Harness Onboard

The session startup ritual. Every new agent session in a harness project starts here. Based on Anthropic's shift-handoff pattern: each new agent reads the shift notes left by the previous agent, verifies the environment, then picks up the next task.

First: Am I the Initializer or a Coding Agent?

This distinction matters. Anthropic's research found that the first session requires a fundamentally different prompt and task than all subsequent sessions.

# Check if this is the first session
if [ ! -f "claude-progress.txt" ] || ! grep -q "SESSION" claude-progress.txt; then
  echo "INITIALIZER MODE: No prior sessions detected"
else
  echo "CODING AGENT MODE: Prior sessions exist"
fi

If INITIALIZER (first session, no prior progress):

Your job is environment setup only — not feature implementation. Run /harness-engineer:init and follow the full scaffold workflow. Do NOT start implementing features. Do NOT touch application code. Your deliverables: AGENTS.md, features.json, init.sh, docs/, layers.json, claude-progress.txt. End by writing an initial progress entry and committing everything.

If CODING AGENT (subsequent sessions):

Follow the ritual below. Your job is incremental feature progress.

The Ritual (run in this exact order)

1. Orient (30 seconds)

# Where am I?
pwd
ls -la

# What's the recent history?
git log --oneline -10

# What was the last session working on?
tail -50 claude-progress.txt

# What's the current feature state?
python3 -c "
import json
with open('features.json') as f:
    data = json.load(f)
features = data if isinstance(data, list) else data.get('features', [])
passing = [f for f in features if f.get('passes') == True]
failing = [f for f in features if f.get('passes') == False and not f.get('circuit_broken')]
broken = [f for f in features if f.get('circuit_broken') == True]
in_prog = [f for f in features if f.get('in_progress') == True]
print(f'✓ Passing: {len(passing)} | ✗ Failing: {len(failing)} | ⚡ Broken: {len(broken)} | ⏳ In Progress: {len(in_prog)}')
print()
print('Next up (top 3 failing by priority):')
todo = sorted([f for f in failing], key=lambda x: x.get('priority', 99))[:3]
for f in todo:
    print(f'  [{f[\"id\"]}] {f[\"description\"][:80]}')
"

2. Verify Environment

# Start the dev server (this is mandatory — never skip)
bash init.sh

# If init.sh doesn't exist, find and start the dev server manually:
# node: npm run dev / npm start
# python: python manage.py runserver / uvicorn main:app
# etc.

If init.sh fails: STOP. Do not write code. Fix init.sh first. The dev server being broken is a P0 harness issue — report it and fix it before anything else.

3. Map the Environment (LangChain LocalContextMiddleware pattern)

# Directory structure
find . -type f -not -path '*/node_modules/*' -not -path '*/.git/*' -not -path '*/.harness/state/*' | head -60

# Available tools (language-specific)
which node python3 python go rust cargo 2>/dev/null
node --version 2>/dev/null; python3 --version 2>/dev/null

# Package info
cat package.json 2>/dev/null | python3 -c "import json,sys; d=json.load(sys.stdin); print('Scripts:', list(d.get('scripts',{}).keys()))" 2>/dev/null

4. Pick the Next Feature

import json

with open('features.json') as f:
    data = json.load(f)

features = data if isinstance(data, list) else data.get('features', [])

# Skip: passing, circuit_broken, in_progress (from other agents)
candidates = [
    f for f in features
    if not f.get('passes')
    and not f.get('circuit_broken')
    and not f.get('in_progress')
]

# Sort by priority (lower = higher priority)
candidates.sort(key=lambda x: x.get('priority', 99))

if candidates:
    next_feature = candidates[0]
    # Mark as in_progress to prevent other agents grabbing it
    next_feature['in_progress'] = True
    with open('features.json', 'w') as f:
        json.dump(data, f, indent=2)
    print(f"Working on: [{next_feature['id']}] {next_feature['description']}")
    print(f"Steps: {next_feature.get('steps', [])}")
else:
    print("🎉 All features passing! Run harness-gc to clean up.")

Also acquire a task lock for multi-agent setups:

# Claim the task lock (Anthropic C compiler pattern)
echo "$(date): session-$$" > current_tasks/[feature-id].txt

For complex features (3+ files, multiple sessions, or architectural decisions): Create an execution plan before writing any code:

# Copy the template and fill it in
cp .harness/../templates/execution-plan.md.template docs/plans/plan-[feature-id].md
# Fill in: feature spec, approach, files to change, layer analysis, risk assessment
# This becomes the working document for the feature — update it as you go

Add docs/plans/ to AGENTS.md repository map if not already present.

5. Apply the Reasoning Sandwich (LangChain pattern)

Structure your work in three phases with appropriate reasoning depth:

Phase 1 — Plan (xhigh reasoning):

Re-read the feature description and steps carefully
Read relevant existing code before touching anything
Write a brief plan: what files will change, what approach, what could go wrong
Verify your plan doesn't violate layers.json constraints

Phase 2 — Build (high reasoning):

Implement one step at a time
Before writing code, re-read the feature steps array — these are your acceptance criteria
Write code so a person executing those steps in a real browser will see the described behavior
Write tests as you go, not after — but remember: unit tests passing ≠ steps passing
Commit partial progress if you complete a logical sub-unit
Treat the steps array like a CI test suite written by a QA engineer: do not work around it

Phase 3 — Verify (xhigh reasoning):

Run the full test suite

Check browser automation availability first:

python3 -c "
import json
try:
    c = json.load(open('.harness/config.json'))
    ba = c.get('browser_automation', {})
    if ba.get('enabled'):
        print(f'BROWSER: {ba.get(\"mcp_server\",\"puppeteer\")} MCP available — USE IT for verification')
    else:
        print('BROWSER: disabled — verify manually by executing feature steps')
except: print('BROWSER: config not found — verify manually')
"

If browser automation enabled: use the configured MCP tool (e.g. Puppeteer) to navigate and execute each feature step in a real browser. This is the gold standard — Anthropic research shows it prevents premature completion better than any other technique.
If browser automation disabled: manually execute every step in the feature's steps array. Open the app, click through the flow. Do not read code to verify — observe behavior.
Compare result against original feature steps, not against your own code
Check browser console for errors (even if everything "looks right")
Only mark passes=true after all steps pass and console is clean

6. Session End Protocol

Before ending the session:

# 1. Final commit with descriptive message
git add -A
git commit -m "feat([feature-id]): [what was implemented]"

# 2. Release task lock
rm -f current_tasks/[feature-id].txt

# 3. Update progress file
cat >> claude-progress.txt << EOF

=== SESSION $(date '+%Y-%m-%d %H:%M') ===
Completed: [feature-id] — [description]
State: [passing/partial/abandoned and why]
Next session should: [specific instruction for next agent]
Known issues: [anything that might trip up the next agent]
Commits: $(git log --oneline -3)
===========================================
EOF

# 4. Update feature status
# Mark passes=true if done, in_progress=false in either case

Quick Reference Card

START:  pwd → git log → tail claude-progress.txt → python3 features.json summary
VERIFY: bash init.sh (MANDATORY — never skip)
MAP:    find . -type f (top 60) → check tools available
PICK:   features.json → sort by priority → mark in_progress=true → lock current_tasks/
BUILD:  Plan(xhigh) → Build(high) → Verify(xhigh)
TEST:   end-to-end as user, not just unit tests, check browser console
COMMIT: after every feature, descriptive message
END:    git commit → rm lock → update claude-progress.txt → update features.json

If You're Confused

Read these in order:

AGENTS.md — the map
claude-progress.txt — what the last agent did
git log --oneline -20 — what changed recently
features.json — what's left to do
docs/architecture.md — how the system is structured

If still confused: write a note in claude-progress.txt and start harness-doctor.