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AgentCompany/builtin-skills/software-engineer/clean-code/references/obj-data-abstraction.md
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ZacharyZhang-NY e74dafcd36 Silence render-disposed spam, unbreak bundled skills, drop board wake
Three independently ugly bugs that all fed the same log flood:

* Electron's `WebFrameMain.send` writes every "Render frame was disposed"
  to stderr via `console.error`. When the worker fans a second
  agent-event past a reloading renderer, we produced thousands of
  identical lines and stalled the main loop on stderr I/O. Added a
  `mainFrame.detached` guard so the send is short-circuited before
  Electron's own catch block fires, and installed a targeted filter in
  `suppress-warnings.ts` (now actually imported from the entry point)
  so the specific `console.error("Error sending from webFrameMain:"…)`
  noise never reaches the terminal. Any other payload still surfaces.

* `dispatchAgentMessage` accepted the human-reader sentinel as a wake
  target when an agent replied to `__board__` — `wakeAgentIfPossible`
  then called `db.getAgent("__board__")`, threw, and the dispatcher
  kept repeating on every send. Strip `HUMAN_SENDER_ID` at
  `resolveMessageWakeTargets`, and keep a defense-in-depth guard in the
  heartbeat so a stray caller (future automation fan-out) cannot
  reintroduce the crash.

* Pi's skills loader rejects any SKILL.md whose frontmatter `name`
  diverges from its parent directory. The four bundled `my-writing-style`
  copies declared `name: writing-style-skill`, so every install emitted
  a warning and dropped the skill. They also lived as orphan gitlinks
  (mode 160000 without .gitmodules), and the global `*.md` gitignore
  hid every other SKILL.md from version control. Fixed the frontmatter
  to match the dir, converted the dangling submodules to plain trees,
  and allowlisted `builtin-skills/**/*.md` so a fresh clone carries the
  catalogue instead of silently losing it.
2026-04-20 08:13:48 -04:00

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---
title: Hide Data Behind Abstractions
impact: MEDIUM-HIGH
impactDescription: enables implementation changes without ripple effects
tags: obj, abstraction, encapsulation, data-hiding
---
## Hide Data Behind Abstractions
Objects hide their data behind abstractions and expose functions that operate on that data. Data structures expose their data and have no meaningful functions. Do not mix these concepts.
**Incorrect (exposing implementation):**
```java
// Exposes internal representation - clients depend on Cartesian coordinates
public class Point {
public double x;
public double y;
}
// Using it forces clients to know the implementation
double distance = Math.sqrt(point.x * point.x + point.y * point.y);
```
**Correct (hiding behind abstraction — immutable):**
```java
// Hides representation - could be Cartesian, polar, or something else
public interface Point {
double getX();
double getY();
double getR();
double getTheta();
static Point fromCartesian(double x, double y) {
return new CartesianPoint(x, y);
}
static Point fromPolar(double r, double theta) {
return new PolarPoint(r, theta);
}
}
// Clients work with the abstraction
double distance = point.getR(); // Works regardless of internal representation
Point moved = Point.fromCartesian(point.getX() + dx, point.getY() + dy);
```
**Key insight:** The abstraction is not just about using getters/setters. It is about hiding the form of the data and exposing operations that work with the abstract concept. Prefer immutable objects with factory methods over mutable objects with setters — immutable designs are easier to reason about, thread-safe by default, and less prone to bugs.
Reference: [Clean Code, Chapter 6: Objects and Data Structures](https://www.oreilly.com/library/view/clean-code-a/9780136083238/)