The Two Guardrails

Agento uses a two-tier guardrail system designed to prevent broken code and eliminate hallucination drift during autonomous coding sessions.

Overview of the Guardrail Halves

Proposed Edit (write_file / edit_file)
      │
      ▼
┌────────────────────────────────────────────────────────┐
│  LINTOs (PRE-WRITE, blocking)                          │
│  - Evaluates rules against proposed in-memory buffer   │
│  - Hard gate -> Rejects edit immediately               │
│  - Justify gate -> Requires explicit human consent     │
└──────────────────────────┬─────────────────────────────┘
                           │ Passed
                           ▼
                    File Written to Disk
                           │
                           ▼
┌────────────────────────────────────────────────────────┐
│  CHECKS (POST-WRITE, non-blocking feedback)            │
│  - Runs fast diagnostics (compiler, typecheck, lint)   │
│  - Extracts newly introduced errors                    │
│  - Surfaces actionable feedback to agent prompt        │
└────────────────────────────────────────────────────────┘

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1. Pre-Write Guardrails: LINTOs

LINTOs are deterministic rules that evaluate proposed code changes before they are written to disk.

• Execution Timing: In-memory, immediately prior to file mutation.
• Behavior: Blocking. If a rule is violated, the file write is stopped.
• Purpose: Enforcing non-negotiable repository standards (e.g. banning any casts, preventing hardcoded credentials, protecting configuration files, and ensuring architectural boundaries).
• Gate Levels:
  • hard: The mutation is rejected immediately, returning rule feedback to the model to rewrite the code.
  • justify: Pauses execution to require human approval or a justified override.

---

2. Post-Write Verification: Checks

Checks are non-blocking diagnostic commands (such as tsc, cargo check, eslint, or unit tests) that run after an edit is successfully written to disk.

• Execution Timing: Immediately after a file write or on milestone completion.
• Behavior: Non-blocking feedback. Checks never prevent a file from being written; instead, they capture compiler and linter output to provide the agent with instant, real-world feedback.
• Noise Filtering: Agento filters out pre-existing repository errors and reports only the new errors introduced by the agent’s recent edits.
• Tiers:
  • Tier 1 (Fast Micro-Checks): Rapid checks running within strict time budgets (<2s) on every edit.
  • Tier 2 (Milestone Verification): Authoritative test suite and full build checks run upon completing a milestone.