# Constraints – zlh-grind

This repository is strictly for *decision tracking*, *constraints*, and *ground rules*.  
It is not an implementation repo.

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## Execution model constraints
- zlh-agent executes installer logic as **embedded scripts**.
- Embedded scripts must not rely on filesystem-relative paths (`$0`, `dirname`, etc.).
- Any shared logic must be executed in the **same shell session** as its callers.

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## Installer contract constraints
- Installers must be:
  - deterministic
  - artifact-driven
  - idempotent
  - strict (`set -euo pipefail`)
- All runtime installers require explicit environment projection:
  - `RUNTIME_VERSION` is mandatory
  - artifact naming may be customized via `ARCHIVE_PREFIX`
- Installers must not parse JSON or agent state files.

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## Responsibility boundaries
- API declares *intent* (runtime, version, container type).
- Agent translates intent into:
  - environment variables
  - filesystem operations
  - installer execution order
- Installers perform no orchestration or decision-making.

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## Anti-patterns (explicitly forbidden)
- Mega-installers that handle multiple runtimes via branching logic
- Package-manager–based installs (apt, nvm, pyenv, sdkman)
- Weakening installer strictness to accommodate agent bugs

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