SP Engineering Cheat Sheet

Tactical Lookups · Quick Reference

The recipes, not the creed. Tape this next to your monitor. For the why behind any of these → Playbook.

Branching ↗

Format: <type>/SPPLT-XXXXX

feature/New capability

enhancement/Improve existing feature

bugfix/Prod bug

defect/In-sprint, pre-prod

hotfix/Urgent prod fix

techdebt/Debt repayment

maintenance/Short-lived cleanup

Commit: [SPPLT-XXXXX] message in English

PR Size Tiers ↗

Tier	LOC	Failure rate
Elite	< 225	< 1%
Good	225–370	1–4%
Fair	371–698	5–17%
Needs Focus	> 698	> 17%

90-min rule: if a reviewer can't finish in < 90 min, decompose first.

Endpoint Test Matrix ↗

200Success — happy path payload

401Unauthorized — no/invalid auth

403Forbidden — auth'd but no permission

422Validation — bad input rejected

Plus tests for any Actions, Jobs, Mailables, Notifications. System tests < 2s.

Decomposition Techniques ↗

SPIDR Slicing — Spike · Paths · Interface · Data · Rules
Hamburger Method — thinnest end-to-end slice first
Walking Skeleton — full path with stubs, fill in later
One Concern Rule — if you'd describe it with "and", split it

Code Review Lenses ↗

Pick 3–4. Each lens = focus + explicit exclusions.

Code	Correctness · Security · Maintainability
Architecture	Failure modes · Migration risk · Operational complexity
Config	Security · Blast radius · Drift

Output: Critical · Warnings · Suggestions. Pint owns formatting.

Bug Fix Workflow ↗

Reproduce — get it failing locally
Red — failing test for the right reason
Diagnose — Route → FormRequest → Controller → Service → Model
Green — minimal fix, run domain tests, check nearby

Don't refactor while fixing. Fix forward — no hotfix branches; flag if needed.

Common Bug Root Causes ↗

Missing eager loading (N+1) — esp. Library relationships
Wrong account scope, missing tenant filter
FormRequest authorize() gap
Race conditions on shared state
Type / null handling, implicit casts
Queue job timeouts / memory from loading too much

Feature Flag Stages ↗

Create — LaunchDarkly, camelCaseKey
Develop — wire with safe fallback
Test — local → preview → prod
Rollout — canary, then % of prod
Cleanup — the stage that gets skipped

Semantic Versioning ↗

	Platforms	Packages
MAJOR	Start of year	Breaking change
MINOR	End of sprint	BC feature
PATCH	Within sprint	Bug fix

Packages release: npm run release:patch|minor|major

Database Changes ↗

Schema change → Laravel migration (up() + down())
Prod data change → OneTimeOperation class
Modify column → repeat ALL attributes (else dropped)
OTO files → keep after running. Audit trail.
Never raw SQL against production

Backend Merge Gates ↗

1 approval
Passing tests + endpoint matrix
System tests < 2 seconds
./vendor/bin/pint --dirty before finalizing
New business logic → Service (not new Action)
New models → explicit $fillable
Auth: prefer $user->can() over hasRole()

Build vs. Adopt ↗

Default to adopt. Build only for differentiation.

70%+	of TCO is maintenance
40%	of IT budget is tech debt
35%	of large custom IT projects abandoned
4–5×	revenue growth, top-quartile dev velocity

Always document what you're choosing not to build.

Value Streams ↗

Product Streams

Library · Learning Experience · Organized Learning
Platform Access · VAR · Live-Training
Performance Management · Talent Marketplace

Capability Teams

Skills Validation · Core Platform Team · SP Admin

SPENG Confluence parent: page 2200535044. Use the /value-stream skill to load all pages.

Trio Decision Rights ↗

What problem	PM — business value
How to solve (UX)	Designer — UX integrity
How to build	Engineer — sustainability

Default: consensus through evidence. Unlock question: "What evidence would change your mind?"

Engineer-Mode Behaviors ↗

Boy Scout Rule — leave it cleaner than you found it
Beyoncé Rule — if you liked it, put a CI test on it
"What if we could…?" — expand the option space in discovery
"What evidence would change your mind?" — unlock stalled debate
Document non-builds — opportunity cost stays visible
1-on-1 question — "what did you make easier to change?"

Types of Work ↗

FeatureNew capability

EnhancementImprove existing

BugFound in production

DefectFound before production

Tech DebtQuality, no new user value

SpikeTime-boxed research → recommendation

SupportMigrations, conversions, localization

RewritePlanned redesign — Feature or Enhancement

Install Claude Skills ↗

User-level (recommended):

# Available in every working directory
git clone git@github.com:solidprofessorhub/sp-claude-skills.git \
  ~/.claude/skills/sp

Per-repo (locked version):

git submodule add \
  git@github.com:solidprofessorhub/sp-claude-skills.git \
  .claude/skills/sp