CHANGELOG.md

Changelog

All notable changes to the Go module are documented here. Go releases use the same version number as the Python, TypeScript, and Java packages.

[Unreleased]

[2.5.0] — 2026-09-28

Changed

• Validation now rejects email, URL, number, date picker, time picker, and rich text input placeholders over 150 characters, and dispatch-action configurations whose trigger_actions_on list is empty or has more than two triggers. Plain-text input placeholders were already limited to 150 characters.
• A dispatch-action configuration without trigger_actions_on is now rejected with MissingRequired, matching Slack's blocks.validate.
• Video block alt_text now accepts up to 2000 characters, including an empty string, matching Slack's validator (previously 1 to 200 characters).
• Validate now rejects column_settings on a data_table block with InvalidUsage; Slack supports column_settings only on the plain table block.
• Validation now follows Slack's blocks.validate more closely. Newly rejected:
  • Rich text list indent outside 0-8, negative offset, and list, quote, and preformatted border outside 0-1; image block title over 2000 characters; video thumbnail_url or video_url over 3000 and title_url or provider_icon_url over 2000 characters; view external_id over 255 characters; plain-text input min_length outside 0-3000 or max_length below 1; rich text input min_lines or max_lines outside 1-100; multi-select max_selected_items below 1; negative data table row_header_column_index; more than 20 table column_settings; containers with no child blocks; and plans with more than 50 tasks or duplicate task_ids.
  • Conversation filters with an empty include list or a type other than im, mpim, private, or public, including filters on raw conversation selects passed to Validate.
  • Slack file IDs that do not match ^F[A-Z0-9]{8,}$, in NewSlackFile and in image slack_file objects passed to Validate.
  • Messages, message responses, and webhook messages whose markdown blocks total more than 12,000 characters or whose data table cells total more than 20,000 characters.
  • A standalone task card with pending status (TypeMismatch). Plan tasks can still be pending.
  • Missing required fields (MissingRequired), checked at Build: a Slack icon's Name, a plan's Tasks, a task card's Status (also for plan tasks), a number input's IsDecimalAllowed, an attachment's Blocks, and a workflow button's ActionID. Icon buttons and file blocks still default icon and source.
• Newly accepted: input blocks in messages, data_visualization blocks in App Home, and tables with fewer or more column_settings than columns (up to 20).
• ActionID is now optional on every interactive element except rich text inputs and workflow buttons; when it is not set, no action_id is sent. The 255-character limit still applies when it is set.
• Also newly accepted: task card source URLs of any length (including empty), empty markdown block text, modals and App Home tabs with no blocks, and table rows with different numbers of cells (data_table rows must still match).
• ImageBlockBuilder gains SlackFile; an image block needs exactly one of ImageURL or SlackFile.
• RichTextInputBuilder.InitialValue now takes a *RichTextBlockBuilder instead of a *RichTextBuilder, since Slack requires a rich_text block.

[2.4.0] — 2026-09-17

This coordinated release introduces the C# package, published to NuGet as Slackblocks, and moves all five packages onto one shared release number. The Go public API and wire format are unchanged.

Changed

• Coordinated release validation now requires the Python, TypeScript, Java, and C# package manifests and all five language changelogs to agree before any tags are created.
• Project documentation now includes the C# implementation alongside the existing Python, TypeScript, Go, and Java variants.

[2.3.0] — 2026-09-16

This coordinated release introduces the Java package and replaces the any parameters on Go builder methods with typed parameters. The wire format is unchanged.

Changed (breaking for Go callers)

• Builder methods take typed parameters instead of any. Nested fields accept role interfaces (Block, Element, InputElement, ContextElement, ContextActionsElement, TableCell, DataTableCell, Chart, RichTextBlockElement, RichTextSectionElement, and TextObject) or a concrete builder such as *ConfirmationBuilder. Only slackblocks builders implement the interfaces, so a value of the wrong kind no longer compiles.
• Text fields take a string. Pass a text object with the new companion method, such as TitleObject or FieldObjects.
• Enumerated fields take named string types with constants, such as ButtonStyle and ButtonStylePrimary. Untyped string constants still compile.
• Rich text styles take RichTextStyle, table rows take typed slices such as []TableCell, numeric chart and cell values take float64, and message metadata takes Object.
• NewAccordion().Sections takes *AccordionSectionBuilder values and NewPaginator().Blocks takes Block values.
• Raw Object values and maps are no longer accepted by typed fields; use Set(field, value) for wire-format values.
• Builder documentation now states each field's Slack limit, whether it is required, and links to Slack's reference, and a test runs every Go snippet in the Using Blocks guide.

Changed

• Coordinated release validation now requires the Python, TypeScript, and Java package manifests and all four language changelogs to agree before any tags are created.
• Project documentation now includes the Java implementation alongside the existing Python, TypeScript, and Go variants.

[2.2.0] — 2026-09-02

The first public Go release of slackblocks, versioned in step with the Python and TypeScript packages. The module supports Go 1.22 and newer.

Added

• Fluent concrete builders for Slack Block Kit composition objects, elements, blocks, messages, attachments, responses, modals, and App Home payloads.
• Typed validation errors and complete payload validation for required fields, length and collection limits, supported block surfaces, and modal submission rules.
• Direct slack-go/slack interoperability: top-level block builders implement slack.Block and can be passed directly to slack.MsgOptionBlocks.
• Shared conformance coverage against the same valid and invalid JSON fixtures used by the Python and TypeScript implementations.
• Higher-level Accordion and Paginator components that expand into ordinary Slack blocks.
• Dedicated documentation, examples, generated-builder verification, and a CI matrix covering Go 1.22 and the latest stable Go release.