Harden AI agent rules and compile learning workflow

docs/00-governance/patterns_and_antipatterns.md

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+# Patterns and Anti-Patterns
+**Last Updated:** 2026-04-05
+
+Capture recurring implementation patterns that impact compile stability.
+
+## Pattern Entry Template
+- **Context:** where this applies
+- **Good pattern:** concise example/description
+- **Anti-pattern:** concise example/description
+- **Why it matters:** one sentence
+
+## Starter Patterns
+1. **NT8 override signatures**
+   - Good pattern: copy exact signature from official NT8 docs before coding.
+   - Anti-pattern: infer or copy from outdated examples.
+   - Why it matters: prevents `CS0115` and runtime integration drift.
+
+2. **Access modifier on overrides**
+   - Good pattern: use `protected override` for NT8 lifecycle/event methods.
+   - Anti-pattern: `public override` or `private override`.
+   - Why it matters: prevents `CS0507`.
+
+3. **C# 5 compatibility discipline**
+   - Good pattern: `string.Format`, explicit null checks, block-bodied members.
+   - Anti-pattern: string interpolation, null-conditional, expression-bodied members.
+   - Why it matters: prevents avoidable language-version compile failures.
+
+4. **Managed order sequencing**
+   - Good pattern: set stop/target before entry on the same bar.
+   - Anti-pattern: entry first, then stop/target.
+   - Why it matters: avoids silent behavior defects and rejected assumptions.
+
+5. **Scope-first fixes**
+   - Good pattern: smallest safe change in scoped files only.
+   - Anti-pattern: broad cleanup or adjacent-file edits during bugfix.
+   - Why it matters: reduces regression risk and review churn.