Mosoo v0.5.0 (Alpha): Pi runtime

Mosoo v0.5.0 adds Pi as a selectable runtime for durable Project Sessions. Run Pi with your own OpenAI-compatible model, use tools and workspace files, and continue work through the same Session.

Pi runtime

• Choose Pi in the console or API. Select Pi with a configured custom model in the Agent editor, or use harness: "pi" and provider: "openai-compatible" in an inline execution configuration. Custom providers continue to default to OpenCode until Pi is explicitly selected. #658
• Native Pi execution and continuation. The Driver uses Pi's native RPC transport with streamed text, thinking and tool events, cancellation, usage reporting, workspace files, Skills, and the existing remote MCP proxy. Native Session state is included in the checkpointed workspace; missing or mismatched continuation state fails explicitly instead of silently starting a new conversation.
• Correct tool results, including silent commands. The integration preserves tool-to-message associations and completed tool arguments, and handles commands with no output without failing protocol validation. Driver #131
• Project credentials stay in the control plane. Pi receives a model-scoped proxy grant rather than the raw provider key.

To get started, add a custom provider with an HTTPS endpoint and an explicitly declared model supporting Chat Completions streaming and tool calls, then select Pi. This release accepts text input; files are available through the Session workspace. Execution uses full access within that sandbox; per-tool restrictions and interactive approval policies are not supported.

See the Pi runtime guide and the companion Mosoo CLI v0.5.0, including Pi examples and updated Skill references. Mosoo Health also includes Pi and reports Unknown when no production sample has been observed.

Upgrade and compatibility

• The matched Driver revision is 0dfccf2bf4881db43fa3706488fd243d20d468dd, with Pi 0.99.2. Driver protocol remains 6.
• The API adds SandboxPi and the additive v4-pi-runtime Durable Object migration. No new D1 SQL migration is added since v0.4.0. Deploy the matched API and image set, and preserve existing sandbox namespaces and bindings. Follow the production runbook.
• Production currently keeps MOSOO_RUNTIME_IMAGES_ENABLED=false: Pi executes through the union image, while the dedicated Pi image is deployed and ready. Enabling split-image allocation is a separate rollout. Rollback must retain compatible Session state, bindings, and a matched Driver.
• Production migration checks now omit unnecessary ledger DDL when all configured migrations are already applied, retain schema checks, and include stdout in failure diagnostics. Pending migrations still follow the normal apply path; unreadable or inconsistent ledgers stop deployment. #659, #660

Other fixes

• Restrict development login to loopback origins. #656
• Require HTTPS OAuth endpoints without embedded URL credentials or fragments for MCP credential transport. #657

Release scope and verification

This source release is pinned to 176672bdbb3a0cfc43ed1535633d00035197f880, the reviewed source already deployed to production on October 8, 2026. Publishing the tag and release notes does not redeploy Workers or apply migrations.

• The release tree exactly matches the successful Linux repository check. The macOS full gate retained known platform-specific process-test failures; it is not reported as passing. No source changes were made for this release, so those suites were not rerun for tag publication.
• Staging acceptance used Pi with a real DeepSeek custom endpoint through the CLI: tool execution, silent commands, file write/read, and follow-up after Driver restart passed. Native Session references and file contents were preserved. These checks do not establish arbitrary long-idle recovery guarantees.
• Production acceptance confirmed the new API and Web at 100% traffic, all five runtime images ready, matching deployed image digests and Driver bundle bytes, healthy HTTP/GraphQL responses, and compatibility redirects. This was infrastructure acceptance; no new paid production model call was made.
• Health and multilingual documentation are deployed. Companion CLI v0.5.0 assets and Skill were verified; the Homebrew update and its subsequent contract CI passed. Their API contract provenance remains the Pi integration commit 63b6365; the later Host commits change deployment tooling only.

Pi builds on contributions in Driver #129 and Host #654, with the final integration in Host #658 and Driver #131.

Alpha status

Mosoo remains in active Alpha development. Product boundaries, APIs, data models, and deployment methods may change without backward-compatibility guarantees.

Full changelog: v0.4.0...v0.5.0