SHOWBOAT_REMOTE_URL feature

[simonw]

Fetch https://gist.githubusercontent.com/simonw/7d4a02f8b6672ecd6be4fbadc0d0237f/raw/e6f5e4b0d1c0883a80df707411e4df51052c3910/plan.md and use that as your plan and build it using red/green TDD

Refs:

• Showboat remote feature #17

Earlier planning transcript: https://claude.ai/code/session_01D71x3zZWgSA11WEe791PXV

Summary

This PR adds webhook integration to Showboat, allowing document events (initialization, notes, code execution, images, and deletions) to be posted to a remote server via the SHOWBOAT_REMOTE_URL environment variable.

Key Changes

• New remote module (cmd/remote.go): Implements webhook posting functionality with three main functions:

  • postSection(): POSTs document sections (init, note, exec commands) as form-encoded data
  • postImage(): POSTs image blocks as multipart/form-data
  • postPop(): POSTs document deletion events
  • documentID(): Extracts the document ID from title blocks

• Document ID tracking:

  • Added DocumentID field to TitleBlock struct to uniquely identify documents
  • Init() now generates a UUID for each new document
  • Document IDs are persisted in markdown as HTML comments (<!-- showboat-id: ... -->)
  • Parser and writer updated to handle document ID comments

• Event posting integration:

  • Note() posts note events to remote server
  • Exec() posts code execution events with language and output
  • Image() posts image events with multipart form data
  • Pop() posts document deletion events
  • All remote operations are non-blocking warnings; errors don't fail the command

• Comprehensive test coverage:

  • New cmd/remote_test.go with 11 tests covering all webhook scenarios
  • Tests verify correct payload formats, error handling, and no-op behavior when env var is unset
  • Integration tests in cmd/build_test.go verify event posting from high-level commands
  • Parser and writer tests verify document ID round-tripping

Implementation Details

• Remote posts use a 10-second timeout to prevent blocking
• All HTTP errors are logged to stderr as warnings but don't interrupt the command
• Document IDs are optional; operations work normally if SHOWBOAT_REMOTE_URL is unset
• Image posting uses multipart/form-data; other operations use form-urlencoded
• UUID dependency (github.com/google/uuid) is now a direct dependency (was indirect)

https://claude.ai/code/session_01Qs1QQwD6Zj3mMRDW8N5c4H

[simonw]

Manually tested as part of this and it works great:

• Implement datasette-showboat plugin with document streaming datasette-showboat#1