STF 2025–2026 Milestone 3 completion report

[dahlia]

Now that the work for Milestone 3, “ActivityPub Debug and Development Tools (Part 2),” is complete, we need to prepare and submit a progress report to the Sovereign Tech Agency as stipulated in our service agreement. This report is a prerequisite for invoicing the third milestone payment.

The task is to create a document that summarizes the work done and provides evidence of completion. According to the reporting guidelines, this can be achieved by collating links to all relevant commits, pull requests, and other source code management actions. Once the report is finalized, it will be sent to our program manager.

Milestone scope

Milestone 3 continued the ActivityPub debugging toolchain started in Milestone 2, delivering two major components shipped in Fedify 2.0.0 (released February 22, 2026):

1. @fedify/debugger — an embedded real-time ActivityPub debug dashboard that wraps any Federation object and provides a browser-based UI showing live traffic, signature verification, and delivery details
2. @fedify/lint — an ESLint and Deno Lint plugin with 21 rules that analyze federation setups and guide developers on missing or incorrect configurations
3. setOutboxPermanentFailureHandler() — a new API for handling permanent delivery failures with detailed error information
4. Full documentation for both tools at https://fedify.dev/

Deviations from contract language

Two implementation decisions differ from the original contract wording:

• Polling-based updates instead of WebSocket: The dashboard uses HTTP polling (3-second interval) rather than WebSockets, due to the lack of a cross-runtime WebSocket server API that works uniformly across Deno, Node.js, and Bun. The functional result (near-real-time visibility) is equivalent for the intended development use case.
• Lint plugin instead of CLI checklist tool: The checklist functionality was implemented as an ESLint/Deno Lint plugin rather than a standalone fedify checklist CLI command. This integrates more naturally into existing developer workflows (editor, CI/CD) and provides earlier, more actionable feedback.

Related issues and PRs

The following GitHub issues and pull requests contain the detailed work for this milestone:

Debug dashboard (@fedify/debugger)

• PR @fedify/debugger: Embedded ActivityPub debug dashboard #564: @fedify/debugger: Embedded ActivityPub debug dashboard
• Issue @fedify/debugger: Embedded ActivityPub debug dashboard #561: LogTape trace context injection
• PR Add handler for permanent delivery failures (410 Gone, 404 Not Found) #559: Permanent delivery failure handler (setOutboxPermanentFailureHandler)

Lint plugin (@fedify/lint)

• PR Linter to create federation with Fedify #494: @fedify/lint initial implementation
• PR Resolve issues related with fedify init #563: Integrate @fedify/lint into fedify init generated projects
• Issue ActivityPub implementation validator (CLI + lint plugin) #287: ActivityPub implementation validator (original feature request)
• Issue Create Issue and Pull Request Templates #297: Lint plugin feature request

Foundation (from Milestone 2)

• PR Add OpenTelemetry span events and missing instrumentation #483: OpenTelemetry span events
• PR Add FedifySpanExporter for distributed trace storage #502: FedifySpanExporter
• PR Add list() method to KvStore interface #500: KvStore.list()

Release

• Fedify 2.0.0 released on February 22, 2026
• Discussion Fedify 2.0.0: Modular architecture, debug dashboard, and relay support #580: Fedify 2.0.0 release announcement

All technical details, code changes, and completion evidence can be found in these linked resources.