September 22, 2026 · Muhammad Umar · More by Muhammad Umar
Liquid's New block and partial Tags, Explained
Shopify's July '26 developer preview adds block and partial Liquid tags for composing theme pages, plus new Theme Check 3.28.0 lint rules.
In July 2026, Shopify's Liquid developer preview added two tags aimed at a specific pain point in theme development: page structure spread across sections, JSON templates, and section groups instead of living in one place. The block tag renders a reusable theme block directly from a template — you name the block, pass its inputs, and provide body content, much the way the render tag works today. The partial tag defines a named region of server-rendered HTML that JavaScript can refresh without reloading the full page — partial hydration without pulling rendering into a client-side framework.
Together, the two tags let a developer compose a page's structure in Liquid and add dynamic storefront interactions in the same file, which is also the stated reasoning behind the feature: developers and coding agents can read and edit page structure in one place instead of tracing it across separate section, template, and section-group files.
What Ships Alongside: Theme Check 3.28.0
Shopify paired the preview with Theme Check 3.28.0, and the new rule set is a good signal of the discipline expected from Liquid-first themes. On the complexity and file-hygiene side: LiquidComplexity flags files above a cyclomatic-complexity threshold of 120, LiquidNestingDepth flags control-flow nesting past a default depth of 10, MaxFileSize flags oversized theme files, and ExcessiveSettingsCount flags section or block schemas declaring more than 40 top-level settings by default.
A second cluster checks that block arguments actually match their schema and doc declarations: BlockArgumentSettingCollision, DuplicateBlockArguments, MissingBlockArguments, UnknownBlockSetting, UnrecognizedBlockArguments, and ValidBlockArgumentTypes. A third checks tag placement and uniqueness within a file: SchemaOncePerFile, SchemaSectionOrBlockOnly, StylesheetOncePerFile, StylesheetTagInWrongFile, JavascriptOncePerFile, and JavascriptTagInWrongFile. The same 3.28.0 release also replaced Theme Check's parser-combinator-based Liquid/HTML parser with a hand-written recursive-descent one, described as significantly faster and able to recover from malformed input instead of bailing out.
Additive, Not a Replacement
None of this touches existing themes. Sections, theme settings, and JSON templates continue to work exactly as they do now — the preview adds a Liquid-first composition model alongside that architecture, not instead of it. To try it, a development store needs the Liquid July '26 developer preview enabled, and Shopify suggests starting from the skeleton theme release candidate or adding the new tags into an existing theme incrementally.
For teams scoping a rebuild, that framing matters: this is a preview with new tags and new lint infrastructure behind it, not a migration deadline. It's worth prototyping a section or two against the block and partial tags to see how the new Theme Check rules behave on real code, while the bulk of a production theme keeps shipping on the current model.