feat: ARM tarball builds + arch-aware download

[AhmedTMM]

Summary

• Add ARM64 build matrix entries for native binary agents (zeroclaw, opencode, hermes, claude) in the agent-tarballs workflow
• Update agent-tarball.ts to detect remote VM arch via uname -m and download the correct tarball
• Change release strategy from delete-recreate to create-if-not-exists + per-arch upload (supports multiple arch assets per tag)
• Document ARM build requirements in discovery.md for future agents

Test plan

• Verify workflow runs on both ubuntu-latest (x86_64) and ubuntu-24.04-arm (arm64)
• Verify both arch tarballs upload to the same release tag
• Verify agent-tarball.ts selects correct URL based on remote VM uname -m
• bunx @biomejs/biome check src/ passes
• bun test passes (1415 tests)

🤖 Generated with Claude Code

[louisgv]

Security Review

Verdict: APPROVED
Commit: adc2658

Findings

[LOW] .github/workflows/agent-tarballs.yml:166-169 — Unquoted pipe to grep/while loop

• The grep pattern spawn-agent-${AGENT_NAME}-${ARCH}- is not anchored and could match unexpected filenames
• The while read loop processes untrusted release asset names from GitHub API
• Mitigation: Asset names are already filtered by gh release view --json assets --jq ".assets[].name", limiting exposure. The delete-asset command uses the exact name string without shell expansion.
• Impact: Negligible — GitHub asset names are constrained by GitHub's API validation

[PASS] packages/cli/src/shared/agent-tarball.ts:74-77 — URL validation

• Strong regex validation prevents shell injection
• Both x86 and ARM URLs validated independently
• Blocks dangerous shell metacharacters

[PASS] packages/cli/src/shared/agent-tarball.ts:85-95 — Conditional sudo and arch detection

• Safe variable expansion and arch detection
• URLs properly single-quoted in conditional branches
• Double-quoted expansion only for validated variables

[PASS] .github/workflows/agent-tarballs.yml:42 — Dynamic runner selection

• Safe GitHub Actions matrix conditional

Tests

• bash -n: N/A (workflow YAML, TypeScript)
• bun test: PASS (679 pass, pre-existing failures unrelated)
• Lint: PASS (0 errors)
• curl|bash safety: OK — URL validation prevents injection
• macOS compat: N/A (TypeScript only)

Architecture Review

The PR safely implements ARM support for agent tarballs:

1. Build matrix extension — Adds arm64 builds for native-binary agents while keeping npm-based agents x86_64-only
2. Arch-aware download — Remote VM detects uname -m and selects appropriate tarball URL
3. Rolling release strategy — Multiple arch builds upload to same release tag with per-arch cleanup
4. Backward compatibility — Falls back to x86_64 if only one arch available

No critical or high-severity issues found. Code follows project security standards.

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-- security/pr-reviewer