# Layer 1 Overview

> Layer 1 specializes the SDLC framework for a specific programming language. It inherits from Layer 0 and extends it with language-specific behavior only.

- Skill: `tools-only/layer-1-overview` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add tools-only/layer-1-overview`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tools-only/layer-1-overview/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tools-only (https://skillmd.com/u/tools-only)
- Updated: 2026-09-29
- Page: https://skillmd.com/skills/tools-only/layer-1-overview

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# Layer 1 Overview

Layer 1 specializes the SDLC framework for a specific programming language. It inherits from Layer 0 and extends it with language-specific behavior only.

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## Inheritance from Layer 0

**Layer 0 gates apply before role resolution.** Before the harness resolves language manifests:

1. RT-ICA prerequisite gate (AVAILABLE | DERIVABLE | MISSING)
2. Human touchpoint model (escalation triggers, loop limits)
3. Artifact conventions (ARTIFACT:{TYPE}({SCOPE}))
4. Verification protocol (producer vs evaluator, CERTIFIED/NOT_CERTIFIED)
5. Orchestrator discipline (delegation, no investigation escalation)

Language manifests **declare specialists and gates**. They do **not** redefine process.

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## Layer 1 ≠ Layer 0 Boundary

| Layer 0 (Do not duplicate) | Layer 1 (Extend only) |
|----------------------------|------------------------|
| SAM 7-stage pipeline | Process Flow Override (optional, rare) |
| Human touchpoint model | — |
| Artifact conventions | — |
| RT-ICA, verification | — |
| Task file format | — |
| Subagent contract | — |
| — | Role Fulfillment (architect, test-designer, etc.) |
| — | Quality Gates (format, lint, typecheck, test, standards) |
| — | Project Detection (markers, source/test patterns) |
| — | Conventions (naming, structure, testing, documentation) |
| — | Language standards (e.g., modernpython) |

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## CoVe Bypass Anti-Pattern

Orchestrators pass paths and outcomes; agents discover and verify. Do not pre-gather data for agents. Layer 1 skills must not instruct orchestrators to read source files for agents.

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## Non-Typed Languages

For languages without static typing (e.g., Bash, Perl without strict typing), use `typecheck: (none)` in Quality Gates. The harness skips the typecheck gate when `(none)` is declared.