reference documentation (split by endpoint/category)
• ✅ docs/user/ - User-facing features, guides, and workflows
• ✅ docs/user/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/user/	New features, UI changes, workflows
API endpoints	docs/developer/api/<category>/<endpoint>.md	New endpoints, modified responses, authentication changes
API behavior	Update existing docs/developer/api/ files	Parameter changes, error codes, rate limits
Device setup	docs/user/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 OpenCollection YAML tests	.yml files in bruno folder in appropriate folder/sub-folder	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/developer/api/ files AND Bruno OpenCollection YAML .yml files
7. Commit separately with clear message: docs: <description>

When in doubt:

• End-user visible → docs/user/
• API reference → docs/developer/api/
• Setup/onboarding → README.md
• Development related → docs/contributing/

Process & Continuity

• ✅ If mid-task and receive "no response", continue the task
• ✅ Verify no regressions before modifying/removing code

---

🔧 TECHNICAL STANDARDS

Backend Stack

• Language: Go 1.25+
• Database: PostgreSQL 15+ with pgx v5 driver only
• Authentication: JWT tokens with bcrypt password hashing
• Architecture: Service layer pattern (handlers → services → database)

Frontend Stack

• Styling: TailwindCSS (no custom CSS)
• Language: TypeScript (no JavaScript)
• Templates: HTMX with server-side rendering
• Patterns: Procedural/imperative with functional techniques where helpful (no OOP)

Containerization

• Runtime: Podman (not Docker)
• Build: Existing Dockerfile and docker-compose.yml only
• No local builds allowed

---

🔄 ERROR RECOVERY PROTOCOL

When code modification mistakes occur (deleted wrong code, broke compilation, etc.):

Immediate Actions

1. STOP - Don't make more edits
2. ASSESS - What was deleted? Is it critical?
3. REVIEW - Run git diff to see exact changes
4. RESTORE - Choose appropriate recovery method:
   • Recent mistake: git checkout -- filename
   • Complex restoration: Use git show HEAD:filename to recover deleted code
   • Multiple files: git reset HEAD~1 (if safe)
5. VERIFY - Compile and test restored code
6. DOCUMENT - Note what went wrong for future reference

Recovery Examples

# Recover a deleted function from original file
git show HEAD:internal/handlers/auth.go | sed -n '70,275p' > recovery.txt

# Revert entire file to original state
git checkout HEAD -- internal/handlers/auth.go

# Use git stash to save current state before rollback
git stash push -m "Broken state before fix"
git checkout -- internal/handlers/auth.go

Prevention (Learn From Mistakes)

• Why did the mistake happen?
• Was it too-broad matching?
• Was it insufficient context reading?
• Was it cascading fix-up attempts?
• Update guidelines to prevent recurrence

---

📋 WORKFLOW CHECKLISTS

Before Making Frontend-Only Changes

• Identify if backend modification could make implementation simpler
• Plan to use existing API endpoints only
• If backend change seems necessary, prepare confirmation request:
  • Required change description
  • Why it would help
  • Impact analysis
  • Alternative approaches considered
• Plan git commit structure (multiple logical commits)
• Identify documentation location (see Documentation section):
  • User-facing feature → docs/user/
  • UI/workflow changes → docs/user/
  • Setup instructions → README.md

Before Making Full-Stack Changes

• Read current schema completely (if database changes)
• Identify all columns that must be preserved
• Plan exact changes needed
• Verify Podman will be used for builds
• Plan git commit structure (multiple logical commits)
• Identify documentation location:
  • API changes → docs/developer/api/<category>/
  • New endpoints → Create new .md file in docs/developer/api/
  • API behavior → Update existing docs/developer/api/ files
  • Breaking changes → Both README.md + relevant docs/
  • Bruno OpenCollection YAML .yml files → Update/create alongside API changes

During Schema Changes (Full-Stack Only)

• Read current schema completely
• Identify all columns that must be preserved
• Plan exact changes needed
• Set up verification step
• Make intended changes
• Immediately verify by reading back modified sections
• Confirm ALL expected columns are present
• Verify schema.sql, models.go, and queries.sql are in sync
• Update local database (choose ONE):
  • Option 1 - Recreate database (recommended, loses data):

    podman compose down -v  # Delete all volumes
    podman compose up -d    # Start with fresh schema
    

  • Option 2 - Manual SQL migration (preserves data):

    podman exec bookhoard_db psql -U postgres -d bookhoard -c "YOUR SQL HERE"
    

• Verify database has new schema (check column types, indexes, etc.)

After API Changes

• Create/update Bruno OpenCollection YAML requests
• Test with no user context
• Test with regular user context
• Test with admin context
• Verify backward compatibility

Before Committing

• Run verification script: bash scripts/verify-guidelines.sh
• Fix any errors - verification must pass (0 errors) to commit
• Note warnings - informational only, do not auto-fix
• Run tests: go test ./... -v
• Run lint/typecheck if available
• Ensure no secrets in changes
• Verify logical commit structure
• Update documentation (see Documentation section):
  • User-facing changes → docs/user/
  • API changes → docs/developer/api/ + Bruno OpenCollection YAML .yml 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
• Assess impact: What was deleted? Is it critical?
• Review git diff: See exact changes made
• Restore strategy:
  • If recent mistake: git checkout -- filename
  • If complex: Reconstruct from git diff using git show HEAD:filename
• Verify recovery: Compile and test restored code
• Document mistake: Note what went wrong for future reference

Phase Completion Verification (Before Declaring "Complete")

• All target code is removed/intact as intended
• No unintended code was deleted
• All affected files compile successfully
• Run go build ./... for entire project
• Run verification script: bash scripts/verify-guidelines.sh - must pass (0 errors)
• No critical functionality was broken
• Git diff shows only intended changes
• Review all modified files with git diff --stat

---

🏗 ARCHITECTURAL PATTERNS

Current: Hybrid SSR

Browser → Go template (with data) → Display instantly
                    ↓
          JavaScript for interactivity (CRUD)
                    ↓
               Shared service layer

Ultimately, whenever you are unsure just ask for confirmation.