Ygg v0.5.0

Ygg v0.5.0

Ygg v0.5.0 expands the executable-extension contract, adds supervised extension
lifecycle support and bounded task delegation, and hardens the default terminal
and graphical execution paths. It remains pre-1.0 software: configuration,
sessions, extension APIs, and provider behavior may evolve.

Ygg and its extensions are not operating-system sandboxes. They run with the
authority of the user who launches them; use OS isolation for untrusted
workspaces, models, or extension packages.

Install Ygg

Ygg requires rg (ripgrep). The version-pinned installer selects and verifies a
prebuilt binary for GNU/Linux x86-64, macOS x86-64, or macOS Apple silicon:

curl --proto '=https' --tlsv1.2 -LsSf \
  https://github.com/skaft-software/ygg/releases/download/v0.5.0/install-ygg.sh | sh

To compile the pinned release instead, install Rust 1.86 or newer:

curl --proto '=https' --tlsv1.2 -LsSf \
  https://github.com/skaft-software/ygg/releases/download/v0.5.0/install-ygg.sh \
  | sh -s -- --from-source

Or use Cargo directly:

cargo install --locked \
  --git https://github.com/skaft-software/ygg \
  --tag v0.5.0 \
  --bins \
  ygg-coding-agent

The installer and Cargo command install both ygg and ygg-host.

Upgrade from v0.4.0 or earlier

Re-run the pinned installer command above, using the same YGG_INSTALL_DIR if
an earlier installer used a custom location. Releases through v0.4.0 do not
have the ygg update command; the v0.5.0 installer replaces both binaries and
the packaged documentation while leaving ~/.ygg configuration, credentials,
sessions, and other user data untouched. Restart the shell, or run hash -r,
then confirm ygg --version reports 0.5.0.

For an existing Cargo installation, run the pinned cargo install command above
instead. After either upgrade path, an installed Serve package must be updated
separately:

ygg extension update ygg-serve

Install Ygg Serve

The graphical interface remains an optional application extension:

ygg extension install ygg-serve
ygg serve

The official package must exactly match Ygg 0.5.0. Supported artifacts are
provided for GNU/Linux x86-64, macOS x86-64, and macOS Apple silicon. Linux
musl targets are not supported.

Highlights

• Added executable-extension API 0.2 with feature negotiation, bounded
  concurrency, serialized writes, cancellation, progress, artifacts,
  lifecycle observations, secret brokerage, dynamic tool catalogs, and child
  agent sessions.
• Added automatic extension supervision with bounded restart backoff and stale
  generation fencing, plus Python SDK 0.2 support.
• Added provider-neutral durable session goals and metadata-gated Ultra
  reasoning with bounded V2 task delegation.
• Added isolated child sessions with private team storage and provenance
  records.
• Updated Codex discovery and Responses Lite handling to use advertised
  capabilities rather than model-name or subscription-plan inference.
• Made full host access the default and made --safe-mode the canonical
  approval-required mode. The hidden --safe alias remains accepted.
• Reworked controlled Bash classification with tree-sitter parsing and retained
  strict bounded execution semantics.
• Reworked compaction around bounded Pi-style recent-token retention and
  improved TUI liveness, completion rendering, and reasoning labels.
• Improved large-session discovery and long-session rendering performance.
• Added ygg update with install-method detection and version-pinned updates.

Compatibility and limitations

• The 0.2 extension contract is new; API 0.1 remains accepted as a
  backward-compatible text-oriented contract.
• Ultra and V2 delegation require matching capabilities in live provider
  metadata and are disabled conservatively when metadata is unavailable.
• The default full-access mode grants commands and workspace mutations the
  launching user's authority. Use --safe-mode or OS isolation for untrusted
  work.
• First-party MCP, browser, web-search, computer-use, memory, LSP, and
  subagent-orchestration packages are not included. The coding product does not
  yet configure an approval UI adapter or secret provider.
• Serve remains loopback-only and does not provide LAN pairing or native client
  applications.

Release acceptance

The deterministic configured-provider matrix is required by CI. Credentialed
OpenAI, Anthropic, OpenAI Chat, and native-audio checks are separately approved
and may be waived when release credentials are unavailable. See the
configured-provider acceptance record
for the exact policy and evidence.

See the changelog,
extension documentation, and
security policy
for the complete behavior and boundaries.