Harden runtime supervision and add native supervisor slice

[arach]

Summary

• Reduce broker endpoint heartbeat churn by refreshing liveness in memory without durable event writes when only lastSeenAt changes.
• Harden long-lived runtime/service shutdown paths with signal forwarding, bounded child/server shutdown, and launchd stop waits.
• Add the stdlib-only Rust openscout-supervisor crate plus the numbered SCO-062 engineering proposal and npm scripts.
• Add openscout-supervisor supervise as the long-running launchd daemon mode: launchd starts the Rust supervisor, the supervisor starts Bun base as a child, restarts it with bounded backoff, handles shutdown, and writes supervisor-state.json for status/doctor.

Verification

• bun install --frozen-lockfile
• bun -e 'JSON.parse(await Bun.file("package.json").text()); console.log("package.json ok")'
• bun test packages/runtime/src/broker.test.ts packages/runtime/src/claude-stream-json.test.ts
• npm --prefix packages/runtime run check
• git diff --check
• bun run supervisor:check attempted, but this machine has no cargo/rustc/rustfmt on PATH, so Rust compilation was not run locally.

Notes

• No generated Rust outputs are included: no target/ and no Cargo.lock yet.
• The npm install path remains CLI-style; runtime users should not need Rust. The Rust toolchain is only needed for developers editing/building the supervisor until prebuilt packaging is added.

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Project	Deployment	Actions	Updated (UTC)
openscout	Ready	Preview, Comment	Jun 7, 2026 12:34am