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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). Use as the manifest-surface reference when authoring extension tests across both browsers.

70

Quality

88%

Does it follow best practices?

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SecuritybySnyk

Passed

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Overview
Quality
Evals
Security
Files

Quality

Content

87%

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 body, concrete actionable test-authoring guidance, and textbook progressive disclosure into a single verified reference file. The only gap is workflow clarity — it is a lookup catalog, not a sequenced process with validation checkpoints.

Suggestions

Add a short explicit authoring workflow (e.g., 1. identify scenario in 'When to use,' 2. look up the field's test implication in the summary table, 3. pull the exact shape from references/manifest-matrix.md, 4. cross-check the Anti-patterns table) to give the lookup flow a clear sequence.

Include a validation checkpoint for the conformance path — e.g., 'assert manifest_version == 3 first, then per-field assertions' — so the implicit test-authoring flow has an explicit entry assertion.

Optionally add a minimal copy-paste manifest skeleton in the body (or a clearly signaled snippet in the reference) so a test author has a directly executable starting point without reassembling fields from the table.

DimensionReasoningScore

Conciseness

The body is lean and table-driven with purposeful framing (navigation pointers, distinctiveness vs sibling skills) rather than padding; it does not belabor concepts Claude already knows, so it matches the 'lean and efficient; every token earns its place' anchor.

3 / 3

Actionability

Provides concrete, specific directives — exact field names, conceptual shapes ("array of { resources: [...], matches: [...] } objects"), per-field test implications, and an anti-patterns table with precise fixes ("Use chrome.storage.local," "Register synchronously at top level"); as an instruction-only reference skill, code absence in the body is not penalized per the scoring note, with executable shapes appropriately deferred to the reference.

3 / 3

Workflow Clarity

Sections and tables are well-organized and support an implicit lookup flow (When-to-use → field table → reference), but there is no explicit multi-step sequence, validation checkpoint, or feedback loop, and the skill is too multi-faceted to qualify for the simple-skill auto-3; this fits 'sequence present but checkpoints missing or implicit' rather than the unclear level 1.

2 / 3

Progressive Disclosure

Clear overview with inline summary tables that repeatedly and explicitly signal one-level-deep detail in references/manifest-matrix.md (verified to exist), with exact shapes, the full key matrix, and code appropriately split out; matches the 'clear overview with well-signaled one-level-deep references' anchor.

3 / 3

Total

11

/

12

Passed

Description

85%

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 strong, highly specific description with explicit what-and-when trigger guidance and a clear, conflict-resistant niche. Its main weakness is trigger-term naturalness: real user keywords are diluted by dense manifest-field jargon and the less-natural 'Chromium' phrasing.

Suggestions

Lead with the natural user phrasings ('Manifest V3,' 'browser extension tests,' 'Firefox and Chrome') before the parenthetical field list so trigger terms are not buried under jargon.

Prefer 'Chrome' alongside or instead of 'Chromium' to match the term users most often say, and add common variations like 'web extension' or 'MV3 migration.'

Trim the parenthetical enumeration of field names to the few that most distinguish the skill, reducing verbosity without losing specificity.

DimensionReasoningScore

Specificity

Lists multiple concrete mapped items — "manifest_version, background.service_worker vs background.scripts, action vs browser_action / page_action, host_permissions split, web_accessible_resources object-form" plus runtime restrictions ("no DOM, no XMLHttpRequest, no localStorage") — rather than vague language; closest to the 'lists multiple specific concrete actions' anchor.

3 / 3

Completeness

Explicitly answers both what ("Pure-reference catalog of the Manifest V3 test surface... Maps each manifest field that changed from MV2") and when ("Use as the manifest-surface reference when authoring extension tests across both browsers"), satisfying the explicit 'Use...when' trigger guidance that prevents a cap at 2.

3 / 3

Trigger Term Quality

Natural terms a user would say are present ("Manifest V3," "browser extensions," "Firefox," "extension tests across both browsers") but are buried under dense technical parentheticals and it uses "Chromium" rather than the more common "Chrome," missing common variations; not score 3 because jargon dominates the natural phrasings.

2 / 3

Distinctiveness Conflict Risk

Occupies a clear narrow niche (manifest-surface reference for Firefox + Chromium extension tests, manifest-field-keyed) with distinct triggers, making it unlikely to fire for the wrong skill; matches the 'clear niche with distinct triggers' anchor rather than the 'somewhat specific but could overlap' level below.

3 / 3

Total

11

/

12

Passed

Validation

93%

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

Validation15 / 16 Passed

Validation for skill structure

CriteriaDescriptionResult

metadata_version

'metadata.version' is missing

Warning

Total

15

/

16

Passed

Reviewed

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