Otp Manager

OTP Manager Skill

Reusable skill for managing Erlang/OTP 28.3.1 in Claude Code Web environments.

Purpose

Provides automated procedures for:

• OTP Installation: Download and build OTP 28.3.1 from Erlang Solutions
• OTP Verification: Check installed version and compilation readiness
• OTP Cleanup: Remove build artifacts and cached files

Commands

/otp-manager fetch-build

Download and build OTP 28.3.1 from official Erlang Solutions packages.

Behavior:

1. Check if OTP 28.3.1 is already installed (idempotent)
2. Download erlang-solutions repository package
3. Install OTP 28.3.1 via apt-get
4. Verify installation success
5. Return status + version

Idempotency: Safe to run multiple times. Skips installation if OTP >= 28.3.1 already exists.

Error Handling:

• Network timeout: Retries 3 times with exponential backoff
• Package installation failure: Clears cache and retries
• Permission denied: Reports error (requires sudo)
• Version mismatch: Reports installed version vs required

Output:

✅ OTP 28.3.1 installed successfully
   Version: 28.3.1
   Location: /usr/lib/erlang
   Time: 45s

Example:

/otp-manager fetch-build
# Downloads and installs OTP 28.3.1
# Returns: exit code 0 (success) | 1 (failure)

/otp-manager verify

Check OTP version and verify compilation readiness.

IMPORTANT: Always source the environment file first to ensure OTP 28 is used:

source .erlmcp/env.sh

Behavior:

1. Source .erlmcp/env.sh (ensures OTP 28.3.1 in PATH)
2. Detect installed OTP version (erl -noshell -eval)
3. Compare against required version (28.3.1)
4. Test basic compilation (rebar3 version)
5. Return verification result

Checks Performed:

• OTP version >= 28.3.1
• erl command available (from .erlmcp/env.sh)
• rebar3 command available
• Basic compilation works

Output:

✅ OTP verification passed
   Installed: 28.3.1
   Required:  28.3.1
   rebar3:    3.24.0
   Status:    READY

Exit Codes:

• 0: Verification passed (OTP >= 28.3.1)
• 1: OTP not found or version too low
• 2: OTP found but rebar3 missing
• 3: OTP found but compilation test failed

Example:

/otp-manager verify
# Sources .erlmcp/env.sh, checks OTP version and compilation readiness
# Returns: exit code 0-3 (see above)

/otp-manager clean

Remove OTP build artifacts and cached files.

Behavior:

1. Remove build artifacts in /tmp/erlmcp-build/
2. Clear apt-get cache for erlang packages
3. Remove lock files in .erlmcp/cache/
4. Preserve installed OTP binaries (safe cleanup)

Safety:

• Does NOT uninstall OTP (only removes build artifacts)
• Does NOT remove user code or dependencies
• Does NOT affect rebar3 project builds

Output:

✅ OTP cleanup complete
   Removed: 123 MB build artifacts
   Cleared: 45 MB apt cache
   Preserved: OTP 28.3.1 installation

Example:

/otp-manager clean
# Removes build artifacts and cache
# Returns: exit code 0 (success)

Integration with Subagents

This skill can be preloaded into subagents for autonomous OTP management:

Verifier Subagent (.claude/agents/verifier.md):

preload_skills:
  - otp-manager

Build Engineer Subagent (.claude/agents/build-engineer.md):

preload_skills:
  - otp-manager

Once preloaded, subagents can invoke OTP manager commands autonomously:

# Verifier checks OTP before running tests
/otp-manager verify
if [ $? -eq 0 ]; then
  rebar3 eunit
fi

# Build engineer fetches OTP if missing
/otp-manager verify || /otp-manager fetch-build

Error Recovery

The skill implements robust error recovery:

Example: Network Timeout Recovery

⚠️  Network timeout downloading erlang-solutions package
🔄 Retry 1/3 (delay: 1s)...
⚠️  Network timeout downloading erlang-solutions package
🔄 Retry 2/3 (delay: 2s)...
✅ Download successful

Implementation Details

Source Files

1. otp_fetch_build.sh (120 lines):

   • Downloads OTP 28.3.1 from erlang-solutions.com
   • Installs via apt-get with retry logic
   • Verifies installation success
   • Creates lock file for idempotency

2. otp_verify.sh (50 lines):

   • Detects OTP version via erl command
   • Compares against required version
   • Tests rebar3 availability
   • Returns structured exit codes

3. otp_clean.sh (30 lines):

   • Removes build artifacts
   • Clears apt cache
   • Preserves installed OTP

Design Principles

• Idempotent: All commands safe to run multiple times
• Fail-Safe: Clear error messages, no silent failures
• Cloud-Native: Works in ephemeral VM environments
• Reusable: Can be invoked by multiple subagents
• Auditable: Logs all operations to .erlmcp/otp-manager.log

Testing

Test suite location: test/otp_manager_skill_tests.erl

Test Coverage:

• ✅ Idempotency: fetch-build twice produces same result
• ✅ Version detection: verify detects OTP 28.3.1 correctly
• ✅ Error handling: Network timeout triggers retry
• ✅ Clean operation: Removes artifacts without breaking OTP
• ✅ Slash command: /otp-manager invocation works
• ✅ Subagent integration: Can be preloaded into verifier

Running Tests:

rebar3 eunit --module=otp_manager_skill_tests

Expected output:

Testing otp_manager_skill_tests
  All 6 tests passed.

Related Files

• .claude/hooks/SessionStart.sh - Uses fetch-build logic on session start
• .claude/agents/verifier.md - Preloads this skill for OTP verification
• .claude/agents/build-engineer.md - Preloads this skill for OTP management
• .claude/settings.json - References otp-manager in skill registry

Changelog

v1.0.0 (2026-02-01)

• Initial implementation
• Commands: fetch-build, verify, clean
• Integration with verifier and build-engineer subagents
• Test coverage: 6 test cases
• Spec: AUTONOMOUS_IMPLEMENTATION_WORK_ORDER.md:WO-006

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