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isolating-product-facade-contracts

Plan and execute product isolation migrations to a facade plus contract layer in PostHog, following the Visual review architecture. Use when a product still exposes internals (models/logic/views) across boundaries and needs migration toward contracts.py + facade/api.py + presentation separation, with a PR strategy that minimizes review latency and conflicts with parallel work.

72

Quality

91%

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The risk profile of this skill

SKILL.md
Quality
Evals
Security

Quality

Content

88%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

A dense, expert-level migration playbook with copy-paste-ready commands, a clearly sequenced workflow with explicit validation gates, and well-signaled external references. Its main weakness is length: the file inlines reference-grade detail that could live in separate files, and repeats its core soundness argument in several places.

Suggestions

Split the 'Clearing coupling the scan won't show' taxonomy and the permanent-interface exception into a separate references file (e.g. COUPLING-CASES.md) and summarize the move-per-kind table in SKILL.md, keeping the body an overview.

Consolidate the ignore_imports-gates-the-skip soundness argument into one place (e.g. step 5) and reference it from step 6, the presentation wave, and the done criteria instead of restating it each time.

Extract the PR-strategy and presentation-wave sections into their own reference files, leaving SKILL.md to point to them, to bring progressive disclosure closer to a clean overview-plus-references structure.

DimensionReasoningScore

Conciseness

Information-dense and assumes Claude's intelligence (no explaining what a facade/serializer/tach is), with nearly every sentence carrying actionable or structural content; held below 5 by overall length and some repetition of the ignore_imports-gates-the-skip soundness argument across step 5, step 6, the presentation wave, and the done criteria.

4 / 5

Actionability

Fully executable guidance — copy-paste-ready commands (hogli product:isolate:scan/move, product:crossings --all --write-baseline), exact file paths (backend/facade/contracts.py, tach.toml, pyproject.toml TODO section), concrete code patterns (pydantic.dataclasses.dataclass, related_name="+", # isolation:permanent-interface), and named worked examples covering common cases.

5 / 5

Workflow Clarity

A clearly sequenced 6-step migration workflow with explicit validation checkpoints (product:lint fails if any chain step is skipped, blocks backend:contract-check while ignore_imports entries remain), error-recovery feedback loops (regenerate-on-conflict instead of hand-resolve), and a final done-criteria checklist — satisfying the batch/destructive validation requirement.

5 / 5

Progressive Disclosure

Good section structure and well-signaled one-level-deep external references (Core docs to load first, the Visual review reference implementation), with no bundle files present; held below 5 because substantial reference-grade material (the coupling-clearing taxonomy, permanent-interface exception, PR-strategy detail) is inlined in one ~570-line file rather than split into separate reference files.

4 / 5

Total

18

/

20

Passed

Description

92%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A highly specific, complete description that concretely states both the capability and the use-when trigger with named artifacts. The only minor gap is trigger-term breadth: the vocabulary is specialized internal jargon rather than a wide spread of synonyms a user might naturally say.

DimensionReasoningScore

Specificity

Lists multiple specific concrete actions — "Plan and execute product isolation migrations to a facade plus contract layer", "migration toward contracts.py + facade/api.py + presentation separation", and "a PR strategy that minimizes review latency and conflicts" — with named artifacts giving comprehensive coverage.

5 / 5

Completeness

Explicitly answers both what ("Plan and execute product isolation migrations to a facade plus contract layer...with a PR strategy...") and when ("Use when a product still exposes internals (models/logic/views) across boundaries and needs migration...") with concrete trigger phrases.

5 / 5

Trigger Term Quality

Good keyword coverage with natural phrasing a user would say ("isolate a product", "facade/contracts", "exposes internals across boundaries"), but the terms are specialized internal jargon rather than a broad spread of synonyms, so a few natural variations are missing.

4 / 5

Distinctiveness Conflict Risk

A clear niche — PostHog product-isolation migrations to a facade/contract layer following the Visual review architecture — with distinct triggers and minimal risk of firing for an unrelated skill.

5 / 5

Total

19

/

20

Passed

Validation

87%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 14 / 16 Passed

Validation for skill structure

CriteriaDescriptionResult

skill_md_line_count

SKILL.md is long (570 lines); consider splitting into references/ and linking

Warning

relative_links

Relative link issues: 15 suspicious

Warning

Total

14

/

16

Passed

Repository

PostHog/posthog

Path

.agents/skills/isolating-product-facade-contracts/SKILL.md

Reviewed

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