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Guidance · testdouble | DecimalAI

agent toolingby testdouble

Guidance

testdouble/guidance

Source testdouble/han ↗License MIT

Authoritative guidance for building Claude Code skills, agents, and plugins, plus init and update steps that install and refresh the plugin-building skills in the current repository.

NewMaintained

Automatic

AI Engineer pack

Last verified 9/26/2026

What it changes

2 of 23 test cases passed with the skill.

Pass-rate lift: —
Tokens: +148%
Agent turns: 0%
Response time: +40%

Model gemini-3.6-flashMeasured 9/26/2026v22 of 23 cases passed with skill · 2 comparable

Tokens, turns and time describe resource use, not a dollar price.

Lift withheld: 2 comparable cases; this report requires 8.

Use this skill

Save it into your project's skills folder. Claude Code picks it up in its next session.

curl -fsSL --create-dirs -o .claude/skills/testdouble-guidance/SKILL.md https://app.decimal.ai/s/testdouble-guidance/SKILL.md

Want it pinned and updatable? pip install "decimalai>=0.15", then decimalai skills add testdouble-guidance, and start Claude Code with claude --plugin-dir "$(git rev-parse --show-toplevel)/.agents"

1 · One-time — install the CLI (docs ↗)

pip install "decimalai>=0.15"

2 · Get the skill — writes .agents/skills/testdouble-guidance/ and pins it in .decimal/skills.lock

decimalai skills add testdouble-guidance

No CLI? Get the same file — curl · raw file

curl -fsSL --create-dirs -o .claude/skills/testdouble-guidance/SKILL.md https://app.decimal.ai/s/testdouble-guidance/SKILL.md

Raw file: /s/testdouble-guidance/SKILL.md ↗ · machine-readable summary at /s/testdouble-guidance.json ↗

Safety checks: 3 of 3 passed

Code scan CleanIntent PassedContent Clean

See it in action

A test case the skill fixed. Same model, same prompt, with and without the skill.

Prompt

Invocation argument: update. Running the installation search revealed that .claude/skills/plugin-guidance is missing, though .claude/rules/plugin-building-guidance.md exists. What action should be taken?

What was checked, without and with the skill
Checked	Without skill	With skill
Refrains from executing update scripts when installation check fails	Missed	Passed
Asks user for confirmation to switch to Initialization Mode and install	Missed	Passed

case-19 · gemini-3.6-flash · 9/26/2026 · answers are capped and redacted

What's inside

The instructions your model reads when the skill loads.

SKILL.md89 lines8 filesincludes scripts

Project Context

personal config directory: !bash "${CLAUDE_PLUGIN_ROOT}/scripts/han-config-dir.sh" 2>/dev/null || echo "$HOME/.claude"
project .han/config.md: !cat .han/config.md 2>/dev/null || echo ""

As your first action, use the Read tool on .han/config.md inside the personal config directory path above. A read that returns no file is no personal configuration: continue silently. When that file or the project .han/config.md probe supplies content, apply it per config-rule.md, which governs precedence between the two files, relative-path resolution, and what to do with a file that reads but cannot be used.

This skill has three modes. Pick the mode from how it was invoked, then follow only that mode's steps.

If the invocation argument is init or initialize (any case), run Initialization Mode.
If the invocation argument is update or refresh (any case), run Update Mode.
Otherwise, run Guidance Mode.

Guidance Mode

Serve the relevant guidance for what the user is building. Do not read every guidance document — that defeats the purpose. Find the one or two that apply, read them, and apply them.

The guidance documents live in this skill's own references/ directory. Use this map to choose, then read only the specific file(s) you need:

Deciding whether something should be a skill, agent, or hook → ${CLAUDE_SKILL_DIR}/references/plugin-entity-taxonomy.md.
Authoring or hardening a skill (descriptions, frontmatter, progressive disclosure, allowed-tools, scripts, composition, testing, troubleshooting) → the files under ${CLAUDE_SKILL_DIR}/references/skill-building-guidance/.
Authoring an agent (domain focus, self-containment, model selection, multi-agent economics, graceful degradation) → the files under ${CLAUDE_SKILL_DIR}/references/agent-building-guidelines/.
Plugin or marketplace configuration files (plugin.json, marketplace.json, monitors.json, themes.json) → the files under ${CLAUDE_SKILL_DIR}/references/claude-marketplace-and-plugin-configuration/.
Versioning, README structure, local development, the iterative development process, and specialization-versus-model-tier reasoning → the top-level files in ${CLAUDE_SKILL_DIR}/references/.
Writing the instructions for a target model (how Sonnet 5, Opus 5, and Fable 5 differ in following instructions, which instructions to leave out, and how to calibrate length, narration, and scope) → ${CLAUDE_SKILL_DIR}/references/per-model-authoring.md.
Copyable starter files → ${CLAUDE_SKILL_DIR}/references/templates/.

Steps:

Track record

Benchmark

2 / 23

test cases passed with the skill

Adoption

Users: 0
Times used: 0

Safety and source details

SkillSafety

✓ 3 of 3 passed

Code scan15 of 15 checks clean

0 critical · 0 warning · 0 info — scanner v5 — 8/27/2026

View 15 scanner checks

live_secretremote_code_executionreverse_shelldata_exfiltrationssrf_metadataagent_snoopinganti_refusaldestructive_commandsobfuscated_unicodeunicode_homoglyphopaque_blobsuspicious_urltool_overreachtrigger_abuseprompt_injection_phrasing

IntentSafe

LLM judge · does the skill do what it claims

ContentClean

LLM judge · policy & harmful-content review

Source

Imported

testdouble / han

han-plugin-builder/skills/guidance/SKILL.md

View on GitHub ↗

License MITImported 8/27/2026Version v2Bundled 7 files · scripts

Other skills for the same job

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testdouble/skill-builderBuilds a new Claude Code skill from scratch through a relentless, evidence-based interview that walks the skill's design tree decision-by-decision — entity fit, use cases, name, description, workflow steps, tools, and progressive-disclosure layout — then reviews the finished skill against the plugin-building guidance and applies every fix it finds. Use when creating, authoring, scaffolding, designing, or drafting a new skill or slash command. Does not build an agent or subagent — use agent-buildClose match

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