v1.100.0

This release adds new diagnostic and configuration capabilities, hardens the board communication protocol, and improves error messaging for missing models and credentials.

What's New

• Adds docker agent doctor command for diagnosing model provider credentials and agent readiness
• Adds actionable errors when models or credentials are missing, with guidance on next steps
• Adds hooks.d drop-in directory (<config-dir>/hooks.d/*.yaml) and DOCKER_AGENT_CONFIG_DIR environment variable override for config directory
• Adds heartbeat idle watchdog to abort hung event streams in docker agent board
• Adds session aggregate cost reporting to GET /snapshot
• Adds machine-readable error codes to 404 responses for unknown session snapshots
• Adds heartbeat keepalives to idle /events SSE streams

Bug Fixes

• Fixes turn-boundary events being silently dropped when a subscriber's buffer overflows

Technical Changes

• Extracts lean TUI engine into a separate package and reorganizes UI components (status models, inline images, tool views, transcript, screen model) into a dedicated UI layer
• Adds documentation for docker agent board CLI reference and actionable model/credential errors in troubleshooting guide
• Adds tmux usage guidance for running docker agent board in a sandbox environment

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What's Changed

• docs: update CHANGELOG.md for v1.99.0 by @docker-read-write[bot] in #3487
• feat(cli): actionable errors for missing models and credentials (phase 1 of #3442) by @Sayt-0 in #3452
• feat(cli): add docker agent doctor for model and credential diagnosis by @Sayt-0 in #3489
• Lean tui UI split by @rumpl in #3492
• feat: harden control-plane protocol for reliable board communication by @dgageot in #3491
• docs: update CLI reference and troubleshooting for board and actionable errors by @aheritier in #3494
• Add tmux or running docker agent board in sbx by @dgageot in #3495
• feat: hooks.d drop-in directory and config-dir env override by @Sayt-0 in #3496

Full Changelog: v1.99.0...v1.100.0