apex

A development method that structures work into Analyze, Plan, Execute, eLicit, and eXamine phases. It requires codebase research, planning, self-review, and validation checks.

In plain words
What is it for?
Use it to guide substantial software changes from codebase exploration through implementation, testing, and review.
Why use it?
It reduces mistakes caused by incomplete understanding or untested assumptions. The process identifies affected components, edge cases, dependencies, and relevant tests before implementation.

Command

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/fusengine/agents/apex
Clone the repo
git clone --depth 1 https://github.com/fusengine/agents
Per session 42 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,578 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00042 $0.01578
Opus 5 $0.00021 $0.00789
Sonnet 5 $0.00008 $0.00316
Haiku 4.5 $0.00004 $0.00158

Measured yesterday against content hash 8cd0d3c1f5a9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

apex scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/ai-pilot/commands/apex.md · 208 lines

How it starts

The opening of the file, as written. The whole thing — 208 lines — stays where its author put it; the contents beside it link to each section on GitHub.

APEX: Analyze-Plan-Execute-eLicit-eXamine

Execute the comprehensive APEX methodology for professional-grade development.

Complete documentation: skills/apex-methodology/SKILL.md


Phase 1: ANALYZE (Deep Exploration)

Use explore-codebase to understand relevant parts of the system

Goals:

  • Identify where changes need to be made
  • Understand existing patterns and conventions
  • Map dependencies and impacts
  • Locate relevant tests

Deliverable: Exploration summary with affected components


Phase 2: PLAN (Strategic Design)

Use research-expert to validate approach against best practices

Goals:

  • Design solution following project patterns
  • Identify edge cases and error handling
  • Plan test strategy
  • Estimate impact and complexity

Deliverable: Implementation plan with step-by-step approach

Plan Format:

### Implementation Steps
1. [Component A]: [Required changes]
2. [Component B]: [Required changes]
3. [Tests]: [Test cases to add]

### Edge Cases
- [Case 1]: [Handling approach]
- [Case 2]: [Handling approach]

### Testing Strategy
- Unit tests: [What to test]
- Integration tests: [Scenarios]
- Manual testing: [Steps]

Phase 3: EXECUTE (Precise Implementation)

Implement the solution:

  1. Follow the plan step-by-step
  2. Maintain existing code style and patterns
  3. Add inline documentation for complex logic
  4. Create/update tests alongside code

Quality Standards:

  • SOLID principles without exception
  • DRY, KISS, YAGNI
  • Max 100 lines per file
  • Separate types/interfaces
  • Security validation (OWASP Top 10)

Phase 3.5: eLICIT (Self-Review) - NEW

Expert agent self-reviews and self-corrects before sniper validation

Modes:

  • --auto: Auto-select techniques based on code type (default)
  • --manual: Present 5 techniques, user chooses
  • --skip-elicit: Skip directly to eXamine

Workflow:

┌─────────────────────────────────────────────────────────┐
│  ELICIT (6 steps)                                       │
│                                                         │
│  Init → Analyze → Select → Apply → Correct → Report    │
│                                                         │
│  Expert applies elicitation techniques from 12 cats:   │
│  - Security (7)      - Performance (6)                 │
│  - Architecture (6)  - Testing (6)                     │
│  - Documentation (6) - UX/a11y (6)                     │
│  - Data (6)          - Concurrency (6)                 │
│  - Integration (7)   - Observability (6)               │
│  - Code Quality (7)  - Maintainability (6)             │
│                                                         │
│  Total: 75 techniques                                   │
└─────────────────────────────────────────────────────────┘

Read the full file on GitHub · 208 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 208 lines · 42 tokens per session scan A 8cd0d3c1f5a9

Subscribe to this mod's changes

apex is a command published in the GitHub repository fusengine/agents (25 stars, last pushed 28d ago), licensed MIT. It adds 42 tokens to every session and 1,578 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.