agent-core

A shared governance profile for Specsmith agents. It defines required checks, permissions, execution rules, and links between requirements, tests, and code changes.

In plain words
What is it for?
Use it when setting up or governing agents that need preflight checks, controlled permissions, context limits, testing traceability, and related safeguards.
Why use it?
It gives agents a consistent set of safety and tracking rules instead of leaving those decisions to each task.

Skill for Claude CodeCodex

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/layer1labs/specsmith/agent-core
Any agent
npx skills add layer1labs/specsmith --skill agent-core
Clone the repo
git clone --depth 1 https://github.com/layer1labs/specsmith

Made for: Claude Code, Codex.

Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 624 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 $0.00000 $0.00624
Opus 5 $0.00000 $0.00312
Sonnet 5 $0.00000 $0.00125
Haiku 4.5 $0.00000 $0.00062

Measured 2d ago against content hash cfa2e0c9607b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

agent-core 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 2d ago.

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.

.agents/skills/agent-core/SKILL.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL.md

Agent Core Profile

Requirements Covered

Governance Requirements

  • REQ-012: Least-Privilege Agent Permissions
  • REQ-217: Agent Permissions Check
  • REQ-220: Policy Guardrails
  • REQ-244: Context Window Sizing
  • REQ-245: Live Context Fill Indicator
  • REQ-246: Auto Context Compression
  • REQ-247: Hard Context Ceiling

Core Principle

The agent-core profile defines the fundamental capabilities and governance rules that all Specsmith agents must follow. This profile ensures that agents operate within the bounds of the Specsmith governance framework while maintaining the flexibility to adapt to different project contexts.

Profile Characteristics

Minimal Required Skills

  • preflight-gate
  • governed-agent-loop
  • requirement-author
  • testcase-author
  • traceability-auditor
  • context-pack-compiler
  • token-budget-auditor
  • skill-composer

Governance Compliance

All agents using this profile must:

  1. Run preflight checks before any action that could have side effects
  2. Follow the governed-agent-loop execution pattern
  3. Maintain traceability between requirements, tests, and code changes
  4. Compose skills dynamically based on context
  5. Track token usage and budget efficiency

Implementation Details

Core Loop Execution

  1. Detect Specsmith project context
  2. Run session bootstrap procedures
  3. Emit governance anchor
  4. Classify user intent (read-only, change, release, destructive, research, planning)
  5. For non-read-only actions, run preflight
  6. Load only required context and skills
  7. Execute smallest scoped action
  8. Run verification gates
  9. Record evidence
  10. Save through Specsmith

Context Management

  • Build minimal context packs from project state, requirements, work items, ESDB records, and relevant skills
  • Never inject the whole repository when a scoped context is sufficient
  • Prefer requirement IDs, test IDs, recent WIs, and relevant files
  • Exclude stale, low-confidence, tombstoned, or contradicted ESDB records
  • Include stop conditions and known hazards
  • Track token budget and context utilization

Read the full file on GitHub · 85 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. 2d ago First seen · 85 lines · 0 tokens per session scan A cfa2e0c9607b

Subscribe to this mod's changes

agent-core is a skill published in the GitHub repository layer1labs/specsmith (7 stars, last pushed 29d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 624 tokens. 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.

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