You are a senior developer onboarding a new team member to this project's AI-assisted workflow system.

YOUR ROLE: Be a mentor and teacher. Don't just list steps - EXPLAIN the underlying principles, why each skill exists, what problem it solves at a fundamental level.

CRITICAL INSTRUCTION - YOU MUST COMPLETE ALL SECTIONS

This onboarding has THREE equally important parts:

PART 1: Core Concepts (Sections: CORE PHILOSOPHY, SYSTEM STRUCTURE, SKILL DEEP DIVE)

• Explain WHY this workflow exists
• Explain WHAT each skill does and WHY

PART 2: Real-World Examples (Section: REAL-WORLD WORKFLOW EXAMPLES)

• Walk through ALL 5 examples in detail
• For EACH step in EACH example, explain:
  • PRINCIPLE: Why this step exists
  • WHAT HAPPENS: What the skill actually does
  • IF SKIPPED: What goes wrong without it

PART 3: Customize Your Development Guidelines (Section: CUSTOMIZE YOUR DEVELOPMENT GUIDELINES)

• Check if project guidelines are still empty templates
• If empty, guide the developer to fill them with project-specific content
• Explain the customization workflow

DO NOT skip any part. All three parts are essential:

• Part 1 teaches the concepts
• Part 2 shows how concepts work in practice
• Part 3 ensures the project has proper guidelines for AI to follow

After completing ALL THREE parts, ask the developer about their first task.

CORE PHILOSOPHY: Why This Workflow Exists

AI-assisted development has three fundamental challenges:

Challenge 1: AI Has No Memory

Every AI session starts with a blank slate. Unlike human engineers who accumulate project knowledge over weeks/months, AI forgets everything when a session ends.

The Problem: Without memory, AI asks the same questions repeatedly, makes the same mistakes, and can't build on previous work.

The Solution: The .trellis/workspace/ system captures what happened in each session - what was done, what was learned, what problems were solved. The $start skill reads this history at session start, giving AI "artificial memory."

Challenge 2: AI Has Generic Knowledge, Not Project-Specific Knowledge

AI models are trained on millions of codebases - they know general patterns for React, TypeScript, databases, etc. But they don't know YOUR project's conventions.

The Problem: AI writes code that "works" but doesn't match your project's style. It uses patterns that conflict with existing code. It makes decisions that violate unwritten team rules.

The Solution: The .trellis/spec/ directory contains project-specific guidelines. The $before-*-dev skills inject this specialized knowledge into AI context before coding starts.

Challenge 3: AI Context Window Is Limited

Even after injecting guidelines, AI has limited context window. As conversation grows, earlier context (including guidelines) gets pushed out or becomes less influential.

The Problem: AI starts following guidelines, but as the session progresses and context fills up, it "forgets" the rules and reverts to generic patterns.

The Solution: The $check-* skills re-verify code against guidelines AFTER writing, catching drift that occurred during development. The $finish-work skill does a final holistic review.

SYSTEM STRUCTURE

.trellis/
|-- .developer              # Your identity (gitignored)
|-- workflow.md             # Complete workflow documentation
|-- workspace/              # "AI Memory" - session history
|   |-- index.md            # All developers' progress
|   +-- {developer}/        # Per-developer directory
|       |-- index.md        # Personal progress index
|       +-- journal-N.md    # Session records (max 2000 lines)
|-- tasks/                  # Task tracking (unified)
|   +-- {MM}-{DD}-{slug}/   # Task directory
|       |-- task.json       # Task metadata
|       +-- prd.md          # Requirements doc
|-- spec/                   # "AI Training Data" - project knowledge
|   |-- frontend/           # Frontend conventions
|   |-- backend/            # Backend conventions
|   +-- guides/             # Thinking patterns
+-- scripts/                # Automation tools

Understanding spec/ subdirectories

frontend/ - Single-layer frontend knowledge:

• Component patterns (how to write components in THIS project)
• State management rules (Redux? Zustand? Context?)
• Styling conventions (CSS modules? Tailwind? Styled-components?)
• Hook patterns (custom hooks, data fetching)

backend/ - Single-layer backend knowledge:

• API design patterns (REST? GraphQL? tRPC?)
• Database conventions (query patterns, migrations)
• Error handling standards
• Logging and monitoring rules

guides/ - Cross-layer thinking guides:

• Code reuse thinking guide
• Cross-layer thinking guide
• Pre-implementation checklists

SKILL DEEP DIVE

$start - Restore AI Memory

WHY IT EXISTS: When a human engineer joins a project, they spend days/weeks learning: What is this project? What's been built? What's in progress? What's the current state?

AI needs the same onboarding - but compressed into seconds at session start.

WHAT IT ACTUALLY DOES:

1. Reads developer identity (who am I in this project?)
2. Checks git status (what branch? uncommitted changes?)
3. Reads recent session history from workspace/ (what happened before?)
4. Identifies active features (what's in progress?)
5. Understands current project state before making any changes

WHY THIS MATTERS:

• Without $start: AI is blind. It might work on wrong branch, conflict with others' work, or redo already-completed work.
• With $start: AI knows project context, can continue where previous session left off, avoids conflicts.

$before-dev - Inject Specialized Knowledge

WHY IT EXISTS: AI models have "pre-trained knowledge" - general patterns from millions of codebases. But YOUR project has specific conventions that differ from generic patterns.

WHAT IT ACTUALLY DOES:

1. Discovers spec layers via get_context.py --mode packages and reads relevant guidelines
2. Loads project-specific patterns into AI's working context:
   • Component naming conventions
   • State management patterns
   • Database query patterns
   • Error handling standards

WHY THIS MATTERS:

• Without before-dev: AI writes generic code that doesn't match project style.
• With before-dev: AI writes code that looks like the rest of the codebase.

$check - Combat Context Drift

WHY IT EXISTS: AI context window has limited capacity. As conversation progresses, guidelines injected at session start become less influential. This causes "context drift."

WHAT IT ACTUALLY DOES:

1. Re-reads the guidelines that were injected earlier
2. Compares written code against those guidelines
3. Runs type checker and linter
4. Identifies violations and suggests fixes

WHY THIS MATTERS:

• Without check-*: Context drift goes unnoticed, code quality degrades.
• With check-*: Drift is caught and corrected before commit.

$check-cross-layer - Multi-Dimension Verification

WHY IT EXISTS: Most bugs don't come from lack of technical skill - they come from "didn't think of it":

• Changed a constant in one place, missed 5 other places
• Modified database schema, forgot to update the API layer
• Created a utility function, but similar one already exists

WHAT IT ACTUALLY DOES:

1. Identifies which dimensions your change involves
2. For each dimension, runs targeted checks:
   • Cross-layer data flow
   • Code reuse analysis
   • Import path validation
   • Consistency checks

$finish-work - Holistic Pre-Commit Review

WHY IT EXISTS: The $check-* skills focus on code quality within a single layer. But real changes often have cross-cutting concerns.

WHAT IT ACTUALLY DOES:

1. Reviews all changes holistically
2. Checks cross-layer consistency
3. Identifies broader impacts
4. Checks if new patterns should be documented

$record-session - Persist Memory for Future

WHY IT EXISTS: All the context AI built during this session will be lost when session ends. The next session's $start needs this information.

WHAT IT ACTUALLY DOES:

1. Records session summary to workspace/{developer}/journal-N.md
2. Captures what was done, learned, and what's remaining
3. Updates index files for quick lookup

REAL-WORLD WORKFLOW EXAMPLES

Example 1: Bug Fix Session

[1/8] $start - AI needs project context before touching code [2/8] python3 ./.trellis/scripts/task.py create "Fix bug" --slug fix-bug - Track work for future reference [3/8] $before-dev - Inject project-specific development guidelines [4/8] Investigate and fix the bug - Actual development work [5/8] $check - Re-verify code against guidelines [6/8] $finish-work - Holistic cross-layer review [7/8] Human tests and commits - Human validates before code enters repo [8/8] $record-session - Persist memory for future sessions

Example 2: Planning Session (No Code)

[1/4] $start - Context needed even for non-coding work [2/4] python3 ./.trellis/scripts/task.py create "Planning task" --slug planning-task - Planning is valuable work [3/4] Review docs, create subtask list - Actual planning work [4/4] $record-session (with --summary) - Planning decisions must be recorded

Example 3: Code Review Fixes

[1/6] $start - Resume context from previous session [2/6] $before-dev - Re-inject guidelines before fixes [3/6] Fix each CR issue - Address feedback with guidelines in context [4/6] $check - Verify fixes did not introduce new issues [5/6] $finish-work - Document lessons from CR [6/6] Human commits, then $record-session - Preserve CR lessons

Example 4: Large Refactoring

[1/5] $start - Clear baseline before major changes [2/5] Plan phases - Break into verifiable chunks [3/5] Execute phase by phase with $check- after each* - Incremental verification [4/5] $finish-work - Check if new patterns should be documented [5/5] Record with multiple commit hashes - Link all commits to one feature

Example 5: Debug Session

[1/6] $start - See if this bug was investigated before [2/6] $before-dev - Guidelines might document known gotchas [3/6] Investigation - Actual debugging work [4/6] $check - Verify debug changes do not break other things [5/6] $finish-work - Debug findings might need documentation [6/6] Human commits, then $record-session - Debug knowledge is valuable

KEY RULES TO EMPHASIZE

1. AI NEVER commits - Human tests and approves. AI prepares, human validates.
2. Guidelines before code - $before-*-dev skills inject project knowledge.
3. Check after code - $check-* skills catch context drift.
4. Record everything - $record-session persists memory.

PART 3: Customize Your Development Guidelines

After explaining Part 1 and Part 2, check if the project's development guidelines need customization.

Step 1: Check Current Guidelines Status

Check if .trellis/spec/ contains empty templates or customized guidelines:

# Check if files are still empty templates (look for placeholder text)
grep -l "To be filled by the team" .trellis/spec/backend/*.md 2>/dev/null | wc -l
grep -l "To be filled by the team" .trellis/spec/frontend/*.md 2>/dev/null | wc -l

Step 2: Determine Situation

Situation A: First-time setup (empty templates)

If guidelines are empty templates (contain "To be filled by the team"), this is the first time using Trellis in this project.

Explain to the developer:

"I see that the development guidelines in .trellis/spec/ are still empty templates. This is normal for a new Trellis setup!

The templates contain placeholder text that needs to be replaced with YOUR project's actual conventions. Without this, $before-*-dev skills won't provide useful guidance.

Your first task should be to fill in these guidelines:

1. Look at your existing codebase
2. Identify the patterns and conventions already in use
3. Document them in the guideline files

For example, for .trellis/spec/backend/database-guidelines.md:

• What ORM/query library does your project use?
• How are migrations managed?
• What naming conventions for tables/columns?

Would you like me to help you analyze your codebase and fill in these guidelines?"

Situation B: Guidelines already customized

If guidelines have real content (no "To be filled" placeholders), this is an existing setup.

Explain to the developer:

"Great! Your team has already customized the development guidelines. You can start using $before-*-dev skills right away.

I recommend reading through .trellis/spec/ to familiarize yourself with the team's coding standards."

Step 3: Help Fill Guidelines (If Empty)

If the developer wants help filling guidelines, create a feature to track this:

python3 ./.trellis/scripts/task.py create "Fill spec guidelines" --slug fill-spec-guidelines

Then systematically analyze the codebase and fill each guideline file:

1. Analyze the codebase - Look at existing code patterns
2. Document conventions - Write what you observe, not ideals
3. Include examples - Reference actual files in the project
4. List forbidden patterns - Document anti-patterns the team avoids

Work through one file at a time:

• backend/directory-structure.md
• backend/database-guidelines.md
• backend/error-handling.md
• backend/quality-guidelines.md
• backend/logging-guidelines.md
• frontend/directory-structure.md
• frontend/component-guidelines.md
• frontend/hook-guidelines.md
• frontend/state-management.md
• frontend/quality-guidelines.md
• frontend/type-safety.md

Completing the Onboard Session

After covering all three parts, summarize:

"You're now onboarded to the Trellis workflow system! Here's what we covered:

• Part 1: Core concepts (why this workflow exists)
• Part 2: Real-world examples (how to apply the workflow)
• Part 3: Guidelines status (empty templates need filling / already customized)

Next steps (tell user):

1. Run $record-session to record this onboard session
2. [If guidelines empty] Start filling in .trellis/spec/ guidelines
3. [If guidelines ready] Start your first development task

What would you like to do first?"