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:

•Check if OTP 28.3.1 is already installed (idempotent)
•Download erlang-solutions repository package
•Install OTP 28.3.1 via apt-get
•Verify installation success
•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:

code

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

Example:

bash

/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:

bash

source .erlmcp/env.sh

Behavior:

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

Checks Performed:

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

Output:

code

✅ 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:

bash

/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:

•Remove build artifacts in /tmp/erlmcp-build/
•Clear apt-get cache for erlang packages
•Remove lock files in .erlmcp/cache/
•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:

code

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

Example:

bash

/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):

yaml

preload_skills:
  - otp-manager

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

yaml

preload_skills:
  - otp-manager

Once preloaded, subagents can invoke OTP manager commands autonomously:

bash

# 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:

Error Class	Recovery Strategy
Network timeout	Retry 3x with exponential backoff (1s, 2s, 4s)
Package conflict	Clear apt cache and retry
Permission denied	Report to user (requires sudo)
Version mismatch	Report installed vs required version
Disk space	Report error (requires user intervention)

Example: Network Timeout Recovery

code

⚠️  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

•
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
•
otp_verify.sh (50 lines):
- •Detects OTP version via erl command
- •Compares against required version
- •Tests rebar3 availability
- •Returns structured exit codes
•
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:

bash

rebar3 eunit --module=otp_manager_skill_tests

Expected output:

code

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