Coder Add-Feature

Add a new feature to an EXISTING codebase using eri-coder workflow. Designed for brownfield development - modifying projects that already have code.

Dynamic Context

CLI analysis: !python3 -m erirpg.commands.add_feature $ARGUMENTS --json 2>/dev/null || echo '{"error": "CLI failed"}'

Codebase mapping status: !ls .planning/codebase/*.md 2>/dev/null | head -5 || echo "NOT_MAPPED"

Existing features: !ls -d .planning/features/*/ 2>/dev/null | head -5 || echo "none"

Two Modes

Standard Mode

Add new features to a codebase:

python3 -m erirpg.commands.add_feature "<feature-description>" --json

Reference Mode (Feature Porting)

Port a feature from another program using behavior specs:

python3 -m erirpg.commands.add_feature <target> <feature> "<desc>" --reference <source>/<section> --json

Example:

python3 -m erirpg.commands.add_feature eritrainer sana "Sana model" --reference onetrainer/models/sana --json

Prerequisites

1. •Must be in a project root (package.json, Cargo.toml, pyproject.toml, go.mod)
2. •Codebase should be mapped (auto-runs /coder:map-codebase if not)

Output Structure

.planning/features/{feature-name}/
├── SPEC.md      # Feature specification
├── CONTEXT.md   # Discussion decisions (optional)
├── RESEARCH.md  # Technical research (if needed)
├── PLAN-*.md    # Implementation plans
└── SUMMARY.md   # Completion summary

Workflow Steps

Step 1: Validate Environment

Check project root and codebase mapping status. See reference.md.

Step 2: Load Codebase Context

Read STACK.md, ARCHITECTURE.md, CONVENTIONS.md from .planning/codebase/. See reference.md.

Step 3: Feature Discussion

Ask clarifying questions with AskUserQuestion. See reference.md.

Step 4: Write Feature Spec

Create SPEC.md with problem, user stories, acceptance criteria. See reference.md.

Step 5: Context Discussion (Optional)

Discuss UI, API, or complex decisions if needed. See reference.md.

Step 6: Research Phase (If Needed)

Spawn eri-phase-researcher for non-trivial features. See reference.md.

Step 7: Create Implementation Plan

Spawn eri-planner with full context. See reference.md.

Step 8: Plan Verification

Spawn eri-plan-checker to verify coverage. See reference.md.

Step 9: Execute

Show summary, confirm with user, spawn eri-executor agents. See reference.md.

Step 10: Verification

Verify criteria met, create SUMMARY.md, commit. See reference.md.

Reference Mode Details

For porting features from another program, see reference.md.

Key insight: Behavior specs are portable, implementation details are not.

Agent Strategy

Key Principles

1. •ALWAYS respect existing codebase patterns
2. •NEVER create new patterns when existing ones work
3. •Read CONVENTIONS.md before writing ANY code
4. •Integrate at the RIGHT place (check ARCHITECTURE.md)
5. •Update existing tests if modifying tested code

Completion

Use templates/completion-box.md format.