02 Coding Guidelines

Coding Guidelines Skill

Use When

• Produce or update project coding guidelines from approved project evidence.
• Resolve decisions about language and framework conventions, enforceable checks, examples, and exceptions.
• Prepare a reviewable handoff for Developers and reviewers.

Do Not Use When

• The task is primarily owned by technical-specification; route there and use this skill only for its named output.
• Required project evidence or decision authority is unavailable and the requester expects a pass, release, certification, or production change.

Required Inputs

Outputs

Evidence Produced

Capability and Permission Boundaries

• Minimum capabilities: read and search the authorised project sources. Execution is optional and limited to non-destructive validation.
• Assessment and planning default to read-only. Create or edit the named project document only when the request explicitly authorises it. Production mutation, publishing, destructive action, spending, external communication, or certification claims require separate explicit authority.
• Treat secrets, tenant data, incident evidence, and financial records as least-privilege inputs; expose only the minimum evidence needed for review.

Degraded Mode

If files, execution, network, rendering, environment access, fonts, or current evidence are unavailable, return the narrowest useful draft plus a gap register. Label affected checks not assessed, retain the intended acceptance oracle, and state who must supply or verify the missing evidence. Never convert an unavailable check into a pass.

Decision Rules

Workflow

1. Confirm the named deliverable, consumer, scope, environment, authority, and neighbouring-skill boundary.
2. Inventory required sources and validate provenance, freshness, internal consistency, and missing inputs. Stop the affected branch on a mandatory gap.
3. Extract traceable requirements, invariants, risks, and measurable acceptance criteria; record conflicts before choosing a design or procedure.
4. Apply the decision rules and the domain workflow below. For a failed branch, preserve evidence, choose the documented recovery path, or escalate to the named owner.
5. Draft the artefact, decision register, and evidence record together. Do not defer failure handling, rollback, security, tenancy, accessibility, or operational ownership.
6. Run available checks, review every result, repair failures, and hand off only when acceptance is observable. If recovery fails or authority is exceeded, stop and escalate without mutation.

Quality Standards

• Ground every section in a named project source, decision, measured result, or accountable owner.
• Give each requirement or procedure a deterministic oracle that another reviewer can reproduce.
• Keep assumptions, exclusions, degraded checks, residual risks, and waivers visible at handoff.
• Preserve the domain invariants and more specific controls in the existing workflow below; this contract does not replace them.
• Run the repository anti-AI-slop gate: remove filler, verify named standards and dependencies, and retain purposeful domain detail.

Anti-Patterns

• Copying a generic template without mapping it to project sources. Fix: attach each section to an approved requirement, configuration, risk, or owner.
• Choosing a threshold because it is common practice. Fix: derive it from a requirement, measured baseline, risk decision, or current verified source.
• Reporting an inaccessible or unexecuted check as passed. Fix: mark it not assessed, preserve the oracle, and name the verifier.
• Mixing the neighbouring technical-specification concern into this artefact without a boundary. Fix: cross-reference its output and keep ownership explicit.
• Omitting failure, rollback, empty-state, security, tenancy, or escalation behaviour. Fix: specify the trigger, safe action, verification, and owner for each applicable case.
• Mutating a repository, environment, tenant, ledger, or external system while drafting guidance. Fix: remain read-only until the exact mutation and authority are explicit.
• Claiming compliance, certification, readiness, or release from prose alone. Fix: require source-attributed evidence and a named acceptance decision.

Worked Example

Given an approved project source and a conflicting implementation detail, record both with provenance, stop the affected branch, and obtain the accountable owner's decision. Then update the relevant contract, define a reproducible acceptance check, and retain its observed result. The artefact is accepted only when every mandatory rule maps to a configured check or an explicit review step, with project-language examples.

References

• logic.prompt - load only when its template, logic, or detail is needed.
• README.md - load only when its template, logic, or detail is needed.

SaaS mode: if the project is a multi-tenant SaaS, apply references/saas-multi-tenant-coding-guidelines-addendum.md in addition to the generic steps below.

Overview

This is the second skill in Phase 04 (Development Artifacts). It generates language-specific coding standards that establish naming conventions, code structure patterns, anti-patterns to avoid, error handling conventions, and code quality metrics. The output ensures consistent, maintainable code across the development team and conforms to IEEE 730 (Software Quality Assurance Plans).

When to Use

• After tech_stack.md exists in projects/<ProjectName>/_context/ with language and framework details.
• Optionally after HLD.md exists in projects/<ProjectName>/<phase>/<document>/ to align coding patterns with architectural decisions.
• Can run in parallel with 03-dev-environment-setup since they address independent concerns.

Quick Reference

Input Files

Output Files

Core Instructions

Follow these seven steps in order. Halt and notify the user if a required input file is missing.

Step 1: Read Context Files

Read tech_stack.md from projects/<ProjectName>/_context/. Optionally read HLD.md from projects/<ProjectName>/<phase>/<document>/. Log the absolute path of each file read. If tech_stack.md is missing, halt execution and report the gap.

Step 2: Define Naming Conventions

For each language and framework detected in tech_stack.md, define naming conventions:

• Files: naming pattern, casing (kebab-case, PascalCase, snake_case), suffix rules
• Classes/Components: casing, prefix/suffix conventions (e.g., Service, Controller, Repository)
• Functions/Methods: casing, verb-first naming (e.g., getUser, calculateTotal)
• Variables: casing, descriptive naming rules, abbreviation policy
• Database Columns: casing (snake_case), naming patterns for foreign keys, timestamps, and flags
• Constants: UPPER_SNAKE_CASE with grouping conventions

Step 3: Define Code Structure Patterns

Define the project directory layout and module organization:

• Top-level directory structure with purpose annotations
• Module boundary rules (what belongs in each layer)
• File length and function length guidelines with specific thresholds
• Import ordering conventions

Step 4: Define Anti-Patterns to Avoid

Document specific anti-patterns with explanations:

• Code smells to reject in code review (e.g., God classes, deep nesting, magic numbers)
• Framework-specific anti-patterns (e.g., direct DOM manipulation in React, N+1 queries in ORMs)
• Security anti-patterns (e.g., string concatenation for SQL, hardcoded credentials)

Step 5: Define Error Handling Conventions

Establish error handling standards:

• Exception hierarchy aligned with the LLD error handling design
• Try-catch scope rules (narrow catches, no empty catch blocks)
• Error message format standards (structured, loggable, user-safe)
• Async error handling patterns (Promise rejection, callback error-first)

Step 6: Define Logging and Debugging Standards

Establish logging conventions:

• Log levels (DEBUG, INFO, WARN, ERROR, FATAL) with usage criteria
• Structured log format (JSON with timestamp, level, correlation ID, message)
• Sensitive data redaction rules (mask PII, credentials, tokens)
• Debug tooling recommendations aligned with tech stack

Step 7: Write Output

Write the completed document to projects/<ProjectName>/<phase>/<document>/Coding_Guidelines.md. The document shall include a Code Review Checklist section that summarizes all conventions as a reviewable checklist. Log the total count of conventions defined.

Output Format

The generated Coding_Guidelines.md shall contain these sections in order: Document Header (project name, date, version, standard), 1. Naming Conventions, 2. Code Structure, 3. Design Patterns to Use, 4. Anti-Patterns to Avoid, 5. Error Handling, 6. Logging, 7. Security Practices, 8. Code Review Checklist.

Common Pitfalls

Verification Checklist

• Coding_Guidelines.md exists in projects/<ProjectName>/<phase>/<document>/ with all eight sections populated.
• Naming conventions cover files, classes, functions, variables, database columns, and constants.
• Anti-patterns include framework-specific items derived from tech_stack.md.
• Error handling conventions define an exception hierarchy and message format.
• Logging standards define structured format with redaction rules for sensitive data.
• Code Review Checklist summarizes all conventions as reviewable items.

Integration

Standards

• IEEE 730 -- Software Quality Assurance Plans. Governs the definition of coding standards and quality practices.

Resources

• logic.prompt -- Executable prompt containing the step-by-step coding guidelines generation logic.
• README.md -- Quick-start guide for this skill.