[danew]

Summary

Prepare the stable v0.5.0 CLI release from the exact implementation shipped in v0.5.0-preview.9 (507a2ec).

• Bump the native package version in Cargo.toml and Cargo.lock to 0.5.0.
• Add CHANGELOG.md with release notes and upgrade guidance for default text output, targeted agent setup, device authorization, Commands API browser actions, download retrieval, and changed session semantics.
• No application code or dependency changes. The npm bootstrap package has its own version and is not part of this native release preparation.

Verification

• cargo fmt --all --check
• cargo metadata --locked --format-version 1 --no-deps
• cargo test --locked --test cli_blackbox version_exits_zero_and_prints_version
• Built binary reports exactly steel 0.5.0.
• Parsed lockfile comparison confirms the dependency graph is unchanged.
• git diff --check

Release steps after merge

• Tag the reviewed merge commit as v0.5.0 and push the tag to run the existing release workflow.
• Verify all four platform archives, checksums, and attestations, and confirm GitHub stable/latest points to v0.5.0.
• Verify setup.steel.dev installs the stable release.
• Merge the stable onboarding guide in https://github.com/steel-dev/setup/pull/1.
• Smoke-test the public stable install, device approval/resume, skill loading, browser/download task, and exact-session cleanup.
• Update evaluation pins to stable while preserving preview results.

This PR does not create or push a release tag, publish a release, or change stable/latest.

[danew]

Stable release published and verified

• Tagged the merge commit 53acc2b as v0.5.0.
• Release workflow succeeded: https://github.com/steel-dev/cli/actions/runs/42699765231
• Stable release/latest verified: https://github.com/steel-dev/cli/releases/tag/v0.5.0
• All four platform archives match both published checksum records. GitHub attestations verified against this source commit, refs/tags/v0.5.0, and the release workflow on hosted runners.
• An isolated macOS ARM64 installation through the documented setup.steel.dev curl/install-only path reports exactly steel 0.5.0 and matches the verified release binary.
• Linux ARM64 native and Linux AMD64 emulated version/help smoke tests passed with networking disabled.
• Intel macOS archive/provenance verified; runtime not exercised.
• Published release notes include the changelog and stable download links.

Verification distinction: an initial default Python urllib request to setup.steel.dev/install.sh returned HTTP 403; the documented curl delivery path and resulting installation passed. No fresh device authorization or full stable agent task was run during this package verification.