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testland/manifest-v3-test-surface-reference

Pure-reference catalog of the Manifest V3 test surface for Firefox + Chromium browser extensions. Maps each manifest field that changed from MV2 (manifest_version, background.service_worker vs background.scripts, action vs browser_action / page_action, host_permissions split, web_accessible_resources object-form, content_security_policy object-form), the runtime restrictions service workers impose (no DOM, no XMLHttpRequest, no localStorage, ephemeral lifecycle, synchronous listener registration, alarms instead of setTimeout), and the Firefox-vs-Chrome key matrix (browser_specific_settings.gecko, externally_connectable / offline_enabled gaps, MV2-only user_scripts manifest key); references/ carry Mozilla's web-ext CLI (lint via addons-linter, run on firefox-desktop / firefox-android / chromium targets, deterministic build, AMO sign). Use as the manifest-surface reference when authoring extension tests across both browsers, or when driving Firefox runs / AMO signing with web-ext.

69

Quality

87%

Does it follow best practices?

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SecuritybySnyk

Passed

No findings from the security scan

Overview
Quality
Evals
Security
Files

Quality

Content

78%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 well-structured reference skill: lean, table-driven, assumes competence, and cleanly splits bulk detail into two real one-level-deep reference files. It would benefit from a short explicit procedure for how to consume the reference and from trimming the few repeated table cells.

Suggestions

Add a brief 'How to use this reference' procedure (e.g. 1. consult the MV2/MV3 table, 2. cross-check the Firefox column in references/manifest-matrix.md, 3. drive Firefox runs/signing via references/web-ext-firefox.md) to raise workflow clarity.

Trim repeated context in the anti-patterns table and consolidate the keep-alive/offscreen mentions that recur across sections to tighten conciseness.

Move the version-sensitive 'MV3 platform availability' and MV2-deprecation timeline notes into a dedicated 'Version-sensitive details' subsection so time-sensitive content does not dilute the stable reference.

DimensionReasoningScore

Conciseness

Dense, table-driven body that assumes Claude knows MV3/manifests/service workers — no padding explaining basics — with only minor over-explanation in a few repeated table cells and the live-read MV2-deprecation note.

4 / 5

Actionability

Concrete and specific throughout — exact field shapes (e.g. { "service_worker": "sw.js", "type": "module"? }), exact APIs (chrome.offscreen.createDocument, chrome.alarms.create), exact URLs to fetch, and copy-pasteable test implications; falls just short of fully executable recipes because it is a reference, not a code skill.

4 / 5

Workflow Clarity

As a single-purpose reference catalog there is no destructive/batch operation to validate, and content is clearly organized with a 'When to use' section and per-field test implications; lacks an explicit step-by-step procedure for consuming the reference, so it stops short of 5.

4 / 5

Progressive Disclosure

Clear overview in SKILL.md with well-signaled, one-level-deep references to references/manifest-matrix.md and references/web-ext-firefox.md (both present), keeping summary tables inline while pushing the full 23-key matrix, offscreen/keepalive detail, and the web-ext CLI into separate files for easy navigation.

5 / 5

Total

17

/

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 precise, third-person reference description that clearly states both what it catalogs and when to reach for it, with concrete domain coverage and low overlap risk. Minor gains possible by adding Chrome-extensions and MV2-migration trigger synonyms.

DimensionReasoningScore

Specificity

Enumerates multiple concrete capabilities — mapping changed manifest fields (service_worker vs scripts, action vs browser_action, host_permissions split), runtime restrictions (no DOM/XHR/localStorage, ephemeral lifecycle, alarms), the Firefox-vs-Chrome key matrix, and the web-ext CLI surface — giving comprehensive coverage of the domain.

5 / 5

Completeness

Explicitly answers both 'what' (pure-reference catalog of the MV3 test surface: changed fields, runtime restrictions, key matrix, web-ext CLI) and 'when' ('Use as the manifest-surface reference when authoring extension tests across both browsers, or when driving Firefox runs / AMO signing with web-ext').

5 / 5

Trigger Term Quality

Strong natural terms a user would say — 'browser extensions', 'Manifest V3', 'Firefox + Chromium', 'extension tests', 'AMO signing', 'web-ext' — with the canonical 'Manifest V3' phrasing present; misses a few synonyms like an explicit 'Chrome extensions' trigger and MV2-migration phrasing.

4 / 5

Distinctiveness Conflict Risk

Occupies a clear niche — the MV3 manifest test surface across Firefox + Chromium — and explicitly contrasts itself against the sibling playwright-extension-fixtures skill, leaving minimal conflict risk.

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

metadata_version

'metadata.version' is missing

Warning

referenced_paths_exist

Referenced path issues: 3 missing

Warning

Total

14

/

16

Passed

Reviewed

Table of Contents

DiscoveryImplementationValidation