An engineering agent with separate modes for planning file changes, implementing approved work, and reviewing the complete code change.

Use it to propose implementation work, build from engineering tickets, or perform an adversarial review of a branch or working diff.

It separates deciding what to change, writing the code, and looking for problems in the finished change.

eng — Skill by ndisisnd

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 skills/ndisisnd/msg/eng

Any agent

npx skills add ndisisnd/msg --skill eng

Clone the repo

git clone --depth 1 https://github.com/ndisisnd/msg

Made for: Claude Code, Codex.

Per session 130 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,656 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.

Model	Per session	Once invoked
Fable 5	$0.00130	$0.01656
Opus 5	$0.00065	$0.00828
Sonnet 5	$0.00026	$0.00331
Haiku 4.5	$0.00013	$0.00166

Measured yesterday against content hash adb666015f72, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

eng 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.

.claude/skills/eng/SKILL.md · 63 lines

How it starts

The opening of the file, as written. The whole thing — 63 lines — stays where its author put it; the contents beside it link to each section on GitHub.

eng

Platform-agnostic engineering agent with three modes — --plan, --build, --review — each a distinct protocol in its own ref file, selected by the invocation flag. This file routes; the shared spine that runs for every mode is refs/protocol-core.md (Steps 0–6), and it never runs a mode's work itself.

Routing (Step 0 — full rules in `refs/protocol-core.md`)

Read the invocation flag and load exactly one mode protocol:

Flag	Read
`--plan`	`refs/plan/protocol.md`
`--plan report=<path>`	`refs/plan/fix-plan.md` (instead of `protocol.md`)
`--build`	`refs/build/protocol.md` — unless an orchestrator spawned you as a build packet, in which case read `refs/build/protocol-packet.md` instead and stop; it is the whole leaf contract
`--build report=<path>`	`refs/build/fix-build.md` (instead of `protocol.md`)
`--review`	`refs/review/protocol.md`

Natural-language triggers for --review: "review this change", "review my diff", "code review this branch", "adversarial review", "look for bugs in what I just wrote". Anything asking for style, naming or standards is /cook, not this mode. --quiet / --status <n>m (--build only) — heartbeat control; flag beats policy beats default (../shared/refs/status-heartbeat.md).

Exactly one mode flag must be present — zero, several, or the retired --todo hard-fail with the exact messages in refs/protocol-core.md § Step 0. Then read the active mode file fully and run the spine end-to-end:

The shared spine (`refs/protocol-core.md`)

Step 1 — Input validation. PRD/exec-table source (mode flag + prd-path + rows + agent, hard-refuse on any missing) or the report=<path> alternate; more than one source is a hard failure. --review is exempt from Steps 1–4 — its input is the working diff; go straight to Step 5.
Step 2 — Pre-flight, one pass. Orchestrated fast path works from injected scoped excerpts (full PRD only as escape hatch); standalone path reads the full PRD, verifies row ownership mechanically via script-prd-digest.py --verify-rows, and reads devkit + the row-relevant codebase in parallel.
Step 3 — Summary + approval gate. 3–4 line summary, then AskUserQuestion (Yes / needs correction / follow-up → the Step 3a interview). Never proceed without an explicit "Yes, proceed" (pre-approved under an autonomy contract).
Step 4 — Coding standards (--build only). Injected standards payload wins; else derive the /cook flag set and consult the persistent standards cache (script-standards-cache.py) before calling /cook (v5.6.5; ../shared/refs/session-cache.md § Consumers).
Step 5 — Run the active mode's work per its ref, then the closing message (../shared/refs/closing-message.md) as the last chat output, doctor-logging harness incidents (../shared/refs/doctor-logging.md).
Step 6 — Scope enforcement, continuous. Only the assigned rows; unresolvable ambiguity is surfaced as a gap (plan/review) or blocks and asks (build) — never resolved by assumption.

Read the full file on GitHub · 63 lines

Files

What ships with it

11 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

yesterday First seen · 63 lines · 130 tokens per session scan A adb666015f72

Subscribe to this mod's changes

eng is a skill published in the GitHub repository ndisisnd/msg (6 stars, last pushed 15d ago), licensed MIT. It adds 130 tokens to every session and 1,656 once invoked, about $0.0006 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 2026-08-31.

Code review Git and workflow Planning agent-skills agentic-ai agentic-coding agentic-workflows agents claude-code

skillspec-migrate

Complete a .agent.partial file by resolving TODO markers.

e01n0/skillspec · 16 tokens

skill-writer

Review a SkillSpec .agent file for quality, correctness, and adherence to SkillSpec design principles.

e01n0/skillspec · 24 tokens

skillspec-test

Execute test blocks from a SkillSpec .agent file.

e01n0/skillspec · 15 tokens

skillspec-backport

Reconcile changes from a modified SKILL.md back into the .agent source file.

e01n0/skillspec · 22 tokens

git-commit-helper

Generate conventional commit messages automatically. Use when user runs git commit, stages changes, or asks for commit message help. Analyzes git diff to create clear, descriptive conventional commit messages. Triggers on git commit, staged changes, commit message requests.

alirezarezvani/claude-code-tresor · 55 tokens

code-reviewer

Automatic code quality and best practices analysis. Use proactively when files are modified, saved, or committed. Analyzes code style, patterns, potential bugs, and security basics. Triggers on file changes, git diff, code edits, quality mentions.

alirezarezvani/claude-code-tresor · 54 tokens